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echnol !gv transferSea C>rant is a untque partnership of pub! tc and private sectors. c >mhlning tese irch. eiiuct>tii>n. »d ' ch"o> orn>c needs in oura""'onal netv ork of universtties meetin h n' ng ' ~

coastal, ocean, and Grea Lakes reg ions.

Published by the Calilornia Sea Grant College System. Ln>ieritt> " hfornia, 19'96.

i ~ s!ts ot' Califom>a.Additional single copies are available for Sl0 from: Calif>>rn>a Sea irant i>liege .'ii stem. L n' i'r ".950t! Gdman Dnve. La Jolla. CA 92093-023'>. �l9t 5~4-4444

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Tidal Wetland Restoration:

A SCientifiC PerSpeCtiVe andSouthern California Focus

Joy B. Zedler, Principal Author

Pacific Estuarine Research LaboratorySan Diego State University

San Diego, California

1996

California Sea Grant College SystemLniversity of California

La Jolla, California 92093-0232Publication No. T-038

il TIDAL WETLAND RESTORATION

ISBN No. 1-888691-02-6

Joy B. Zedler, Principal Author*

Contributors

John Boland, Ecologist, California Coas al CommissionKatharyn Boycr, Research Associate, PERL, San Diego S ate UniversityJohn Callav;ay, Research Assis ant Professor, PERL. San Diego Stale UniversityDana Johnsen, Research Associate. PERL. Sari Diego State L!niversi yThomas J. Kwak, Research Associate Prot'cssor, University of Arkansas

Barbara Kus, Adjunct Professor of Biology, San Diego State UniversityBruce Nyden, Manager, PERl, San Diego State UniversityLorraine Parsons, Research Ass<iciate, PERL, San Diego State Universi yStuart Phinn. Department of Geography, San Diego State UniversityDouglas A. Stow, Department of Geography, San Diego State University

Arf and DesignIllustrator, Donovan MclntireCover photo, Juliet e Murguia, Juliette Murguia PhotographyCover design. Leah Hewiu, Stephen Birch Aquarium-Museum Pubiications, Scripps institution of Oceanography

Cire arc Zedler, Joy B., Principal Author. l996. Tidal Wetland Res oration: A Scien iftc Perspective and SouthernCalifornia Focus. Published by the Califnrnia Sea Grant College Sys em, University of California, l.a Jolla, Cahfomia.Report No. T-03g.

CONTENTS

CONTENTS

Contributors .Preface VI

1 1 I3 6 6 77 7 78 8

10

1111121214151516

.18

40404141

Chapter 1: Pacific Coast Estuaries and Wetlands1.1 INTRODUCTION.

1.1.1 Comparisons with Other Coasts ............1.1.2 Tidal Patterns1.1.3 A Sample Pacific Coast Wetland.

1.2 NATURAL FUNCTIONS AND VALUES.1.2.1 Fisheries Support1.2.2 Pacific Flyway Support.1.2.3 Education and Research.

1.2.4 Improvement in Water Ouality1.3 THE NEED FOR RESTORATION.

1,3,1 Pacific Coast Perspective1.3.2 Southern California Perspective ..

1.4 THE GOAL OF THIS BOOK.

Chapter 2: Restoration Efforts on the Pacific Coast2.1 INTRODUCTION.2.2 MAINTAINING TIDAL FLOWS IN SOUTHERN CALIFORNIA LAGOONS

2.2.1 Differences in Tidal Flushing .2,2,2 Channel Characteristics and Aquatic Organisms .2.2.3 Relationship of Salt Marsh Vegetation to Tidal!nfluence2.2.4 Resident Salt Marsh Birds .2.2.5 Summary of Patterns Associated with Tidal influence ....2.2,6 Effects of Improving Tidal Flushing at Los Penasquitos Lagoon.2.2.7 Conclusion .............�,,

2.3 CREATING FORAGING HABITAT FOR THE CALIFORNIA LEAST TERN ANDLIGHT-FOOTED CLAPPER RAIL

2.3.1 Fish Assemblage2.3.2 Benthic Invertebrate Assemblage.2.3.3 Long-Term Concerns .

2.4 REESTABLISHING AN ENDANGERED PLANT IN SAN DIEGO BAY: Salt Marsh Bird's Beak ...2.4,1 Ecology of Bird's Beak2.4.2 Monitoring for Mitigation Requirements .....2.4.3 Implications for Monitoring and Reestablishment of Bird's Beak.2.4.4 Recommendations for Introducing Salt Marsh Bird's Beak

2.5 LESSONS FROM CASE STUDIESLos Penasquitos Lagoon,Warm SpringsBair Island Ecological ReserveHayward Regional Shoreline Marsh.Muzzi MarshHumboldt Bay Mitigation Marsh .Salmon River Estuary �.�Gog-I e-Hi-Te Wetland System ..Pacific Coast Terminals Salt Marsh Compensation

Chapter 3: Problems in Restoring Wetlands3.1 PROBLEMS DURING IMPLEMENTATION

3.1.1 Hydrology and Topography3.1.2 Substrates......3.1.3 Biota.

20212324

....,. 25273030

.... 31. 32

.33,30. 34

353637

.3738

, 39

tv TIDAL WETLAND RESTORATION

3.2 SALINITy PROBLEMS

3.2 1 Reductions in Salinity3,2.2 Increased Freshwater Inflow3.2.3 Eutrophication and Contaminants.3.2.4 Recommendations ..��,.�.�...,.....�,....�..

3.3 PROBLEMS OF URBAN WETLANDS3,3.1 Visitors.

3.3.2 Trampling .3.3.3 Lack of Buffers

3.3,4 Recommendations3.4 PROBLEMS WITH INVASIVE EXOTIC PLANTS

3.4.1 Adverse Effects

3.4.2 Conditions Promoting Invasion3.4.3 Deliberate or Accidental Introduction3.4.4 Invasions After Hydrologic Modifications.3.4 5 Invasions After Disruption of Substrate .3.4,6 Recommendations

Chapter 4: Recommendations for Improved Planning4.4 GOALS AND PERFORIVIANCE STANDARDS IN RESTORATION AND MITIGATION PROJECTS ...

4.1.1 Mitigation Issues Related to Goal Setting ........4.1.2 Goals for Restoring Southern California Coastal Wetlands4.1.3 Performance Standards

4.2 A REGIONAL APPROACH TO PLANNING4.2.1 Regional Losses4.2,2 The Need for a Regional Restoration Plan

4.3 THE TLIUANA ESTUARY TIDAL RESTORATION PLAN4.3.1 Management Needs4,3.2 The Tidal Restoration Plan.4.3.3 The Model Project4.3.4 The 200-Hectare Project.4.3.5 Restoration Research Needs ....................................................................................

Chapter 5: Methods af EnhanCing EcoSystem OevelopiTIent5.1 AMENDING SOI STD PROVIDE TALL CORDGRASS CANOPIES

5.1.1 The Importance of Organic Matter .5.1,2 Shortcomings of Sandy Substrates at San Diego Bay Mitigation Sites.5.1.3 Limited Effectiveness of One-Time Soit Amendments.5.1.4 Why Short-Term Fertilization Does Not Enhance the Nitrogen Pool5.1.5 Producing Tall Cordgrass Vegetation with Multiple Additions of Nitrogen5.1.6 Impacts of Nitrogen Fertilization on Insect Pests ....,...��...�...�,...,.............5.1.7 Recommendations for Improving Restoration of Cordgrass .

5.2 EXPERIMENTAL APPROACHES WITH MESOCOSMS5.2.1 The Value of Experimentation Before Restoration .5.2.2 The Tidal Mesocosms at Tijuana Estuary5.2.3 Determining Factors That Limit Ecosystem Development5.2.4 Consequences of Coarse Substrate5.2.5 Conclusion and Recommendations

5.3 ARTIFICIAL WETLANDS TO AUGMENT USE BY ESTUARINE BIRDS5,3.1 Construction of Shallow Wetlands from Upland at Tijuana Estuary5.3.2 Attributes of the Artificial Wetlands.5.3.3 Use of the Artificial Wetlands by Water Birds �...��.��...��,.......5,3.4 Conclusions

434344454546

....46

....47.. 48

.484849

�, 5050515252

54545556

, 606061

,. 6363

.64

.66

.66.... 68

6969697070

. 71.... 73��73

75.... 75.... 75

75

.�, 76

.... 77,.... 77.... 77.... 77... 78

.78

CONTENTS

Chapter 6: Improved Methods for Assessing Ecosystem Development

93979899

,100I01102102

Chapter 7: Adaptive Management of Restored and Constructed Wetlands7.1 THE NEED FOR ADAPTIVE MANAGEMENT

7,1.1 Rationale for Adaptive Management.7.1.2 Constraints.

7.2 EXAMPLES OF ADAPTIVE MANAGEMENT ..7.2.1 Sweetwater Marsh National Wildlife Refuge: implementing Adaptive Management ....7.2.2 San Dieguito Lagoon: Establishment of an Adaptive Management Restoration Plan ....7.2.3 Famosa Slough. Enhancement Through Adaptive Management7,2.4 Other Projects in Which Adaptive Management Is Necessary or Desirable

7.3 CONCLUSIONS

. 111121l22

References .Selected ReadingIndex

6.1

6.2

6.3

MONITORING AND INDICATORS OF CONDITIONS THAT SUPPORT BIODIVERSITY.6.1.1 What is Monitored and Why6.1.2 Indicators of Ecosystem Functioning .6.1.3 Testing IndicatorsIIVtPROVING METHODS OF ASSESSING FISH POPULATIONS6.2.1 Improving Quantitative Assessment6,2,2 Better Estimates Through Statistics6.2.3 A Proposed Standard for Estuanne PopulationsANALYSIS OF THE FOOD WEB AND FISH-SUPPORT FUNCTIONS .6.3.1 Technical Background6.3.2 Role of Detritus in Atlantic Coast Wetlands,6.3.3 Role of Southern California Salt Marshes in Supporting Fish .USE OF REMOTE SENSING TO MONITOR PROPERTIES OF VEGETATION

6.4.1 Applications6.4.2 Mapping the Areal Extent of Species and Assemblages �...,6.4.3 Assessing the Structure of Vegetation or Landscape5.4.4 Assessing the Condition of Vegetation6.4.5 Case Studies

6.4.6 SummaryADAPTIVE MONITORING AT TIJUANA ESTUARY: Assessing Interannual Variability.6,5,1 Physiography and Climate6.5.2 Adaptive Monitoring6.5,3 Environmental Change Within the Estuary .6.5.4 Recovery and Long-Term Implications6.5 5 Recornrnendations for Long-Term Monitoring .

. 81�...81

. 82.83.84. 85

858686

.8687

. 87

.88

.89.899192

104104

.105

.105.... 105... 108

108,. 110.110

PREFACEYI TIDAL WETLAND RESTORATION

PREFACE

Thii book i» an effort to iynthcsire knowledge and makescientifically based recommendations for irnprovcd wet-land management. It provides recomrnendationi for man-agement based on what I arid my aiiociatei at the PacificEstuarine Research Lalxiratory PERL!have learned aboutthe fuiiciioning i>f wetland ecoiyi ems, Studiei by manygraduate .iluden s and research aiiociates at PERL andfunding from bo h public «genciei and nonprof'it founda-tions contributed to thc information preien ed here.

My underitanding of reg>ulatory iiiues comes frominteraction wiih many excellen emphlyeei of the Califor-nia C<>«ital C<immissi<in, 1he State Coastal Conservancy.the U.S. Fiih and Wildlife Service, the U.S. Army Corpiof Engineer,, and the Environmental Protection Agency.IVlany of my itudenti have gone on to g>overnrnenlul poii-tioni or become environmental c<miultanti; I'r<>in them Ihave learned how important dec iiioni are ol'ten made withiniufficient scient ific understanding. I have alio benefitedfrom the views of public volumeeri. Southern Calif'<lrniaii probably unique in haviilg such a large number of citi-zen groups thar focus on their reipec ive nearby we land,for example, Friend» of Famos«Slough and the South-west Wetlands Interprelivc Associali<in. I have learned agreat deal fr<1m these dedicated citizens about what pe >picwan lroin wetlandi. My interactioni wi h icienristi around he world have provided many <opportunities l<> diicuii h<iwtriculturc and attitudesabout property righli ii riiotcd in thc rnidweitern fanningc<immunity where I wai raised. Ai a reiult of «11 heieinllueiices and interaclions. I believe 1 speak ai a practicalicientiir with a love <il the land and a itr<ing desire to sus-Iiiin Ihe earth's hiOdivcrsrty.

Thii preface pr >vi dei an opportunity to explain howthe wetland research program caine to he and to oNerthanki I<! every ine who played a role in iti development.PFRI. v ai ci ahliihcd in 1<!t�, when funding wai niadeiivailahl» lhy thc California Slate Resources Agency t<i cre-iitc I rcihv ater v et landi I'or habitat an<i outdoor rnesocoimil<ir rcicarch on abandoned agricultural land adlacenl toTi u«na Ei u«ry. A field research laboratory wai devel-oped on a 2h-ha ii e purchaied hy the S ate Coairal Con-scr< ancy for the Tijuana River National Estuarine ReicarchRe.ierve, with litle given lo thc City of San Diego. TheLI.S. Fish and Wildlife Service contributed tv'o surplustrailer houici that became the first "labs." We installediomc fencing, laid a v,ater line, ran electrical wiring to thesire. and had iigni primed; San Diego State Universityrcc<>gnircd the value of the acliviliei by making the labo-ratory «ii oftici«I unit <il thc Department of Biology andCollege ol Sciences. Interaction and communication be-tv 'een agencies and researchers have been close through-

iut ihe hiStOry i>I' VI-.Rl, <IVed

in iCtting up the iiiiiial l«Ciliry. Ai reSear h aC ivitieSexpaiidcd, Ihe name PERL aliii cxpan<lcd to nlciui the re-iearch group thai actively irudiei wetlandi. Juit I yearilater, the San Die C<iuncil dc<. I red Pf'RL Day onJuly I>. I'!92, in recog»itioil iit icrvicci provided to the pub-liC. eipeCially inl<irrna i<ill I'el<'.v lilt t<'> hL' Il'ian'<gL'Iri<'Ilt OlTijuann Filuary.

I liiving direc ed tile }!A>up iulL'L' ili ale<'pti !n, I anlin debt to hundreds of people v, lio believed iri the imp<>r-tance of science-baied dec iiion nlaking; wlio iikcd t'or «d-V iCe; <Vho wr ite let1eri i>l' iupp >rl 1 <ir iur rCiC«reh prOpOi-ali; Who eiiL' !<<>aged ni were rejected; who held a shovel, ret'raclomeler.or chpb<iard: whi! In<<oned tiih '<c ines it<id co in'teel plililt'i:who probed illud iamplei t'or micr<iicopic lx:aiti; who ipcntlong houri;It thc coiuputcr making sense of mud-ilairieddata shee i; whf S<luthernCalifornia'i coaital wetlands. In deep grati udc, ldedicatethii b<«ik to all for their help. v, i h ipec i«i thank» ro th<liewho have continued in careeri uiing wctliind science tiiimpr<ive the managemerl <il'natural rCiOurCei.

Thc mainstay of PERL'i reiearch I'unding baic haibeen the Cali 'omia Sea C>rant College Syileiri. WhenTijuana Eituary v sii deiignaied a naii<mal reserve, the Sanc-tuariei and Programi Diviii<in of the Nalional Oceanic andAtmoipheric Admiiiiilrati in I NOAA I added reiearch andnionitoring fundi for work at that iirc. The I!.S. Fiih andWildlit'e Service now rhc Na ion;d Biological Scrvi«cl es-tablished a cooperative agrecmcnt rha provided e<luipmentand reicar heri to aiiist with reitorat i<in rcicarch. NOAA'i

CO«ital Oceair Pn>grani i ippOrted CO<nplemeiilary studiesol'wayi 1rial itin C«ltrans! iupporlcd tnonil<>ring work at San Diego Bayand facilitated research a the department'i mili «li<in site.Loi Penaiquii<>i Lag<xin Foundaiion and San Diego Countyfunded moni1oring ot lwo coaital lagoons norlh ot SanDiego, b<>ih f'<ir the purpoie of understanding problernicaused by closure of iicean inlets. M;uly of he researchgrants have requiref Sciericei an<IDepartment of Biology at San Diego Sra1c Univcriity.

Reviewers c<intrihuted iigni ficantl y to thii c Tort. Thccontriburors and I are gratclul to Si Simenitad. WayneFerren, arid J<ianne Kcrbavaz for their time and thoughtfulcriticiinli. We are grateful tr iupport of thii publication, and especiallyto Roiemary Amidci, communicat<Oni c<«irdinator: Bar-bara Hallihurton, copy editor; and Joann Furse, for desk-top publishing.

Joy Zedler, PERI, Director

CHAPTER 1

Pacific CoastEstuaries and Wetlands

1.1 INTROOUCTION

age is uncomrn<m.

I'he U. S, P<icific Coast parallel» a major mountain chainand a steep continental shell. Water»beds are small andclose io thc coast, witfi wo conspicuous excep ionrc thoseof he Columbia River and San Francisco Bay Figs. 1.1Aand 8!. Coastal streams are numerous more than 100 inCalifornia alone! but rarely extensive, Rainfall is highlyvariable, both tempnrally and spatially, in many coastalareas Fig. 1.2!.!Most of California is characterized by a"Medi erranean-type c! imate," with warm, dry»ummersand cool, rnnist winters. Summer always includes a pe-riod of little <ir no rainfall Fig, 1,5!, Even the PacificN<ir hv< e st experiences sum incr d rough . Thenoncontiguous sta es have climatic extremes, with shor-tene gr<iwirig seasons and colder temperatures in A! askaand tropical hear and high year-r<iund rainfall in Hawaii.The diversity ol'estuarine ypcs within the Pacific statesis high, because ol' both phy»iographic and climatic v ari-ability � for example, fjords in Alaska; mangrove-d<imi-na ed sites in Hawaii: major bays in Puget Sound,Humboldt Bay. San Francisco Bay, San Pedro Bay, andSan Diego Bay; and in crmit cn lagoons between theselandmark bays Despite their northern latitude, few ofI.he Alaskan est ares freeze over in winter, so ice dam-

1.1.1 Comparisons with Other CoastsOn the At!antic side of North America, the United Statesspans a natrov er latitudinal range than on the Pacil~c,and the coastal tnpngraphy is much more gent! e Estuar-ies in the East. have been studied touch longer than thosein the West, because estuarine science devel<iped on theAtlantic Coax . Until recently, an en ire scientific jour-nal, t hes<zpe<tke Science, was devoted to studies of thclargest and most va!ued U.S. estuary, Chesapeake Bay.The broad A lan ic coas al plain has many large water-»heds, and most of the rivers have continual inflows offresh water, because summer rainfall is ample. Together,the large watersheds and year-round precipita ion pro-duce the "textbook estuary": one with a gradient nf sa-linities froin fresh to marine, a rich complement of or-ganisins that are adapted to brackish water, and highly

PACIFIC COAST ESTUARIES AND WETLANOS

produc ive tidal marshes tha export substantial quanti- ics of pari.icula e organic niat er to nearshorc waters andprovide the food base for large numbers of cotnrncrcialfish species.

The U.S. estuaries house large areas of in ertidalwetland, but the East and West coasts differ in habitatdistribution. Acc<irding In Field ct al. �991!. the con er-rninous Uni ed S a es has more than 1,6 inillion ha nfcoastal salt marsh, of which only 3/r occurs ahing thePacihc Coast, Tidal lla s c<iver a smaller area nationw'ide

approximately 0.5 million ha!, bu he Pacif i c Coast ac-counts f<ir ! 7~/r <if Iha to al Table 1.! !. Thus, Pacificinter idal habitat» arc less vegetated than those along ei-ther the Atlan ic or the Gulf coasts. The Pacific Coas has 1.64 times as much tidal f!at as sall marsh, coniparedv ith a ratio of 0.24 for lie rest of the conterminous Uni edStates. No doub this rcBects the gcol<igical!v younger,morc tectonically ac ive, and steeper Pacific coast!inc.

1.1.2 Tidal PatternsTwice a day, ocean waters en er and !cave thc idal wet-lands along the Pacific Coast. This pa tern is a semidiurnaltide, in which thc rising or flood tide is follnwcd about6.2 hr later by a falling or ebb Ii<k. California's coastexperiences "mixed scrnidiurnal tides,' that is, a com-piex tidal pa tern with wo high tides per day that areunequal in heigh and t<xo low tides per day that are a!sounequal Fig. 1.4!. Each day, the higher high tide <iccurs50 min la er in the day than the day before. Spring ides those with greater amplitude! occur when thc forces ofthe sun and moon act toge her and a!ternate wi h neaptides, which occur every other week v hcn the gravita-tiona! forces of the sun and moon opp<ise each other. Fora comple e discussion of tidal f'orces, see Defant 1958. }

In Southern Calif'<irnia. he highest tides extremehigher high water! are about 7.5 fi �,3 rn! above thercferera e datum mean lower low water = !!: mean tidalamplitude is ab<>u 3.9 ft ! .2 m!. and mean spring tidalamplitude is about 5.6 ft �.7 tn! NOAA 1995!, It isusefu! to summarize tidal da a on a monthly basis to sh<iwthe extretne high water. he mean higher high water. andthe number of times hat tides exceed i arious elevatinns

Table 1.2!.

2TIDAI INETLAN0 RESTORATION

A

SkagitHood CPugetGrays

Wit!ape BayColumbia RivNehalem RiveTillamook BayNetarts Bay

Sitetz BayrYaquina BayAlsea RiverSiuslaw RiveUrnpqua RivCoos BayRogue River

10

v'X

IVV

Size km !KlamathHumboldEel Rwer

Watershed

TornaieDrakesCentra

San FrEikhor

y

Mission BaySan Diego BayTifuana Estuary

Figure l,l Wect Coast watereheds. A Estuarine drainage areas of the Paoifio coast of Ihe conterminous United States. Areas are tower partsot I"e watershed Ihat drain direotly intO eStuarine waterS and have the greatest human influence From NOAA 1990 B Sizes Of coastalwatersheds in Cakfornia. Data from Jacobs et al 1993

2.0Ec>

C <d L 10

ed< >

0 0

g 80

<e> 60

P 40<b

o 20

0 1-10 11-20 21-30 31-40 41-50 51-60 61-70Rainfall per water year lcm!

Figure 1.2 Histogram of rainfall at San Diego ILindbergh Field!over a 140-year period. Water years are October 1 throughSeptember 30.

0 2 4 6 8 10 12 14Month

Ffgure 1,3 Mean rainfall per month for San Diego Lindbergh Field!for 1850-1990. Bars = SE.

In Decclnhcr, the mean higher high v a or is maxi-mal; in March. i is minimal. Fcw high ides occur inMarch. Several aspecls of this tidal patternhave specialsignificance for wetland biota. Sall marsh algae and vas-cular plan s are highly dependent uri tidal inundation. Itis clear from their phenology that the vascular plantsdepend on tidalwatcr for moisture. They grow activelythrough summer when Southern Califoinia has no rain-fail. In irnmcdiate contrast, he plants of the adjacentupland are active in wint.er and dormant in summer, asis the coastal sage scrub and chaparral of this regi<in. Atthe wetland-upland boundary, Srzli< prnia subrermi nali 5 a v etland obligate! is active in the sutnmer, whereasLy< i urn cahforni< urn fan upland shrub! is dormant. Thesetwo plants often grow side by side, bu they obviouslydiffer in their water sources, with S. subfermi nuiis ableto tap into saline groundwater during the long, dry surn-mers.

Marsh vegetation grows most actively betweenMarch and 3unc Wintie!d 1980!, perhaps in responseto increasing length of day and warmer temperatures,

PACIFIC COAST ESTUARIES AND WETLANDS 3

hui ihe day lime low ides in spring li ig. 1.4! should actsynergisiically io wan» soils «nd s fmulafc growth ofroots and rhizomcs. The light-f»oled clapper rail Rallu.<Irn <'ir»xr> L< !ei'ipe>! appearx 1O taLe advant.ige Of' thispa terri hy huildin i i» ncsls iri he lower inarsh begin-ning in February <>r iVlarcIL h'osis are least likely o beinundated iu th» ime IZed}cr I <!93!. Macroalgae growrapidly in ihc spririg. v he» dayiinie low ides providemore lie>hl I kudnickl 1986!.

In the I' ill, low li des ocr:ur durin the late afternoon,whereas iri he spring. 0le lowest lides occur al night,Low tides during ho al'ternoons lead to warm and hy-persaline niarsh soils. When the nex tide covers themarsh, the waler absorbs lhe heat, and channel watersand associated fauna are warmed by the ebb tide, Water emperalureS are greatest at this inle, in pari because Ofthe 1<mg exposure lo sunlight bul ale<> because of watercontact with warm marsh s<>ils. I'his may be one reasonuse of lhe region's in crtidal marshes hy fish is limited,PERL has begun con inuous monitoring of v ater salin-ily, temperature. pH, and oxygen at Ti juana Estuary, s<>that these Iong-recognized patterns can bc documented.

Because tides have such an enormous influence oncoastal wetland hio a, the need is grea to understandfurther the dependencies on and lo!eranccs ol' lhe lim-ing and duration <>f tida! inundation and exposure hydroperiod! of various species. Because of the sea-sonal and daily variations in hydroperiods, this is no asimple ask. Most of our understanding is based <in com-parisons between si es with a long history of good tida!flushing and sites v ith interrupted tidalaction. TijuanaEstuary sec ion 1.1.3! is a good example of the formertype; it suppor s rn<>re rialive species than less tidallyinBuenced systems section 2.1!.

1.1.3 A Satttple Pacific Coast WetlandIn San Diego Couniy, the esluarirte "type specimen" isTijuana Estuary, and conditions al his tidal system il-lustrate the environmental fOrCing functions that con-trol the biota. Tijuana Estuary flat 32 34'f<I, long117'7'W! is the soulhwesternmost estuary of the conti-nental United States. Because of' its location un the tec-tonically active Pac if'ic Coast, it has a dynaniic geologicsetting. This drowned-river- ype estuary is small �24ha! compared with river mouths along the more gentletopography of the Atlantic and Gulf of Mexico coasis.Its river II<xxfs only during years when large winterstorms occur; even then, il is virtually dry during. sum-mer.

The 448,323-ha watershed is mostly �3'/r ! wi hinMexico. Together, unc large reservoir. behind RodriguezDam on Tijuana River, and two sina! I U.S. rcscrvoirs onCottonwood Creek, con rol 78'7< of the watershed up-slreanl of Tijuana Estuary. Situated 8 km upstream ofthe estuary is the mctrop<>lis uf Tijuana. Baja

4 TIDAL WETLAND RESTORATION

Table 1.1. Comparison of Salt Marsh snd Tidal Flat Areas in the United States, by Region

AreaRatio of TidalFlats to Salt MarshTidal FlatsSalt Marsh

Acres Ha

Region

Acres

0.30202,550500,500�42,800!�56, 100!�01,600!

668,515AtlanticNorth At! anticMiddle AtlanticSouth Atlantic

1,65 I,900�8,100!

�89,600! 894,200! 0.20

205,382 0.20507,500Gulf of Mexico 2,496,600 1,010.360

1.6480.979200,100�S,200!�0,900! 93,900!

49,332PacificWashingto~OregonCalifornia

121,900�8,300!�3,200! 90.900!

Total for Nation 4,270,300 1,728,1 67 1,208,000 488,871

Note: Numbers in parentheses are subtotals for subregions. Acreage data from Field et al., 1991.

Table 1.2. Number of 1990 Tides Predicted for San Diego Bay Broadway Pier! That Would Exceed Selected Elevatlons

Exceed Each DatumEHW cm!

~f 50 MHHW r4.9! cm!

Itbfe: MHHW = mean higher high water, 6 HW = extreme high water.Data summarized from National Ocean Service tide tables from Zedler 1993!.

L'aliiontia. a growing city of about 2 million inhabitants,Between Tiluuna and the estuary i» anurbanized and agricultural river floodplain with nopristine habitat.

Southern California has a dry Medilerranean-typeclimate, with mild, wet v, inters and warm, dry summers.Annual rainfall i» usually low, with an average of ap-pr»xiinately 25 crn <m the coast Fig. 1.2! and 50-100crn in the surrounding source mountains IPryde 1976!.The average miinthly temperature range is on!y from9-21'C' t4g'--69'F. NOAA data for San Diego!, and av-erage daily solar insolation is I 7'-61� iangleys Taylor197!t!. Frost is extremely rare along the coast, and snowis vinua!ly unknown. However, although temperarure ispredictably moderate. rainfall and streamf!ow are not.

Number ofMonth «210

i 6.9!Jan 5Feb 1Mar 0Apr 3May 5Jun 6Jul 5Aug 3Sep 0Oct 3Nov SDec 7

Tides~f95 ~6.4!

12

3 3 5 6 71211

5 81213

Per Month Thatifa0 ~165 ~5JI! >5.4!

15 1915 249 257 17

13 1815 2117 2216 3121 3217 3018 2420 24

26 17930 17432 16328 16823 17225 18433 18436 18139 18039 17925 18428 188

226210201216229232232219198213229238

Neither the ainount of treshwater inflow nor its timing isdependable.

Precipitation data suggest that rainfall increasesgradus!ly from October lo a peak in January and Febru-ary and then gradua!ly declines through April. Averagesare misleading. however, because a single month mayinclude much of the year's total rainfall. In December1921, rainfall was 24 cm, nearly equal to the annual av-erage, The month with the most variable rainfall is De-cember standard error SE] = 0.4!; the least variablemonth is June SE = 0.2!. Rainf'all da a are bet er charac-terized by modes and measures of variation than bymeans. For 134 years, the "modal year" had less than 25cm of rain, and only 22 years were within 10% of thcaverage. The coefficient of variability for annual rainfall

PACIFIC COAST ESTUARIES A!ID WETLANDS 5

OPIIP

D ICI«1.«1.

O IPPICP

CP

I«I

P

E

0!Ch1

C«1

O

CIZ Ill

C O CIIO tll�

I

= =J

CI

IO ICh0>

1

QICl

Cl

C ICC

I

CPIIC.

'D I 4 CI CI Ct

IO ICI V CI CP CP ICP CP

O

CIO Ig«0

O O.O-

J:«PP

D O ICCPOJ:OICI

O

D Ill

0 O I/IKE

H ICO I/ICIIUl

» 0 1 </<; the SE !s l.'!; the r;mge is 1 � 7 ! crn. Because of hese high interaniiualvaria iOns iii lh« tiining and in <ital am<nint <il' rainr'all, ihe pOtential f<ir variatiOns ins reamfl<iw is great.

Na ural s r«amtlows 1<i Tiluuna Estuary are modi-licil hy R<i<lrigucr Darn; n!ui!!cipal discharges of im-pone<f Water io he Tijuana RiV«r, n»isily in the fi!rm Ofrenegade sewage flows I'rom Ihe C!ly <il 'I'ijuana cf.sect!on .1.'!;;uid hy agricul ural runoff. Streamll<iw isvari<!hi«WI h»'I n!<inths. Witl92 sliindard Crrurs as high av.!S n!illi<in cubic in«ters", ihe I«ast v;!nable months areil»isc with l<iw s re;»»flow. Seas<inal 1'l<iws 1 ad to highio ra-;»!nu<i! var<nb!liiy; y«ars of l<iw rain 'all have littles rcan!fhiw in Ihe winter and li tie difference inv lean!flow <<in! fnonlh o mon h.

1ijuan;I Estuary <s In flu«need by a«midi urn a I mixedtides. Appr<ixima ely S !'!< ol' thc t!daf pnsm the aver-ige v<ilume iif water exchanged by the tides! is attrib-» 'dlle I<i hc northern arm Oneonta Slough! of theestuary Willi in! s aii<l Sw inson I <!t�1. 1 t is < iric air pho-tos lniin I'! Io Ihe pres«n ! show ihat al1h<iugh theniaii! ch.'ii»iel h<v been at!ected by wave washovers i»!d<'hi<'I<.' c'nisi<<», thc an»Ill«rch'1!!nc'14 '<!Ed !dill ci'ceks h'!ve

«i!»i! g< d li�1» /c<f ler et al .. 191 E I. M«an sea level rises.'I i<!<il 2 I ci!l/c«nl<»'v i<1<1»g the San Diego shore Flicka»d Cay;in 1<!r SI lhiwever, during the 1981 El Nirlo.rhc avc! agc sc.i level w«s I s cni higher Ihan predictedi R. 1'lick, pi rsoo;<I c<!n!muni«ation 1 and storms furtherr,»sed vv;I «r levels.

I I s i! I! ! I! 'I a I' y, 1 I ! I V>le»is a h!v ory ol hy<frufug!C mOdif!Ca-li«»,lad liu»E»i«<le»i;Iel!»E<.'I The Con!bina !On Ofnatu-ral .I»il <ir!thr<ip<ig«nic <f!s urh <nces is un!que for each«stu;Ir> a!!d Iagii<ii!; henCe. ri<i Wo Coastal Wetlandx arebiol< igically id«iit ical Rather, a spec run! <if condiiior!scx!v s, fr<i!ii less 1<i m<ir«disturbed, and he differencespnivide a g«n«ral un<fcrstanding ol' which species aren!<ire <if«rani;ind w!despread. and which are more sen-sl!ivc and more restrictive in 1heir OCCurrenCe,

1.2 NATURAL FUNCTIONS AND VALUES

Whirl;In e»uary dOes Consii utes i S many funCtiOnS.Estuanes are responsible for the primary production Photosynthesis of both vascular plants and algae! of

materi,!l Ihat lu«ls t'ood cl!;Eius. li! addi i<!i!. licse svs cn!s occur In shel crcd areas th.!t ue !ttracllv« feed!I!Lsites f<ir both tish <ind birds and thus functioii as refugesand nurser!es for select<»1 sl!ccics. frinaffy, tlieir ei»crgent wetlands filter sedin!ents ai!d nutri«nts tronE hcwatershed, st»bi fixe shorelines. »n<f serve as buffers v henflooding occurs. 1'hose functions !he public c<insidersbeneficial are its v;!lues. Thu».1he pr<iduciion ot salrn<inis a value, whereas lhc r«lease of dihydr<igen sulfide <idorof r<itt«n «ggs! is ni!t. Neither hc functions m!r the val-ues of Pacific Coast wetlands have been adequately as-sessed; however, iheir role in support of fisheries andthe Pacific Flyway has been investigated.

1 2.1 Fisheries SupportThe term estuary is af!nost syn<inymous with co«stal fishand shellfish h;ibit;it in the Vnited States, and most of'the nation's legislati<m c<incerning coastal Eve lands andestuaries is geared tov ard t'isheries management. Yetmany PaCifiC CO»Stat eStuanCS are <!<i sn!afi tO play adominant role in fisheries support. Coaxial upwellingsupports the plankton-based food chain along Ihe Pa-cific Coast, with relatively minor contribu ions of d«tri-tu» fi'Orn Coastai marSheS. ACCOrding h! MCH»gh �976kestuarine-dependen 1'isheries accoun ed for 54'lr iif the

Washington catch and 37% of the Oregon calch, but only3</< of th«California catch. llowcvcr, Onuf andQuammen �985! sugges1 that the California contribu- ion is diluted from perhaps 7</r, because Mexican-caughtfl! sh are included in the data on Calif<imia port landings.

Still, the estuaries provide critical habitat for a num-ber of fish and shellfish species. These include salmon coho, On horvnr hrr.i ki sar< fr; churn, 0 kera; chinook,O. r!hu«vrs<'ha!, Cal!fornia halibut Paraii<iirlryi< uli fvrrrir us!. Dungenevv Crab Cai!< er ma,",i Srer>, PaCitiCOyster Cr <rssusrrea eiguS, intrOdueed frnn! Japan!, andclams littleneck clain, Pr<!rorhu< a sramrrrr a; butter clam,'!arid<!nrrri gi gurrrerr<; Soft-shelled Clam, ME<i err'rruri<r,introduced from the East Coast!. The highest catches arcalong the Pacific Northwest states. On the basis <if' heirshort-term use of estuaries, sockeye sahnon O. nerku!and pink salinon O. gorhrr <ciru! werc not considered tobe es uarine-dependent by Onuf and Quam<nen �98S!,although both starry flounder Pluri r hrirys sreilarus! andEnglish sole P/err! oner res verrrl»s! were consid«red goodcandidates for estuarine dependency. ln Califon!ia'sMugu I agOOn, shovelnosc guitarfiah Rhinahara<prrrdrrrrrrs! are summer reside» s, and in Elkhorn Slough,leopard sharks Triakis semi'fus<'iara! and bat rays hfylioburis cuiifarni< a! are caught for commercial use Onuf and Quamrnen 1985!.

lr! summarizing he fish support function of PaciticCoast estuaries, Onuf and Quan men f 985, p. 12'!! con-cluded, 'Wetlands here do not yield f<E<xt chain suppor by sheer mass of organic matter produced. as they mayelsewhere. instead, food chain support arises froin the

Live !I ih<.' «c>l UIds i>1 spec!L!l «;> s liy tlic oi»i«ol afl,'«vliick s .. I aid 'hair s ipp irt Ls i! it <!i>ectly 1!cd t io! 'I" ill pri»>ar pi<iduci!vi>y it r lie w etl.iiid .. I'rcy <e-lect! l>y s»gg<'sl s >h.il q l illty or !v,'>>I.>I!!br ! Is»«ii!c U>1-p<lit l»rib »1,1»>i!Li»t. I I ress I/roi< nr !!r»r I!r<rr li<ds lil>hc sh JIIle!'s '!lid c»1<,'I'gc»1 hei'<'tiillo11 .� iilu tid ilcfi;cks <ci i c;It,ii c sub tee'I lo pic-<lilil i I . A Sill�> '�s>iid, lie! >o»'l l C il»111 li'iic.it«i» 1,

1.2.2 Pacific Flyway Support%1;»>y types iil v;1>cr-assiic i«to. I lic iii irshcs Jnd;Idj;>CC»t l>iil»t;irs serve «s n>igr,»Ory stopo ers,ind,>shrCCdi»g Liiid «iiitering grOur!<ls. Tl>e in<is1 num r<iuSbirds;ire watcrtii« I, «'ith shorehirils scconil. Onul a» tQuoi»!»ei> I iqf S> i«itc that n>ost iit' thC I',ieiliC «�iter-lov I v Il>tci' li! il tii> I!li> s C curl"d Valilcy. AI !ng lh 'co;!st. sl>oi cliirds d i>»ii>aic ihc use i' intertidal tl >ts and»i«rslics. il>lu!ugh ducks, geese. ciiots. gulls, and heronsJre i!lao C<!»U» ii», Wcsterri sandpipers C,<ill if>i m tirl!,du>i h» f . dow i>Chers Lr'!!I!I ! lr>!!!r»» sppi k«nd An>eriCan av<ieet tk ririi I !srr > unr rii Unu! arC;>bUI>d >1 ii> >u Ill its IQU«n>n>el> I<!>�, I !>141.

Liftorts arc uiidcr «siy by thc I'i!i>i> Rcycs I31rd Ob.scfv'it lry St I>son I3c, ch. C;>fifo!T!ii! 1 io cc�sUs 1>ll «i.'I-lands»> ll>c I'ii i! ic l ly«iiy fi!r thc support <il shorcb>r<fs,Vrelin>in;iry result< iiidic;i c tl>at shiiriebir<ls c »icentrate in ii fcw large «,c>l,i»ds, i» ludin Ihe C<!ppcr a»d S>ik incRlvcl' deli is i A I'>ski!, the I'I'ascr River deb;i in Br>tishC ol lli>bi.' , vs I I;ir bill Jrid W ill JpJ l3'>v In W >sh r>g-I il>, Ihc OIL»i>hi ! Ri!cr est u«fy,;ii>d S il> Frar>cise<ire than l X!, XX> bi»Is..'V];U>yother' c !Jstill J»d I»I J»d «'ell;U>ds .'»I'>tribute to the net-work ot s><!povcrs used hy shi!rcbirds dunng sprmg andI' ill r>iigr;ir i<in ,

Although thc sh ircliirits, gi lls.,ind hel II>s h'ivc I»!direct con>nicrci >l value, Ihcy pnividc substa»t i«I rccrc-at>»» fol .'> go!«'ir>g»i!nil!el' Of Ou>LI i<!l Jet iv>ILCS, espe-cially bir<lwatching, s" atuic Jppre iat«ni has been val-ued at s! I.II hillii!ri/year ir> C ilit'i!rnia $1'!9. III per per-siin. Or 7 /< morc Ihan thc nati<in;il «vcr«ge; Duda 199l >.

1.2.3 Education and ResearchFour Pacif'ic estuar!es are included in the .'i«>ion«i Es-tuarine Rese«rch Reserve program: Pad!if«Bay in Wash-ingti!n, South Slougl> in Oregon,«nd FikholT> SIOUgh andTijuana Estuary in California. Bach sire is resp insiblefor c< in duct >ng educ at ion J I programs, interpreting thenatural resources I'i>r the public e.g., S>lberstein and . ainpbell I 9II9! and otlenng resean h opportunit>es e.g.,'Ledlcr ct al. 1992! t.

Additional sites are also important for teaching andresearch feature interpretive centers Jre appearing inrn«ny publicly owned reserves e.g�Sweet«ater MarshNational Wildlife Refuge on San Diego Bayh Some ofCal>fornia's more studied wetland ecosystems are found

PAGIF>C COAST ESTUARIES AND WETLANDS 7

in S'>n D>ci' i P»iy', i>l p»>ter>'I M'»'sh, 51Ligu I Ji!<!o!i.1'.Ikhiim Sliiugh. autorr» Bay. S.'in Fri>ncisci> I3;>y. Bodcg.>Bay. B ilinas L g»on,;ind Tiin> iles B:iy.

1.2.4 Improvement ln Water QualityAltlni>igh >n>pre»t iri w;>ter quality is «n in>poitantfunctiiin f<ir n>liu>d wctilai>ds w ith dii vnsirc;m> «atci us-ers, Ihe ren>»vi>I of sedil>1e>rts U>d»i>tr>e»ts ffon> W«1 'Iflow ing thr»ugh I'.«>f ic estuaries is <it tcn considered les<v'ililiiblc Ihan I c»1 i ,ll in Lire is that have d<iw»slreainuse> if the Il»v,'U!g « Liter As s ilii>C w itcr !s little use t salt pr<!<tucti<ii1 is iir1 except �» I, thc n>'ll» w'>ter-qu;IlityC if>eer» is CU>l'i!phlcatl ili »I p illut ioii iil' Ihe OCean bynutr>er!ts. H<iwcver. the P«c>lic Ocean is considered i>u-tricnt lir»i>ed. sg rareevents, reducing b<ith thc potential for si 'riit'<cant rem !valJI>d thi.' ah!llty 1» nieasuri.' ». Also, lhe steep slope «ndnarro«conti»er>1«l shelf' reduce ihe p<itential tor accu-»'!Ulat I<!I> 'II !<cd»i>i. »Is. Sedll'>!cnt I>CC>il»L! I'>linn >.'i nnt Jprohlein I'<!r thc i!pen coast, bec«use bc«ches are ol'tensedin>ei>t st;irvcd. Where sediments are J probfein is ii>the co«stal lag<a!ns, v herc they reduce tidal pr!s»!s «nd1!dJI action. Fof c<J»!!pie, .'Vlugu Lagoon 1<!st 4 ! X of itslo«-ride volun>c during thc Il<i<ids if I '�13-19II ! O»UI'l >137! Rather thur> being perceived as an impnivcnientin wuter quality. «ccurnulation»l' sediments in coastalwetlands is considered an adverse attribute tor resourcemanagement. The pri!cess is I natural one, but the ratesh;ive beer! greatly accelerate t hy tw i modil'ications,' th construction iif r<iadways e.g.. Pacil'ic Coast Highway Iacross wetlands, v:hich deere iscs tidal sc<iur and trapsinflowing sediments, and increased erosi<!n >n coastalwatersheds, which results from intensive developmentand agric ulture.

Removal of co»t«min«»tv and pathogens by coastalwetlands is poorly known, but these issues make head-I»>es ln regions whel'C t»uriSI» >S in!pnrt Jnl t<! theeconomy. E Crt a!nly, opportun!ties eXist t'Or us>ng CO«St«lfreshv «ter wetlands for vastewater improvement, asshown by the success of thc Arcata treatmerit wetlandsat Humboldt Bay in .'No>them California Gearheait etal. I91331, Here the secondary effiuenr from a treatmentplant passes through shallow-v uter habit«tv that support

8 T!DAL WETLAhto RESTpt!Ar!ON

wetland vcgctati<in and attract waterfowl, jiigging ir iilsand bird-viewing blinds taciliiate nature appreciaii<iri.

1.3THE NEED FOR RESTORATION

The need to restore damaged and degraded ecosystemshas received nutiiin a! attention. Thc National ResearchC<iuncil �992! rec»nimended thai a national aquaticecosystem rcsiiirati<in strategy bc devel<iped for thcUnited States. Among ihc elements pr»posed were; Tha goals be established wilhin ec<ircgiiins areas withbroadly similar s<ii is, relief, and dominant vegetation!,'that g<ivern<nenta! agerlcies redeslgli !io!icies arid pro-grains to cinphasiz< rest<!r;iti !n, aii<1 hi<i inni!vativen'1easules iie Used ii! tluiance rest<!lit!i<ill wurk. A num-ber ot spccilic sllggcsiioiis werc illadc tii i»<ivc wetlandi'est<!rail iii fi o111 <I trial-a<id-cir<ir pn lccss to .'i pli:dlc-tive science, Whi!c i!<i iiational rest<iraii<in pr<igr;im hasbeen established, thc level »f interest has certainly beeiiraised, and the Naii<aial Science F<iundation n<iw has acon!pet<tive grants program in conservatiiin and resiii-rat 1 oil.

1.3.1 Pacific Coast PerspectiveRestoration <if estuarine wetlands is a high priority inmany regions <if he Pacific Coiisi. because so little ofthese hubitais remain: he are;i of wet!ands was ne~ergreat, and a high percentage <ii historical wctliinds hasbeen l<»i. Acciirdirig to dat;i cited by NOAA �990!,<Jt!'X ot C:<Iif<irttia's ciiasi;il v ethinyl;icrc.ige hiis beendesir<ivcd since sett!cment, Abiiut halt thc rcinainingcirisial wet!all<is in C ilifornia <recur in San FranciscoBay. Rcc<irds ciii»piled by ihe U.S. Fish and WildliteService Dahl ! <!9 l! for coastal plus in!and wetlandsindicate ihat Alaska has ihe nation s lowest rale of wet-land loss t�'i< !, whereas Calif<irnia has the highest ii !: Washiilgt<ilt !las li!si I 1 ii . Oreg<!n <!t'i<,;<ndHa<vaii 12'ii, Thi.' ciilllbincd 1<isa iif 1'rcsh and salinewct!ands is n<i diiuht responsible 1'or l<isscs iif'avian re-

sources and reduce<i cia<ala! water quality especiallyc<inta<ninants!. 1 he Calif<irnia c<iast has experienced ahigh loss iit' hi«livcrs<ty and <s undergoing severe de-vc!<ipmeni prcssure. Restoration efforts are thus badlyneeded.

Atter a br<i;id-based review of the status of aquaticeci'isystenis. Ihc National Research Council �992!ca!lcd for 1 milli<in acres � !f!,00t! ha! of wetland to berestore ii restoration <if the nation'S hiS-t<irical wethinds acre'<gc. 11' ! 0'ic i!f the wet!and arealost in Calif<irnia were restored, it would add about455, XX! acres t ! 8 i,o � ha! . This would double the cur-rent aCreage.

Pacilic Coast prob! ems and iieeds are not easily satisfied by p<ilicies tor resource management that may

%<'ll'k cise<<herc. P;irticip<iiiis in;i synip<isiiim to deter-rnitic research needs, held at the 1'!91 1'stuariric Research1'ederation, agreed ihiit pacific c<>as a! wetlands hiivcunique fe'iturcs ind that rnanagcrncnt va!ues and meth-<ods must hc dcveliiped with those features in mind Wil-li ims and /cd!cr 199 !. '1'his regi<in;il dilterencc v as alsorecognized in,> hniadcr rcvic<v by thc Naii<inal Rcsc;<rchCiiunc i I I <!9'i !.

1.3.2 Southern Caiifornia PerspectiveThe Southern Califiirnia coast has man> t'ca ores thatmake it use ul to ihc analysis of coast;ii wetland restora-tion problems and s<ilutiiiris: a high rate <if wetland io'i'i,a high and ever-increasing population density. nian> kin<laiil impacts <if devel<ipmeni. aod <hicurnentation of vari-iius efforts to restore dama 'cd wetlaiids. Hist<>rica! l<issesin Southern Calif<irnia's coastal wetlands and imgiiingdisturbances related iii the urban l<ications of the wet-lands have made these ecosysterns as threatened as theendangered species they support. Souther<i Cali 'ornia hasthe nation's m<ist densely populated estuarine drainageareas San Pedro and Santa Monica Bays, l NOA A ! 99 !] !,Tlic region began io gr<iw rapidly after World War ll andnever stopped. Between 1987 and ! 9t 9, approximately87,0 X! pe<iple moved t<i Saii Diego each year. M<ire re-cently �991 � ! 994! gr<iwth has been approximately-17, HX! additional residents annually.

Ehna Mac<hinald 199 !! indicate that the resourcesthat have been lost in S<iuthcrn Cali ornia coastal v et-I;inds are primarily shallow-water habitats. that is, saltm;irshes <md intertidal Bats, rather than the subtidal fishhahitats Table !.3!. Each of the region's 29 rcmaimngc<iastal wetlands Fig. !.5! has many unique features Purer ! 942: Carpelan l<�9; Frey ei al. 1970; Speih etal. 197 !; Bniv ning aiid Spcth }973; Mudic ct al. 1974:Macdonald 1976a, 197fih; Mudie and Browning 1976:Speth et al. 1976; Ferren !91 S; Onuf 1957!. Manage-ment issues arc equally diverse; they include concernsabout how to maintain regional biodiversity, maniigewastewater inil<iws including urban runoff!. mininuzceffects of sewiige spills. reduce effect» of' <mgi>ing hu-man activities, prevent algal hi<aims and fish kills. re-store damaged wetlands, and mitigate damages due tofuture disturbances,

Restoration of Southern California estuaries is a highpriority f<ir both the resource agencies and the public.The California Fish and Cam< Cominission has calledfor a 50ci< increase in the area of wetlands statcwi<le StateConcurrent Resolution N<i. 28, Sept. ! 3, 1979!, and arecently formed citizen group, Save Calilomia Wei.lands.has organized more than 90 nonprofit organizations tobegin planning statewide. science-based wetland resto-ration M. Hansc<im, Save California Wetlands, C<i<irdi-nator for Sot<them California, personal communication!

The goal of restoration is to pr<ivide self-sustainingecosystems that closely resemble natural systems in biith

PACIFIC COAST ESTUARIES AND WETLANDS 9

na River National Estuarine Researchrvetvvater Marsh National Wildlife Refuge,

a Vista Wildlife Reserve, South San Diegoe Reserveon Bay Marsh Kendall-Frost Reserve!,osa Slough, San Diego River MarshPenasquitos LagoonDieguito LagoonElijo Lagoon Reserve and Regional Parkuitos LagoonHedionda Lagoon

a Vista LagoonLuis Rey River Marsha Margarita River Estuarylores Marsh

Mateo Marshort Backbay State Ecological Reserve

a Ana River MarshChica Ecological Reserve

Beach National Wildlife Refugena Wetlandsu LagoonLagoon

21. Ormond Beach Wetlands22. Santa Clara River Estuary and McGrath State

Beach23. Ventura River Estuary24 Carpinterla Salt Marsh Reserve25. Arroyo Burro Estuary26. Goleta Slough State Ecological Reserve27, Deveraux Slough28. Gaviota Creek Estuary29 Santa Anita Estuary

Ffgtrre t.5 Location ot malar Southern California coastal wetlands and rivers

Table 1.3. Habitat Areas and Changes at Tijuana Estuary, San Diego Bay, and Mission Bay,Ban Diego County, California

AreaChange

+507

O/

ChangeRecent1984-87

507

Historic1856

0Salt pondsIntertidalsalt marshrnudflats, sandflats

Total intertidal

255407

662

1,9262,503

4,429 85.1-3,767

Subtidal lrel. to MLLW!0 to -1.8 rn �'!-1.8 to - 5.5 rn I 1 8'!below -5.5 rn

Total Subtidal

9732.3181,7275,018

3,105984925

5,014 +<0. t+4

htote: MLLW = Mean lower low water Areas are ha. Data from Macdonald 1990.

1,4 THE GQAE OF THIS BOOK

St<UC ur<'. 'nlcl funCIIOn. H<iwcvel, e<perienCC SI1<iw'i tlllitres lira iiiri Silei dO n<it tuiiC1iiin ai well;is iiaturui Wel-lanili see chap eri 2 an<13 and iecti<ni s. I I. Case studiesffon'I Bri ish C<ilumhla o Ihe Mexican b<!rder inclicate awide range of probieiiii Ichaptcr 2I, and detailed invest>-gati<irii in San Diego Bay ILangis e al. 1991, Zedier199.T. C<ihson ei ai. 1994! sh<!v th it nii igation si ei canbe tunC11Onally lmpaire<t fnr m<ire thai< a <teeade afterc<instruc1ion. Fur herrnore, mcaiurei tii correct the ihort-C<>mings <it mitigatiOn pnijCCli C;in be leilgthy and COstly section 5. I I.

RCiliiring he funeliiini aiid Valuev Ol C<iaii;i! Wet-I;indi requlrCi appr<ipria c p! arming� lmpr<iVed inipICmen-I<i <<in, L'XIL'nslv<.' an<i inlenslve <iiaesillli.'n , iul<j Icillg- <'rln;i<hlptivc niartagenicnl. I is irnp<irlant «i consider whalhahiiats werc hlstiiric;illy prescn as well as wha valuciare still plL seri a si CS iCI CC e<l t iir C<nli ruC lun or rei-liira i<iii. Further CftOr i are needed to determine Whatilllpairi the funC iiinirig of res orcd ec<isyxtemi OVer heah<in <in<! Iiing ierliil, and neW melh<nls Will he required <i;<CCciler;<te the <ievel<ipiiieiit Of Crl iCal CC<iiyitem prO-cciics

Res <iratiiiii cff«rti will alway» be based on inc<imple ehn<iwicdge <if' the physical and biological conditioni andproceiiei ot'emergcn narsheS. We are on a steep learn-ing curie, both because restoration ii a reiativeiy newnlanagenien 'I<!ol and because so fe w attempts have beencarefully studied. The primary goal of ecological s udiesof restorati<in cfforts i.i understanding how ecosystemfunctioni develop an<i hov hcy compare with naturallyfunc1ioning iys ems. Know ledge of natural wetlandsh<.lpi in set1 ng performance standards, and knowledge<if created wetlands helps iii determini<tg limiting fac1orsand in developing solunons to probterns. With under

standing should conic grea cr ability t<i rcit<irc or createna urally fiincl<oning wetlands and greater predic abil-ity about when an<i h<iv much n iturai functioning willdevelop.

in this b<aik, ive review Several effo ts tov ard we -land rei Orat On Chapter 2!, t<icusing on the WOrk OfPERL. Restoration of tidal flushing, chanriel habitat, andaii endangered plant population are considered in de ail.Although our v ork hai been confined to Southern Cali-fornia. iiur revlev Of prOjeC S alOng the PaCifiC CnaS shows hat problems arc widespread: each caie studypr<ividcs cine <ir two important lessons for future restora-tion attcrnp s. On the basis of these and our own experi-ences, we indica c a number of prob! ems that constrainres oration chap1cr 3!, inclu<jing the roles ofexcess runofi, urhaniza ion, and invasi<mi <it' exoticplants. Next, we recommend ways O improve planningby taking a regional approach 'chaptcr 4! and to acceler-ate the deveiopnient of ecosystems chapter 5!. We thenOffer SuggesliOns fcr irnpr<iving the aSSessmen Of reStO-ration sites chapter 6!, inctuding recent applica1ions ofhigh-reiolut ion remote icnsing. We conclude with rec-<imniendatlons for managing reit<iration siteS adap ivelyIchapter 7h

This is nor a c<imprehensive guide to restoration otc<iaitalwetlands. 1 is ail update <if f'indings and scien-1iflc perspectives hal have developed al<ing with ourSouthern California research prograin. We summariaebriefly the information that has been published in, oriubml tcd o, the peer-reviewed literature. We prOvidemore details for w<irk that has not been pubhshed else-where. The information here builds on earlier restora-tion-oriented guidebooks Zedler 1984, PFRL 1990'h butwe s iii consider our research far from complete. In fu-ture years, we expect o understand bet er the problemsof wetland lestorati<in and O have mOre corrective mea-sures. Most of a! I, we hope to report examples of restoredv etl ands that are functionatiy equivalent to natural ones.

CHAPTER 2

Restoration Effortson the Pacific Coast

2.1 INTRODUCTION

Wetland restoration is undertaken by rcs<iurce agencies o improve stocks ot selected species or <> enhancebiodiversi y in general. Often res ora i<>n is accomplishedthrough niitigation programs that give credit for improv-ing hahital quali y or quan ity in exchange for allowingdamages to other wetlands. This chap er is a review ofseveral Pacific Coast restoration efforts. It is n<il exhaus-tive, hut the examples illus rate a br<vad range of issuesand prob!cms in the restoration of coastal wc lands, lorexample, he va! ue of tidal flow. the creation of fish habi-iai. and he challenge of sustaining populations ol an-nual plants in he salt marsh.

PERL has been directly involved in the pro!ects dis-cussed in sections 2.2 � 2.4. and bo h the iliflicultics of

and promising appr<iachcs for enhancing biodiversity inSouthern California coastal weltands are discussed. In

section 2.2, we compare four wetlands and relatebiodivcrsity tu tidal hydrology. This comparison of siteswith differen degrees of' tidal ac ion provides a scien-litic basis for the common restoration goal of increasingtidal influence. In sec iiin 2.3. wc. evalua e clt'orts o cre-ate tidal channel habitat for fish and benthic invertebrates,which are needed as forage by endangered birds. Manyproposals have been developed to create fish habitat inSou hem Catifornia as mitigation for tilling <if'nearshorewaters to expand porl facilities and for entrainment off'ish larvae by cooling wa er inlakes of pov er plants. Insection 2.4, we describe problems encoun ered in rees-tablishing an endangered plan . A erupts to restorecordgrass vegetation for nesting by light-f<ioled clapperrails have encountered difficulties; ef'forts to improvesuch projec s are discus~ed later, in section S. I. Finally,

RESTORATION EFFORTS ON THE PACIFIC COAST

in section .S, several brief case studies from Cahfornia1o British 6 <ilumbia are presented. Each indicates a prob-lem or concern that swerves as a lesson f<ir lu ure restora-tion or habi at-const uction projec s.

2.2 MAINTAINING TIOAI FLOWS INSOUTHERN CALIFORNIA LAGOONS

.loliii Bol<rn<J rnid Juv Z< <ll<v

Urban development has reduced the size of SouthernCalifornia wetlands, and roadways have dissected manyof them into two or three basins connected only by nar-row channels. Several bodies of water tha were onceopen o the ocean are now often closed to tidal flow Cali-fornia Stale Coastal Conservancy l9I!9!. In this condi-tion. they are usually called lagoons and often are con-sidered "degraded." Current restoration plans call forrestoring and maintaining full tidal flushing at SanDieguito Lagoon MEC !99 i!. Batiqui os Lagoon Cityof Cartshad and U.S. Army Corps of Engineers 1990!,and the southern arm of Tijuana Estuary Entrix et al.1991!. The San Dieguito and Ra1iqui os lagoon projectshave been designed 1o mitigate tosses t<i nearshore fishpopulations; funding has not been determined for heTijuana Estuary Tidal Restoration Plan, Additional planshave been developed to improve tidal ftows to BallonaWetland just north of Los Angeles Intema iona! Airport.Most of this wetland was excava ed o create Marina delRey. The site is virtually non1idal; it is c<mnecl.ed to theocean by culverts tha have one-w ay flap gates to a!lowfreshwater outflow but little tidal inflow Roland andZedler 1991!.

Although restoration of tidat flows is considered thebest way to enhance many of these! agoons, the cause-effcct relationships between tidal inflow and biodiversityhave not been fully evaluated, Here we use data fromfour coastal wetlands to compare he biota of sites wilhdifferent tidal-flushing regimes Fig. 1,5. sites IS. 6, 4,and I!. These patterns of occurrence in relation to tidalflow suggest cause-effect hypotheses, which can be tesledby studying lagoons before and after restoration of tidalflows. Such studies are needed to predict more precisely

12 TIDAL WETI AND AE<>TORATIQN

lhc henef>ts <>f inc>>eds«} idal ll<>v and. !o«»»>ga i<'>1projcc s, tah mitigi>lion crcdi s dss<ici ««d wi hdifferent degrees of tidal enhance inenl.

2.2.1 Differences in Tidal FlushingThe four s udy sites are subdivided into three hydn>-!Og>C ypex «CCording o he niuure of lhe ocedn i>>letTheSe C<uiditi<inx >apres<'iit diff'eren pOinhs dh>ng a speC� rum that ChdraeleriZCS be<hex of wd'Ier JIOng the Suuth-crn Califori»u coast sec l"erren ctal. ! 99S for a morede ailed hydrologic classification scheme!:

1 . Fully tidal. inlet nearly alw iys <>pen c g.. Ti juanaEstuary!

2. lnle frequen ly closed le.g., San f!ieguito1.«goo� i >id Los Pciidsq<ii i>s Lagoon!

3. !nlel with a berm, weir, or i>de gale allowingwat<'.1 o !low <>ut bu excluding iidal inflow e.g.,8«l luna WC !iind I

The n<>rthen> arm <>f"Tijuana Es uary is a tully Iidalsys em; this pari ol' th» estuary has recei ved a>ore s udy Nordhy and Zedlcr 1<!<! !; 'A.dlcr, Nor dby. and Griswold! 9<�; Zcd!cr, Nordby,;ind Kus 1992! than the southern.less idally inllucnced am> Entrix el a!, ! 99! !. Reducedtidal inliuence in the southern arm is d function of sedi-mentation from thc v, atershed and dune washover e ventreBo h the area and hc length» of'channels have been re-duced, and much i>f lhe sal marsh h«s dccumula edenough sedin1cnt lo raise he marsh above tidal influ-en c<'..

l.xarnples ol' f'requcn ly closed lagoons are I.osPeniix4<l>tos l,dg<>O� Cuvi>1 I !I�. Greenwald and13riu<>n !<!!�; Ni>rdby and Covin !9HI ; Nordhy ! <!f 9,!<!<! Ia; Ni>rdhy und Zedlcr !99!'I «nd Bo!and ! 9<,!W2a, l<!9!a, !V<�b! and San Elilo Lagoon INordbyf <!<! Ih; Ho!and 1 <!92b, 199lc, ! 994!. Inle » «re typicallyopen during win cr af'ter rainfall tha1 is sufficieilt for ui>oft'lo break hroug,h the sand berm at the inlet. Hence.!agouns are susCCptihle td by pcrsalinily in summer. Bo hlhc iii>ing id the dura i<in ol' chisures are highly < ar>-able Webb ! 98<! I.

Ha!h>na Wetland is an example of a wetland where ides «re excluded by a idc gate PERL ! 98<!. Bo!andand Zcdlcr ! 991, PERL unpublished da a!. Other wet-land~ in the rcgi<>n that lack tidal inHuence have inletswi h a weir IBuena Vista I.dgoon! or persis ent buildupof cobbles and sand, which form a high berm Bati<!uitosLagoon!,

2.2.2 Chart tel Charscferisf!cs attdAquatic OrganisrrtsThc salinity of channel waler influences the abundanceof' species within the channels. Most estuarine fish dndinvertebrates are species that thrive under narine COn-ditions, and their abundailces are thought lo decline un-der extended periods with water salinity less than �

ppl, ha >s, less ha>i <ine- bird scawa cr Ic.g., Calif>>rniahalibul Purufi< irr!r>s <xiii/i>i.nir u<", Bacxkowsk> !992!.When '1'ijuand Es1iiiiry is fully iddl. hC avCrage salinilyof' Ihe surface v alcr in the ida! channel I'luctua cs li tie,and during dry wc« her. it u<erages 32 ppt Fig. 2.1!. At he other si cs, s;i!inities are likely t<> be more slressful toorg«n>vms in thc channel. At hc lrequeiitly closed la-goons. c<>ndilioris «re less prcdic able: San L'lijo Lagoonis gener<illy brackish, wtlere«s Los Peiliusqui1os Li<gooncan be brackish <ir hypersaline, A San Flijo Lagoon,f'rcxhv alcr inflow's have ex<>ceded evapora ion, v hereasat Los Pen@aqui os Lagoon, thc reverse hds been ue. AlBa! !Ona WCtlai>d, an ups re«m deWalcring pmjeCt re! eaSedfresh water into thc crcck and reduced channel saliniliesduring 3 months in late summer. Thus, the condii.ion ofIhe <lucan inlc has a malor influence on water salinity,bul the ef 'ec depend» on the amou»l of s reamf low.

Piiorly flushed channels are suitable place» for rapidgrowth of' rnacroulgae and the vascular plant R q>piarriarirrn>ri. Plant hiO>nasa inCreaSes during suinn1er, and hen during autumn the plants begin 1<> die. The decom-posers of these plants bccoine extre nely abundant andrnetaholi cally deplete the amount of dissolved oxygen in he water cotunln, par icularly at night.

Oxygeii Concentrations affect the abundances Of Chan-nel organixmS. LOW COnCentra1iOnS Cd>1 cause eX enSiVemortality of fish and inverlehra es. In Oc obcr ! <!g7, �species and an estimated 6,200 f'ish were killed at LosPenasquit<is Lagoon during one of' these events. Thecounts done af'ler that kill illustra e no only the magni- udc <if the problem but also the na urc of the channelihio a: about 5,000 topsmel t, A rheri r>r>p» apir>i 1; C I S dia-mond turbot, Hypsr>pse ra gut ala a; 500 dcepbody an-chovy, Ar>i/rr>u < rrmpressa; ! 34 California halibu ,Pur'<rli<'l>lh>'» <ulifi>rni<us, 11 Pacific slaghorn sculpin.Lep r><'r>r us arr>>urus: 4 barred sand bass, Para a!>raxnef>uli fere 2 CalifOrnia COrbina, Mer>rrri >ThWS ur> Jula ux;2 shiner surf'perch, Cvrr>arr> gusrer aggregu a; 2 opaleye,fiirellu nr gr icaris; and 1 ycllowfin goby, A<'u»r!>r>gr>hi>isf!aiir>rr>nrrs C. Nordby, unpublished data!. ln fully tidalsystems, oxygen concentrations are consis en ly abovelethal ! cve! s. >x herc«a in frequently closed estuaries, con-centrations often decrease to less than 0 mgJL, particu-lar!y during late summer and fall Fig, 2.2!.

The channel sediments of frequently closed estuar-ies are usual!y very hne, highly organic, and anaerobic,whereas the sedimen s a f'ully tidal estuaries have moresand and are more readily aerated at !<>w tide. The oxy-gen content of lhc sediment inf!uences he organisins! iv-ing in he. sediments, and many species arc intolerant offrequent anoxia. The benthic invertebrate comrnuni y atTijuana Estuary had more species, particularly morc large.long-lived species fe.g., bivalve no!!uses. C'alIia>tassa< a! rfr>rr>r e»sr s!, than the other estuaries Tab!e 2.1!, Small,short-lived polychaete worms were more abundant at theother three sites,

Fish v'ere more abundant at Tijuana Estuary than a


Numbers atBW LPL SELTax on TJE

Sipunculid wormsThemis te sp.

Echi no id ec hinoderrnsDendraster excentricus

17

6

93Nemert can worms

Polychaete worms

Cap i tell idaeSpionidaeBoccardia s pp.

Polydora comutaPolydora lignlPolydora s p p.Spiophanes missionensis

OpheliidaeEuzonus mvc rona ta

Other tax a combined

29814 39969

41 0

0 0 00

010

2,631 �!0

183 �!1892

210 �!0

68 �!12414363 �!

117

0'l1 �!

046 �!

162161

0437

Bivalve rroliu scsTagelus caltfornianusProtothaca starnineaMacoma nasvtaL aevi cardi um subs tria turnSpisula sp.

Other species combined

Other molluscsCari thi dea calif orni caAssi mineaLacunaCyttchnefta

Decapod c ru st ac cansCallianassa californiensis

797554221300

227

40468

1717

101001 �!

55

00

03711

234

Other crustaceansAmphipodsI sopods

insectsFly larvae

PhoronidaPhoronis sp.

Total number of tax a

570

2, 1041

145

114

212212

3,946238

1, 253

Total number of individuals 1,440

377

5,003

752Mean density individuals/rn !

Total sampling area rn !

Total number of stations seasons x sites!

Dates

1,573

5. 250. 19 3 82 3.18

11 x34x6 8x3 5x4

1989-1990 1986-1988 1987-1988 1991-1993

Atote: Numbers in parentheses are numbers of species, BW = Ballona Wetland, TJiE = Tijuana Estuary,LPL = Los Penasquilos Lagoon, SiEL = San Elijo Lagoon.

N~mb~rs of Individuals of Benthic Macroinvertebrates Collected at FourS out he rn Ca l if or nia Coa stet Wet Ia nds

r DAL wETLAND RESTORATION

5040

4030

<l.Cu

~20

E<atp 10

30

20

10

0Ap May Jun Jul Aug Sep Oct Nov

1989

Feb Nlar Ap May Jun Jul Aug Sep Oci Nov Dec1986

4050

40

cucl

30

20«iCO

30

20

1010

0 0Feb Mar May Jun Jul Aug Sep Oct Nov Dec Jarf M a r May J u 1 Strp Nov

1989 1992Figure 2,1 Bafinities ot channel waters ai four Southern California estuanes Surlace salinities only are given for Baf lone Wetland and TiluanaEstuary Boih surface and bottom salinities and timing ol mouth closure are shown for Los peirasquiros Lagoon and Ban Elilo Lagoon Error barsare s t SD, Number ot sample sites: Ballona Wetland. six; Tifuana Estuary, four. Los Penasquitos Lagoon, three; Ban Ealo Lagoon, tiveQ mouth closure, Q bottom salinity. ~ surface salinity.

the other sites Tahlc 2.2!. Bo h he number of speciesand ihe density of individuals were greatest at TijuanaEstuary. The c<rmmunity compositions a Tijuana Estu-:iry, Los Penasqui os Lagifon, and San Elijo Lagoon weresinrilar. arrow goby, topsnreii, California killifish,longjav; mudsucker, and s aghorn sculpin were the mostahundant species. At Ballona Wetland the less salt-tolcr-aiii mosquito 'ish was ihe most abundant spei.ies. Notelha he lish and invenebrate data eels have different de-grees of sampling in ensity and span different years. Theirusel'ulncss in making <omparisons is limited.!

2.2.3 Relationship of Salt Marsh Vegetation toTidal InfluenceThe composition ol'plan communities differ~ among thelagoons compared here Table 2.3!, The salt marsh a Tiluana Estuary is riches in species. Three species foundhere are no found at Ballona We land, Los PeaasquitosLagoon, and San Elij<r Lagoon: Brrri s mv ri i ma. Li mrrni<rrn<'<»ffrrr rtir f<m. and 51rurrirtv jrrIirrsv, Ar Ballona Wetlandalrd Los Penasquitos Lagoon the salt marshes are spe-cies-poor, and they are essentially mono ypes ofSrrIi<'rrrniu iireini< v. San Elijo Lagoon is similar to Los"eflasquiros Lagoon. except the relative abundance of

.SuIi < rrrrrfu virvi nicu is reduced. and brackish mar sh spe-cies have encroached on the salt marsh. Sari Elijo La-goon is usually flooded, and areas tha are rnudflat v auldlikely supp<rrt more extensive stands of Svlir <rrnivvirgi ni< v if the inundation period werc reduced. In fact,Srrlir"rrrrrra iir qinir v invaded ihe mudflats when the<rcean inlet was kept open for several months in 1994 l,j.Boland, personal observation!,

ln general. Southern California salt niarshcs wi h a!ong history ot good idal llushing. tend o have morenative sal marish plant species than marshes v ith inletsthar close f PERL 1990!. The elimination of many halo-phytic plant populations appears to be due to extremehypersalinity and drought thar can accompany inlet clo-sure. We found hcavy mortality of SvIi< nrnia hil;< Irrvik.S«uedu esverrru, and .Spurrinv frrlirrsu in 1984, whenTijuana Estuary was closed to tidal flushing and marshsoils deve!oped salinities <rf l04 ppt by laic summer Zedler ct al. 1992!. Similar declines occurred in a dry,nontidal diked! portion of Estero de Punta Banda, B ajaCaliforni, that same year Ibarra-Obando and Poumian-Tapia 1991!. Los Penasquitos Lagoon had a luxuriantpopulation of S. fnli<rsv in the late 1930s Purer 1942!.However, the lagoon was closed ro tidal flushing for g

1 5

Oi

E e1 0Q!O!!C

0 o 5Q!

0

iC! 0 Feb A p r J un Aug Oct Dec1986

1 0

E Q!w 5

0 co! 0 c<rcri

0 Feb Mar May J ul Sep Ocl Nov Dec1989

I 5

0!

E ot 0Q>

0 0CI 0 Jan Mar May Jul Sep Nov Dec

1992

Figure 2.2 Dissolved oxygen concent<ation ol channel waters atthree Southern California estuaries. Surface oxygen ooncentra-tions only are given for Tijuana Estuary. Both surface and bottomoxygen concentrations and hming of mouth closure are shown forLos PenasquitOS and San Elijo lagOOnS. Error bare are = 1 SD.Number ot Sample sitee: Tiiuana Estuary, lcur; Los Per!acquiresLagoon, four; San Elijo Lagoon, five. g mouth closure, Obottom oxygen concentration, ~ surface oxygen concentra-tion.

years December 1958 I<i I'�6!, and by 1 96k .'!p<rrfi!raf<i/iuiu had disappeared from lhc area comple cly Rradshaw 196g!.

Soil salinities in thc salt marshcs have been sampledin summer in these coastal marsheia they are generallyhigh al 1 ijuarla Estuary auld low, at the other s! tes Fig2.3!. Maxinrtt heights iif !crfi«!i rrf<r I'<girt«''cr arc sir '!rtal Tijuana Es uary and taller at Ihe other sites Fig. 2.3!.There is a strong pa tem of short plan canOples occur-ring where soils are more saline. tliiv ever, n !n-sallmarsh vegeta ion invades where soil salinities remain! ow for too long see section 3.4.4!.

2.2.4 Resident Salt Marsh BirdsTwo endangered bird species hreed irt hc sall rnarshes;of these, Be ding's Savanrtah sparrow. P<rcsc'rc'frit<a.!urtd!!i<Ac!t!is br dirt<i, iS the tnnre COmmOn. Eightpairs ol this species bred at Ballona Wetland, 156 atLos Pefras juitos Lagoon Roland and Elrod 1993!. 30at San Elijo Lagoon R, Pat on. personaI cornmunica- ton!. and 144 in the northern arm of Tijuana Estuary.These data suggest that sparrows do svell in impoundedand fully tidal wellands but poorly in areas where tidesare excluded.

Thc light-fo<ited clapper rail nests almost exclu-sively in 1'ully tidal esluarierc The rail w«s abundant inTijuana Es uary gg breeding pairs in 1993!, not Foundin Los Penes tuitos Lagoon turd Balliina Wetland. andrare in San Flijo Lagioon fapproximtt ejy 5 breedingpairs!. Los Pefras luitos Lagoon and San Elijo Lagoononce supported large papula i<ms i!t' rails, but persis- ent flooding contributed to making these rnarshes un-suitable for nesting Zembej and Massey 1 13!.

2.2.5 Summary of Patterns Associated withTidal InfluenceThese con!parison s ol' three tidal regimes sug gee strongcorrelations between hydrology and blodlverslty, withmore species present in fully idal sites Table '4..!. Sallmarsh plants, benthic invertebrates. and fish appearedto be more species-rich in the fully tidal Tijuana Estu-ary than elsewhere. This i» probably due o lhe narrowerrange of environmental conditions in fully tidal systenrs.Estuaries with open inlets are less likely to experienceenvironmental extremes. The three mOS important ex-tremes appear to be �! events that produce low oxygenconcentration~, which lead o deaths of channel organ-isms, particularly fish and invertebrates: �! long-termt1onding of the sah marsh by low-salinity waler thaimakes salt marshes unsuitable for breeding birds andmay eliminate salt marsh plants thar are less olerant cifanoxic soils; and �! drought and hypersalinity attermouth closure, which eliminate lish, invertebrates, andthe less salt-tOlerant halophytes e.g., Sp<rrfincr fi!iinscrl

If rhe correlation between tida! flushing andbiOdiverSity is a causal relationship, then increasing tidal

TIDAL WETLAND RESTORATION16

Table 2.2, Total Number of Fishes Collected at the Four Southern California Coastal Wetlands

Numbers at

TJE LPLew- SELCommon Nane

5890

5192

4x61990 � 1 991

135,067

31,9858x3

1987-1988

122,196

2,0005x4

1991 � 1 9%

flows from frequently nontidal lo fully tidal should al-low more species to use lagoons that are kept open tothe Eicean. provided that periiid» ol anoxia and extremes<Ef salinity «re either prevented or kept brief'.

In 1992, channels did nor become hypersaline duringsummer and did not remain low for long periods duringrain events. SeCond, the di skill ved oxygen concentrationsmeasured during 1992 were a!so much higher. The aver-age concentrations on the bottom of the channel neverfell beiow 2.S mg/L during 1992 F>g. 2,4!, whereas thisoccurred three limes in 1986. Finally, more benthic in-vertebrate species and individuals were present in Sep-tember I 993 than in September t 989 Table 2, S!.

However, neither the vascular plant communities northe general structure of the fish assemblage of I,osPefiaSquitas Lagoon changed greatly afler iinprOvemen in tidal flow Tables 2.6 and 2.7!. These communitiesmay require more time to change, or the structure of thelagoon may play a rille. Species cannot reinvade a coastalwetland without opportunities for establishment and ref-uges for them to persist. A f'ally vegetated salt marsh

2.2.6 Effects of Improving Tidal Flushing atLos Pehasqultos LagoonSeveral dredging Operations at the OCean inlet between1990 and ! 994 increased the duration of tidal flushingto Los Penasquitos Lagoon from 23'A of the time in l986to 959o in l992. A comparison of data collec ed before

d after tidal flows were improved helps test the link-age between hydriililgy and biology.

With improved tidal flow, three aspects of LosPenasquitos Lagoon became more similar to TijuanaFstuary. First, salinities of the channci water s during l992I Fig. 2.4! were less variable than those in 1986 Fig. 2.1!.

TENon

Ac~us IlavimanusAnchoa compressaArteefus sp.Alhennops affinisCleveland'a ios

Cypnnus caipioEngrauii S markhxFunobfus par vipinnisGem busia affi nisGigichfhys mi rabrksGiraffe nigricansHypsobfenni us genfi i sHypeabfenniuk gilbevdH ypsobfenniusf enkinsiHypsqoselfa guffuiarafly@ac gi/berliLftpfcagatruk lepr'rtikLepfocofftisarmalusMuglf cephaiusParalatrair clafhralusParalichfhys cahfornicusPfueroni chlhys ri lferiQui efula y- caudaRhinobsfos procticfusSer Jphue pcfllukSyngnafftus lepforhynchus

Total number of speciesT alai number of individuals

Mean density hndivi duels/m2!Total sampling effort aumulab ve area in m !hfa. Of SfallanS SeaSailS x Silek!Dates

Yel lowfin gaby

D~ anchovySaul pinTopsrn alt

Arrow gobyCarpNorthern anchovyC alifar ni a k illifi s hM aequi tofishLang aw muCk uckerOpal eyeBay bi ennyRockpool bi ennyMussel bi ennyDiamond turbot

C heck spot gobyBay gabyStaghor n scul pinStriped mulletKelp bassCalifornia halibutSpatted turbotShadow gabyShovelnose guitarfishClueenfiah

Bay ppehsh

0 0 077

10 0

0 8779

16 0 0 0 00 0 0 0 00 0 0 0 00 0

0112

15.43760,097

00

2,3670

27582411

83500

1,4315

12283

432

14

21

80,16517

4,79512x4

1986 � 1 988

0670

1.875816

00

107937877

0000

14229

34630

1200002

1

6 01,744

01333430

2352

0 0 0 00 0 0 3 10 4 0 3 00 0

Table 2.3, Dominant Salt Marsh Vascular Plants at Four SouthernCalifornia Coastal Wetlands

Percent atTJE LPL SELTaxon BW

6

288

1,475

Total number of species

Total number of quadrats

Total length of transects m!

7 8

259 107

10

277

1,435 1,330 660

/tfote: BW = Ballona Wetland, TJ E = TijuanaLagoon, SEL = San Elljo L.agoon.

= Los PenasquitosEstuary, LPL

75

50o.a

25ni

0

�5!TJEBW LPLSEL

TJEBW LPL

Hatrs marrhma

Cressa truxillensis

Orstichks spicataFrank enia grandi foi aJaumea carnosa

Lasthenia glabrataLrmoni um cab'forntcum

Monanthachloe littoralis

Salicornia subterminaks

Salicornia virgmrcaSpartina foliosa

E75

oiiTi

a o

50frr

n

rrr

825

iriSi

0

0

6 7

0 00 183 0

11

4

4 7

0 812

31

21

0 2 2l5 1

0 0 180 0

RESTORATION EFFORTS ON THE PAClFIC COAST

0 910

10

15 10

8

46 0

Figure 2.3 Average soil salinities and Satrcornia virginicacanopy heights in the salt marshes at four SouthernCalifornia estuanes. Error bars for soil salinnies are + 1SD. Number ot sample sites: BW = 26. T JE = 18, SEL =19, LPL = 29. Error bars for canopy heights are. 1 SE-Number of sample sites: BW = 27, SEL = st, LPL = 23.BW = Bellona Wetland, TJE = Tijuana Estuary, SEI = S»Etifo Lagoon. LPL Los Penasquitos Lagoon

tS TIDAL WETLAND RESTORATION

Table <t,4 physical, Chemical, and Biological Characteristics of Four Estuaries inSouthern California

S ite

Loa PenaaquitOS andSan Elijo Lagoons Frequently Nontidaf!

Bellona Wetland Tides Excludedj

Tijuana Estuary Fully Tidal!Characteristic

GeneralNature of mouthFate of freshwater

inflows during;Winter/springSummer/tall

Outflows only Always open Seasonally open

Out mouthOut mouth

Out mouthOut mouth

Out mouth

impoundedChannels

Salini tiesOxygen concentrationDominant plantsSediment anaerobic

depthNo. of invertebrate

species, individualsNo. of fish species,

individuals

VariableNo dataEnterornc!rpha

MarineHigh Phytoplankton!

VariableOften lowPhytopiankton, Ruppia

At surface Oeep At surface

Few Many Few

Few Many Few

Salt MarshesSoil salini tiesNo. of plant speciesSa//cornia max imal

HighHigh

LowLow

ModerateLow

height Tall Short TallBreeding birds BSS! CLT, CR, BSS CLTI, CR!, BSS

Note: Organisms listed in parentheses are not abundant. BSS = Be ding's Savannah sparrow, CLTCalifornia least tern, CR = clapper rail.

ol'fera few open spaces f' or seed! ing establishnten , espe-ciallv ~here the <>vcrslory canopy is tall arid dense.

We bink that hsh assemblages are affected by idalflushiiig, but that Los Penasquitos Lagoon has too muchlreshwaier influence even when it is kep upen to ttdalflows. The lish assai!!binge at Los Penasqui os Lagoonis;ulversely >flee cd by winter population crashes hat'ire r! >t eh <I"1clerlstic of Tlluaria I.stui<ry ct. I 1g. 7 inN<irdihy arid /edfer l gal l. The winrer crashes i»ay pre- is>1 tbe tish c >ir!niui!ity tr»!1! developing fully. At I.<isPeilasqui os Lag<ion, the i!un!ber and sizes of refugesavailable t» f'ish daring rain-induced fl<iods rnav be ii!-adequate. Refuges are needed o prevent h>w-salinityfl u!d waters from killing fish rind to keep strong cur-rents from washing t'ish out io sea. In Los PenasquitosLagoon, bo h main channels carry flood flows to the iccan, and the sahnity ot virtually the enrire lagoon isreduced. In contrast, the northern arm of Tijuana Estu-ary acts as a refuge, at least during lesser floods. I'loodwater/ rush down the river and»u the mouth. The smallerarea of tidal intluence and the simpler channel system ofLos Pef>asquitos Lagoon may prec/ude the devcl<ipmentor main enance of fish assemblages as rich as those thai

occur at Tijuana Estuary, even if tidal flows were fullyrestored.

2.2.7 Conclusion

Comparison of the four coastal wetlands that differ indegree of tidal influence suggests that hydrology andbiology are strongly related and that fully tidal systemsare m<ire diverse biologically and less variable environ-rnentally than trequently closed lagoons,

The changes that occurred a Los Penasquitos La-g<'!on show that increased ridal flow made i mor« likeTijuuna Es uary aiul thar rapid iniprovemenis occurredin sahnily, dissolved oxygen conccnrrm-p<isi ion ot tish and salt marsh plants suggests that thesecommunities need more time to change or that hc struc-tul <. »f the iagoori restricts he number of refuges neededby fish or the <ipportur>ities for establishn!ent of vascu-lar plan s.

I-'ull idal tlushirtg is a desirable restoration goal forfom!eriy tidal coastal wetlands in Sou bern California.With full tidal flushing, Balf»»a Wetland, LosPehasquitos I agoon, and San Elijo Lagoon could

Table 2 > A»nda«es o< Etenthtc Macroinvertebrates Cotiected at I os pehasquitosLagoon During September 1 98g 1 g93

Number1991 1992 1993Taxon 1989

1,53465528230

31020

3650

28010

'l3

1379

f9

CrustaceansOrches tea traski anaHemi graps us oregonensisUnknown amphipod

3000

552

0

59112

359

0

InsectsFly larvaeTrichocorixia reticulata

015

13700

22441

11664

6637

181,157

192,903

The mouth ot the lagoon was closed in 1989htote' No data were collected during September 1990and open during 1991, 1992, and 1993.

Polychaete wormsCapi tell tdaeSptontdae

Polydora nuchalisPoly dora sp

Cirratul tdaeOphe! kdae

Armandla brevisG ly ceridae

Hemipodus borealis

Bivalve molluscsTagelus cali fomi anusProtothaca stamineaMusculista senhousiaTettina s p.Laevicardiums p.Mac orna sp.

Other molluscsCykchnetta culcitellaCerithfdea cali fornicaNavanax sp.Bulla gould'kanaAlderia modestaAssimenia cali fornica

MtscellaneousPhoronidaNemerteaAsteroidea

Total number of taxaTotal number ot individuals

18 0 0 0 0 040 0 0 0 047

25 24 10 0

385

1850

20929

2237

9

18550

10 0 0

20 TIDAL WETLAND AE STOA AT ION

0>' lo

X

o 5ICI

0Jaf! M a r May J U I Sel3 Nov

50

%40

Eg 30

20

10

0

Jan Mar May Jul SeI3 Nov Dec

1992

Ffgure 2A Saiinily and dissolved oxygen cr>ncenfra<ions r>f surface and bottom channel water and liming of mouth closure al LosPef>asqu>fas Lagoon dunng 992 Err<>r bars are < f SD n = 3 sites!. Q mouth closure, ~ surface, Q bottom

8rfr< C A!rderr rind Ji>V ZeJler

pniv>dc ininc hahi at for native vascular plants, and sup-por inure endangered hirds tha reside in the salt marshand nii>rc native marine invertehrateS and fiahea. HOW-

ca el, son'lc si cs nluy support othe> valued species andh;ivc al crnativc values that would bc lost under I'ull lidallti>W, Ir<>1 e><afnpte, marly Wa ef'fuwl ilse impourided Wa- d re aS sir>l>iivel s dul'lrlg nligralfu�. and s011>e Wadersprefer ti> nest a r>onlidal water hudieS tef. Se<.tiOn 5..'<!.Individual estuaries should he assessed carefully hetorerestora i<n»>f full idul flow is advocated, and a stra -egy sh<>uld bc developed to coordinate res oration ob-jectives within the Southern California region section

2.3 CREATING FORAGING HABITAT FOR THECALIFORNIA LEAST TERN AND LIGHT-FOOTED CLAPPER RAIL

As part of a mitigation project under the EndangeredSpecies Act, the California Departrnen of Transporta-tion Caltrans! was required to create foraging habitatfor two endangered species of birds. The California leasttern .'>ter>ra albifrorf a hrr>«ni! requires dccpwater habi-tat for feeding on small fishes; hc light-footed clapperrail requires tidal creeks for foraging on crabs and othermac roin vertebrates.

Channels were construe ed at the Connector Marshwithin the Sweetwater Marsh National Wildlil'e Refuge

in 1984. The constructed channels must provide supportfor at least 75'7< of the nalivc species and 75% of theindividuals of native species found in the reference chan-nels U.S. Fish and Wi!dli fe Service 1988!. In 1989, PERLbega~ comparisons of the fish and invertebra e assem-blages of construe,ted and natural channels. A samplingpn>gram to determine water quality was developed to help

Table 2.6. Abundances of Fishes Collected at Los Peftasquftos LagoonDuring June 1989-1993

Nurnbe r

Common Name 1989 1991 1992 1993Species

Acanthogobius fiavirnanus

AnchOa CarrlpreSSa

Atherinops aftinis

Ctevelandia ios

Yellowfin goby

Deepbody anchovy

Tops melt

Arrow goby

Northern anchovy

California k illif is h

4.822

88

0

0

Engraulis mordax

Fundulus parvipinnis

Gambus<a af finis Mosquitofish

Longlaw rnuds ucker

Opaleye

Diamond turbot

101

96

Cheekspot gaby

Bay goby

Staghorn sculpin

California halibut

11 0

46 0 13 15

1 0 2

1 0 0

4 0 0

Spotted turbot

Shadow goby

Bay pipefish 0 0 6

1,282 388 972Total number of individuals

Total number of species

5,241

9 8 10

Note: No data were collected during June 1990. The mouth of the lagoon was closed in 1989and 1991 and open in 1992 and 1993.

explain similarities and ditTerenccs between the hi<ila in11'lioral aird COnxtl11C ed «h'in<tel». I lie ini!ili <iring pnl-gram assists C«ilrans, the IJ.S. Anny Corps of Fngineers,and the t.:.S. Fish;utd Wildlif'e Service in determiningwhe hcr c<>nstructcd channels meet the mitigation re-<fuirements I l.:.S. Fish and Wildlife Service Igffft; Table< gl

T<i determine v hether the mitigation cri eria weremet, we used <ndividual-year data to calculate percent-ages. We li~ted the native species tha use the naturalchannel siles and determined which <if these species alsooccurred at rhe cons rue ed channel sites. Note that withthis procedure, the percentage of species present in con-structed channels cannot exceed 100%. Next, we caicu-iated he average density of the native species in the con-s roc cd channels and expressed tha number as a per-cen age of he average density of native species iri thenatural channels. In his second calculation. the percent-age can exceed I 00%.

Giiiichthys mrrabitis

G<relfa nigncans

Hy ps opsel ta guftulata

liy pnus giibert<

Lepidogobius iepidus

L eptocot tus armatus

Parali chthys cat<fornicus

Piueronichthys ritteri

Ciuietuia y-cauda

Syngnathus ieptorhynchus


0 0 3

0 0 13

1.144 222 858

13 I 2

3 1 0

9 38 2

0 0 I

99 108 70

0 1 0

0 4 0

0 0 0

2.3.1 Fish AssemblageF'ish were sant pled periodically ar six stations. four sta-tions in the construcied marshes and two in rhe naturalmarsh Fig. 2.5 !. At each stati<in, blocking nets were used'I<! crea e a saitipling area approximately 10 rn Iong. Abeach seine wa.s repeatedly pulled through the samplearea until tl appeared that all the fish had hewn caught.Through I'P9I, baited niinnow traps were also used tocompare rhe ahundances <if exotic fish, panicularly yel-Iowfin goby IA<-«nrhriffc>br<is fl<r<imar<us! These are thelargest fish caught in the Swee water channels: manyspecimens are 10-! 5 cm long. Yellow fin goby are gen-eralist predator~ and likely affect rhe abundance of na-tive species.

The fish assemblages in the natural and constructedsiles v,ere slightly different: the assemblage in the natu-ral channel was dominated primarily hy arrow goby Ctc<clandia ius! and California killifish Fi<ndirli<spariipinnish whereas the constructed channel wasdomi-natedby topsrnelt Artterin<ips ajfrnis! and California kit-lifish. This difference may encourage the least tern toforage in Ihe constructed channels, because Arherinops

22 TiDAL WETLAND RE STORAT/ON

Figure 2.5 Fishing end invertebrsre sampling stasons.

Table 2.7. Average Percent Cover of Vascular Plant SpeciesCollected Along Nine Transecls at Los Pehasquitos LagoonDuring September 1990-1993

Percent Cover1990 1991 1992Species

Salt mars h speciesCressa truxellensisCuscuta salinaOrstichtis spicataFrarrkenia grairctifoiiaJavmea carnosaMonanthochtoe li ttoralisSalicornia svbterminalisSalicorma vtrgtrr ca

5.489 73

1 5 0 7,822 8 22.7

7 8 5.17.00 4 0.1

52. 3 47,0

7.2 4.817,9 18.51 1.7 1 1.725,7 21.6

4.1 3.34,1 2.10.7 0.4

47,4 47.3

Non-salt marsh speciesAmbrosia psi iostachy aAnnual grassesAtriplex patulaBassia hyssopifoliaGarpobrotus eduhsHaplopapus venetusHeliotropium curassavicvmRumex sp.Typha s p.Unknown Asteraceae sp.Xarr thium s trumari um

0.20.93.10.01.40.0000.65,90.80.0

041.52,40.11 70.00 10.52.50.40.0

0.30.64,40.01.00.00.00.61,50.401

0.40.52.00,02.50.10.00.64.32.90.7

affirii i and F. pari ipi isis are amiing its preferred foods.The comp!i;mce cri eria were met in 1991, when fishspecies and densities had exceeded 7S% of levels inthe natural channels for 2 consecutive years. In 1991,1992. and 1993, all the species hat occurred in the na u-ral channel a!sir occurred in the cons ructed channels Tab!e 2.9!. The total density iif these spi:cies wasslightly higher in rhe cons ructed channels. The abun-dance of exotic species relative to native species re-rnained approximately cons ant over Ihe monitoringperiod !9119 � 1994!. 1he constructed channels of themitrga ron projects complied with the criteria f' or fishas torage for Califonria least terns, and the pattern wassustained through 1994 Sampling continues once a yearto obtain a i ough. low-cos estimate of fish populationsand provide Ca!trans v, ith an early warning of any de-cline tn the quahty of habitat,

2,3.2 Benthic Invertebrate AssemblageBenthic invertebrates were sampled periodically a seven statiiins, six adjaceni. to fish sampling stationsand an additional one in Vencr Pond. All staiions werevisited during January, March, and July in ! 989-1993-Cores werc collected by pushing a cy!mdrical "clamgun" <45 crn long, 15 crn in diameter! into the sedi-ment and then sieving he contents hrough a I- or 3-mm screen. One set of shallow samples � cm deep, I-

RESTORATION EFFORTS QN THE PACiFIC COAST

rnm screen! wa» c<>! lectcd at each station it.hree jars. eachcontaining sieved ma erial from three cores! to estimatethe abmrdances of small, shallow-dweging invertebrates.A second set ot' deeper cores �0 cin deep, 3-rnm screen!was collected to estimate the abundances of large, deep-dwelling invertebra es main!y hiva!ves!.

In 1992, the invertebrate assemblages molluscs,crustacean», and polychaeres! were similar in both typesof channels. Each year we col!ected 9 samples threestations x three dates! from the natural channels and 12 four statiims x three dates! from the construe ed chan-nels. The following rules were estab!ished to determinewhether the data showed compliance with mitigationcriteria: l I! Year-by-year comparison: The numbers anddensity of taxa present in the natural marsh for a givenyear were compared with the numbers and densitiespresent in the ciinstructed marsh for the same year. �!If taxa were present in the na1ural inarsh in previousyears but not in the census year, the constructed marshwas not counted. 13! Taxa identified o species were notlumped into the "miscellaneous family" category. Ad-hering to these rules produced redundancy in soine of lie da a.

Of rhe 41 native species present in the nat~ral chan-neLs, 37 90'7e! were also present in the constructed chan-nels <Tab!e 2.10!. These species accounted for 1,051 ofthe individuals found in cores from Ihe natural channels

Table 2.8, Mltigatfon Criteria to Create a punctfona! Wetland Complex at Sweetwater Ma~shf<fational Wildlife Refuge

f. Tidal channels to provide foraging fot the California least terri and light-footed clapper rail.~ Suitable fish and invertebrate populations shall be present.' 75 /<, of the density and diversity of the prey base, compared with that of an existing wetland that does provide

habitat, shal! be present for 2 years,

2. I ow and middle salt marsh for foraging any nesting areas for the light-footed clapper rail.~ Habitat shall be considered adequate when seven home ranges, nonoverlapping, 2-4 acres, composed of low,

rniddle, and htgh salt marsh, have been established for 2 years- Lower marsh accounts for ] 5 / of the home range and contains 50'1. cordgrass. I ower marsh i«ach home

range contains one patch of cordgrass with a stem length of 60-80 crn, providing 90-f 00'/o cover, that is 90-100 m' in size. Cordgrass stands shall be resilient, that is, established for 3 years and with evidence of nitrogenfixation.

. Middle marsh shall provide 75'I. cover and contain 75'I. native species comparable to an existing wetland;middle marsh should include high salt marsh berms.

3. High salt marsh for refugia for the light-footed clapper rail, accounting for at least 1 5'/. of each home range.

4, Establishment for salt marsh bird's beak.~ Patches of salt marsh bird's beak shall be present within the high marsh for 2 years.~ Patches are considered present when at least five separate patches, each 1 rn', containing at least 20 indi-

vidual plantS, eaoh separated by at least 1 0 m, are Self-SuStaining. Self-sustaining salt marsh bird's beak arestable or increasing in area and number, and present for 3 years

5. Emergent wetlands to provide suitable, functional habitats for the California least tern and light-footed clapper rail,vegetated by 75 /o of the native species currently present in the Sweetwater River Wetlands Complex.

and 3,450 of the individuals f<iund in c<irci ' rom thc c<in.itructed channels. When data were ituiid<irdized andcompared. the number of individual i caught wai grc uerat the constructed channel iites than at the natural chan-nel iitei <24fr<r< !. ln lhc scc<ind year, ! 993, !t5<A <if lhenative ipccici present in the natural channels were alsopreieiit in the constructed channe'!». and the number ofin<lividuali in the c<initructed channels exceeded thosein Ihc natural channcli I S l <A !. Thui, the invertebratec<»nnruiiiliei nicl the;iiieiimcnl criteria in c<iniecu-rive yeari, 1992 and 199.s, ai well;ii in I <!<� ITahlc2. �!.

Althiiugh crabs are iniporlarit prey <if thc light-liiiitc<icliipper rail Jorgensen, I <�s!, coring nteth<ids vied be-fore 1993 were inadequate fnr <tsieiiing their ahun-dancei. ln !993. auempti to trap era hi willi ininn<iw lrapiwere moderately successful, allhough rriany' traps wereswept iway by Currenti <ir Were Suilen. atid <iiice Ihetrapi <vere empty after a very cold night. Overall. etch<tiniei ai many H< rriigr<rpsr<s nrem<<crisis were caughtiii thc constructed niarsh as in the natural ii ei. Earlier.Rutherford �9fi9!, who used litterhag traps v ithincordgrasi-dominated areas of C<inne<ror Marsh, foundsimilar results, Her constructed rnarih silei had 2.5 timesas many crabs ai natural marsh si ei in Paradise Creek.The f993 and ! 988 data seri.iuggest that an abundanceof crabs is available to the light-footed clapper rail.

2.3.3 Long-Term ConcernsThe ipeed wi h which the fish and invertebrate aiiem-blagei met the mitigation requirements refa ive to salt-irrarsh cri eria, cf. section 5.2! indicates that creation ofchannel habitat ii quite straightforward, Our findings areiimi! ar to those of Havers et al, I f 995!, who found sirni-iar fish and shellfish abundances in a constructed tidalmarsh and two nearby reference rnarshes in Virginia. Al-though they found minor differences due to water salin-ity, evidence was scant that ihe constructed marsh wasleis ahle to attract native species.

Two remaining concerns go beyond compliance withinirigatio» requircrncnti. The first is that presence of spe-ciei doei not necessarily indicate functional support ofthoic ipeciei. f3<icumentarion ol lish-support functionsw<iuld require showing thut the ch<tniieli provide toodf' or fiihci ret'ugci f'rom predat<irs. and placei for ee~-e!aying le.g., in<a.'riialgac f<ir attachrncril <il t<ipsnrelt egigs!.The fii<!d-production and refuge functioiii may requirethe presence <if submerged vegetation or heterogeneousmicrotop<igraphy. Such indicat<in <if function have notyet been incorporated intii mitigation rcqutrcments.

A icc<ind concern with conitructed channels is thatthe disturbances associated with dredging will inakechannels susceptible to invasion by exotic invertebratesand that these in turn might prevent the normal develop-ment of hc natural invertebrate asserrihlages. Mtrsctrlista


Table 2.9. Comparison of Fishes Caught in the Natural and Constructed Channelsat Sweetwater Marsh National Wildlife Refuge

Number in

ConstructedChannel

NaturalCha nnel

MitigationCriterion

Met?Year D%%d

1989SpeciesIndividuals

NoYes

133.410

6275

82. 560

1990SpeciesI ndivi du als

YesYes

145.845

Bt178

1310.426

1991SpeciesI ndiv i du at s

YesYes

100284

111.724

1I4.896

1992SpeciesI ndiv idu ale

YesYes

100121

60.665

60. 805


YesYes

54.540

100287

51. 580

1994SpeciesIn div iduats

YesYes

BO86

42.010

52. 330

Note: Species numbers are native species found in the natural marsh and also in the constructed channels;"individuals" refers to densities per square meter, averaged for one to four samples per year Sampling effortwas greater for the constructed channel and differed among years: quarterly in 1989-1990, twice in 1991and in 1992, and once in 1993 and in 1994. Mitigation criteria were that at least 75% of both species andindividuals be present for 2 years.

Lorra>tie t'arsrrns and Jov Zedler

senhrnisia, the exotic Japanese niussel, is common innatural channels, but it is six times more abundant in theconstructed channels. The abundance of this exotic spe-cies relative o native species varied over the monitor-ing period �989 � 1993!; however, it never exceeded I 5%of the ti>tal number of' invertebrates m the constructedchannels Table 2.! I !. Another exotic species, Pataemonmacrodactylus, thc oriental shrimp. was caught in thefish seines and was also common in the constructed chan-nels. These exotic species continue to be monitored todetect changes in their numbers or distribution.

In general, we recommend that functional supportbe assessed more ilirectly than by measuring the pres-ence of species and hat long-term assessment of fishand mvertebrate habitats be done to ensure short-termsuccess is maintained. Activities that could aid in as-

sessment include determining the feeding habita s of

fishes e,g�gut content analysis!, observing predation e.g., foraging success rates of egret» and herons!, andanaiyxing in detail the micro opography e,g.. tidal creeknetworks! and structural complexity of submerged vas-cular-plant assemblages Zosrera marina, Rappra sp,!.including rnac roe lgae.

2.4 REESTABLISHING AN ENDANGEREDPLANT IN SAN DIEGO BAY: Salt Marsh Bird' sBeak

Development of Sou hem California's coastline haseliminated habi a for a state and federally listed endan-gered plant, salt marsh bird's beak Cardyfanrhasmaritimus ssp. maritimus!. Fit'ty years ago, the species

TiDAL WETLAND RESTORAT QN

2 10. Comparison of the Number of invertebrate Assembiages in NaturalTable 2.1and Construe ed Constructed Channels at Sweetwater Marsh National W tdttfe Refuge

Number in

Cons't rue tedChannel

NaturalCha nnel

CriterionMet?Year

1989Speciesind>viduats

NoNo

1228.8

2052. 2

6043

1990SpeciesIndi v iduats

NoYes

25119.0

3679. 1

69150

1991SpeciesIndiv idua s

NoNo

7161

1752.0

2485.0

1992Speciest ndividuals

37288.0

YesYes

90246

41117,0

1993SpeciesI ndividuals

YesYes

85151

29247.0

34164.0


YesYes

75695

676.5

811.0

Notes Numbers are the tolal number of native species and the density of individuals inumber per 530 cm ! in thena1ural channels and the number and denaity Of theSe SpeCieS in the ConStruCted ChannelS. The perCentageS are theconstructed channel number expressed as a percentage of the natural channel number, The final column indicateswhether the funCtiOnal equivalenCy Criterien waS met. See teXt fOr deCisiOn ruleS used tO COmpile thiS table. Samplingutter S in the natural and COnStruCted Channela were different eaCh year. The Severe deCline in indiVidualS andabundaiice in 1994 iS attributed tO the uSe Of alCOhOI instead of formalin aS a preaervatiVe. Rapid deCOmpOSitiOnprevented identification to the species level.

<<.>s '!<>i>i>ii >II I Siiiilhen> 'alii<>rnia ci>list>it n>arstles.iliil «;>s < harl>el«rive< ;is a "frequent" inh;ihi anl <if thoseir> Sii» l!i ' '< '< unly il'urer I942l. N !v, <inly Tiju'«»Iisl«ary s«s ,'tins Its n,'> ural pop«la ><in. Plants al.92 w «et <<,>ter M,'u <h w <'1 c in r<!du«elf <1 fill 'i II a C<>I ranstoit�>gall<�>>1 r<'qiilrenii'lit I t i S. Fish and 'A'>hi lite SerV icelung> ti>l I'ecsi«Nishmei!t <if a selt-sus aunng pop«ist>iu> i>I' hir<l's heiik.

ll> l99 !, PF.XI hegan eff<irts l<ireeatahhSh the spe-cies. Hcc;>use this species had n<> been observed alSwe< «a er Marsh since I 987, seeds v,ere taken fromci>I<>n>es «t Tiluaml Fat«arv and s<>w'n at siies in the marshI'r<im I 99 l lhn>ugh 1993 Bird's heak was initially si!wriir1 4 renliiant h>gh-ntarsh area C<»» rue ed aS part Of hen>itigat«>n pri>jeet, hul genni>ia iOn and seed set <>t' hes<i<sn colony «ere low in i99 l As a result, Cal raus

received approval o move the reestablishment projectio a 'na ural" high marsh south of the cons rue ed marsh.S<>wirigs werc c<>educ ed in four 'colonies" in l99i;ttili.'C were reSeeded in I 992 i B. Fink, pe>annal COrnrnu-ni<.;ition!. I!urii>g I 99 l,ltid 1991. gerlnini»ion andgr<>wlh i!f bird s heak s<>wn:n Swee w'ater Vt,>rsh ap-peal>:0 «. !nlparahie t<! lha Ot' the seed <h!rlnr pupuliniOn;i Tiluaiia Fstu,>ry H. i'iilk, perinnal c<>n>rnunieatinnkSeed Capaule Se . hOWever. wax niinlmai al Several Oflhe Sweetwater Marsh colonies, especially when cornpared with rates <if the seed donor colonies at Ti1«anai=stu;lry IB. Firtk, personal communication: Fink anilZedier I'99I I.

iri I 99 I, seed capsule set reached Stt'A. in somnies at Sweet waier Marsh, but <»her colonies had ra esof 2>tt'i< or less l ink and 7edler 99 I I. Meanwhile, the

RESTORATION EFFORTS ON THE PACIFIC COAST 27

Table 2,11, Abundance of Exotic Species of Fishand Benthic Invertebrates in Natural andConstructed Channels at Sweetwater MarshNational Wildlife Refuge During 1989-1993

Percent InNatura ConstructedChannel Cha nnelOrganism

Exotic fishes caughl inseines

9691990199 19921993

Exotic fishes caught intraps

19911992

1512

912

Exotic inverrebraies19891990199119921993

0 5 9 414

0 817

3 3

Nore: Data are percentages of totals collected.

seed d<in<>r c<ihiriies iit '['ijuana Fstuary had seed cap-sule sel I"ite'< a» high as 9 ! l< Fink and Zedtcr 19'! I !. In19', <iver'agc seed capsule set of I'iliiiils iit SwcetwaterMarsh was ig ic .+ 2'<< l, v,ilh values rariging froiii 0 frlo 75't<. Because th» nun her of seeds produced repre-sents Ihe most relevant indicar<ir ot long-terrrt pnpula-ii<ni change for <niiual pli<nls kicklefs 1990!, tow seedser of C . rrr<rrr liar«» spp. niuri nrnur could je<ipardize ef-f<ins «i e»lablish a selli-su»raining population.

Coriceme<l ah<iuf Ihe i»ipacr ot poor aced-capsuleser on lhc restoration, Cahrans funded a study of t'ac-t<fr» liat affect reproduc»ve potential of bird s beak atS wcct wirier Mar»I , iiicluding effects of herbivory, pol-lination, environmental tac«frs, and intraspecit'ic coni-petilion Or> mOrtality, grOW h, and pro<luCtiOn Of fl<iw-ers and see< capsules. P<illination and the availabilityof nitrogen affected reproductive potential the mos , andadditional research on these tv o facrors was funded hythe U,S. Fish and Wi!diife Service.

2.4.1 Ecology of Bird's BeakSah marsh bird'» beak is an annual specie~ that thrivesin the high-marsh areas of salt marshes ranging fromM<irro Bay lo Baja California. Bird's beak germinatesfrom February rhrnugh March and towers t'rom Mavthrough August or early September, becoming senes-cent sh<irtly thereafter. f<!o study has specifically inves-tigate<i the conditions necessary for breakmg seed dor-mancy in bird's beak. bur germination appears to be trig-gered by winter and spring rains. Opening of dense capp-

pie» ot' VegetaliOn enCOurage» Cspansi<in Of bird S beak Virnderv icr and Ncv nian 1 <!t�. I ink and Zcdter 19911.<iflen crealiiig a niosaic of dense plant eius ers <ir patcheswilhin c iloiiies.

Bird 's beak is a tacultalive heniipari<si e. v hich nieansthat the phint can derive at least some susrenance tromother plant» h<is species!. Bird s beak and orher rncrn-her» ot' the geiius Cruzlykrrrr!rr<» ap into h<!st plants oreven other bird's beak piants through small ephemeralron connections called haustoria Chuang and Heck'ard1971, Vandcrwrer and fs!cwman 19h4!. Plants may re-ceive waier and nulrien s fronr hnst species. but no studyhas <tualirarively determined !ust what type of or howmuch sustenance is received. Fink and Zedter �990b!

found har planrs grown with hosrs produced significantlymore biomas» »ix to eigfn time» more! and ha kf<ururrr!fr> S<rlri <igni <r vrrgrrri< u:Fig», 2.6 and 2.7! However, Vanderwier and Vewman�9114! tound "no observable increase in vigor" in plantsgr<iwn with or without hnsts. Borh nt these studies weredone in a laboratory.

Distribution. Bird'» beak grov s best within a nar-row band of elevation, from approximately 6-7 fr f I.g-Z. I m! mean l<iwer iow water MLLW! U.S. Fish andWildlife Service I9!�, Fink and Zedfer 1990b!. ArTi juana Fstuary, lhe mean ele varion of patch peometers� I ff plots were surveyed in 1994! was 7 � 12 ft �.2 m!MLLW �.04 SE!, Ar Tijuana Fsruary, bird's beak oc-curred in areas with rnicrotopographic relief smallm<iunds 10 � 20 cm high!, tuid planrs were fourid growingboth on top of mounds and between them Fink andZedter I<!'! !b!. At Sweetwater Marsh, almost all plantsgrew between such mr<ands. rather than on iop. Fink and7edler �99 !b! postulated thai microtopography nrightbc impor ant in reducing dispersal of the seed crop whileallowing rainfall rn puddie and dilute soil saliniry. Mor-tality of bird's beak has been positively correlated withhigher elevations, drier»nil». an<i 1<iwer tevela nf clay inthe soil Pars<ms and Zedter 1993!.

At Sweetwater Marsh, Morrarrr!rrr< hid<' !171<rr rlis ac-c<iunted f<ir morc than 110% of the host plant cover in1992. A posi is e relationship rnigh bc expected betweencover of' preferred hosts and occurrence of bird's beak.Hov ever. in the field. aboveground binmass and densityof bird's beak correlated nega»vely with cover of hostspecies Parsons and Zedler 1993!. At higher densities,host plant specie~ may compete withbird's beak for light,moisture, or nutinent s. Relarionships with host plants mayprom<ite wheedling survival and vegerativc grov, th by al-lowing bird s beak lo obtain water from more deeplyrooted species, Soil moisture isscarce in spring, becausetides rare! y exceed 6.5 i'1 �.0 m! Fink and Zedter 1990a!.Ar Tijuana Estuary, only ft of I6 surveyed plots were

Figure 2.6 AbOVegrOund grOW h Ot Sall marah bird'S beak Cordylanthus mantimus spp. mantimus! alone and with six hostplant species Bars are s 1 SE. From Fink and Zedler 1990!

i eblis spicata

anthochloe li ttoralis

amia vi rgini ca

60 <O

Days Since Transportation

Ftgure 2.T Differenoea in flOWer prOduC ian by Salt marah bird'S beak CardytanttiuS mantiimuS SPP. mantimuS! When grOWn With Vaneuahost species and when grown alone Recfrawn from Fink and Zedler 1990.

3C1.

K

g

I

.3 Icr

Ez

rrr ' io C r3 Q

Z y ~ ccr ra 'g 'o

ia

'E8 4. rt

rrf

o

rt

keni a grandifolia

cornia svbtermi nali s

ost

leX Iyva tS Onii

RESTORATION EFFORTS ON THE PACIFIC COAST 29

I .� hail > '.> It �. l inl MI.I-W. Ocspitc ili» inhcr»rit fra-u<fill of' hemiparaii <c relationihipi, bird'i beak ih<w,spl<titter i' iil th<. rip»i ot il!eci<.'i p<u"iiitizcd. I'liii pl'ii-[iciiv lcd yatidcrv,icr a»d Newinan �'!HPI io c<nlcf<i<'k'

ill<<rib bird'i beak diitiibuti<in» a funC i<in «fxti<'>»<> h<ih»ai pr»tet»<lee I"i hei lhiul «I hoi pret»I'<'ncc.

Bird's hc'th ii p.'<tchy. «ccurring ioi»ctiin»s iri high-deiiiiiv a>«upi «>1<J ol »i'I ai <i«lit ed i<id>vidual pl;Irlli.Al hougl'I tilt<<tip<.'Cif'iC C«<lip<.' tilt«ii W«<ild not i»eni tohc,'i prohl»nl tot';i>i c ild<iilgered sp»c i»i. i«ivi<1 gi i<1 I <! 92did crea e patch»i in whi»h ieedling, dcniiti»i r»;>eh»d~2 ! seedlings <feei <neter-. As with m;iny other plaiii ipe-< i<'i, iiicreasing d»nstty did not increase mortality. hut itdid lower the bi<>r»aii ol indivrdual plants Pariorli and7»dier I<!93!. Redu»cd hiomaii can hei> lower flowerriumher and ice<i capiulc ict Parsoili <irld z »dier 1993!.

Requirements for gr<rwth, S<iil iubi raie may beel'acial for ie»dling recruitmen a»d reproductive poterl-tial and iuccesi ai well ln <iur i udy, pl<trit mortal>tv war,low»r in arcai with tnoi>c clay, urldiiuh edly becauie <ifthe higher wa er-hnlding capacity of tine-textured ioils Mcngcl and Kirkby f98 !. Ahovegr«und biomaii ofpla» i «ls<> correlated i rorigly with h:vels of in<irganicnitro<gen in i<iili.

Treatr»enti w itli nitri>gen tert ilizali<>n dramaticallyincreaied plant bioniaii >I�'/< ! ~ foli<ir ni r<igen c<»i-ten �1<!< I, an<I.iced size I g V< 1 and appeared to incrcai»flower nuinbcr '009<! relative to that ot' unfcttiIizcdplan i. When fertilized with ni rogen. plants appeared t<iinvei thcie rcsourcci differentially hy <ncreaiing theiiunlher Of bf<tileh<.'i, »lfi«leieerleei, and flOWei'>i P<li-ii>ni anri I'«rag» prcf-eren ially oii larger plariti and <in plan i with m«re Il«w-eri Parions 1994!.

'I he ialinity of the ioi! did not appear to affe»t per-formance of bird'i beak a halophy e!. Wc do not knowwhe her planti were iubject to itrcis because of ialin-»y: however. salinitici never exceeded .13 ppt in iatu-rated i<iil pastes prepared frommarshi<>il Parsons 1994!.Raiilfall was high during the 2 itudy yeari. thereby de-ci'ciuiing ialini ies in re la i«n to dry or river'<ige ve<iri Par-ioni 19941. In a 1abora ory experiment, bird'i beak plantstreated wi h water with a ialinitv of 3f> ppt had only ailigh ly lov er dry weight than hose trea ed with freshw~ter � ppt! Fink and Zedlcr 1990h!. However, themethod may have also minimized soil ialinitiei, Soil sa-linity wai analyzed by using i<iil pastes Richardi 1954!becauie iome samplei were verv dry. and ialinities mayhave been artificially dampened by resat ura ion <1 ovcri-dried soils.

Insect herblvory. A primary insect herb<i"re of i" 'marih bird'i beak at Sweetwater Marsh was t"e larvalstage of Lrl>ogrupiri 1 fencsrretf<r Pyralidae! or salt marshsnout moth. This same speciei hai been observed f«ag-

ing oil hird'i h»:ik It> 'lijuana Ei uary and Pi>tnt Mugu N«ano,ind Houuc ! 982. Parioni 1994}. While darn-:ig» o planti ol' en <ippe;<red extensive. a Sv eetwaterMtirih. gr;iniv<>ry e;iting «f seedi by larvae! did no 'idv»riel! af lee h» pcrcelitage ot flowers pn>due<rigiced capiulei, the percentage of flowers producingi»at<in' <ll' ><rid'u'I'i;tged i»»d CapSulei, Or the number Ofice«i pr<xfuccd per c;ipiule Parsoni 1994. Parsoni and/»dier f9941. Iri niany caiei, ci eii iced capsulei ihow-ing iigiii <it grailiviiry i.e�bored holei in he.iced coa !i il! r» ;iiiied undanlaged ieedi.

Gruiivorv <vai extremely variable at SweetwaterMarih, devaitating i«me patches and mini<nally affect-ing otheri. Thc reaion t'<ir thii selective pattern ii notknown. hu graniv<iry ihov ed a hig>hly significant rela-Iionihip v ith flowering tiine of pa chei. Early flower-in<> pat»hei late April trc seedpredation th;ul la e flowering onei tia e May to earlyJune! Parsoiis 1994!. The phenology of theie earlyflnwering plariti may coincide rn<ire closely with the<ivipoii ion cycle ol' the egg-laying micropyralid mo hthan that of th» later flowering plants,

Pollination. In.iect i <ilio Play a positive role in popu-lation dynaniici of bird s beak. Ai an iniec -pollinatedaiinual. hird'i flak relies primarily on insects for re-produc ion. Th» niain p<>llinatori <>t bird's b»ak appearto be he»i from he genera B<>t>tbris bumblebees!,fr<<It< In<, L<>xi<>e!<>sstrm. Anfl>idium. and Me/i<Sr>dea U..l, Fiih and Wildlife Service 19�4, Lincoln 1985,Parsons f994!. Low rate of iced Capxule set a sO ne»oloniei, conihined with observations of' few pollina-t<>ri. led Fink and Zcdlcr �9911 to postula e tha a lackof pollinat<iri could be limi ing iced sct at SweetwaterMarih. Devel«pit>en ol adjacent upland areas may have»lirninaied neiting or alt»motive foraging habitat toriniec pollinatori. In b<i h 1992 and 1993, treatments toiupplement polliiia ion hand pollinationl sigriilicantlyiricrcaied iced capiule ie . Hand-pollinated plan s set89<!< morc and C2<!< morc seed capsules than naturallyp<illinated planti in 1992 and 1993, respec ively Par-sons 1994I.

Sheer abundance of pollinatori did not appear to beai importan lo pollination succesi at Swee water Marshas the relative abundance of' pollinating species. Plantsin patchei viiited by either Bar»I>te< and halictinci orMeli<.x<><k'» and halictines had higher rates of seedcapiule iet than plants in patches visited by halictinesalone Parsons 1994! A>tilt>'<li<rm edw<rt'dsi > ~ character-ized ai the m<ist important pollinator of bird's beak atPoirit Mugu and Tijuana Eituary, was not observed atSwee water Marsh in either 1992 or 1993 Parsons1994!. No hiitorical information is available to indi-cate whe her A>rrhidinm was preient at Sv eetwaterMarsh when the historical population of bir'd'i beakexisted.

Results from the hand-pollination treatments sug-

gest that. generally, low leveli ot pollinati m nlay havehad the in<iit Impact <in reproductive succeii <if' bird' sbeak al S weel Water March. PrOX>mi ty if pl anti n>ay haveanccled foraging behavior morc than resource abundance.Polliitator viiili ih<iwed both a strong block patch! and«luiter lgr iuped vs. iiolalcd patchei! effect bul did nolcorrelate with the density <il' infliireicence Pars<ini andlardier 1993!, Polltnaiorimay pret'ereniially viiii palchci<in lhe haii» <il proxies>ity t<incsti or cluilering, if'patchesrather thitn on thc hai>S if the amiiunt <it ll«weri With>na patch. ir piillinaf<iri may iirnply cnc<iunter clui>eredpal«hei m<irc <iflcn than iiolated onei, regardlcii of thenurnheri if f1<iv Cri preSe>il. EX«ept f<ir It<>nth«<, mOS Oflhe bees p<illinating bird'i beak are Ihought to nei nearI heir I «raging iiiei. kaliCtine and Mcli.e <><les bcei huild<><.iti hehiW griiund. Whereai Atirltidit<ni and 8<In>lrit<huild nciii in precxiiting cavities, either ah<ivc or belowgniund lLabergc I < 6, Stephen el al. 1969!. The density<if nlll<ireicerlce did a lect ihe «»miter <if pli»tli viiitedperp;<tch If'arions a»d/~ II«r l99.3!. P illiiiat<irs preferred»iediu»>- ar>d I;Irge-iiacd plan>i i i i»l;tll <siei, pr<ihahlyhcc Iuic h« i<llilii ' irrchitcd p»i>iv 'ly with ll<iwcr nunl-I>CI II'a<'i ini nld /iedfer 1993I.

2.4.2 Monitoring for MitigationReqUirementsIn 199 . live iiici, cauli ciintainiiig live imall patches ofliir<l'i lic;ik. crc i«le tcd f<ir arinu;il moniloritig atSw IC»ici'Ili <»Itl iii«d It> >he »la ig:It><i l I Iii <Ilxti>!. I» dcr ICI'I'nii'IC lllc ni iil: C«»-IIII ' i<»<l 1»nc <'II<«I«lll »i«ill<sf <!f I'n<'»'Iiloilng hint'.i beak.ihtcc ii»» filitig Il<cth<idi < CI' Iiicd»i 3<IIV I '!93 > I<iice<inIi,;I>td p<iii>l-qitiirrer If'ario»s;In<! Zedfei1993! f3«c;I»i«>bc d<iirihuli m <if biid'i ibc,tk ii patchy,In«th<idi vcr« i«le ted Iil> if>c hiiiii <if IhC>r.ieni>tivity t<irl<i<lr;u>d<irn diiir!hul»ini, ii»0 c<irrecli»ni f ir 'lu»1peddiilrihuli ini Cre uiCd il;Ivail;Ibl». All iiplii>g nieth-odi, Il<» evet. d i itiiti»><.' >a»dna'I d>i>f<hutinrl of large>Idpistil ipe Iei, W h>ch C<iinpliCatei pl'int si n>p!ing. Ai it«<intr<if. all pl<it>ri <thin Ihe arC;I delinii ted f!y Ihe Outerpcrrr>icier iif' rhe live designate f patchci wer'e c<iun>cdthree Iiniei, and the three «aunts averaged. Theie nurn-beri Were then COrnpared With eit tmitteS Ohlairied by ui-irlg the i>he> three iampling n>ethods. When compare<jwith total c<iunl averages. numberi of bird's beak plan>i

werc undcrcitimated with a!f three iarnphng methodssomelirnei hy a factor of 100 or In<>re Pari<ins and Zedler1993!. Therefore, an average of three total c<iun s iif eachgroup of patches was used for moiiitoring the nuinbet ofplants pre icnt.

A 3-year period with a lcait 100 planti ii requiredunder the mitigati<in agreenient Table 2.13!, and theccniuiing of bird's beak began in 1993. Wc estitnatedpopulation size and the total nun>her of ieedi pr<iducedhy plants present >n both 1992 snd 1993. Unfortunately,we could riot determine germination rates, because iced-lings may have come fr<1m seedi sov n by Fink in 1990.1991, s»d 1992, ai well ai f'rom seedi produced by thenew population of plan s. Seeds are known to retnsin vi-able fOr <nore than s year.

The five sitei all exceeded the rriinimal require<nenlof 1 X! plants in both 1993 and 1994, with more than 1.000plants <n the monitoring area in 1993 and more than 2,0IOin 1994. Estimates of the numbers of plants in lhe entireSw«etwalel Marih were <nore than S, XX! in 1993 andmore than 14,000 in 1994. These estimates i>>elude plantsat the originalsowing iite southernmost ConnectorMarsh island! and two silei in the northern ConnectorMarih islands cf, Ffg. 2.5! that were iiot planted. Al-lh<iugh plants at the last two sites were nol nurnero»iI�00 in 1993 and about 500 in 1994!, their appearanceindi«ates potential for spread into cons rue>ed marsh hahi-tali, al least where hail plants and good ioils oCCur.

The main problem in the constructed marsh is thatIhe suitable eleva ioni tend to be unvegelated, liighly sa-line flats. Average .ialinity in these hare spoti was morethan 130 ppl in August 1994, compared with 46 ppt invcgela ed high marsh. Thus, while reestabltshrnent <if'bird i beak in remnant high marshei appears feasible,developing a selt-iustaining population in constructedmarshei, especially those on sandy dredge ipoils. ii leislikely. Attempts to do so will begin after 1995, when weanticipate that the mitigation criteria will be met and seedican be c<illected and sown al Marisma de Naci6n.

2.4,3 Implications for Monitoring andReestablishment of Bird's BeakRecently, Schernike and colleagues �994! argued thatthc "rcie;irch reconirnen<f;tti<ins for federally listed pl anti'II«. I» genel itl. II !l itttl le le>ll l reqitired tvery guide-linei." '1 hey advocat» a three-step approach lo i udyingrare and eridsngercd pla»li. determining I ! if lhe popu-lation iixe ii increasing, decreasir>g, or stable, �! whichlite itagci have lhe greatest effect on populati<in gr<iwrhand species persistence; and �! the biological causes ofVari,ltiOn in th<>ie stageS>1>at haVe a majOr dem<igraphiC>nil!act.

hiiple<ncnling this apprOach is difficult. In lhe caseOf C. mrJI I>irma< Spp. n>urtt<t>tt<S, We COuld nOt determinelhe most cri ical life stage. Because of differences

}!«I «ei> v«ed L'.i}i iile l!iiidu«tiiili at S cet w lifer Xiii>la}>iii>d Tijuailii L U irv. h t«g tl>;>t i» 1}ik ly icgulai xi>iiiiil>crx i!t hlld v lieak 'I Sv eel»;It 'I 1 l.irs}> w;i v te<}v«I !«I lo IL'I'I e I»»lite ' it xce I pl id i lli!l'I I'I'l<!I« Ihiui7 X!. III I »> lu'! t ail94};>Ixo vuggevl th;it e rn»niti<i»p};I ,I «rue«>l nile»> regula »lg pi}!ul:itiiiii xise iil her }'xhe;ik 'll Sw '«I ill 'I' h1'u'vl> I P Irx i» 'I>id /C }I«r I ! >a}.

I !ii'lii l i I'lelcil» ill« Ih«pop i I'>i>i!» I/« I«iedi d I»I lol'Ig-ren>> periiv>en«e;Ire Unaviill«hie. Aiir>u;llv v ith per«i«-IL'I» VL'e 'I h !ilk«, uc}> il }!if'd v hc;Ik. pr»h;IIEIV CXperl-CIICc;irlr!llal I1uctuat«»1 l.»tlg-tell» I»I!»l iilil'Ig W !uldhe»«Cd«d tt> d 'ten»ine it' he pOpuLIII<n> Lari xurvive yearvill x ' ' 'IC Covin!fit»i:otal xli ex«, 'llld ICW I'evC«I«h Or»1;ifl-,>g 'n>«i>t pn!jcctx h;Ive the ne«equi»ilry hudgct or life xpai>.

iullting }Eliul iv r>iit enough. IEt;In >get nee<} tii he;>hie iii p>edi«l whefl p !pill ation de«l»le« lr>dlcale xi!n>e-thing i»i!re th u> i»ter iru>«al varialiility aiid ii«<irrect lii»-! >fig I;>CI irx hC irC the deC}ine he«iir»ex irrever }hie.} IE ur»>g 'Ide iu'lte p !ill»if li»1. x«ted pr»duc IO», laid gei'-»l»>il>«»»x critical t ;ilnl»g h>r }'x he;ik il S v'eetwiiter cari}>. Co>>xerviltion ol he v}!c«icv re }aire >hat Ihe ex<en ial hce «pe«iex have ui iih}e hahit;i iiearthe n>arxh, lh;it natural pniee xe that vupply i>u rien x ti!thL high n>arxh he de err»ined;ir><l rcv ored, lh:» Ihc n;itu-riil ~a}if>ity rc iti'Ie he xuvtaincd. aiid th;>I naiural dix Ur-h fn«es Ih; <ipe» re>all-xc«le patLI>ex ir! 11>i. high-nuirxhcan ipy he prevent.

2.4.4 Recommendations for Introducing SaltMarsh Bird's BeakFuture CIY<!rtv ti! irltro tu«e x;lit i>sarah hird'x heaL I ! vite where i »I«c CXIX ed 'il 1» C»I> true ed Wetlandx m;iyhenet>t triin> the t'iill iwi»g re«of»»>c» }:I ion«;

~ SCed-xi! v ing defixi iex vhou}d hC CnntfOI l«d IO «VOid

lilt r'l pi! ' I I I««i!fllpel it !i! ll .. iii I I'Ig xl'I !» I I,'I .'» »I t IIintern>ediiite Ic>i ifi«i � I S� ~ec }Ill>gv/ te«i>EIC-Ier !, }!C«:»l «vi!«h di:» I'IICV l»,i'! I».'IX»»lre hio»1-ilxx Vill«!Ill tov»>g lh«pl'iidile lv ltV 'ixx i«lii « 'I w ithliigher i}eiixitieX. High dei>xiticx oI I» '}»rex«en«e~within pil Chex 'li'I I'I 'it ilppC>lr»C«exi»irY } il',>1 r<li.'-Ii<!» il' p<! i}i»iitiirxS cilx all !ill1 hiixt pl;ult xpCC>Cxxhouk} he COI'I«Id«I�«d vvhe» CI'L",>'I»lg p<llche!L Pn.�ferred h ixtx inc}lid« f!ixfi 'hti ' .�!f< istic,Mrisussifllin'Ill!i ' tiff!!!<gati . and.! sir«irsfi s i Is xiinii'is.

Thl>>>>ifig may hc i>ceded t «get« i<in;md Cn« iurage eXpiln-xiiin ot' hird'x heak. Ciiver if pot«i>tial ho«t plantx«holi}<} niil hc I<'iii Icf>xc. he«i>«i C lt »1«y C E»lpe'Ie vith hird x heak h!r hghl ol othi:r lie«our«ev.SLtcd hou}d hc xowi> at e}cvat«inx hct ecn 6-7 tt I.S 2.1 n> I MLLW iln } where xi!il ix liigh in clay«ll t low I» <If l 'I.A link hetv ee» lhe p}ai>t'v high-»>;ir }E h«hi at andup},»>d areax nccdx tt. hec;IU e uplandafL'ilv 11»ly 1!C u cll t»l »CXI>t>g a» J I»I'lglng hy' Irll-pi!rtant p<i}lii>atorv xu«h ai Bnfrsbfs!. Further re-vearch lx needed to clarify the next ing re }uiremen xol pollinat<irx in i»>It n>arxhex.I}c«au e !f thc xeilxitivity if rnoxt vegetation xam-pling me ho }x t i pat«hir>cxx in pbnt dixtnhu ion,to al c»un v vh<iuld he uxcd t ! axxevx i>umhcrx nthird'x heak within gr<!upx ot patchex xelecIed form<in>1<ir<ng. Ciiui>tv should he diine in late Jur>e toearly July, v hen i>>ii t plan x have Lorripleted veg-etatiVC grce oceurx,

32 TiDAL WET! AND RESTORATIPN

2.5 LESSONS FROM CASE STUDIES

DuPI u, rl I h no'I l I

Table 2.12 Criteria for Compliance with Mitigation Requirements

Warm Springs Marsh ~ Provide flood protection~ Improve water quality~ Provide for public enloyment~ Enhanced habitat for wildlife, specifically pickleweed

Salicornia virginica! habitat for the salt marsh harvest mouse Reifhrocfontorn ys ravivenfnis!

~ Return tidal flow to the site~ Enhance the habitat for wildlife use~ Manage the reserve as a least tern nesting area

Bair Island Ecological Reserve

~ Create cordgrass Spartina folioaa! habitat~ Create open water habitat for waterbird use~ Convert most of the site to a tidal salt marsh

Hayward Regional Shoreline Marsh

~ Return tidai flow to the site~ Establish a self-sustaining habitat for waterfowl and shorebirds

Muzzi Marsh

~ Replace lost shoreline, subtidal, and intertidal habitatsHumboldt Bay Mitigation Marsh

Salmon River Estuary ~ Return tidal flow to the site~ Return the estuarine system to conditions existing prior to diking and

agricultural use

~ 50'/ use by luvenile salmon~ 5 !'%%d use by waterfowl, shorebirds. raptors. and small mammals~ Transplant Carex iyngbyei~ Monitor for tive years

Gog-Li-Hi-Te Wetland System

~ Construct a saltrnarsh habitat to meet the no-net-loss pohcy of theCanadian government

Pacific Terininals Saltrnarsh

In this section~ brief case studies of nine restoration sites ranging from California to I3ritish Columbia arepresented ManaRernetst goals for the eight sites being undertaken under mitigation requirements appear inTable Z.I2. As the review will illustrate, unanticipated problems made these goals d!Ncult to achieve in everycase.

Indi~idual Iessons are drawn from each study, and generalizations can be made for future rest<irationefforts It should be evident that it is difficult to duplicate the most basic determinants of biologicaf systems�namely, the hydrology and substrates of natural wetlands � when managers have little choice of location ormaterials. It is also evident that most restoratum efforts are inadequately documented, and that detailedscientific studies have not generally been made. Further, although we have some idea of the problems thatarise during restoration, their causes and biological impacts are poorly known.

The great poten'tial for restoration activities is suggested by Iong-term observations of constructed ortnodified wetlands that show use by native species, A reasonable conclusion is that we can create habitat, butwe cannot always predict what it will be like or «hat species will benefit. There is obviously considerableroom for improving the predictability of wetlands restitration and creation.

33R[ STORATION EFFORTS ON THE PACIFIC COAST

l.iis venasquit<ts l,agonn

l.rssons: 1. An adaptive management progri m is necessary to track <Eater <iualitv so the ocean inlet canbe opened and fish kil!s av <tided.

2. Vre<tuent sntall-scale interventi<ins build<izing he ni<iuth annuallyl may delay or eliminatethe need f ir massive dredging.

Warm Springs

Lessons; I. The nat tire and direction of hvdrologic changes cannot be predicted with certainty.2. Monitoring is essential in wetland management.

and sa!t harvesting. Pumping of groundwater, whichcaused compaction and oxidation of the marsh soil,combined with discharges from industna! and sew-age treatment p!ants, created a highly degraded con-dition Williams and MOrrisOn 19! 8!.

The restoration plan was developed to facilitatethe evolution of a natural marsh with as little humanintervention and maintenance as possible. The broad

The project to restore Warm Springs Marsh, locatedin thc southern part of San Francisco Bay Fig. 2.!t!,was a cooperative mitiga ion etfort of governmentalagencies, private developers, consultants, and an in-dependent environmental group. Originally consid-ered high-marsh plain, the 100 ha site chosen for res-toration was located within an estab!ished salt marsh,For 40 years the area was diked for agricuhural use

I.OS Iieft,'IS<!alt<is is ii I i lative!V siii'ill i'stu;Iry 142 lia Iiri rtiirtliCrn .'ian DiegO Ciiunty liat Is tl'Ciliieii lyCliiseil tii �<t'II llilshl<tg. Ait 113!c -d< edgliig 1!i <iai 'IAEEhas been ilevelopcd t spe-cies ot est uannc plants. invertebrates, fish. and birds.SevCr.<1 sensi iVe SpeCies «rC prevent in ihe I;Ig<3<in,including nE<iderutc p<iputati<ms iil' Ilie t'iiultcr go!d-1'iek!s L<rxrh<V i«X'I«tuft« i n<<lr<'rii anil the endan-

uercd Bclding s s'iv'at<lab sparrow.TIEC illaIIE eltvlt'O<EIEEental prOhlem ai the !ago<Et

is the fre<tuent closing ol he»touth hy beach sandand ciibble. These c!osings cuusc widespread dam-age in the lag<sin. eh<nine! waters ot'ten become stag-nillrt, leading hE extensive ki!IIAg of !is iiitd invertc-br < es. The subse<tue<E aCCurnulalion Ot inOW s Cancause thc sa!t marsh o become llii<idcd, makiiig itunsuitabh liir breeding birds and causing the deaths<il tital'Iy p !i<lit!I <End thC 3'llminat<ci'n iif s<iilte specIes.

In !9t s. an enhancemcn plan and program 'wii'iprepared hy thc Los Penas<tui os Lagii<in F<iundat ionand he Calit<irnia Coastal Conservancy, 1'his plant'<ieused <m sOIVing the pr<>h!em Ot the fre<tue<E ntiiuthclosings. It was es inta ed that the !agoon had been itidal eiuuary in the !92 !s hut that C<nistruC iOn Ol' arr<ilr<iad and a road thrnugh the CS uary in the earlyI'! X!s had al cred the hydro!ogy to such an extentthat ehh tlows cou!<l no liiiiger maintain u in<ruth ch.ut-nel. An extensive dredging program designc<l to iii-crease he ida! prism could have been undertaken,hut his wus c<insidered too destructive to the exis -ing envir<inntent. Instead a Cau inux and eXpertnten-tal approach v as used to restore idal tlow. By 1992,a strategy had been developed that resulted in the

iii<iuth < 1' the lagii<in being < pen 11 of I mi nths.1'liii rcsu!i i ppcars t<i bc i!tie t<i ii butler apprcciu tortiil Ihc O'ICC�'lliisnis ol sedi113e<31'l IOIE anil�3<i the

I I 'I I iu I iTlie he:Iehex arOund Liis peftas<!ui OS Lag<<<in are

Coi»piiseil Ot' suit <i iiverlying ciibhle. WimerS urmv, aves remiive the s;utd 1'rom the beaches and depositIt in hc snhttdal area. thereby exposirig the c<ihh!es.The a<nailer waves ot spring arnl summer return the<autd to he b ach and cover up the cohbies Kuhnaiiil Shcpard I <!t�!. The m<iuth iif the lagoon i» partiif !its ilylta<EEIC aysteltl. DUI Iltg thi'. WIIE er. Ci!bbleSare pushed in o the mouth channel, a<id during spring<<ltd suIEETIEeI, saltd tends O COVer thCm. ln the 1980S,thc cobbles I'ormed a sil! ni he m<iuth at approxi-niiitely mean seii level ha prev<.nted sOnie inllOWS.slowed ebbing llows, and formed a paviiig on theh<inoiii of the channe! that impedeil er<isi<in. therebypreven ing the ebb t'iowa from creating a deep, long-LES ing rnnuth Channel. The rn<iu IE generally C!Osedsoon at' er he winter rains when sand began to bedepiisited agaill.

L<is Peftas<!uit<ES LagOOn FoundatiOn'S apprOaChin the ! 990s has beeii to remove the cobble si! I at theIiiou h. During the springs ot 1 99 i � 1994, cobbles inthe mou h channel were renuived by using a hig-whecl fr<nit loader and a self-!<Eading set aper, iind!<andand c<ihh!cs <sere deposi ed <in the beach approxi-ma cly 2 X! rn south of thc m<iuth.l he work usually o<ik C days. The ni<iuth of the lagoon had been openapproximately 2s'!< Ot each vear during the !980s,hut it was open 48ct< of !99!, 95'i< of !992, 9!<yc of!993 1 Roland 1993bl, and at least thniugh Septem-ber 1994, Be ter tidal flushing has led to severa! habi-tat impr<ivements, particularly in water <Iuality,

ObjeCtiVe waS O Create a Syc C<n capable Of prOVid-ing the func iona characteristic of wetlands, that is,flood protec iim, improved water quality, public en-joyment, and habi at for wildlife. The design spe-cifically focused on enhancing pickleweed habital,home to the endangered salt marsh harvest mouse Reirhrod<>!rr<!myx ruvi i entrisl Williams andMorrison I 988!. In I 986, excavation created a con-voluted shoreline and a large embayment separatedby peninsulas into six lagoon cells Abbe e al. I 99! I,and northern and southern levees were breached,joining he site O the eXisting niarshes,

Moni oring was not a condition of the originalpermit. In response to an obvious need for docu-mentation. a detailed monit<>ring pr<>grum thatsparuied I years was subsequently funded by the SanFrancisco I ound;i ion I Williams and Morrison}9881. Ci>ndi tons existing before breaching andcharac eris ics of the rest<!ralii!n were doCumentedal least twice. Var!ahles examined included eleva-lions and cross-sex ious, tidal pa ems, salinity, chan-nel erosion, sedimcn ation, tidal circu!ation, and useby plants and animals,

The substan ial increase in the voluine of waterentering he southern part of the lagoon caused highrates of sedimen atii!n. Surveys of cross-sec iona ofsou hem and northern lagix!ns showed rates ol sedi-

IIair Island Ecological Reserve

l.exxon: I. Management goals may be slow to evolve.

One hundred years ag«. Bi<ir Isla<!d was a sall marchin the soulhwecicm part iif Sai!Francisco Bay. PartsWere tlien <like<! f<ir;igrieuliure urilil 1948, at WhiChtime n!<!c iil' llie rem'iining island was diked for salt<.valx'ill<!ll p<!oils Iii I <J73, Ihe I<< id Was acquired byMi!bile t!<l I: s a ec. Tlie Cali i!niia Stale Liiiids Ci!m-in!a>n<ui i!hlilnlcil 324 hil i>l lie isla<in Th» l!ep;!rouen >I Fixh ari I Gaine "ile-lenlillleil liii he site was a unpor aril h'ih<tat li!rwildlife arid,'icccp cd a le;<se wi h niaii;igcnicn re-sponsihili iec li>r lic ci c" Jiiscelyn ei ai 1991 h lnI 974, an agrceineni w;is niiule hy M<>bile Oil Estates.the Depanmen of'I.i ah and Garne. and thc Sta e LaridsCommission to conduc a comprehensive 3-year studyof Ihe environmentally sensi ive areas within the site.including "re«ommenda i<ms <in he fu ure use and/orpreservali<>n of' such areas" Josselyn e «I. I 99 I !. In1976, additional acreage wac donated by the owneras mitigation H!r the development i!f former marsh-}ands.

Environn!en al reports indicated numerous ex ist-ing and po en ial wildlife values. Restoring tidal flowto the site and recreating a salt marsh habitat further

34 TIOAL WETLAND RESTORATION

mentation he ween l. I rn/year and 0.2 n!/year, <e-cpeciive!y Abbe ct ul. I'99I l,

Pickleweed Sufi< orr>iu virgiiii<ul, tat hcn

A r<pt<tr purulul, and COrdgrasc <cpu>ti>!u f<!l <rru!seeded themselves. Pickleweed c<>ver has increasedwith time iri the upper eleva ions; corderass has re-placed pickleweed in he lower elevations IAhhc etal. f9911. In l 990. 4 years af'ler he initi il breaching,il wac apparent ha vegetative coloniza i<m and dist-ributionn were responding to hc changing physicalcondilions of thc site. In 1988, Williams and Morrisonobserved that "over 70 speciec of birds } use } the res- oration cite, including Hocks of white pelicans feed-ing, and he peregrine falcon designated hy the 1'ed-eral government as an endangered species!.' Threespecies <>f fish use the constructed channels for breed-ing, and several others have been observed in the area,Harhiir seals have also been seen in he embayment.

A» the cite evolves wilh the changing flow pat-terns. monitoring hac shi!wn unexpected "feedbackresponses no [antiCipa edj in the origir!al design" Abbe et al. I 99 I !. In 1991, the state of the ec !sys-tem was s ill considered dynaiiiic and its future diffi-cult o predict. "Continued monitoring of the resto-ra ion [is} cri ical in assessing the relative perfoi-mance of he cite as it was designed" Wi}liams andMorrison l988!.

enhanced the cite's value" Josselyn et al. I 99 I I. Be-tween l973 and 1976, the Department of Fish andGame discussed options for restoring tidalaction toparts of Hair Island. In l976, an unplanned breach inan outer levee flooded a large part of pond B l. As aconsequence of he winter storms and prolonged ar-gume<u. baseline data on the physical and hydrologiccharaC eric ics of he area were never COlleCted. Like-v isc. an a tempt by the Calif'<hernia Conservation Corps o ransplanl cordgrass pers. the U.S. ArmyCorps <>f Engineerc iSSuCd a pernii Ii! manage theCite ac a least e<n nesting area. ACtiVe ii!anagementby the San l.rancisc<> Bay Bird Observatory began in1980. In the nexl 3 years, different s ra cgies wereused o enhance the nesting site. By I 983. il seemedthat terns showed no preference for a particular con-structed nes , and nests were found in a variety oflocations Joscelyn et al. 199ll. That sa nc year.concern for the erosion of levees .surrounding thebreeding co! ony resulted iii numenius confhcting pro-posed solo ions. Thc plan t» construe an internal

35

Figure 2.8 I ecaiions oi San Francisco Bay marshes tar case studies

thmugh the levee separating the tu:o major ponds.C!radua!ly, picklewecd and cordgrass colonized thearea. Vegetative c<iver increased from 73 acres in1982 to �C acres in 1988.

To date, four federally or state pro ected speciesand three species of special concern have been foundwithin Bair Is!and. Most of these have been selectedas target species f<ir thc management goals Josselynel al. 1991!. The»alt mar.h harvest mouse has suc-

ces»fully been trapped on and adjacent to the site since1971. In a survey in the <vin er of !993-1994, sevenCalifornia clapper rails were observed within theReserve C, Wi!cox, personal cornmunica ion!.

Hayward Regional Shoreline Marsh

I.essons: I. A large buffer zone is required to facilitate even limited use by wildlife.2. '<>tow establishment of vegetative cover may encourage invasive species.

ln 1973, the City of Hayward purchased a largepart of thc site to create wastewater oxida ion ponds.In anticipation of plans to further develop Hayward's13 km shore line, several Rica! planning agencie~ pre-pared land use report~. Ca!trans funded the proposedmarsh restoration whose primary habi at ohjective wasto suppon the establishment of cordgrass. Secondarily,the design incorporated large areas of open water to

levee was finally agreed on. Unfortuna ely, thcproJcct has riot created c<inditi<>n» as plaiined Josse!yn et al. ! 991!. No least ems have used thearea since ! 988. Deterioration of northern levee»threatens t<i drive Caspian tern» from thc area a» well.Currently, predation hy red foxes is a problem. Large,parts of heron and egret rookeries werc destroyedhy red foxes in 1991, In an a tempt tii attract thesebirds back t<i the re»erve. he U,S. Fish and WildlifeService proposed to u»e "c<iniidence" birds lor de-coy» 1 in the winter and spring of 1994 � ! 99.'S.

In 1983. a decision was niade to increase tidalf!ows to the adjacent pond 182!. A channel was cut

The Hayward Regional Shoreline historically was lo-cated on the site of Crystal Salt Pond and an cxis ingmarsh!and. The project to restore the shoreline be-gan as mitigation for the construe ion of a new bridgeacross San Francisco Bay, Between 1865 artd 1'927,and again during World War II, the site, which con-sisted of more than 81 ha, had been used primarilyI' or salt production.

36 TIDAI. WETLAND RESTORATION

Muzzl Marsh

l.essott: Amelerati<!nof restoration may depend on the placement nf dredged materials.

encourage use by waterbirds. In 191�, extensivemovement of earth and dredg tng of the channel weredone. The ultimate goal was o convert rnos of thesite to a tidal salt marsh similar to he one that prob-ably occurred under primitive condi ions Josselyet al, f987!.

A 15-month study reported in 1981 Josse lyn andNiesen 1981! found no natural establishment ofcordgrass. Natural drainage channels had not devel-oped, and large areas of he restoration site containedstanding water. In 1983 and 1984, cordgrass culmswere planted, but esrablishntent was slow. Erosionin the natural marsh was also gradual! y reducing thearea of vegetated marsh there Josselyn e al. 1987!,

From 1986 to 19117, field studies compared theHayward RegionalShoreline Marsh with a naluralmarsh in <!an Leandro Bay. Da a were collected <insoil and vegetatron condi ions, bird use, and fish abun-dance. Vege ation in the natural marsh was dominatedby perennial we land plants andby a "preponderanceof' algal mars" Josselyn et al. 1987!. In contras , therestored marsh had many more annuals � of 12 spe-cies! and nonnative .species � of 12k and no algalma cover. Cordgrass had begun o colonize the openmudflats; however, iri he 6 years since work had be-gun, he ci!ver of cordgras» was less than 10~~< Jossclyn and Duffield 19g7!. Pickleweed replacedcordgrass a the upper edges of' the marsh. Lov veg-et<ition cover was though o be a result ol' low soil

For I S years h«tore its rextnra iOn, the Si e Of' MuZZiMarsh was diked and used for rhe deposition ofdredge sp ii Is ii! cre;nc sites lor commercial develop-<n«.' ll. Re«<!r!<if'u<' !un ol' the hi su!riCal eleVa ion in-di«ates thiil by he n!id- 197 fs the area had subsided !. I 7 ili I I,!h'!g'!r!;!nd ltrv;uil «I iil. 1994!. Resto-ra ioi! hcg,!rt,» p;irr iil'll r»i igati<ui pruje«r I'<ir dredg-liig a fcrrv .!<'«css «I ann«i Illr<!ugh the C <!r < Madcr;iiudll'<Is, AI the hue, "hl IC < ils hri<!W i rihnu liephysi«;d <ir biologi«al pa<i«esses <!f in<a sh res ora i<!n" W!Ill <r!!s ct «I. I <!Kg!. Ifo«ever, puhli«support I'<irecol<!gical issues v <is rapidly growing. In I <>7 !. IhcBay Conserv,! ion;!nd Develupnl<.'i<t o<11111< Ss l<in iS-sued a p rnil Io c<uls rue lvhizli Marsh. Appr<!xi-matcly �3.4s I cubi< n!eters of dredged niar rialswere placed in the upper parr ol the m;<rsh and thebay<vard parr of h . si e Gahagan and Br> an et al.19941, and levces were breached ro rerum id!I flow sto 53 ha of former we }ands. This marsh was one ofthe flrS SuCh rextOra i<ra prOjeCts iri CalifOrnia, andits evolution has been n!onitored with grea interest

moisture and Oigilrll««onten .P<ior development of sinu hs and <.hannels and

high rares of sedimenta ion in the restored marsh lim-ited i s use by juvenile fish. Th» greatcs diversity oflish species was supported within <!an Leaii lro Bay.Hayward Regi<mal Shorefir!c Marsh was pri�1arilyused by r<ipsrneh.

The marsh at Sar! I eandro IIay gener<I y hadgreater water dep h at all tide stages and n!ore pro-tec ed coves than the shoreline marsh. Shorchirds atthe reference marsh used Ihe site tor roosting and theedges of rhe marsh tor preening and res ing. No corn-parahle high tide roosting site was available ln rheconstructed marsh; he artificial islands were used byonly a few egrets, Most birds preferred the sn!aII avail-able patches of picklcweed during high tide. Publicaccess trails at the Hayward site were «onslderablycloser o wildlife areas than trails in the bay marsh,and no buffer vegetation was presen Josselyn et al.1987k As a consequence, few birds remained in theHayward Regional Shoreline Marsh whet! visitorswere present in the park.

In their 1987 report, Josselyn ct al. concluded I.hat"project objectives should not focus on any one habi- ar type... as an indication of success." At this writ-ing, the site is heavily invaded by !I! «!vi nu <r rernifl<!r«,an invasive Atlantic Coast species M. Josselyn, per-sonal communica ion, 1994!, and no new studies areheing done.

and ln some detail over the past 14 years.The area covered by pickteweed increased

quickly, PlanLs spread from the occasional clump in197f! to provide an average of 40% cover an!ong the1979 survey si es. Phyllis Faber began the monitor-ing work with a survey Of vegetation, soil salinity,.!nd Iiabitat quality. Dne condition of the Bay Con-servat i<in and De VelOprnent COrnrn!SSiOn permit Waat<i e»<!hfish a sell-sustaining cordgrass habita forw,nerf'owl and shor 'birds. In 1<! l. S years al'tcr thedikes «crc ir!ili,<II< hr<.ii«hed, ridaI Iu«s uel'<' in'iid-<'qu,'ll<.' fol 1CC <rig his g<ial Tli <' apl!er pari uf lhem;lish was n i feveli!pi»g he natllral sinuous chan-»«Is o the li!v,er para I iahiigan and Bryar!t ct al.I 994!.!!uhscquen ly, new channels werc created onrh ' p<.!i<1! ', er uf the i!larsh tO in«re<<so tidal a«rinn.The fi!lhiw ing year cordgras< had increased o more har! 38 !, I I ! Pl:!n s I'rom hc 1979 count ol f60 ! Williams et al. 19 I k The cordgrass is now moretha» k9 m tall. and c<iver continues to advance

By year I ! ol the project, additional species of

pl nits b<'" ill ti> ilpp<"I>. Itet<< i.'<'n I'!<! ' iii,l ! <! ! t I t,eiida»geIOI'l>I I Cl'>ppei rails 'i�<1 I ! <pe<'ie i>ff>sh wel I>set < ed»1 b<'>III Ihe co>is I i etc<'I »id I'I,'i i>-ra! iii;irvh<s, !hseii.i ><»is iit ho h»>;Irshes»iiti<,;iietlieV ill'e Ilsn us<'d iis lish nuixei! si es.

ln 1<!<J ~, W II II:It>is;Itid Axs<>CI'I'ieS n<>teil h;it,i till�!Vpniductive hiihita ;It Morat Miirsl> is l»i»teil li< ill<r.'} e of sedn»ent <tioll l Ilie tii'lal >>i'll sll pl,i»>v [t'll .'Isung>cst liat ii n>ay iak« tati yeiirv '<ir lie s>t< to >e.>ch

<'quilihn<»» t>o<><l» in;md Willi;ii»s I'!'! '!. Naturaldei clop>ll<.'�l Of Cli ili>leis ni the tipper pan Ot' thei»ar h is sh>v . lb» h>gh elc<iition iif the niar'h mayprccliiiie ihe ih:vehipi»en <>t sloiighs h<hitgan andIt! 1 iiii <'t;il. I <!<f4!. Thc Chang>»I' top<>griiphy Of the 'Iiiiiiiiels Is .'I prohle»i, P<a>ls th,'It 'Itli" Iel lish t<ir ltid-iiig:ind breed»>g iuu less ribe luncti<>r» i>l he I'<inner.

llurnb«ldt liny '%litigation 'Marsh

Lesson: lf functions of a destroyed hahitat are to be replaced "in kind." hydrologic characteristics of themitigation site must he equivalent.

Fnglish sole accoiiri ed fiii S !'< of he total o tertrawl c;itch in all iireas ciitiibined,6S "< in the channel<id j;iceiit »el�!, 44<7e in thechannel iuljacen ui the control nta> sh Fureka Slough!,lilt<I 5'r< in;ireas near the ini igatiiin inarsh tFreshwa-ier Sl<iugh!.

Chamherlain;ind It;Ir»hart �99.1! concluded,"f veil though a successful inter ida! salt tnarsh wasestablished, it did not;ulequately mitigate he losthabifa from c<instruction ol' the Woodley island Ma-rin:i." 1 hc rcs orati<in created an upper estuarine habi-t<it that prininlrtfy benefited juvenile and eutyhahnefishes Chamberlain and Hamhatt 1991!. 1 did notpriivide the suh idal and inter idal habitat k>st at theniarina site. Felgrass fla s and piddock clams wereno replaced. The h;ihitat a Wo<>dley Island Marinawas a reliitiVely Stiible, subtidal inarine en1baymen ,beneficial tpot in>t species !.

Iii additi <in. C hamherlaiti and Barnhart cOneluded liat the choice <if reference sites limi ed equitablecomparisons hect<use hydrologic and physicochemi-cal characteristics were inarkedly dissimilar. They rec-ommended tha more acreage than tha lost should beprovided because ol' the time required o establish afully I'unctional system and because <>f the uncertaintyof attaining equal habitat quality. they I'urther recom-mended that data on both the construe ion and resto-rati<in si es sh<>uld be provided before any alterationof ei hcr site was done.

Salmon River Estuary

Lesson: Subsidence of diked wetlands can shiw restoration.

ha former high sal marsh had been diked for pastur-age. Restoration began with partial dike breaching in197!I. No channel excavation or slope c<intouring wasdone, and na ive plant species were not transplantedinto the area. Res oration depended solely on he natu-ral establishment of salt-marsh vegetation.

Located along the north-cen ral Oregon C<rcs . heSalmon River estuary is pan <if he Cascade HeadScenic-Research Area established hy the U.S. Con-gress in 1974. The long-range goal of the U.S. Fores Service was to re urn the area to a system free fromthe influences of humans. Before res oration. the 21

The c<ins ructiiin <>f Woodley lsl;ir>il ~%1;ui>i;i ii>Ifu»th<>ldt ltay, C alilomia see I ig. I. I a!. req<iirc<l hain>itigii io» he pr<iviileil to repl,iCC I»s shiireline,subiidal, anil intertidiil li;ibi a v. E <>nst>»etio» i>t liemarina also ilestfoyeileelgrl<ss beds '»ld a pi>pillatii»iof piildiick clairis. Thc .S-h.< site chi>sen l<>r niitigii-tio>1 Is Ii>c,'<ted >. ki» et>st of thc lll'Il »1I' Fresh«;<ter Sli>ugh Channe!. Since ! !�>, ihefiirmer saiilt marsh hail beei> used pr»iiarily iis pasture:md sec<>ndai'ily 'is a wawlttt II pond, Rest<>ri<1 h>li <if thcsite consis «l <>t' ilike bre;u:hing In Dccc»ib< r ! <Jgt!.

Tii de en>tine v he lier lie restotcd n>.irsh providedI'u»ctfons equivalent to those iil' he destroyed hahi-ta s. ii 14-n>onth viu<'Iy wils <1<'»Ie I ha>iiherlaii> iIndBiin>han 1991! He weeplex werc collected fr<>ni thc acent channels,in the riiarin;i, in he restored rut>i m:irsli. <ind in anundixturbed IreterenCe! marsh, Sai»pling I»ethods irt-c! uded I ixed «hanncl neLs, ichthyi>plank i>» net. OrtertraWI, heach sei»es, aiiil drup trapS.

Not surprisingly. vari;i i<»is occurred between thecons ruc cd site, the con r<il site. and th«res»ired si e.Variation in salini y was grea er and mean salinity sig-nificantly lower in the water adjacent to the mitiga-tion niarsh. Likewise, sa linit ies fluctuated niore in themarshe» than in he adjacent channels, particularly inthe mi iga ion marsh, a shallow-wa er retention area Chamberlain and Bamhart 1993!.

AE<> <It ATIQN EFFoBTs <JN THE PACIFIC CC>AST 37

t'<ig-Le-Hi- Te Wetland 'System

Lesson: Development <if wetland functions is not always a siinple progression.

Monitoring took place over 10 years, beginningin 1978. Mi chell �9811 compiled the first data be-fore dike removal and analyzed wetland attributes overthe next 2 years. Characteristics of vegetation, siteelevations, salinity, soil texture and organic con ent,sedimentation, «rid erosion were studied. In 1988,Frenkel and Morlan �990! surveyed the site, ad<lingto and summarizing the body of data.

intrusion of salt water initially eliminated the es-tablished pasture cover. Two yean al'ter breaching.salt marsh vegeiation began to appear on he mostlybare site. As upland pasture communities were re-placed by salt marsh communities, the diversity ofplant species generally diniiiiished. Pickleweed andsaltgrass became established on he seaward area;sedges C«r<cr Iv<r<;hyef! doinin«ted the inland edge.These three species dominated he restored marsh hy1984 and by 1988 accounted for more han 70% ofthe vegetative cover Frenkel «nd Morlan 1991!. Overthe 10-year restoration peri<xi, elevation of' he creekbanks generally increased, and the creeks becatnenarrower and deeper, Primary productivity in Ihe re-stored area was nearly double the productivity of theundiked control and pasture areas and is thought iobe typical of a developing ecosystem IFrenkel andMorlan 1991!.

Although data v, ere <i<it recorded for numbers andspecies. juvenile tish, birds, and mainmals were ob-served using Ihe restored esiuary 11 years after dike

The Ciog-Le-Hi-Te Wetland System was constructedby he Port ot Tacom«on he upper part of the PuyallupRiver «s mitigation f<ir tilling an existing wetland habi-tat. Construction began in 1986 with a breach in theriver dike, connecting, the 3.9-ha site Io an existingestuary. and subsequent tr«nsplanting» of sedge,

The U S. Army Corps of Engineers permit requiredmonitoring nver a S-year period �986 � 1990!. Sys-tematic sampling of sedimentation, vegetation. fish,birds. infauna, and epibenthic zooplankton was donein 1987 and 1990 Shreffler e al, 1990, Thorn et al.199i!. By the second year of sampling, the popula-tions of infauna and epibenthic zooplankton had ap-peared o stabilize, and no further collection was done Thorn et al, 1991!.

A primary objective of the project as establishedby resource agencies was to allocate 50% of the newwetlands for use by juvenile salmon. The remaininghabitat areas were designed to support waterfowl,shorebirds, raptors, and small maminals Shreffler etal. 1990!. Although use by salmo~ appears to have

reinoval. Tliis would indicaie tli<ii a iiiiiur«lly t'unc-tioning, lov salt iii;<rsh ecosystcin is developing. Toassess its progrcs» accurately is diliiculi. Even theexi~ting undihcd marshcs used as reference wetlandshave been indirectly disturbed by human ac ivities.

Ai the time <il' breaching, the restoration area hadsubsided <dx<u 3S cm bcc;<use of hu<iy«ricy 1<isa, corn-paction, and organic soil <ixid«tion Frenkel andMorlan 1991!. In the first decade. accretion of sedi-ment had increased the clev«ti<ins S-7 cm in the low-est areas and 3 � 4 cm in he higher areas. To achievethe goals of the I,; S. Forest Service may take fivedecades or morc Frenkel and Mtirlan 1990!. Changesin wetland charac eris ics continue. Long- erm moni- oring will pr<>vide da n riecess«ry to determinewhether some iniervention is appropriate and desir-able.

Frenkel«nd Morlan �990! have observed that heobjective of the t!,S. F<ircs Service to return theSalmon River Estuary to its n« ural condiiion, freefrotn the influences of humans, was nr< y p«r <r<fjv at-tained, because of the diflicuh> in «ssessing pristineconditions. Re-creation of entire communities ol' or-

ganisms. plants and animals included. hatare closelymtxleled on those iha occur naturally Jordan et al.1988! seems tn be a realistic general goal for restora- i<>n. In these terins, restoration of this site on the northshore of the Salmon River can he c<msidered success-ful Frcnkel and Morlan 1990!.

increased since 1987, he goal of y I'ir. use may belimited hy the increasing sedimentatio<i in the chan-nels, The 1990 increase in he number~ of salmonid

caught reflects one particularly large catch and maynot represent a long-term trend Thorn et al. 1991!The 1990 inonitoring showed that nine species of fishoccupied the tidal channels. This represented a slightdecrease in the number of species present in the pre-vious 2 years but was coinparable to nuinbers foundduring the 1986-1987 surveys.

The number of bird species in the estuary was 118in 1990. This is a 50% increase in the number presentin 1986. As many as 500 individual birds were countedusing the site on a particular day. Some data suggestthat he system has reached its carrying capacity; thenumber of species «pproxirnaiely 36! present duringthe summer months h«s remained stable over themonitoring period Thorn et al. 1991!.

The density of sedges increased at a dram«bc ratebetween 1988 and 1990. The initially transplanted48,000 ~hoots had increased to more than 420,000

39RESTORATION EFFORTS QN THE PACIFIC COAST

Pacific Coast Terininals Salt Marish Compensation

Lessons: L Coarse soil, low supplies of nitrogen, and grazing nay slow growth of transplanted plants.2. Trial plots may be useful when restoration techniques are limited.3. Historic dumping may itnpair the potential for restoration.

pl<inta hy l'!'!ll. Duruig this s,iiiie pcrio<l. a <en c<,vcrdecreased from a hich of l6,6'~i iii 1987 lo 7,4',I< iiil99 !. Changes in sh<iot density a id ifie amouni <ilab<iveground «nd bclo«ground bi»inass were used oes imate thc rale of dcv<.l<ipinen <if the ransplaiitedsedge Th<i<n ei al. 199 l !. A plaiil survey iii Ihe si<n<cyear lis ed >7 plan species I'ouiid in I or several ofthc i0 hahita ca cg<iries. Of liese. ~6 species h.ivccolonized na .urally,

One problem in evaluating the success»f 'og-Le-Hi-Te is the lack of coinparable surveys and theabsence»f giaul nearby reference si cs, S <mens ad andThorn l996! observed hai the lack of specilici y inlhe pert'ormance criteria will haunt interpretation ol'the projcc 's success forever. It is evident from thecontinuing changes in the hydr<<logy and species com-position ol' the marsh that considera hie 1 ine is requiredto establish equilihnuin in we land restorations. Scour-ing and deposition ot sediment are increasing in thetidal channels, and use by juvenile salmon may di-

C<msirucli»n <il' a nev, storage tank facility al thePacitic Coast Terminals in British Columbia wasmitiga ed by lhe development of a salt narsh habi-tat. The project was required by thc na ional fishhah~tat policy o thc Canadian Depanmen of Fish-eries and Oceans Williams 1993!. Salt marsh res-toration is relatively ncv in this area. The resu11s ola 1-year moni oring program suggeste<l hat exis -ing strategies for estuarine rcst<ira nin may be inef-fec ivc I'or habita of his type Williams 1993!.

lntenidal sediment dredged from the construc-tion site was used as fill for the new marsh. The sitewas graded in May l993. Atter placeinent of lhedredged materials, the area was O.S m higher than inl 991. Although not previously used as a dorniiiantspecies for transp}anting, saltw nit G aux mar<rima!was harvested from approved sites aiul transplamedas cores during May 1 993 Williains 1993!.

onitoring was done at the mudflat, the com-pensation marsh, and an adjacent salt marsh as con-trol!. Data were collected on soil density. pH andelectrical conductivity. Analysis of fertility i< eludedmeasurements of total carbon and nitrogen and ofamounts of available nitrate and arninonia. Periodicobservations of growth were recorded, and pho o-graphs were takeo,

Results showed significant differences betweenthe control and the constructed marshcs, In the con-

niinish, As a large rc«iurce, diminished use bv salrn»nmav he seen as a tailurc to fulfill the erma»f the

mi i gati»n a <eemeii . hideed, because this is the onlyemergent marsh habitat now available o migratingjuvenile s<ilnion in the Puyallup River estuary Shre ffier el al. 199 !!. so<ne intervention may be nec-essary to increase the suhtidal habitat. O her probleins<iota<i a< c tlic iiccumulat ion and removal of rubbish, he seasonal ex rcmcs lha can threalen emerging eco-systents, and thc dangers of ex rapola ing linear mod-els oldevelopnien to «e land systcins.

T' he period <il ni<aii uring specified in the origi-nal per nil has elapsed. Hov ever, the Fisheries Re-search lnstitu1e continued sampling by using Gog-Le-Ifi-Te as a U.S. Army Corps of Engineers WaterwaysExperiment Station demon st rationsite. Simenstad andThorn �996! have presented an overview of the sitedevelopinent, with 7 years of data on physiography,vegelation, and animal use and .special aneiniOn tOthe issue of performance criteria.

s rucled marsh, soils v ere much coarser, soil pH wasmore acidic, and elec rical conductivity was lov erthan in the control marsh or inudflat Williams !993!.Salt wort and pickle weed were the predominant colo-nizing species. However. a the end of the first grow-ing season. plain growth was so poor hat c<iveragewas a<it determine<j. One factor limiting initial plantgrowth was hc high carbon-lo-nitrOgen ra iO in theconstructed marsh, Successful early establishmentof transpl ants was severely aftccled by intense graz-iiig by Canadian geese. According to G. Williams personal communication!, the site was hisi»ricallyused as a du<iiping area f<ir b<ith sawdust and sulfur.Ahhough he layer of sawdust v, as removed, chunLsof sulfur reinain»n the si e. CJeneration of acids fro nthe oxidatioii of sultides may be the cause of poorplan growth. Nevertheless. ho h .sal wort andpickleweed were considered the inost appropriatespecies for transplan a ion Williams l 993!.

Subscquenl recominendations tor monitoringemphasized the need to establish trial plots in whicha variety ot' remedial measures arc used. S»me sug-gestions for impr<ivemenl included creation of tidalchannels. soil amendments for greater nu rient avail-ability, and revised harvesting and plan ing sched-ules. The need io develop an ecological perspectiveto habitat compensation v as proposed as a futureobjective Williams l993!.

CHAPTER 3

Problems inRestoring Wetlands

4Q TIDAL WETLAND RESTORATION

3.1 PROBLEMS DURING iMPLEMENTATION

The baiic prohlems in reitoring iir creut iiig ciiaital we -landi concern hydrology, iuhitrate, arid hiota. r!f these,hydriilogic priiblemi are docui»eilted nioi1 <if en. part lvbecauie they are easier o ice and partly because theeff'ccts on !he enlire iystem are drainatic.

3.1.1 Hydrology artd TopographyProviding both pr<iper»dai flushing arut topogr:lphy iicritical t<i rcitoriiii<in ot c<iai al we hiidi. Marih plan sare extremely ieiiiitivC tO tile degree iif itagnatiiin Ian-OX!al and iahni y Ot iOil. EVen a I I!-em rl»itakC in Cl-evatinn ean prevent the deiire<tniarih pl;inti lriim g!'ow-ing well, it thc hydriiperiiid t'rcqueilcy an<i durati<in <il'iidal inundiuiiin! <tit'1'<ri fr<im what ii »ceded. Iii ad<ti-

iiin 1 <level<ip, thuireducing pl i»t gr<iv th: whcreai in areai with too s r<mga cuircn, er<iii On i!!ay «Ccur, thus rCmOVing .ra»iplantedmarih ipeciei. Either improper planning nr nlii akei !ninlplci»t'i! ing reit<!ra iiin plani can rciult in uniuitablehydr<iltigv. Iyur!J!g ciini ruc»iin, the <iver- or under-ex-C<iviiili'lil <il iilii.'ll Jd.'ll tie' la<'id illci Cilil Cre ite 1»'JI»i pniti-Iei»i, he<",<<lie ipe<'lei '<1!e ii! i<.'I!iJIIVe IO i»le!<it<!pi<-graphic di I'I'< rc 1! cci.

L neXPe<' ed eve<1 i Il'ii Ciiui<. i«it!i!ieiliii iiiii tii!<tuilcspeeicd ch;ir!gei ill i<'I'll Jli:Ceii d ii! !Jig C<iniii'ii<'I!i!i'Iota iite Call J<'iult i11 en!it<i<1 arid <teti<ii!JJO». Jleiiller tifwhich a idi Ihe eitabliilirnent iit traiiipl<ii!ted ice<1;iii<m,A ciimni<!n prohlenl iiccuri in diked wietl;indi th;ii h,iv!:been rem«veil fr<im idiil t'luihing I'iu many yeari; th<.iubi rate iuhsidei. and eleva i<a!i .!re lowered. Si<»ptvhreaChing the dihei d<!Ci niii rCi are the We lan< i tO theirpredike c<indition, hoiicvcr. '1 he .ialt i»arih iit Oregon'iSalmiin Riier liiiuary is an example, Because iifsubsidence. the reito red iite i» inoit ly tow'-n!arsh h.'lbi-tat that mai take a Century Or rnnre 1<1 accr< te enOugliiedimenii to bring the t<ipography hack to its predihed

conditiiin Frenket and Miirlan, l99 !; cf. Salnuin River

Estuary c<lie stlidi' iil chap1ef !.Too much accreti<in cauiei pr<>hlerlii v'here Iidal

channc li are cut into ieinit idal or nontidal areai I ct. Warm

Springi Marih case study in chap er 2k Such excavatedareas <! ten sedinleni in, especially t<ir iites dredgeddeeper than the downstream channel tha feeds them.Sedimentation rates have increased following devel<ip-lnen aCtivitiei ln the waterihed. Onul I 19f�! repnrted a4! J< decrease in Ihe low-tide volume of M»gu Lag<i<inafter t cods transporled icdimcnti to the lago<in niouth.Ai iedirnents fill intertidal channels, tidal flows beconleiluggiih, and sand huildi up acr<iii he ocean inlet.

Corrective meaiurei arc available for areas ot' sub-

sidence 1 c.g., dredge spoils may provide iui able fit I ! an<1areai of accretion e.g., Jnaintenance dredging after theI;ici!, hul theie »measures prolong the time the ecosyitei» ii diirup ed a!id increaie the likelihood of iilvasionhy exoiiC ipeciei Cf. iections 2.3.3 a!!d !Ak Hence. it iihei to plan with the knowledge that topography andhydrology may change during tie devel<ipment of anecosystem, lt i» eisential to predict he proceiiei thatwill control water ialini y. water flow, deposition of sedi-men i, and eroiion. When iedimentation events ca!! bcpredicted, it may he poiiible to cutnpensate hy«verexcavating channeli that are likely to accrete sedi-ineilii P. Willi a ms, Philip Williams Associates, personalCiiinmunie,'ltl«11 I.

Perh,lpi the ii!«iiOh V iiius hydrOIOgiC Or OpngraphiCerriir ii h;lt c<!nitrucie<t nlarihei rarely "1<ink like i!<i u-ral n!iir.h i Th c< n Jru 'I 'd riiai h' ailway' lack theciiililih.'x !Je %<irki ot irililll tidal <.reeki.;!<id tiroad, fla marih plaini are cornpreiied <ir;ibiei!t < cf. Muzzi Marshcaie i udy in chapter i. Bulldozers ofteil create;1 c<illa e of habitat typei that rarely w<iuld ahi!t one an<!therf<ir example, steep-iide<t iilandi and deep, itraight chan-Jleli cf. Hayvi<trd Re iorial Shoreline Marsh case stud>in chapter 2!. Iiolaie<t habitati can pose ieri<ius prob-lenis f'<Jr biota that need iranii iiiili bctiieen hahitats lcf,iectioni 2.4 and T.3k We recomn!end using natural

PROE LEMS IN RESTOR NG WETLANDS

riiarvltei iii »1<!deli of the 1<ipographic crimp ex itv;indhiibital ciiniiecli<ini neck!cd bv niitive biota.

3.1.2 Substratea'lhe quality <il the iuhitrate and v <<ter often difleri fiirnatural '<iid corri i'<ic ed v'etlitiidi. Th<.' itilli i'ii e O'I cx<",i-viitcd ii ei rii:iy bccomc acid when cxpoicd 1n can in;idvertently uncovertoxic r»a eriali it' the f<irtner v'etland liad been uied as alandfill. Reitoration iitei may alio he downitreai» ofcontaminated v,aleri. Iri urban areai, marihei can accu-mulate trash, v, hich imotheri vegetation. Such locationiwill n<it iupport high-quality wetlandi,

Soil texture, Natural rnarih .iiiili are line- exlured,whereas thoic of construe ed niarihei are often coarse,hccauie the iile of the constructed man lt often c<miiitsof dredge ipoil dep<iiili or upland lill. In chapter 5, wed»cuis the shortcoming» ol sandy soils in restored lowerand upper intertidal i»arshei. The supply and recyclingof nutrienti «re impaired when c<iaric-grained iedirrientiare uied t<i griiw salt marsh vegetation Langii et al.1991!. Water absorption, impoundment, and retention areimpaired when sandy i<iiii are uied initcad of clay-richrnarih iedimcnti. Salinity regimes may also be affectedif the substra1e draini too readily lcf. iectiiin 5.'2.4!.

Amount of organic rnatter. Organic iedirnenti area basic lcaturc ofiialural we landi. It has been suggestedthat organic mat1er influences nearly every aspect of thefunctioning <it wetland ecosyi emi: by changing sedi-men porosity and water-h<ilding capacity, by inf!uenc-ing nutrient dynamics, hy altering the growth rates andno rien content ot' pluri i cf. Pacilic Coait TerrninaliSal Marih ompensation case itudy!. and by influenc-ing the speciei compoiiti<m and abundance of inverte-hratei aii<iciated with the scdimenti, The micnibes,pl mti. and animals in turn affect the rate ol accumula-tion of organic mat er in wetland iediinents. For mostwetlands, the developmeiil of organic sedirnenii iiccursover periodi that are closer to centuriei or millennia thanto years or decades. In three regions of the UnitedSlatei � N<irth Carolina Craft et al. 19116, 19118!, Texa~ Lindau and li<iiincr 19III I. and Southern California Langii et al. 1991! � comparisons indicated that the lev-els of organic matter and ni rogen in sedinients werclower in constructed and restored v,etlands than in thenatural reference wetlands I Table 3.1!.

Soils of all of thc constructed marshes had leis thanhalf the organic matter of natural marshes. L<iw levels oforganic matter may impair microbial activities nitrogenfixation, nutrient recyc ling, iulfate reduction!. They mayalso influence faunal density and c<impoiition, no onlythrough trophic linkagei but also by altering the com-pactness of sedimeo s and he ability of burrowing faunalo colonize the sediment cf. section 5.1!.

3 $.3 BiotaSeveral hindi of biological poiblerni have been recog-nired in a temp i t<i reitore Pacilic Coait niarihei. Theieinclude! imi ;iti<ini <iri lraniplanl;it ion. diiconnccted hah<-tati. inVaiiOnS Of eX les have ied to ieveral recommen<latioriiITable 3.2!. Because of the ihortage of rialural marshcs,iourcei of tran splanti for rc itoralion sites are scarce, Re-nioval ot plants from a region'i wetland reierves is no advisable. Hence, plants ihould be salvaged whenevervegetation ii being destroyed, so that hey can be trani-planled. Il may he neCeiiary lO build interim nurSerieito hold plants until reiloration sites are available. In theSan Diego Ray pro!ect, an inter idal nuriery wai built in191�. planted with ialvaged cordgrass, and allowed togr<iw l<ir about 4 years. Mere coni1ruction ol nurieriesii not enough. however. The c<trdgrass nursery v, ai ac-cidentally destroyed in 1990, v hen the adjacent area wasbeing bulid<ired to expand habitat for cordgrass marih.Another ialvage effort I'ailcd when blocks of high-marshvegetation were .ilockpiled and irrigated <vi h freih wa-ter for several yeari. LIpland weedi invaded ai the salin-ily of the ioil declined, reducing, the quality of the soilfOr resloratiOn effOrta. FOr iuCceiiful ia!Vaging Of COaS alvegetation and.iod blocks. a long-term plan and a rnain-tenance program for the nurieriei are required.

Perhaps the most common problem with transplan-1ation in Southern Califoinia is hypersaline soils. Theaverage salt content of lower marsh ioils of naturalmarshes is more than 40 ppt, and only a ftood or a rnaj<irdischarge trorn a reiervoir can lower the salinitiei lo sea-water or hracki.ih levels, Marshes that have been dikedbecome even more saline, and some ot the highest ia-linities develop in dredge spoil~. Al San Diego Ray, theaverage ialt coricentration of newiy excavated dredgespoils was 80ppt on initial tidal influence: valuei droppedto C5 ppt in the tirst 2 m<>nlhs despite lack of rainfall andrunoff, H<iwever, levels did not decline significantly overthe next 4 months. Transplantation of cordgrass may needto be delayed until tidal IIushing lowers salt concentra-tions to at least 50 � 60 ppt.

42 TIDAL WETLAND RESTOAATION

Table 3.1. Organic Carbon and ota i rogedT t I N t gen in Natural and Constructed Marshes in Three Regionsof the United States Total Nitrogen

Organic Carbon '1o! {mg/kg dry weight}

ConstructedNatural Constructed NaturalMarsh Age yr}Location

95227-5880. 3-1. 1 0. 1Tex as

322-92410-15 0.6-8. 6 0. 6-1. 8 364-1,680

870-9602. 0-2. 5 0. 1-1. 1 1, 740-2,270California

IVofe/ Based on data from Lindau and Hossner 1981 Texas!, Craft et al. 1988 North Carolina!. and Langis et al.1991 California!. Marsh Age = years between marsh construction and sampling,

Table 3.2. ConalderaTions In Establishing Tidal Marsh Vegetation in Southern California

~ Soil salinities should be lowered initially to facilitate halophyte establishment.~ An excavated site may need several months for tidal flows to leach accumulated salts and lower substrate salinity.~ Fall and winter are good times to transplant salt marsh vascular plants.~ Prolonged periods of low salinity will stimulate exotic plant invasions.~ Most halophytes will not colonize readily e.g., cordgrass, Zedler 1986! and will need to be seeded or planted.~ Most salt marsh plants will establish from seeds and from cuttings that are rooted in a greenhouse.o Seed germination is reduced and delayed by high s alinit ice, as well as low moisture.~ Cordgrass Sparfina fol/osa! seeds need to be ripened before planting; germination rates are highest when seeds

are stored in the refrigerator in fresh water for 2-3 months and then germinated in fresh water~ Each halophyte has a narrow range of tidal conditions that favor iis growth; it is best to plant species at the

elevation where it thrives in the nearest natura! marsh.~ Cordgrass grows well in shallowtubs kiddy pools! and can be propagated readily fromrooted cuttings. However,

permits are essential for collecting plants.~ Genetic diversity of transplants cloned from one or a few culms will be low; the consequences of low genetic

diversity are not clear, but a diversily of starter plants including plants grown from seed! is recommended forvegetative propagation efforts, while taking care not to contaminate local gene pools.

~ Local stock shouldbe used in all marsh restoration projects, using growers who can guarantee the source of theirmaterials.

~ A grower should be contracted to provide materials at least a year in advance of site availability.~ Pick leweed Sa//corn/a virginica! outcompetes cordgrass f or nitrogen Covin and Zedler 1988!; hence. it should not

be planted where cordgrass is planned.

~ Pick leweed is a good invader if there is a seed source, but planting will speed canopy coverage.~ Glasswort SaAcornia subfermina//s! grows slowly from seed but should be grown in tali pots to accommodate deep

roots

~ Shoregrass ASnanfhoch/oe/ifforafis! grows from cuttings and seeds and has established well at Marisma deNacion San Oiego Bay!.

~ Salt marsh bird's beak Cordy/anfhus man'fimus ssp. mar/fimus! has very specific planting requirements section2.4!. and special permils are needed for this endangered species.

~ Pilot plantings are recommended along transects perpendicular to shore; plant species at the elevation whereinitial survival and growth are best.

~ Fertilize plantings experimentally to determine what limits growth and spread.~ Use irngation for upper-marsh sites, especially where s ubstrates are coarse.~ Monitor plantings for insect damage and small mammal herbivory; September to November is a likely time for small

mammal grazing, as the marsh soil is less often wet and there is less forage in the upland.

Nof e. Based on Zedler. 1984.

PROBE EMS IN RESTORING WETLANDS 43

t!taco»»ected habitats. Whc» hathi mls are c<in-s ruc ed as isl«nds, the lack of terre< ri;<! corri<hirs canred<tee Or eliminaIC n<»ural m<ivenien S Ol SOnie anima!s.even lyiilg iiiscc s. pi'ed'<tory' heel!ex <<erc ii<i initi;illypre cn a S,'n! Dicg<i B<iy s dredge . p<111 i Jan<i ChulaVis a Wildlife Reserve!, and their <Ihscncc see» s 1<i bercsp<insiblc f<ir hc ex cnsive al ;icks hy sc;ilc insec1s <inCOrdurass r;insplan S Cl. seCtiOn <.I!. Where hee lesabound i» all c<irdgrass ol' natural 1»arshes and on the»lain!<1<id Surr<iuiiding the B;<V. Sea!C i»SCC Ou breakx niayhc kept in check hy predation. Isla»ds of high-»iarsh habi-tat at a»ii1her San Dieg<i Bay res <ira io» s»e see t ig.2.s! provided suitable habitat lor rein roduclion of,i» en-dangered plan . hc salt marsh bird's beak cf. section2,4!. H<iwcvcr. only 2t!<y«if the plan s were pollinateil B, Fnik, PERL, pers<inal co<»rnunica ion !. Without a seedhank and with insut'fiCien pOllina iOn 1O pr<iduee <ieWseeds, annu il species canno pcrs is . Bcc p<illin<itors need1»arsh-upland trans ion habita for their ground nests;uidf<ir al crna ive sources <if nec1ar that ced the bees whenbird's beak is no in flov er.

I'.'xotic species. Too <iften exotic spec ies � tnith a»i-n!at and plant � heconie cs ablished ii Constructedrnarshes icf, tlayward Regional Shorchne Marsh casestudy in chapter 2, and section 1,4!, Other than the knowl-edge thai exo ic species take up space and reduce thepotential f<ir the development ol'native specie~. we haveli»le infornia ion on h<iw hese aliens change '<lod webs

:ind wetland unct iiini»g. A Japanese mussel M<is«<li.s <i.<enf<<iusiu! invaded lhe c<instructed marsh a San DiegoBay in large numbers bu was only rarely present in thc<ia ural reference «e la»d Scatolini and Zedler 1<!<J6!.Because many pac! tic Coax es uaries already have largenun!hers of introduced invertebra es, resean:hers and o h-ers are c<incer»ed that m<iving transp!an COres frOm Onewetland o ano her e.g., Saii FranCisco Bay Io ElkhornSlough! v ill bring unwanted species along with the de-sirable plants M. Silberstein. Elkhorn Slough NationalEstuarine Research Reserve, per a>nal communication!.

Vuod chain support functions. The few data avail-able indicate tha considerably lov,cr abundances of in-vertebrates or vastly differen spec ies of invertebrates arepresent in constructcdmar. hes than in reference wetlands.Scatolini and Zedler �996! examined the epibenth<is oi'San Diego Bay cordgrass marshes and found similarspecies hut greatly reduced densities in the 4-year-oldcons ructcd site. Cammen l 1976a, 1976b! reported sig-nificant differences in the infauna of constructed wet-lands along coastal North Carolina. At a 1-year-old marsh,the doininant taxa were insect larvae, whereas polycha-etes were dominant in the natural wet!and. Total densi-Iies a»d calculated secondary production also were mark-edly lower than in the»a ural system. Similar observa-ti<ins were made at a 2-year-old site. Sacco et al �994!revisi ed the 2-year-old site when it was approximatety15 years old and found a 10-fold increase in densities

ind a high similar»y v»h lhe ii! t;iuna <il iia ural niarshes.Siudies <i!an upland si c hat w<is graded <i suppor Sti<<IS<ilu <<fr<'f!irf 1<iI <I fo<i<1<t I!i<it Ihe coils» acted sile ha<tI'~'wer nema odes. ostr,ic<xlss h,irpac ic<»ds, and <iligocha-e es Iha<1»'»'ui"il »u<rS!les 1 M<iV 1<!! 9. S'ie<'o 1<!g9. MOV;<<id I.ev»i 1 9<! 1 !

Species c<imp<isiti<in <Ries i»» a! w;<ys bec<imc»i<nosimilar through time. Mov !'!g9! reported a divergenceill Co<lip»sit<<!<1 <ive« I -Veai pen<i<t !le Wce» <1 CO»-structed inarsh;md iiriother <»;»sh recciviog Ihe s;<niesource <sa er as1hc created site. S <ceo !9X9! evaluated

he composition, dens itV.:Ind trophic s ructure of infaunain coax al North Carol<<in inarshes 1 � 17 ye<irs after theirciinstruction Although variable. Ihe data sh<i<s ed that thesiX COnstruC ed marshes had si<iiilar f.iunal C<irnpo»entxand lrophic groupings dcpos» lccders, suspension feed-ers, and carnivores! hut that dcnsitics werc uniformlylower ha» in na ural marshes.

A study of the food chain at 11juana Es uary icl'. sec-tion 6.3! v'as co due ed 111 199: � 94 1o provide he er:<dViee fOr prOjeCIS tha seek I<i inipr<ive or Create habi 'itfor es ui<ri»e fislies. Fist»upp<irt is a m;i!or require»!ent<if SCVeral pr<ipOSCd riii iga i<»1 pr<ijeets ii1 SOuthern Cali-fOrnia e.g., San Diegui <i t.ag<ion and Ha i< oil<is LagOOn,seC ion 7.2!. 'the degree O whiCh lish ar< suPP<irted byalgae that grow in channels «iid by vascular pla» s oralgae tha grow in the salt marsh has s<gni icanl impt ca-tions for mi igation proJects, lf the fish depend on thcmarsh 1'or food, then mitigation credi is suitahte for largeIreas <il intertidal niarsh adJacent to sub idal channels.

3.2 SALINITV PROBLEMS

Southern Calif<irnia es uaries are s<»all and so!a ed, a»dannual rainfall events I tiniing ol rai<il'all. s orm inten-sity, and streamtlow! are «Il highly variahle cf. section1.1!. The norm is hard lo de <»e. bu the region is con-sidered semiarid; average annual raintall is ah<i» 3 ! cm.Sr»all watershcds arc typical of mos of he regio»'scoastal s reams; hence, intlows of tresh wa er iiccur i<ipulses, Under natural condi1ions. s reains roost likely hadminimal flow in summer. During the cool season No-vember � March!, which is the rain> sea~on, estuarinewaters bec<irne ephemerally hrackish, although coastalspring~ may have created si»all areas ol'more persistentbrackish conditions.

3.2.1 Reductions in Sa/inityVirtually all municipal v,'a er in Sou hen! California isimparted a»d stored in reservoirs. N<irthem Californiaand the Colorado River are the maJor supp!iers. The re-lease of water as stree or irrigation runoff or its dis-charge as treated eff!ue» alter he hydrologic regimeof coastal rivers and dov nstream estuarie~, There is of-ten too much fresh wafer. And, because estuarine inle s

TIDAL WETLAND RESTORAT QN

in Southeni Calif'<irnia h;ivc a tcnilericy I<> close, tidal«s»ng may h' iiilernipted f<ir 41<illihx Oi VCa S at atinie lCf. sectiiiii '2, 1 at!d Los perlaxqui Os LagOon Casestudy in chapter 2!. There is often t<>o little sali v «ter tosustain lhe inarine character ol thc coastal wetlands. Dur-ing the n<>nt id<it i» erv<ils trcsh w;<ter can accumulate,and several bi<ili>gical changes c.ui <iccur. Current re-search on the eft'cuts <>f re<}ucli<>iis ill sr tinily s inad-e<tuate fnr Set trig speelt ic' Iiilii s ii� lie releasC' <1'I wastewater. H<iwever, h» stt>d cs c}carly show the aced tiic<insider the dctriniental e ffcc s <if deliberate discharge<if trcsh water tn is iiiiiving intuit<I, wlicrc it is i»<irc expen-sive o discharge w<istes «i i>cciin ou tiills, I bus. it hasbeen pnipi>scd th;it the vc<» cw;<ter tr<im fllesc' iiewlydev<.li>ped inland areas hc ire;itcd aiid discharged oCo<>stat !itl'<.u itis I<'li reuse ii'I iirigati<>11 <liiwiisirc;in1thr<iughout the l<>ng <fry s«<is<xi 'I'hc Calitonln<Rcgi<iii'ilWale Qual> y f- <iiilr<>l B<iar<t Saii t!!egn Reg>nnat Wa-ter Quali y Cow w< inld reach coax al wet laiids.bu discharge <>t wastewater w<iuld exceed irrigationclenlands, iit least ii92 lhe wet seiisi>fi.

Uiitrews iiiti> lie United StatesIr<ini the City <if' I'i juana. B'ij;1 Califi>min. which includesinativ neighbor}1<><>ds [hul do<i<'lt have si.wc'r lines, Flowsiif was ewa er wcf<'. ub<1ut 49 milli<>n liters/day of rawsewage o Ti tuana River and Tijuana Es nary from about198fi <1 1991 Sea>nails I'Ntl. /<dier ct al. 1992k Bo hlong-rc nt arid cataslr<>ph>c assaults on the coastal habi ats have producc<J a lliglil V st>essed eeosys enl During1993, ca astrophtc se v 'age spills in excess of 64 mi}lionliters/day caused t>ea<.hes in <he area to he closed forrn<ire than 22 l days C. Rtcks, San l3icgo AssociationOt C>Overntnents SAtstDA<J. PcrsOnal COmmuniCationkTijuana wastewater» have liig" c<incenlrations of p<>11 u an s, because <if h<>th liiw per capita water cc'Insuinpti<>n and lcwei' coiltrols on contaminants fn!m indiistfy,ln fat11991. the raw sewage was diverted to San Diego's

sev age reatnicnt pl;uit during <itf hours. Ilowever, thec<illccti!i' systeiii ovc'1 fliiws dul ing raiii cvcnts. Even con-struction ot the ncv border sewage treatinent plant dueto opcratc in 1997! v.'ill ni> prevent win er flows of raw

sewage.An occasion>nal source of excess fresh water is reser-

v<iir drav downs. After major f1 <ioding occurs. water mustsoi<11ctiincs lie rele;ised tron> reservoirs to sustain flOOdproteciion. Fl Capitan Dain discharged water for severalmonths after f1<i<>ds in January and February of 1980.Flows ot' fresh w a er n ihe San Dieg<i River estuary con-tinued through hc summer Zedter and Beare 1986!. In1993, Rodriguez Dam discharged t'resh water well afterIhe 12 days <it c<mtinual rain thai o«cuncd in carly Janu-ary ot' ha year.

O her intl<iws of' fresh water occur where agricul-tural irrigation and street drains I'unncl tlows froin irri-ga cd tields or lav ns into nearby coastal ivetlands.Finally. spilts I'ronl storm drains or sewer sys erns occa-sionally lilt wetland channels, especially during heavyraintall and runotf, Tijuana Estuary has had continualinllows of raw sewage trom the opsrreani metropolis ofTijuana Seamans 1988. Zedlere al 1992!. Since 1993,these sewage flows have been collected and diverted toSan Diego's treatnient plant, s<i that flows to the estuaryare now restricted to times of floods that excec<l the ca-pacity of the interceptnr.

3.2,2 Increased Freshwater InflowUnder natural conditions, many wetlands in SouthernCalifi>mia would receive little fresh water except dur-ing streanillow pulses in wiiiter after the occasional rain.'I here would be an ex cnsive period of little or no flowduring the long dry season. Changing thc hydrology fromintermittent freshwater pulses e.g., f'our to tive majorflov events in 15 years! to continuous flows reduces hesaliiiity ot the estuarine waters and sediments. and thebio a respond when inajor shift» occur t'rom saline tobrackish or fresh conditions,

Prolonged periods ot Iow saliniry convert salt marshhabitat to brackish marsh dominated by catlaits I vphaspp.! and bulrushes IS><'<rp<<s spp.: Zedler and Beare 1986,Beare and Zcdter 1987!. Prolonged freshwater in fluencecan also eliminate niarine fish and inver ebrates cf sec-tion 2.11, Fish and inver ebra es, which are well adaptedto seawater, are killed during natural floods, but popula-tions can reestablish thcmselvcs after marine waters againdominate the estuary. Where streamflov s persist becauseof discharges, he natural channelassemblages are el imi-naled.

At Tijuana Estuary, fish and macroinverrehrate spe-cies have been less diverse since was cwater inflows be-came substantial beginning about 1986!, The numbersof individuals collected in our monitoring programs havedropped by an order of magnitude, and large clams arerare. Young-of-the-year are present, so we know that lar-

PROBLEMS IN RESTORlhIG WETLANDS 45

v<W;Ire;ii a<I,IbIC I<»CI IC, hu Ihi:y rarely surs iVC t<i re.pr<iduic X<irdtiy;Iii<1 i',cdlcr 199! !.

lii Or<i<'.I' I<i de el I'IIII'Ii' O'I'I<' hi< a Induct l<nl Iii sidinit V

;iluiie I rind Il<ii ci!iiulininant s in the raw sewage I can elimi-

nate species, various experiments have bccri doric withtish anal Iitvertehr<I es. 1 hC COnClus<On Is that l<iw saliii-ity c<iusci m<irtali y. especially <if rii<illuscs Isiordby,Raclk<iwski.;<<Id z'.e<tler, unpublished data!. Morc de-taile<f exp<.riinenis o» Calil'ornia hiilibu showed thatgrov th <it juvenile I'ish is reduced when salini y is lowand tha lie et tects arc gre.' test on thc sr»a lest Individu-;ils R;iczkowski ! <!921. Dry-v cather discharge of tresh<rater is thus considered a signiticant factor, above andbeyond thc pniblenas caused bv ma crials carried byIntl<iwirig water.

Thc effects ot' waviewa er <tischarge can he reducedby i<ale;ising water it> pulses rather thol c<intuluously�edlcr et al. 1994k arith' experiiiierits on both t'ish andmolluscs sh<iw«d reduced damage w hcn exposure to low-salinity water wits via pulscs Nordby, Baczkov ski, andZedfer, uiipublished diita!. We have dnne mesOCOSm eX-perinten s to shov that wastewater v:etlarids could bec<instructcd t<i retain water and discharge it in pulsercWe hypothesized ha such wetlands would liave an im-pr<ived ability to reniove riutrients front he wa er col-umn, much as East Coax freshwater tidal wetlands sup-port mnre iiutrient uptake and higher plant produc ivitythan we lands wi hniore constant water levels. Twice-a-day iinp<iulldfnen arid d<schai'ge Ilo oiiiy Irltpr'oved thecapabilit! <il wet!and mes<icosrns t<i remove nutrients butalso enha»ccd uptake of heavy metals Busnardo et al.1992. S Inicriipe et al. 199 !. Thus, wc think ihai ihc prob-lem ol rcducti<ul in saliriity call bc decreased by usirlgpulsed-disch,irgc wetlands upstream of the estuary seesectnin 3.2.4 I. However. this is only a means of reducingadverse effects, no a way ol eliminatirig them.

3.2.3 Eutrophication and ContamirtantsL'rban runoff and sewage spills introduce a variety ofunwanted materials to coastal bodies of water, Patho-geni are of parncular concen»n urban areas, and fre-quent pr<ihlems arise in coastal areas, such as San DiegoC<iunty. 1!uring 1992, thc ocean ou fall for the sewagetreannent plant at Poin l.orna City of San Diego! spilledmore han 171 million liters/day of treated effluent intoshallow ocean waters. The spill continued f<ir severalweeks. 'f'he ihreatof contaminat.i<m by pathogens led tothe cincture of all nearby shores, including those in SanDiego Ray. The region's favorite recreati<nial beacheswere closed. aiid ourism was no doubt al'fected. San Elij<iLagoon appears to have a leaking sewer pipe under it,w hie h allows p a hog en s to enter the water column Dodge1994, Matkovits 1 994k When the mouth of the lagoon isdredged open for tidat restoration. nearby beaches arecontaminated and must be closed to the public R.Gersberg, Graduate Sch<iol <if Public Health, San Diego

Sta c l 'nivcrs<ty. Pcrs<iii'il c<inlrttunicat ion I. Su<<age tlow sfrom tlie f. ity ot Tijua»ii present the larges health threatto Southern California bcachei. Fecal coliforms havebeelt nronit<rre<tat Tijuirrla Es uary during recent years.ariel duriiig the ra»iy seasOri levels are apprOX in ately thes« lit<. 'Is Il'I<iso <it I 'iw scv'age Crersbelg e al. 1994!. Ad-jacent beaches «rc usuallv closed during ramfall events.

Nutrients, detergenti, oils, pes icidev. fertilizers.heavy mcials, aiul oiher IOXiC intr erratS are alSO presen in urban runoft'. Orice coiitarnin<mts reach the dov nstreamcs uary, they may become concentrated near the inf iowaor dilirred and carr ied to the <iccan. At times and in places,the tlows are irilp<lundcd hy sand bars that block tidalflow. Contarninants adhere to sedimen s and accumulate.These become hot sp<its 1'<ir contaniinants Trindade 1 988.Gersberg et al. 9�9! arid hi<rh biol<igical demand N<irdby I9t tt, 19hq!

Heavy nictals,irc abundant in was cwater enteringTijuana Fstuary. S<iinples ol' surfaCe water have Con ainedmean levels of 69 ppb of cadmium. 5S ppb ofchromium.2ft 1 ppb of nickel, and 321 ppb of lead Gersberg et al.I~N9I Es uarine sediments act as a sink for heavy met-als. c<intaining up t<i I 7 ppm ol' cadmium, 25 ppm ofchroniium, 14 ppin of Iiickel. aiid 59 pph of lead. Con-centrations of heavv nierals arc particularly high wheresewage waters are impounded Trindade 191 Hh Heavymetals and other toxic mu erials enter we land f<i<rd chainsand concentra c in organiims, but the extent of he con-taniinatian is not Clear. NO studies <if bi<il<igieaf COnCen-tration in S<iu horn California s coa!<till wetlands havebeen published, although some sampling of the tissues<if various organisnis has been done S, Goodhred, LI.S.Fish and Wildhfe Service, personal communication!.

Eutr<iphication additioris <if riutrients and associatedresponses! as a resul of wastewater discharge is onlygenerally known. Mexican sewage contains more than2.5 mg/L of nitrogen and more than 10mg/L of phospho-rus. We know that productivity of vascular plant~ inTijuana Estuary is nitrogen limited Covin and 7+dier1988! and that macroafgal hhairns are stimulated bywastewater intl<iw s Fong e al. 1987. 199ll. Salt marshvegetation is more productive in years of major t'loods. ac<msequence of better growth under he combined influ-ence of lowered soil salinity and increased nitrogen avail-ability Zedler, l<irdby. and Kus 199'21.

3.2.4 RecornrnendationsYear-round recycling ol municipal water would elimi-nate the problein of excess freshwater flows to coastalwetland i Greater reuse of imported water would «lsoreduCe diverSIOn Of water trOm the San FranCiSCO Baydelta, where f'reshwater int'iowa are needed to sus ain the

biota. Similar concerns exist for the Owens Valley andthe Colorado River angel et al 1995!.

Total reeycting. Treated wastewu er can he used toirrigate crops, but Southern California does not have suf-

ficient agriculture near the sites of wastewater produc-tion. Hence, f<>r reuse to solve the problein, most likelywe would need o use realed wastewater for drinkingand other dornesiic purposes, When fresh water is broughtin from Col<irad<>, it includes treaied was ev ater that hasbeen discharged in other state~. 1 is made potable byfurther purit ication in wa er treatrnenl plan s. However.drinking ot' was cwater effluent hat has been producedand treated within Calif<irnia is permitted only if lhe ef-fluent is first passed through a groundw >ter aquifer toreduce the potenlial lor virus ransmission, IVf< ire researchis needed on the satety und accep abilily of total recy-cling, and helter methods are needed to remove patho-gens arid ensure the safe y ol reused water.

Using excess fresh water to create wetland habi-tat. Treated wastewater could be used to construct a>idmain ail> lreshwa er wetlands that wi>uld subsidize habi-tat for estuarine birds while inarsh vegetalion and soilsimprove v ater quali y eniering the esiuaries. Bulrushwetlands have high capacity f<>r nilr<>gen rein<ival. wi hnl<ire ha E 9 !9< reduction of total nitrogen al hydraulicresidence times ol s � f> days Gersberg et al. 1984,Busnardo et al. 1992!. Constructed we lands are alsocapable of removing both bacterial and viral indicatorsof pollution with a removal efficiency <if nearly 99.9 lnfor poliovirus vaccine strain; Gersberg et al. 1<!87!,Sinicrope et al. f f 992! reported the removal of subslan-lial aniounls ol the heavy metals present in was ewa er.A recent study of lhe ale ol' trace nte al s in a COri slructcdwetland iii H;iywurd. Califoniia. f<iund <umilur resul sfor the removal of copper and zinc Gregg and Horne19931, However. concenlratiiins ol nickel and lead in-Creased o g,rcater than those present in inf fuen was c-water and are hough to be the resuh of aerial deposi-tion. Reduc>ng the concentralions of these metals at thetrealment plan or u the source may be necessary 1 Greggand H<irne 1993!.

Bec;nise augi»ented u>flows are detrimental to South-em C<ilitorili:i s es uaries, ciinslrilcled wellarids wouldneed <>he enguieered I<> discharge treated was cwater inpulses. A brief influ>«if fresh ~ater would i»innnizeadverse effecis ie.g., reductio i in salinily! on the es u-ary. Recco expenments showed that rates of removal ofheavy iiletals and nitr<igen were highest during ahydr<iperiod of' twice-da< ly irnpoundrnen and discharge Busnardo el al, 1 992, Sinicrope e al. I 992!. With hisregiinen. denitrihcat ion rates >nay be enhanced, leadingto removal of additional nitrogen from the system. Also.problems wiih mosquitoes might be fewer because ofthe more rapidly flowing water.

The po ent ial for using cons ruc ed wetlands lo man-age wastewater in Southern California needs o be ex-plored. Pulsing the discharge of treated wastewater couldreduce the impact of lhe reduction in salinity and im-prove the qua i y of effluent entenng the coastal we -lands. Hov ever. total recycling has greater poten ial for

eliminating the problei» of loo inuch fresh waterPacific c<>as al v<e lands require a region;<I; pf,r9 r< i<le h

arch imd inanagcmen sec ion 4-'h ln S ur q~.~California he anion<1 <[idliiiiiiig <ifdischarges nuit fmanaged lo maintain native vegeiaiiOn and ass<,~,s. Cienl I'Ormanagera IO wOrry <i<iiy,lf

i<< Ihe loss of fish'i<id shellfisli habila . I cause e<ldallvor - IPoredspecies are often jeopardized by loss of we larlds <tr> .ageinent models cannot be derived I'rom data <>il re@eV «v<!swhere phints and animal» are <nore olerani of firuek;s.isiswa <'.r.

Controlling contaminants. There are nVrurtlsfor consis enl monitoring of contaminants in cons a< 1 tv<idies of water. Monitoring <il pathogerla is iil em>it «t tefforts do not include all we lands. Beaches «sc.<!swimming and surfing are the usual arge s, eveii t it<i«, hpeople also swim an<,l w;ide in lagoons. A great <tern aminanls and to provide remedial i<in;>Isites that are already contaminated.

3.3 PROBLEMS OF URBAN WETLANDS

Urban wetlands are iinpor anl to city dwellers. who @<titsan occasional glimpse <if' native habitat, They are el>s<'essential to native species ha depend on specific ~'<1-land habitats. Jn Southern California, endangered spe-ciess compete for space with a variety of urban uses. +etcas highway v idenmg, dredging f' or recrea ional b<» ing, and filling for housing and commercial uses. T»ereis not enough coastal land to f'ulfill the nation's pc>fteYof"no net loss" ol both wetlandhabitat and funct«ir>'">

and still allow unrestricted urban grow h.Even when urban wetlands are sel a~ide as reserves-

habi at degradation continues. The hydrologic «fee'are discussed in sec ion 3.1 Locally iinportan effe~include trampling and associated dis urhances ea<tscby an ever-growing human population that enjovs <-'Vspace.

3.3.1 Visitors

The proximi y of an adiniring public raises the iss<~how many visitors wetlands can tolerate, espec>+1 I v

when visitors bririg their pets. Allowing visitors 1<perience v'elland habilats helps the public appre+;~le

PROBLEMS IN RESTORING WETIANDS 47

nesting or feeding activities is unknown. Others Jualiusand H irsch 1979! have shown that birds' heart rates in-crease before flight, indicating that animals can bestressed before their behavior so indicates.

Table 3.3. Effects of Human Disturbance on Wetland Birds

No. of DaysObserved

Flight

Min. Max.

Behavior

Min.

Change

Max.S~ea ie s 4 4 3 5 5 3 6 4 4 4 2 6 514 8 1143 24 3726 20 2115 6 829 15 2030 14 1817 5 11

0 55 6227 17 2324 14 21

6 5 517 8 1517 8 11

124026112027

17 024'i5 6 8 8

American cootAmerican widgeonCinnamon tealEared grebeSnowy egretCommon egretGreen heronGreat blue heronAmerican avocetBlack-necked stiltShort-billed dowitcherKilldeerthfillet t

Note: Data taken by Pam Beare PERL! indicate distances she could approach before birds changed their behaviorand before they flew. For some species, flight occurred before a behavioral change was noted. Numbers of observa-tions were small and varied by species. Distances estimated by eye; minimum and maximum distances rounded tothe nearest m.

and support wetlands. Proponents of free access by visi-tors argue that people can safely approach birds in urbanwetlands. However, no data are available that indicatewhether thc birds that continue to use urban wetlandsare the same ones that would be there without urbaniza-

tion or whether the birds that remain are just the speciesand individuals that can tolerate human disturbance cf.Hayward Regional Shoreline Marsh case study in chap-ter 2!. We can never know how sensitive the natural popu-lations are, because they are no longer natural,

The immediate effects of great number of visitorsinclude disturbances caused by noise and movements,trampling of vegetation, and predation by cats and dogs,The presence of humans in and around coastai wetlandsis disruptive to birds Powell 1993!. Experiments at PERLshowed that shorebirds have a range of sensitivities to aperson walking near their feeding site Table '3.3!. Thegreat blue heron is the most skittish, whereas coots arerelatively tame. In order to plan for the highestbiodiversity, the needs of the most sensitive species mustbe accommodated. A 60-m buffer would be reasonableto keep visitors from disturbing the great blue heron.Currently, the California Coastai Commission requires a30-m buffer, and that can be narrowed if the applicantshows that a broader buffer is not required, A 7.5-m bufferwas approved for developments around Los CerritosWetlands in the Los Angeles area.

Powell I 993! showed that Belding's Savannah spar-rows Ammodramux sandv ichenxix heldingi! are dis-turbed by the presence of visitors at about 30 m duringthe birds' mobile, nonterritorial phase. However. whenthey are defending their nesting territories, the birds canbe approached closer, Whether this impairs the bird' s

3.3.2 TramplingThe effects of trampling are significant on a local scale,especially at the upper margin of the salt marsh, Severalhigh-marsh vascular plant species have narrow elevationranges where tidal inundation is infrequent Atrip/exii atsoni h glasswort, salt marsh bird's beak!. Because thisupper-marsh band is seldom muddy, it is a choice loca-tion for informal walking trails. Repeated tramplingeliminates the more sensitive species first e,g., A.wutsonii, glasswort! leaving the tougher plants shoregrass, saltgrass! to dominate until all vegetation isdenuded. One entire pai.ch of the endangered sall. marshbird's beak was obliterated at Tijuana Estuary by unau-thorized foot traffic; the nightly migration of undocu-mented workers from Mexico to the Umted States via

the Tijuana estuary was responsible. The entire estuaryhas fewer than ] S patches of bird's beak. so this loss wassubstantial, When surveillance of migrants was intensi-fied, trampling was greatly reduced, and the bird's beakpatch reestablished itself.

The effects of trampling can be far-reac.hing. AtTijuana Estuary, both vehicle and foot traffic have nearlyeliminated the vegetation that fon~erly stabilized the bar-rier dune. Without vegetation, sand i» blown and washedinland, filling estuary channels and reducing the tidalprism along with sediments from the watershed. At AguaHedionda Lagoon, the excavation of tidal basins as partof a mitigation project Kei-Cal 1985! has inadvertently

"Mo<t<!<ed from i edler f992.

48 TIDAL W ET I.AND RESTORATION

increased abuie <if a<f]accnt »a ural salt rnarihei by rid-eri on off-r<iad vehicles. ln thii case. the mitigation sitewas not excavated low enough to be I'ully tidal; hence, itis a dry salt pan that invites vehicle lratfic, which mnveifrom the ialt pan o lhe adjacent pickleweed rnarihei whenthe marshes are not too muddy. Substantial damage o he natural vegetation hai occurred. This mitigationproject not <inly did not a<.hievc iti habitat goal freplace-men ot' a pickleweed marsh!. il also catalyzed degrada- ion of the nearby natural mar. h.Vehicle traffic denudeithe vegetation. reduces habitat quality, and compacts theioii. Revegetation ii ditTic oil in hard soil, and diiking toloosen the soils can enable colonization by exotic spe-cies of plan i ct. iec ion 3,4!,

Denudation of dune vegetation «t Tijuana Estuary didnot produce a crisis until a natural iea i orm washed theiand into the tidal chanrieli. Chiiure of' ihe cituary <ic-currcd a year later. in 19�4, when rainf'ill and streamflowwere too l<iw o puih iedimenti thr<iugh he mouth of'lheestuary. An I -in<in h nontidal droughi then <tee<mated

p<ipulation «if cordgraii, invertebratei. and, eventually.the light-footed clapper rail Zedler. Nordby, and Kus1992k The sea itorm comp<iunded thc effects <if increasediedimentation and tranipling. Small-scale dredging waineceisary lo remove icdirncn i «nd restore tidal flushingin the short term: a major dredging and reit<<ra i<m pn!-gram ii needed to eniure con inual tidal flows in the longterm.

3.3.3 Lack of Buffersln S<iuthcrn Cali fnmi<i, there arc no native trees to;ict ainatural buff'eri between et<as at wetlaitdi and «dlacentuplan<t developinents. There is no easy way to icree» wet-hmdi fr<im lighti, n<>isc, and m<ilion. becauie fencing iic<liltV;Ift<l;i<eai 'litt;ice it tri Wetlandi afe OO saline foinioil lail wo<aly plants. F ven if these <neasures were cost-ctfectivc. i would be inadviiahle o develop up t<i lheex renie high tide line. Such dcve lopmcnti would not ontybe inundated during itorm iwelli. hut «iso he doomed loinund;it<iin in future decadei ai icu levels con inue io rise.

There aread<ti ional reaioni o provide but'fer zonesbetween wctl:in<ti and urban developinent. Broad ex-

pa<isei ot open ipace are available in natural wetlandi,iind the transition zone between wetland and upland habi-tali .iupporti hc we land biota,

Although it may not be obviou~ except on extremehigh tides, he transition zone be ween wetland and up-land provides high-tide refuges for mobile ipeciei thatd<i not like to remain in deep water, A San Quintin Bay,.S't0 km south of San Diego, the broad transition-zone

habitat ii uied by wetland birds ai a resting site duringhigh tides. We land iniecti move to high ground whenthe tidei inundate the marsh plan i. From the terrestrialside. sni all nlammals. lizards, and snakes burrow or hidein the upland and lhe traniition z<ine and move into he

wethindat t<i« tide. The itnportarice <it inch iv<.'ilaiid-uplarid linkagci hai n<ii hccn quantified. hut wc i<iipectit is great on the baiii of two rei <iraliiin prohlcr» i in SailDiego Bay liecti<in 2.3I.

The endangered ialt m<irih bird i beak requires morethan the wetland habitat v here it gr<nvi. 1 hii high-i»arshipeciei «ppeari to rely <in buffer zonei irt,it lc;iit twoways. Ai an annual, it riiuil iet ice<I in ni<ii years tosustain tile p<ipulalion. aiid pollinatioii ii ciicntial Par-ioni19941. The plant'ipollinatori are terrestrial iiiiecti.that ii. iolitary bcci that nest in s<iil above high tides. 1 alio requirei irnall oper> ipacei I'<!r icedlingi t<i becomeestablished and grow through ihe marsh canopy, Liirgeopen areai arc uniui<ahle. because the plant is ahemiparasite that grov .i beit in asi<iciatiiiri wilt< vari<iush<iit plan i. The diiturbancei that provide sm ill patches<il'open ipace may depend <in the actioni of imall mam-nlali ox it<id Zcdler 1986k Uilf <!I'tunatcly, little int<lr-mati<in ii available on the kinil;ind amount of habitatneceisary to maintain the appropri ate popula i oni of bur-rowing rnamrnali.

3.3.4 RecommendationsSouthern California's urban wetlaiidi are ex ens ivc ly andintensivcf> disturbed. Visitors disturb v etland biota andtrample habitat. Tra<npling can eliminale ipeciei withnarrow elevation ranges. The effects of trampling ol'dunevege ati<in can be magnified by na ural sea itonni andriiing iea level. Recom<nendationi include the f<ill<iw-

I'I g ~ Viiitori ih<iutd be kept on pathi that are clearlymarked and 1<icated in places that prevent adverseeffects on ieniitive ipeciei,

~ Viiitori' activities noise, lights. peti! ihould beregulatc<l to minimize advcrie effects <in wildlife,

~ Buffers are needed to distance wetlandi from de-

vcloptnenti. They are alio needed t<i tune ion ashigh-tide ref'ugei an<lai habitat t'<ir uplarid ipecicitha play important roles in the adjacent wetlandtpollinatori. mammals that open sntatf pa ches inthe high-marsh canopy!.

~ Further research is needed o tietp iet he widths ofhuffers and determine allov able activities withinbutTer zones. ufo if such information ii available,it makes sense to use the broadest buffer zones that

can be justified. Data on great blue herons iuggeitthat 60 m ii appr<ipriate

3.4 PROBLEMS WITH INVASfVE EXOTICPLANTS'

Invasive exotic plant» threaten coastal ialt marshei. b<ithhy invading adjacent mudffats «nd by displacing nativevegetation Several situations promote their invasion, in-cluding enhanced diipen al, iuhitrate diiturhancc, and

PROBLEMS IN RESTORING WETLANDS 49

hydr<ilo 'ic i»<idit i«itions »speci«! tv re<I»»cd soil s<ilin-ity!. A c<iri>iiioii featiire is th<ii shor -term alterations inenvironnicntal c<indi iona it>i i.'ite Inn<'-ter>«gem»n strategies should hcrct'otic focus <!n pr<.'vi.'nti<!n,

Reciirds ot the arriv<tl a>id early spread ot exoticplants «re rare. iind some species introduce<t by hum;itisare accept»t sec<» I;iir tndistinguish spe< ies carried by humans t'ror» tliose tha a>rived vi;i the feet, tbathcrs, or guts <it other well-knovvndispersal agents n<itably birds", V<viun-Smith «nd S ttes! 994!. he distinction does enipltasire the fact that hu-m<»is have hart un innnlinatc influence on the worM. Ifwe knew how propagules arrived and wli<it coiiditiorlsallowed their spread. we r»ight be able to predict spreadand suggest control>»ensures. Indirect evidence ot'whenexotic species tirst becanic abundant c;in be obtainedtrorn pollen profiles in wc lamt sediments Mudie andByrne l9! t! t. Adobe bricks inctude seeds ol' weeds thatv ere present at the time of the bricks' production, Her-bar>um c<>lieu i<>ns an< species maps may indicate timesand species that were historicalty rare and places wherethe species later hccamc abundant, and ncw floras indi-cate expansions of exotic species in recent years Rejmdnek und Randall l 994!.

3.4.1 Adverse EffectsEx<nic plants that can grnw lower in the intertidal ronethan n<t ive p!ant» can reduce he area of mudflat avail-able tn sh<ircbirds and sonic invertebrates <>f economicinterest. A species with grcatcr tnlerance to inundationmay naturalize rapidly wtlere ther» arc n<> «>mpetitnrstn slow its establishment. !n Willap;I Bay, Washingion,the invas inn <>f.'>P«>ain<> airer>ri f!r>rn int<> rnudflats threat-ens a major oyster industry. Invasion nl' intertidal tiara intire« Britain by nonnattve cordgrasses section 3.4.J!has reduced feeding habiia l<ir native wading birds.

When ex<itic plants invade vegetated areas, they maydisplace native specie~. In Southern California, the in-vasinn of the h<ew Zea!and mangrove, A<ircenni<> n>r>-rin<r, irlto thc habitat i!t native cnrdgrass Sp<rr in<< f<>l«>sa!is considered de rimcntal to both plants and birds ct.sectinn 1,4.3!. A few mangroves v,'ere planted in Mis-sinn Buy. San Diego; their escape prompted concern tha the trees would displace cordgrass, which is the preferrednesting habitat and nesting material of the light-footedctapper rail, and that the trees would also provide roost-ing places for raptors, which readily prey <in rail chicks P. Jorgensen, Califnmia Departmentof Parks and Rec-reation, personal communica inn!. An active eradicationpr<>grain f'ollowed, with annual visit» to puB out man-grove seedlings by hand.

The indirect effects of changes in vegetation are notwell known. Although many wetland animals may lackspecies-specific requirements for plant canopies nr nest-ing ma erials, insects are n<ited I' or their tight dependen-

cies oil sill>'Ic !toit spec iev. Soirle illsectv <<re l loll te<t tnindividual families <ir cncra ot' plants: <ithers «r» re-s ric e<t to a sing!c species or t<> a single lite siag« e.g.,tl<iwcrs or seeds! <if a host plant. These same dependen-cies are present uniting thc inscc inhabitants <if c<iastalwet!;univ, vet wethin<t insect cnr»niunities have receivedlittle a tentioii C.. !s!a< ano. L.'S. Fish and Wil<t tile Ser-vic<.', !lerr«iii<11 I:<illlliiurli<",<t»in</ e>ali!, appearsti«N<r! tor larval lb<ding.

Changes in vegeta ion are no «!ways consideredentirely detrimental. Recent and r<ipid changes in veg-e ation are taking place along the estuaries of the Swanand Canning rivers near Pcrth, Western Australia �ed!eri.'t al. !%7: cf. X.AA!. 7'v'f>f><< <>in< nr<<f<». a cattail, is rap-idly expanding into native salt niarsh. where it replacesjt<»< ><,< ir<n<.<iii and other native species Pen ! <!!�!. LikeCalifornia, the weste»i coast nf Australia has few coast«!v et!ands, attd thc displ«cemcn of salt marsh vegetationis viewed as a mariagenient pr<>bier». However, becausethe native purple sv amp hcn P<>rf>f>y> i<> f><>rf>f>yri<>! useshabitat dnniinated by T>! >I«< species. he managerial atti-tude is thai sornc Tv!>i><r expansinn is acceptable R,Atkins. Waterways C<irtirnission. Perth, persona! cnm-munica ion!. Likewise in Fngtand's Pnnle Harbour,exo ic cor<tgrass is v.ilucd for its ability tn ci>ntrol shore-line em<ion Gray I9!!C! The managerial opinion is thata tittle is good, whereas a lot is not A. Gray, Institute ofTerrestrial Ecnlogy, personal cnmniunicatii>ri!.

Manag»rs are g»»»rally morc concerned about lossesof aninial habitat than about changes in composition perse, Threats tuit type aiic thc exception Salt marsh bird' sbeak is an endangered plant species that iiccurs at thehindward edge ol intertidal salt marsh»s in SouthernCalifornia section .3!, where its habitat is often dis-turbed, an<t v eedy species sometimes invade. nuttergo!dfietds L<rsihe><i<r gf<rf>r<r <>! is a rare plant in South-ern California Ferreri ! 9!!.'>!. At the remnant popu!ationin Los Penasquitos Lagoon, it occurs in close associa-tinn with an exo ic annual Cr>r«frr < s»<»t<>pif<>!id< J.Boland, PERL, personal communicationh Invasion ofFlorida's brackish wet!ands by cajeput trees !ref<rien« r<! ni, section 4.3! has prompted a cnst ty con-tr<>l pr<>gram aimed at retaining the marsh character ofthe vegetation. These twn conccms merged when cajeputtrees werc deliberately introduced to Tijuana Fstuaryadjacent to habi at <iccupicd by salt marsh bird s beak.'I'ree removal was required after the invasivc nature ofthe exotic plant was publicized. and concerns I' or thenative vegetation were voiced. Da<»age cnntrol is imari-ably an expensive response io pn<ir planning.

In at least onc case, an exotic has become the over-whelming dominant plam of a major coastal wetland.

50 TIDAL WETLAND RESTDHAT ON

The discovery� Spichcr and 3osselyn 19hs! that the donii-nant cordgraii r'n Humboldt Bay is an exotic from Chile .<ilr<rrrinu de>rsrif<rruf rather than the California native .Spurri rrrz f irik r iu > hici prom pted concern thar this invadermight d iiplace the native ciirdgraii over a hr<>ader geo-graphic iirea M. Josselyn. San I'ranciico State Urriver->iity. and P. Kelley, California Departme»t of Fish «ndClam e, personal coniniunic;i i<>n!.

3.4.2 Conditions Promoting InvasionThe c<iriditi<mi that «iliiw invaiion by exotic wetlandplants cari hc iletcrmincd hy c<iniidering what prevents he eitahliihnicnt <it these plants in he leas diiturhedwetlands Dispersal, di.iturhance, emporary relief' frontcovin!niiiei'Ital it! eii, 'uid pi<!l<iriged chiirigei iri the i.'ii-v iron>>le>Et iill ci!n r'Iliiitc ti'I Irivaihiiis,

Ifhahitati ale suitable fiir 'ipt'c>l.'i Il'lat are ilo prese it,then the iinly limiting f'act»r ii thc;iv;iilahility»fpropagulei. [X:liberate iir accideii a I intr<xfuct ion <>I" ieedior planti te,g., planting <if inangri>vei in Mission Bay!will then enable cstahliihinent. If the ahi<itic environ-riien i» iuitahle, hu native inhabitants deter establiih-ment {e.g.. hruugh ihading <if icedlingi or consumptiori<il ieedi!, then iome dii urha»cc otic environment ii oo itreiiful le.g.,hyperialine! ti>r iced germination and iriirial es ahlish-nient, their a sllolt-ten>> I educ ton in stressful condit <or'Iile.g., 'i pioloilged flood 1 Ii>iiv i liow invaiion I e g., inva-sion and periiitence <if 1'q>ir<r <i<nirinkernr> in San Dieg<iRiver IVIarsh: cl. iection I.4.4h If the ahiotic environ-irreri ii uniuitahle. heri;i pcriisterrt change in environ->non :il c<inditii»ii may enable invaii<in ie,g., <nvaiionsilf kl<rrr<' i <'I'i >J>lsition <il'.iediinenri from up-itr«aiii criiiioii at Loi P«>ras<luitos Lagixin; cf. iec ion: .4.41

If twre limiting fa<.'Iori are removed, inva-iiiui n><ivci fri>ii> thc poiiiihlc to the probahle. Such wuini<iit likely the caie fiir the early invaderc whoie seedstl"ivelcd ti'I 1'lew 1<urdi 1rti, nioved up newly con-itructcd naviga ion channeli, or encoun ered estuarieswhere hydrology wai heing altered hy changing patternsof land u.ie upstream in the watershed. Multiple factorsappear lo he reiponsible for the rapid advance of T.rrrierrluii < intm nev housing developments is dii-charged through newly cut channels across the adjacential marsh. Neither lowered salinity nor substrate distur-bance ii sufficient for he eitablishment of Tpfrh<r seed-lirigi, hut the comb>nation enaNei ieediingi o becomeestablished in the drainage channels; thereafter, Tvphuinvadei the native marsh hy vegetative expansion of adultplants Zedler, Paling. and IvicComh 1990!

A iluliihcr < if i rrv,is iiiiii i i> crit<ital vs c laiidi have fx errdescribed rcc«»tly, and althou li hc ipc«ific < vents thatcaused the eituhliih»ieni trid ipre;iil <il' rhe exotic plantsare undocumerrred, rhe prohablc cauiei cari he infbrredfrom the aii<!cia i<i<i with certain cliarigei, S<n»e inva-sions af'ter deliberate or accidciital introductioni <if ipc-cics, a<uric after Ill al<!r liy<fn!logic «Iiaiigci. rind o hersare con»non w hcrcvcr iuhitratcs are diirupted. Erich i E-vaiion may have multiple c iuici.

3.4.3 Deliberate or Accidente I IntroductionInvaiii>r> iil exotic species may he citlier acciden al ordeliberate. 1 hc «laisical it<>ry of invaiiori ol exotic plari species in ialt marihes is that <>f .>par rirr<r rrr»iui< rr<liir5frurrrrr<r ungii i u in angl and. In the 19th cert tory,,'>'pujari >rauilerni fir>ra appeared in Eurupc, where marsh graSSeS arevalued for control of ih<ireline i'.roc>i!li and niarih huild-

>ng through accretion ol icdiment, It hybridized with thenative <iir<rr rirru rruir rlirvru to form an inf'ertile hybrid,,'>'ir<rr lrnu rri>< i<sr rirlii, first noteuhling to f<>nii an aggressiveand fertile polypl<>id, which wai noted in 189' and laternamed .Sp<rrvinu unkir< u. Wrth its i»creased vigor andthe potential t'or iced dispersal, the nese speciei spreadrapidlyi ln Piiofe Hartx>ur, in southern England, it wast"tri recorded around 1880; by 1924 it had formed a marihof more thar> 775 ha and raised the top<>graphy by morethan a meter in many areas. The plan » at Poole Harboursupplied ieedi and propagulei t<>r a <s ide range of iiteiaround rrea Britain, the F.uropearr continent, Australia,New leal;md, Ni>rth Anierica, and Chin; > Barnci 1977,Cr'ray 191 ~L On the Pacitic Coait. it ii currently knownfront Pugct Sound and Sari Franciico Bay ISpichcr artdJ<>ice lyn 19115!.

The primary management concern ii the loss ofmudflat habitat f<ir shorebird I ceding t Cross-Cuitard andMoser I9III !. As Long and Mason �983, p. 137! put it,"Spur i>ra overgrowi the mudflats and renders them use-leii f<>r feeding by waderi, who ali<> dislike roosting inthe tussocky growth." Herhicides have been useray 1985!.

<ifr <trit na speciei are present ty of corrcern in Califor-nia. Spurt>'nn <i<'rrsifkrru isa caeipi ose hunch! graii thatdominates the intertidal salt marsh of Humboldt Bay andhas begun to invade San Francisco Bay. Vntil reccnrly, itwas thought ro be an eco ypic variant of the nativeS>p<rrri nu firlirrc<r. However, Spicher and Josselyn �98S!showed that it is a Chilean species, probably carriesa and outcornpetes the na-tive pickleweed ISuli<orrri<r iirginr<a! IJosselyn andBuchholz 19'!. Its spread in San Francisco Bay has been

PROBLEhAS IN RESTORING WETLANOS

summarized by Jossefvn and Buchholz as f<ifl<iwsi Thespecies was intr<iduced i<i Creekside Park in f976 aridby f984 had expanded lo a range l4 km in diameter. Itis also abundant on Corte Madera Creek and was plantedfor landscaping purposes in Greenwood Cove ol'Richardson Bay, whcic it is spreading from seed. Itsseeds will geo»inale in seav'a er, and are produced pro-lifically s<imc 2 nionths earlier than lhe seeds ol Sipur hiuf~riiusu These charactcrislicv and its high pr'oduc ivily<nake it a threat lo the 5uh<tuvnu i irt<iai< u � dominated

tnarsh and lhe upper part of the habitat of Sparnnuf<iiiutu. However, i is n<it cxpcctcd to replace the na-tive pickleweed in the upper part ol lhe marsh, wheresalinilies can he high. InfOmialion on ils effecl on ani-lnal populations is lacking, hut these authOrs state that"until the evidence supports that.Spurtinu dcn~ifl<uu isnol detrimental, «II efforts should be made to control itsSpread tO other i<ication» in the hay."

<ipur in' ul ernif7oru occurs in San Francisco Bayat the mouth of the Alameda Creek Flood Control Chan-nel and abuut 3 km io lhc south. The reason for ils intro-duction and its date of arrival arc unknown Spicher andJossefyn I9ft5!. Aberle f990! reported ihat this speciesw as introduced lo Wi1lapa Bay. Washington. in the latel 8 X!s as packing for oyster spat shipped fmm the EastCoast. lt was later planted in various areas ol' PugelSound to stabil ize shorelines and provide cover for hunt-ers of waterfowl, The species is now considered a ma-jor peal specicv in Puget Sound, Willapa Bay, and SanFrancisco Bay, andmanagers are seeking control rneth-ods Aherfe l990!,

Other exotic plants are potenliai threats to Califor-nia wetlands. Examples are the following:

Me1u!ru< a <p<i n<ftunerrtu, the cajeput tree. is nativeto wetlands in Australia. In southern Fhirida, this spe.�cies has escaped froin hotticul ure and is a maj<ir peal infreshwater wetlands. I is a prolific seeder that can storeseeds on the tree in capsules <millions of seeds pet tree!lor several years wilhout loss of viability and then re-lease them after a stimulus such as fire Drew andSchomer 19h4!. Trees were planted along the peripheryof Tijuana Estuary by homeowners in Imperial Beach,San Dieg<i C«unly. Its potential f' or salt marsh invasionwas not considered because local managers were un-aware ofits pest status elsewhere. Landscapers installeddrip irrigation and planted the trees in iinported soil,The trees established well bul were later removed afterthe inanagement coricerns were recognized.

Mvopr>ruti< face<a< is an evergreen h<irticuitural shrubthat grows lo the size of a small tree. Introduced froinNew Zealand, this species is a conspicuous but local-ized invader of the periphery of salt tnarshes, It is abun-dant along the railroad that crosses Carpinteria Marshand in the campground at Santa Clara Estuary. A lcwplants are present near the Tijuana Estuary. It appears tobe quite salt tolerant but sensitive to inundation. Munz

f974! fists it as naturalized near Ventura, . alifornia.f.urp<ifu<ines edulis Hottentot hg, ala<i called ice

plant! has been widely planted aking freeways, where itforms dense, tnonotypic inats of succulent leaves thatresist drought. ire. and erosion. Ils valued horticuhuralattributev case of transplantation with use of shor branches that readily root at the nodes and rapid vegeta-tive spread! are lhe same characteristics that confer weedi-ness. Eradication is dificult. because small pieces ofplants regenerate and seeds germinate in the disturbedsites where adult plants have been pulled. At l.osPenasquit<is Lagoon, San Diego County, the Departnientof Parks and Recreation has attempted a control program,which will be successful only if nlaintenance is continualto remove new sprouts and seedlings W. Tippets, De-partment of Parks and Recreation, personal comtnunica-tion!. This spetues has invaded a wide range of coastalhabitats, including strand and dunes Williams and Wil-liams l 984!, chaparral Zedfer and Sc held, l 9ftg!. bluffs.and sall marsh e.g.. Los Pcftasquilos Lagoon!.

3.4.4 Invasions After Hytfrologlc ModificationsA sal marsh exist~ as a community in part because ilscomponent plant species can tolerate high salinity, ratherthan because they require hypersaline salt �4 ppt ! soils.Lowering soil salinitie s allows most species lo grow bet-ter, but if low salinities persist, brackish inarsh vegeta-tion can invade.

In many of California's coastal wetlands, tidal fIush-ing is discontinuous. The <tacan inlets of smaller wet-lands and ih<>se with relatively small watersheds tend toclose when sand accumulates during the summer cf. IxisPenasquitos Lagoon case study in chapter 2!. When fill-ing and accretion of sediinent reduce a lagoon's tidalprism, lhe frequency and duration of closure are likelyto increase. If closure is followed bv periods withslrcamfIows that are sufficient to reduce the salinity ofthe lag<ion hut insufficient to break through the sand bar-rier, the wetland will experience a prolonged period offresh v ater flooding, which will lower soil salinity sec-tion 2.1.2!. Under such conditi<ins, lhe following exolicsare likely to invade:

Cotu!a <t utrnopifoli u brass but ons! is a herbaceous,succulent perennial from South Africa. It is cotnmon inboth fresh and saline wetlands. Its seeds germinate atsalt concentrations of 10 ppt hut not 20 pp Zedler andBeare 1986k The species is widespread along the Pa-cific Coast. lt is common in areas that accumulate win-ter rainfall. such as depressions within salt flats of theupper intertidal zone and in open mudflals that receivefreshwater runoff. Al Tijuana Fstuaty, it has invaded in-tertidal flats downstreain of Mexican sewage spills.

Rt<me.r crispt<s curly dock l invades the periphery ofsalt marshes if low salinities persist beyond the normalwinter wet season, Germination tests Zed!er and Beare1986! indicated that sal concentrations less than l 0 ppt

52 TIDAL WETLAND RESTORATIQN

allow recruitmen fr<im seed, hc pl«n rs a perennial bu does no reproduce vegetatively AI t.os Pcnasquit<>sLagoon, San Diego Coun y, If. err'.<!>re< has become aconspicuous component ol' the higher marsh, sharingdominance with D. sT>i < v ra, he native sal grass. Its atiuri-dance has increased significantly in recent years, afterprolonged periods of cli>sure and inundation by localrunoft'.

Tvf>hv dr>min<ansi» ca tail! is a widespread domi-nant plant of brackish wc lands, Its invasion ol' he SanDiego River salt marsh occurred after the I 9�0 liood andsubsequent, prolonged reservoir discharge. Experimen-tal studies showed thai lev seeds gemtinate a salt con-centra iona greater han 2f! ppt and hat seedlings requiredseveral m<inths of low salinity s<iils to develop rhiromesand persist in idally inun<htted si>ils I Be,<re 19!�: Beareand ii~dler 19!�!. f-ield riiiiiii <iong of s<iil salini ies in-dica ed that the San Dicgi>River Marsh w<s brackish inthis case. salt ci>nccri ration n between s ream i<iw and s<>il salinity, whichsupported the cause-effect rel a i<inship be ween reservoirdischarge and changes in salinity in marsh soil. The abun-dance of cattails «iso correlated wi h variations ins rearnflow. The expansion rate was greatest iri l980,when seedlings became established <iver most of the in-tertidal salt marsh. Bi<>mass dropped in 198 I and I 982,which were low-tt<iw years. During I9!�. a year of highs reaninow, the cattail popo!a i<>n l1<>or<shed throughvege a ive regrowth Ino establishment of seed!ings!,because soils were agaiii brackish f<>r par of the grow-ing season 'A..dier and Hcare I 'Nf>!. Since then, he popu-la i<in has declined to rela ively l<>w levels, Under ex-pcrimen a! C<utdi i«ns. rhiZ<>mes resprouted even afterbeing, hei< a a salt c<incentrati<in of 4 5<>< abou ! .3 timesthat of seawater! I'or an en ire year IBeare !98<3!.Reinv;>sion would be likely under pr<>!<inged freshwaterint'!uence, liccause rhizomes can expand rapiii! y, even ifsoil salinities rlre Ilo low eltoilgli o ail<iw germina ionol' secdrc The rec<>rds for T r>ri '<'rrrulis in Aus ra!ja seelolh>wirig! suppor the generality ol' he Iow-salinity in-vasion phenomenon

7; i>rrerrrulii is native trien a is hasinvaded and replaced native salt marsh plants in the es-tuaries ol' he Swan and Canning rivers, There, streetdrains reduce the salinities ol marsh s<iils Pen !9g>3!and experiments have shown that the combination of low-ered salinity and substrate disturbance is responsible forinvasions Zedler, Nordby. and Gr>swold !990!, Toler-ance o salinity increases with the age of the plant, andvegeta ive growth can occur in conditions far oo salinefor the establish nent of seedlings. The seedlings are notgood competitors, vo disturbed soils rrius coincide wi hlow salini ies for seedlings to survive Zedler, Nordby,

arid Griswohl !99 !!. l!rus. iiivr»i<in rs restr>c cd t<> s rectdrains «herc s<»ls arc disrupted and salinr ties arc nearlyfresh R>r unna ura!ly long periods. !nce scedlirrgs de-velop rhizomcs. thc plan beconics in<>re salt toleran «ndmore cornpctitive. A sirigle seedling can establish a el<incarid expand vege a ively into thc native rn >rsh. It is hy-po hesized ha similar mcchanisr»s govern rnv;<sion of«lonal exotic plants in wetlands in S<iu hem California

3,4.5 Invasions After Disruption of SubstrateThe transition from we la»d o upland is oltcn inarkcdby an increase in the species nchness and an abundanceol exo ic plan specierc The origiris <>I exotic species, ac-cording o Munz I l974!, include Eur<ipe Pr> <pi>g<>nmi»r>7><tie>><is!, Eurasia Ru<iiu i>vs<<>f>ifi>iru, 5<iixi>iu>heri<'u!, Chile Ci>rr<vi<'r'iu uru<'rime>r <r i!, Si>u h AI'rica

i fisc>>rt>r'y<r>rrh< >nrrm spp,!, and Aus ralia IA rif>lerx<'nr>7>u<'<'vru!. Abrams I !9' I I s a es ha M, >r<>if>tli>rum

probably arrived in California bef<irc Europeans did!. Tireexotic plants are no necessarily aggressive plan s r'n heirhome coun ry. In England, for instance, P. nrnn<pi li< >isisis valued as a rare plant, and its habi ats are actively man-aged <i maintain popula i<ins A.J. Gray, persona! com-munication!.

These ex<itic species mark areas where the coastalsoils have been dis urbed by agriculture or horticulture,<iumping, sedimen plumes, street drains, disposal ofspoils from dredging operations. trampling, or vehicleuse, The species are also able !. sliipe lhilures, and alluvial tans. The herbaceousspecies may also grow where idal debris is deposi edandmarsh vege ation is srno hered, so long as the elcva- ron is high in th<. intertidal zone e.g.. ex rente high vv u-ter!, These peripheral invaders obviously are siimev hattolerant o salt, bu their tolerance o inundation appearslimited, Their res riction Io bluftk and he periphery ofsalt rnarshes suggests either a low requirement I'or sah orpoor compe i ive ability in nonsaline soils. In Sou bernCalilornia, Arrrt>k vs< nrihac< arv is a comm<in dominantplant of the marsh-upland transition zone Ferren !98',Cox and Zedler 198'>, Zcdlcr and Nordby 19I36!.

The list of alien weeds would probably be length-ened by further studies of the high marsh and the transi-tion zone o upland through<!u C'alii'ornia. This transi-tional area is the mos poorly known habi at ot' coastalwetlands, Most of its area has already been des royed,and what remains has been badlv disturbed.

3.4.6 RecorrtmendetionsCalifornia's coastal wetlands arc a limited na ural re-

source that is jeopardired by invasive exotic species. Ingeneral, the higher marsh and buffer zones are more sus-ceptible to invasion than the lower marsh, because fewspecies can tolera e both frequent tidal subrnergencc andhypersaline soils. Combinations of disturbances. such as

PROBLEMS IN RESTORING WETLANDS 53

hydrologic changes plus soil disrupri<ms, impr<rvc theopportunities for germ<nation of seed»and cs ah i»hn<cntof seedlings. Fx<>tic species can spre<rd rapidly at theexpense ot native plan s, hu hc condi iorts that pronroreinvasion cann<r ;dways he di»covered, Once established.naturalized ex<! ic plant» are diftrcult. il n<rt rnrpossihle.t<r eradicate As «rt<s «f landscape» are rnoditied,pn>pagules ot exotic species are accumulating, increas-ing the p<>tential t<rr irrvasi<>ns <rf ex<>rrc species.

A native plant conservation ethic is needed. I< a-live plant spec<ex should be allowed t<r d<rnrirtateCalifornia's natural c<ras d wetlands, aml receruly rntro-duced species should he c<rnrr<rlle<l, it'»or efindna ed. Therationale behind this judgment is straightforv ard:Califorrria's coastal wetlands are small und few. aboutI;IO in the enrrrc state. I'he renramirrg> v et lands have beenhighly modit ted and severely reduced in area: commonestimates are losses of 7S 9S'/~. The native plants areessential to many native animals c.g., insects with highhost specitrciry! and pret'crrcd by others. The native veg-etation perform~ a v:<riety of functions, such as provid-ing f<r<rd, shel cr. artd nesting materials, that may not besupplied by alien species.

Control measures become essential whenever theinvader is crmsidered noxinus or the affected resourceis highly valued. In California, all the coastal wetlandhahirats are hrghlv valued, not only as na ive ecosystem»but also as habitat f'<rr rare and endangered plants andanimals.

'I'he hest time to control an invasive plant speciesis before it gains dominance. If caught early, thc distur-bance causedby attenrpt» to control exotics wiff affect asrnallcr area, thus reducing chances for reesrabli»hmentof v ceds. Expcricnccs with v ced conrml i<r wetlrlrrds arelimited, and success stories are few. Efforts to eradrcateChrrs<rrrrtrerrr<rm I'rom trllcd areas at Tijuana E»tuary bydisking only retained thc disturbed-»oil c<>ndilions thatfacilitate<i its domrnance. Controlled burning lo elimi-na e seeds and accumulated hiornass <s often ineffectiv

W Tippets, personal communication! and. if done inthe dries weather, may be hazardous to adjacent devel-opnrenrs, Early diagnosis and treatrncnt are essential, anduse of hand tools rather han machines is desirable When

use of herbicidcs is necessary, spot application by handis preferable to broadcast application. Loca! or regionalregulations may require the application of herbicideswi hin a wetland or»tream con idor hy licensed contrac-tors only I Vanbianchi et al. 1994!. Generally. use of her-bicides is discouraged because of potential contamina-tion of wetlands resources.

Invasive exntic plants should be cnntrolled beforethey eliminate native wetland vegetation. Restoringna .ive high-marsh veeetarion will be difficult because

seed mixes to enhance germination of native halophytesare unavailable from nurseries. Hence, gathering and

s<rwin by hand are required; pr<rbfcms should nol belel u<rtil large-scale opera ion» are necessary.

Preventing empress discharge of fresh v<ater canreduce problems. Controlling street runotf to saltnrarshes will help eliminate a major cause ot weed inva-sion. namely lowered soil salrniry. L'ps ream »ed menttraps are certainly needed: hookup» to s orrn drains offerbct er protection for v.etlands. When large drains enteres uarine channels, and connec ion» ro s orm drain~ are

not po»srble, controls at the source <!f he problem mayhave o yield to trea mern of the effects. In such situa-tions. it is important to maintain good tidal flushing,

Vatlve plants shnuld be used to landscape thebuffer zone. Using native plan s ro landscape the transi-tion zone is a simple way to reduce chances that horti-cultural species will invade the wetland. An cduca ionalpr<>gram is needed to show that native»pecies are e»-thetically pleasirrg, thar planting methods are being de-veloped, and that nursenes can produce adequate stockas demand» arise. Desirable attributes of native plantsfor landscaping. ransitional habita s need to be publicized,For example. J<rrr< <ra «<u<nrs spiny rush l is an effectivedeterrent to cars and dogs; a border of these sharp-leavedplants is nearly impenetrable. rtf«!<rsrrr« faurirr<r is droughtand salt tolerant: it requires no care af er initial estah-lishmen . ',via ive insects prefer native plants over exotrcplants such as C<rrfr rrbrrrr«s < drrfi.<.

Thc integritv of native sod should be maintained.Disking. tilling, and grading are n<rr suitable meth<rds <rfweed control; on he contrary, they propagare the prob-lcrn. Instead, na ive vegetation should be encouraged todominate rhe sire. This is done by using small-scale soilpreparation patch rototilling or au<rering I and planting.At Tiluana Estuary. exotic species <vere quick to domi-nate sires prepared hy disking, whereas native sp.cieswere»I<>v, o c<rl<rnize the sites. Disking also altered soilt<rpography and impounded rainfall so har unnatural "fur-rows" of wetter soil developed in he higrh marsh, stimu-lating the establishment ot ex<rric plants l B. Fink, PERL,pcrsonalcommunic ation!.

Continual surveillance is required to control ex-isting problems and avoid future expansions. It isoverly optimistic to aim for eradication of species thatarc invasivc and widespread; ho«ever, reducing the num-ber of exisling pnrhlem areas and preventing spread ronew sites are reasonable goals,

Wherever the approach to a problem is uncertain,small-scaie experimental approaches should be usedtrrst. As an example ot a small-scale appr<rach, wc areexperirnen ing with salt as a weed-control measure, seek-ing the dosage and ttmine of applrcation that will borhallow germination ol' seeds, establishment ol' seedlings.and grov th and reproduc ron <>f native species, whilepreventing reproduction and spread of exotic specie» Kuhn l995: Caliav ay and Zedler, rn prcparati<rnh

CHAPTER 4

Recommendations forImproved Planning

54 TIDAL WETLAND FIESTOAATION

4.1 GOALS AND PERFORMANCESTANDARDS IN RESTORATION ANDMITIGATION PROJECTS

Res or« i<in a<id creati<iii <if hi hi at arc ways to improvethe status of natural biological resources. Sometimestheseactivities are under «ken solely for ha purpose,and some inies they are intended o mi igate damages tohabitat, tha is. o ensure that no net loss of wetland areaor function <iccurs. The distinction between these iwo

lypes ol projec s is importanl: hc lonner nay not re-quire specific pe<formance standards, whereas the la termusl be able o show hal damages h«ve been compen-sated, That is. quantifiable perforinance standards ba~ed<in measurable attributes oust be established, so that re-source agencies can determine ivhether lhe initigaior hanscomplied with the mitigati<in requirements.

The return of a habitat to xi<inc c<indiii<>n that exis edpreviously is generally referred to as restora ion. Becauseecosystems «re dyn«rnic. no single period consti u es heprevious s ale. Furthermore, no de ailed records of pris-

tine condili<ins e.g.. before European colonization ofN<>ith America! are available, so it would be difficult toestablish clear ohdectives. Restoration "t«rgets" are of- cn general, involving reintroduction of tidal influence,removal of fill or accreled sediinen s, rein roduction ofnative species, c<in rol of exotic species, and so 1'orth.A tempts at restoration are sometimes paid for by re-source agencies or nonprofit groups. Mitigation agree-rnen s provide another source ol funding for restorationprojects. Of conccm is whether the restoration plan isdesigned on he basis of the best manageinent practicesor is governed hy the needs of a mitiga or. In lhe lattercase, setacreages of specific habitat types may be im-posed on a disturbed or degraded wetland in ways lh«tare less than optimal I'rom a resource perspective Zedler1996b!.

The ls ational Environinental Policy Act defines miti-gation as avoiding, minimizing, rectifying, reducing.eliminating, or compensating for impacts on naturalresources. The concern de«lt with in this book is com-pensatory mitigation, that is, attempts to make up for dam-ages to existing wetlands, Sectio~ 4f� of the Clean

Wa er Act regulates wetlands by requiring a permit forfilhng or disp<isal of dredge sp<»l and mitigation for un-avoidable dani«ges to we !ands.

hJnrmally, protects that are not water dependen canbc moved tn uplands io av<iid adverse cl' bets on wet-lands. However, some projects that are no water depen-dent are still pernailted in wetlands in Southern Califor-nia. For ex«rnplc, ihe City ol San Diegii is relocatingand expanding an existing sewer pump station within LosPenasquiios Lagoon. Objections o the pump statioAhelped confine construe ion to an area of existing till.avoiding salt marsh. However. the pipeli<ies leading toand trorn the slat on are being cut through salt marshLikev'ise, highways and railroads are no w« er depen-dent, but Interstate Freeway 5, the Pacific Coast High-way, «iid the Santa l'c Railroa<l cross m<isl <if Sou hensCalifornia's coastal wetlands. The continual v ide ning ofthese r<iadw;iys lurther affects the remaining wellandsIn one such project al<irig San Diego Bay, wetland w«»,daniaged by he widening of I reeway 5, a new freev ayinterchange. and a new flood control channel, Three en-dangered species v,ere jeopardized.

4.1.1 Mitigation Issues Related to Goal SettingThe first items that need tn be considered in devekipingcriteria for mitigation are the location of the initigationsite, how inuch area is required, v hether a former wet-land can be real<<red or a new iine must be created, and.

the quality of the resulting wetland. More detailed issuesinclude the functions and values of the werland that willbe lost, the exact type of habitat to be provided, the irnewhen lost func ions are o be restored, and he perfor-mance standards that v ill be used to deter nine when the

project is in cornpliancc. Goals need to be appropriatefor thc region in question.

Restoration or creation? Federal mitigali<m policy Environmental Protection Agency and V.S. Anny Corpsof Engineers I 990! recommends that restoration be givenpriority over the creation of new wetlaiuls fr<irn upland.This policy makes sense in some places, such as prairiepotholes that are drained and farmed and no longer func-tion as wetlands. Re~ oration of former potholes is moredesirable than excavation of potholes from natural

RECOMNENDATIONS FOR !MPROVED PLANN NG 55

upland. How <.ver. v, hei>a hc degraded well<indi still per-forni critical functions, this itra egy ii d<iuhly damag-ing. Firir, the degraded sire is altered with<iu our kiiow-ing what critical 1'unc ioni were hist, and sec<ind. a nerlosi in welland area occurs when a!tera ion of the de-graded site liril! a we land! allowi damage t«anotherwetland C xd!cr ! 996a l.

In Soutliern Calilornia, liiii of hahira ii of en miti-gated hy rei «ring areas liar are m<xlili»d bur still func-tional werlandi; il rarely involves cons ruction of newv et!and habitari lr«<n n<>nwerlands. Thus, a ne loss of

wcr! and acreage occurs, anal <>!ten habitat quality dec! ines Zcd!cr 1996hl. Ai i a ed in 4 Ci ric«r '» Ci «ide n> H~<u-tu>«f Re.u<>r« i<>n Vanhianchi c al. 1994!, "Nothing isgained if we deitroy or damage one wetland ro enhanceanother."

Mitigation ratios. Mitiga ors are «ften requirenalvalue than the damaged sile. Another reason is the dc!aybetween the damage to habitat and he compensation for1<iii. The time for hahira replacement can be long cf;case studies <>n Muzzi Marsh and rog-Le-Hi-Te Wet-land System in chapter '2!.

The California Coairal Commission <i<>rrnallyrequirei a 4: I ra io for habitat replacement. but this ratio<nay nor be sufficient when habitals of endangered spe-ciei arc concerned. Even where 4:1 ratios are uied, lheydo not always sustain wetland area. When existing dis-turbed wetlands are simply inodificd, a ner loss inwetland area occuri: if I ha is desrroyed and 4 ha ot' ex-isting, degraded wetland ii rem«de!ed, the ne !oss is Iha. Such practices do not fu!fiH rhe policy of no ner !ossof we land area. Only the creation of w»r!and fromnonwerl and areai can replace lost wetland <u'reaye.

Habitat qualily. Res ored or created wetlands thathave lower tune iona! value than the damaged iite maynol compensate for the loss, especially il whar is dam-aged ii habitat of etidangered species I cl'. Hurnbo! dt BayMi igation Marsh case study in chapter 2<. Even i�: I <ir4: I compensation is required, a larger area of unusablehabi at will not replace the I'unctional value of I hectarethat is cri ical to lhe endangered p<ipulation. At the least,agencies should require assessment ol the functioning ofthe miliga ion sire before and after impr<>vements and"up-front" mitigation, with "success" achieved and d<x:u-mented bel'ore des ruction of the devcloprnenr site.

Project tirn!ng. Projects are rarely planned with in-definite end points. Usua!!y a specific period is allowedfor compliance. Most often the compliance period isshorter than thc time required for the restored or con-structed wcrland to achieve functional equivalency withthe conditions that existed at the site before any damageoccurred. Although 5 years has been a common timeframe for many projects, longer rnOniloring periodS arenow heing required.

Cons rue iiiii tin>es;rre often lengthy, eipccially whereextensive dredging is required. Excavation and dislx>sa!of dredge spoils «re b<>th lime-c<><iiunring. Off-site dis-posal ol' tin« iedirnenri ii also costly. At Baliquiloi La-goon, fine sediment.i are heinz dredged tment, removing theuildellyinz ian<l and uiing it for beach replenishment,and placing the I'ine mal»rial from rhe reit of the !ago<indredgiiig project in rhe resulting hole. Obviously, thisextends he cons ruction period, and bio a will be dis-rupted for several yeari.

Despite relatively ihort compliance penods, projectsshould he designed to lait indefinitely. and changing en-vironmental conditions should be taken into a»coun .G!oba! chang>ci anlicipated v'i bin 50 yeari includechangei in temperatures. increases in the rate of risc ofiea level. alterations in rainfall patterns, and increases inilorm acriv ily. No policiei require consideration of suchchangei. For coastal we lands, accelera ed rates of riiein sea level need to be considered in long-term planning.Some of he sediinenli that are propoied for removal inmi igation pr<>jecls may ulrimately he needed 1<> offsetrises in sea level.

Transferability nf techniques used in other areas.Res ora ion techniques des eloped ouLiide one region maynot be applicable in another. In Sourhem California,management issues uiually concern endangered specieiand the speciei arc endangered because so much of theirhabitat has been destroyed. From a national perspective,these iystemi <nay be rhe moil difficu!r to restorebecause �! rhe eiidangered species have ipecitic require-menti, �!!it tle v, et!and area ii lett in the region. io thereare fewer propagulei restoratiountry, because of differences in physi-ography and climate. Although there ii no iiinple way toquantil'y dif1'erencei, Pacific coastal systems are subjec ro catastrophic events that pulse t'resh v aler and nutri-ents in <i the werbnds. Thc variability <if annual flowvoluinei in streams in San Diego County ii onc of thehighest in the narion Pryde 1976k ln reviewing miriga-liOri pr<ip«Sais and proiniSeS, agenCieS riced rO reCOgniZerhe unique attributes <il Pacilic Coast ecosysterns. Mod-els developed in we climates rhar have relatively littleinterannual variation are lcail likely to be applicable toregions with low rainfall and streamflow and highinlerannua1 vari a bi!i t V.

4.1.2 Goals for Restoring Southern CaliforniaCoastal WetlandsThe need for a regional res oration strategy for coastalSourhern California ii deicribed e!sewhere Zed!er1996bl. Because so much ol the coastal we !and habita

56 TIDAL WETLAND REsToRATION

has been lost, it is urgent that thc goal of all further modi-fications be o sustain biodiversity. A short-term, small-scale perspective would suggest that every mitigationpmject should have the goal <if on-site, in-kind replace-ment. But when many ol' the mitigation requirements arefor deepwa er fish habitat, and where I.he only place avail-able to create such habitat is shailow-water wetlands,mitiga ion agreemeiits soinetimes allow one habitat typeto be remodeled in o arlother.

A regional stra egy for restoration of wetlands wouldinclude a detailed invcn ory of all remaining habit a s sta-tus report!, analyses of what habitat types have highestpriority for restoration regional needs!. inventory ofplans and mitigation needs in relation to constraints de-termination of' opportunities!, and a mechanisin f' ormatching mi igu ors' requirements withregional resouicemanagernen needs. The firs wo elements of this strat-egy are being undertaken in ihe San Francisco Bay area J. Collins. Western Society of Na uralis s presentation,December 2H, 1994!. where most of the sta e's coastalwetland «rea occurs. The process being undertaken thereshoukl aid eff<ins in Sou hem California. Indeed, the StateResources Agency has called for an inventory of South-ern California wetlands in 1995 C, Deniso T. personalcommunication!. Ex i sting maps of w ed and resources willbe developed iruo a geographic informa ion sys em toaid in summarizing extant habitat types. In addition,Ferren and colleagues �994! have developed a habitatclassifica ion scheme for Southern California wetlandsthat will facilitate categonzat ion and invemory.

Coastal wetlands support the follow ing habitat ypes,and increases in all of these are suitable restoration goals:sah marsh, salt pan. ransition zone to upland, tidal creeksand channels, mudf]ats, sand lats, dunes, dune slack, andbeach, Expansions of the populations of the na ive plantand animal species hat depend on each habitat are alsosui able res ora ion goals. It is clear that sustainingbiodiversity requires protection and expansion of habi-tat. What <s n<it s<i clear is what goaK have pri<irity whenthere are so riianv priority needs.

4.1.3 Performance StandardsThe California Coastal Commission is developing state-

wide guidelines for setting performance standards formitigation pro!ec s Z. Hy r>anson, personal coinmuni-cation!. PERL and Philip Williams Associates areassisting in the effort Ideal 1 v, restoration and creation ofhabitat should s rive for functional equivalency with un-disturbed v e lands. The questions are then what func-tions should be measured, whether simple structuralattributes are good indicators of functional capacity, andwhat attributes should be ineasured to test for functional

equivalency.Functions are processes. Famihar func ions are pri-

mary productivity, decomposition and production ofdetritus, and production of finfish and shellfish. Theseattribute~ have been the focus of hundreds of papers on

wetlands <>I'ilu A bin i<. <<rid iult ol Xfevico coasts andseveral in the P;<c ific Nortliw est. Measurn>g these func-tions is impor ant where fish pn><luctio» is the mosthighly valued furiction»l' wcthirids. Al<uig ihe coast ofSouthern Calif'oniia, v herc here «r» no anadromousfishes, where we lands are oo sniiill to support muchshell shing, and whcic endangered species are of greatconcern. o her fu«ctii>iis tire m<>re valued. Support ofbiodiversity is ot overridin imp<>r ance in SouthernCalifornia, and sever he rnain-tenance i>f »a ive flora and fauna:

~ ivlaintenance of'na ural hydn>l<>gic regimes in bothshort- an,ireme llds, allovvs rccruitmen of marine tauna which arc in olerant of freshwater, Zedlcr ct al. 1994 I aiu1 flora. riios speciesof whicli require lowered salinities for major re-cruiunen Zedlcr und Bcurc I'98 >, Callaway etal. 199 !!.

~ Maintenance of habitats with suitable area, size,shape, and connec ivity. I.urge areas ol consistent idal influence at Tijuana Estuary. with a low ra-tio of perimeter to area and a broad connection tothe river fl<ui<]plain. supp<»t at least 24 speciesci>nsidered sensitive in Ihe region Zedlcr. Nordby.and Kus 1992!.

~ provision of buffers that protect wetlands fromhu-man activities in uplands. sustain habitat for up-land species hat are essential to wetland species,and allow room for the v etland to niigrate inlandas sca level rises cl. scc1i<>n S.S I.

~ Resistarice to disturbances. that is, the ability ofecosystems to sustain natural processes and popu-la iona as habi a s degrade in quality and declinein area. For cxaniple, tidal flushing sustains highsoil sali »ties, which prevent invasiOn ot mostexotic species into the l<>wer intertidal sah marsh cf. section 3.4!.

~ Resilience. tha1 is. he ability of the system to re-cover from shor -term disturbances, both naturaland anthropogenic. For example, cpibenthic in-vertebrates C<ri hi<I<ca and variou~crabs! re invaded Tijuana Estuary v hen tidal flov swere restored after the estuary had been closedfor 8 months.

~ Maintenance of nutrient supply and retention ca-pability, Natural marshes have sufficicn nitrogento sustain tall canopies of cordgrass but not ex-cessive supplies Ihat would generate massive al-gal blooms which v ould smother invertebrates

~ persistencc of vegeta ive cover that provides suit-able nesting habitat and pro ection from preda-tors.

~ Small-scale patchy disturbances to allow recruit-ment of annual plants. Salt narsh canopies do notbecome too dense <>r too sparse to support species

RECOMMENDATIQNS FOR IMPROVED PLANNING 57

.'i le!i tis lhc cilcl« iigcl <'d sa It <narsh bird '.s beak. be-

cause the dis urbancc agents small mammals,wr;<ck dcp<isition! are .sustained a thc appropria escale,

Ecologi st.'i liave nnt developed methOds tOr assess-ing all these functions. Even methods <il'measuring pri-mary pr<xluclivit> hut have been tested repeatedly ineastern v e lands;ire <it' questionable use iri Sou hemC«lifornia On<it' c al, 97K!. Not only do succulent.species tave high hi<imass loss rates. making harvestmethods inaccurate, but also the restricted status of hewetlands in Sou henl Calitornia suggests that harves ingis oo damaging to be allowed as a regular assessrnenltechnique. No standard se <>I measures exists that mustbe made to asses~ the I'unctional equivalency of restoredand natural wetlands.

Bee <use functions require more effoil to measure thans rue ural attribu es. i is likely tha perforinance stan-dards will cmphasire structure, that is, what there is atone specific time. Like a snapshot of the system. the pres-ence and ahundances of vari<ius species, the height ofthe canopy, and the cover of algal mats can all indicatethe presence of various pr<icesses. Yet they must be rec-ognized as indica ors and not presentecl as proof.

I unctional equivalency indexe~. Earlier, a simpleindex of !unctional equivalency for the Conneclor andParadise Creek marshes along San Diego Bay was pub-lished PERL 1990, Zedler and Langis 1991!. Only thebest areas of the constructed marsh. i,e., the areas deemedinosl likely to I'unction the same as natural rnarshes, <s eresamp!ed. 1'he index included 11 attributes. and the con-.structed Connector Marsh was less than 6 !'!r function-«lly equivalent t<i he natural marsh.

Such indexes are subject to rnisin eipreta ion andmisuse. The comparison <il' the Connector and ParadiseCreek marshcs was considered a hest-case rather than aworst-case or an «vcr <ge conipaiison, because the bareand average canopy areas of Connector Marsh were not~amp!ed. Thus, it should no bc c<included that the con-structed marsh was 60"!r as functional as the naturalmarsh. Rather. he data suggested it was less than 60%1'unclionally cquivalen in the attributes sampled. Addi-tionn of other a tributes might have increased <ir decreasedthe value. Also, the manner in which individual resultsare entered into an index affects its iiveiall comparison.The extensive data base of Rutherford ! 989! on inver-tebrate comp<isition was lumped into one value, whereasnitrogen fixation rates were split into surface and rhizo-sphere values, thus emphasizing nilrogen supply more han invertebrates. The comparison was restricted to at-tributes measured in the same piace al approximately thesame tiines, although adding other measures had littleeffec on the index.

Before adopting such an approach as a performancestandard, it would be important t<i determine whe her datafrom the same wetland, sampled over time or space,v ovid be within 80% to 90% similarity. Next, the sensi-

tiviiy of the c<unpartson to he nianner in which attributesare included would need to be determined. Finally, itv ouMbe useful to exphire the use of weighted averages,that is. giving n>orc e<nphasis o sonic attributes than Oothers. Theie may be reason not «> equate he contribu-tion ofsurfa«c nilr<igen fixation ra es with the support nfthe en ire epibenthic invertebrate assemblage, forexample,

PerformanCe Curves. Ken ula et al, �992!suggestedusing performance curves to describe the developmentof restoration sites. They proposed th«1 over a period ofa few years. the natural marsh wou d exhibit a relatively~table conditi<in, whereas the constructed marsh wouldbegin with lov; function<0 s atus and rise o some rela-tively stable level below that ot lhe natural inarsh.Simenstad and Thorn �996! have presented real data forseveral attribute~ of Gog-Li-Hi-Te in Puget Sound. Theirresults indica e much grca er complexity: Some « tributesol' the constructed wetland increased, some decreased,and others changed unpredictably. Reference wetlandsdiffer realistically, wi h equivalency par ly dependent onv hich sire is used for comparison.

The implication that both natural and constructedmarshes have ~table perforntance horizoiual lines! overshort periods is debatahle. Over cen .urics, a representa-tive mean may be useful, but «sho�-term mean may hearli lle relationship lo that mean. Thus. it is reco<nmendedthat performance curves be developed simultaneously fornatural and cons ruc ed wetlands. Although it wou!d bccheaper for a mitigator to select 5-year data sets as therestoration target, the reterence v'etland may performbetter or worse during the asses.smcn period for the miti-gation site.

Long- erm tnonitoring data from Tijuana Estuary andSan Diego Bay suggest an alternative way to track theperformance of a constructed or restored wetland,Callaway and 7edler plotted the absolute condition ofseverals ructural attributes of natural marshes throughtime and lhe relative condition of the same attribute inthe constructed marsh. For each year. thc constructedsystem was compared with the reference site for thc sameyear Fig. 4.1!. The results shov cd tha no slcadyinCreaSe in structural equivalency occurred within the 8-year monitoring program of this 1! -year-<ild wetland.

Performance standards for nesting by the light-footed clapper rail. Assessment of the performance ofConnector Marsh as potennal nestmg habitat for the light-footed clapper rail suggests an addi ional approach thatis appropriate for specific mitigation or restoration tar-gets. Because the basic problem with this marsh is itscoarse, inorganic substrate, which does nol supply enoughni rogen for the growth of lal! cordgrass. a functionalequivalency index that emphasizes cordgrass density ormean height will not distinguish adequate and madequatevegetation. The appropriate measure of habitat suitabi I-ity here is an assessment of canopy architecture, speciftcally the height distributions Ted!er 1993!. Criteria were

TIDAL WETLAND RESTORATION

Fipure 4.l Changes in 7 atlribufes ol sediment solid lines! andcordg rase Spari<na foliose, dashed lines! in a constructed wetlandlhal was lransplanted io cordgrass in 1985 Data from each year areeXpreSSed relalive O the Cendiben Of lhe adlaCenl natural march.Values <1 indicate that the constructed wetland has!ess than thenatural marsh It is difficult to predict if or when the iwo marshesmight become e<tuivalent. i = sediment organic matter; 2 = sedi-ment oral Kleldahl nitrogen, 3 =- stem density; 4 = total stem:ength,5 = mean height; 6 = number ot stems > 60 cm tall, 7 = number ofstems > go crn tall Data ot Caliaway and Zedler lpERL, unpub-lishedl.

developed after a detailed analysis of canopy charac er-istici in varioui marihei with and without clapper railssampled in various years. lr considered the nesting hab-its of he clapper rail e!cia ion where neiti are built,thickness of ncitih tidal levels during the nesting sea-son. and the main causes of neil in<irtii!iry inund» ionby tidal water and preda ion!

The pnipoied ilandard.i are thar tltere b» a !cail 100itemi Of CnrdgraiS per square meter. v ith al leaS 90 Stemi aller lhan fx ! cill and at leaat 3 > i ema taller han '90 cm.These are ro be preient within a iiunpling area 20 x 20m, randomly iamplcd with at leai � circular quadrati.

2each 0.2S in- x~d!er 9931. The mitigation agreement ct Table 2.!!I for C<tniteclor !V!arsh and Marisnia deNaci<in calli for at !cail seven home rangei, each t!.!!-!. i ha, and each having at !cuit l.'s% 1<iw-marih and alleiist ! 5'A high-marih habitat O'.S, Fiih and WildlifeService i 9! ! !. Each h<inle range'. must h;ive at !cail one! 0�-11'I patch of id l1 corclgl iiii,o

l.lnderitanding how lhe habitat serves the species andc<imparing ii tc s where the ipccies d<rei and ditch no neitare v hat led to the cordgraii performance criteria. Addi-tional perforrnancc itandardi for clapper rail nesting sitesshould include adequa e rlitrogen supplies, tidal Hush-ing, forage ipecici, and adequate high-tide buffers. Oncewe work our lhe nitrogen fertr!ization regimen needed tosustain the all vegetation, i should he possible to assessnutrient leve!i in the ioil and inflowing water and pre-dicr the iite'i ability to grow tall cordgrais in perpetuity.Nesting of clapper raili at the Connector Marsh wouldprovide aisurance that tall vegetation, and not urban dis-ttifbancei, has limited their use of the iite to date.

Draft performance standards for salt marsh bird' sbeak. An approach simi!a«o that used for assessing

polcnr ial ries iiig habilar fiir c !tipper rai li c<iri bc ahen rosct suitable criteria fiir reeirahiiihi»enl of iall nlarihbird's beak. Several desigri criteria follow tron> ongo-ing work scc section 2.4.4!. Soili ihould have a exturciiinilar to thar of natural marsh sites that continuallysupport thc .ipcciei, aral tidal liuihing and «levationsihould be the same. The preferred boil ipec iei Die i< hli»spi<'rrrrr. Mori<in br>< ifiri< irrr<rr<rirs, an0 � f�rcihade!. Habitat for ground-neiting bees ih<iuld he pro-vided immediately adjacent o thc traniplant sile. ThenleChaniSlni thar rilaintain Open C uf<>!ries <if hOSt plantashould be present. Small inarnmali are most likely re-

sponsible lor the openings. htough both hurr<iv ing andbrowsing,. Until derernlined orherwise, i ii recom-rnended that habitat f<rr small mamma i bc pr<ividedadjacent to the tranipl mt iite. although anima!i wouldnot need to be inlroduced until canopy cloiure hec<nneia problem. Fina!ly, it ii rec<mimended diat mariy wc!!-separated sites be avai!ab!c for growiiig bird'i beak. so hat disturbancei that might wipe out one colony v ouidnor occur throughout thc lraiiiplanling location.

The rniliga i<ra agreeine»l ihOuld require a«set rlum-her of colonici of bird'i beak. Specific performance stan-dards wou!d then be based <in the size ol each colony total pl ult counts!. an eStimate of seed production meannumber of' iced capiules iet pcr plant!, and furlhcr ob-servations of limiting fact<>ri at each traniplantirig site.Three ro five colonies at Tijuana Esruary could be usedas references, and when the riurnbcri of' pluri i pr<iducedare at least 90"< of the mean colony size, and numberiof seed capsulei produced are srari stically indi stinguish-able from those at Tijuana Estuary for perhaps S con-secutive years. the site could be judged in compliance.I ii poiiible hat some colonies will fail during rheproject, as happeris iri natural marihci; hence, rnitigalorswould be wiie to establish and to inonitor extra colo-nies in order to ihow that the required nunrber hai per-sisted for he requisite time.

Performance standards for rnid- and high-eleva-tion marsh vegetation. The ability of' salt marihes rosupport native plants and animals depends on rhe de-gree of tidal Hushing PFR! !990!. Tijuana Fstuary. wi h

RECOMMEI>IDATIOI>!S FOR IMPROVED PLANNING 59

a long history of tidal lluihing.. iupports 19 native halo-phytes, whereas ai feii as three occur in iitc» wi h littlesahwater influence. Expec at ion» for tully tidal niarshesshould thui be greater than ihoie lor sites with mutedtidal flow, that ii, tidal a<ti<ni provided through culvertior over weiri that <nay be needed to prevent llooding ofadjacent real eitate. Thc three halophytei that occur ina!1 Southern Ca!it'omia coastal wet!art<ki aic />i,! i< hlis.<pi<'<!tu, Fru!!keruu v>uiuliloliu, and !al!<v>r>uu !vrgini< u.These same»pecie» are alio often dense and widespreadin their dis ribulion. At Ieait the lait wi! are highly vari-able in relation to charigei in the degree ol' tidal flushing cf. Ferren'i [19!IS ] historic aeri a!photos ol CarpinleriaMarsh and information on picklcweed dynamics atTijuana Estuary [7ed!er. >Nordby, and Ku» l992J!. Spe-cies of broad ecological tolerance are more likely to dowell in restoration .iitei than ipecics with narrow toler-ance rai!gei for moisture, ialinity, «nd inundation, sogeneral standards !»ay su!Tice for the fomier. Dominanceby one or more of these three hah!phytei. equiva!ent tothat of he reference marsh cs!, may be a suitable perfor-rnance standard.

Pickleweed ii a "matrix' »peciei of the rnid-marshplain, and Be!ding i Savannah sparrows uie the tallestitems as perches to de!end territory and to attract mates White !9!�; Powell 1993!. Hence, standards for canopycover and rnaximurn height not mean height! are needed.Sampling referc»ce marshei by using transect lines intercept within 10-em intervals! and determining rnaxi-mum height in each I-m interval is suggested for eitab-liihing> criteria for suitab!c sparrow neiting habitat.

The niatrix species of the high t!tarsh are 6!u/i< oir!ias!!btern!i!!uli< g!as»wort! and M. l! r<>rul!s Oflheie, taBglasswort has at least three important rolei in the highmarsh: lt piovidei cover for c!apper rai!s that move outof the low marsh during high tides; it serves as a perchI'or Savannah iparrowi; and it iupporti a myriad of spi-der webs. again above he high tide line. Canopy itruc-lure should thus he measured aod roaximum heightsshould be required to be similar to those in the referencewetlands, and the abundance of tall plan s in the twowetlands should he comparable. 11 is recommended 1hatheight histogran!s be developed for cons rue ed and ref-ereiice sitei aod thatsimilar frequency of the tallest stemsbe required.

Speciei that are rarer and roore patchy need m<ireattention and different standards to ensure adiverse marshcommunity. Frequericies of occurrence should hc ai-seised more broadly over larger areas than readilysatnpled by using transect tines! and with less attentionpaid to their overall cover. Presence in I-m intervals orin 0.2S-m circular quadra i should iutfice for their oc-currence. On the basis of our current understanding ofihe functioning ol nondominants, an «ppropria c goal istheir continued presence, rather than some specific height,cover, or biomais.

Species that are deemed ieniitive, that is, threatenedor endangered with exlinction. require 1he grea eit at-tention. At present, theie include bird's beak, Coultergoldfieldi Lusrheni<r gluirrutu!, and olheri listed byFerren �985! and PERL �990!.

Total cover =l X!'/r ininus bare space! is an addi-tional attribute that requirei perf<irmance itundardi, ltis reasonable o require minimum standards for the per-centage of a site that needs to be vegetated, that is, themaximum amount of open space allowed. Natura!marshes typically have quite high cover, with few openpatches in the canopy. Previous sampling programs havenot measured total cover. because the tendency in moni-toring vcgetatii!n has been to place transects in homo-geneous areas ot'continuous cover. Tide pooh and gapscaused by disturbances have typically been avoided,Because open ipace ii patchy in natural marchei, on- he-ground sampling is likely to underestimate or over-estimate it, depending on the bias of the sampling tech-nique. A iiew method for determining bare space usesairborne digital aequi»i ti on and registration imagery romlow-elevation flights Phinn and Stow, Section 6.4!. Atotal-site sum!nary of bare space can easily be made withresolution of less than I m-. ln addition, thc size of eachpatch, shape peritrieter and area!, and distribution ofopen patches can be assessed. Thus, remote sensing isthe recommended procedure for assessing total coverol restoration and mitigation sites.

Finally, there should be a performance itandard for1he maximum allowable cover of exotic plants, Airbornedigital acquisition and regiitration imagery is also prov-ing valuable in mapping and summarizing the diitrihu- ions <!I he more conspicuous invasive exotic plants,such as pampas grass Co>uuderiu.!ellr>unui, giant reed Art<!t<fO donar!, and HOtten Ot fig Curpohro t<s edulisj.By dc!in!lion, undisturbed wetlands v ould have noexotic species plant irilroductions to lhe region are adisturbance!, and reference wetlands will differ in thedegree to which I.hey have been disturbed.

A zero-tolerance policy may be hest for the mostaggressive invaders. pampai grasi, giant reed, Hottentotfig, rabbilfoot grass P<rl!f!ogo!! >nonrireliensis!. andcurly dock Runvr<rispus!. The presence ol exotic vas-cular plan s can and should be avoided by adjusting, en-virontnentai conditions to preclude their eitabliihmentor ipread. Addi ion of sa!t is proving to be a useful con-trol tneasure Kahn 1995!. Exotic ipecies that becomeeitabliihed should bc eradicated to prevent spreading.Even those that are naturalized in many natura! marshes e.g, iickle grasi [Purupholisi!i< <r! uj, brass buttonsl C<rrulu coronopi fi>li u j, and ice plam [Mesen!bryun i!e-nurm < r! stullinun! and M. nodiflornl! need to be mini-mized in conil.rue ed wetlands. Recommendations foradditions of salt titning, amount, and duration I Ihat canelirninatc exotic species ye allow native annual» to ger-minate, grow, and reproduce are heing developed.

60 TIDAL WETLAFID RESTORATION

4.2 A REGIONAL APPROACH TO PLANNING'

MitigatiOn p!at S often inClude off-site projectS, Oul-Of-kind nitigation, and mitigation banks. Plans that pro-vide mitigation credit � not for crea ing new wetlandhabitat but for converting one type of wetland oanother � result in a net loss of' area, because both theaffected site and the mitiga ion site are modified, but onlythe latter is 'repaired." This is a swap of quamity forquality, and it seems to violate thc no-net-loss policy,Regulatory agencies agree, however, hat he minimumreplacemen ratio "may be less than I to I for areas wherethe functional values associated with the area heing im-pacted are demonstrably lov and the likelihood of suc-cess associated with the riiitigat ion pr<iposal is high" En-vironmental Protecti<m Agency and U,S. Army Corps olEngineers 1991!, pp. S-61.

The rest<>rati<>n ot' idal acti<>n 1<> Batiquit<>s Lag >on City i!f Carlshad and U,S. Army Corps of Engineers199 A ic an o T-site. <>u -ol-kind rni igation project. Nearlythe entire lag<i<in is being dredged o mitigaIe damages o deepwater habita that will be lost when the Port ofLos Angeles I4S km north of the site! fills part of SanPedm Bay o improve port facilities. Subtidal areas archeing excavated to support fishes and invertebrates; the idal mudflatc would support shorehirds, and sandyisland cites added in 1994! are to support least Iern nes -ing activities. keintroduc ion of tidal A«wc should ben-ef<t the salt marsh remnant ha persists at the easternend <>I' the lagoon. The ecologic;il issues concern the ex-tentt of dredging needed to accomplish these benelli t s, theecological costs nf eliminating the shallow. nontidal la-g<x>n, and the effec <>f extensive and long-term dredg-ing.

Although remaining wc lands are disturbed, they stillsuppon sensitive speciec. For his reason, further distur-bances carry a rick, even when the modifications are de-signed to enhance the cites. The eAeets ofdredging overl<>ng periods are unknown. Il large areas of little-occu-pied habitat werc available elsewhere in the region, birdstuid other animals <nigh bc able to move aw;iy duringconstruction. Absence of such areas may mean heavyinortali y during construction. If large reserves of ani-inals were present elsewhere, perhaps regionalbiodiversi y could bet er withs and temporary dredging<if coa<ual lagoons.

Because the fish species ha use deepwater harborsare not likely o be thc same ac hose found in coastalembayments, this mitigation project is somewhat out-uf-I'ind. Perhaps even greater latitude should be taken inmitigation rade-t>ffs. Within the regional context, themost important goal is sustaining biodiversity. What ismos needed is a plan hat will avoid fur her adverseeA'ec s or, v hen these are truly unavoidable. allow use

"%>u<ftod tron> Zedler I996I>. @Ecologiczt Society of America.Vitor ed v, ith i>ermine�<�too

of miiigatiiin fur>dc Ii> acconrplish re<»i>nwide goals ina sequence hat will rnoci enhance popula ions ofnative species and <>Acr the cpeciec' recpec ive ecocys-tenrs a grea er potential for sustainahility Zedler1996b!.

4 21 Regional LossesLittle quantita ive informui.i<in i» availablc on the his-torical condi ion or lunctioning of Southern California'stwo dozen cnac <I we larxlc. F<ir three tidally Aushedsites, the historical el ange» in habitat ype were inven-toried by lVlacdonald�99 !; I'able 1.2!. The shallow-water habitats salt marsh and intenidal flats! of thesesites have declined lo 15</< ol thc habita s' hic1oric area,whereas subtidal area hac remained s able lal houghmos deepwater sites have been dredged!, I@los ol theother w' e lands are closed or of en closed lagoons Zedler I9g22! that were historically rri<>re influencedby ocean waters. Cons ruction of roadways throughwetlands, together with increased cedimenta ion tromdevelopmeii in thc watersheds, has reduced 1>dal pnsmsand I'acili ated formation of berm s across their inlets.Tidal inAuence has declined, and salinity reginies havebecome more ex reme as a resul . with he in>poundedwa ers becoming mildly brackish when I'reshwater in-flows are dominant or extremely hypersaline whenevapora ion predominates Carpelan 1967 I. The effectsof these changes on wetland structure or functioninghave not been quantified.

Managers and scientists agree that increased 1idatAushing i» desirable for support of more sensitivespecies Section 2.21, and several enhancement and rniti-gation projects are planned to accomplish his <>bjec-Iive Table 4. I !. The projec s at Anaheim Bay, BatiquitosLagoon, and San Dieguito Lagoon are expressly de-signed to enhance fish habitat as rni igation tor loss ofdeepwa er fish resources. Others e,g., the 2LIO-haprojecl pmposed for Tijuana Estuary! would attenip torestore what has been lost a 1hat wetland in recent

decades. If all the planned projects are eventually imple-mented, significant, major changes will be made t<i theregion's coastal landscape wi h little understanding ofthe consequences, unless we discover what functionsare unique to the shallow lagoons

With so many projects in the region's future, itinakes sense for the final design and implernenta ionphases to be coordinated, so that the ultimate landscapehas an optimal mix of habitat types, however defined.Projects should not proceed independently nor be drivensolely by the needs of the mitigator. It ic noi. uncom-mon for an individual project to include a standard listof targets Table 4.2! with little regard f<ir the p<nen ialof the mitigation site to sustain all functions. The con-tinuing needs of port di.strictc to find sites to compen-sate for loss of deepwater fish habitat portendcontinued conversion of shallow-water wetlands todeepwater channels and lagoons. The best quantitative

Table 4,1, Restoration and Enhancement Projects Planned for Southern California tftfettandsSite Proposed Change

Remove obstructions to increase tidal flowsExcavate adlacent site to increase area of tidal influenceOpen tide gates and increase tidal flows to salt marshCreate access to tidal flow in diked marshesMaintain tidal system tidal basins tor fish have been constructed tomitigate habitat loss in San Pedro Bay!Enhance tidal access to diked marshes and flatsDredge mouth to extend periods of tidal influenceDredge mouth periodically to sustain tidal influenceDredge lagoon to shift it from nontidal to tidalDredge mouth to shift it from nontidal to tidalDredge mouth periodically to extend penods of tidal flowShift lagoon from nontidal to tidalEnlarge culverts and gates to increase tidal flow ratesRemove fill to restore salt marshExcavate fill to create intertidal marsh �2 ha have already beenexcavated!Dredge upland and transitional areas to create salt marsh and tidal-creeksystems

Goleta SloughCarpinteria MarshBailona WetlandLos Cerritos WetlandAnaheim Bay

Bolsa Chica WetlandSanta Margarita EstuaryAgua Hedionda LagoonBatiquitos LagoonSan Elijo LagoonLos Penasquitos LagoonSan Dieguito LagoonFamosa SloughMission BaySweetwater Marsh on San Diego Bay

Tijuana Estuary

'From Zedler 1996b

data available <m habitat loss I Table 1.2! sugges hat thegreatest need is to res <ire salt rnarshes an<i intertidal fla s,rather than deepwater habi ats.

We do nn know exactly h<iv the current wetlandsdeveloped, i.e., what processes shaped existing cornniu-nities or wha rare and extreme even s influenced theoccurrence aird abundance of species. We do not knov,the dependencies among he c<irnponents of the wetland;competitive arid predator-prey interactions are poorlyunders ood. We cannot predict the dynamics <if variouspopulations or that they will persist in perpetuity We donot know what factors confer resilience to species andcommunities.

4.2.2 The Need for a Regional Restoration PlanTwo a!terna ives are sugges ed tn sustain we landbiodiversity. The lira is <i halt damages to v et lands. Inmi igation p<ilicy, the firs priority is avoidance of ad-verse effects. Unfonunatcly, ir is not easy for the regula-tory agencies o deny permits lor activities on priva eland. Even <m public land, developments arc possibJe ifthe project is deemed "good" for the public.'I hus, in theSan Diego area, Intersra e Freeway i has been widenedby filling parts of several coas al wetlands: access roadshave encroached on the periphery of Agua HediondaLagoon, Batiqui os Lagoon, and Los Peiiasquit<isI-agoon. a Hood control channel dissected a wetland com-pJex along San Diego Bay; a sewer pump station is be-ing relocated and expanded within Los Peftasqui os La-goon: and trail systenrs are propOseil to increase publicaccess into Tijuatia Estuary and Swee water Marsh.

The second nlrerna iv e is to conduct all enhancementprolects within a regional wetland restoration plan. acoordinated effort tha encompasses 320 km of coastlineand includes the folh>wing elcmen s:

RECQMMENPATIONS FOR IMPROVED PLANNING 61

~ Charac erizc rhe existing resource base l.existingarea of each habi at type, patch size and shape, c<m-nect vity, isolation! by using National We Jand In-ventory maps and remote sensing imagery.

~ Dc ermine the unique qualities of each habitat type e.g.. impounded lagoon waters may support spe-cies hat cannot use tidal waters!.Se regional goals for sustaining biodiveisit>. andestablish general plans for re aining and increas-ing each habirat type.

~ I,'se existing plans Table 4. I ! and sugges ions toiden ify and map all poten ial restora ion and en-hancement sites.

~ Indicate he most appropriate restoration pr<rceduresfor each site. Several ecological principles canguide thesedecisions Table 4.3! within constraintson what can be accomplished c.g., BalionaWetland and Famosa Slough require ide gates topro ecr urban areas from inundation. which pre-cludes a goal of restoring full tidal flow!.

~ List existing mitigation needs. that is, pr<ijects harhave been proposed.

~ Match needs with opportunities insof'ar as is pos-sible, favoring in-kind mitigation.

- Where no ma ch is possible or v here extensivemodifications are unlikely ro be successful, estab-lish out-of-kind compensations thar contribute oregionaJ goals.

~ 'fhroughout the process, follow an adaptive man-agement approach and carry out research to un-derstand successes and faitures.

A.suitable regi<»al priority would be reesrabtishmen of habitat< rha have been most reduced in area or spe-cies. For Southcm California, he following steps couJdbe taken:

62 TIDAI. WETLAND RESTORATION

Table 4.2. Habitat and Species Commonly Listed as Objectives or Targets in Coastal Wetland RestorationProjects in Southern California

Habitat Type Sensitive Species

Light-footed clapper rail Rallus longirosfris levipes!Belding's Savannah sparrow Passercu us sancfwichensis beldingr!Salt marsh bird's beak Cordyfanthus marrfimus spp. maritirnus!Wandering skipper Lepidoptera: Parroquina errans!Tiger beetle Coleoptera: Cicindela spp.!ShorebirdsCalifornia halibut Paralichrhys. californicus!Least Bell's vireo Vireo bellii pusillus!California least tern Sterna ant<I/arum browni!Western snowy plover Charadrius alexandrinus nivosus!

Tidal cordgrass marshPickleweed marshHigh intertidal marsh

Salt panMud flatsSaline tidal channelsA iparian willowsBird nesting islands

Table 4.3. Scientific Principles That Can Help Guide Choices for Wetland Restoration'

Large systems support and maintain the highest biodiversity. Thus, restoration work with large systemsshould have greater potential for sustaining regional biodiversity

2. Coastal wetlands support greater biodiversity if there are good linkages with adjacent ecosystems uplands,riparian corridors, and nearshore waters! and few barriers to water flow and movement of animals e.g.,culverts, roads, light and telephone wires!. Adjacent habitats provide high-tide refuges resting places andalternative foraging areas for animals that avoid tidal inundation!, habitat for upland species that areessential to wetland species e g., insect poilinators that live in uplands but are needed by annual wetlandplants!, access to water-borne larvae and plant propagules for establishment and reestablishment of nativespecies!, and areas for wetland vegetation to 'migrate" as the sea level rises essential for long-termmaintenance of biodiversity!. Thus, restoration projects should remove barriers and improve connectivity.

3 Specific ecosystem types will develop best if located near or adjacent to an existing ecosystem of the sametype. Some desired species can be transplanted e,g., plants!, but the rest of the native community mustinvade and become established on its own. Nearby sources should offer higher probability for dispersal.

4, Small habitat remnants are likely to have reduced resilience and less resistance to natural and man-madeperturbations i.e . fewer refuges from disturbance, more exotic species. fewer propagules, slow recoveryrates!. lt may be more important to retain and expand on the habitat remnants at the smaller wetlands,rather than add new ecosystem types.

'From Zedler 'i996b.

~ First. deterniine how each site functions as ahi<!diven<ity' reserve.

~ Expand the area ol' these reserves where possible,emphasizing hahi al types th;it have ni<ist declinedin area. This v ill ii»priivc chance» t'or attractingspecies and sustaining he full cornplemcnt of na- ive plants and animals. Tijuana Estu;iry representssurh an opportunity in Southern Califnrnia. l sup-ports 24 sensitive species, and a 200-ha restiira-lion plan has been developed Entrix et al. 19<! D.yet there «rc no tunds to implement it.

~ Next. expand the area of small wetlands. enipha-sixing the type ot'habitat that is still present. Forexample, at San Dieguito Lag<ion, existingvegetation ,<i<lh< <rrniu <'ir.r,riri «i a<id iiss<x:iated spe-cies! c<iuld he expanded rn<ire easily than intr<i-duclllg c<ifdgl ass vf>rn'rrrr<r j<r/irn<d.

~ Once thc expanded hi<idiversity reserves sh<iwpr<iiiiise tiir attracting and supponmg sensitive spe-cies, create such ecosystem types at v etlands thatformerly included them. For example. Los1'cit;isle<los l agoon had lush cordgrass in 193<!

tPurer t<�2!, althnugh it has disappeared. alongwith chipper rails.

~ The last priority would be to create such hahitats atsi es where they may never tiavc <recurredhistorically. There is no historical record ofcordgrass a San Diegiiito Lago<m, '<ir example.

The ongoing planning for enhancement of SanDieguito Lagoon has incorporated several of theseelements. The Calil'ornia Coastal Commission is requir-ing S<iuihem Calitorriia Edison to restore 60.7~ ha ofselt-sustaining functional wetland, with a coinhinationof in-kind substantial f'ish habitat! and out-of-kind prn-vision for rare species! objectives, as a c<inditton for con-tinued operation o the San Onofrc Nuclear CicncratingStation. Eight v e lands were initially selected as poten-tiat initigati<in sites for Southern Calif<trnia Fdison. Ofthese. San Dieeui <i l.agoon an<i Tijuana Estuary rankedhighest MFC I go I h and he f'ormer was selected after alengthy rcviev and public hearing.

Other recomrne»dati<in s included restoration of about36 ha at San Dieguito Lagoon, where channels might bcreadily enlarged to accommodate fish tiahi tat. and about

RE< OMIUIENDATIONS FOR IHIP ROVEO PLANNING 63

24 ha at Tijuana Es uary. where the chances ol'aug<nent-ing populations of endangered species are high. How-ever, Southern C alif<irnia Edison argued successfully I'ora single site. !ni ial hydrologic studies have since shownthat full tidal flushing is hard to achieve at San DieguitoLagoon and that frc<!ucnt maintenance dredgi<ig will beessential. Because the nii igator must maiiuain tidal flowonly so long as the San Onofre station is operated, ratherthan in pcrpetui y, it would bc less risky o construct habi-tat' that can withstand tidal closure e.g., the pickle weedcnmmuni y, which supports Bc!ding's Savannah spar-rows!. rather than to count on long-term tidal flushing.

For long- vmi maintenance of regional biodiversi y,each ecosystem type should consist ol' larger areas andbe present in <nore locations, as was the case historical!y.This is particularly difficult to achieve along thc coastof Southern California, where little open ~pace reinains.This region may represent a worst-case scenario for miti-gation prob!erose il certainly challenges ini igators, re-source agencies, decisi»iimukcrs, and researchers. In re-gions with a larger proportion <if ihc natural habi at re-maining, thc po en ial for on-site. in-hind mitigationshould be greater. Still. a regional frainework can onlyimprove chances of fulfilling the na i<in's no-net-losspolicy, that is, sustaining wetland area and function,

4.3 THE TIJUANA ESTUARY TIDALRESTORATION PLAN

The Tijuana Estuary Tidal Res oration Plan is a modelrestoration project. First, it would restore wha has beenlost at the site approxiina e!y 1 St! ha of salt niarsh and48 ha of intertidal fla s! rather than beiiig driven by theneed for mitigation of other ypes of habitat l<iss tc.g..nearshore subtidal fish habitat: see Humboldt Bay casestudy in chapter 2!. Second, it follows an adaptive man-agement program, recognizing that efforts to restore habi-tat, particularly for endangered species, are not yetassured of success ln order to help develop needed tech-nic!ues, restoration would be done in phases. The firstphase includes an cxperimen al I -h» marsh that will haveareas with and without ex ensive tidal networks, allow-ing an ecosystem-level assessment of the need f' or intri-cate topographic sculpturing. The plan further requiresexperimentation with salvaging of vegetation and soilswhen damage is unavoidable. The remaining part of the198-ha restoration plan would be impieniented in mod-ules, v, ith lessons learned from earlier modules incorpo-rated in o plans for!a er nodules.

Tijuana River National Estuarine Research Rcscrveincludes the Tijuana S!ough Nationa! Wildlife Refuge,managed by the U.S. Fish and Wihi!ifc Service, and Bor-der Field State Park, managed by the California Depart-ment of Parks and Recrea ion. ! ts specific goal is to pro-tect three endangered species; the ligh -foo ed clapperrail, California least tern, and salt inarsh bird's beak.

A program iil' adaptive management Wai ers andHi!born ! 978! with long-tcrin month>ring, field studies.manipulative experiments. and a major restoration pro-grani guides resource management at Tijuana Es uary En rix et al. 1991. Zedler et a!, 1992!.

4.3.1 Management NeedsTijuana Estuary has many management needs It is anurban estuary subject to the !nng- and short-term effectsof a targe human population cf, section 3.3!. The ci y ofimperial Beach surrounds thc northern arm of the estu-ary. Flood control levees in agricultural lands have modi-fied the T!Juana River floodplain. Just upstream. the cityof Tijuana, Mexico. has about 2 million inhabitants.Sewer hook-ups are few, and human was es flow northinto the Tijuana Estuary. The watershed above Tijuana isscheduled I'or rapid and extensive development. At thesaine t<me, the downstream estuary is supposed to serve«s a reserve for research and education, a refuge for en-dangered species. and a state park.

Sedimentation problems. !ncreased sediinen ationfollows disturbance of s<u!-stabi!izing vegetation withinthe watershed, Thrnughou Southern Ca!if<iinia, estuar-ies and lagoons have been fi!ling in rapidly, as hil!sideswithin their watershcds are disturbed and developed.Vege ation that <night slow er<ision is sparse in Mexico,where grazing i» more common and fires occur moreoften than in he United S ates. The extremely erodibles<ii!s move downstream wi h winter rains, and cata-strophic sedimentation occurs at the coax Mugu lagoonlost 40<7r of its !o<s- ide volume because of cumu!ativesedimen ation during thc floods of ! 978 and 19g0 Onuf! 987!. Sedimenta ion is a naturai process, but the rate~have acce!crated, and the lagoon's ability to respond bychanging its conligura ion has been constrained by pe-ripheral developnient s.

Natural events that counter the effects of sedimenta-

tion may also bc augmented by human activities. Forexample, the greenhouse effect may be accelerating therise in sea level and compensatmg sornewha for sedi-ment accretion. However, the average rise in sea levelcanno begin o keep up v ith catastrophic sedimentationaccompanying major floods; the net effect is that coastalwetlands fifl in nore rapidly than they would naturally.

Problems of beach and dune erosion. The beachand dunes erode when winter storms and high sea !evclscoincide, Dunes contribute ~ediment that fills channelsin the adlacent estuary, Suinmer is he rebuilding phasein un annual cycle of beach removal and replenishment.However, if the replenishing sands are intercepted in theirtransport along shore or downstream. the beach and dunesshow a ne loss Inman ! 9I k ln additio<i o the annualcycle, the long-tenn trend is an increase in mean sea level,which gradually moves the beach inland.

Disturbance ol' beach vcgeta ion has contributed tothe deslabiliza ion of the dunes. and replanting effortshave been under way in recent years P. Jorgensen and

B, Fink. unpublished data!, Further dune stabilization,through extensive revegetation effoits. is called for inthe feitoralion plan,

Problems in habitat management. For an estuarythat ii managed primarily for iti native wetland commu-nitiei and endangered speciei, passive management leav-ing nature alone! might seem preferable to activemanipulation of environmental conditions. However, dii-turbancei have had significant effects on the estuary, andthe issue ii not whether, but how tnuch. intervention isrequired to tnaintain native species.

Decades of diiturbance to the estuary and its wa er-ihed have substantially altered the environmentalfactors that con rol habitati, Since 1900, some commu-

nitiei have been toit entirely e.g., w<iody beach vegeta-tion!, and o her new onei have developed e,g�brack iihpondi und mariheik The overall management goal ii t<imain ain the na ural variety ol'habitati. recognizing thaiincrc;ising the area of any <ine habitat type shiiuld notreduce habitat I'<ir aiuither, Single-ipecies nianagementis not deiirable, becauie procedures tha might benefit<ine ipecies mtght adversely affec ano her. Restorationrequires a comprehensive approach, because al eringhabi a in one area can poten ially affect the entire eco-syiiem. Habitati that need Io be restored include the fol-lowing:

~ Transi ion frotn upland to wetland~ Salt marsh~ Intenidal ialt marsh~ Salt pans~ Channeli and creeki~ San<i flat i and mud fluti~ Beach and dunei

~ R i parian ecoiy stem~ «astal iage icruh

4.3.2 The Tidal Restoration Plan'I'he giiali for 'I'Buana Es uary are to iniprove tidal flush-ing enough lo irlain ain atl <ipen ocean inlet atld to createa<id reit<ire iutficient habitat for maintenance of estua-rine hi<id<versi y. Thcie g<>ali are complernen ary, exca-vating sedimenti lhat have washed into the estuary willincrcaie tidal fluihing and expand wetland habitati. Most<if the restoration work will be done in the southern armof' he eituary. where sedimentation has been heaviest inthe pait caid where tidal flows arc mos siuggish.

ln 19II4, the State Resources Agency and the S ateCoaital Conservancy provided funding to map the'I'ijuana River v'a ional Estuarine Reiearch Reserve andni develop a hydrologic model Williami and Swansonl9f�!. This was followed by a 3-year assessment of re-sourcei and evaluation of environmen a! impact fundedby the State Coai al Conservancy in 1988. Plans to re-store full tidal flushing to the southern arm of TijuanaEiluary began with the hydrologic analysis. Williams andSwanion �987! used the I &57 map as a model of whatthe estuary migh need to becotne a fully idal eituary. In

I gS7, the i»outh wai .1 !S in v ide. and Ihe i<htl priimwas eitimate<f to b« l,g niilli<in ni'. Ab<iut 352 ha of

intertidal v ctlaridi werc eitiniatcd i<i lx. present. Tidalsloughs ex ended 9I4 m»iland tovvard the eai , 1524 mnortti, and 6 I 0 rn iiiuih fror» thc <icean inlet. A largearea of open water wai preiciit in hc i< iut h v esternmostpart of the eituary.

Be wee� I gs2 a<id I<!86, iiiaily chiingei <iccurred irlgeoinorphiikigy, fiydr<ilogy.;ind liydriidyoamics Fig,4.2I, Frotn the hii »n«miipi an<i;<crial ph<itos, it wasei ima ed that I !V ot'the historic tiilal priim had beeneliminated. Sedinien i 11<swed in lr<irn ihe watershed andacross hc beach, deperiding on the type of itorm event.With sea i ormi, the duriei were both fla tened andpushed inland. Maj<ir re reat iit' thc beach 90 i 20 m!wai docuniented for the l,<4-year period.

Williami and Sv;inion I 9f<7 I iumntarized the ina-j<ir problcnii that would co<i inue t<i phigue the cituaryif these phyiical proceiiei werc not «hated: ! ! The es- uary woutd c<in inue to lose its ifdal prism, thr<iugh iedi-inentat ion down Tijuana R i ver, <hiwn Cioa Canyon, andacross the beach during .iton» waihovcri. �! We1landsv ould continue t<i he converted to upland habita . �!Fresh v atcr inflov s could shift large areas of ialine wet-land to brackish vvetland. �! Wetland area would con-tuiue t<i decline as a consequence <it' accelera ed rise iniea level. Sl The encr<iachment <il' dcvclopmen in theriver c<irridor would degrade the riparian habitat andincreaic B<iod Iiazards.

The hydr<ilogis i iuggeite<l an exteniive dredgirigprogram Fig. 4.3! Ihat would foe ui on hc iouthern armof the es uary, They alio propoied a major new channelin the nor hem arm to conncc the tidal ponds to thcTijuana River channel, a <neasure that would maintaintidal acceii to Oneonta Slough af'ter the migrating dunepinchei <iff its current iipcning to Tijuana River and theocean inlet.

Mappitlg iif rcioul'cei and aisciiment ot e<tvir<iri-mental impact lollov ed, wi h preparation of an envi-r<inmental impact review and an envirorimen alimpact itaternent by Entrix ct al. �99I!. A biologicalanalysis was undertaken to determine what resource~would be affected by the proposed dredging Enrix ctal. 199 1 k

A constraints map Fig. 4.4! was developed fromthe field studies; it de ails all areas coniidered sensi-t'tve, either for the typ» of cornmuni y preient or hcoccurrence of' rare and valued species. For example, thearea of transition o upland that occurs south of the tidalponds wai considered too valuable to be dredged. Saltflati and high marsh habitat near the Border Field over-look had high densities of Belding's Savannah sparrowsand hence were coniidered too sensitive f' or conversionto low marsh,

Modifications to the l987 plan were suggested toincorporate new information and ideas. It was proposedthat a channel be cut near the visitor ceriter at Tijuana

RECDMfifIENDATfONS FOR IMPROVED PLANNfNG 65

PAC

Figure 4.2 Historical changes that have reduced the tidal prism of Tiluana iEstuary. Ivlodified from Williams and Swenson t 987.

TIDAL WETLAND RESTORATION

Figure 4,3 Tt!uana Estuary "ininimum dredging plan" designed torestore the tidal prism, Two river training harms t>otd lines! weredesigned to dwert sediment inllows away from excavated Chan-nels and to accommodate dredge spoils. Modified froin Williamsand Swenson 1987

Estuary to improve tidal circulation. enhance opp<>ttu-nities for nature interprets ion, and reduce thc need tobring visitors into habitat» of endangered species. Thehydrologists v ere asked to redesign the dredging pro-gram to avoid sensitive area~. Florsheim et al, tin Etitrixet al. 199 I ! redesigned the hydrol<>gy plan and respondedto recommendations f'<ir an adaptive management ap-proach, wi th two phases I a model priijcc t<i precede full-scale restora ion! rind a modal.tr approach subunit s thatcollld be cO is rue ed «h funding became available!.

4.3.3 The Model ProjectThc model project has three f'ca urea: First. an experi-mental inarsh Fig. 4.C! of at leasl h ha will be con-structed to determine how excavation of tidal creeks willaccelerate developmen of the ecosystem cf. section4.1.C!.

The second feature is a new channel to connect thenonhem end of One<mta Sh>ugh to he northern tidalp«nd. In addition to impn>ving idal flows, it will en-hance nature in erpretation and increase habitat acre-age. The channel will be excavated along the toe of thefill on which the visitor center is located and will pro-vide ready access for iriterpre ive activities. Several ofthe estuary's habitats will be created wi hin the excava-tion, including tidal creek. mud flat, lower-to-uppermarsh, and transition to upland. It is likely that the pub-lic will join the project, much as volunteers have par-ticipatedd in planting and ~ceding he coastal scrub veg-etation that landscapes the site of the visitor center.

The third feature is I.he widening of Oneonta Sloughwhere a buried hard pan prevents inland migration ofthe channel. Unless the hard substrates are removed, tidalflows would eventually be pinched off as the dune gradu-ally encroaches from the west. Maintaining OneontaSlough as the tidal acces~ for the northern arm of the

estuary will niakc it unnecessary ti> cul i ncw channelsouth of the tidal pi>ri<ls, thus prcscrviiig ih» transitionalv etland-upland hah< a s tha i>ccur there.

Disposal of dredge spoils remains <in issue. Dredg-irig will generate spoils of vttrious qualities. Sandy spoils nay be used t<> replenish the beach arid dunes, buttine-textured spo~ls will need tre dep<>xi ton in an au-thori7ed deep-sea dump site is aii additional option. Atthi» writing, only the plan for beach disposal of spoilsfrom the sccxm<1 and third fc;iture has been approved.

4.3.4 The 200-Hectare ProjectIt is expected that thc 2 X!-ha cxcavati<in Fig. 4.f>! willhe implemented over two or morc decades, because iheproject will he costly and funds are not currently avail-able for thc work. An innovative, modular approach willacconiplish two adaptive managcmcnl objec ives. First,it >x i tl he p<>ssi hie to matc h each t'uridirig opportunity wi hthc restoration <>f <me or m<>rc h;<bite modules Rather

than proceeding piecemeal, the res oration v ill be corn-pleted in modules to make up the 200-ha program. Sec-ond, monitoring of and research on ea«h coinpleted rnod-ule will improve the next. As problems are recognized,correc ive measures can be built into later constructionplans. As restoration nie hods arc improved or new ideasdeveloped, they can he incorporated in o subsequentmodules. The essence ot' adaptive management is a dy-nami«plan that can improve as knowledge accutnula esand restoration science progresses.

Protection from future floodirig and sedimentation isnot assured. Recause Tijuana Estuary has accumulatedvast antounts of sediment in recent floods. there isalways the possibility hat the restoration site will be re-filled by flood-horne sediments, It is not yet clear howthis can be avoided or accotmnodatcd cf. section 3.I !.The <>riginal restoration plan called for two river train-ing berm s Ibuil from dredge spoils!; tlie larger would be2 4 km long and 18 m high. Subsequent plan s eliininatedboth herms because the environmental impacts were con-sidered excessive.

4.3.5 Restoration Research NeedsSeveral questions remain about how to conduct the res-toration project. In response to these needs, the restora-tion plan Entrix et al. 1991'I listed several experimentalprojects, pointed out alterna ive restoration measures, andcalled for supplemental analysis of the environmentaliinpact once choices are made. Issues requiring furtherresearch and analysis include he following;

Efforts to salvage soil and vegetation. Dredging torestore channels will disrupt small areas of benthic ani-mal communities and creekside vegetation and infauna.To the extent possible, areas of native vegetation will heavoided; where unavoidable, a salvage and revegetation

Rgure 1.5 The 8-ha model marsh that has been planned to allowexpenmental comparison ot areas with and without tidal creek net-works.

RECOMMENDATIOHS FOR IMPROVED PLANNING 57

nts map for Tguana Estuaryitive habrtat to be avoided infor purposes of restoring the

as = water; shading = senw-areas; hatching = sensitive

PERL.

Figure 4.6 Revised tidal restoration plan for Tifuana Estuary. Thenver berm mbdldI was later eliminated. Modified from Entnx et al.t99t.

program will be undertaken. As discussed later Icf. sec-tion 5, I, I!, the fine sediments will be needed to providea suitable substra e for the pniposed tidal marish. Thereare no precedents for sediment salvage work of this type,and details have no been planned. Experiments are be-ing de~eloped to determine he size and depth of soilcores needed to retain native vegetation and soils, in-cluding root zones and seed banks.

Propagation and replanting. When the Itrst resto-ration site has been excavated, studies will compare ratesal which species become established with and «ilhou revegetation. The new channel adjacent to lhe visitorcenter will most likely house these experiments. Therewill be many opportunities for public interpretation,making Tijuana t'.stuary a major demonstration site for!ilute-i!f-the-arl restoration meth ids.

Yeosystem development «ith and without tidaI ~creek networks. Severs! I'uiictiiiris iii «ctlands are hy-pothesized lii relate to thc presence of idal creeks withinthe suIt marsh plain. These are rapid increase in nutrienlpools. enhanced plant growth, denser and more diverseinvertebrate popuhilions, and enhaiiced use by birds. Totest lhese dependencies, Ihc II-ha marsh will be subdi-vided in <! six areas, three with aiid three wi houl tidal-creek network» incised inio the marsh plain Fig. 4.5!.Development rates ot' thc cciisystein under these twotreatments will be ciimpared o dcterrnine the need forconstruction of tidal creek~, «hicli will add to the inirialcost of niarsh construction throughout tile 2IIO-ha restti-ration program but reduce the time rc Iutred for achiev-ing the goals of restoration

CHAPTER 5

Methods of EnhancingEcosystem Development

5.1 AMENDING SOILS TO PROVIDE TALLCORDG RASS CANOPIES

Cordgrass canopies fail to gr<iw all and robust on sandy,nutrienl-pOor sedimen S. Using agricul ural pr ineiples,i I'ollows that sedimen s could be amended in wa> s thatwould build up the soil, impr<ivc the nutrient status, andincrease plant height. Yet developing specific recommen-dations has proven complicated.

5.1.1 The Importance ot Organic MatterOrganic content is one of three key facuirs with eleva-tion arid drainage! that influence marsh produclivi y Iiti sch and Ciosselink 1986!. In mature wetland sys- ems, he organic matter in sediments is he major stor-age pool of nulrients Haines 1977, Langis el al. 1991!,and a large par of these nutrien s is stored and recycledwithin the ecosystem Milsch and Ocisselink 1986!. Theimportance of organic matter for nitrogen cycling is notsufficiently clear, but wc do know hat nitrogen is a lim-iting nutrient in salt marshes Valiela e al. 1976, Covina d Zedler 1988!. Borh nitrogen lixa ion and denilril'i-cation rely on the type and amount of organic matterpresent. Additions of organic ma ter s imulated nitro-gen fixation in both natural and constructed marsh soilsalong San Diego Bay Zalejko 1989!. Orgailic rnat ter insediments also improves hc capacily for cation ex-change.

Lnfortunately, low levels of organic matter in sedi-inen s seem lo be characteristic of constructed wetlandsalong the coast, not only in Southern California Langise al. 1991! but also in xlorth Carolina Craft et al. 1986,1988! and Texas Lindau and Hossner 1981! cf. Table3.1!. These studies agree that low levels of organic mat-

ETHODS OF ENHANCING ECOSYSTEM DEVELOPMENT 69

ter limit nutrient supply and slow the rate of functionaldevelopment in conS rue ed marShes.

Organic ma ter accumulates slowly in marsh sedi-ments. Accumulati<in occurs when decomposition ratesare low, hvause of low oxygen levels and inhibitory acidsin anaerobic soils at low pH Kilham and Alexander1984!. The major sources of organic ma er in the soil insall nlarshes are though to be emergent macrophytes Craft e al. 1988!. especially those with dense root sy»-lerns and particulate matter that se les out of the watercoluinn For the Pacilic Coast, accumulatioil ol peat israre to absent Frey and Basan 1978!. The natural refer-ence marsh at San Diego Bay Paradise Creek! had only2.0 � 2. i~Jr organic carbon percentage <fiy mass. I.angisel al. 1991!. Because it is uncertain how long a con-structed marsh w>ll take lo rnatch the organic levels andnutrient s atus of natural wetlands, the ti ne required forfunctional equivalency cannot be predicted,

5.1.2 Shortcomings of Sandy Substratea atSan Diego Bay Mitigation SitesStudy oF a 5-year-old construcled coastal weliand in SanDiego Bay indicated hat sandy dredge spoils are poorsubstratcs for intertidal wetlands. The sediments had lowlevels of organic matter and nitrogen, which impairedthe deveiopmeni of ecological t'unc iona Langis et ai1991!. Soils and vegetation at the const uc ed Connec-tor Marsh and the natural Paradise Creek Vlarsh werecompared in detail when the former sile was 4-5 yearsold. Signifi can differences were found in soil organicrnatter, nitrogen. nitrogen-fi xa ion rates Zalejko 1989!.sulfate reducnon, and sullide production Cantilli 19h9!.Low concentration~ of nitrogen appeared to liinit bothplant growth Langis e al. 1991! and consumer species.Epibenth c inver ebrates were only a third as abundantat Conneclor Marsh as at Paradise Creek. Marsh Rutherford I 989; Scatolini and Zedler 1996 I,

In the summer of 1990, 6 yea s after Connector Marshv as constructed, differences still existed between it andthe natural marsh, Cordgrass at the constructed marshhad only 60'7< ol the biomass of that at Paradise Creek.Plams were dense but generally shorter han in natural

! TIDAL WETLAND RESTORATION

marshes. The vege ation was judged inadequate for sup-port of preda ors, including beetles ha con ro! herbivo-rous insects and the endangered light-foo ed clapper rail Zedler 1993!. In 1992, when the marsh was 8 years old,the plant canopy declined; at the same time, damage byscale insects was widespread l3oyer and Zedler 1996!.In 1994, 10 years after transplantation, cordgrass cano-pies were still short Boyer and Zedler, unpublished data!.

5.1.3 Limited Effectiveness of One-Time SollAmendmentsMy colleagues and I hypothesized tha 1he rate of' devel-opment of constructed we land ecosysterns would beaccelera ed by adding organic rnatter and nitrogen to thesubstrate. We tested thi» hypothesis in a newly cons rue edsalt marsh by augmenting the organic rnatter and nilro-gen in the sediments Gibson et al. 1994! We expectedcordgrass to show inc reascrl gr<iwth in proportion to theamoun of nitr<igen «dded, whether I'rom inorganic ororganic sources. Wc further ex pected that nitrogen poolswould be increased after the addi ion of aniendments especially amendments with low carbon:nitrogen ratios!and that fertilizer containing inorganic nitrogen wouldalso increase nitrogen pools, but for a shorter period. ThefieM experiment took place within a newly excavated 7-ha marsh, known as Vlarisma de lslacion, located alongSan Diego Bay. Amendments included straw carbon.nitrogen = g4 , alfalfa carb<unnitrogen = 12!,and ammonium sulfate inorganic nitrogen!,

The organic amendments rapidly stimula ed growthof cordgrass. Signi icarit effects on plan biomass oc-curred rcs early as 2 m<inths after planting. Highest growthwas oh ained when aifalfa was added, either with <ir with-ou inorganic nitrogen. The combination of inorganic ni-tmgen and straw increased gniwth significantly more thanstraw alone Gibs<in et «I. I 994!, indicating that the straw-amended sys em was more nitrogen limited than the al-falfa system Fig. 5.1!. Rototilling appeared to have anadverse effect, biomass was consistently low in he ro o-tilied control areas.

Overall, the growth da a indica e tha alf'alla causedthe rnos grow h because it <ontainedmore nitrogen thanthe other treatments However. relaiively little of the ni-trogen added wa» recovered by the aboveground plantmaterial Gibson e al. 1994!. A substantial frac1ion ofthe readily mineralizable nitrogen was leached or deni-trified in the month before planting. Results of an assay decomposi ion in litterbugs! done in 1992 indicated thatas much as 80% of the added nitrogen can be mineral-ized in the firs month Gibson 1992!. Because destruc-tive sampling was not compatible with the long-termobjectives of the amendrnen study. v'e did not estimatenitrogen storage in belowground biomass. Even if rootsand rhizomes had eight times the aboveground biomass Vahela et al. 1982!, the fraction of nitrogen retained bythe vegetation was small.

In the first yeiir <ri Iie s udy. iitrogeii-rich organicmatter alfalfa! increased plant growth but not sedimentorganic rnatter and ni nigen pri<r s I iibs<rn et al. 1994!,Thus, it was no surprise that iii the second year, plantgrowth was still limited, even though the rffec s nf treai-rnent were still visible I-'ig. S. I !. The highes cordgrassbiomass dcvcloped in aiicas amended v ith alfalfa. How-ever, the maximum hiirmass in venr 2 was only abouthalf that of the standing crop <if a natural c<irdgrass marsh c.f. data in Winfield 1980!.

5.1.4 Why Short-Term Fertilization Does NotEnhance the Nitrogen PoolIn natural marshes. the reserve ol mtncralirable <irganicnitr<rgen accutnulates and is mair< ained by decaying plantmaterial and root exudates. The associated vegetation per-sis s thrriugh c<rn inu<rus turnover <it'nitr<igen within therhizosphere and with ncw iiiputs only occasionally aswith I'looding!. In na ural marshes, one-tiine aniendmen sdo not pr<rduce this necessary nitrogen pool. I<in effect oftreatment could be shown in hc organic carbon pools 5tnonths July 1990! or 7 months ISep ember 1990! afterainendrnents were added. The data indicate that mosi oi'the organic mat er was mineralized. and most of the m-trogen released, in the weeks irnrnediately after addi ion.These I'indings were confirmed by the results of a de-composition experiment with buried lit terbags reportedin Cribson et al. 1994!, and by those of the following.more extensive, experiment, which explored the role ofsoil texture in re aining inorganic and organic amend-ments. In the latter experiment, we also tested waste prod-uct» kelp wrack. horse manure! as novel ways toenhance the nutrient pool niore effectively and morecheaply 1han by adding alfalfa.

We hypothesize< that amendments would be retainedmore readily by finer than by sandier soils. The field ex-periment was s ar ed in March 1992 in a disturhed areaadjacent to Paradise Creek Marsh at an elevation judgedsuitable for cordgrass. Existing sediments were loamysand 84% sand, 6'7r. sih. and 109< clay!. The texture ofthe transported sediment was sandy loam to loam �0-62% sand, 25 � 30% sih. and 10 � 20'7a clay!. Nitrogen andcarbon contents of both the existing and transp<irted sedi-rnents were less than 0.17r,.

The mass of nitrogen in each of eight ainendmentswas 96 g of nitrogen per square meter. The amendmentswere as follows: low dose of alfalfa hay, high double!dose of alfalfa hay, kelp, horse manure. amrnoniurn sul-fate. sulfur-coated urea slow-release nitrogen!, alfalfaplus clay, and fast-release nitrogen plus clay. The twocontrols were clay and sand with no added nitrogen. Afterthe soil amendmenLs were added, soil parameters totalnitrogen, KCI-extractable carbon and nitrogen, porewatercarbon and nitrogen, sulfides, redox potential, salinitv.and pH! were measured 4 days, 7 days, 2 weeks. 4 weeks,

METHODS OF ENHANCING ECOSYSTEM DEVELOPMENT

600

500

eit 400

E

Otg 300CgE0

200

100

0

N added.

Treatment: Untilledcontrol

11.2 42 53,2 96 107,2

Straw Straw + Alfalfa Alfalfa +Nitrogen Nitrogen

NitrogenTilledcontrol

Frgure a.l Cordgrass biomass Iesiirnaied from data on total stem lengrhl during the first and second years affer ainending soils wiih organicand inorganic nitrogen. Plants grew better with high addition of nitrogen N! � x axis shows grams of N adaect-and pedorrned better in year 2after vegetative expansion: yei the highest standing crops were only half the biomass of marshes in natural cordgrass. Modified froin Gibson eial. 1994.

5.1.5 Producing Tall Cordgrass Vegetationwith Multiple Additions of Nitrogen

Kurhann Rover orrd./nr Zedjer

2 months, and 4 months later. Vutrienrs were rncasurcdia both sediments and porewater wells �0 cm deep!.

'Nitrogen was released in a pulse and was rapidly lostfrom both fine and coarse soils and for both i>rganic andinorganic amendments, as indicated by I oral Kjeldahl ni-trogen TKN! levels 4 and 7 days after fertilization Eig.5.2!. Vanabitrry was high and appeared to obscure anyeffects of trearrnenr; no significant differences werefound. At 4 days, soil treated with fast-release nitrogenplus clay had the highest mean TKN �.6 mg nitrogenper gram of soil!, which compared favorably with maxi-mum levels found in local natural niarshes: 3.01 mg iii-trogen per gram in Paradise Creek PERL, unpublisheddata! and 2.38 mg rutrogen per grarrr in Tijuana EstuaryCLangis et al. 19911. However, subsequent TKN levelswere less than half the initial levels. Soil TKN showed

no patterns after the first week. Soil exturc did nor ap-pear to have an effect on nitrogen retention. suggestinethar higher concentrations of clay arc needed. In all cases,the total amount of nitrogen present 1 year after trear-rnent was considered inadequate from a biological per-spective.

Because the one-time soilamendment Gibson et al.1994! was insufficient to produce canopies in a con-structed niarsh equi valent to those in a reference marsh.an experiment ivas done in the constmctcd ConnectorMarsh ro examine the effect of extending the period offertilization. We used biv eekly applications of urea foras little as I month and as long as 6 months. Resultswere examined ar the end of the first grosx ing seasonC,19931.

We continued one I'cnilizer treatmenr for a second

year C 1994L One set of plots fertilized for 6 months in1993 received the same number of applica»<ins during1994. v:hereas another set was not fertilized in the sec-ond year. Ke hypothesized thar the effects of treatmemduring the first year v ould he retained through accumu-lation of nutrient s in rhe xiii Is or storage in belowgroundtissue or, alteniativcty, that t'ertilization fnr 1 year mightnot be sufficient ro sustain fall cordgrass vegetaiion. Ar

.5 week after fertilization 1 week after fertilization

5

F

3 4ee

F 3

ZZ

24>Y

I0

0z 0 4>

v0 C0

0

0Vi

CDfnCD

O.O

CI

CDCt

CC>CDii

+Z

0 v .cnViCD

0 Z 0

n>

0CD0CDV>

CD ZCD

+ CDZ

e!><n jCD

Figure 5.2 Mean total Kjeldaht nitrogen TKN! in soil aBer inorganic and organic nitrogen additions Number of samples � 4; error barsrepreSent C 1 S.E.

he same tinle. we Ci>t»pared sh<>rt-ter»t t'Crt>lltnilii>n In 4dit'trerenl n!onths. Statistical tulalyses were b;»cd <>n aI<it;tl <!t It! Ireatnlents and seven replicatcs Buyer arid/re< ter, unpubl!shed data!.

The vege a itin resp<!!Bled signlfican ly to the «ddi-liiin <>1 nitriigcn. In 1993, ad<lili<>ns of nttr<igcn causedIncreases ir< both Ihoveground hionl;>ss and ti>liar nitr<i-gen In C< it>r>C< ti>r M;Irs h. Late in the season, C<irdgrass inIhc plots re<>fe<'I with 13 applicati<>as of lcrtilirer had hehiglicst tiit:tl slen! length. Next, in order, were he pintsIrc;i ed with tt and 4 applic;iti<ins. Thc plants In rhe ci>n-tn>l plnl s tlait 'It!<.' low<tel tnlal slelrl lellgth. In at! Cases.tl'Ietul 1<iiii>I nltn!gen correl<>tert wi h rhe;I<no<tnt i!t IIIIfog<'.n id< «. t. I I,'In s n'I plots trealc<t OIIIV W>ce. wtttl ulna.<pplieil;tt different in!ca during he growirlg seasoti, didnot ditter iil tiital stem length. f' or aboveground growth.Ihe durat i<in <>I fertl! iaer treatmen S �Otalamnunl added!was m<ire nnp<>!tant than the <ming of the additions.

After heing tcnilized. Ih» cordgrass canopy was all.<nd robust by August and September in 1993. All fertil-ize<I plots met the criteria IZedler 1993! t'or cordgrasscanopies sui ;Ibte or nesting by clapper rails. whereasthe control unfertilizedl plots did n<il. However. just 1year later I August 19941. only the set of plot~ fertitizcdin both 1993 and I 994 had enough tall s ems to meet thecanopy height criteria. Thus. betowground biomass didnol sti>re sufficient nilrogen to produce a tall canopy thef<>ltow ing year. even when nitrogen was applied biweeklythroughout the growing season. t>lor was soil nitrogen

total Kjeldahl N and KCI-extractahle Nl increased withfertilira i<>n in ei her year, supporting our hypothesis thatnitrogen is poorly retained in the coarse soils of he con-s ruc ed marsh.

Cordgrass growth was generally less robust in 1994than in 1993. C>rca cr grow h in 1993 in both fertilizedand c<introl pl<its wa» prohably ass»cia ed with the Janu-'lry 1993 flood, which borh lowered soil salinity andadded nutrients. Stem length» and densities were alsogrea er in 1993 than in 1994 in rhe natural marsh at Para-dise Creek. The lack nf a response to fertilization atParadise Creek in 1993 was further evidence of the sub-stantial effec s of flooding. Addition of nitrogen had noeffect <>n stem density, s crn heights, or foliar nitrogen in1993, suggesting that he cordgrass of this natural marshv,as not nitrogen tirnited immediately after the Aood.Because this conflicts with resul s of other studies of fer-tiliration of ptants in a natural marsh e.g., Covin andZedler 191 8!. v e think that the tlood provided a pulse otnrtrogen and low salini ies in early 1993, amelioratingthe usual timitat>on by nitrogen. Similar flood effects havebeen reported for Tijuana Estuary Zedter e al. 1993!.

In summary, nitrogen fertilization for a b-monthperiod during a flood year produced c<!rdgrass canopiesthar were comparable to those in natural nlarshes, butthis effect was not sustained. At the end of the secondgrowing season, cordgrass canopies were nol suitable fornesting by clapper rails except in areas that were fenil-ized in both years.

METHoos QF ENHANclNG EcosYsTEM DEvELoPMENT 73

5.1.6 Impacts of Nitrogen Fertilization onInsect Pests

Kuth<rryn 8<ry< r anil J<ry Z< <ll< r.

ln conjunc ion with thc cxperimem juit described, weasseSSed the responie o fertilizali<in <if an exiiting popu-lation of scale iniccii H<rliuspis spur'll nu, Ho noptera:Diaspididae! feeding <>n lhc leaves <rf cordg<ass iri lheconstructedmarih Boyer 1994: B<iycr and Zedler 1996!.Because many itudici have shown hat ler iliza ion in-creaies the damage cau.ied by herbivores Pfeiffer andWieger 1981, McNeill and Southw<r<r<t 19g2, Bryant etaJ, 1987, Lightfoot and Whitfoid 987. Strauss 1987,Johnson 1991!. we werc coiicemed ha fertilizing atConnector Marsh nlighl exacerbate thi» i<ifei ati<in. Al-ternatively, others have found that eiivironmentaBystressed plants are note suiccptihle to major damage byinsec s K»erer and A wood ! 973. Mattson and Addy1975, White 1976, Redak and Ca ei 1984, White 1984,Mauson and Haack 1987. Louda 191 g, Larsion 1989!.Low amounts of nitrogen in th» i<iili in thc construe edmarihes of Sweetwater lxla ional Wildlife Refuge arelikely to be an environmental i ress f' or cordgrass. poiii-bly allowing an increase in thc population of H<zliaspis.Stressed plants may be more nutritious because of greateravailability of soluble nitrogen and carbohydrates White1969, 1974, 1976; Rhoades 1979, 1983!, Also, stressedplants, with limited energy and nu rien reiources, mayallocate less energy to defense Rhoades 1983!, bothchemical and mechaiiical. allowing growth of popula-tions ol phytophagous insects,

Once juveriile iniecti were observed on thc leaves ofnew cordgrass shoots mid-Aprit, 1 993!, we began mak-ing biweekly estimates of Huiirzspi s dcnsi ies. We usedabundance classei t<i eilirnate he number of Haliuspisper ste n: c Jass 0 = 0, 1 = I � 9, 2 = 10 � 99, 3 = 100 � 999,

and 4 = 1000 or morc. Although diipersal occurred inIwo main pulsei in 1993 late May and late July!, ourhypothesis tha timing of Huiiuspi s disperial might in-fluence the resul of fertilization was not supported

Contrary to our predic ion, nitrogen fertilization didnot exacerbate Hali u.spi.s damage to cordgrasi in the con-structed Connector Marsh. Long-term fertilization �0applications over 20 weeks! appeared o reduce Huliuipisdensities relative to the density in control plots byAugust. Although early-season establiihment offf«lirzspis was greater in the ploti treated with 12 appli-ca ions of fertilizer � applications at that time! than inthe controls, his trend in abundance reversed by Auguit,when the control plots contained many mote items in-fested with large numbers of Huliuspis ha<i Bic long- erm fertiiized plots did Fig. 5.3! Mean abundance perste n also became loweit in the long-tenn fertilized plots.

Lower abundance of Huliuspis hy the late season in he fertilized plots nay have been due to one or more ofthe following: increased a lack by predatory insec i that

use tall plants as a high-tide refuge; dislodging o 'Haliuspis particularly juveniles! through abrasion ofsharp-edged leaves: more diff cult style penetration andprolonged attachment onhardened leaf tissue: oi relieffrom the stress caused by nitrogen limi ation. possiblyleading o lower availability of ioluble nitrogen and car-bohydrates or increases in chemical defenses,

Plots fertilized only in March, April. June, or Au-gust did not differ from con rois in mean abundance ofHaliaspis. The insects were never abundant in the fer-tilized or control plots in the adjacent natural marsh.Concerni that cordgrass 1'ertilization might provoke dam-age by scale insects were allayed, but other herbivorescomplicated our study in 1994, Patchy damage by lepi-dopteran stem-boring larvae and their predators smallmammals! occurred in the experimental plo s in 1994,beginning in July. Although coritr<il plots showed theleast variability and ploti treated both seasons the inos ,no plo s were exempt from damage Boyer and Zedler,unpublished data!. Other areas re<note to our fertiliza-tion study were also damaged, in both constructed andnatural niarshes,' therefore, we lack direct evidence that

this herbivory was promoted by fertilization of cordgrass.This study suggests that fertilization of constructed

salt marshes in San Diego Bay nay proceed withoutconcern that Haltaspis outbreaks will be facilitated.Other problems <nay develop. especially if larger areaiare fertilized and diA'erent consumers are attracted tothe plo s. Our experimental progra n has been expandedto test the effect of fertilizing patches of cordgrass thatare large enough to attract clapper rails to nest. To de-termine how long fertilization v ill be required, we be-gan an experiment in 1995 that inv oli ei fertdizing plotsof cordgrass for 1 � 5 years, We will co n pare plants. soils,and herbivory at the end of each growing season.

5.1.7 Recommendations for ImprovingRestoration of Cordgrass

Kuthursn 0<rvs r and Jrtr A rll< r

Because we found that n<trogen wai not retained in thesoils after the first icason of fertilization and thatbelowground s orage wai inadequate to sustain tall cano-pies of cordgrasi hrough the iecond year. tong-termcorrective action ii needed. We recommend using con-tinual fertilization over multiple growing ieasoni osustain tall canopies, as required in the mitigatio~ agree-ment L,S. Fish and Wildlife Service 1988!.

For future projects, we reCOmmend hat restaratiOnsitei hc provided with a surface layer of fine sedinaen s.Because it is so difficult lo create .iuitable habitat fornesting by clapper rails in areas with sandy soili, werecom nend ialvaging and reusing fine-textured soilsfrom the areas that will hc lost to development. Whenrestoration projects are undertaken as pan of a mi iga-tion program, he rnarshes that are to bc damaged ihould

74 TIDAL WETLAND RESTORATIOhf

APRIL 11150150

100 100

50 50

Ct m a m

JUNE 7150

100

50

Ci riJ C! «U

AUGUST 2150

100 100

50

0

Figure 5,3 Nuinber of cordgrass stems that supported different abundances of Haliaspis Iclass 0 = 0 insects, t = t � 9. 2 = 10 � 99, 3 = f 00 � 999,4 = I 000 or more!. The control and the 12-application treatments were compared in April, June, and August f 993. The total number of stemssampled in seven 0 t 0-m quadrate is shown in the upper right of each graph

1505

100

««I

50

LU«:

0

O

150Z

0CO AJ «0 I CV rrt

Hali' pis Abundance Class

have a comprehensive salvage plan, so iha p!ants, ani-tnals, and soils cari be i»iivcd i be evaluated when large areas arefertilized. It is uiiclear v he her the patchy clarnage causedby stem-bnrers or mainmals in our experiineiit v as re-lated o fertilization. and such daniage iieeds <the cliiselywatched. Furthercorrective actionmay he needed tocur-tail outbreaks of pest species.

Our expcriencc w»h the IO-yeai-old constructedmarsh shows tha it is difficult lo compensate lor dam-ages to clapper rail habitat, especially on coarse sub-strates, Other fac ors may limit use of this nitigation si eby clapper rails, such as the adjacent I'reeway, con arni-nants in stree runoff, <higs and cats that can prey on birds,and power lines which a ract rap <>rs that can prey onrail chicks, Because there is no guarantee that habita useful to clapper rails can be created in urban settings,we reco nmend no f'urther damage to the fev remainingmarshes thar are used by this endangered species.

5.2 EXPERIMENTAL APPROACHES WITHMESOCOSMS

John C<rf/<<N av and.lnv 2«JI<v

A wide variery of techniques might be used to accelerate he developrnen of ecosystems in restoration sites, butour work with ni rogen amendmcnts suggests that pre-liminary experimentation is needed o develop success-ful method~

5.2.1 The Value of Experimentation BeforeRestorationRigorous evaluation of restoration techiiiques is oftendifficult if done on a large scale in actual rest<i ation sites.The roar of tryir!g diff'ercnt methods will be high if thearea is large; also, harvesting plan s or rapping animals o assess experimental treatments may conflict with ihegoal of creating habitat. Thus, most attempts at restora-iion are large-scale, unreplicated rials, and statisticalanalysis of the results is not possible, Because of the con-straints in evaluatiiig techniques on a large scale in res-toration sites, it is best to v i>rk <iut ncw techniques in asmaller scale experimental setting bel'ore restoration.Field conditions can be approximated m<ire closely hy

METHODS OF ENHANC NG ECOSYSTEM DEvELOPMENT 75

using rnesocosrns medium-size, outdoor experimentalunits! than by using tabora ory experiinents. Testing newtechniques in mesocosms may indicate pitfalls before thetechniques are applied to large areas with great cost andlittle benefit.

5.2.2 The Tidal Mesocosms at Tijuana EstuaryA new facility at Tijuana Estuary has allowed us to evalu-ate the usefulness of mesocostns for testing how hydrol-ogy affects the development of mid-intertidal salt marsh,We planned the mesocosms to support pickleweed be-cause it is the most widespread dominant plant in saltrnarshes in Southern California. We varied wo factors,tidal flushing and freshwater inflow, which determinethe degree of wa er circulation, the salinity of channelwaters and marsh soils, and, ultimately, the compositionof the plant and aninial communities, Our hydrotogictreatments mimicked conditions typical <if mid-intertidalmarshes throughout Southern California. including natu-ral fully idal! and nodified coastal wetlands that wereeither fa! impounded fi.e., subject to tidal flooding andfreshwater inftows but no able to drain! or bl excludedI'rom tidal ac inn i.e., with freshwater inputs and abilityto drain. but with idal inflows precluded!.

The 24 mesocosins were planted with pickleweed andirrigated with fresh water to aid establishment. Whenpickleweed achieved 80% cover in al! rnesocosms. fresh-water inflows were terminated and the tidal treatmentswere initiated. Eight rncsocosms were left open to fulltidal flushing, 8 mesocosms were fitted with tide gatestha were opened on incoming ides and chised at hightide o impound seawater. and the reinaining 8 mesocosrnsv ere fi ted with a gate that excluded tidal inflov s and aone-way valve that discharged any runoff. During thelast 6 months of the expcrtmen , fresh water was addedlo 4 mes<ic<isrns in each group of 8. resulting in 6 experi-meiilal treatments: 3 tidal regimes, each with and with-out fresh water.

5.2.3 Determining Factors That LimitEcosystem DevelopmentAn unexpected problem that we encountered with themesocosms provides a lesson for both future researchand rest<iration projects. The substra e used to constructthe mesocosms was unsuitable for rapid development ofa pickleweed canopy. The mesocosms were located inan area of old fili material, and the soil had a much coarsertexture about 60'lr sand. 20<7< silt, and 20<rr clay! thanthat in the natural marsh less than �'< sand. about 20".<<silt. about 70% clay!. Because of the coarse substrate.subsurface drainage in ihe mesocosrns was much greaterthan in na ural salt rnarshes. The mesocosms that weredesigned to itnpound water drained easily via subsur-face seepage Fig. s.4!. and water levels v;ere similar tothose in areas v ith idal ac ion, where w aier v,as removedvia surface drainage.

at>I

c 10

EC 5

C

a. 0

g- 50 2 4

Inundation Treatment, days

Figure 5.4 CompariSon of aCtual rneSOcesrn drainage with ex peeledimpoundmeni curve 4 expec ed � � observed. Data col-lected by J. Roland, PERL

Natura I ial marihei are charac eriaed by fine-grainediedii»en i. v hich inhibit druinagie and create anaerobicconditions. Anaerobic condilioni ilow the rate of decom-posi ion and incrcaie accumula ion of soil organic mat-ter which i» importan o many we lund functions. Theuccumula ion of »rgar»c rnatter funher slows dramagebecause organic soili have high water-holding capaci y.The magnitude of the cft'ecr of improper substrate he-carne clear in the meit .nims, and the importance ot'sub-iurface drainage wai documented.

The probienr of excessive drainage indicates the im-portance of ciiniidering iuhsrr ate conditiiini when plan-ning we land reilorat ion pr»jecli. Withou hc proper sub-i ra e, n will bc dif'ticult ro ri:i i!ie Intp ir'Ialit wi'. landfunc ion s. Subi rate coniidera1ioni have hcc n evaluii cdin iither wetland rei orat ioiii I :raft et ul. I gt 8, Langii e al. 199I!; however, lhc focus has been on the low marsh,iri areas dominated by cordgraii, and or> nulrient con-ccn ra i«ns and Ihc amoun ot organic matter present.Subsurface drainage ii more cri ical at higher elevatiiini,where idal inundu ion ii leis frequen and ioili are sub-jec o drying and hyperialini y.

A second problem that exaccrba ed the effects of poorwater retenliirn wai due to the intertidal post ion and lo-ca ion ol the niesocosms. The meiocoiini were exca-vated to ft. l tr I 1.9 rn! lvf LLW, and thev should have beeninundated by many high ides during the summer andwinter ex remes, Hov ever, he meiocosms are far fromthe mou h of the estuary, which means that tidal rangesare a tenuated. and fewer tides than expected inundatethe marsh. We had to pump idal water into themesocosmi to mimic the deiired inundation regime wet-ting dunng all predicted tides over fi. I ft MI.I.W!. Obvi-ously, locating a restoration ii e far from the tidal sourcemeans that elevation» will have o be lower than those ofsites near rhe ocean inlet 1o benefit from the samehydroperiod fi.e,. same frequency and duration of idalinundationl.

5.2.4 Consequences of Coarse SubstrateThe firi c mscqucncc iit' course iubitra e was difficultyin eitablishing pickleweed. Where iubstrates are suit-able, his ipcciei ii a good invader. «s thc "weed' part ofits name iuggeili. We did n i an icipate difficulty in get-ting pickleweed to grow fnini either seed or transplanki.However, it l<n>k repealed traniplanlation through earlyiuminer to dc vclop thc desired caniipy t,ibout f10"7c cover!by fall. High i ilini ties I s0 -fiD pp !;ind low soil mois- ure werc likely cauiei,

Sail salinitici in borh hc impounded and tidalmesucosnts becaine quihc low in winter and extremelyhigh in summer fFig. 5.5h Where tides were excluded.hypersalinity wai even more extrcme, hecauie there waslittle oppiirtunity for iurfacc diicharge iuid salt removal.These results suggest a generalizatirn rhar coarse soilsincrease thc range ol'.ialinities that a wetland will expe-rience. Low ialinitiei can encourage invasions of exoticspecies, and hyperialine conditiiini stress even the mostsuit-to! eranl halophytei.

CLa lgn

eSD

nJun Aug Oct

1992Dec Feb Apr Jun Aug

1993

Ftgure 5,5 SO4 Salinity of me SOCOSms under tidal rreairnenta, nt = 8rnesoccsins per treatment!hrough June 1993, n = 4 thereafter.

rides excluded � + � fully tidal � 0 � tides impounded.

Over time a res ored wetland ii likely to accumulatetine-grained material bccauie ot the slow water veloci-ties tha are typical of we land hydriiliigy, and this maylessen the ini ial differences in texture in surface iub-strates. However, the ra e of accumulation of scdirnen sin tidal wetlands ii about O. l- 1.0 cm/yr, so changes intexture wili be ilow. Organic matter and nutrients willalso accumulate in the sediments; however, the rate ofaccumula1ion of bo h ii likely o he sliiwer in coarselygrained sediments. Wetland functions will be los dur-ing this period of accumulation.

Because coarse soils increase subsurface drainage,increase the range of soil salinities leading to extremehypersalinity in summer!. iand slow the eitablishment ofpickleweed, it follows that providing the appropriate soiltexture will accelerate marih developmen .

METHODS OF ENHAt4C hlG ECOSYSTEM DEVELOPMEN7 77

5.2.5 Conclusion and RecommendationsOur tindings call atten i<>n ti> Ihe i>upi>ri«nce uf provid-ing subs rates with appropria e soi 1 texture at res orationsites, especially in the high m«rsh. Iri the 1'uturc, resu>ra-tion plans need to consider thc coridition ol' ihc proposedsubstrate, whether it is subsurface material to be exca-vated. dredge spoils, or other rn« eri«la. We reci>minendthat any natural marsh sediments th« «re destined to hedamaged through deve!opnten be reinoved and s ock-piled for later reuse in the mitigation si e. This is !ihe!yto be the most suttable nteth<>d i>l' ensuring proper sub-strate conditions if thc mitigation site has coarse soils.Otherwise, significant arnendrnent of exist>ng substratesmay be necessary. and this is n<> «!ways successful see

tion 5.1!.

5.3 ARTIFICIAL WETLANDS TO AUGMENTUSE BY ESTUARINE BIRDS

Jnv ad!er and frarha>x> Kns

The value of natural wetlands ro bird popuhttions is wellrecognized, and declines in waterfowl numbers are of-ren artributed to losses in v et!ural area. lf the des ructionof wetland reduces bird popo!arions. hen adding wet-land habitats migh improve the situation, This idea wastested a Tijuana Estuary in the la e 1980s.

5.3.t Construction of Shallow Wetlands fromUpland at Tijuana EstuaryFreshwater wetlands are though to have occurred his-torically near sa!ine wetlands a!!along the ci>«st of South-ern California Swift et «I. 1993!. Few of hese wetlandsremain. and it is unc!car v:hat ri>!e .hey played in sup-porung resident and migratory birds. We hypothesizedthat providing shallow freshwater wettands near TijuanaEstuary would lead to an increase in he populations ofbirds using the es uary. by providing a different type ofhabitat, more open wa er. a id refuges during high tides.

Funding from rhe State Resources Agency, Envlron-menta! License Plate Fund, and he State CoastalConservancy made it possible o test he habitat-augmen-tation concept in a general manner. Xow'ever. v e couldnot determine whether the birds that used the artificialwetlands came from the nearby estuary i,e.. a local shiftin habita use! or from elsewhere >.e., new birds wereattracted ti> the area!. Because sh«lli>w, standing freshwater is rare at Tijuana Estuary, we suspect that bird usev as proportional to the amount of habitat made avail-able and hat the wetlands attracted more birds to thelocal region than would otherwise have occurred here.Only a long-term study of both the estuary and thc artifi-cial wetlands, including banded birds, could determinehow much local bird pn>ductivity could be enhanced bywetland construction.

Between 1986 and !987, more than 70 wetlands wereconstructed to the southeast of Tijuana Estuary w i bin a28-ha site at 18 X! VIonumen Road. The site had previ-ously been used for agri culture, hu aerial photos showedit had been vacant since 1967. The land had been pur-chased for the Nationa! Estuarine Research Reserve anddeeded to the City ol San Diego. which provided a long-ter n entry permit to PERL.

Shallow basins depth, 0,3 � 0.6 rn! were excava edin sandy sediment that had accumulated from previousf!oods, All basins were tined with coristruction-gradep!astic, partially refilled with soil. and watered with anirrigation system. Bi addi ion, an estuarine channel wes of 1800 !v!<>numen Road was deepened to allow pump-ing of brackish wa er into ~elected wetlands. The art!fi-cial we lands differed in size, salinity, and amount ofemergent vegetation. Comparison of bird uses in thewetlands allowed us to determine what wetland cons ruc-tion echniques work best to attract differem bird spe-cies.

Construction of thc artit icial habitat occurred m fourphases. First. we used a Bobcat to excavate three smallwetlartds in the spring of 1986 to work out techniques.Second, after locating a si>urce of larger and stronger ptas-tic, we excavated 15 small �.1 x 30.5 m! wetlands in thesutnrner and fall of 1986. !n the third phase. we con-structed 54 sma werlands �. 1 x 30. S m! and !8 largewetlands �0,5 x 3G.S m!: hese required a bulldozerand werc completed in April 1987. Maximum size wasdetermined by the size of plus ic liners that cou!d be ob-tained and manipulated, Because both the smaller andlarger wetlands were suscep ib!e to canopy closure bvemergen plants, we pumped estuarine water into one-third of the 1 reshwater we lands. a! lowing it to evaporateand create hypersaline condi ions that reduced emergentvegetation. Using this technique. in phase four we cre-ated one large �.8 ha! unvege ated wetland with a broad,unvegetated shoreline. The project was conducted byChris Nordby. Barry Dubinski, and other PERL staffmembers; the wet!ands were constructed. studied. andmaintained for 3 years at a total cost of about 5! 23. XX!,

5.3.2 Attributes of the Artificial WetlandsWetland vegetation developed in a!t the impoundmentssoon after water was added PERL. unpublished data!.Tvpha don>iirgerrsis, Scirpus robbers us. and S. >Iney> a!linvaded on their own; Tv pha was the mt>st aggressivecolonizer. Suhmergent vege ation included Pr>rermoge>i>rrfili forrnis, P la ifolius, and two genera of rnacroalgae;Che>ra sp. the stonewort! and hIottnr sp. a bluegreenalga that forms gelatinous colonic~ or irregular balls!.JVoste>e species fix nitrogen. Vegetation became dense inmuch of each wetland. even though the on!v nutrientsources were the soit and rainl'all. Later. birds probablyeonrributed additional nutrients.

78 TIDAL WETLAND RESTPRATIPN

Anii»uls hal <>ionized the waler were cou tcd tdetermi»c wh<ther food was present for use by birds.Using dip nel and figh ~~~p~, we deinvertebrates in thc water column and in the b nthic sub-strate lm<irc than it!t! genera, PERL, unpublished data!.Zx>op4»k «>n included cladocerans and cop p ds insectsincluded mayflies, dainseltlies, dragonflies, ~ater boat-men, hack swimmers. water a riders, whirligig beetles,predatory <1 v irig beetles, mosqui oes, arid midges. Physidsnails were abundant in several we lands.

~<tttr Insect species c immonly f'ound in the artificialwetlands are indicia<>rs of' specialized, clean-water habi-

Titc pi e<lu ory divirig beetles Rhant<<s sp. and Agabus<!<sine<,er<er«v «nd the hack switnmer 8«enoa sp. are rarein the regi»n because of ihe poor water quality sewage-laden river water, stree runoff, and agricultural runoff !.yet t»ey bc can>c abundant in the larger freshwater wet-lands ~ I I << '/<<>rii> i <u I<'/i< uiii n, the salt marsh water boat-man, wus 1'<iuiid in liigli densities at he salme mud tlat.1 is an itt<f iciit<ir <if healthy salt marsh and wetland habi-tal C, f<it<g in<i, l .S. Pish and Wildlife Service, pers<inalcommunicnii«nf. The occurrence of these importantpredut<iry sp cics is notable, and the lack of mosquitooutbreaks»tay be due o their abundance.

ln Deco>»her t<>t�. we added mosquito fish Ci«m-hiixiu uffir<is! o it!of'the large wetlands to provide foodfor he larger wading birds, and in June l<>88, we addedlarge-m<iuth b tss I 'tfi< rrifuerns .«>Jr>r<>i<>es! to the samewel 1 iiri<l s .

5.3.3 Use ot the Artificial Wetlands by Waterefras8>rds visit i»g the wetland» were surveyed approximatelyweekly f'r<i»i Junc 22, 987. throug>h May 30, 1988. bvusing estahlished r<iules and two 2-m-tall platforms.Overall, 32 species of water birds and 30 species oftenestrial birds werc observed using the wetlands Table6,1 !, Some species appeared as soon as the wetlands wereconstructed. and they remained throughout the year <ifst<idy. Abundant in thi» group were mallards Anuspf«rrrjryr«'! u». <oi>ts Fali««rn>er<«<n«>, herons, egrets,and snipe C!u>hn<te<> gnilin«x<>!, Waterfowl showed asecond pattern <if use: they arrived in the late surnmcrand early frill, stayed over the winter, and departed in thespring These included pintails Anas a<. < a!, Amencanwidgeon Anas <tmer«r<na!, green-winged leal Anas< rec< a!. northern shovelers An<ra c1vpea «>, ruddy ducks CJrvuru j un>ut<'en«s!, and huffleheads R«cepha!<tufhze>f<r>, Shorebirds such as sandpipers C«!idris sp !probably also belonged to this group, but they were tooinfreqoen tO disccm a palter i. As a third group, localresident shorebird species black-necked stif s, killdeerand American avoc«s! became abundant in spring andnested an<t produced chicks around the artificial wetlands.

The larger wetlands were highly attractive to waterbirds; ducks were he m<ist frequent and abundani users PER[, unpublished data!. The wetlands that were

consistently most attractive to birds had substantialblooms <if macroalgac m<irc than 60~in cover !, perhapsas a resuh of bird use and rapid nutrient turnover, '1 hebirds were indifferent to he presence of fish; piscivo-nius species that v erc c> pecied o be attracted to pondswith fish werc not often present arid were never abun-dant. The smaller wetlands became overgrown v,ithcattails and bulrushcs and <sere less used by water birds.Of the 32 species sighted, only 19 S9"k! v'ere seen inthe small wetlands. Those found in the smaller we1landswere priinarily solitary. v,aders �2 specie~, with occa.sionally a coot or a green-v inged teal!. Although linleused direclly, these wetlands may have provided insect<that were consumed by bird» elsewhere.

The 0.8-ha saline mud flat attracted additional andsignificant bird species to the PERL v:etland complexWhereas ducks were the primary users of the large 1'resh-water ponds, shorebirds commonly used the mud fla PERL, unpublished data!. Avocets, stilts, and kilkiecrnested al the mud flat and elsewhere where lov' coverwas available. A hcnr> hctwccn thc tw.and we conclude that the broad open area» were he <nail<attrac1ion. Neither exotic plants nor dense vegetation fromnative species became a problem at the saline mud f1at.Invertebrates, initially hr<iughl in with the estuannewater, provided a source of food for the estuarine birdie

53 4 Cortcfusions

On the basis of our experiments and observation~, wcdrew the following conclusions:

~ Artificial wetlands are used by p<>pulations of'native birds; they pr<ivide additional habitat andrefuge during times when native habilats arc un-available extretne high tides, sea storms, floods.etc.!. The wetlands also provide lov -cost arliti-cial habitats that can suppon native plant. in< erte-brate and bird species

~ Larger wetlands attract more water birds thar smaller ones do. Ducks are the most numeroususers of shallow, open-water habilals.

METHODS OF ENHANCING ECOSYSTEM DEVELOPhllENT

Table 5.1. 8ird Use of Artificial Wetlands at Tijuana River National Estuarine Research Reserve

Common Name Latin Name No of Sightlngs >of SurveysPresent

WATER BIRDSGrebes � sp.!

Pied-billed grebeHorned grebe

TotalPodrtymbus podicepsPodiceps auritus

9.32.37.0

Rails and Coots � sp.!Virginia railAmerican coot

TotalRallus limi colaPuli ca americana

21712

2169

74.44.7

69.8

TotalArdea herodiasArdea albaEgretta IbisEgretta thuleArdeola striateBotaurus lentiginosus

23

12 12

5 21

37.220.9

2.32,37,04.72.3

TotalRecurvirostra americanaHi mantopus mexi canus

26634

232

62.827.953.5

Plovers � sp.!Killdeer

TotalCharadrius voci ferus

119119

62,862.8

Pandion haliaetusElanus leucurusCircus cyaneusAcci pi ter cooperiiButeoj amai censi sAquila chrysatosFatco sparverius

2.344 279.14.7

3264.7

32.6

Ducks �2 sp.!Dabbling ducks 8 sp.!

MallardNorthern pin tailGadwallAmerican widgeonBlue-winged tealCinnamon tealGreen-winged tealNorthern shoveler

Diving ducks � sp.!Ring-necked duckLesser scaupRuddy duckBufflehead

Herons and Egrets � sp.!Great blue heronGreat egretCattle egretSnowy egretGreen-backed heronAmerican bittern

SHOREBlRDSStilts and Avocets � sp.!

American avocetBlack-necked stilt

Sandpipers and Snipes � sp.!Western sandpiperLeast sandpiperYegowlegsSpotted sandpiperMarbled godwitDowitcherCornrn on snipe

LAND B!RDS*Raptors � sp.!

OspreyBlack-shouldered kiteNorthern harrierCooper's hawkRed-tailed hawkGolden eagleAmerican kestrel

TotalAnas platyrhynchosAnas acuteAnas streperaAnas americanaAnas discorsAnas cyanopteraAnas creccaAnas clypeataTotalAythya coliarisAythya affini sOxyura j amai censi sBucephala albeola

TotalCalidris mauriCalidris minutiliaTrirrga sp.Tri nga maculariaLi mosa fedoaLimnodromus sp.Gaitinago gallinago

1798596260

18120

216057864

16234

42113

1301

16622

9112

95.486.048.81 1.625.6

2.353.530.216.351.2

4.77.0

25,641.9

51.22.39.3

'1 'l.64.74.7

27.9163

Bg TIDAl. WETLAND RESTORATION

No. of Sightings % of SurveysPresent

Latin NameCommon Name

Hirundo rusticaHirvndo pyrrhonotaLanivs ludovicianusPsattrtparus minimusTroglodytes aedonThryo manes bewickiiAnthus spinolettaDendroica corona laCarduelis psaltriaCorpodacus mexicanusGeotypis trichaslcteria virensSturnella neglectaAgelai us tricolorMotothrvs aterZonotnchia melodi aZonotri chia eucophrys

Flycatchers � sp,!Black phoebeSay's phoebeWestern king bird

Sayornr's nigri cansSayornis sayaTyrannus verticalis

58.111.64.7

Other � sp.lMourning doveAnna's hummingbirdBelted kingfisher

Zenaida macrovraArchi loch vs annaCeryle alcyon

20.92.34.7

tVote: Birds were observed weekly from June t987 through May 1988. Data are total individual birds sighted andpercentage of surveys when the birds were sighted. Group percentages are for surveys when one or more birds frontthat category were sighted.

'Only presence-absence data were recorded for landbirds.

~ Cattails invade readily and dominate shallow fresh-water wetlands. Emergent vegetation rapidlycloses the canopy in shallow ponds. Exotic plantscan become a problem in artiflicial freshwater wet-lands.

~ Saline mud flats are easily const txicted if an initialsource of saline water is available. The salt be-comes concentrated via evaporation and preventsestablishment of vegetation. The artiticial hyper-satine mud flat successfully attracted shorehirdsand other water birds.

~ Artificial v ctland» require cnntinuedmai~tenance.They are not self-sustaining, Needed are a watersupply and iiccasiiinal checks for damage to theplastic liners. Such maintenance is not costly, butit is necessary to m;tintain the habitat.

Artificial wetlruids could be use<i o increase the types'of habitat availabl» inland ot natural estuarine wetlands 'onstrucrion of saline mud f! at s on disturbed upland habi-tat near intertidal wetlands would offer a nonttdal feed-

ing and resting ground for shorebirds, Sui:h habitat couldbe very valuable during high tides.

Perching Birds �0 sp.!Songbirds �7 sp.!

Barn swallowCliff swallowLoggerhead shrikeBushtitHouse wrenBewick's wrenWater pipitYellow-rurnped warblerLesser goldfinchHouse finchCommon yellowthroatYellow-breasted chatWestern meadowlarkRed-winged blackbirdBrown-headed cowbirdSong sparrowWhite-crowned sparrow

'I 8.632.69 34,72.32.34.72.32.3

11.646.59.3

25.620.92.3

55.84.7

IMPROVED METHODS FOR ASSESSING ECOSYSTEM DEVELOPMENT

CHAPTER 6

Improved Methods forAssessing Ecosystem

Development

6.1 MONITORING AND INDICATORS OFCONDITIONS THAT SUPPORT BIODIVERSITY

One overwhelming conclusion emerging fr oni pas rcs-tora iort efforts is thar it takes r»any year. for a site toevolve into a fully func i<ining, self-sustaining ecosys-tem, xylo system can claim o have done so. V»dually ev-ery site that ha» been monitored continues to chance S�15 years after the initial restoration work. Althoughchange is a characteristic of natural ecosystems, a con-structed wetland can be considered I unc ional I v equi va-lent to a natural we land only if the con strucred wetlandis changing primarily in response to environmental varia-tions, ra her than io shortcomings in be construction-for example, ransplanted cordgrass can expand its di»-tribution as suitable space is 'illeii v ia vegetativc expan-sion, but natural s ands cari also expand if prolongedflooding makes new areas hydrologic ally suitable.

Monitoring to distinguish developrncntaland na u-ral changes should be a niatter iif detecting directionalchanges. Expansiiin oi' cordgrass after prolonged Hood-ing may be followed by a period of shrinkage as the hy-drologic cause reverts to pre-Boo<i conditions. Yet somena ural events lead io directiorial change, Examples areaccelerated rise in sca level and subsidence which wouldallow inland expansion of cordgrass! and major sedi-mentation events v, hich ~ould cause shrinkage!.

Moniroring constructed wetlands o determinewhe her they have achieved functional equivalency withnatural sys ems or meet performance standards presentsseveral challenges, because lit le background inforrna-tion is available on the basic functions of ecosystems.The food webs have riot been well characterized or quan-tified. The distribu ions of most species are only gener-ally mapped. and the status of heir populatiiins isunquantified. The responses of even he dominant spe-cies of plants and animals o environmen al norms orextremes are, for the most part. unclear, The ef'fects ofrrrany invading exo ic species, such as the»ewly arrivedyellowfin goby a relatively large predator! and a 3apa-nese mussel now dominant in many subtidal areas ofSan Diego and Mission bays!. are mos ly unknown.

Vanous monitoring programs have been undertakenby PERL Table 6. I ! to track selec ed environmentalconditions and biota at San Elijo Lagoon. Los PenasquitosLagoon. Sv eetwater Marsh Na ional Wildlife Refuge which includes natural and constructed wetlands!, andTijuana Estuary. Funding $ ,00 y-$50, �0/year! is in-adequate o sample all ecosystein attributes often enoughto characterize changes in functioning. Although the mostimportant controlling factor for wetland ecosystenis ishydrology. no measurements are made of flow volumesor ve loci ies irom either the watershed or ocean sources,and there are no U.S. Geo!ogicai Survey stream gaugesimmediately ups ream of the estuary one just upstreamof Tijuana Estuary washed out in the 1980 Hood andhasnot been replacedl. Nor are water circulation patternsevaluated. 'I bc basic biological processes of the sys em i.e., primary pr iduc ivi y of vascular plants and algae,nitrogen fixation, decomposition, herbivory, andcarnivory! are not monitored, and the grow h rates ofanimal populations are not measured. Instead. surrogatesof functioning structural atiribu es of each individualsite! are evatua ed.

6.1.1 What Is Monitored and WhyAt each sire, the sampling program has been ailored toaccomplish the most appropria e wiirk for thc moneyavailable Table 6.2!. In some cases, additional monitor-ing work is carried out by agency personnel e.g., at SanElijo Lagoon. county staff sampled the birds and vegeta-tion!. Certain attrib» es are no management argets inall systems and hence are not satnpled e.g., cordgrass isof concern a Sweetv atcr Marsh and Tijuana Estuary;Coulter goldfieids are tracked at Los Penasquitos andSan Elijo Lagoon!.

Frequency of ineasurement differs for many of thefactors assessed, but in general water quality is measuredbiweekly or monthly, vege ation in September, salinityof marsh soil in April and September, and fishes and in-vertebrates on a quarterly basis. Special imerest specie~,such as resident birds and rare annua! plants. are censusedduring their reproductive periods {Belding's Savannahsparrows are censused during their territorial nesting


Table 8.1. Southern California Coastal Wetlands Monitored by Pacific Estuarine Research Laboratory

Wetland andTidal Condition

San Eiija L ago o nU s u el I y n o n t i d al

P rinci pal Manage me nt 0 ue stion sHow should the lagoon be managed? WhenShauld the mOuth be bulldOZed Openn

Fun din g Age ncyCouniy of San Diego

Las Penasquitos Lagoon FaundatianInonprofit!

How can biodiversity be susie-nedo How canresources be enhanced? Haw can fish kills beavoided~ When should the mouth bebulldozed open?

Los Penasquitos LagoonOften nontidal

hlalional Oceanic and AtmosphericAd mini st ratio n, S an ctu aries an dReserves Division

What are the dynamics of Tiluana Estuary?What are the effects of continuous sewageflows fram Tiluana and intermittent flows fromsewage spills" Will the estuary recoveronce sewage flows cease> How should the200-hectare restorai on pian beimplemented? How well wili the systemresp o nd to 'esto ration o

Tijuana EstuaryUsually tid al

Califarnia Department of Transportation How do the wetlands that were COnatruCted tamitigate damages to habilatS Of endangeredspecies compare with the nearby natu.alwetlands? When will lhe cOnalruoted wetlandshaVe COmplied With m fig atian require menteo

Sweeiwater MarshAlways tidal

season in spring; Coulrer goldfields when in flower!.The rationale for monitoring these various attributesand examples of data from these monitoring programshave been summarized elsewhere PERL l 990!. Thequestion is. are there simple, low-cost indicators ufwetland functions that mighl readily be used bynonexperts. or is this merely wishful thinking?

6.1.2 Indicators of Ecosystem FunctioningThis section covers the development of simple indica-tors ol ecosys em I'unc ion. whar migh be used to tes heir validity, and what more may he needed to go be-yond the single-species, single-habitat situation. Muchmore is yet to be done; no single indicator can ensurethar habitats remain capable of supporting thcbiodiversity of the region's coastal wetlands.

Table 8.2. Ecosystem Attributes Sampled Regularly at Four Southern California Coastal Wetlands

Attrtbure San E lifo Lagoon

Dne of tirst data 1986 1979f989 1986

X XX

s amp I e d in te r milt e n t1y

WaterquahiyLevels ofdissolved osygen,temperature, SdrnayprOfileaNutrienle rn lhe water column

FishSeines, orTaxis fore sotrc fehes

Benthc in vance ratesCore samples m channels

Marsh veg et anonOccurrence and coverCord 9 a heights and densityCordgrnss fofrn nitrogenCoultergofdfelds population

Marsh soilsSahnilyNutnents

BirdsBeoing's Savann& sparrows

Ability to support biodiversity. Situ hero Califor-nia wetlands are valued for their biodivcrsity. A princi-pal function that needs to he measured in both constructedand natural we land»s the ability to sustain native spe-C I '.!i.

Species hat make goin indicators of a v'etland'sabihty to support biodiversity have striing and specificlinks o one type of habita . When that type of habirat islost or damaged, the numbers decline, An argulnent ismade that residen endangered species are good indica-tors for how well ecosyS erne funCtinn in Sustainingbiodiversity because they are the first to decline whentheir habitars are lost or dainaged. Those endangeredspecies hat are animals and thar feed high in the trophicweb are also likely to be indicators of the condition of he whole ecosystem, though a contrary argumen couM

Loe Penaaqultoa Lagoon Sweetwater March Refuge Tlluena Eatuary

be made that specialist feeder» arc hetter indicators ofthe feeders' specific prey. For example. he v anderingskipper Pano< ur'r«r err«rrs! may be a good indicator ofits salt grass food base, or vice versa. because the butter-fly larvae feed only on salt grass.

The State of California recognizes 94 animal »peciesa» endangered or threatened with ex inc ion {Calif'omiaDepartment of Fish and {!ante !989!. 'I'hrce of these arcbird species: the light-footed clapper rail. Ucldtng'» Sa-vannah sparrow, and .he California least tern, The lirsttwo are resident species; the tern is migrat<!ry. An addi-tional endangered species is a hemiparasiric annual plantof the upper salt marsh; salt mar»h bird's beak. Manywetland-dependent species are rare and threatened withex inc ion; these include insects {c.g., tiger beetles, ge-nus Ci<i ride!!rr; wandering skipper!. Still others are con-sidered sensitive, such as the Coulter goldfieldsgosthertiu g{ahrara corrlreri!.

Monitoring designed to assess a region'.s ability tosupport biodiversity shouM track the populations of sen-si ive species. Richard Zembal ol' the U.S. Fish and Wild-life Service monitors clapper rails throughout SouthernCalifornia by using a network of volunteers. Counts aremade during the highest tides ot he year, when the birdsmove to the upper part of the marsh or are forced to be-come conspicuous by standing on float iii debris.

Canopy architecture. Canopy architecture is usedto assess the ability of vegetation in the lower and upperparts of the salt marsh to support endangeredbirds, Heigludistributions of cordgrass have been analyzed in relationro nesting of clapper rai!», and performance standardshave been developed {Zedler 1993, cf. sec ion 4,1.3!.Maximum heights and cover of gla»swort are used toassess the status of high-tide refuges for clapper raiils,and rnaxirnum heights ol'p<ckleweed are u»cd to assessthe abundance and distribu ion of perches for Bc!ding'sSavannah sparrows.

Tesing how well the evaluation of canopy archirec-rure might help in detertnining habitat o support thebiodiversity of the whole marsh i» a bigger project. It isnot recommended that canopy architecture be used a» asingle indicator of nesting habitat for clapper rails be-cause the correlation between tall cordgrass and nestingby rails does nol indicate that short cordgrass is the onlycritical limiting factor. For this reason, PERL also rnoni-tors the abundances of forage items {crabs and other in-vertebrates! and distributions of habitat types {arca andproximity oF high-tide refuges!.

Canopy architecture of cordgrass is likely to be use-fu! in evaluating habitat for predatory beetles, wliose pres-ence is essential for «ontrolling native scale insects Haliaspis sparrina! that can damage cordgrass {Boyerand Zedler 1996!. The adult beetles are not aquatic ani-rnals, Hence, they require high-tide refuges, such a» tallcordgrass stems <K. Wi!!iams, San Diego State Vniver-sity, personal communication!. An outbreak of scale in-

sect» occurred at one constructed marsh island hatlacked bo h tall cordgrass and beetles. 5 o standard» forheight distribu ions have been developed for this crih-cal carnivore. however.

Evaluations of canopy that can support nesting byBelding's Savannah sparrows have required a differentapproach. because pick!e«eed does not lend it»elf tomeasurements of height. Individual plants of this bu»hy.vegetatively reproducing perennial are hard to distin-guish. Pickleweed also gro<v » in a much wider range ofhabita s than cordgrass does, and it develops differentgrowth forms u~der various degrees of tidal influence.Maximum heights and branch strength are important,though, because the birds tend to perch on and defendthetr erritories from the highesl plants available { White1986, Powell 1993!. We measure heights of pick leweed,bu we have also experimented with remotely sensedvariables that indicate physiological stress. In the sec-tion on remote sensing, Phinn and Stow Section 6.4!describe the relationship between plant vigor and thenormalized difference vegetation index {NDVI!, whichis obtained by measuring the reflectance of near infra-red and red wavelengths. In our experimentalmesocosrns at Tijuana Estuary, growth of pickleweed{measured as branch elongation! was strong!y corre-lated with the NDVI. This is a promising indicator ofthe vigor of pickleweed,

Other indicators. Cordgrass and pickleweed arebul two of about two dozen vascular plant species thatarc impor ant in Southern California sah marshes, aridclapper rails and Belding 's Savannah sparrows are onlytwo of the thousands of species tha the salt marsh sup-ports. Thus, canopy architecture can be used to evalu-ate only one aspect of wha is needed to maintainbiodiver»ity. Beyond this initial effort, we need to de-termine how well the canopy information predicts habi-tat suitabili y I' or other species. Then, we need to workwith additional p!ant/animal communities and sprx:ies-spec itic dependencies,

Several measures of water quahty can be used toassess potential for suppon of flishes and invertebrates.lndicat<irs of stress include low concentrations of dis-solved oxygen at rhe bottom of the water column eariyin the day, warm water temperatures, lowered watersa!inities, and high biomass of phytoplankton andmacroa!gae. These conditions sometimes develop at LosPenasquitos Lagoon in Ia c summer if il is closed totidal action. These indicators lead us o recommendimmediate dredging of the inlet to restore tidal flowsand avoid a fish kill.

6.1.3 Testing IndicatorsSuggesting an indicator is the first step in evaluatingthe functioning of constructed habitat. Acceptance bythe scientific community is an important second step.lf the indicator is adopted by peer reviewers, the third

84 TIDAL WETI AND RE$TQRATION

step is o work closely with agencies that manage endan-gered species to test the cause-effect relationship betweenthe indicator and the functions it estimates. For heightdistributions of cordgrass, the variinions in canopy ar-chitecture and water levels at the nest s i e during the nest-ing season of clapper rails need to be related to nest fail-ure or success, and several marshes should be used asstudy sites. Because clapper rails are endangered, cau-tion would be required for such testing. Remo e record-ers of water level would need to be installed near thenesting sites, and a means of assessing floatation andinundation of nests wi hin plant canopies, wi hnut dis-turbing birds. would be required. If such tests supportedthe efficacy of the criteria, then nanagers would havegreater confidence in the indicator as a ineasurc of a suit-able nesting habitat.

The use o cnrdgrass heigh distributions to indicatenesting by clapper rails grew out of our long- erm I 2-year! moni oring prograin at Tijuana Estuary, which ledto an understanding of cordgrass dynaniics and provideda rich data base for comparing v el!-used clapper railhabitats with unused constructed cordgrass marshcs. Thcdata froin several cordgrass rnarshes a the SweetwaterMarsh National Wildlife Refuge, each of which has hada different histnry of use by clapper rails, made it pos-sible to compare marshes wi h grea er and lesser use byrails. Simultaneous s udy of clapper rail populations overmany years and in several of the regii>n's coastal wet-lands were carried ou by Zembal and Massey �983!;their insights into where nests are built and where andwhy nes s fail were critical in making the link with spe-cific canopy criteria. Finally. the availability of two ar-eas thai were constructed as habitat for light-fonted clap-per rails hut not yet used by rails! and planted withcordgrass at dii'feren dates �9 �, 19II5, and 1986!. alongwith funding for study �989 ff.h made it pnss>ble tncompare canopy characteristics of unused habi ats wi h hose of na ural, well-used sites for a period of years Zedler I 993!.

Siinple systems with few species and few managc-men issues may >nore readily use indicators. Certainlyon the Atlantic Coas there is a li>ng his <>ry i>f measur-ing cordgrass productivity to assess the importance ofmarshes to fisheries. In one case. the Great Sippewi sset Marsh in Massachusetts, cordgrass pi oduc i v ity has beenmonitored for 21 consecutive years as a major responsevariable to wastewater addition �. Teal, WHOI, personalcommunication!. In Southern California, measurementsof primary productivity were abandnned several yearsago because hey were bo h inadequate and too destruc-tive.

A single indicator is unlikeiy o suffice in areas witha wide variety of species and where the principal rnan-agement issue, that is, sustaining biodiversity, is so en-compassmg. However, the search for such indica ors andcriteria should continue.

6.2 IMPROVING METHODS OF ASSESSINGFISH POPULATIONS

1lu»>iusah Ruu

Quan i a ivcly sampling estuarine fish asseniblages ccnhe a difticul ask because of the diversi y ot rnicrohabi-

tats thai fish occupy v >thin these ecosys eins. A varietyof fish-sanipling gear has been usecl in salt marsh esin-aries, including throw traps, dn>p nc s. Ilu nes, hearntrawls. and seines. Of these, none is I X!% eff>cien incollec ing fish in any environnien . and all have prcsumeland known biases that vary depending on sampling con-di ions. operator proficiency, and f sh behavior. Onemeans of reducing this variable bias and iniproving Iheaccuracy i>f quaiiti a ivc fish assessmcnts is to estima efish populations within assemblages directly hy usingan assortment of mark-recap ure or removal me hod> Ricker 1 975, Seber 1982!.

Tidal creeks and channels arc thc most prevalent lisnhabita s in inos sall marsh estuaries in Southern Cali-fornia; some embayments arc present, but tn a Ies>erexten . The channel habi a ol these es uarics can be fur-ther ca egnrited into three generalized microhabiiahopen-water, epibenthic, and benthic areas. Although fisl>freely move ainong hese microhabita s. individual spe-ciess are generally adapted to a specific environment. Fo example, hc open-w uter inicrohabita is most of en oc-cupied by npsmeh and Cali lnmia k il li ish, the epiben bi areas by flatfishes e.g., California halibut and diamondturbot! and sculpins e.g., s aghorn sculpinh and h<benthic areas by the i>urn>wing guhiid species priina-rily arrow goby1. Obviously, no single fishing gear willprovide a high sanapling efficiency in all three micro-habitats, but seining has been the favored technique fo!sampling adult and juvcnilc fishes in Southern Califoenia es uaries PERL 1990!

ln the study repnrted here, catchabili y and samplingerror in popula ion estimates were calculated from theSep ember and December 1993 seine catch of f shes uTijuana Estuary. Thc fish assemblage of Tijuana Esiii-ary is sampled quar erly at .hree sites. as part of an on-going. long-term monitoring project. Evaluation of h<sampling gear Seine! prOvideS a basis fiir refining sa a-pl ing me hods. The specific objectives v ere to I ! co n-

IMPROVED METHODS FOR ASSESSING ECOSYSTEM OEVELOPMEh T

pare variOus meliiurei of catch ui piiiiihle populatinnindexes I with direc eilinialei ol liih popu liiiioni derivedby using a niaximurn-lihclih<i<i<i removal itiethod, �!quantify seine ca chahility «I'icv eral spec ici <if' fiih, and�! aisess he preciiion of ntei<f v,eigh eitirnatei de-rived for individual ipeciei l y i»easuring ii iubsamplcof fish vi. the entire catch.

6.2.1 Improving Ouantitative AssessmentFish were sampled in channel arcui <il Tijuuna Estuary ISO � 2 X! ni- each! enc1<iied by two 3-riiii! rneih blocknets. After the measured iainpling area wai enclose l.hsh were collected by using a l s.2-rn-h>ng. 2.2-m-widebag seine, also construe ed iif 3-mm nicsh nct ing. 8ein-ing was done from bank o bank. perpendicular to theflow of the water. Catch v as recorded separately for eachnl' three sei~e hauli; at iitei where ca ch lor any onespecies did not decreaie wi h successive hauLs. iv o ad-di iona! icine hauls were collected live total!. All col-lected fish v ere measured for to al length + I mmi andweight + 0.0l g!. Large tiih were rncasurcd in the iield;small fish were preserved uid ineaiured later in the labo-ratory.

Population abundance, bi<imaii. and catchahilitywere estimated hy using a removal meth<id maximumlikelihood estimator: Seber 1982, l3oh in et al. l989Iseparately for each species collected in the sampling area.Calculation of population es ima ci was facilitated byusing a mir roc ornputer sof ware appli cat ion spec ifi callydesigned for this purpose Kwak l992!, The removalpopula ion estimates were c<iniidered the most accura eestimate of the abundance of fiih p<ipulalions, and lessrigorous measures of ca ch iingle seine haul ca ch andsum of catch of three scinc hauli! werc conipared withthe removal estiinates. 1his cornparii<m allowed an ai-iessnient ot hc degree iif underes imation hat occur~ if

leis rigorous nieasures of fiih sampling are iubstituteda< populatio~ measurei or indexei.

Subsarnples of 20 fish were randomly ielected forweight measurementi ot'each specie~ a each ii e i I'morethan 2ff individuals were collected!. Mean wcighti cal-culated fr<im the 20-fish subsamples werc compared withthe corresponding mean weights obtained by weighingall fish collected for thai .ipecici and site. 'I'hi i compari-son evaluated the degree of preciiion lost by weighingonly a subsarnple of the catch vs. the cn irc catch,

6.2.2 Better Estimates Through StatisticsLess rigorous measures of fish catch werc substantiallylov er than the corresponding removal population esti-mates. The catch from a single seine haul wai, <m theaverage, only 23.4% of the removal estima e, and lhesummed catch of three seine hauls wai 5 l.3 ~r of the es-

timate, bu individual comparison~ varied widely Fig.6. I !. Thus. fi sh biologists who collec only a single seinehaul in a sampling area are grossly underestimating popu-

100

75

fv 50era.

25

3-samplesum

Firstsample

Removalestimate

Figure 6.1 Comparison of less ngorous sampling catches first seinehaul sample and sum ol three seine haul samples! to the correspond-ing removal population estimate for each species and site. 0ata aremean i range, Al 6! percent companson of less rigorous caich tothe removal estim ale. assuming thai the removal estimate is the bestrepresentation <00%! of the population.

laiions and most likely are collecting only about one-quarter nf the fish preienl. If three ieine hauls are col-lected, about one-half of the fiih present wiH be sampled.Therefore, it is important o express the results of fishcollections obtained by using lesi rigorous samplingmethods in terms of catch per unit effort or a species listrather rhan lo erroneously present those data a.i estimatesof population density or biomass. These results stronglysupport eitimating popula ions direc ly, by uiing eithera removal or a mark-recapture method, in aiiessmentsof fish asseinblages. Furthermore. for all quantitativesampling, an encloied area should be used ro preventescape o ' lish during sanipling and to add an area com-p<ment so that population estimatei can be converted todensity e.g., number of fish per square meter!.

Average catchability for hc three most common spe-cies of fish in Tijuana Estuary opsmelt, arrow goby,and California kiHifish! v as between 0.40 and 0.50 of ainaximum possible value of .0 Table 6.3!. Meancatchability <if the slaghom iculpin was higher �,55!,and that for diamond turbot v as lower � l2!. Fish thatwere rarely cap ured had catchabili ies of either 1.00 orzero; thar is. rare fish are cithcr all caught ca chability =L00! or all escape catchability = 0!. The wide i ariationin catchability within and ainong species further supportsusing s a iitical melh<ids to estimate populations. Therelative abundances of ipeciei in the seine catch may bemore indica ive ol' heir catchahi lity when a seine is usedthan of their actual occurrence in the sampling area. Popu-lation cs imates calculated separa ely for each specieswill correct for such variable gear bias.

The mean absolute difference between populationmean weights calculated on the basis of a 20-fishsubsample vs. weighing all fish collected v as 9.6%.

Sfi TIDAL WETLAND RESTORAT ON

Table 6.3, Calchab!! ties of Fish CollectedDecember 1993

No.SaSpecies Sites

Topsmelt Attrerinops afli«slCalifornia killitish Fundulus parviprnnus!Arrow gaby Clevelandia ios!Stag horn scu lp in Le pto co !us arma us!Diamond turbot Hypsppsetta guttulata!Gray smoothhcund tv us eius caliyernicvs!Longiaw mudsucker Gilfichthys mirabdrs!Op al e ye Gi re l la nig ricans!Bay pipefish Syngnathus leptorhynchus!

lVo e: Maximum catchability = 1.00.

Considering the cffor that can be reduced when tish catchfor an individual species may be nore than !,000 indi-vidualss, a leis 1han ! 0% loii in preciiiori can be jus if edfor estin1ating fish biomass by measuring a subsampleof 20 indi v i dual s,

6.2.3 A Proposed Standard for EstuarinePopulationsA three-sample reiiioval popula ion estimate maximum!ike!ihood method!, in which a bag seine is used in anarea confined by block nets. and lengths and weights of20 indiviiiuali per species are ineasured, i» proposed aia practical standard to quan ify es uarine fish popu!ationiin Southern California. The continuation of this studywill increase sample iizes and nay include addi iona!species to add more certain y to the interpre ation of thesefindingi,

6.3 ANALYSIS OF THE FOOD NfEB AND FISH-SUPPORT FUNCTIONS

Thomas J. K~ at

Two basic questions about hc functioning of wetlandecosystemi are which primary producers provide the bulkof the organic ruat cr hat fuels the food web, and whethergrazer- or detritat-based food chains are more prevalent.Ecologisti have begun o examine ra ios of naturallyoccurring stable iio opes of carbon, nitrogen. and sulfurto determine sources and sinks iif materials Peterson andFry !987!. Studies of s able isotopei in food webi can

in T/juana Estuary in Septe rube r and

otmp le d Me an S E R ange

0.1 8 � 0.730.07 � 0.65

0 � 1 000 32-1.00

0-0.24

0.450,410.460.550.121.001,001.001.00

0.270.180.180.220.1 2

indicate iourcei of organic rnatter .hat feed consumersand can provide inforiii;i ion on trophic relatiiinihipswithin ecosys erni. Measurements of stable isotopes areparticularly useful in s udiei ol ei uarine food webi be-cauie these systems are though o be based on detritu s.and the origin of detrital material is difficult to de er-mine by other ineans.

Aniinali and their diets are similar in iiii opic com-poii ion for carbon, sulfur, anil nitrogen. Isotopic ratios see formulas in next section! for theie lhree elemen schange slightly bu predic ably when the clemenLi areassimilated Peterson and Fry ! 9g7!. Thus. unique "sig-nuturei" are formed by cor»bina ioni of mul iple stableisotope ra iiii. and hcse signa ores can generally betraced hrough the food web with some slight changeaniong trophic !evc!i. !n this nianner, hc ultimate sourceol' food support for variiiui consumers especially eco-logically important fish and hirdi! can he determined il'the signaturei of potential sources are iuflicienlly dis- inc . Infortnation «n the trnphic level ofconsurneri canalso be ascertained by exaniinirig the degree of frac-tiona ion in nitrogen isotope ratios among consumeri.

6.3.1 Technical BackgroundI may be necessary to contract wil.h an outside labo-

ratory io do itah!c isotope analyses becauie of theexpense required to iei up and maintain the requiredinstruments, Although no published lis ii available, anumber ot laboratories in he United States and Canadaspecia!ize in stable isotopes and will do analyses for afee. Ratios of stable isotopes of carbon, nitrogen. andsulfur in organic materials collected in Southern Cali-fornia salt marshes werc dc crmincd by Coastal Sci-ence Laboratories i» Austin. Texas. Each sample wascomplete!y converted to a gas by combustion and sepa-rated into pure gases CO2, s�, and SO2!. Each puregai wai analyzed by using an isotope ratio mais spec-trometer, and the i.iohipic composition was quantifiedrelative to a standard reference material. Standards werecarbon in the PeeDee timestonc. nitrogen gas in air, andsulfur from the Caf yon Diablo meteorite, Results foreach element were expressed ai parts per thousand dif-ferences from the corresponding standard o7!:

!MPAOVED METHODS FOR ASSESS NG ECOSYSTEM DEVELOPMENT 87

e!X = [ Rs<rrrlpf<".Rslu»<y«rrrcsponding au<i �f ISC~I2C 1 Ntl4N. cir -~4S/1 S. The <J valuesinclude a measure of both heavy,ind ligh isotopes,whereby increases in 8deno e rcluiive iricrcases in theamoun of heavy isotope.

6.3.2 Role of Detritus in Atlantic CoastWetlands

Early studies of stable isotopes in tidal creeks nf a Geor-gia salt marsh sh<iwed that he de ritus in tha sys emwas isutopically nore similar o ph>t<iplanktori than tocordgrass Haines 1977!, and subsequcn research sug-gested that consumers were being supported, at lcas inpart, by phy oplankton Ka nes and Montaguc 1979!.These findings hrough into question hc hing s aiidingdogma of a vascular plan source of de ri us that sup-poned salt marsh food wehs. Inves ig;i nrs have sincereported various relative influences of vascular plantsand algae on the salt niarsh food weh c.g., Hughes andSherr 19113, dackson et al. 1 986, Sullivan «nd Moncreiff1990!.

Mos of these ec<isystem-level s udies have beendone in Atlantic coastal marshes. no similar studies havebeen done in Sou hem California salt rnarshes. Relativeto A Jan ic sal marshes. Southern Califoinia es uariesare distinct in topography, hydrology. vege a ion, andfauna and in anthropogenic iiifluences on the eiiv inin-rnen and i s biota Zedler 1982!. Thus, the relative im-portance of vascular plants and algae as an ul imate foodsource tor invertebrate, fish. and bird consumers remainsunknown for Southern California sah marshes. The find-ing Zedier 198 !! that algal mats can be as pr<xiuctiveas he vascular plant overstory in a Snuthem Californiasal marsh casts furi.her doub that thc dogma of avascular plant, detritus-based food web applies <i theseecosystems. Given the grea amount of' effort and cos allocated in a te np s to restore and enhance estuarinehabitat in Southern Cali 'ornia, the origin of the foodweb in these systems is vi al information tha will berequired o understand ecosystem functioning and guiderestoratioii efforts.

6.3.3 Role of Southern California SaltMarshes in Supporting FishOngoing studies at PERL are the firs contprehensivea teinpt to determine hc source of foods for consumersin Southern California coas al marshes. The four pri-mary goals of the research are tn I ! determine thc rela-tive importance of vascular plants and algae as he baseof he estuarine food web that supports higher roph<clevels, including fish and hirds; �! assess the influencof sewage inflows on he fooci web; �! determine prin-cipal foods of estuarine fishes. and �! gain i< sigh on rophic relationships among consumers in sal niarsherc

By combining stable iso ope studies with direct assess-rnen of fish food habits, both ultimate and direc fish-support func ions can be de ermined. Successfulachievement of these objectives will provide informa-tion useful in managing, restoring, and understanding theecology of Southern California sal marshes.

Data and organic ina erials were collected in March-April and August-September f 994 from four sites within he northern ann of Tijuana Estuary and from wo sitesin San Dieguito Lagoon. AI hough both salt marshes havebeen altered and degraded by human activi ies, TijuanaEstuary re nains less disturbed and more ecologicallyfunctional than San Dieguit<i Lagoon. Comparing find-ings froin a fully idal, functioning system v ith founding~from one more degraded will add insigh to be applied inres oi ation planning. Sewage-derived organic matter wascollected direc. ly from a sewage collect<on facili y in thecity of Tijuana and from a canyon on the southern edgeof Tijuana Estuary that receives raw effluent regularly,

Sainples analyzed for stable-isotope composition in-c! uded both human influences sewage-derived iirganicrnatter! and sal marsh primary producers as potentialsources of' he organic matter that forms thc base of theestuarine food web. Primary producers were collec cdfrom tidal creeks and both high- and low-marsh habitatsand included four genera of rnacroalgae, two genera ofcyanobacteria, and four species of salt marsh vascularp! ants. De ritus in the water column was assessed directlyas a cri ical link in the food web that nakcs immediatelyavailable the energy and nutrienLs from the pritnary pro-ducers or sewage! o the consumer~. Sampling inc! uded14 inver cbra e, 7 fish, and 2 wetland resident bird spe-cies o represent primary and secondary consuiners Table6.4!. Although allspecics c<intributc ecolngically o theestuarine food web, several have nore obvinus value tohumans. Tv <i fishes of commercial and recreational im-portance. Calif<irni a halibut and diamond urbot, and theendangered bird, he light-fooled clapper rail, werc in-cluded in the study,

Selected findings from this study Kwak and Zedler,in review! include the follov ing:

~ Isotope ratios of producer groups were statisticallydifferen ia ed mos clearly b> the carbon isntope.then by sulfur, and least clearly by nitrogen. Con-sidering the hree isotopes collectively further dis-tinguished the producers. This was an importan first step in clarifying the base of the food web.

BS TIDAL WETLAND R ESTO RAT IOII

Tattt< ~ 6.4. Summary of Organic Materials Collected fromTtluana Estuary and San Dlegulto Lagoon for Deterrslninglguttlpie Stable Isotope Ratios of Cart>on, Nitrogen, andSulfur

No. ofTax ~

ffo. ofSamples

No. ofBitesMeter< ~ I

Bet<in>'yNANA244

1472

TlluenaParticulate organic stat<elSewage-denved organic rnatterCyano >act en aMac roatg aeVascular plantsInveneo<atesFis hBirds

4 2 2 4 4 3 3NA6

4 211261416 4

Total 75San O<egutte Lagoon

Particulate organic matter NAMac roe>gee 3Vascular plants 1tnt has 3Total

4< 1Loca<loneNANA

2 4 414 7 2

Particulate organs: molterSenege4<erived organic matterCyano>>actenaMac roatg aeVascular plantsIn vert et>rat esFishesBirds

6 2 2 7 6 3 5a<A

6 4 216221425 49333Total

~ The dlitributi<>n of i.iotope ra ioi of fish in SanDieguito Lago<in wai significantly more tightlyclustered leis variance! than that of lish in TijuanaFstuary. suggesting that a more complex food webeXists at Tijuana Fituary.

~ Fish isotopic iignatures v ere iignificantly difiere-ntt between wetlandi f' or carbon, but not I'or nitro-

gen or sulfur. which may be related to the relativescarcity of C4 plants a San Dieguito Lagoon.

~ Reiuhs of ac!usteranalysi~ indicatednatural group-ings of isotope ratios of broad producer and con-sumer groups ha «ppear to be related to habit~ type and salt tnarsh elevation.Trophic enrichment of the nitrogen isotope sug-gested hat at least four trophic levels exist in theTijuana Estuary food web and that the light-footedclapper rail was the highes -level coniumer amongthOse salnpled.

In general, our results indicate that the food v eb ofSouthern California salt rnarshes is more complex thanthose of Atlantic and Gulf of Mexico coastal sites wheresimilar analyses have been done. The isotopic composi-tion of major consumers relative to that of producers sug-gests that maCroagga, cyanobacteri a, and vaSCular plantifSparrir<a! all contribu e to thc food-web hase. It alsoappears that sewage inflows to Tijuafta Estuary providea minimal contribution, if any, to the estuarine food web.

Relative contributions of' producers and sewage tothe food web in these systemi cannot be defined pre-

ciscly hect>use of thc nun>bet i>l' po ential sourcei l,i.e.,quantitative mix ittg»«>deli c;innot be dcvch>ped!. Thisdiff>col y reveali a limitation in uppiying stable iso opetechniques to fo<id-wch itudiei ot ial marsh ecoiystemsthat muy he par icular to Southern California systems.Southern Calitornia c<>ai al t<iarihei arc confined to nar-row itrear» <iulleti ali>n thc coastlhie that are usuallyiurr<iunded hy itecp. rugged iipogruphy Zedlcr I'9 I'i.This phyiiographtc it. ting ii in marked contrast to thebroad, tlat coaita! plains <if he Ailarnic and Gulf coaststhat form exparliive ei iiarine systems. Intertidal ialtmarSI>e» alOng the Atlanttc and Gull c<vai i may enCOltl-pass many ki!<>mc eri anspecific vegetation e.g... Ilackney and HaineiI98ph whcr«ai in S<>uthern Calit'omia iystems. such asthose we itudied, liigh-and low-marsh habitats are muchm<>re ipat ially proximate and <nay be ieparated only bymeters.

The ipatial prox imiiy ol habi a s and associated veg-etation in Sou herii C;ililornia marihes likely inl'luencedthe hnding of niultiplc iources con ributing to a com-plex food wcb. Thus. more potential sources of organicmif cr should be considered in f<iod-wcb itudiei of thesesystems, relative urcei areadded to analyses, however, it becomes incr<.asingly dif-ficult I<> diitinguiih patterns among produceri and be- ween producers and cOnsunters, Incorporating additionaliii>topcs into a itudy could improve he ability lo nakedistinctioni, hut the point remains hat the technique havlimitations in complex ecosystems.

Our findings have intpoftant iniplicationi for v,el-land managefncnt. Because no single habitat in theestuarine ecosystem can be excluded lci iuppor ing pro-ducers that contribute o the food web, all intcrtida! hahi-tats tidal creeki, salt marshcs, pools, sal pans! shouldbe protected. restored, and inanaged when the objecuyeii to develop or enhance fiih or bird habitat in SouthernCalifO nia Coalualmarihes. We antiCipate that our resu!tvwill be uicd in future iiegotiations about rni igation plansfor areas dcsigt>ed to replace habitat that supported fish.lt is reasonable to conclude that salt marsh habitats con-trtbute to fish support; hence, reit<ira i<in of bothchannel and salt marsh habitat could bc considered mili-

ga ion for lost fish habitat.

6.4 USE OF REMOTE SENSING TO MONITORPROPERTIES OF VEGETATION

.'st<rut> Phittt> at><l ffr>ttelut .'itrin

Remote sensing of terrestrial vegetation is baied on theprinciple hat the amount of electromagnetic radiationretlected or emitted from plants ii determined by the I<7eof plant and the plant's biophysical characteristics fe.g.,

IMPROyED METHODS FOR ASSESS N ECOSYSTEM DEYELPPlyENT 8g

heigh , horizontal and vcr ical le<it areas. hioniass.chemical composition, and product iviiy l. There arc dif-ferences in the amount of e lectroniagnctic radiation fromthe sun reflected in di ffercnr v 'avelcng the from wetlandplants and soils Fig. 6. !. Rcmiitcly sensed data c,g.,aenal photographs, sate lli e iinage». da ;i c<!! Iected v, ithhand-held radiometers! tiavc been used cx ensively odelineate wetland are is and i<i map the c<im pox it i<in oftheir communities. These data are el i<i useful for niea-

suring and mapping thc bi<iphysical «haracterisrics ofv:etland areas. Remote sensing has several advantagesover field sampling approaches. It is n<mintrusivc, someasurements can be made in inaccessible areas, and itprovides repcatahle coverage <in micro to regionalscales. Remote sensing does not replace field sanipling,but it docs provide syn<ip ic coverage to guide ecologi-cal work.

04o

0.35

eau<tlVC 0.2$

~ <t20

Z ais

Q.i o

i ps

O.oo R I < ' cD r c> <c <v tl 4l ro o

Wavelength

Figure 62 Representative samples oi reflectance spectra rom saltmarsh habitats using a hand-held spectrometer.

Historically, the development of remote-sensing ap-plications for napping and monitoring coastal v,etlandshas centered on the extensive wetlands of the Gulf andAtlantic coasts. Surnmarics of research relating remotelysensed data to characteristics of wetland vegeta ion havebeen published Carter 1978. Hardisky' cl al. 1986, andCrross et al. 1989!.

The tools and techniques used iri we land applica-lions field radiorneters, multi-spectral scanners, anddigital videography! are explained here f<ir monitoringvegetation m restored coastal wetlands. Most researchon use of remote sensing in we lands has focused on es-tablishing and testing relationships bc ween he spectralreflec ance and biophysical characteristics of wetlandvegetation for relatively large areas of monotypic,

undisturibed wetlands, ln our experience and in our review of the literature, we have not 1'ound any applica-tions of multispectral, digital remote sensing formonitoring restored wetlands. Also, Ii tie information isavailable on remote sensing of the smaller, species-rich,and highly disturbed Pacif c Coas wetlands. Monitor-ing disturbance and restoration in these areas requiresin form anon on the compo si ion, srructure, and o her char-ac cristics ol vege ation a specific spatial and temporalscales Kusler and Kentula l 9h9l, Remote-sensing tech-niques can be used to provide hese data, as shown hystudies on the East Coast. Developing and using thesetechniques and data should improve ecological monitor-ing and adaptive manageinent in wetlands.

ln the sections that follou. we focus on three poten-tial applicattoris of retnote-sensing techniques for wet-lands moni onng restoration of wetlands:

I . De ermining and mapping the areal extent of indi-vidual species and assemblages

2. Assessing the structure of he vegeta ion or land-scape horizontal and vertical!

3. Assessing the condi ion of'ihc vegetationSev eral case studies v ill illustrate our expenence sv ith

these techniques in Southern California.

6.4.1 ApplicationsUse of remote-sensing techniques helps establish eco-logical indicators of he ype and condition ot vegetationin wetland ccosysterns tllalvorson 1991, 1oehle 1991!,Previous use of re<no c sensing in monitoring East andGulf coast wetlands has been at local to regional spatialscales I-INK! km-! in rnonotypic, relatively undis-2

turhed wetlands. In contrast, applications for wetlandsrestoration and monit<iring in Southern Califonua requiredata on micro ro local scales <I � 100 ha! because hewetlands are small often fragrnentedl and heterogeneousin species composition, Techniques developed <in the Eastand Gulf coasts had to be refined before they could beused on the Wes Cons .

Before reniote sensing is used to characterize wet-lands. careful consideration should be given to the spa-tial and temporal scales being examined as well as theintormation required o make management decisions,Suitable da a and techniques for analysis are then se-lected. It is neces.sary to determine if he da a requiredsa isfy the three basic types of information at a suitablescale to be provided by remotely sensed data Table 6.5.columns I and nh

The rest of his section outlines available data andtechniques to address each of the three basic informa-tion c ate gones.

6.4.2 Mapping the Areal Extent of Species antiAssemblagesSpatial and spectral resoltrtjon. A m~cro to local scales I m- to I km-l, remotely sensed data can be used o2 . n

Table 6,5. Infor<nelion Requlreraents and Suitable Dale and Analysis Techniques for Monitoring wetlands Restoration

Spatial Te m pe ref!Scales Analysis Techniques

Manual delinealio nDataS pacific f e eture 8

Wetland boundanesVegetatren Species composrf<onHabitat co moo sit<on

Information RequiredAred extent and location ofmarsh vegetation spaces

Daia from airborne video orscanner systems

Micro io legiohalp-10 years!

If patch > pixel size W per-pixel classifier+ ancillary data~ knowledge-based classaier

Scanned color infraredphotographs

If patch x pixe I size w mixturemodel approach

High-resolution sa!e llifeimages

Ancillary digital data e.g,topography!

Exp lorato <y spatial dataafi al ye Is

Unprocessed image sMicro to local�-10 yearS!

TypeSize, Shape, COmpleXay,co no ectivity, dispersionEdgesDiversity

Vegetalion patchch<sactensiics landscapesfivciure! Calibrated and dassif isd

If!lag o s Landscape structure metrics

Existing we liard boundaryorvegetabon maps

Field radio met ry andspectroscopy

Spectral radiancemeasure me nts in arrow o rbroad band!

Micro io regionalimonth � 1 tiye arel

i<d!vidual plant!canopy ho nzo nialand vertical dimensionsBiomassNel pnmary produciiwiyProcesses photosyn <basis,tran spiratio <i!S !re asTrace gas flux

V age<ation siruciure andcoridni on

Establish relationshipsbetween spectralindexesand biophysical paramere rs

Corrected images

Biophysical paramete rsasso mal ed with spectra orimages

Scale up radiometerrelationships to pixels

deli<1<,"it<.' p;t Ches or'i the gri!UIEd I'epic!i<.'nting 'the esteritiil it purlicular in;irih lype, u churactcriilic aiiemhlage<if ipCClei, at> are,> <if Strciscd plums. <ir he eX enl Of awetland. Iii <irdcr to determine the upprripriate type ofihi it un<'I a!E<ilytiC teChnique f<ir delilnit ing theiie pulChes.ievcral t'itc <in i»uil hc coniidercd. Theie include theiire <if lhe regi<nl of intercit CXtent!. he CharaC <.'riStiCical» <it the pa chci iil vegetation pure i andi or wet-land boundariei!. tcinporal variahitily of these palchei,u»d ihe type Ol In Ormul ain required hiiundarV h!cat inn,ureai, hiiiphyiical churaC eriitiei!.

For dpi in! iling wetland boundaries anil mapping theareal exfcnl und diitrihul ion <if' varioUs wetland pl<tntipecics. generally ipeaking. Ihe spatial resolution of hed<ilu ihould he nii greater than half the size of the imall-eil feature to be defined, For example, if the minimumwidth of .itands ol' cor<fgraii ii 2.0 tn, an image withpicture elements pixels! leis lhan ],0 m would usuallyhe necesiary to delimit theie areai. Sin!i turfy. the spec-tral properties specific wavelengths of ~ensed electro-magnetic radiationl of he <lata inHuence rhe amount ofinformat<on that can be extracted about the condition andstructure of the vegetation. Some wavetengthi are moreSeniilive O ahxnrp IOn hy pigrnen S in vegetatiOn COn-trolled by leaf chemiilry!. whereas olheri are more sen-iilive ro scattering by leaf structure and moisture con-rent. Spec rat re~olution increases in the following orderof types of remote sens!ng data; color infrared aerial pho-tographs, multispeclral images <20 bands!, and imag-

ing spectrometer dara >f00 bundi!. The greater nurn-ber ol' handi p<!tenlially allOWs InOre infOrmatiOn Onicene characleriit ici to he esluhl!shed,

fnl'rared,lnd color infrared aerial photography aticalei trorn I: t. X� to I:1 !, XX! have been used suc-ceisf'ully ro delincuie wetland houndaric» and to deter-mine he ex cnr and condition nt' various spec iei of marshvegela!i<in Anderson and Wobhcr 1973!. These tech-niques are relatively cost-c! ficient and are oullined in anumber of lnrroduc ory leX i on rcrnote SenSing.

ln contrast, nlultiipectral or hypcrspectral digitalimage data store multiple spec ral hrighnless values perpixel, a f'omlu amenable to cornpuur procesSing. Animage can be considered a number of gridi. and eachgrid layer contains brightness valuei for a specificwaveband. The hrigh ness value in each pixel is a ftrnc-rion ol' the number <>I different vegetation types in thepixel and their relative abundance, structure, and condi-tion, Brightness valuei can be converted to physicalquantities such as spectral radiance or ipectral reflec-tance when suitable calibratiori data exist,

Image classification. Automated processing of im-age data with comrncrcially availahle software packages ERDAS, PCI. ER-IVlAPPER! makes it possible to de-tect groupings of pixels with silnilar brightness valuesin all bands. This process ii referred ro as image classi-fication and usei multivariate sta istical clusteringalgorithms ro delimit groups of pixels with similar val-ues in each spectral band. The analyst determines the

MPRPVEP METHODS FOR ASSESS htG ECOSYSTEM DEVEI.OPMENT 91

number of classes and suitable ranges ot pixel values ineach image band and iiften provides "traii»ng da u" withstatistics on the required classes These groupings areassumed lo represen pit ches ol a speci f'ic type or condi-tion of vegetation. Field veri fica ion is also required tocheck this. Either the raw image dara or special cornbi-nations of image bands can bc used in image classifica-tion. Specific transforms or combinalions of bands suchas he 'ADVI and principal cornponems analyses producepixel values that are more highly rclatecl o the charac-teristics of thc structure biomass! anil conditi or of veg-etation than the raw bands arc Jackson 1 986!. The xIDVIis an index that ranges trom � 1 o + I. "Healthy," densevegeta ion has high ixIDVI values. and stressed or deadvegeta ion usually has values near or below 0.

For applications in which rhe area of in crest e.g.,patches consisting of unifortn asscniblages of vegeta-tion! is larger than the pixel size, per-pixelclassificationtechniques are used. These algorithms usc niultivariateclustering routines o detect groups of pixels with simi-lar spectral brightness values. These clusters or spectralclasses are assumed to represent areas of distinct typesof vegetative cover on the griiund. If ancillary data areavailable for the restoration site. tliese can be combinedvvith rhe retnotely sensed data in a moditieil classifica-tion routine. For exainple, if inforination on the topog-raphy and hydrology are in digital 1'inmat and compa -ible as raster or vector-based files! v il.h the imagery.rhey can be used to help in the classification. The spec-tral brightness values for each pixel are assessed to de-termine he vegetatiiin class the pixel is likely to fallwithin. and this allix:ation is checked against the eleva-tion range and distance from channel for hat class. Mostimage-processing sys ems have thc capability to irnple-ment these schemes v ilh coinbined geographic infor-ina ion system modules.

For applications in which the area ot inrerest issmaller than thc pixel size. subpixcl analysis techniquesare used mixture inodcls!. Each pixel 's spectral bright-ness values are assumed to result from a certain combi-nation of reflectance values produced by each object andbackground in lhe pixel. If the spectral reflectance val-ues for each different type ofohject are known from pre-vious hanil-held radiome ric or spectrometric work, thepercentage of each pixel covered by eacli object typecan be estimated. Useful explanations of the rnixrure-modeling approach have been published 92.Istin er al.l986, Adams et al. 1993!,

6A.3 Assessing the Structure of Vegetation OrLandscapeThe purpose of examining the structure of the landscapein res ored wetlands is usually to describe preferablyquantify! the horizontal and vertical variation in assern-blages of various plant species. Once he characteristicstructures are established. they can be related ro or used

as ecological indicators for the status of the wetlandecosystem. Information is provided for evaluating thecondition or functional capability of the wetland byquantifying the struc ure of patches of vegeta ion inwetlands te.g., detecting patches of specific types ofvegetation and determining their areal extent, density,shape, and ci>nnectednesx o other types of vegetation!,Depending on the rype ot information required. woapproaches can bc used with remotely sensed data toestabli sh descripti on s of landscape struc ure.

First, the most common form and size of pa ches ofvegetation, characteristic length scales of landscape fea-tures, or the overall degree of spatial variance in typesof land cover types can be determined by exploratoryspatial data analysis. These techniques can be appliedto individual spectral band images or to transformedimages of airborne mullispecttal iinagery. In order toestablish descripti ve information on landscape struc-ture, such as the range of commonly occurring parchsizes. spatial statistical measures such as variance win-dows of di Terent sizes, semi-variograms, correlograms.and other s ructure functions can be applied. Thesemeasures have primarily been used with imagery innonwetland areas Woodcock et al. I 988a. 19ggb;Siinrnons et al. 1992! and have been discussed exten-sivelyy in terms of their potential application to ecologi-cal patterns Turner and Gardner 1991, Rossi et al. 1992,S irnrnons et al. 19921.

The seciind approach generates more specific in-formation on landscape structure. "Landscape metrics"can be applied to classified images see previous sec-tinn ! or to iligitized maps of types of wetland land cover.Landscape metrics are indexes that summarize the spa-tial characteristics for one particular pa ch or for a col-lec ion of patches of one type of vegetation. Thesemetrics, which are often used by researchers in land-scape ecoliigy. can provide insight into the pr cesses orconditions that prixluce a particular landscape panem O'Ncill et al. 1988, Tamer 1989. Turner and Gardner1991!. Several patch characterisrics can be quantifiedby using FRA STATS McGarigal and hfarks 1994!,a public-domain software package Table 6,6!. This andsimilar programs require input in either pixel- grid! orvector-based polygonal! representations ol maps ofvegetari on type. In both cases. remotely sensed da a canbe classified to delimit polygons of vegetation type thatcan then be analyzed by using landscape metrics. Eachlandscape metric shou!d be fully understrrod before itis applied to data to make an interpretation. For example.does it represent the cornposilhin or the configurationof the landscape, or both.' %hat aspect of configura-tion.' Which scale is spa ially explicit? These questionsand others should he asked o determine if the Iand-scupe metric represents the landscape structure in anecologically meaningful vsav and can be used to assessres oratron. The metric should provide information on

Table 6.6. Landscape Metrics Computed in FRAGSTATS

Scale

Area metncsMetricAreaLandscape similarity indexClass areaPercentage ol landscapeTotal landscape areaLargest patch index

Palch densify, size, and vanabilitymetncs

Numb e f of patchesPatch densityMean patch sizePatch size standard deviation and coe'ficient ofvenation

Shape rneincs Shape indexFractai dimensionLandscape shape indexArea-weighted mean shape indexDouble log and mean patch 'racial dimensionArea-weighted mean patch fractal dimension

Core area inc tncs Core area, number of core areasCore area index, percentage of landscapoCore areadensityMean core area per patchPatch core area standard deviation and coefficient ofvan at Io n

Mean area per disjunct coreDisfunct core area standard deviation and co efhcie et ofvenation

Total and mean care area indices

Nearest neighbor distanceProximity indexMean proximity indexNearesi neighbor standard deviation and coefficient ofvari at le ii

Nearest neighbor me ines

Shannon'sand Simpson's diversify indexesPatch nchnessPatch nchness densityRelahve patch nchnessShannon s and Simpson's evenness indexModified Simpson's diversity and evenness indexInterspersion and luxtaposiiion indexContagion index

Souice: McGangal and Marks 1994

vegetation or habitat conditions an ecological indicator!that «re related lo the restoration goals and performancecriteria.

6.4.4 Assesslrtg the Condition of VegetationMost work in which remote-sensing echniques were usedto assess the condition of wetland vegetation were basedon plot-scale O.l-l.O m ! relationships between hand-held spectral radiometer or spectrometer measurementsand sirnuhaneous measurements of biophysical proper-ties e.g., aboveground biomass, stern lengths, and leafarea indexes!. Two approaches are commonly used. cm-piricaliy derived relationship~ and deterrninistically basedmodels. Both approaches involve two stage~. First, theproperties of the vegetation structure, condition, radia-tion transfer! that control its spectral ref!ectance pniper-ties are determined, Second, a deterministic model or


Dive rsay, contag ion, and interspersioninetncs

empiricaily derived relationship is used to relare one orseveral of the measured biophysical parameters of the veg-eta ion to spectral rneasureme»ts c.g., Asrar l989. Grosser al, l 989!. The model or relationship can be inverted andthe measured spectral reflectance values used to infer bio-physical parameters for the vegetation a that site.

Hand-held radiometry. The instruments used mostoften to obtain ground nicasurements of spectra of we -land vegetation are spectral radiometers � � 8 broadwavebands! or field spectrometers X! narrow bandsi.Descriptions of these instrurncnts' operation, applications.and differcm models have been published Hilton 1 98 ii.kadiomerers and spectrometers record the strength of ra-diation reflected from surface features or incident frontthe sun and atmosphere from within an area determinedby the instrument's field ot' view, Filters are used to linurthe range of' wavelengths sensed. A spectrometer senses

IMPROVED METHODS FOR ASSESSING ECOSYSTEM DEVEI OPMENT

in more and nanower rarigcs <it' v avcleii tlii than a r idi-orne1cr does.

Once the spec ral bands and required hiophysicalparameters have been dererrnincd, a iuitiiblc spatial andtemporal sampling schenie cail bc dciigned. Spa ially,the sampling iicherne sh<iul<t be wirhiii pure standi ot'aspecific communi y of vege a i<in for ivliich a relation-ihip nr model is being <developed and should repreientthe rarige of'srructural uid spectral variahiliiy iri the com-munity, The number, spacing, and size ot sample plotsihould be selected according to the sp;i1ial sca!c of thevegetation struc ures in each type of coniniuni y Curran

d Wifliamson t%6, Webs cr c al. I 989!. I'urther strati-fication ii often required within c<mimuni ties because of'struc ural differences that at'tcct their spectral reflectancecharacIeristics e,g., shor . rncdiuin, and rail plots f<ircordgrass!, Considera i<in of thc c<irnmunity's phenol-ogy and growth form v ill intluence thc temporal dirnen-sion of he sampling program. I'wo approaches are iug-gei ed: sampling at times characteristic of each stage inthe vegerari<irr 's growth cycle e.g., spring green-up. surn-mer greenness peak, fall scncicence, arid winter dor-

maricyr and sampling a the period <it peak greenness orepresent vegetation condi ion, Carcf'ul recordi .shouldalio be made of the sky and cnvironnicntal conditioni ateach sampling dare to account for any variability in datanot explained hy the measured biophysical pararnctcrs.

Once large samples of spectra! ret'lcctance and bio-physical parameters have beeri collected at <ine or sev-eral periods over the grov ing season <it the vegetation ofinterest, relationships can be dcvclopeiland niodcli ap-plied. The strength of the rclati<inihips or scnsirivi y nfthe model to the range of measured values should beexamined firsl The established relationship or m<ideloutpuri are then validated. I or rhe empirical approach,either simple regressi<in or correlation echniquci can beused. the biophysical parameter is he dependent vari-able, and the measuremen ol reflectance is the indepen-dent variable. In deterministic rnodcl s, the mcasuremerit iof spectral reflectance are I.ran sformcd and used in equa-tions ro estimate the variable of interest. Sensitivity anderror analyses can be done with these models to deter- nine he effects of ernrrs in. the input. Measured bio-physical parameters are used 1o validate the output ofthe model,

Itnagery. Two approaches are commonly uicd ro re-late spectral brightness values froin an image of a resto-ration site to the condi1ion of vegetation on the ground.Both approaches are empirical. The first uses a relation-ship already established e.g., for radiometric data! be-tween spectral reflectance and a biophysical parameter.tn the second, this relationship is es abhihed betweenpixel values and conchtions of ground vegetatiiin sampledover larger areal units to correspond to the large gr<iundresolution element of an image compared with a hand-held radiometer!. Spectral brightncss values are extracted

from each pixel corresponding to the field samplingsites. 'I'he image da a should be calibrated ro absolutercflec ance or radiance values made at the time of rheoverflight.

6.4.5 Case Studies

In San Diego County, Cat cans is currently responsiblefor creating rwo miertidal wetlands along the easternihore of San Diego Bay. The f<illowirig sections surn-marize how remotely sensed data were applied to pro-vide informarion for monitoring rhe progress and suc-cess of various Caltrani restoration prolects.

<iweetwater ittarsb restoration project: Habitatfor light-footed clapper rails. Construe ion of theHrgh<vay 54 overpass with Inreri are 5 in Chula Vistain I 984 damaged a par of he tidal wetlands in the Para-dise Creek Marsh and t'illed areas adjacent oSwee water Marsh. One objective of mitigation was toprovide sustainable vegetated home ranges for the light-footed clapper rai t. These birds require a habitat with aspecific mixture of hnv-, middle-, and high-marsh ar-eai. Within the low part of the marsh, cordgrass mustalso provide suitable cover of a specified height. In or-der to a~sess the success of efforts to provide mitiga-tion. the number and areal extent of potential homeranges Fig. 6.3A! of clapper rail~ must bc assessed,and areas of vegetation of low-, middle-, and high-marshspecies muit be calculared. We derived these areal esti-rnates by using high-resolution airborne digital multi-spectral imag.c data.

An airborne data acquisition and registration ADAR! System 550 ! image acquired in June 1995 wasused in the image-classification procedure outlined here.Results <if a previoui image-classification exerciie inTijuana Estuary shov ed thar the different assemblage~of plant species were moit separable on this type ofimagery during the March � April or July � Augusr pe-riod Srow e1 al, I 993k Specific derails f»r rhe image Fig. 6,3bi are ourtined in Table 6.7.

In or<ter to delimit patche~ composed of similarmarsh vcgeta ion. a per-pixel supervised classifica ionwas applied ro the data. On the baiis of initial fieldinspections. areas of known types of ground cover wereselected as "training sites" for specific asiemblages ofvegetation. Those areas v here training sires could notbe de t ined because of mixtures of vegetation e.g., highmarsh iites! were classified by using computer-gener-a ed chissei. Once the image wai classified. the accu-racy of clas~ label s and b<iundaries wai tield checked.This check ensured tha each class v ai tahe led accord-ing o the dominant type of marsh vegetation occurringin iti boundaries and hat the boundaries did deli nitzones <if r miition. Mislabeled classei «ere hen cor-rected, and poorly defined classes v cre reclassified.Labels for the final image classes were selected to en-able direc evaluation ot'rhe segetarion distribu ion as

94 TIDAL WETLAHO RESTORATION

potent tel habitat for clapper rails and I <ir separa i m intohigh-, middle-, and low-marsh zones.

The final product from the classificatiim and iieldchecking was a classified image of thc Sv,cetwater Marshrestoration site on June ! !, 1995 Fig, 6,3B i. Pixels withinthe satne marsh type high, rniddle, or !ow! werc giventhe same labe! and merged e.g., all those cover typesconsidered to represent assemblages of high-marsh veg-etation were aggregated into one c! assi. Results are surn-marized in Table 6,7. indicating which potential homeranges exhtbit the required acreage under current andfuture conditions, Seven horne ranges for clapper railsare close to meeting the criteria, and three cou!d complywith future expansion of marsh vegetation, The estimatesindicate an increase in areas of lov,-marsh type, abovethe required threshold for each poten ial home range. Thesite was refhiv n in ! 995. and areas of dense cordgirassand high marsh were not the same for the two censusperiods, This was because of differences in water levelsand illumination, both of which affect the spectral sepa-

rability of plants,Sweetwater Marsh; Monitoring the effects of soil

amendments Because restored marsh soils are deticientin nutrients and nitrogen, the effect of fertilizing hem isbeing established Boyer and Zedler 1996, and in prepa-ration!. Hand-hc!d radiome ric measurerncnts were ob-tained for a variety of pure cordgrass pio s treated withdifferent amounts if nutrien s urea added in differentmomhs and from 2 to 12 times!. The spectral reflectancedata were examined in relation to i.ordgrass total stemlength, density, and amount of foliar nitrogen to aid eci>-! ogi eel mrinitoring.

An Exotech four-band radiometer was used o mea-sure spectral reflec ance in blue, green. red and near-in-frared wavebands of the reated plots. A single measure-ment was obtained over the center of each of 702-m x 2-rn plots of pure cordgrass. There were four transects onthe Nor h Connector fslands and three transects on t.heSouth Connector islands. Each transect contained 10plots. Within each transect. nutrient treatments were as-signed by using a randomized block design, Measure-ments were taken «t three stages in the ! 993 growingseason. in April, July, and September.

For each sampling date. analysis of variance ANOVA! was used to deter nine if t.here were signifi-cant differences between he NDVI values for plots thatreceived different treatments. Regression analyses werethen done to assess possible relationships between thevegetation indexe~ e,g,. YDVl! and measurements of'stem length. A tentporal-differencing analysis was alsodone for aB the data collection periods to determinewhether there were significantly different spectra! indexchanges in plots given different treatments.

Statist!ca!fy significant differences were observed for!qDVI values associated with different treatments {Fig.6.4!. As the number of applications of nutrients increased.

Figure 6.3A Potential home rar ges for the light-footed clapper railat a 6.9-ha constructed marsh within Sweetwater Marsh NationaiWitdhfe Refuge Polygons of suitable size �.8-1 6 ha! were drawn trrinclude low, rniddle and high marsh habitars The area of each hatrr-tat type within each potential home range was then assessed usingAOAR imagery Fig. 6.3B1.

so did thc s'DV! values. !his suggests hat the !siDVt issensitive to changes in cordgrass stmcture and abundancethat were observed when the radiometric mcusurernentswerc obtained. l' or lhe regression relationships betweencordgrass spectral and biophysical measurements, no sta-tistically significant r- values were observed for hlDV!,near-infrared, or rcd ref! cct ance values regressed againstcorresponding stem length, heigh . density. and foliarnitrogen va!ues in all plots, Several factors may accountfor the low r values: �! Senescing vegetation liad longstern lengths bu low NDVf va!ues; �! Standing wa erin some plots reduced NDV! values; �! Plo s with tlat-tened stcrns had higher h!DVf values than plots withstems of the saine leng h that werc not flattened: and �1Spectral measurements were insensitive beyond a par-ticular ievel of biomass. Further work is required to de-termine the exact plant charac eris ice represented by hespectral reflectance data for single sample dates and over ime

Sweetwater Marsh: Cordgrass spectral and bio-

physical parameters. Total stem !ength of cordgrass canbe inferred from spectral vegetation indexes because bothquantities relate specificaliy to plant biotnass Gross etal, ! 989!. Hand-held radiometry provides an efficient and

50 10050

Rgure 6.3B Marisma de hlaadn. Sweetwater Marsh N*tionai Wildlife Refuge, shcwrrig habitat types differentiated from an airborne dataacquisition and registration System 5500 image taken on June 10. f 995. Black-and-white prints do not distinguish ail cover classes, but low.rnidtge, and high marsh habftats are clearly indicated on the color version, which is used for management purposes.

COVER TY~ chan

standwater

~ moissubs

low Spartfolios

midd

~ high

~ highbare/

IMPROVED METHODS FOR ASSESSING ECOSYSTEM DEVELOPMEhlT

Table 6,7. Potential Home Ranges for the Light-Footed Clapper Rail

Habitat Type %1High Low

Polygon Area Marsh Area he cta re s! he c tare elLocation

08 � 16Compliance cntena > 0.8 92 5 15

Curre ntNorth Conneciorislands1 � 4South Connector elands 1 � 2South Connector fsfards 3 � 5South Connector island 6Marsma wea 3Marisma as a 4Manema areas

13104415132816

0 74'.581 440 710. 730.841 24

27382313161931

1.072281 841 051 231 241 90

FutureNorth Connector island 5Mariama are a 5 north Sector!Mafisma area 5 south sector!

0,740 610.64

134715

304081

1 921,02O. 91

hfofe: Polygons that approximated the criteria �.8-10 'l.6-hectare areas. each with at leastI 54/o low marsh and at least 1 5'7, high marsh! in 1994 are labeled current, and polygonsthat might meet the Criteria aa vegetaticn eXpanda are labeled future pOtential hOmeranges. The term potential indicates that birds are not yet using these home ranges ansithat other assent~el attributes of usable home ranges may be lacking. Polygons containmarsh, channel, and some bare areas See Figures 6.3A, B.

0.6

C3 0.4

Z t:<ts

0.2

Treatments

Figure 6.4 Mean values of the norrnalfZed diflerenCe vegetationindex NDVII for cordgrass vegetation in experimental plots atSweetwater Marsh hlational Wildlife Refuge. Treatments differed inthe number of times �-1 2! that nitrogen was added; N='7.

noninvasive means of establishing the total s em lengthin cordgrass plots and guides more detailed analyses byecologists. Similarly. hand-held radiometry may pros i dean efficient means to monitor other changes in cordgrassstructure and condition,

A conceptual model Fig. fi.S! has been developedfrom our research on the variations of spectral vegeta-tion indexes for various cordgrass canopy characteris-tics and from previ<!u» work on thc controls of vegeta-

ion speclral rcfiec a<ice char<re eristics. On the basis ot he model, the followirrg factors should he taken into ac-count as contributing o the s rengrh and weakness of lherelati<iriships hetwccn <'DVI values and cordgrass hio-nras» stem length, lreight, density!:

~ Canopy architecrurc pcrccntage of leaf surface inh<irizontal vs. vertical planes. light penetraliiinthrough canopy!

~ Surrounding features ihat int'lue»ce spec ral values :ilgul c<iverag», soil m<iisture, degree of water ciii.er<ige I

~ Time of <by. solar elevation~ Pr<ip<irti<in of dead biomass and browning of caiuipy~ Possible existence of asymptote in lhc relationship

between vegetation indexes and green biomass <.e..increases in green bioinass do nor increase rhc veg.e fition index beyond a cenain level!

Tijuana V,stun ry: M esocosrn experiment withpickleweed, The effect of different ti bl conditions onthe restoration of picklcwced was examined at the PERLMesiic<isrn Facili y at Tijuana Estuary Ross 1994,Callaway et al., in preparalionl. Three tidal treatmentslfull tidal, ides excluded, and tide waiers impoundediv ere assigned to 74 I-m x 10-mniesocosins aCCordmg tua randonii aed block design. The mesocosms werc plantedwith picklewccd. Iland-held radiometry <x as used to ex-plore whether the measured specrral reflectance va.luescould provide useful information t'<ir monitoring lheg<OWth <if his plat'll.

Measurements were made at m<inthly intervals forlight transrnissi<in, gr<!w h el<mgation of tagged stems!.bare space, and plant cover binary absence or presenceof pickleweed along transect lines!. Detailed measure-rnents of plant c<iver were made down to I.O-cm intervals

iMPROVED METHODS FOR ASSESS h!G ECOSYSTEM DEVELOPMENT g7

Amount ot lnorden: Light Absorbed, Transrnrffed,and Relteored from the Canopy. understory, andSubstrate

aareunt ot l3ireot and aiffu Se Light Ingde st OnCarerpy, unde<a<dry, and Substrate Amount ot ruadent Light Record

in IFOV by Radiumeter

n each lf!-m mesocosiri. Within each I-iii sec ion <if'2

tach mesocosm, three radiometric meuaurenients werettbtaiaed with an Exotech radioineter with u circular"footprint" 30 cm ia diameter. Spectral radiance was alsotgeasttred over halon-coated calibration pane ls and usedtoc<yttve t radiance ineasures to spectral reflectance fac-tors. Measurement dates in l9<� were in April, June, andAugust.

The NDVI was used to assess rela io»ships betweenthe recorded radiance values and pickiew cod c<iver for<aeh type of treatment. ANQVA was used to determineil'there were significant differences betv ecn Nl!VI val-i us fOr different tidal treatments. Interval incan COvertttdex and bare index were exainine<i in rela ion to spec- at reflectance data for each samplittg period. A ternpo-tai-differencing analysi~ was also done by subtracting<DV[, near-infrared, and red values recorded in Junefrom corresponding values in April a»d values in Augustfttxn those in June. ANOVA of these difference valuesgas used to determine whether different treatmentsnused significantly different changes in spectral index,

Statistically significant correlatiotis w er«observedite ween NDVI values and the following variables intf scending order of correlation!: bare space, pickl«weedever, and light transmission for data collected duringApriL June. and August. Significant differences weregbserved in NDVI and other spec ral measuretnents be- ueen the different treatments f'ull tidal, inundated. and <eluded!. ln most cases, individual mesocostns had cor-ttsponding positive NDVI/cover and negative NOVI/ tate space con elation values, Analysis of measured dif-fnences in cover as a surrogate for plant grov thl fortach trench in refatiort to changes in recorded NDVI val-Ley over he same periOds also iiidicated a Signif~CantIt<tsitise correlation.

Figure � Sparer a teresa epee rat reflectance model V. t

According to the re~nits obtained, spectral data fromhand-held radiometric measurements appear tobe sensi-tive to variations in pickleweed cover in the tnesocosmsover time Fig. y.ft!. With the exception of several outli-ers produced by ~tanding water in areas of mediumcover!, increases in NDVI values c«rresponded to mea-sured increases in pickleweed cover Fig, 6.6a!. A corre-spondingly strong negat.ivc relationship was eviden be-tween NDVI and bare space Fig. 6,6b!. These resultsindicate tha the NDVI is reflecting increases in theam<>unt nf pick fewced cover over time Fig. 6.6c!, ln fact,the radiometer was able to detec stressed pickleweedmuch nore readily than vere researcher~ measuringcover and height of vegetation. The <inly measurements hat showed evidence of picklevuced s ress were thegrowth data. which require marking and remeasuringpickleweed branches. Such work is far more labor inten-sive tha» hand-held radiometry. Hence, remote-sensingtechniques offer potential for rapid assessment of veg-etation stress. Further analysis is necessars to accoun for he effects of thc type and state of the soil background moist. dry, sal yl and the change in pigmentation inpickleweed over the growing season.

6.4.6 SummaryMonitorine wetland restoration requires inforination onthc composition. structure, and other hiophysical char-ac eiis ics <it' vegetation at specific spatial and temporalscales. Remote-sensing techniques can provide such datator the charac eristically sinall and fragmented naturaland restored wetlands in Southern California. Threespecific applications of remote-sensing iechniques formonitoring wetlands restoration are I I l identifving andmapping the areal extent of different species and theirassemblages, �! as~essi~g vegetation or land~cape

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Figure 6.6 Scatter plots of NDVI and vegelafion cover, bare space,an< growlb rates of pic<< swee< grown in mesocosrns at TijuanaEstuary.

structure horizontal and vertical!, and �! assessing thecondi ion of vegetation,

Remote-sensing echniques are suited to monitoringres oration for several reasons: I! their noninvasive andnondestruc ive nature, variable scales of coverage, andcapability of repeated acquisi ions; �! their ability to bequantitatively related to structural and conditional prop-erties of vegetatiorr, and �! their cost efficiency.

6.5 ADAPTIVE MONITORING AT TIJUANAESTUARY: Assessing Interannual Variability

It fs a paradox that an e»tuary it! one of' the mildest cli-ina e» in he ;<ii ed State» rank» i<ni<ing the most envi-ronmentall! «ild biologically variable. Throughout heyear, he aver ige nion hiy empcra urc range» only from9' o I'C �8' t<i 69"F, in San Diego, NOAA data!. andaverage <Lazily »<liar in»<ila ion ranges fro n 178 to 6�6langley» Chula Vis a, i976-1977 da a!. Frost i»eX remely rarC alnng the C<ias , and»l<OW i» Virtually un-known. However, whereas tempera ure is predictablymoderate, rainfall and streamf1<iw are n<i , Neither heamoun <i ' fre»hwater influent nor i s tiniing is depend-able.

'1ijui<na Estuary is»imul aneou»ly controlled bvstreamfl<iw volume» and idal circula ion. bo h of whicharc subject o calastrophic change. Wi hin the past de-cade, environitie<ual conditions have ranged from pro-longed drought during an 8-mori h non idal period toprolonged fre»h~ a er inflow».

Natural clima ic variations arc compounded by landrnanagcrnent ac ion» lor example, flo<id control, reser-voir discharges, v,astewater discharges. und coas al landuses that foster erosion!. The c<imbina i<in <if extremeeven » and human disturbance has caused major swingsin estuarine structure and functioning, v'ith incompleterecovery in between, The» ory of Tijuana Estuary is oneof high in erannual variability in climate, sea level.s reamllow, and idal flushing,

Managefnent of Tijuana Estuary ls a shared re»pOn-sibility. Both the California I!epa<tmen <if Parks and Rec-rea i<in and the ll.'S. Fish and Wildlife Service are con-

cerned with maintaining habitat that v ill support severalof the region's endangered»pecie». Al hough quanti a-tive» udie» of the vegetationbegan in 1974 Zedler! 977!.and sarnphng of a large number of fixed»tation» beganin 1979 �edler 1983, Zed!cr et al. 1986; Zedler, Sordby,and Kus 1992!, the si e did not become a National Fs-tuarine Research Reserve NF.RR! until 1982. In 1984.the monitoring became u part of research funded by theNERR program. and in 1988, he nonitoring programwas formalized by NOAA. At various imes, we reevalu-

a ed the measures, si es, and frequency of sampling odocument. and understand interannual variability of thesalt marsh.

In the sections ha fo! l<iw, hackgr<iund data on thephysiography and clima e arc summarized to explain whythe salt marsh has variable environmental conditions es-

pecially soil salinity!. The dynamic» of thevegetation are summarized. and the changes in he moni-toring program are explained. Finally, the value of anadaptive approach to rnoni oring is discussed.

6.5.1 Physiography artd Cl jrrfateGeagraphic setting. Tijuana Estuary �st, 32'34' V, long.117'7'W! is the southvvestenurrost estuary of rhe conti-nental United States. 1 s i ice ion on rhc rcc onically ac-tive Pacific Coast indicates a dyn;rnite gi:ologic set ing.This drowned-river-type es uary is srnal 1 i 024 ha! rela-tive to river mouths along the nrorc ger tie topography ofthe Atlantic and Gulf of Mexico coasts.

The 448,323-ha wa ershcd is mostly �3%! withinMexico. One large reservoir, behintl Rodriguez Dam onTijuana River, and two small U.S. rcservi>irs on Cotton-wood Creek, together control 7f zr of hc watershed up-stream of Tijuana Estuary. Situated 8 km upstream ofthe estuary is the metropolis of Tijuana. Baja California,a growing city of about 2 million inhabitants. RerweenTijuana «nd the estuary is an urbanized and agriculturalriver floodplain with no pristine habitat.

Rainfall patterns. Situ hem Calif'ornia has a dryMediterranean-type ctimate, with mild, wet winters andwarm, dry summers. Averages cf. section 1 1! suggesrthat ramfafl increases gradually from October to a peakin January and February; this is followed by a gradualdecline through April, 'I'he average annual total is 25.2crn. Averages are misleading, hov ever. because a singlemonth may include much of the year's total rainfall. lnDecember 1921, rainfall was 24 ctn. nearly equal to theannual average. The month wilh rhe mos variable rain-f'all is December SE = 0.4!; the leasr variable is June SE = 0,2!.

Rainfall data are better characterized by modes andmeasures of variation than by tneans. For 134 years, thcmodal year had less than 25 cnr ot rain, and only 22 yearswere within 10% of he average. The coelftcient of vari-ability for annual rainfall is 4 fr/e, the SE is 0.9, and therange is 8-70 cm. Because of these high interannual varia-tions in the timing of rainfall and in total rainfall, thepotential tor variation tn streamflow is great.

SfreamAovr. Natural patrerns of strcarnflow roTijuana Estuary no doubt changed greatly with the con-strur ion of the first dam in 1912. Since then, flows havebeen impounded within reservoirs, and peak veiloci ieshave been dampened. With the diversion of ColoradoRiver flows to Southern California and northern BajaCalifornia. imported water has been introduced to theTijuana River, mostly in the fomr of' renegade sewageflows from the City of Tijuana cf. sect ton 3.2! ln rccen years about 198M1991 k Tijuana Riverhad greater sum-rner flows because of persistent flows <tl rav, sewage fromMexico ca. 13 million gal/day!. However, these flowsare dwarfed by variations in winter flood flows and res-ervoir discharges. Interannual variability is high forTijuana River Fig. 6.7!. As with rainfall data, annualstreamflows are better characterized bv modes and ex-tremes than by tneans.

Variability within months ts also high: SEs range from0.8 to 230.5 cubic meters. The least variable months are

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Water Year Oct t-Sept 30!Figure 5.7 Streamf Ow in the Tituana River ShOwS many years wrthno liow, followed by flooding in 1979, I 980, and f 98 3. Oats are fromthe interne iona Boundary and Water Commissions gauge at theUnned States-Mexico border, about 8 km upstream of TijuanaEstuary

those wi h low strearnflow. Seasonal flows lead to highintra-annual variability; years of low rainfall have littlewinter s reamflow and 1 ittle difference in streamflow frommonth to month. This is particularly true for series of'dry years, when runoff i s accommodated by the upstreamreservoirs cutnulative capacity about 160 cubic meters!.However, reservoirs can also prolong streamflows, andcontinuous discharge can reduce seasonality and rnonth-to-month variability. During 1983, record flows occurnsdfrom lvlarch through December when Rodriguez Reser-voir was lowered o restore its 1'lood storage capacity.

Tidal flushing and sea level dynamics. Tijuana Es-tuary is influenced by semidiumal mixed tides. Approxi-mately 50% of the tidal prism the average volume ofwater exchanged by the ides! is attributable to the north-ern arm Oneon a Slough! of Ihe estuary Williams andSwenson l987!. Historic air photos show that whereasthe main channel has been affected by wave washoversand dune erosion, the smaller channels and tidal creekshave changed linle Zedjer, Nordby, and Kus 1992!.

The tidal prism was increased when a landlocked la-goon was connected by a dredged channel sometime be-fore 1924, This lagoon was used as a sewage oxidationpond and made tidal to discharge through the estuaryand into the ocean until the 1960s, Otherwise, the tidalprism has consistently declined. Williams and Swanson�987! calcul.ared changes from topographic maps fromIf�2 rough drawing of open v ater, marsh, and upland!,1976 �.5-m tain ours!. and 1986 �0-em contours!. Theirresults about 2 million ms in 1852 to 0.4 miflion ms in1986! show an 80'% loss in tidal prism over the 134-yearperiod. Seven major flood events occurred between 1852and 1986, fltliing the central embaymenr and the riverand tidal channels. 1 he 1980 flood dumped abou 2 rn ofsedimeft along the southeastern margin of the estuary,ln 19f�, 50% of the tidal prism occurred in the northernarm, which accounts for less than 25% of the reserve.Elsewhere m Southern California. Mugu Lag ton lost409r. of its low-tide volume after consecu ive floods in

1978 and 1980 Onuf 1987!. Sedimentation event» are

rare but are substantial when they occur,Mean sea level rises about 21 cm/century along the

San Diego shore Flick and Cayan 1985!. However, dur-ing the 1983 EI Nino, mean sea level was 15 cm higherthan predicted R. Flick, personal communication!. InJanuary 1983. waves washed over the barrier dune atTijuana Estuary and moved large quantities of sand intothe main northern tidal channel. Sedimentation from the

barrier dune reduced the tidal prism and led to closure of

the ocean inlet. By early April 1984, tidal scouring wasseverely diminished, and the mouth of Tijuana Estuarybecame blocked with sand deposited by the longshorecurrents. The inlet remained closed until December 1984,

when a major dredging program was completed and theestuary and ocean were reconnected,

History wa» repeated in January 1988, when a sec-ond major storm washed sand into approximately 80 mof tidal channel adjacent to the southern dune. This re-duced tidal flows to the southern arm of the estuary Fink1989!. The January 1988 storm was of much shorter du-ration than the 1983 storm, but it occurred during hightide Flick and Badan-Dangon 1989!.

6.5.2 Adaptive MonitoringThe monitoring program at Tijuana Estuary was neitherplanned nor executed with a long-term locus. Perhapsbecause there were no major investments in planning andno contracts to fund specific data gathering, we were freeto improve sampling from time to time. The ability totailor sampling is now recognized as appropriate formonitoring a highly variable system with changing rnan-agemcnt need».

Sampling of 102 stations began in 1979 and was con-tinued annually through 1988. The intent of sampling in1979 was to characterize the cordgrass community acrossits intertidal range, from pure stands along the tidal creeksto about MHHW. The initial stations were established

along eight transect» perpendicular to tidal creeks, with0.25-m quadrats marked at 5-m intervals. Soil salinity2

was sampled at each station by expressing water from a10-cm soil core onto a refractometer. Elevativns of each

station were measured on a separate date, which neces-sitated marking each station. Cordgrass was sampled bymeasuring thc height ol each stem in the 0.25-m2 quad-rat. Measurements werc recorded for each quadrant of

each quadrat, a step that made it po»»ible to compare»mailer and larger sampling areas. Pickleweed and othermarsh plants are less readily measured because of Ihcirsprawling growth form. Estimate» of the percentage ofcover in six classes �, <I, I 5, 6 � 25, 26 � 75, 75 IN!!

were therefore used to quantify thc abundance ofpickleweed.

Because stations were marked, it was possible toresample them in 1980, aftermajorflotiding. Once a majorchange in cordgrass was documented, it was possible todetermine how long the change per~i»ted, Hence, sam-pling continued in 1981 and 1982. Where cordgrass den-sity was unusually high, we subsampled the 0.25-m2quadrat» by randomly selecting one quadrant per quad-rat. Estimates of pickleweed cover were inadvertentlyomitted in 1982, although occurrence wa» recorded. Alsoduring 1982, Tijuana Estuary became part of the NERRsystem. This maintained our interest in the site and, whenthe 1983 flood occurred, we repeated sampling to assessa second freshwater event,

Af'ter 5 years, the investment in annual samplingseemed worthwhile cf. results reported in Zedler 1983,Zedler 1986, Zedler et al. 1986!, and funding was sought.Beginning in 1984, NOAA supported the sampling ef-fort as part of the NERR program. The nontidal periodcoincided with the receipt of funding, and monitoringstations were expanded to 216! ta assess broader effectsof the system-wide drought. Three of the initial tran»ectswere extended 1'arther inland, and two new transect» were

added. We sought to sample more of the estuary but wereconstrained by topography in areas where transect» abut-ted disturbed area~,

ln 1988, after 10 years of annual sampling, we re-viewed the entire monitoring program again. Severalshortcomings were acknowledged, and improvementswere recommended. Although the expanded samplingprogram had added 114 stations, most 85! were stillwithin the range of elevations of the initial 102 stationssainpled. Areas of flatter topography were over»ampled�55 stations between 71 and 110 cm National Geodetic

Vertical Datum, NGVD!, and lower slopes �9 stationsbetween 51 and 70 cm NGVD! and upper»lopes �1 sta-tions between 111 and 141 cm NGVD! wereundersampled. Soil salinities were oversampled littlevariation among stations of similar elevation! for the top10 cm, but the salinity of deeper soils wa» ignored. Sam-pling was also time consuming, because the widespreadtransect» and sampling stations were hard to locate. Fi-nally, although estimates of cover were adequate for as-sessing major changes in canopies, they were too crude +25%! to reveal Ies»er patterns.

Management issues for the region's coastal mar»heswere also considered. Three data needs were clear: I !Relerencc. data were needed for cordgrass marsh,pickleweed marsh, and upper-marsh habitat». so that suc-cess criteria could he established for mitigation projects;

IMPROVED METHODS FOR ASSESSING ECOSYSTEM DEVELOPMENT 101

�! At Tijuana Estuary, a plan Io restore tidal flushingto the southern arm had been developed, and before-and-after data were needed; �! A major question atTijuana Estuary was how sewage flow» front Tijuanawere affecting the salt marsh.

To meet these need», we chose to sample re pre»en-tative areas ol' the niarsh more intensively than befor»and to compare results from areas in both arms of theestuary. The sewage question also suggested a»am-pling scheme that was based on elevation because sew-age would reach lower intertidal area» more often thanhigher areas! and proximity to the sewage-laden river.We placed sampling»tations near the mouth of the riverandnorthward to the most inland tidal creeks. We placedone station near the first area ti> be restored, To retain

our investment in»tations with a decade of accumu-lated data, we retained the option to resample them atintervals e.g.. after a catastrophic event occurs!,

Annual sampling became more intensive, but thenumber of stations was reduced. To equalize effort permarsh type and to improve»ampling preci»ion for mid-and upper-marsh communities on the basis of the domi-nant vegetation, we selected four transect» at each ofthree marsh elevations. Area» of pure cordgras» alongtidal creeks were selected Io represent lower marsh,Areas dominated by pickteweed were selected formiddle marsh, and areas with glasswort and»horegrasswere chosen as upper marsh. A 20-m transect wasstaked at all 12 locations three elevation». four siteseach!. Soil salinity sampling was reduced to three rep-licates per transect, but depths ol'5 � 10 cm and 25 � 30cm were sampled. In order to increase sampling preci-sion and provide measures that were readily compa-rable between species, cover data were taken along 20-m transects. measuring intercept to the nearest 10 cm,Cordgras» heights continued to be measured in quad-rats, with»mall»r size �.10m ! becoming thc standard.The number of quadrats wa»»ct at five per transect,

6.5.3 Environmental Change Within theEstuaryThe changes in rainfall. »treamflow, and tidal flushinghave led to high interannual variability in estuarine wa-ter salinity, intertidalsoil »alinity, and»oil moisture.No long-term records of water salinity are available.J3>»vevex th» acuarv .is us»ia!! v marine except duringmajor winter streamflows. The nontidal period of 1984was exceptional, Atter closure, the estuary water be-came brackish becau»e of impi>unded river water, andthen hypersaline because of evaporation during the longsummer drought. By late summer I9g4, channel waterwa» several degrees warmer than normal, with about >0 ppt salt and higher phytoplankton populatioiis thanever before measured Fong J986; Rudnicki 1986;Zedler, Nordby, and Kus 1992!,

ln most years, the salinity of marsh soils measuredin the top 10 cm! decreases during winter rain» aod»treamflows and increases throughout summer PERL1990!. Highest values are reached in September, whentidal amplitudes are low, The greatest interannual varia-tion» coincided with closure and drought �984!, extremeflooding �980!, and prolonged reservoir discharge�983!,

There i» also considerable spatial variability in soilsalinity; the highest intertidal elevations have the great-est range and sea»onality Zedler 1982!. Within the lowerintertidal part <>f the marsh, daily tidal inundation mod-erates the change in salinity, and soils are generally hy-persaline about 4 ! � 45 ppt!.

Soil moisture varies spatially along with salinity.During September, drought and low tidal amplitude re-duce surface soil moisture in the upper part of the marsh.A similar pattern may also develop in April if there is norainfall, because tidal amplitude is lowest in spring, Atthis time of year, the lowest tides occur during the day-time. and soil» in the upper part of the marsh can dry out.Thc g-month nontidal period of 1984 included little rain-fall, and soils in the marsh and t!dal creek became dryand cracked, with white salt crusts marking fortner pools Zedler, Nordby, and Kus 1992!.

Kffects on salt marsh vegetation. Tijuana Estuaryis largely»alt marsh habitat. The northern arm has thelargest expanse of lower intertidal marsh; the southernarm is dominated by upper marsh and habitat that is tran-»itional to the upland. Pacific cordgrass and perennialpickleweed $ulicornia >irginica! dominate the lowermarsh, wherea» a variety of halophytes intetmix in theupper part of th» marsh Zedler, Nordby, and Ku» 1992!.

Interannual variations in salinity and soil moistureaffect both the composition and growth of marsh plants.Nontidal conditions produced the greatest changes toTijuana Estuary, with severalspecies declining iri abun-dance and di»trihution. Some mortality wa» not apparentuntil 985, Cordgrass wus eliminated from more thanhalf of the 102 lower-marsh monitoring stations. At thesame time, the perennial pickleweed expanded its distri-bution from 75'7c to 87'/< of the sampling stations. Datafrom 215 intertida} monitoring stations show additionalvegetation dynamics. An annual pick!eweed S, h>'gelo>ii!was nearly eliminated from the Oneonta Slough marsh.A short-lived succulent called sea-blite declined to verylow frequency. These changes are related to low soilmoisture, which differentially affects shallow-rooted an->>uafs and de»p-rooted perennial», The perennialpickleweed is known to produce deep roots that can fol-low a declining water table Gri»wo!d I 988!.

Lesser variations in plant growth have foHowed t1t>od-ing and reservoir discharges. Growth of cordgras» andpicklewecd changed with»oil salinity in the fo!fowingpattern Zedler 9!�, Zed!er et al. 198'>!. Periods of low

I 02 TIDAL WETLAND RESTQRATIOfri

streamflow higher salinity. shorter submergence times!favored pickJeweed, whereas heavy streamfiow with lowsalinity and prolonged inundation! favored cordgrass,Cordgrass grew best with prolonged reservoir discharge,and plants channeled excess pholosynthate into vegeta-tive reproduction, so that both height and stem densityincreased substantially, These effects became clear fromthe monitoring record and experirncnral work of Gr iswold�988!.

Associated, confoundirig fartors. The interannuaivariations in Tijuana Fstuary biota are not entirely due tosalinity and moisture. Several factors crrmplicate the re-sponses of vegetation to soil conditions. Nutrienr inputsaccompany streamflow, especially those resulting fromsewage spills. The marsh is knov n to be nitrogen limited Winfield 1980, Covin 1984, Fong 1986, Rudnicki 1986,Covin and Zedler 1988!, and some of the growth stimu-lus associated with reduced salinity is related to increasedinput of nitrogen.

Competitive interactions among the plants Influencetheir respective abundances; best known is the interac-tion between cordgrass and perennial pickleweed IZedler1982, Covin 1984, Covin and Zedler 1988, Griswold1988! Covin and Zedlcr �988! showed experimentallythar pickleweed is the superior competitor for nitrogen.Thus, streamflows with low nitrogen inf!ux may producedifterent responses than wastewater discharges.

Animal abundances both affect and are affected bythe marsh vegetation. Where nitroge~ is present in ex-cess, plan s concentrate it in their leaves and provide morenutritious foods for phytophagous insects. Covin �984!suggested thar outbreaks of a dipteran /rrr errelfa sp.! wereresponsible for high mortality of cordgrass in fertilizedplots at Tijuana Estuary. One endangered species, lhelight-footed clapper rail, depends on the lower-marshvegetation and intertidal conditions. The number of railsdropped to zero or near-zero during the 1984 nontidaldrought P. 3orgensen, Tijuana River National EstuarineResearch Reserve, personal communication!. Reducedcordgrass cover, lack of invertebrate foods, and increasedaccessibility to terrestrial predators no doubt interac edto cause the rails ' emporary demise.

6.5.4 Recovery and Long-Term ImplicationsThe effects of rare. extreme events are persistent, Theecosystem has limited resilience, at least when faced withrnul iple catastrophes within 5 years. The.shift of annualpickleweed from local dominance to rare occurrence isprobably permanent. The habitat where it formerly oc-curred is greatly altered by the presence of a dense canopyof perennial pickleweed. The seed bank of the annualwas apparently lost, when most of its seeds germinatedin spring 1984 and died before reaching reproductive age Zedler, unpublished data!,

Cordgrass was slow to recover its predrought distri-bution Its frequency of occurrence in the 102 monitor-

ing stations ranged flair» 86% tir 939' before tidal clo-sure �979 � 19h3!. It gradually expanded from a low of38% in September 198 s to SI!% in 1986 and 75% in J988.Recovery most likely has been slowed by its chief corn-petiror, perennial pickleweed Clrrswoid 1988!. Cordgrassrecovery wus faster at the lower elevations, where tidalinundation is trequent and soils are anaerobic.

The population of light-footed clapper rails had in-creased to apprrrximately 16 pairs hy 1988, hut it wasnot until I 99 I that the population equaled its predroughtdensity 141 nesting pairs: /crnbal 1991!. The recoveryperiod was 7 years, If the existing population has builtup trorn only I rrr 2 pairs, rather than by irnrnigration.rhe rail's ability to persist in the long term may now berestricted hy low gerietic diversity, The species has someability ro disperse ro upstream or to <rther coastal habi-tats Zcmbal ct ul. 19h5!. bu intramarsh movements arenor common, Thus. Jov crcd genetic diversity and long-term effects seem likely,

Regional implications. High interannual variabilityin Southern California coastal bodies of water produceshighly unstable populations of intertidal salr marsh or-ganisrns. The effects that have hecn documented atTijuana Estuary are mirrored in the regiori's other 25coastal wetlands. Those that remain opeii to tidal flush-ing and occasionally have winter flotrds lbut not pro-Jonged heavy streamflows from reservoirs or wastewa-ter srrurces! support lhc highest numbers of native spe-cies cf. Table 2.4!. Of 19 vascular plant species that wereselected for regional comparison PERL 1990!, 18 arefound in Tijuana Estuary, and 16-19 occurred in five othertidal ecosystcrns of Southern California SweerwaterMarsh, Mugu Lagoon, Anaheim Bay, L'pper NewportBay, and Mission Bay Reserve!, Coastal wetlands thatare usually closed to tidal llushing have reduced diver-sity. Only 5-6 of the 19 species occur in wetlands tharhave long had severely impaired tidal flushing 1 BallonaWetland. Deveraux Lagoon, and Malibu Creek! Thr>sesalt marshes support a near-monotype of perennialpickleweed.

6.5.5 Recommendations for Long-TermIHonitoringThe shifts in data c<!I!ection methods, while disrupt! veto data analysis, have been responsive to changes in bothenvironrrrentaJ conilitions from more ro less variable!and management need». Our carly questions concernedthe interannual dynamics of nesting habitat for the clap-per rail. Mr>re recent concerns are issues of welJand res-toration and the effects of sewage. It is probably a mis-take lo continue a rigid sampling program once lhe short-comings of the programs are recognized. There is nosingle correct way to sample, even if the goaJ of rnoni-toring remains constant, The variability of the systemdetermines the number and size of the samplmg uruts,and interannual variability cannot be known until

IMPROVED METMODS FOR ASSESSING ECOSYSTEM DEVELOPMENT

several years of data have been accumulated,

Monitoring programs are now being required in manyrestoration and mitigation priijects. I'he items to besampled and the frequency and inethods ot' sampling arenow being set before any reconnaissance data are gath-ered, because regulat<iry agencies do not have the luxuryof working out appropriate .sampling schemes beforewriting permit condition~ An overall giial of monitoringprograms for mitigation sites should be understandinghow a wetland is changing through time. Is ot knowinghov or where changes will occur makes it difficult topreset the sampling program. However. measuringinterannual variability probably should take precedenceover detailed measures of spatial variability, unless fund-ing allows both to be sampled thoroughly.

The Tijuana Estuary monitoring prograin indicate~that requirements for monitoring mitigation sites shouldhave a broad mandate. First. the sampling programs

should be undertaken as research programs in them-selves. A variety of attributes should be measured untilit is clear which attributes are the better indicators of

system response. Different sampling units c.g., quad-rat sizes and shapes! should be compared initially toselect those that show low variability within cornmuni-ties. Second, initial samphng should include much largerareas with far more stations than may be needed. Sam-pling adequacy should be reviewed ever! 3 � 5 years.Monitoring station.s can be cut hack once the data sug-gest that cutting back is permissible. Third, a hierarchi-cal approach is indicated, A larger number of attributesand stations can be sampled with lower frequency per-haps 5-year intervals!, whereas more intensive samplingshould be done annually at fewer stations,

To conclude. monitoring program sshould be adap-tive, responding to new information as it is gatheredand to new management needs as they develop.

CHAPTER 7

Adaptive Management ofRestored and

Constructed Wetlands

7.1.1 Rationale for Adaptive ManagementWe expect restoration project» to have a greater chanceo 'achieving their ~lated goaks if suggesti<ins for improvedp arming, implementa ion, and assessmen are heeded.H ov ever, he process will s ill be experimental, Throughiime, developing ecosystems will experience unexpectedeven s, new problems, or uncontrollable disturbances,Along the way. nev inf<irmation may become available,management actions may need o be reevaluated. andmidcourse corrcciions may become necessary. Adaptivemanagement can accommodate such needs. In theFam<isa Slough enhancemem program, algal blooms arean occasional problem, bul the causal nutrien input hasthree potentia! sources and each has a unique solution.Managers need o prioritize the corrective measures af-ter studies «re done to detecl the primary nutrient s<iurce section 7.'.3!. It is a!so possib!e that a restoration sitewill accidently at ract a desired species: p!ans should hechanged if an endangered species unexpectedly c ilonizesthe site. The surprise appearance of lhe California leasttern, an endangered species, necessitated reevaluationof p!ans lo accommodate another endangered bird, thelight-footed clapper rail. al the Chula Vista Wildlife Re-serve. Where unknowns predominate, the approach u>long-term management of constructed or res ored wet-lands should be an adaptive or flexible one.

Many projects g<i awry and require correctivemeasures; in fact, mitiga ion projects rarely develop aspromised Kusler and Ker» ula 1989, Nalional ResearchCounci! l992, Thayer 1992!. Almost invariably, somecomponent of the ecosystem or some critical function is

7.1 THE NEED FOR ADAPTIVE MANAGEMENT

Adaptive management is the iterative approach to man-aging ecosys ems v hen he methods of achieving desiredobjeclives are uukn<iwn or uncertain tii work Ilo!!ing1978, Walters 1986!. Adaplive approaches seem lo bemore appropriate for real<ication projec s than the tradi-tional approach, which would call for imple nenting anentire plan without opportunity for revisions along heway,

lacking. For exaniplc. a tempts o recreate tidal marshcshave not lcd i<i thc devc!<ipmen of soil organic olauerand no rien levels cornparahlc io those of na ura! mar<hex Lindau and II<isncr 19h 1, C raft e al. ! 988.!.angis era!,19911. In addi i<in. invertehratcs in the soil have n<ii de.

vcloped ciimparablc communiiics<Moy and Levin 1991!,shrimp species do nol use transplantedmarshcs as readilyas na ural marshcs Mincllo and /inimerman 1992!. andendangered birds have not been attracted to nest in trans-planted cordgrir~s marshes /cd!er 19931.

In the San Diego area, severa! projects have fallen~hort of rheir grals and v ould lienefi from adaptivenlanagement. At Agua Hedionda Lagoon. hree basinswere excav ated to mitigate damages to picklev eed-d<imi-naicd salt marsh in ! 98'. Transplanted plants were s illa!i<e in ! 986. hut hy 1993 all three si cs had becomebarren salt f!a s. used more hy off-road vehicles than bysah marsh biota Zedler ! 996h!. Corrective measures areneeded. but none «ere required in his early mitigationproject. At a large dredge-spoi! islaiid in San Diego Bay,cordgrass was transp!an cd in 1984-19! S and grev <vefor 3-I y ears unt i!an outbreak of scale insec s occurredIn ervenlion appeared lo he necessary to solve his pri'b.lem lack of a natural insect predator".1 and o cope «iiherosion of the berm that surrounds the island and keepsthe marsh I'rom eroding. !because he island was bui omitigate damages lo natural marsh a!ong the shore of hebay, it seems reasonable to iak< correc ive ac ious thaiwouM ensure the long- enn persia ence of the constructedmarsh. H<iwever. there was and sli is no �1<'.chanisrn «iexplore the need 1'or furrher rniliga ive action or lo re.quire further w<!rk,

ADAPTIVE MANAGEMENTOF RESTORED Af< D CONSTRUCTED vVE7

An adaptive approach is heing»sed o achieve mitia jpn requiremen1S a bw eel w uter Wf arsh in San DiegO

Itaylsecfion 7, .li; lhe success of this intern<'tive manyemen progranl suggests that sin»lar «pprnaches willbenefit restoration of 'tftt hue ares ai Tijuana Estuary,En rix et al, I991!. enhanccnlcnt of I amosa Slough 1 Citypf 5an Diego 199 l l, arid rcs oration <!f 60,7 hec ares of�,e land a San Diegurto Lagoon i Calif<>rnia CoastafCommission 199l!.

72 EXAltftPLES OF AOAPTIVE MANAGEMENT

Ibe California Coastal C<!mntissi on's 1199 t 1 require-ments tor successtul mitigation in<ticate hov' to set up:raeda for successf'ul res <ira ion i Table 7.1!. However.as plans are written. the part on adaptise managementpan be a major stumhling hfock. Problems require rnan-atemet! to select amoilg s:tr!ous options. To shov hova<faptiveptive managemcn can aisist «i h an ongoing sset-tan<fmi iga ion projec . <<e des< rihe he San D!ego Baip I and eXampfes of:!clap iso !tlanage!r!en in Otherprp ecl and

aajor restoration projec s of the re»<!n

7.2.f

Refu e: IS f!reetttrrttter Marsh National Wildlifegs: Intpternenting Adaptive Management

" r 'S !d<'n <rr!d Jr! ! Ze<fi< v.

Cal rans and the r ' She L.S. Arms Corps ot' Eriaineers are he-!pt reit !fred toI < mitigate fos. <it hah! a! c.<used hy c<!n-stnre ion of anev fs rreewas mielch iileean existing freeweeWay and exc is 1 'on ol ' 'cpp rot channei. ThThe onginat n»tig,ition requirenlents

a ed that 76 h6hectares he se .!»<t«. By f<fXf!. the des-S 111 no't he<'il deed e<f '1 o a puhl lc agencs.k ux' Sierra Q nb andand t!!e League lni Cnaslal Pr<!rec ion

g "c'es ins'ols'ed and sr<!n. The O' S. Fish andielOg teal Op1!O ss,ls res ised, ss 1th

1110nat mitt a i requiienleil ts, ii I 8-tl ' 'tare!!ODIOUS staildilr<ts for success 'i!rid loilg.

m att orin<! I fr<! f "t 9 hrough con!pl!ail< e ss! h

'Source: California Coastal Commission 1991

7,1.2 Constraints[ndefs andahtv, ag{ nc'les c'h irged

f'1 fr

live management aPProachcs, bccau,ii iltie costs of pfo]ec s and inPl P ojec s. In addition, a c]ose !n e �.p al experts who deand research, periodic i!lee ,n �

rng.e difficuh decisions ss r ll b needed. Ihis is unfamil-iar terrain for contracting officers. an<i here may he re-!is ance to the concep . Further!nore. there are no guide- !ppksfor writing adapt!< e rnanagem<.nt plans tor projectsspphas wetland restoration. s<! it mas he difficult to findppppte who can prepare the necessary <incuments

Table 7.1,., Minimum Standard

M'igation at San Diegulto Lai a o goon'

inimum standards

1. Location within Southern California Bi ht.otential for r anestoration as tidal wetland,with extensive inte 'ertidal and subtidal area .reates or substantiall r60.7 ha ia y restores a minimum of

a of wetlands, excludin bu f nd tran itio

4. Provides a buffer zone fone of an average of at leastas mea

m wide, and nof less than at least 31sured from the upland ed e of them wide,

transition area geo te

5. Any existin g contamination problems at the sitewould be controlled or remediated and whinder restoration. ia e and would not

6. Site rep servation is guaranteed in per t i throu h a rpe uityownersh'

g ppropriate public agency or non- f'-pro itnership, or other means approved by theExecutive Director!, to protect against futuredegradation or incompatible use.

7. Fea ieasible methods are available to protect thelong-term wetland values on the site, inperpetuity.

Objectives

1. Provides maximum overall ecosystem benefits,for example maximum upland buffer enhancement of downstream fish values, regionallyscarce habitat, and potential for local ecosystemdi versity.

2. Provides substantial fish habitat compatible withother wetland values at the site.

3. Provides rnaxirnum upland transition areas finaddition to buffer zones!.

4. Restoration involves minimum adverse effectson existing functioning wetlands and othersensitive habitats,

5. Site selection and spemfic restoration planreflect a consideration of site-specific andregional wetland restoration goals.

6. Restoration design is that most likely to produceand support wetland-dependent resources.

7. Provides habitat for rare or endangered species.8, Provides for restoration of reproductively

isolated populations of a native Catiforniaspecies.

9 Results in an increase in the aggregate acreageof wetland in the Southern Cahfornia Bight.

10. Requires minimum maintenance.11. RestoratiOn projeCt can be accomplished in a

timely fashion.12. Site is in proximity to the San Onofre Nuclear

Generating Station.

106 TIDAL WETLAND RESTQAATION

the permi ! to evaluate he functionality of he mitiga-tion sites. Two marsh excavation projects werc requiredto mitigate darnagcs under Section 7 of the EndangeredSpecies Act U.S. Fish and Wi!dlife Service !91 t!!.

An adaptive management approach was no required;rather it evolved front four factor<« I ! mi iga ion crite-ria that required persistence of biological attributes, �!momtoring and remedial measures to correct any prob-lems, �! agency biologists with f'oresight and willing-ness to work with technical experts. and �! a researchgroup that wa» interested in understanding differencesbetween the natural and constructed v et!ands PFRL!.The revised standards ct. Table 2.g! for the constructedhabitat were based on perceived needs of three endan-gered species that were je<ipardized by thc projects U.S.Fish and Wildlife Service 19gt!!: for the lower intertidalmarsh, the light-footed clapper rai!; for the middle andhigh marsh. salt marsh bird's beak. The channe! s were toprovide foraging habitat for the California least tern.

ln ! 9gg, PERL was asked to monitnr several attributes

suggested by the revised Biological Opinion, includingquarterly sampling ot invertebrates and fish seining! todetermine species diversity and abundance; monthly sam-pling of wa cr for salini y. dissolved <oxygen, and nutri-enrs; annual sampling of vegetation for composition,percentage of cover, and cordgrass height. and monthlymonitoring of soil salinity. Annual rn«etings were re-quired between PERL, Cahrans, the U.S, Fish and Wi!d-life Service, an<I the LI.S. Army Corps of Engineers, af- er dissemination of PERL's annual report of monitoringresults. This was the beginning of aii adaptive manage-rnrnt prograin that continues to date Fig. 7.!!.

Of the mitigation requirernen s, only the criteria fordiversity and abundance ot fish were sa isfied in the hrst hree years ! 989 � !992!. At the 1992 annual meeting, itwas agreed that fish sampling could shift from quarterlyto annual. Costs of tish monitoring were hus reduced,and he savings were available t'or assessing the popula-tion of salt marsh bird's beak in its first year of compli-ance monitoring. Creating naturally functioning saltmarshes has proved more difficult, and an iterative ap-proach has developed, v ith field comparis<ins of natural

d cons ruct.ed marshes. field experimentation to detectproblems, implementation of recomntended actions, andthen further comparisons and experimentation.

While monitoring was ongoing, PERL obtained fund-ing from California Sea Grant to make detailed compari-sons of the constructed and natural marshes Swift !988,Canti! li !9f! 9, Rutherford ! 9t!9, Zalejko 1989. Langis etal, 1991!. Later research projects funded by CaliforniaSea Grant and NOAA's Coasral Ocean Program! focusedon methods of growing cordgrass to support the endan-gered light-footed clapper rail. The at tempt to create suit-able habitat for clapper rai ls i 1lu st rates the adaptive man-agement approach- The density of cordgrass was even-tually cotnparable to that found in na ural marsh areas,

but h» plan s were o<> sh<irt t'or a bird that buikls a float-<ng nest that needs t<i rise and fal! with the ide Zedler1993!, Soil analyses shov ed that the coarse soils weredeficient in organic ma ei and nitrogen and suggestedthat nitrogen 1«vela coiild be enhanced through soilamendments. cf. sec i<iw«d PLRL to do a pilot study in a sec-<ind mitigati<in niarsh <i »<impar» different fertilizationtechniques. Ca! rans lurth«r <igrced o adopt the recom-mendatinns for s<iil preparaiio<i before transp!antingcordgrass thc year after the study. In 1990. experiments!plantings showed that additioris of nitrogen increasedstein height rn<is when both organic a!fa! fa! an<i inor-garlic ammoniunl sulfa c! rli r<igcn were added. He ice,in 1991, Ca!trans r«t<i i!led alfalfa into the cordgrass trans-plantation sit»s and added fertilizer pellets to each plant-ing hole. PERL continued i<i f<illov the cxpcrimen alplots, and in 1992. when they were 2 years old, it v asclear that <in«- i<no addition of nitrogen was insufficicn to induce grovs th ot' cordgras» tall enough to support nest-ing by clapper rails Oibson et al, 1994!. Two simul a-neous experiments showed high rates of decompositionof alfalfa and rapid loss of nitr<igcii from sandy soils,explaining v'hy <me-tirn« fertilization was inadequate. Asubsequen exp«rirnent was designed to test the effec-tiveness of repeated fertilizaii<m, with variations in thetiming and duration ot' app!ica ions, And, because theresults of the initial experiment suggested that nitrogenfertilization might rigger infestations of' scale insecrs oncordgrass. the effects of repeated applicatio~s of fertil-izer on scale insects <vere assessed al<ing with cordgrassresponses Boyer a<id Zedler 199f<!. Results Boyer andZedler, in preparation! i tdicated tha cordgrass requiresrepeated nitrogen fertilization to grow tall, and Cal runshas authorized more widcspr»ad and longer errn fertili-zation of the construe .ed marshes. I is h<iped tha thcsystein can ultimate!y become self-sus aining, but i isnot certain how long correct ive ineasuies will be <<ceded

Although he mitigation project at San Diego Baybecame an adaptive maiiagement program, it might havetaken a different route if several factors had been differ-ent. Thc major impetus was a civil suit that forcedCa!trans and the U.S. Army Corps of Fngine<.rs to corn-ply with the Endangered Species Act, specifically theBiological Opinion of thc I.I.S. Fish «nd Wildlife Ser-vice !988!, which required that hahitats be resilient forat least 3 year.' and tliat remedial action bc aken in theyear following defection of thc prob!em, Other factorscontributed to thc evolu ion of an adaptive approach, Themost important were that I ! Ca!tran» had a vested inter-est in the success of the project, �! Ca!trans biohigistswere willing and able to f'aci!i ate research to s<i! ve prob-lems, �! Ca!trans dcsigna ed knowledgeable wetlandbiologists to oversee he pro!ect. and �! the moni oringwas contracted to a laboratory that was part of an aca-demic ins itution. Thc last factor was probably critical.

ADAPTivE MANAGEMENT DF REsToRED AND CONsTRucTED WETLANDS

OBJECTIVE, Provide tall cordgrass for nesting habitat for clapper railsPROBLEM: Coarse soils do not supply adequate nitrogen for cordgrass to grow tall

Amend soil at time of transplantation?

If the site is bare

Fertilize throughout the year

L Experiments show rapid decomposition of organfc matter and rapid leachingfrom soils, explaining short-lived effect of nutrient addition on cordgrass growthand suggesting experiments with repeated nitrogen addition. Continue annuallyuntil cordgrass can sustain itself,

Rgrfre 7.1 part Of ihe adaphve management prOgram at Sweefwaler Marah, San Diego eay, CalifOrnia, where the tranSplantedcordg ass is foo short 'or nesting by clapper rafts An iterative program of research, racommendatrons implementation, and furthestAy has been evoivii g since 1 9SS Square boxes = management actions. round boxes = data obtained and recommendationsmade, unboxed phrases = management questions.

because the principal inveshgator. involved were inter-ested in understanding the problems w ith the construe edmarshes, werc able to tind students to put sue differentstudies, and were able to secure funding for that research.A further essential ingredient nay have been the abilityof both Caltrans and univei sity biotogis s o understandeach others' views and responsibilities.

7.2.2 San Dieguito Lagoon: Establishment ofan Adaptive Management Restoration PlanThe California Coastal Commission CCC l 991! is re-quiring Southern California Edison to restore a mini-mum of'b0,7 hectares of tidal we lands at San DieguitoLagoon as panial mitigation for the effec s ol con inuedoperation of San Onofre Nuclear Generating S a ion. TheCommission established success criteria before selec- ion of the mitigation site, so the requirements are rela-tively general. Seven minimum standards were given t'orthe site and the preliminary plan including a guaranteethat the site wouldbe preserved in perpe uity "to protectagainst future degradation or incompatible land use"!.In addition, the restoration plan had l2 objectives, in-cluding provision for maximum overall ecosystem ben-efits, a maximum upland buffer, enhancement of doss n-stream fish values, regionally scarce habitat. substantiatlish habitat, minimum adverse effects on exis ing wet-lands and sensitive habi ats, and habitat for rare or en-dangered specie~ cf. Table 7. l !.

An adaptive management approach is required. Spe-cifically, the Commission requires long-tenn manage-ment hrough the life of the operation of San OnofreUnits 2 and 3!. monitoring before and after the projectbegins, and remedia ion of any failure to meet thew goalsand standards during the fuH opera ional years of Lni s2 and T.

The aspects of the plan that are truly innova ive arethe requirements for "inaximum overall ecosystem ben-efits" rather han single-species targets, the long-terincommitment of the mitigator, reliance on a scientificadvisory panel o oversee the mihgation v ork and moni-toring, and the ability to require remedial actions. Theexecutive direc or of the Commission has responsibilityfor prescrib ng remedial measures, Both physical andbiotogicat performance standards are given: failure oachieve any of these standards would set in motion aseries of changes in he requirements for the project andi s monitoring program.

The San Dieguitu Lagoon is already highly modi-fied, with a freeway across the rniddle, a highway acrossthe mouth. a racetrack. and fairgr<iund near he mouth,and urban development on both sides. An unusually largepari of the river valley is undeveloped, and a plannedregional park should ensure open space upstream.

One basic problem is that idal flushing will not beeasy to sustain. Like many of the region 's coastal bodiesof water, San LaLaieguito Lagoon tends to close to tidal

f! ushlii ',<s saiid builds umn]er I I

i i oil !am«o» i,

lie cia . lii' saiid isusiiing is

restoi do mproie

"a er ' cula lianegional

rid incre.pnsm as a

mians <!f pros idillg v<!nIllluous idal inltuenCI he inle of San Dieguit<i Lagoon is far fron !e

w ctland are<i ha « ill bcconie he restored tidal we la�dThe hydrologic conniction v i h the ocean has beer de.scribed as a "s rav," because it is long and narrow an4constrained bv adjaccn devel oprnen . Thus, any 4 edging ui improve the idal prism mus occur well inland ofthe mou h. The t'i'<.hnology ol designing inlets and ida]pris ns so hcv can provide self-sustaining tidal hydm.logic i<indi i<uis is not sufficient to guarantee success,Thus. a series <if rials and remedial ac ioiis likely willbe nc«ded. Ki h increased dredging or modification o!thc inle come alterations ui planned hahitats and effec son biota. Decisions to increa~e the area dredged will thusrequire expert consul ation and careful consideration. Thescien il ic adv isory committee established by the C'oin-missi<in will be an essential part in the process of adap-tive management.

A second problem will be providing habitat I'or en-dangered species. To date, such efforts have no beensucce~~ful, a leas not in the long term, One plant, sahmarsh bird's beak. has been rein r<iduced <i Sweeiwa er

Marsh. but inainly io remnanLs <if natural hahi a , wherepollina ion may be limiting tlie seed crop cf. sec ion2.4I. The abilitv of bird's beak to persis in construe edv etlands is less certain PERL 1992l

7.2.3 Farnosa Slough: Enhancement ThroughAdaptive ManagementThe California Stare Coax al Conservancy pnivided lun4sfor the C ts of Sao Dieg<i o develop an enhance<ne iiplan for Fa n<isa Slough. a semi- idat we land. I receivestidal flows oiilv tbr<iugh a culvert!. This highly mod fied wetlarid has wo segments, v hich are separated by afour-lane city stree . The v o segmen s arc further sepa-rated from the San D ieg<i River and i s ocean inlet tiy aneight-lane frcev ay. The City pa el over S.t million « he innermos I-ha segment follov;ing a long banlattle be-

tween the owner/developer and local cinzens the Fnee riends

of Farnosa Skoughl. The Friends envisioned enhancements tha would impr<>ve idal flushing while main ai"ing the Slough s open v ater lago<m! habitat foror birds-

>i h $100,$X! fr<im he Sta e Coax al Conservan !c -, Itic

City hired consul an s «devilop a raditionalenI enhance-

ment plan PSHS et al I 993!, w hie h prov ides a long 'nrward signageof potential actions, ranging from straightforwa«at water fi"to cons ruction of a coriipli<'ated one-v ay idal wan via annepanern hat N ould f<irce wa cr into the lagoon '

rcd ed ar theway flap valve, along a new channel <» d«gca~tern and sou hem ends of the triangular la 'oon, an4

ADAPTIVE MANAGEMENT OF RESTOOF RESTDRED AND CONSTRUCTED wETLANDS

ppJf CTIVE: Reduce odors from algal bloomspRpgi f M: Cause ot algal blooms uncertajrt

Circulation too sluggishNtjtrient loa

V bein

Rgure T.g Perl Oi the adaptiue managemerlf plari beiri9 developed lor Famosa Slbugh, San Oiegc. Califbrnia. One of Ihe problems tobe solved is nuisar ca algal blooms. Secause it is unclear what causes rhe algal blooms or what measures will reduce algal growthlCirCuleliOn Or loadingei. an iterative app. Oaoh iS being reCOmntended. Square bcxeS = aCtiOnS. round boxes - data needs unbcxedphrases = ecosystem attributes.

7.3 CONCLUSIONS

f10 TIDAL WETLAND RESTORATION

out through another one-way valve,The Friends pressed for an adaptive»uiiiagcmcnt

approach throughout the planning process 1 heir stra»gpolitical support for the SI<>ugh led to their bec<iming apa t of the appr<ival process, and the enhancemen plancould not go to Ci y Council f' or adoption until the Friendsprovided tex on the adaptive management approach City of San Diego 199 l !. A group ol concerned prof'cs-sionals ook on the task as volunteers and developed thenecessary s ra egy. A decision tree I'<>r several of he sig-nific;int changes proposed for the silough is included here Figure 7.2! o illustrate the role ol' adaptive manage-ment. Water quality analyses are underway to rcssess thesource of'nutrients that may trigger algal blooins PERL,unpublished data!. Depending on da a collection tha willanswer various ques iona, several of the more costly andsignilicant niodil"ica iona may niit need to he done,

7.2.4 Other Projects lit Which AdaptiveIlartagement Is Necessary or Desirable

Batfqttitns I.agoon. The Port of I.os Angeles selectedBa iquitos Lagoo» I'or off-site mitigation of losses <>nearshore fish habitat ha will occur as port facilitiesare expanded. Ba iqui <is Lagoon is closed o tidal flush-ing much morc consis ently than San Dieguito Lagoon,presutnably because the I'<»mer has a heavy cobble loadthat resists erosion during s rearnfiow even s. When the«ohhles are bulldozed o lower water levels in the la-g<a>n, closure generally recurs in a day or twi>. The am-hitious dredging plans that have been developed to in-crease ihe tidal prism ol' Batiqui i>s I.agoon should beaccomplished within an adap ive rnanageinen frame-woik Tile feasoits are nunlerous:

1. The biological functioning of the prerestorationecosystefn has lio been a!isessed, and i is un-clear what values might be irreversibly hist withexcessive dredging.

2. The amount ol dredging essential <> providingfull ti<fal l!ow is uncertain.

3. The ad<ipted plat»akes a conservative approachfrom the engineering perspective the alternativewith mininaum dredging was rejected! and leavesthe risk o biota that may hc unnecessarily threat-ened by excessive dredging,

4 The need for mamtenance dredging is anticipated.

Misskon Itay. The City of San Diego Wallace Rob-erts and Todd et al. 1992! updated its master plan forMission Bay, a I,f�0-hectare recreational park with aboutI 2 hectares of remaining salt marsh. Included in the planis he recon~tructio~ of 2g-36 hectares of salt marsh toenhance natural resources and assist in improving thequa i y of water entering the bay frotn the small but ur-banized watershed. When the time comes to expand thewetlands, it should be done with an adaptive manage-men approach for the following reasons:

I. Th» size urinal configur;<ti<>n hat wouldmost likelypersist given hc til ered tidal an</ streant hydrol-<>gy is unkniiv,n.

2. The sizes, shapes, and qualities of'habitat requiredtii f<>r iinprovemcntin v atcr quality is unk»oss».

4. Ilt» effects <it future drc<fging ngchannels arc unccr ain.

s. Mccllailisnls for pro ec illg wetlands Irotn boat<riganped.

6. Tlie requircnients for type and size of buffers be-tween the >»arsh and adlaccnt urhai developinents<ire Uiiknow�

Adapttve managcmcnt is a usef'ul approach to restora-tion because it offers a meclianism for making decisionswhen it is uiicertain w ha managcnicnt acti<ins will bringabout he desired goals. It should aid several restorationpmjects that are proposed for Sou hem California coastalwetlands. Although hc concept has been introduced ina few restorati<>n plans, it is not yet fully developed as amanagement strategy. Initial attempts have sugges edthe use of decision trees to organize major managementoptions, f' or which decisions must he based on moni or-ing data <>r experinlentaf results.

Perhaps the most important elernen of a successfuladaptive rnanagemen program is the interactionbet<seenthe echnical advisors and the project »tanager. Wi hootaccess to researchers who can develop the necessary ex-periments as needed and withou their willingness otranslate complicated information for project tnanagers,the scientific advice v ill have lirni ed utility. And v,ith-out some understandirig ol' ecosystem functioning onthe part <if' the project manager, the interaction may no be workable. Thus, appropria e personnel <m both thetechnical and managerial sides are critical to the suc-cess of adaptive management.

It remairis to be seen whether adaptive managementprof» ams can be cot>ducted under inn<>vative contractsbe ween agencies and consul ing. If flexibility and abil-ity to follow opportunities are the key ingredients foradaptive management, then agencies will need to ac-commodate contracts that may change in direction andmagnitude from year to year,

REFERENCES

REFE RENCES

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Aherle, B. 1990. Th» hi<ilogy. control, arid cradrca ionof i ntroduced Strut'ti «a cordgrass! worldN ide and rec-ornrnenda iona f<ir i s ciiri r<il in Washington. Wash-ington S a e Department of Natural Res<rurces, Se-a tie, Washington,

Abrams, L. 19S I. Illu<trrrted Flor.a rrf the Pu<'ific States.V<!i. 3, Gerarl!a<'eu<' Ir! S<'rrrphalara<a eae. StanfordUniversity Press, S anf'ord, Cali tornia.

Adams, J.B., M.O. Smith, <irrd A.R. Grillespie. 1993. Irn-aging spectroscopy: In crpretri iori based or> spec ralmixture analysis. In Remrrte r'<vr< lremi<al Arr<rlvsisrElemental rrrrd Mirreralrrr i< ul f rrmpositirrrr. C.N.Pieten and P,A,J. Engler , eds.. Cainbrrdgc Univer-si y Press, Nev York.

Anderson, R.R., and F J. Wobber. 1973. Wetlands map-ping in View Jersey. Plrr>to<,rum. Err< . Remote Seas-r'ng 33;353-358.

Asrar, Ci. 1989. Tlrerrr y and Alrirli< atirrni rrf Ol>ti eul ke-rnote Sensrnrs Wiley & Sons, New York.

Baczkov,ski, S. 1992. The effects of decreased salinityon juvenile Calif<irnia halibu . Parali< hthis< ali fornr'ca.s. M.S. thesis, San Diego State University,California.

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Zedler, J.B., E. Paling, and A. McComb. 1990. Differ-ential salinity responses help explain the replacemcn of native Jun< us < raussii by Tv/i/ra <>rien a/i sin West-em Australian salt marshes. Au» L Ei <rl. I S:57 � 72.

Zedler, P.H�and G. Scheid, 1988. Invasion ol' Carpo-

/n u <» arid.~aii r <ilier fire in a CO«S al Chap«oui si ein Siirila Barb«r;i oun >', '«lilnrnia. Madr<iri<i35: 196 � 201.

Zemhal, R. 1991 [.ighl-footed clapper rail ce»us»<lstudy, 1991 Preliminary report o California Depan-rncnt of Fish and Gaine, July 1991. Califoinia StateUniversity. I.ong Beach.

Zemhal. R.. J.!VI, 1<incher, C.S, Nordhy, and R.lBran»Iield. I <!M. In ra-marsh movernenls by lighi-fno ed clapp<.r r«ils iridic «lcd in part through regularcensusing. Calif'. /!epr. /'i»/< Frame 71:164 � 171.

Zembel, k .. «nd B, M;issey. 1983. The light-footed clap-per rail: Dis rihu ion, nesting s rategles, and man-«gemenl. Ca/-IV< i«Wiid/ife Trans. 1983:97-103.

Zengel, S.A., V J. Meretsky, E.P. Glenn, R.S. Felger.«nd D. Or iz. 1995, Cienega de Santa Clara, a re n-na i wetland it> ihc Rio C<>l<>rado delta MexicogVegetation distrihul ion <ind the el'feels ol water flowreduction. E«rl. /.n<u 0:19 36.

SUGGESTED READING

SUGGESTED READING

Adam, P, 1990. S<>ltnta<sh Fc»l<>gy. CatnbridgeUniversity Press, Cambridge, England.

AHen, J.R.L., arid K. Pye, eds. 1992, Saltntarshes:Fvlorph<>dy>>«»<i<'s, C»nseri ati<>n and Fngineering<Signifi<ance. Carnhri<lgc University Press. Cart!-bndge, England.

Cairns, J.. Jr., ed. 1995, Rehal>ilitating Damagelogy andWildlife Manage>nent. University of Minnesota Press,Minneapolis, Minnesota.

Davis, R.A., Jr., ed. 1978. Coastal Se<li<nent<try Envi-

ronments. Springer-Vcrlag, New York.Davis, S.M., and J.C. Ogden, eds, 1994. Everg ades:

The E<'osysten> an<J Fts Rest»ration. St. Lucie Press.Del ray Beach, Florida.

Jordan, W R. 1H. M.E. Gi lpin, and J.D. Aber, eds. 1987,Restorati»n e<'ol»gy. A synthet<c appr<>ach to ecolngi-< al resear< h. Cambridge University Press, Cambridge,England.

Littlehales, B.. and W,A. Niering. 1991. Wetla><ds ofF<lo>.th America. Thomasson-Grant, Charlottesville,

Virginia.Mitsch, W. J�ed. 1994. C<l»ba! Wetlandst Old World and

>Vew. Elsevier, An>sterdarn. The Netherlands.Mitsch, W.J., and J.G, Gosselink, 1993 Wetlan<ls. Sec-

ond edition. Van Nostrand Reinhold, New York, >V.Y.National Research Council. 1992. Rest<>ration of Aq«otic

F<'<rsystems: Sctence, Technology. and P><blic Policy.National Acadenty Press. Washington, D.C.

Thayer, G.W., ed. 1992. Restoring the lVation's MarineFmironment. A Maryland Sea Grant Book, CollegePark. Mary! and.

INDEX

on! Svstcrn

hen si.<

Bc ding's

9, 102

hie. 80

i.i ai !ficial

122 TIDAL WETLAND RESTQAATION

A< un I<r>>tuhiu> jfuv>manas. See Ye fowf n gobyAdaptive management. See u/><> Monitoring

constrainLX on, 105

examplesFamosa S!ough, 1 !8, 109 fig., 110San Dieguiio Lagoon, 105 Iig., 108Sweetwater Marsh, 105-6, 107 fig� l !8TBuana Estuary, 63, 66, I IX! � 101

interannual variabilihes and, 98 � 1 X!rationale or. 104 � 5. 110recommendations, 103

ADAR airhoriie daia acquisition and regis ra i93 � 94

rhree applications of. 90 table, 97 -98mapping areal extent. 89 � 91vegetation condition. 92-93vegetution structure, 91-92, 92 table

Aguhu>- dr'sin eg> uru< predat<>ry diving beetles!, 78Agua Hedinnda Lag<sin. 47 -48, 61, 104Alanleda reck Fhxxl Control hunnel. 51Alaska, 8A I 'a 1 fa, 70, 106A lgae

f XXI weh source, 87, 88nirrogen levels and, 45t>dul ff«ws and, 3. 12

Ainerican avoce! Re< urrir<>s r<r un>en< uriu!, 7Ar>icrican coot Pi</i«r t>m<'i'r«rn<ri, 47, 78Arncrican widgc<m A>iui arne>i< unu!, 7!trlniniu<iruniii< .>un<I» «'i>n<'><> I><'/<i<>igi..'>'ee

Sav;innah sparrowAiiaheii� Bav. 60Anui u<'uiu pin aifs!, 7! A>i<is un«'ruu>velers!, 78A>ius < r«'.ur p/uivi I>rn< /u» mal!arel�!. 78Au< h<>u <'rin<prr>cdy anchovy!, IAN !VA <ana!ysis ol' variuii.e!, 94Anihi<iiunr <d» unfit<, 2'9. 3 !Arcata trcatmen wetlands Humbold Buy!, 7- 8Arrow goby f I<'t'< Iu>id>air><!. 21, 84Art itic ial Ireshwat cr v;et lands. Srr Freshw a

wc ! a id vA>.un<la Cunur gian reed!. 59A I>erinr>p> ujfin>s. See '1'opsmehAtlantic Coast wetlands, 1. 56. 84, 87, 88, 89A rip/et puiuiu fai hen!, 34A r<p/er seniihurx aiu, 52Auvtra!ia, 49, 50, 52

Back swimmer Buenuu sp. !, 78Bair Island Ecohigical Reserve. 32 table, 34 � 35Ha!Iona Wetland Los Ange cs!. 11

henth>c inver ehrates, � table, 14biophysical/chemic al < haracterist i ca, 18 tablebird spec>es. �hydrologic classification, 12

salt mi>rsh vegetu ion, 14. 17 fig.soil salini y, 17 Iig

Barred sand has> i pa>a/ah>ur nehiihfer'>. 12B<J<> u II'>ssiupifnil<l, 5Ha I9<>< <>s I ago<>ii, I I, 55. 60, 61. I 10Bari< mari >you, 14Bat rav IVvil<>hui< 92 < al J<n!II«' i I, 6Bay Conservatii>n «nd Devel<>pmcn Commission, 36Beaches

con a<un>an v on, 45, 46erosion, 63 � 64

Bees Huii< rus sp.!, 29, 3 !Bees Lusir>gia»un> sp,!, 2'!Bees It>feiiss<>de< sp.!. 29Bcc les, 43, 78Bclding's Savannah sparr<>v, An>n>r>a<run>us su>i</icir

h< Ir/i i i'i !, 47, 59, 8 I � 82. 82 table, 83Benthic channel hubi a , 43, 84B< nthic invcrlc bra ei

in arlificial I'reshv aier we fa»ds, 7!t, 81, 82 tablein construe cd versus natural channe! s, 23 � 24, 43a Los Pef>asquitos Lagoon. 19 tablesalinily impact, 12, 45at Southern Califorriia estuaries, 13 tableat!iweeiv'a cr Marsh, 26 table idal Il<iws and. 12, 15, 16wasiewaier impact, 44-45

B iodiversitymonitoring indicators of, 8 � 84. 82 tahlcas restoration goal, 56, 64tidal iowa .<nd, 3, I I -! 2. 14- 16, I h, 20, 56. 58 � 5

Birds. See u/>'r>!ih<>rcbirdsartificial Ireshv aier v'etlands for, 77, 78, 7'!-80 taendangered, 15, 20 � 21, 22 fig.. 23 � 25, 83, 84at Gog-Le-Hi-Te Wetland Systc n, 38human disturbances arx1. 47. 47 tablePacific Flyway suppii L 7tidal Aov impact im, 15

Bird's beak. See Salt marsh bird's beakBirdwatching, 7Bun<bus sp. bumblebees!, 29. 30Border Field State Park. 63Brass buttons CaruIa r mr>n<>pifniiu!, 5 IBritish Columbia, 39Bucepha/a uiheoia buffleheads!, 78Buenou sp. back swimmer!, 78Buffer zone, 48, 53, 56Buff cheads Bu<.ephaia aIheu/a!. 78Bulrushes Bci>pu> spp.!, 44, 77Bumhlcbecs Bamhus sp.!. 29, 30Butter clam �asid<nnus gigariieus!, 6

Cajeput tree Meiaieucu quinquiner>iu!, 49, 51Cuiidris uipinu dunlin!, 7Ca/<dr s sp. sandpi peru!, 7, 78California. See uiso Southern California

c!irnate, 1endangered species, 83

INDEX

estuarine-d«peiid«ni fish«ries. 6wetland loss. R. 10 iabfc

California Coastal Commission. 47, 55, 56. 62. 108Cab fornia Conscrva ion C orps, 34California corbina I Ment<<irrhi<s undi<lutiis!, 12Califonua Department of Fis!r and Game. 83California Departrncni of Park.s ond Recreation, 98California Department of 'I'ransportation. See CaltransCalifomi» Fish and Garne Cornniission. 8Cahfomia halibut I'aruh< hihys i ahfirrniccrs!, 6, 12. 84, 87Cahfomia killifish Ruri<iuhr< parvipinnis!, 21, 23, R4California kast rem Si< I ria <elhi jrrrns hrrrr«ni!, 20, 21. 23. 24

table. 34 � 35, 83California Regional Water Quality Control Board, 44California Sea Grant, 106Ca!ifomra Sta e Coasia!Conservancy, 33, 64, 77, 108California State Lands Commission, 34California State Resources Agency, 56, 64, 77Cal rans California Departnient of Transportation!, 20, 21, 2 i,

35, 93, 10 s, 106Canadian Departnicnt of' Fi.sheries und f!cearrs. 39Cancer mug<ster' Dungeness crab!, 6, 37Canning River Aus ralia!. 49, 52Canopy architec urc

Io evaluate nesting, 57 � 58. 5 I fig, 59, R3, 84sandy substra e impac on, 69 � 70

Carbon !eve!sin constructed marshes, 42 tablein food webs, 86, 87, 88

Carer Iynghyei sedges!, 3R � 39Carprrhrnrus ed< pha spp.!, 44, 49, 50, 52, 77, 80Central Va!iey California!. 7Channel habitat

restoration of. 20 � 21. 22 flg., 23 � 25thrcc ypcs, 84

Channel v,aieroxygen concentrations. 12, 15 fig,salinity !evels, I'2, 14 fig., 14 � 15

Chara sp, s oncwort!, 77Chesapeake Bay, ICheiapeake Sc <ence, IChinook salmon On< hary n< hus rshav<ytscha!, 6Chrysanthemum, 53Chula Vis a 'Wildlife Reserve, 43, ! 04Churn salmon Onchar vnchus keta!, 6A Citizen's Guide trr pkerfand kesurration Vanbianchr elal.

1994!, 592C!ean Water Act, Section 404, 54Cfeie!andi a ias arrow goby!, 21, 84Cliinate

Pacific Coast, I, 55Southern California. 4, 99Tijuana Estuary, 98, 99

Coastal Science Laboratories IAusiin. Texas!, 86Coho salmon Onchoryn< hus ki sarah!. 6Colorado River, 99Columhia River, l. 7Crsnnector Marish, 20 -21. 57, 69 � 73Constructed channels, 22 fig-

benthrc invertebrates in. 23 � 24. 26 tableexotic inver ebrates in, 24 � 25fish assemhlages in, 21, 23, 25 ablemitigation criteria for, 20 � 2 I, 24

Constructed marshes. See under Salt nrarshesContaminams, 7-8, 45, 46Copper River deha Alaska!, 7Cordgrass Spariirru frr!rrrs<c!

adaptive management of, 106ai disconnected habitats. 43to evaluate nesting. 57-58. 58 fig., 84exotic displacemeni ol, 49 � 50ffafcaspr < densities on, 73, 74 tableat Hayward Regiona! Shoreline Marsh. � 36inierannual environmental effects, 101-2in natural versus cons ructed rnarshes. 36, 69 70nitrogen fertilization. 70, 71 table, 72, 106, 107 fig.remote sensing of. 93 94. 96restoration reconunendations, 73, 75spectral reflectance model. 96, 97 fig.

Ccrrdsdanihuc mannmus ssp. marrrinius. See Salt marshbird sbeak

Core samphng, 23 � 4Crrrtadena utui umen.< o, 52Carraderia seifrrana pampas grass!, 59Cu onw<xx! Creek. 3Coiula c <rrrrnrrprfirfra brass butionsi. 49. 51Coulier gold fields I asthenia gfahraia coul<en!. 33, 49, 59,

Crabs Hemigrapsus rrregnnensrs!, 24Curly dock Rumei. c rispur !. 51 � 52. 59Cyanobactena, 87, 88C ymaiagasier uggregaia shiner surfperch!. 12

Ueepbody anchovy franc hrra c.rrrnpressa!, 12Diamond turb<n i,Hipsr<piertcr gut<ala<a!, 12, 84. 85, 87Diked wetlands. 37 � 38, 40, 41Dipteran In< eric!la sp.!. 102Disking, 53Disric-h!» spica<a a h<>si species!, 27, 31, 5, 58. 59Dow iIchers ILimnrrcfrrrn<us spp. !, 7Dredging

alternatives to, 33deposition of spoii.s from, 36-37, 39. 66substrates frotn, 69tidal flosvs and, 33, 48. 108, I i10 ime/cost factors, 55unknown effects of, 60, 108

Dune erosion. 47-48, 63 � 64Dungeness crab Cancer nragisrer!, 6, 37Dunlin Cafidri < alp<nor. 7

Eelgrass 17~<<tera manna'!, 7Egrets, 35, 78El Capitan Dam. 44Elkhorn Slough, 6, 7El Nigo �983!, 6, IN!Fndangered species. See also Be!ding's Savannah sparrov,

Light-footed clapper rail: Salt marsh bird's beak;Sensitive species

as biodiversity indicator, 82 � 83birds

124 TII!AL WETLAhID RESTORATION

canopy evaluations for. 83, 84foraging habitat Ior. 20 � 21, 2'2 fig,, 23-25

in California h3plants

exotic invasion effects, 49 � 50monitoring frequency, 81three-s ep approach to. 30 � 31

urhanizati on irnpac , 46Endangered Species Act, 20, 106Fnglish sole P!carr>ne< tes v< /u/us!, 6, 37Environinental License Plate Fund, 77Environmental Protection Agency, 54Epihenthic channel habitat. 84Epibenthic invertebrates, 43, 56Erosion

in diked wetlands, 40dune, 47-48. 63 � 64

Fstero de Puma Banda I Bala California!, 14Est i a < I e s

ch<mnel microhubitats of. 84cont amia ants in, 45environmental exiremes and, 15functums and values ol; 6hydml<igic types, 12. Ih tablein Na iona! Estuarine Research Reserve progra n. 7Pacific Coast, Isahiuty levels, 14 fig .. 14- 15, 17 fig., 43-45saJ marsh vege ation, 17 fig.sedirnenta ion prohlems, f>3support of fisheries, 6-7

Estuarine Research Federation. 8Eutr<iphi cat ion, 7, 45Exotic species

in construe cd marshcs. 24 � 25, 27 tabk, 36, 43lish. 27 iahlcin vertebra es, 24-25, 27 tableplantscontrol recommendations, 53, 59hydrol@8 c m<xlificati<ins and, 5] � 52impac on shoreh<rds, 5 tinvasion effect.s. 4849origins, 52suhstrate disrup ion and. 5

Explora ory spat ia I da a analysts, 91

Facultative heiniparasitc, 27. 29Farn<isa Slough, 104, 108, 109 fig., 110Fa hen Anq>i«. puiul«l, 34Fecal cohfortns, 45Field spectrometers, 91-92F»h

catchabilities of, 85 -86. 86 tableco!lected at wetlands. 16 table

Gog-Le-Hi-Te Wc land System. 38Los Penasquitos l,agoon, lb. 18, 21 tableS wee water Marsh, 25 table

in constructed versus natural channel.s, 20 � 21, 23, 37deepwa cr habitat loss, 60-61estuarine habitat for, 6-7, 43microhabitats of, 84mon~toting frequency, 81, 82 able~cine sampling of, 82 fig, 84 � 86, 85 fig.

tidal ll<iws and. 12, 16, 18wastewater iiiip ici a!n, 44 45

Fixxl wehs able iso ope i<nalyscs of, 86 SS. 88 table

FRAG STATS, '! I. 92 tahlc/rrun/,crau i» «a<7</«fin alkali hciith!. 59Fraser River delta British Columbia!, 7Freshwa er artificial we lands, 77 78, 79 SO table, 80Freshwater fliiv s

as mesocosm variable. 75 � 76recy ling rccornmcndat ii>n.s. 45, 46and salinity rcduciion, 43 � 44, 51. 53, 60

Freshwater Slough Channel, 37Friends of'Famosa Slough, 108. 110Fuhiu Arncric«n coot!. 47, 78Full tidal system, I I � 12, 15 - lb. 18, 20Functional equi valency standards, 56-5 7l undu/us purvi piro<is. See California k i! li lish

Gu//<nugn eu//<nip~<> snipe!, 78Gumhusiu ulfi m.< m<xsq uito fish!, 78Ciiant reed Arurulr> <i«nu.i !. 59fi irellu mgrir < opaleyc!, 12Glasswort Su/i< «r<iiu suh/er>nina/is!, 5'!, 83Gog-l i-Hi-Te Wetland Systein, 32 table, 38 � 39, 57Granivory, 29Grays Harbor Washing on!, 7Great blue heron, 47Great Sippewisse lvlarsh Massachusetts!, 84Green-winged teal An«i < re«u!, 78Gulf' Coast werlands, 88, 89

/luiiuspis spur<in«, Set Scale insectst/u/ir./us sp. bees!, 29, 30Halophytcs, 14, 59. 76, See also PicklesseedHand-held radiome ry, See RadiometryHawaii. I, 8Hayward Regional Shoreline Marsh, 32 tahlc. 35 � 36I leavy metals, 45. 46!/em<//rupsus o>eg<>nrnso yellow shore crabs!, 24Herons, 35, 47, 78Home rangcs

for ligh -footed clapper rial. 58. 93 94, 94 Bg .. 96 tableHost species, 27, 31. 58, 59Hottentot fig Carpi>hro/u.i edulis!, 51, 53, 59Humboldt Bay Mitigation Marsh, 32 able, 37, 50Hydrologic classification, J 2. 18 table/fypsr>pse /u gutrula u, See Diamond turbot

lce plant. See Hottentot figimage classifica ion, 90-91, 93 � 94, 96 tableIn< er ellu sp. diptcran!, 102ln fauna. See Benthic invertebrate.sJnsects

in artificial freshwater wetlands, 78at disconnected habitats, 43nitrogen fertiliration impact, 73, 74 table, 102, 106plant-species dependency of, 49as pollinatorss 29-30. 43threatened with extinction, 83

Jnterannua! variabilityof rainfa, 4, i, 99

INO EX

as recommended ineasurcmcnt, 103of saliriity and soi! inoi.s ure, 101 �-

invertebrates..Sr< �en hic invcrtebra es

Japanese mussc! Mui< uh iru sen/r<raiia!, 24-25, 81Jun<' us u<.urui spiny rush!, 53Jun<us /runs.iri, 49

Lagoons, 1 I � 12, 63Landscape me ries. 91 � 92. 92 tableLarge-mouth bass 1 M«r<rprerr<s sa/maides!. 78Lasiag/<cssum sp. bees!, 294<trhenia 8/<rhrur<r «ru/reri, Ser Coultcr goldfields >ague 1'or Cons al Pm ecii<in, 105Leopard shark T<nrrui urrnuruz. Pacitic staghorn sculpinLight-footed clapper rml Ra//«s /nngi r<rsrri s /ei <pcs!. 35, 37

canopy evalua ion for. 57 � 58, 58 fig.. 83, 84cordgrass fcr i!ization and, 106. 107 fig.in food wch analysis, 87, 88foraging habita for, 20-21, 23-24, 24 tableJow genetu. diversi y. 102nesung piit erns, 3, 15. 57 � 58in remo c sensing s udy, 93 � 94, 94 fig., 96 table

/imn<rdr<rmni spp. dov;i chers!, 7Limamr<m < air f<rrnrrunr < seu lavender!, 14Lip<rgruphis feneirre//u salt marsh snout moth!, 29Littleneck clam Pr<rr<rihu«" r srarninea!, 6Los Pcnasquitos J.agoon

bcn hic irivcncbrates, 13 tab!e, 14, 19 tablebird species. 15exotic plant species, 4'L 51fish collected at, 21 tablehydrologic c lass ifica ion, moni oring program, 8!, 82 table, 83oxygen concert iati<ms, 15 fig.sah marsh vegeta iiin, 14. 17 fig.sewer pump station at, 54, 61soil salinity, ! 7 fig. idal flushing improvements, 16, !8, 20 fig., 33vascular plum species, 23 table

Los Penasquitos Lagoon Foundation, 33Ly<ram ca/ifi>nri<um hox thorn!, 3

Macroalgae, 45, 87, 88Macrophytes. 69

a!lard Anus P/arvr/iyn< h<ir!, 78Ma/rrsma /uuri na laurel sumac!, 53Marisma de Nacidn. 70Mark-recapture method, 85Me/aieucu quinq«inertia cajeput tree!, 49, 51Me/<'s.sades sp. bees!. 29Mesem br' un hemi< m spp�52IVlesocosrn experimen s, 45

soil salinity and drainage. 76 fig.at Tijuana Estuarv, 75 � 77. 96-97

Mi< r<rprerus suimnides large-mouth bass!. 78Microtopography, 27, 40Mission Bay San Diego!, 49, J 10Mitigation project~. See also individual sites; Restoration

adaptive rnanagernent apprciach, 1 ~, 107 table, 108, 110

case studies, 32 table, 32 � 39defined, 54function recotnmenda i ons for, 24-25goals/standards for, 55 � 59, 103, J ktregional planning strategy, 55 � 56. 61-63replacement ratios, 55, 60restora ion versus con~ ruction, 54 � 55

Mr<nun h<r< h/ne iinrrra/is a host species!, 27, 31, 5Monitoring. See a/s<i Adaptive management: Remi

assessment methods. 81 � 82of biodi versity indicators, 81-84, 82 ablefish support functions, 87-438food web analysis. 86 � 87recommendations f' or, 102 � 3

sampling programbenthic invertebrates, 23-24bird's beak. 30coring method of, 23 � 24a Gog-Le-Hi-Te VVe !and System. 38a Humboldi Bay Mitigation Marsh, 37seine. 43, 84-86, 85 fig.so isa! mt y, 100at Sv eetwa er Marsh. 106a Tijuana Es nary, 100 � 101water qua Ji ty. ?0-21, 23-24

Mosquito fi sh Gambus<'u affrn<,i !, 78Mud f!ats

exotic plan invasion. 49, 50salt ntarsh vegetation. 14shnrebirds on, 7, 78, 80

Mugu Lagoon, 6, 7, 40, 63. 99 � 100M <s< uii i ra sen/<nus<a Japanese rnusse !!, 24 � 25, 81Muzzi Marsh, 32 table, 36-37sf vu arenarra soft-shelled clam!, 6 My/<7</ruri s ra/<fnrni ca 1 bat ray'!, 6My<rpnrum /ac/am an evergreen shrub!, 51

8, 59ate sensing

National Environmen al Policy Act, 54National Fs uurine Research Reserve. See NERRNational Research Council. 8National Science Foundation, 8Native plants

conservation ethic for 53exo ic <1i splacement of. 48-50

Natural channels, 21, 23-25iVatura! marshes

See under Salt marshesNDV I normalized difference vegetauon index!, 91

and cordgrass biomass. 83, 94, 96, 96 fig,and pickleweed biomass, 97, 98! ig.

NERR hJational Estuarine iResearch Reserve!, 77, 98, 100Nesting sites

canopy evaluations, 57-58. 58 fig.. 59, 83. 84of clapper rail, 3, 15. 57-58of lea.st tern, 34

New Zealand inangrove Ac rennin mariru<!. 49NGVD National Geodetic Vertical Datum!, 100Nitrogen

fertilizationand bird's beak growth, 29and cordgrass growth, 70. 71 tAte. 71-72. 106, 107 fig.effects of short-term, 70-71

126 TIDAL WETLAfs!D RESTORATION

insect pests and, 73NDVI values and, 94. 96 fig.recommendations on. 73, 75

in food v ebs. 86, 87, HHin natural versus construcied marshes. 41, 42 tableorganic matter and. 69. 70plan> competition fiir, 102

NOAA, 8, 98Coastal Ocean Program, 106

hlotth Carolina. 4!, 43, 69North Connector islands Swcctwatcr Marsh!, 94. 96 tableN<»them shovelers Ana>« iypearu!, 78Wo<rr><. sp. a bluegrecn alga!, 77Nurseries, 4!

Off-road vehic!es, 47On< h<irin<-hu.i spp, salmon!. 6Oneonta Slough. 64, 66, 101Opaleye fii t< flu mgru ans!. 12Open-water channel habitat. 84Oregon, 6, HOrganiC rnatter

impact on nitrogen, 69, 70in natural versus constructed marshes, 41, 42 tab!e

Oriental shrimp Puiuemnti nta< rodacryius!, 25Oner trawl, 37Oxygen concentrations. 12. 15 fig., 16O<vi<rajuntai< ensis ruddy ducks!. 78

Pacil ic Coastclimate, I, 55estuary d>versify, !rest<�>riiri on priority. 8tidal paiterns, I, 3walersheds, I, 2 lig.

1'iu:ific C<>asl Terminals Salt Marsh Compensation, 3'!Pacific Estuarine Research Lahiiraiory. See PERLPacifi<' Northv esl, I, 6. 56Pacific i>vsler Ctusii>itrea gtgu<1, 6Pacilic staghom sculpin Lr pit>«>rri<s armurui!, 12, 84, 85Pacilic Termina! s Sat marsh. 32 tahlcPadilla Bay yVashinglon I. 7Pan>pas grass Curia<fr> irt .<elit>unu!, 59Pu>to<rute<> rt runs wandering skipper!, 49. h3Paradise f reck Marsh, 57, 69 70, 71, 72, 93Purui<tht<tr n<'htriif<'r t harred sand basal, 12Puruii<.hrhi i «iitfirrni<'i<s. See California ha!ihulPeregrine fa!con. 34PF.RL IPacilic Estuarine Research Laboratory!, 10. 11

hird's beak recstahhshmcnt. 26 � 27channel monitoring program. 20-21food weh studies, H7freshwater wetland construction, 77monitoring programs, H l. 83

Swee water Marsh, 106Tijuana Fstuary, 3, 96

performance standards. 56shorebird sensnivity experiments, 47

Per-pixel class<f>cation. 91Phylophag<>us insects. 102Pickleweed Saii<v>min higeirnii!, 14, 101

Pickleweed Sufi<.nr.ni,i > it.ettttrd's beak host. 27. 31. 58coarse suhslratC iinpacl, 76exotic displaccinent ol, nlmatnv. species, 69mes<!cosa> experiments. 75

mterannual environmental effects, 101 � 2NDV! values. 83 97, 9h lig.nontidal condit>nns. 101sainpl<ng ri>easuremcnts, l X!spectral ref!ecto<tee measureiiients. 9iv-97

in restoration case stud>ca. 34. 35. 36, 38, 39Pink' sa!mon On< iir>ryrt< hus gnri>io < ha!, 6Pintails Anus a<'itru!, 78Piati< hrhy! steiiauis starcy flounder!, 6Pieurnnei re< ientius English sole>. 6, 37Point Lama sev age treatment plant, 45Point Mugu, 29Po~nt Reyes Bird Obscivatnry Stinson Beach!.7Pollination. See ui<r> fieeds

ofbird's beak, 2<! 30,43Poiypogon monspeitensis rabbitfo<sd grass!. 52, 59Poole Harbour Et>gland!, 49, 50Porphyrin porpiivrio purple swamp hcn!. 49Port oi' L<>s Ange!cs, 60, 110Patumogernn jtiift>roti <. 77Poran>rtgetnn fartfolttr <, 77Prcdal<>ry diving beetles Ag<ihus disitrtegrarus!, 78Predatory diving beetles Rhanru.s sp.!. 78Prorrttha< a srannr<eu littleneck clam!, 6Public access. , 46- 48Purple swamp hen Pnrphyrir> t>r>rphyrio!. 49

Rabbitfoot grass Poiypogini monspeiirrtsi s!, 5 2. 59Radiometry, 91-92. 94, 96 � 97Rainfall

average Southern California. 43, 99interannual variations in, 4, fi, 99. 100Pacific Coast. !

Raiius Jot>girt>strt < ievipe i See Light-footed clapper railRe< utrcrrOslra umerii atta America>i avOCet!, 7Red 1'uxes. 35Reilht>odotirol>tys tai'l i'<'tirris salt marsh harvest mouse!, 34.

Remote sensing. 83advantages, 89, 98case studies

Swee water 'Marsh. 93 � 94, 95 table. 96Tijuana Estuary, 96-97

by image classification, 90 � 91, 93 � 94, 96 i ablewith radiometry. 9! � 92, 94, 96 97

Restoration. See aisn indi<id><a! site i; Mitigation projectsadaptive management methods. 63, 66, 104 � 5, 110case studies, 32 iable, 32 � 39of chaimel habitat, 20 � 21, 22. fig�23 � 25versui construction, 54 � 55defined, 54of endangered species, 25 � 27, 29 � 30f'unction recommendations, 24 � 25goals/standards for 18 20 55 59 103 104habitat/species targets. 62 tablemesocosrn experimentation and, 75-77, 96-"7

INDEX

<nit ignition r;itio on, S5, 60monitoring issues. Hl � 8 . 82 I;<hieNat iona! Rvccaieh Council recominendationc, 8planned tor Sou<Item Calif'nrnia, 61 tablepr<ihlcm c

hiologi<'ul. 41, 43functi<utal viilue loss, <.5hi dro I < ig i c and t v pograph i c. 40inviislic cxotlcs. 48- S2nct acreage loss. 55. 60salinity levels, 43-45urban izatioii. 46-48

regional planning strategy, 55 S6, 61 � 63with revegetation progra<n, 66. 6Hscientific guidance for. 62 table<if ti<hil flows, 11 � 12. � � 16, ! h, 20, 33, 34. 3S

Revegetation program, 66. 68RI<antus sp. I predatory diving beetles!. 7HRh<n<>I>a/as p>odi«.<us shove!nose guitarfishl, 6Rhizomcs. 52Rodriguez. Dtuii, 3, 6. 44, 9<!Ruddy ducks 10.<yu<.aj am<<«ens<s !. 78Rume.i «<<pi

Sa/<'«>rnia hige/<>c« an annual pick!cv'eed!, 14. 10Sali< amia suh<ermina!I s lglaccwort!, 3, S9, 83Saliearm<i ii«;f<!n'<.a See PicklewcedSalinity

bird's beak performance and, 29, 31!in diked wetlands. 41and exotic plant mvasion, 51- 52. 59freshwater discharge and. 43 � 44, 51, 53. 60at Humboldt 13ay Mitigation Marsh, 37interannual variability in. 1 � 2invertebrates' dcpcndcnce <iii, 16, 44, 45monitoring frequency. h I, 8 tableat Southern Califor<iia estuaries. 14 fig., � � .tidal floe c and, 12, 16. 44. 5'2, 76, 76 tig.at Ti!uana Estuary, 76, 76 fig.. 1 K!, 1 vvastcwatcr iiripaci on, 44 � 45

Salmoi'i, 6, 38. 39Salmon River F..ctuury. 32 tahle, 37 � 38, 40Sa/i<i/<i <h< ri« i. 52Saltgrasc, 38Salt march bird's beak I Cord! /an/bus niariri mits ssp.

buffer zone need~, 48as endangered specicc, 59, H3exoiic invasion impact on, 49host species and. 27, 2H fig �29. 31performance standard~ for, 58pollination of. 29 � 30, 43reestaMishnient of. 25 � 27, 29 � 31at San Dieguito Lagoon, �8soil requirements. 29trampling eftcctc <in. 47

Sah marshecbird species in. 15case studies. 32 tahlc, 32constructed

ac disconnected ha hi tats. 43exotic species in, 24-25, 27 table, 36, 4 '

feniliza ion ot. 71i 72functional equivalencv iif. S 7mveitehratc dens<ties. 4!to menage «astccvatcr. 46organic matter le<el< 41 4s I ihlc I<9 7ilioi!s, 41unnitutal ippeamncc 4<!

historical changes in, I cnivasive plants in, 4H-S2natural

dificult duplica iiin iil. 32fertilization ot. 70invertehra e densiiiec iii, 43versi<s restored, 36. 39. 40. 5 Isoils. 41

ratio of tidal flats to. 1,4 tahlcsalinity levels. 14 � I 5San Francisco 13av niap of, 35 fig.spatial prox<villi' <'i'I, HHstable isotope analyses of. H7--HH, HH tableurhanization ctfectc. 1!. 46 � !Hvegetation in ! 4-15

Salt march harvest niouse Reirlu»di>ni<i<ni i r<ii <cen<ri i!, 34.35

Sal marsh snout moth I/.//i«>~<a/i/us /I'<l<'<fl<'llu'i, 9Salt marsh vegetaii<in. Se«di<i Cordgrasc; Endangered spc-

ciec", Picklewced. Salt march bird'c beak: Vaccu!arplan c

consideraii<ms in establishing. 42 tablehydrologic/typographic sensitivity. 4 linsect linkages to, 49inierannua! environmental effects, 101-2invasivc species and, 36. 53monitoring frequency, h!. H2 tablenitrogen levels and, 39. 45, 56performance standards, SH � 59remote censing of

condition. <� iablc, 92 -93iiiapping areal exteni, 89 � 91structure. '� table, 91-92. 92 lable

soii ainendtnent iinpact, 7 ! � 72, 71 tableat Southern California estuaries, 17 fig.spectral ref!ectancc from, 88-89. 89 fig.. 91!tidal Rows and, 3, 14-15trampling effects, 47-48transplantation of, 41

Sampling programSee under M on< tonng

San Diego Bay. 4 rabile, 69. 104San Diego River salt marsh, 52San Dieguito Lagoon, I I

adaptive management approach. 10S fig, 108fish habitat restoration, 60. 62-63hydrologic type, 12stable isotope analyccc. H7-88, 8H table

Sandpipers 1 Calid<as sp.l, 7, 7HSan Eitjo Lagoon

benthic invertebrates, 13 table. 14bird species, 15channel characteristics, 12management targetc, 81. 82 table<ixygeil coitccntrationc, 15 tig.

1 28 TIDAL WETLAND RESTORATION

106

gered

le

le

salt marsh vegetatiim, 14sewage leakage, 45soil .salinity. 17 fig.

San Francisco Bay, 8case study rnarshes, 32-37estuarine types, Iexotic p4nt mvasion, 50-51map of'marshes, 35 fig,regional res oration strategy. 56shorchirds. 7

San Francisco Bay Bird Observatory. 34San Leandro Bay, 36San Onofrc Nuclear Oreneratmg Station, 62, 63, 108San Quintin Bay. 48Save California Wetlands, 8Sivxidrlnnr i glgunt<'vs buncr Clam!, 6Scale <nsec s Hviiv >pi > .<pvritlrv !, 43, 73, 74 tahie, 83.5< irpu.i spp hulrushcs!. 44, 77Sedges I Cur< 1 /ynghv<'I!. 38 � 398 cd>ment acc umulai ion

in co<asia wetlands. 7dike breaching and. 38hydrologic type and, 12organic matter m, 69in restored wetlands, 76tidal flows and. 12. 33, 34, 37, 39. 4 !. 51, 60, 1 X!at T<!uana Estuary, 63, I X!

Seed~<kmor coh>nies for, 26 � 27gerrnina ii>n nf exo ic, 51, .'52hai'id pnf i<nit ii!ii and, 2'!-30sowing recornmcndaiions, 31

Se ine samplingcva lira ion ot. 84 � 86, 8 I llg.

Scmiiliurnal iidal pa tcm, I. 6Scnsitiise species. 5'!, 62, 62 able, 83. Sce i<iso Endan

speciesSewage spills. 45, 9<!, 101!ih el lf> sh, 6Shiner surfperch Cimutr>gviter uggn gutvl, 12!ih ore hirds

a constructed wetlands. 36, 78. 79-80 ahlcex<itic plan invasion and, 5 !human d<sturhances iind, 47un niudflats, 7, 78, 8 !

ShovClniive guiiarfivh Ntrltr>hut<>r plrlrtlri tui!, 6Sierra Club, 105Snipe G«fftnugrr ga!frt<ugr>!, 78SOckCye salmon IOlr< hrlrynr Inr.< n< rf'u l. 6Sett-shel!ed clam trfcv rlrenvri u !, 6Soil ainendrncnts. 7 !-72, 71 able. See ul ill NitrogenS<>il suhstrate. 5«' v/sri Salini y; Sediment accumulatioii

hird's beak re< u<rements, 29disking etTecis on, 53disruption of, 52in mesocosm construe ion, 75 � 76in natural versus constructed wetlands. 39. 41, 42 ahresn>ration recommendanons, 66. 68, 77

South Connector islands Sweet v uter Marsh!. 94. 96 abSouthern Ca!ifomia

climate, 4, 43, 55. 99f<>od source studies. 87 � 88. 88 table

niuniiipal <v,iicr sources. 43need f<>r huf lors. 48resin i<i<0<1

planned pr<>jects. 61 iahleas pri<>riiy, 8. I !rCCOmmenilatii>iis, 61 63

iu.lal patterns. I, 3wastcwa el Iluw s il'l i>, 44v eiliindand river h>ca tons. i! fiuweil,ind hisses, 8, 10 able, 55>

Southern 6 alilorriia liifisim, 62. 63. 108South Slough Oregon!. 7Spur it»l «itcrniflirru iin Ailantic coast spccics!, 36, 43, 49,

5 !, 51Spurtinu f'r>frri>u .<r'<li'il'lnill/Spill ttliu ttlig I<'V, 5 !Spectr al reflectance

biophysical parame ers and, 92. 93. <�. 96. 97 fig.of cordgrass, 96. 97 I'ig.emitted fmrn plurits. hK � 8'!, 89 fig.of pickleweed. '� � '�remote sensing da a «nd, '� � 91

Spiny ru>h Jim<'Itis r«-trt<rx!, 53S able isotope analysis

of t'ood w ebs, h6 � 88, 88 tablestarry flounder Vtutr< !Ithv'<.<tel!uttra!, 6St< rllrr V fbi fir>n> t>rri><ni ..See Calif<>mia 1eav ternS ikine River delta .4laska!, 7Stonewori Churv sp.!, 77Strav arnendrnent, 70Strca<11flow

into 'I iguana Es uary, 6, 9'!, 99 fig.. 101-2Svucdv i it< rvu sea-blite!. 14Subpixel analysis. 91Sulfur levels

in I'ood wehs, 86, 87, 88Swan River Australia! 49 5oSwee water Marsh National Wild i!'e Refuge

adaptive management approach. 82 able, 105 � 6. 107 tig.,108

exotic species. 27 tablelong term concerns. 24 � 25map of. 22 figmitigaiion cri eria, 20- 21, 24 tahle, '�pollhia ion levels. 29 � 30rerno e sensing data on, 93 � 94. 95 table, 96. 96 tablesan>pl ing

benthtc invertebrates, 23 � 24, 26 tableh>rd's beak, 26-27, 30tish, 21, 22, 25 table

Texas. 41. 69Tidal creeks, 68, 84Tidal fla s, 1. 4 table, 60Tidal flows

at Bair Island, 34, 35biodiversity and, 3, 11-12, 14-1 f>, 18. 20, 56, 58-59, 102bird species and, 15classification scheme. 12dredging programs and, 33, 48, 108, 1 10a Los Penas<fuitos Lagt>on, 16, 18, 20 fig., 33

INDEX 12'

40,51, 60,

76 fig.,

8-59, <79,

66, 67

e, 63. 64

Ser also

at Mlrzxl Marsh, 36oxygen conc<'ntratinris,rrid. 12, 16saliriity levels and, 12, 16. 44, 52salt marsh vcgctaiion and, 14--15at San Dieguiiii I.irgnnrr, 108sediincnt accurnulinion and, 12, 33, 34, 37, 39,

I Xlat Tijuana Estuary. IS 16. 75, 76. 99-1�0

Tides, I, .3, 4 table. 5 Iig,. 6Tiluana, t � 4. 45, {>3, 99Tiju>uia Estuary

artilicial I'reshwatcr wetlands at, 77 � 78beach and dune erosion, 63 64bemhic iiivertebratcs. 12. 13 table. 14bird's beak reestablishment, 26, 27, 29, 47bird species, !.Seutr<iphi cat i on and con tamin.<n s, 45exotic plant species, 49, 51, 52fish refuges at, 18hydrologic type. 12localain, 3nionitoring program, 81

adaptive approach, 82 able, I X!-101fish samplinu, 43, 84 � 85. 86 table

nitrogeri levels, 71. 102<ixygeri ciinccntrations. 15 fig.physiography and climate, 98, 99pickleweed mcsocosm experiments, 7S � 77,

9{i-97as reference site. 7, 57, 58saliniiy levels. 12, 14. 14 fig., IS, 17 fig.salt marsh vcgc ation, 14, 17 fig., 101 � 2seasonal/inierannual variabilities, 6, 56, S

101 -2sedimentation problems. 63, ! {XIstrcamflow to, 6, 99, 99 Iig.tidal flows at, I S-�, 99-1{X!tlda I res urn ron plilri, I I

constraints map, 64. 67 fig.hydrologic analysis. 64. 6/iinanagement needs, 63 � 64map of historical changes, 6S fig.research needs, 6i6, 68

trampling effects, 47, 48wastewater llov s into, ~5

Tijuana Fxiuaiy Tidal Restoration Plan, 11, 6:3 � 64tig., 68

Tijuana River, 99, 99 tig.Tijuana River National Estuarine Research ReservTijuana Slough National Wildlife Refuge, 63TKN total Kjcldahl nitrogen! levels, 71, 72 table.

NitrogenTopsmelt A he>in<>psafhni <!. 12, 21, 23, 84/7'rra/'is senrr fascia a leopard shark!, 6Tnchocoriara reticula a water boatman}�-787vf>ha spp. See Cattails

11,S, Army Corps of Fngineers, 21, 34. 3b, S4, 10S. 106U.S. Depanmen nf Fish and Ciarnc, 34U.S. Fish and Wildlife Service.8. 21, 83,98, 106U.S Fish and Wildlife Service Biological opinion, IN. I06U.S. Forest Service. 37, 38U.S. Geological Survey, 81Urban wetlands. 11, 4 r-48

Vascular plants. See also Cord grassfo<rd v eb source, 87, 88at Ixrs Pehasquitos Lag<i<in, 23 tablenitrogen levels and, 45at Southern California wetlands, 17 iabletidal llows and, 3, 12, 16, 102

Wandering skipper Pano</u»ra erron.< I, 49, 83Warm Springs Marsh. 32 table, 33-34Washington state I, 6, 8Wastewater

impact on biota, 44-45treatment of. 7 � 8, 4S � 46

WasteN ater oxidation ponds, 35Water boatman Trr r hr>r orixa > eltculara!, 78Waterfowl, 7, 20, 78Wa er quality

monitoring frequency, 81, 82 tablein natural versus cons ructed channels, 20-21. 23sediment accumulation and, 7

WatershedPacific coast, I, 2 figSouthern California estuaries, 3, 43

Western sandpipers Calrdri s mauri!, 7Wc lands. See alar> Estuaries; Mudflats; Salt marshes;

Tidal flatsbuffer xone rel'ages in, 48, 53, S6Clean Waier Act on. 54diked, 37-38, 40. 41exotic plant invasion of, 48-52federal mitigation policy on, 54-55fish support function, 6 � 7, 43freshwater artificial, 77-78, 79%0 table. 80habitat cl ass it ication, 56historical changes in. 60planned restoration project~, 61 tablerestoration needs/8<sais, 8. 10, 55 � S6seasonal/interannual variability, 6, 101 -2~ediment accumulation, 7urbanization impact, 11, 46-48for wastev ater treatment. 7 � 8

White pelican, Pe/ecanus enthrnrhynchns!, 34Willapa Bay Washington!, 4<3Woodley Island Marina Humboldt Bay!, 37

Yellowftn goby {>tcanthngrrhrus flavr'manus!. 12. 21, 81

Zooplankton, 787osrera marina celgrass!, 7

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