rXXXX American Chemical Society A dx.doi.org/10.1021/es1042244 | Environ. Sci. Technol. XXXX, XXX, 000–000

ARTICLE

pubs.acs.org/est

Bottlenose Dolphins as Indicators of Persistent Organic Pollutants inthe Western North Atlantic Ocean and Northern Gulf of MexicoJohn Kucklick,*,† Lori Schwacke,‡ Randy Wells,§ Aleta Hohn,|| Aurore Guichard,† Jennifer Yordy,†

Larry Hansen,|| Eric Zolman,‡ Rachel Wilson,^ Jenny Litz,# Doug Nowacek,z Teri Rowles,$ Rebecca Pugh,†

Brian Balmer,§ Carrie Sinclair,& and Patricia Rosel@

†National Institute of Standards and Technology, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston,South Carolina 29412, United States‡National Oceanic and Atmospheric Administration (NOAA) National Ocean Service, Hollings Marine Laboratory,331 Fort Johnson Road, Charleston, South Carolina 29412, United States§Chicago Zoological Society, c/o Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, Florida 34326, United States

)NOAA National Marine Fisheries Service (NMFS), 101 Pivers Island Road, Beaufort, North Carolina 28516, United States^Department of Oceanography, Florida State University, 117 N. Woodward Avenue, Tallahassee, Florida 32036, United States#NOAA NMFS, 75 Virginia Beach Drive, Miami, Florida 33149, United StateszDuke Marine Laboratory, Duke University, Duke Marine Lab Road, Beaufort, North Carolina 28516, United States$Marine Mammal Health and Stranding Program, NOAA NMFS, 1315 East-West Highway, Silver Spring, Maryland 20910,United States&NOAA NMFS, 3209 Frederic Street, Pascagoula, Mississippi 39567, United States@NOAA NMFS, 646 Cajundome Boulevard, Suite 234, Lafayette, Louisiana 70506, United States

bS Supporting Information

’ INTRODUCTION

The U.S. coastline differs both regionally and locally in theamount and type of human development, land use, and landcover. Land-use differences among coastal areas are reflected inboth contamination concentration and profile in U.S. estuariesand coastal waters.1 Likewise, land use and population densitiesinfluence contaminant concentrations in sessile aquatic organ-isms, such as bivalves, which have been monitored routinelyfor decades through programs such as the National Oceanicand Atmospheric Administration’s (NOAA) Mussel Watch

Program.2 Not surprisingly, the highest persistent organic pollu-tant (POP) concentrations in bivalves are associated withindustrial areas or urbanization thus validating the utility ofsessile organisms for monitoring contamination of estuarineareas.1

Received: December 16, 2010Accepted: April 6, 2011Revised: March 18, 2011

ABSTRACT: Persistent organic pollutants (POPs) including legacy POPs (PCBs,chlordanes, mirex, DDTs, HCB, and dieldrin) and polybrominated diphenyl ether(PBDE) flame retardants were determined in 300 blubber biopsy samples from coastaland near shore/estuarine male bottlenose dolphins (Tursiops truncatus) sampledalong the U.S. East and Gulf of Mexico coasts and Bermuda. Samples were from 14locations including urban and rural estuaries and near a Superfund site (Brunswick,Georgia) contaminated with the PCB formulation Aroclor 1268. All classes of legacyPOPs in estuarine stocks varied significantly (p < 0.05) among sampling locations.POP profiles in blubber varied by location with the most characteristic profileobserved in bottlenose dolphins sampled near the Brunswick and Sapelo estuariesalong the Georgia coast which differed significantly (p < 0.001) from other sites. Hereand in Sapelo, PCB congeners from Aroclor 1268 dominated indicating widespreadfood web contamination by this PCB mixture. PCB 153, which is associated with non-Aroclor 1268 PCB formulations, correlated significantly to human population indicating contamination from a general urbanPCB source. Factors influencing regional differences of other POPs were less clear and warrant further study. This work putsinto geographical context POP contamination in dolphins to help prioritize efforts examining health effects from POP exposurein bottlenose dolphins.

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Monitoring programs in the marine environment frequentlyrely on higher trophic animals to establish geographic trends ofenvironmental contamination.3 For example, studies undertakenin the arctic and North American Great Lakes regions haveillustrated regional differences of current-use brominated flameretardants measured in herring gull eggs.4 Marine mammals inparticular serve as useful environmental contamination indica-tors; many species are top-level predators and have a highpotential to biomagnify pollutants. Additionally, some marinemammal species such as the bottlenose dolphin (Tursiopstruncatus) have population subgroups demonstrating high sitefidelity for coastal embayments and therefore have the potentialto reflect POP contamination in that area. Few studies, however,have linked site characteristics to POP levels seen in marinemammals.5

The bottlenose dolphin is a particularly suitable species forexamining regional trends of environmental contaminants in U.S.coastal areas. The species is broadly distributed, inhabitingestuarine and near shore waters along nearly the entire U.S.coast.6 Stocks that remain within a given coastal area or estuaryyear-round are recognized from North Carolina southward onthe East Coast and along coastal areas of the Gulf of Mexico.6,7

Sampling of live bottlenose dolphins along the U.S. Atlanticcoast was previously used to identify geographic variations inPOP concentrations and patterns. Concentrations of polychlori-nated biphenyls (PCBs) in adult male and juvenile bottlenosedolphins were significantly higher in Charleston, SC and Beau-fort, NC relative to those in the Indian River Lagoon (IRL), FL.8

Polybrominated diphenyl ether (PBDE) concentrations werealso significantly higher in dolphins sampled near Charleston, SCas compared to those sampled in the IRL.9 Litz et al.10 observedthat similar POP variations in dolphins exist within a muchsmaller geographic area. Within Biscayne Bay, a coastal embay-ment adjacent toMiami, FL, resident bottlenose dolphins prefer-ring the more urbanized, northern part of the bay had signifi-cantly higher ∑PCB concentrations than animals preferring theless urbanized, southern portion of the bay. Likewise, dolphins

living near a PCB-contaminated site in southern Georgia accu-mulate a PCB signature characteristic of that site.11 Cumula-tively, these results suggest that bottlenose dolphins reflect theconcentrations of contaminants within their environment, andproximity to urban or industrial sources increases their POPexposure.

The current investigation greatly expands on previous efforts,integrating data from 14 independent studies with the goal ofimproving the understanding of factors influencing the concen-trations and profiles of POPs in coastal bottlenose dolphins tohelp prioritize future work on POP health effects on marinemammals in near shore environments. Collection and sampleprocessing protocols were standardized across studies, and allchemical analyses were conducted at the same laboratory,ensuring the comparability of results. The motivation for thiseffort stems from the observation that bottlenose dolphinsroutinely achieve POP concentrations in the tens or hundredsof parts per million and that POP concentrations of thismagnitude may impact bottlenose dolphin health.

’MATERIALS AND METHODS

Sample Collection. A total of 300 blubber samples from maledolphins were collected from 2000 to 2007 from 14 locationsalong the U.S. East Coast (n = 8 locations), the Gulf of Mexico(n = 5 locations), and from Bermuda (Tables 1 and S1 in theSupporting Information (SI)). Sampling locations ranged fromhighly urbanized estuaries (e.g., Tampa Bay, FL and northernBiscayne Bay, FL) to more rural sites (e.g., Sapelo Island, GA andwaters east of Apalachicola Bay, FL)(Figure 1). Animals sampledincluded those considered estuarine residents (estuarine stock),members of coastal stocks, or the Atlantic offshore ecotype(Table 1).6,7,10

Blubber samples were collected from live bottlenose dolphinsby dart biopsy10 or by surgical biopsy during dolphin healthassessment.12 Both techniques sample the full blubber thickness.Similar collection protocols utilizing solvent-rinsed instrumentsand Teflon storage containers were followed to ensure sampling

Table 1. Sample Size, Collection Method, and Lipid Content (%, Mass Fraction) of Blubber Biopsies Collected from MaleBottlenose Dolphins at 14 U.S. Atlantic and Gulf of Mexico Locationsa

sample type lipid (%)

location totals (n) surgical dart mean SD dolphin stock type population in adjacent countiesb

Bermuda 3 -- 3 50.0 10.2 offshore 64,200

Cape May, NJ 3 3 -- 51.5 2.0 coastal --

Beaufort, NC 2 2 -- 60.6 -- estuarine 230,600

Holden Beach, NC 3 3 -- 56.2 3.2 coastal and estuarine --

Charleston, SC 20 10 10 32.1 8.0 estuarine 558,100

Sapelo, GA 37 -- 37 22.0 9.8 estuarine 11,700

Brunswick, GA 38 -- 38 23.9 8.7 estuarine 127,400

Biscayne Bay, FL-North 15 -- 15 26.4 9.8 estuarine 2,446,900

Biscayne Bay, FL-South 15 -- 15 26.4 6.9 estuarine --

Sarasota Bay, FL 46 46 -- 36.7 16.5 estuarine 707,700

Tampa Bay, FL 5 -- 5 15.7 7.7 estuarine 2,125,800

Apalachicola Bay, FL-East 20 -- 20 30.4 7.4 coastal and estuarine 44,000

St. Joseph Bay, FL-West 38 5 33 32.3 11.9 coastal and estuarine 184,200

Mississippi Sound, MS 55 -- 55 29.2 6.3 coastal and estuarine 658,500a Location details are given in Table S1. bData are from the U.S. census Bureau (www.census.gov) and include population living in counties adjacent todolphin sampling locations (see Supporting Information).

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comparability.13 Following collection, field samples were frozenin liquid nitrogen vapor shippers and then transferred to�80 �Cfreezers for long-term storage until analysis.13 Sex was deter-mined from skin using molecular methods.14 Dolphin length andage were not available for dart biopsied animals and it wasassumed that sampling with respect to these two variablesoccurred randomly across the study. In addition, female dolphinsamples were not included as POP concentrations vary greatly infemales due to lactation loss and reproductive history wasunknown for the majority of female dolphins sampled.15

Persistent Organic Pollutant Determination. POPs inblubber were determined using methods described elsewhere10,15

and included pressurized fluid extraction (PFE), size exclusion,and alumina solid phase extraction cleanup followed by gaschromatography mass spectrometry (GC/MS) using two differ-ent capillary columns (see SI) and two different ion sources.Samples were processed in lots of 30�40 that included at leastone blank and 1�3 aliquots of National Institute of Standardsand Technology (NIST) Standard Reference Material (SRM)1945 Organics in Whale Blubber16 as a control sample. POPsdetermined in SRM 1945 averaged within 7.5% ( 3.5% ofcertified values.Statistical Analysis. Concentration data were lipid-normal-

ized and log-transformed prior to statistical analysis to meetassumptions of normality and equal variance. A multivariateanalysis of variance (MANOVA; JMP 7, SAS Institute, Cary,NC) was used to compare POP concentrations among locations;HCB, dieldrin, ΣPCB (sum PCB congeners in S2), ΣChlor (sumof cis- and trans-chlordane and nonachlor, oxychlordane, andheptachlor epoxide), ΣPBDE (sum of PBDE congeners 47, 99,

100, 153, and 154), and the ΣDDT (sum of 2,40- and 4,40-DDD,DDE, and DDT) were included as response variables andsampling location was the effects variable. ΣAroclor 1268 con-geners is the sum of PCB congeners 201, 180 þ 193, 207, 194,202, 187, 196, 199, 208, 209, and 206, which comprise, respec-tively, 0.6%, 0.9%, 1.8%, 2.7%, 3.0%, 3.0%, 7.1%, 9.1%, 9.9%, 11%,and 50% (mass fraction) of total PCBs in sediment adjacent tothe Aroclor 1268 Superfund site.17 Individual one-way analysis ofvariances (ANOVAs) followed post hoc by Tukey’s HonestlySignificant Difference (HSD) tests were then used to determinewhich locations were significantly different. Principal Compo-nents Analysis (PCA) using a correlation matrix was performedto investigate the variance of POP patterns among locations.Compounds with less than 75% detection were excluded fromthe PCA analysis, and values below the limit of detection werereplaced with 1/2 of the limit of detection. Concentrations wereconverted to a percent of total basis and mean centered to removeconcentration bias.

’RESULTS AND DISCUSSION

Comparison between Remote Dart and Surgical BlubberBiopsies. Blubber samples were obtained from 300 malebottlenose dolphins from 14 locations (Figure 1). Samples wereprimarily collected using dart rather than surgical biopsies(231 versus 69, respectively) (Table 1). Samples from twolocations, St. Joseph Bay and Charleston, were collected usingboth biopsy types prompting a comparison between the twocollection techniques. Lipid content (%) was significantly lowerin dart than in surgical biopsies from St. Joseph Bay dolphins

Figure 1. Geometric mean concentrations (mg/kg lipid) of Σchlordanes (ΣChlor), ΣDDTs, and ΣPCBs in bottlenose dolphin blubber.

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(Wilcoxon Rank Sum, p < 0.05); however, dart versus surgicalbiopsies from Charleston were not significantly different in lipidcontent. Concentrations of POP classes (Table 2), when ex-pressed either on a lipid or wet mass basis, in dart and wedgebiopsies from the two locations were not significantly different(Wilcoxon Rank Sums and t test, for St. Joseph Bay andCharleston, respectively). As a result, POP data from the twosample types were pooled for analysis.Ranges of Lipid and POP Concentrations. Lipid content

(% mass fraction) ranged from 3.4% to 62% in male bottlenosedolphin blubber. Blubber lipid content varied significantlyamong sites (ANOVA, p < 0.0001), with higher content inanimals sampled from Beaufort, Holden Beach, Cape May, andnear Bermuda than most other locations (Figure S2). Thevariation in lipid content among locations may be due tonumerous factors including ontogeny, nutritional status, andwater temperature.13,18 POP concentrations in blubber werelipid-normalized for among-site comparisons, and concentra-tions presented are lipid-based. Samples were collected in bothlate fall/winter and summer at Sapelo, Brunswick, Sarasota Bay,and St. Joseph Bay while all other sites had nonwinter collections.Lipid-normalized POPs were significantly lower (t test, p < 0.05)in winter versus summer samples at Sapelo, Brunswick, andSarasota Bay, therefore among-site comparisons excluded sam-ples collected in the late fall/winter.Lipid-normalized POP concentrations in bottlenose dolphin

blubber from the 14 locations are presented in Table 2 and inFigures 1 and S1. ΣPCB was the POP class present at highestconcentrations, with ΣPCB (geometric mean values are reportedthroughout; error is given in Table 2 as upper and lower 95%confidence limits) concentrations ranging from 33.1 mg/kg inbottlenose dolphins from east of Apalachicola Bay up to 450mg/kgin dolphins sampled from Brunswick (Figure 1; Table 2). Thehighest concentration observed was 2900 mg/kg in a dolphinsampled from Brunswick, a site heavily contaminated with thecommercial PCB mixture Aroclor 1268.19 The mean ΣPCBconcentration in the Brunswick dolphins was twice that observedin male transient killer whales from the Northeast Pacific Oceanthat have elevated POP concentrations due to marine mammalconsumption.20

ΣDDT was the compound class with the next highest con-centration ranging from 8.03 mg/kg in Biscayne Bay-south up to51.0 mg/kg in dolphins sampled near Cape May. In order ofdecreasing rank, concentrations of ΣDDT were followed byΣChlor, ΣPBDE, mirex, dieldrin, and HCB (Table 2; Figures 1and S1).Difference in POP Classes among Locations.Differences in

POP concentrations among sites were assessed in fewer loca-tions. Cape May, Beaufort, Holden Beach, and Bermuda wereexcluded due to small sample size (<5). All POP classes variedsignificantly by location. The most significant difference foundamong locations was for mirex (F = 45.5, p < 0.001, Figure S3).Mirex concentrations were significantly higher in dolphins fromBrunswick, Tampa Bay, Sapelo, Sarasota Bay, and MississippiSound than in other locations, except Charleston which wasintermediate between the two groups (Figure S3). Until 1978Mirex was heavily used in the Southeast U.S. primarily as aninsecticide for fire ant control although this compound was alsoused as an additive flame retardant from 1959 to 1972.21 Theamong-site difference may reflect past mirex use as an insecticideespecially on the fire ant, an invasive pest species in the Southeast U.S.T

able2.

GeometricMeanCon

centration

s(m

g/kg

Lipid

Mass)

ofPersistentOrganicPollutantsin

Bottleno

seDolph

inBlubber

from

14Lo

cation

sa

locatio

nn

HCB

mirex

dieldrin

ΣPB

DE

ΣChlor

ΣDDT

ΣPC

B

mean

L95%

U95%

mean

L95%

U95%

mean

L95%

U95%

mean

L95%

U95%

mean

L95%

U95%

mean

L95%

U95%

mean

L95%

U95%

CapeMay

30.12

0.06

0.25

0.23

0.10

0.53

2.22

0.82

5.96

6.56

3.23

13.3

9.03

3.83

21.3

51.0

22.5

115

139

62.8

310

Beaufort

20.038

0.02

0.09

0.38

0.13

1.09

0.82

0.24

2.76

1.46

0.61

3.47

2.48

0.87

7.11

20.9

7.68

57.0

43.3

16.3

115

HoldenBeach

30.084

0.04

0.18

0.17

0.07

0.39

0.87

0.32

2.33

3.65

1.80

7.41

4.18

1.77

9.86

16.8

7.39

38.0

57.1

25.7

127

Charleston

200.16

0.12

0.21

1.15

0.82

1.60

1.16

0.79

1.71

5.06

3.85

6.66

8.43

6.05

11.8

32.9

24.0

45.2

98.9

72.6

135

Sapelo

300.053

0.04

0.067

2.42

1.80

3.25

0.16

0.13

0.21

3.98

3.10

5.12

6.16

4.52

8.39

26.3

19.57

35.4

170

126

229

Brunswick

190.055

0.04

0.075

2.89

1.94

4.30

0.41

0.30

0.57

3.61

2.85

4.57

4.97

3.90

6.32

26.1

18.9

36.1

450

307

658

BiscayneBay

-North

150.037

0.03

0.05

0.16

0.11

0.23

0.52

0.34

0.81

2.36

1.72

3.24

6.35

4.33

9.32

15.9

11.1

23.0

157

110

224

BiscayneBay

-South

150.016

0.01

0.02

0.09

0.06

0.14

0.15

0.10

0.24

0.87

0.63

1.19

1.85

1.26

2.71

8.03

5.57

11.6

33.7

23.6

48.2

SarasotaBay

330.086

0.07

0.10

1.96

1.37

2.81

1.59

1.24

2.05

1.91

1.59

2.29

23.0

17.7

29.9

36.5

26.9

49.7

71.6

54.1

94.7

Tam

paBay

50.024

0.01

0.05

2.72

1.40

5.28

0.97

0.45

2.09

1.43

0.83

2.48

16.6

8.54

32.3

28.4

15.1

53.5

109

58.9

203

Eastof

ApalachicolaBay

200.032

0.02

0.04

0.63

0.46

0.88

0.17

0.12

0.26

0.69

0.53

0.91

2.74

1.97

3.82

23.3

17.0

32.0

33.1

24.3

45.1

St.JosephBay

380.034

0.03

0.04

0.55

0.43

0.70

0.20

0.15

0.27

1.47

1.21

1.80

2.74

2.15

3.48

34.4

27.3

43.2

63.0

50.4

78.9

MississippiSound

550.080

0.07

0.09

1.49

1.22

1.82

0.55

0.43

0.69

3.78

3.20

4.46

4.70

3.85

5.75

38.4

31.7

46.4

68.0

56.4

81.9

Bermuda

30.24

0.12

0.51

0.62

0.26

1.45

0.15

0.06

0.41

1.66

0.82

3.37

5.16

2.19

12.2

30.9

13.7

70.1

38.8

17.4

86.1

aL9

5%andU95%arethelowerandupper95%confidencelim

its,respectively.

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Dieldrin varied significantly by site (F = 33.9, p < 0.001,Figure S4) and was higher in dolphins sampled from Sarasota,Charleston, and Tampa Bay relative to most other locations(Table 2, Figure S5). Dieldrin and aldrin (a dieldrin precursor)were broad spectrum pesticides that were used extensively in theU.S. withmajor applications including termite control in additionto use in corn and citrus production.22 Residues were detected insoils and air from the Southeast U.S. 23 and in bivalve tissues fromGulf of Mexico and Northeast U.S.2 Dieldrin and aldrin have notbeen produced in the U.S. since 1974, however, aldrin wasimported until the mid 1980s.22

∑PBDEs also varied significantly by location (F= 28, p< 0.001,Figure S5). The highest ∑PBDE concentrations were observed indolphins from Cape May (Table 2, Figure S1); however, thisgroup was not included in the statistical comparisons with theother geographic areas due to small sample size (n = 3). Of thesites compared, concentrations were highest in dolphins fromCharleston, Sapelo, Mississippi Sound, and Brunswick. Concen-trations at these sites were significantly higher than concentra-tions measured from Sarasota Bay, St. Joseph Bay, Biscayne Bay-south, and east of Apalachicola Bay (Table 2, Figure S6). Othersites had intermediate concentrations relative to these twogroupings. PBDE formulations are extensively used as an additiveflame retardant in numerous products.24 PBDE sources to themarine environment are varied and include introduction viasewage outfalls.25 The uses of PBDEs suggest that estuaries nearurban centers such as Biscayne Bay-north nearMiami would havehigher ∑PBDE concentrations than rural sites, however this wasnot observed in this study. Sapelo dolphins were included in thegroup with significantly higher ∑PBDEs, whereas the Sapeloestuary is situated in a rural location. These results suggestbroader scale contamination by PBDEs possibly from atmo-spheric deposition.The next most significant among-site difference was observed

for ΣPCB (F = 27, p < 0.001, Figure S4). ΣPCB concentrationswere significantly higher in bottlenose dolphins from Brunswick(mean 450 mg/kg) than all other locations. Dolphins fromSapelo had next highest PCB concentrations (mean 170 mg/kg),however the ΣPCB concentration in this group was not sig-nificantly different from those of dolphins from Biscayne Bay-N,Tampa Bay, or Charleston (Table 2, Figures 1 and S6). ΣPCBconcentration in dolphins from Biscayne Bay-south and east ofApalachicola Bay exhibited the lowest mean concentrations of allsites at 33.7 and 33.1 mg/kg, respectively.ΣChlordane concentrations were highest on the central west

coast of Florida (Sarasota and Tampa), followed closely byCharleston and Biscayne Bay-north, Brunswick, and Sapelo(Figures 1 and S8). ΣChlordane concentrations from these fourlocations were significantly higher than concentrations in St.Joseph Bay, Apalachicola Bay-east, and Biscayne Bay-south. Allother sites were intermediate. Chlordane was used in the U.S.until 1988 primarily in house foundations to prevent termites.26

From 1978 to 1988 chlordane was registered for only this use inthe U.S. The higher concentration of chlordane observed indolphins from urban estuaries in the Southeast U.S. likely resultsfrom past use to control termites. For other marine indicatororganisms, such as bivalves, chlordane concentrations werehighest near urban areas in the Southeast U.S.2 Chlordane canreadily volatilize from application sites27 and therefore has thepotential to contaminate nearby estuarine water bodies.HCB concentrations were highest in dolphins near Charleston

(mean 0.16 mg/kg) (Table 2 and Figure S7). Concentrations

from Charleston, Mississippi Sound, and Sarasota Bay weresignificantly higher than those from other locations with theexception of Brunswick and Sapelo. Relative to the other POPsexamined in this study, HCB is relatively volatile, persistent, andwas observed to be rather homogeneous in the North Americanatmosphere.28 This suggests that in the absence of local pointsources, HCB concentrations would be invariant in dolphinblubber; this was not observed in this data set. The higherconcentrations in dolphins from Charleston, Mississippi Sound,and Sarasota study suggest the existence of local HCB sources(Figure S7).The highest concentrations of ΣDDT were measured from

Mississippi Sound dolphins but pairwise differences between thislocation andmost other locations were not statistically significant(Figures 1 and S9). Concentrations measured from both Bis-cayne Bay sites were significantly lower relative to other loca-tions. The use of DDTwas banned in the U.S. in 1972,29 howeverDDT compounds are still frequently detected in the marineenvironment. Interestingly, the highest DDT/DDE ratio (0.11)was observed in dolphins sampled from near Bermuda. This wassignificantly higher (F = 15.4, p< 0.001) than the ratio from otherlocations and was 4.4 times the next highest mean ratio of 0.025observed in Charleston. The ratio of native DDT to its primarymetabolite, DDE is often used as an indicator of recent insecti-cidal DDT input.30 The high DDT/DDE ratio in Bermudadolphins suggests recent input of DDT into the Bermuda foodweb, perhaps from long-range atmospheric transport of DDTfrom Africa, where DDT is still used for malaria control.31

Factors Influencing POP Profiles and Concentrations. Toexplore the relationship between location and POP profiles,principle components analysis (PCA) was used. The first threeprincipal components (PC) accounted for 34%, 12%, and 10% ofthe data variance, respectively. PC 1 clearly demonstrates thedifference in POP profiles in the Brunswick and Sapelo dolphinsas compared to other locations (Figure 2). The PC 1 scoresvaried significantly by location (ANOVA, F = 194, p < 0.001). Asillustrated in the PC loadings plot (Figure 3), negative loading on

Figure 2. (A) Principal components correlation matrix biplot. Theabbreviations are as follows: APA = Apalachicola Bay-W, BER =Bermuda, BB-N = Biscayne Bay-N, BB-S = Biscayne Bay S, BEA =Beaufort, BRU = Brunswick, CHS = Charleston, HOL = Holden Beach,MIS = Mississippi, NJ = New Jersey, SAP = Sapelo, SAR = Sarasota,SJB = St. Joseph Bay-W, TB = Tampa Bay. Brunswick and Sapelosamples are labeled in red and blue, respectively.

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PC 1 was greatest for high molecular weight PCB congeners thatare predominately associated with Aroclor 1268 commercialPCB formulation.32 The Turtle/Brunswick River in the Bruns-wick, GA estuary is contaminated with this unique PCB mixture,and the Aroclor 1268 signature was detected in sediments andother components of the estuarine food web collected from thislocation and this PCB mixture has been documented in bot-tlenose dolphins from this region in smaller studies.11,33,17,34 Theprevalence of the Aroclor 1268 signature in Brunswick/Sapelodolphins is more obvious when the ratio of ∑Aroclor 1268congeners to ∑PCB is compared among locations (Figure S10).As expected based on the PCA results, the proportion of Aroclor1268 in Brunswick and Sapelo dolphins was significantly higherthan other locations (F = 522, p , 0.001). The Sapelo dolphinswere sampled in and around the Sapelo Island National EstuarineResearch Reserve (NERR) which is located approximately 50 kmnortheast of Brunswick, GA. The presence of the Aroclor 1268signature in the Sapelo dolphin population suggests movement ofcontaminated prey and/or dolphins between these two areas.35

Principal component 2 accounted for less of the total datavariance (12%) and obvious separation of the samples based onlocation was not as evident relative to PC 1 (Figure 3). The mostsignificant negative loadings on PC 2 were PCB congeners 180,176, 151, 177, 174, 149, 185, 137, 138, and 128; these PCBcongeners are characterized by their high bioaccumulationpotential and resistance to metabolism especially in cetaceansas they are multiply chlorine substituted in the ortho position(Figure 3; refs 15 and 36). In comparison, the highest positiveloadings on PC2 were for PCB congeners 66, 56, 44, 74, trans-chlordane, PCB 105, and dieldrin. All of these PCB congeners,with the exception of congener 44, are mono-ortho chlorinesubstituted and metabolized by dolphins. Similar results indicat-ing variation in the recalcitrant PCB congeners were attributed todifferences in dolphin age.8 Age-related variation could not beexamined as age was unavailable for dart biopsied animals. Thechlordane compounds and dieldrin also had high positive load-ings relative to other compounds driven mainly by high con-centration of these compounds relative to other POPs in theSarasota Bay dolphin population.These results demonstrate concentrations and mixtures of

POPs in bottlenose dolphin groups vary with POP sources and

metabolism. The effect of industrial POP sources is clearlyevident in the high proportion of octa- through decachlorobi-phenyls in dolphins sampled near Brunswick and Sapelo. Thisunique PCB signature has been linked in prior studies to the LCPChemical facility located on Purvis Creek in the Brunswickestuary.11,19 The toxicological significance of this highly chlori-nated PCB mixture in these dolphins is unclear. At least somePCB toxicity is manifested through the generation of phenolicmetabolites that interfere with thyroid hormone regulation.37

Total hydroxylated PCBs in dolphin blood can be present atconcentrations of up to 68% that of ΣPCBs, however themajority of hydroxylated PCB congeners reported in dolphinblood from other areas contain only 3�5 chlorines.38 Generationof high relative proportions of hydroxylated PCBs in the dolphinsfrom Brunswick and Sapelo is mechanistically unlikely due thehighly chlorinated nature of their PCB mixture.37

None of the POP classes determined in this study weresignificantly correlated with the human population living incounties adjacent to the study sites (Table 1). However, PCB153 which is highly bioaccumulative and generally indicative ofnon-Aroclor 1268 PCB formulations, was significantly correlatedwith human population (r2 = 0.79, p < 0.001). PCB 153 is ahighly recalcitrant and important congener in non-Aroclor 1268PCB formulations primarily used in electrical equipment. Thusdolphins living adjacent to urbanized areas should have highernon-Aroclor 1268 concentrations relative to other locationswhich is supported by higher PCB concentrations in the BiscayneBay-north and Cape May groups (Figure 1). In the case of theother POPs, factors driving regional variability are not clear andare probably more driven by application patterns particularly inthe case of pesticides.This study also demonstrates that the magnitude of POP

contamination varies considerably from site to site (Figures 1and S1). It is also important to point out that food web variabilityas a function of location may in part drive the POP concentrationvariance in dolphins. Dolphins within similar areas may partitionwith respect to foraging location such as between seagrass andnearshore environments.39 Fish assemblages may differ slightlyamong the coastal areas examined in this work. The effect ofdolphin foraging behavior and fish assemblage changes ondolphin contaminant patterns and concentrations, however, islikely to be less important than differences resulting from local orregional POP contamination. This is supported by differencesseen in locations with adjacent sampling, such as Biscayne Baywhere dolphins likely have similar forage bases yet significantlydifferent POP concentrations. However, this influence should beaddressed in future work attempting to explain difference in POPconcentration as a function of location by including trophic levelindicators such as fatty acids or stable isotopes.Because dolphin POP concentrations vary with location the

health effects stemming from POP exposure likely do as well.Recent work demonstrates that health impairment occurs inbottlenose dolphin groups with highest POP exposure relative toother groups.40 In dolphins from the Sapelo and Brunswick sites,total PCBs were significantly correlated both to circulatingthyroid homones (free T4) and functional immune responsethereby demonstrating that the POP concentrations observed inthis study have direct impacts to dolphin health. This study alsoshows that legacy POPs, while generally banned or phased out ofproduction, are still pervasive threats to marine animal health.The health effects of POPs on bottlenose dolphins will likely beprolonged as dolphins will respond only slowly to declining POP

Figure 3. PC loadings plot of the relative abundance of POP com-pounds in bottlenose dolphin blubber. Aroclor 1268 congeners are inred (see Materials and Methods for list).

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concentrations in coastal waters as shown for killer whales livingalong the North American West Coast which are also highlycontaminated with legacy POPs.41

’ASSOCIATED CONTENT

bS Supporting Information. This material is available freeof charge via the Internet at http://pubs.acs.org.

’AUTHOR INFORMATION

Corresponding Author*E-mail: John.Kucklick@noaa.gov.

’ACKNOWLEDGMENT

Funding was provided by the National Marine FisheriesService (NMFS), Disney Wildlife Conservation Fund, DolphinQuest, the Chicago Zoological Society Sarasota Dolphin Re-search Program, and by a grant awarded from Harbor BranchOceanographic Institution, Inc. from proceeds collected from thesale of Protect Wild Dolphins License Plate as authorized byFlorida Statute 320.08058(20). We thank the field personnel andveterinarians who were involved in these projects. Certaincommercial equipment and materials are identified in this paperto adequately specify the experimental procedure. Such identi-fication does not imply recommendation or endorsement byNIST, nor does it imply that the materials or equipmentidentified are necessarily the best available for the purpose.

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