EC~YPTIIZN JOURNAL 01: AQlJATlC RESEARCII V01.. 34 NO. 4,2008: 126-142

RESPONSE OF SCLERACTINIAN CORALS TO THE NATURAL AND ANTHROPOGENIC HEAVY METAL STRESSES IN THE

NORTHERN RED SEA AND GULFS OF SUEZ AND AQABA

MAHMOUD A. DAR*; ABD EL-HAMID A. ALI AND FEKRY A, MURAD

National lnstitlrte of Oceaito,qrophy and Fisheries. Red Sea Branch, Egypt. * E-niciil: mnhmoud~rnd~~(@yahoo.com

Keywords: Scleractinian corals, antkropogenic stresses, Red Sea, Suez and Ayabn.

ABSTRACT

'I'he heavv metal contents were studied in the bleached and non-bleached snecimens of six species of branching, encrusting and masive corals collected liom the norlhern Red Sea (Iiurghada); Suez Gulf (Zafraua and Ain Sokhna) and along the western side of Aqaba Gulf (sham1 El-Shcikh, Oahab and 'i'aba). The areas of investigation are highly subjected to the anthropogenic strcsscs. Zn. f'c, Pb and Co recorded significant averagc concentrations in thc differcnt spcci~ncns at the different localitics while Cu was insignificant. Massive corals as Lopopliylliu corvti~bosu, Porita lirlea and GuLnia fnsinrlrzt~is showed significant high metal concentrations in the different localities followed by the encrusting and branching Echinopow gemmuceu. Northern Red Sea recorded the highest average Zn content (21.30*13.74jtg/g) in the non-bleached corals and Pb (17.64i14.19 pglg) in the bleached corals that may attributed essentially to the tourist activities and the related industries as; coastal constructions, desalination plants, automotive boats and shipyards. Gulf of Sucz rccorded the highcst averages of l'e in thc non-bleached and bleached specimens (38.98119.98 pg/g; 41.46k25.53 pg/g respectively) that may indicate that the terrestrial intilling from flash tloods, dusty winds andlor coastal enhancements ale thc main sources of heavy metals in the gulf The high Pb in the non-bleached corals (16.67+6.40 pdg) of Suez Gulf is due to oil terminals, industrial wastes, fishing and maritime activities. Aqaba Gulf recorded the highest average of Co in the non-bleached and bleached specimens (5.291t2.02 and 6.46k1.74 pg/g, respectively) and Zn in the bleached specimens as well as relatively high concentration for the other mctals that may be due to industrial activities, sewage spills and military activities at the northern tip of the gulf.

1. INTRODUCTION

The Red Sea coinprises a wide range of marine habitats, many of which are internationally recognized for their conservation, scientific, economic or rccrcational value (Dicks, 1984). The Red Sea is considered a Coral Sea because of its topographical and climatic conditions are quite exceptional, it has narrow and shallow connections to the ocean that allow limited exchangc of surfacc watcr (Mcrgncr, 1984). The most conspicuous shallow water marine habitat in the Red Sea is formed by extensive

coral reefs which fringc much of ~ h c coastline and often extend offshore for many kilometers (UNEI', 1985). Mostly they are narrow, cxtcnding only a few tens of meters fiom the shore, while in an areas, further south, the fringing reefs commonly extend 1 km seaward. Coral cover in the northern Red Sca is usually less than SO%, but in sheltered arcas one or two spccies espccially Porites, cover 80% of the substrate. The complexity of the ecosystem is illustrated by its high diversity, approximately 250 species of stony corals and 180 spccics of soJt corals may be found in the Ked Sea (Sheppard et ul., 1992).

Suez Gulf extends for about 255km with widths of 17-25hn and maxiinuni depth of 83111. In general, reef health was considered good, with 30 to 50 % live coral cover at most locations and more than 50% total cover on average (PERSGNGEF 2003). Reefs on the western side of the Gulf of Suez are better devclopcd in general than those on the east. At Ein Sukhna, the reef flat extends 30-40m offshore and is followed by gentle slope to a sandy bottom at 4-5m depth. The outer slope supports flourishing coral growth with up to 15 genera dominated by Porifes, Acropora and Stylopltoru ((Rehairy et al., 1992).

The Gulf of Aqaba is short, narrow and much deep. It extends for 180km nith widths varying from 25kn1 in its southern part to 16km at the north. 'l'hc maximum water depth reaches up to 1850ni in the central basin (Fouda and Gerges, 1994). Gulf of Aqaba represents the most northerly reefs of the cntire Indian Ocean. In most of the Gulf of Aqaba, only a narrow fringing reef finds a foothold on tlie steep cliffs. The coral reef system of the Gulf of Aqaba supports an exceptional biodiversity, and is particularly vulnerable to the effects of pollution due ro its low rate of water exchange with the main body of the Red Sea (Wielgus et al., 2004).

Coral reefs are among the most vulnerable ecosystems in the world (Scott and Davies, 1997). Disturbances such as bleaching, fishing, pollution, waste disposal, coastal development, sedimentation, SCUBA diving, anchor damage, predator outbreaks, illvasive species and epidemic diseases have all acted synergistically to degrade coral reef health and resilience. Today, an estimated 20% of coral reefs worldwide have been destroyed, while 24% are in imminent danger and a further 26% are under longer term danger of collapse (Wilkinson, 2004).

Heavy metals such as cadmium, mercury, lead, copper and zinc are regarded as serious

pollutants of aquatic ecosystems because of their environmental persistence, toxicity and ability to be incorporated into food chain (Forstner and Wattman, 1983). Their concentrations in the hard corals have been used as environmental monitor for the different natural and anthropogenic eflluents in the coral reefccosyst~m (Scott and Davis, 1997; Bastedas and Garcia, 1999; Fallon et a/., 2002; b m o s el al.. 2004), for their role in the coral growth (Esslemont et ul., 2000; Reichelt-Brushett and McOrist, 2003; Ferrier- Pages et al., 2001, 2005), as well as their role in the coral skeleton density and structure (Sholkocit7 and Shen, 1995; Ino~le et al., 2004; Ammar et ul., 2005).

The present study compares the heavy metal contcnts between thc northern Red Sea, Sucz (hl f and (jutf of Aqaba coral reefs to identify the effective pollutant sources in each locality as well as the differential abilities of the l~cavy metals to introduce thc skeletal structure of corals or reject to the surrounding environment.

2. MATERIALS AND METHODS

2.1. Field works

Six specimens of three hard coral forms (branching, massive and encrusting) were collected from the northern Red Sea (Hurghada), Suez Gulf (Ain Sokhna, Zafarana) and from three localities along the western side of the Gulf of Aqaba (Taba, Ilahab and Sharm Al-Sheikh) (Fig. I). Thc collected specimens were identified according to Sheppard and Sheppard (1 99 1) and Vcron (2000). They are; Echinopora gentniacea (branching); lichinopora gemmaceu (encrusting); Lopophyllia coiymbosa, Gulaxiu fusicularis, Porites hitea and Fubliu sp. (massive).

RLSPONSL 0 1 SCLLKAC'I INIAN C'OIIALb 1 0 l l lL NI\ l LllIAL AND 4'4 I IIROPOGLNIC IILAVY ML l,\L STRESSFS IU T11F NORTI-IFRN RFD (FA 4 N D (1111 FS OF 5lJr7 A N D A Q A R 4

Fig. (1): Location map.

2.2. Analyses

The freshly collected specilllens were washed gently with distilled water. Each specimen-was sliced into two parts; one part of each specimen involves the overlying organic matrix (mucus, tisst~e and zooxanthallae) was fixed with fonnalin (6%- analytical grade) for 48hrs then oven dried at 60°C for another 48hrs. After drying, these parts were powdered in agate mortar to less than 80 incshcs to approach the coinplctc hon~ogeneity .

The overlying organic matrix of sccond part of each specimen was bleached completely using analytical grade ~nixture of 15% sodium hypochlorite and hydrogen peroxide (Esslemont et a/., 2000; Dar, 2004). The bleached specimens were powdered in agate mortar to less than 80niesh. One grain of powdered samples (bleached and non- bleached) were digested with 1 Om1 of cone. HN03 to near dryness (Chester et a/., 1994) and then dilt~ted to 251111 with deionized distilled water.

The resultant solutions were used to detemn~ine; Fe, Zn, Cu, Pb and Co contents in the non-bleached and bleached parts of the sclected coal reef species using Atomic Absorption Spectrophotometer (GBC 932, Ver I. I ). The measurements were expressed as pglg and the accuracies were obtained by applying three rcplicatcs in each tncasurement with reading variation less than 5%.

3. RESULTS AND DISCUSSION

Extensi~e coral mortality in the Red Sea and most of the tropical and sub-tropical regions can be attributed to natural stresses such as coral bleaching. catastrophic low tide events and storms (Perkol-Finkel and Benayahu, 2004) as &ell as additional stresses in the Soml of terrestrial runoff, pollution, coral mining, and recreational activities, which threaten the very existence of coral reefs ((Clark and Edwards. 1995; IIawkins et ( I / . , 1999). These hctors rcduce the reef resilience and ability to recover m the

face of further natural or man-made catastrophes (IIughes and Connell, 1999).

I feak y inctals are amongst thc most serious pollutants n ~ t h ~ n the natural etivtronlnents due to their toxic~ty, persistence and bioaccuniulat~on problems (MacFarlane and Burchett, 2000). Shen and Uolle (1987) and Shen et ul. (1987) claim that metal\ ~ e h as lead and cadm~iml bound into the aragonit~c latticc of the skeleton may be sensit~ve ~udicators of the d~ssolved inelal content of the surrounding ocean waters, and conscrlueitly prov~de evidencc for natural phyGcal and biolog~cal proccsws as mcll as anthropogen~c discharges.

At IIurghada in 1he non-bleached spccimcns: Porites Iutca sccordcd the highest Zn content (45.53 pdg) followcd by the. cncrusting I<ch i~~r~p~~ra genznzacia (27.60 pdg). The h~gl~es t Fe contents were recorded in Loyoplldlicr cog,nlbostr (58.91 pglg) followed by Porltc:~ l ir te~ (3 1 .89 jlg/:/g). The highest Pb wcrc recorded in Echino~pora genmtlclcr (19.63 pglg) followed by 1'orlte.r luterr.

In the bleached specimens; Lopoph~dhu coi:vn~hosa recorded the highest Fe (52.04 k~glg) and the highcst 1% contents (45.03 pglg) follo\\ed by the branching Fchinoporu gerritnuc.iu (47.5 1, 14.8 1 pdg, respectively). The highcst Zn recorclcd in the bratlchmg Iichlnopora genzmucia (19.85 pp/g) followed by Porzie.t Itrtca. (;alaxia fi~\ic-uhri.t recorded the highest Co content (8.62 pglg) followed by encrusting Echinoporu gerriniuc,ta (Fig. 3).

In general, the coral species of the 11orthe1-n Red Sea recorded high Zn contcnts in the non-bleached specimens than in the bleached specimens, whtle Pb and Co recorded h~gh conccntratlons in tht: blcachcd than the non-bleached spccimcns ('Tables 3&3). This is indicating to the bioaccumulation tendency of Pb and C'o in the skeletal lkaillework oF corals in thts location more than the others. The high tnclal contcnts in the coral colonies in nlany areas in Hurghada are due to direct supplying sources of pollutants mainly from the antifouling paints and repairing rusts of s h ~ p

maintenance, the reject \\ater of desalrnat~on plants as \veil as the boats mooring near ant1 oter the coral con~mun~lics as tncnt~oncii by (Madkonr and Dar, 2007) as well as the existed landfill operations from the coastal constructions and beach enhancements that reducing the reef growth rates and destroying the coral colotlies by hcavy suspended loads and the macro-algae o\crgrowth duc to nutrient enrichments (liar, 2004; Ilar and Mohamed, 2005). These inipacts affect tlirectlq the health and state of the corals, with ttme these coral species are habituated to thcsc strewe5 and their ahillties to as\ini~latc these strange materials inside their skeletons are increasing proport~onally with d~fferent~al assinnlation ability from species to another.

,4t Ain Sokhna, Gllaxia fbsic-u1uri.s recorded the highest Zn (16.39 pglg) and the highest Fe (67.34 pglg) in the nou-bleached specimens. Porltrs lutrrt recorded thc highest Pb and Co (26.85. 7.44 pg'g) rcspcctively. In the blcached specimens, (;alaxm jirsiru/ur~.t recorded the highest Fe (95.55pglg), Echrnoyoru grnzmacia recorded the highest Zn (15.32 &g), firwr~ sp. recorded the highcst Pb and Co (20.08, 7.23 pp'g) rcspcctively. The recorded metals values in Por~tes lutecr at Zafarana local~ty are lower than those at ~Zin Sokhila (Fig. 3). Ilamed and El-Moselhy (2000) attributed the high metal concentrations in the coastal waters of Suez G11lf to the sewage discharge, garbage from city itself and sh~ps and the waste effluents from thc industrial con~plexes as; oil refiners, fertilizer plant, power station and other ~ndustries along the gulf. They also recorded that the metals concentrat~on in the seawater at Ain Sokhna IS relatively low and the oil p0llut1011 is evident in the vicinity oSSUMED pipelines terminals which includes both float~ng and land based reeeiv~ng terminals while the average concentratlons of trace inetals at the southern part of the Gulf of Suet were slightly high may be due to the presence of a huge numbers of petroleum fields with hcavy burden of metal pollution and the metal sedimentation results f'rom the

KLSPONSC 01: SCLbllACI INIAN COR.4LS IO I Ilk Nz2 I URAL AND AN I IIKOPOGkNIC l ILAVL MLl'AL CTRFSSES Ih THF NORTIlFRN RFD SEA ANT) GI11 FS OF (IIE7 AND AQARA

exchange of water between Red Sea and Suez Gulf.

Table (1): Heavy metal contents, the average and the standard deviation in the non- bleached and leached coral species in the northern Red Sca, Suez and Aqaba gulfs.

K 2

", ,& - ,? V

'c r -

a

c o r ~ ~ t ~ t h o . ~ ~ ~ <iclltruitr ,JilF~clrluri.s

Porite.~ Iuteu

F(11qilr sp.

i'orilcs Iule(1

Av

St. D. Echino. gernntnceu (En) LopophyNicr cor;vntho.str Echino. gc?a~macc?o(I:n)

rg;i;y ' I>or.itc<~s /~rtc>u

(Sharni) - -

Av

St. I).

41.25

67.34

3.07

24.44

51.75

38.08

19.98

2.36

41.34

35.11

26.53

18.15

24.70

13.04

13.56

16.39

15.67

8.36

15.28

12.77

3.00

20.49

17.69

4

8.22

11.56 --- 15.17

4.08

17.29

11.25

26.85

21.35

17.45

10.67

6.40

22.7

3.95

1.78

5.86

16.15

2.79

1.11

0.32

0.95

0.36

1.70

1.25

2.84

1.26

2.88

0.57

0.72

10.0'9 33.98

8.00 1.01 2.02 6.1 1

4.26

2.30

0.91

7.44

4.37

3.08

2.22

3.09

4.16

5.33

9.05

4.83

12.09

. 1.44

95.55

56.26

9.97

27.03

37.33

41.46

25.53

19.97

35.77

38.4')

41.34

24.33

11.30

4.43

9.45

9.62

14.82

10.63

11.70

11.43

2.42

11.15

10.63

1 . 0 0

13.21

14.35

1.16

0.42

9.5

10.54

14.1 1

20.08

16.84

13.64

4.83

11.30

17.20

14.33

4.14

9.55 ----- 6.46

1.74

2.05

0.92

0.21

0.51

0.12

0.78

0.60

0.91

1.25

0.67

1.04

1.91

2.44

2.32

5.78

7.23

6.08

3.98

2.23

6.74

9.57

4.64

6.30

5.04

'Fable (2): The average concentration of the heavy metals in the bleached coral specimens in the different locations in comparison with some other studies in the locality and around the world.

Poriies Corals

...... -- - - -

Purifc.s Sa-2001

ItbSPONSl? 01. SCtbKAC I INIAN COR.r\LS 1 0 I Ilk NA l UKAL AND AN I IIKOPO(;bNIC iILAVY Mb'l'AL STRFSSES IN TlfF NORTIlFRN RFD SE4 A N D G111 FS OF (IlFi! A N D AQARA

Table (3): 'l'he average concentration of the heavy metals in the non-bleached coral specimens in the different locations in comparison with some other studies in the locality and around the world.

Echinopora Echinopora Lopophyllia Galaxia Porites gemmacea gemmacea corymbosa fasicularis lutea

(Br) (En)

N-Red Sea (Bleached corals) 60

Fe

Echinopora Echinopora Lopophyllia Galaxia Porites gemmacea gemmacea corymbosa fasicularis lutea

(Br) (En)

Fig. (2): Heavy metal distributions in the non-bleached and bleached corals at N. Red Sea.

KLSPONSE 01' SCLbiZACl INlAN COIZALS 10 I l i b NA l URAL AND AN1 IIROPO(;LNIC tlL,\VY M b l AL STRFSSES IN TlfENORTI1FRN RFD S F 4 ANT) GI11 FS OF 5( iE7 AKD AQABA

Suez Gulf (Non-bleached corals)

Echinopora Echinopora Lopophyllia Galaxra Porites Favia sp. Porites gemmacea gemmacea corymbosa fasiculans lutea lutea

lBr) (En)

Suez Gulf (Bleached corals)

Echinopora Echinopora Lopophyllia Galaxia Porites Favia sp. Porites gemmacea gemmacea corymbosa fasicularis lutea lutea

Fig. (3): Heavy metal contents in the non-bleached and bleached corals at Suez Gulf.

According to Wilkmson's class~fication, the coral reefs of the Gull' of Aqaba arc among the most deterlorated and considered to be in cr~tical ctatus; where 'critical' is defined as 'reefs that are severely damaged and 111 ~mminent threat of collapse or cxtcnnination unless the current levels of anthropogenic stress arc rcmovcd or ameliorated' (W~lkinqon, 1997). In thc non- bleached spec~es of the Gulf of Aqaba localities, Echzrtoporrr gt~~n~ntrcitr recorded the highest Ln and Pb (90.49, 22.7 pg/g) while I,opop/xyll~~ ~(~rj~nlhoscr rccordcd the highest Fe (4 1.34 p d g ) at Taba. Por~tc.~ lulecr recorded the h~ghest Co content (0.05 p g g ) at Dahab.

In the bleach speclcs; Porttes lutea recorded the highcst Zn (14.35 kcgig) at Sharm Al-Sheikh and the h~ghest Fe content (4 1.34 ~ ~ g / g ) at Dahab. Lopophj 111a co/;vmbosa recorded the highest Pb ( 1 7.20 @g) and Co (9.57 pg/g) at Taba (Fig. 4). The recorded ('u values in tlie d~fferent species and localit~es were ~nsignificant.

The studled coral species in Gulf of Aqaba locations show high Fc, Pb and Co concentrations in the bleached than in the non-bleached specitnen, \vliile Zn content Nas varizble between the bleached and non- bleached specimens (between 8.22 and 20.49pgIg in the not:-bleached spcclmcns and betueen 10.63 and 14.35pgg In the bleached specimens). The corals along both s ~ d e s of Aqaba Gulf hale been exposed for years to ctivcrsc anthropogenic disturbances, such as rn~micipal sewage d~scharges ((;hobaslly and Kotb, 7001), the sp~llage of phosphate dust during loading of phosphate mineral onto ships (U'alkcr and O t l o n d , 1982; Abelson et 01. 1999), to thc anthropogcnic inipacts of SCIJHA divers and the high sed~rnentation rate (Wielgus el (11, 2004) intens~ve martculture, recreat~onal diving pressure, increased sedimentation due to marine constn~ction, and diverse n~ar~t i tnc activities (Zvuloni PI ul., 2008; Hen-T7~i ct trl, 2004). Abu llelal (1003) and Abel3on c.1 crl (1999) attributed the heavy metal pollullon in the

northern Gulf of Aqaba to the freshly deposited phosphate ra\% powder, port activ~ties and \ewage effluents dulnped from the main sewage plant while Hatned and El- Moselhy (2000) attr~buted the Izigh concentrations oT; Fe, Cu, Zn, Pb and C'o m the scawaters at Taba, Nuwclba and Sham: AI-Shc~kh harbours to the water d~scharge from s h ~ p s and tourlst ccntcrs and other human activltles. Al-Moghrabi (3001 ) recorded the Grst case of the coral disease l 'o~~nd 011 Gonioporn southern the shore of Jordan and some other mfectcd spcc~cs (C;onropoi.u, Allleoporu glgus, A~treopot-u avrlophthcrlrncr, ~ ~ l o n ~ r p o r u verr-~cc.o~a and Echinoyhjdliu ~ s p e r a ) . IIc attributed the coral disease mfcction to the industr~al pollution that has synerg~stic irnpact u ith temperature. Al-Rousan et ul. (2007) po~nted out; most of Ilea\ y metals s h o ~ c d dramal~c lncrcase (rangmg li-om 17 to 300%) in growth band sectlolls of Porrtes younger than 1965 in lordan~an Gulf of Aqaba suggesting an estenslve contamination of the coastal area since the mid sixties wtth the huge increasing of the coastal activities, cot~structions and urban~zat~on producing s~gniticant reduction in coral skeletal extension rates. They &ere ind~cateil that Pontc.., corals have a h ~ g h tendency to accunlulate hemy mctals in t h c ~ r shclctons and therefore can sel \c as proxy tools to Inonitor and record env~ronnlental pollut~on (b~omd~cators) m the Gulf of Aqaba.

In add~tion to the anthropogcn~c stresses on the bcnth~c corals at Aln Sokhna, Zaafrana and all the studled local~t~es along Gulf of Aqaba, these areas are temporarily threatened by natural floods. The Llood loads attack the coral comm~unit~c\ by part~culatc and ion~c metal f o r m that are captured by the overlying mucus of the organlc tlssue.

Zinc in the non-bleached specitnens of the northern Red Sea recorded rclattvcly high average concentration (2 1.3011 3.74 pglg) than thc blcachcd spccirncns In tllc same locality ( 1 1.0235 99 pglg) and In the beached

IZbbPONSE Of SCLLRAC l lhlAN CORALS 1'0 I HL NA ILIIIAL AND AN I IIROPOtiENIC IlhAVY MEI'AL STRFSSFF IN TIlF MORTlIERN RED SFA 4 N D CIIII.FS C)F Sl IF7 4ND AQARA

and non-bleached specimens in Sue7 and Aqaba gulfs (Table 1). Reichelt-Brushett and McOrist (1003) recorded that about one third of the increase in the zinc concentratton could be attributed to uptake by the 7ooxanthellae rather than to adsorption. Fallon el a/. (2002) attributed the high Zn contents in the corals to the anthropogcnic inputs, while Dar (2004) attributed the high Zn content in corals to tlie bioaccumulation tendency of the nletals in the carbonate phase of the underlying skeletons.

Iron in the different studied coral species rccordcd significant conccntratlons relative to the other metals. The non-bleach and the bleached specimens of the Gulf of Suez rccodcd thc highest avcragc concentrations 38.98k19.98 pglg (3.07 to 67.34 pgig) and 35.77+7-5.53 pg/g (9.97 to 95.55 pglg) than in northern Red Sea and Gulf of' Aqaba (Table 1). Iron has dctrital origin and accumulates over the mucus layer in a particulate form or might lntrodilcc to the coral skeleton in many phases as; carbonates, ovicles and liydroxitles.

Northcni Red Sea and sue^ Gulf recorded relatively high average concentrations of Pb In d ~ e non-bleachcd and bleached corals than Aqaba Ciulf. They were; 12.24, 17.64 pglg in the northern Red Sea, 16.67, 15.94pglg in Suez Ciulf and 10.09, 1 1.30 pglg m Aqaba Gulf respect~vely. Co recorded significant concentrations in the different locations. The highest avcragc \~alucs were recorded in the non-bleached and bleached specimens of Aqaba Gulf (5.29 and 6.46 pglg respectively). Cu rccordcd low concentrations in the diWcrent specimens and location with an average varied between 0.5 1 in the non- bleached specimens in the northern Red Sea and l.65pglg in the non-bleached specltnens in the Gulf of Aqaba. Tlic rccorded h~gh Pb, Co and Cu conccntrat~otis in the different locations are mainly attributed to the maritime activities, boat engines in fishing and tourist activities as well as the marine . paint remains. Reichelt and Jones (1994) showed that particle-bound hcavy metals can

be used to trace the distrib~~tion of re- suspended dredge spoils on coral reefs. They added, Zn and CU nere gcnerrilly canied in suspension by organic phases, and zinc and lead by iron oxides, with some transfer of lead to carbonates.

The recorded metal variations between the bleached and non-bleached species in the diffcrcnt localities show slight differences (Table I), which may indicatc that the different coral species can assimilate most of available inetal ions ant1 as particulate ibrms captured by thcir tissues or present in the surrounding uatcr column in thcir skeletal framework. The recorded average contents of the heavy elements in the non-bleached corals in the gulfs of Suer and Aqaba is highcr than the northern Red Sca that lnay dealing to the coral reefs in the gulfs are exposed to hazardous conditions much more than those in the northeni Red Sea (Fig. 5). Also, the recorded metal concentrations in the different locations are higher than thc recorded metals in the coral species by I>ar and Moha~ned (2005) in tlie northern Red Sea that may indicatc that the stresses on the coral communities arc increased with continuous developments in the coastal area and increasing the maritime activities near the fringing coral con~munities. The recorded data in the nun-bleached and bleached specimens show significant high and low variations relative to tlie other studied in the same localities and around the world as shown in Tables 2.3.

4. CONCLUSION

The studied hcavy ~netals in the non- bleach and bleached specinlens of the different coral forms in the northern Red Sea, Suez and Aqaba Gulfs reflect the anthropogcnic threats in each locality. The high Zn contents in tlie non-bleached corals and Pb in the bleached corals of the Northern Red Sea are attributed essentially to the tourist activities and the rclated industries as; coastal constructions, desalination plants,

automotit~e boats and shipyards, while the high Fe non-bleached and bleached coals in the Gulf of Sucz may indicate that the terrestrial infilling hi11 flash floods, dusty winds and/or coastal enhancements are the main sources of heavy metals in the gulf while the high Pb in the non-bleached corals in the same locality is due to oil terminals, industrial wastes, .fishing and maritime activities. The relatively high mctal contents in the coral species at Aqaba Gulf may be due to industrial activities, sewage spills and

military activities at Elat and Aqaba l iarbours.

Massive corals in the different localities recordcd the highest metal contents in the different localities relative to the other coral fortns that may dependant on the wide exposing surface area, the thick mucus layer and thc coral ability to assimilate the ionic metals fro111 the surrounding seawater. The obtained results arc indicating to thc coral species in the Aqaba Gulf and Gulf of Sue7 more stressf~tl than those in the northern Red Sea.

Aqaba Gulf (non-bleached corak) 45 Fe

40 Fe

Echinopora Lopophyllia Echinopora Porites Porites gemmacea corymbosa gemmacea Idea (D) lutea (31)

( € 4 (En)

Aqaba Gulf (Bleached corak) 45 Fe

Echinopora Lopophylia Echinopora hrites Pontes gemmacea corymbosa gemmacea lutea (D) lutea (Sh)

(En) (En)

Fig. (4): Heavy metal contents in the non-bleached and bleached corals at Aqaba Gulf.

IIESPONSE OF SCLt;Kt\CSINIAN CORALS 10 I IIb N12 I URAL ANL) AN I IIlIOPOtikNIC 1 ILAVY Mt SAL STRESSES IN TMENORTIlFIIN RFD SEKAND Qlll FS OF VIE7 AKD AQABA

Non-bleached corals

45

40 Fe

35

30

25

20

15

10

5

0 Red Sea Suez Guif Aqaba Gulf

Bleached corals

40

35

30

25

20

15

10

5

0 Red Sea Suez Gulf Aqaba Gulf

Fig. (5): Cgmparison of average heavy metals in the non-bleached and bleached coral reefs between tile northern Red Sea and tlie gulfs of Suez and Aqaba.

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