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GEO-03\INT-10  The geochemical and biological study of corals
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Predicting the future of scleractinian corals under the influence of expected climate changes (pCO2 and temperature)
Mohamed belasy ismail* , Department of zoology, Faculty of Science, Al Azher University, Egypt
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Climatechangese.g.oceanacidificationandwarmingcausedbyanthropogenicemissionofCO2arethegreatestglobalthreattocoralreefecosystems.ThechangeintheseawatercarbonatechemistryduetoOAisalarmingbecauseitspotentialaffectstheabilityoftropicalreef-buildingcoralsandothermarineorganismstoform(CaCO3)skeletons.DatashowthatadecreaseinpHfromcurrent(8.2units)toend-of-centuryprojectedlevels(7.7-7.8units)resultsina20-40%declineincoralcalcificationandanincreaseinthedissolutionrateofcarbonateskeleton,duetothesaturationstatusofCaCO3inseawaternegativelyaffectedbychangesinseasurfacetemperatureand/orCO2concentration.Reducedcoralgrowth,combinedwithweakercoralskeletonsandreefsubstrata,willincreasetheprobabilityofdamagetostructurallycomplexcoralsduringextremeweatherevents,leadingtoalossofreefstructurecomplexity,severelyreductionincoralsresilienceandrapiddeclinesinreefecosystembiodiversity.Therefore,thepotentialcapacityofscleractiniancoralsforacclimatizationoradaptationtooceanacidification(OA)anditsassociatedwarmingisakeyfactordeterminingtheirresiliencetofutureclimatechange.Reef-buildingcoralsareinhabitedbyfunctionallydiversemicroorganisms,whichplayvitalrolesinmaintainingholobionthealthandecosystemresilienceunderAnthropocene.Changesincoralmicrobiomecompositionisapotentialmechanismthatmayassistcoralstothriveunderstressfulconditions.Forinstance,thenorthernRedSeacoralsinhabitunderextremetemperaturesanomalies,withoutanybleachingsigns,suggestingthattheymayhaveselectiveandendemicmicrobiomesdonatethemthisuniquetolerability.SingleeffectofOAhadnosignificantinfluenceonbothSymbiodiniaceae&prokaryotic,whilethesynergisticeffectofOAandwarmingexacerbatethebleachingofcoralholobionts.Atthisstage,thereisnoclearconsensusaboutthephysiologicalandmoleculartraitsthatunderliecoraltolerancetoOAand/orwarming,consequently,reliableprojectionsoftheeffectsofclimatechangeonreefecosystemscannotbemade.Sothecurrentstudyaimstounderstandwhetherandhowcoralsacclimatizationoradapttolong-termofOAand/orwarming.WeassumethatthetolerabilityofcoralscorrelatedtoSymbiodiniummetabolismandthestabilityofitsassociatedmicrobiome |
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