art3A1010072Fs0026701505113

AMulti-moduleApproachtoCalculationofOyster(Crassostreavirginica)EnvironmentalBenefitsCarlF.Cerco1Received:30December2014/Accepted:15April2015/Publishedonline:30April2015SpringerScience+BusinessMediaNewYork(outsidetheUSA)2015AbstractEnvironmentalbenefitsareoneofthemotiva-tionsformanagementrestorationofdepletedbivalvepopulations.Wedescribeaseriesoflinkedmodulesforbenefitscalculation.Themodulesinclude:oyster(Cras-sostreavirginica)bioenergetics,materialstransportviathetidalprism,andbenefitsquantification.Quantifiedbenefitsincludecarbon,nitrogen,andphosphorusremovalandshellproduction.Themodulesaredemonstratedthroughappli-cationtotheGreatWicomicoRiver,atributaryofChesa-peakeBay,USA.Oystersonsevenreefs(totalarea2.89105m2)arecalculatedtoremove15.2,6.2,and0.2tonsperannumofcarbon,nitrogen,andphosphorus,re-spectively,fromtheGreatWicomico.Oystermortalitycontributes108tonsperannumdryweightshelltothereefs.KeywordsOysterbenefitsBivalvebioenergeticsEnvironmentalmodelsGreatWicomicoRiverChesapeakeBayIntroductionNearly30yearsago,aseminalpresentation(Newell1988)linkedculturaleutrophicationinanestuarytothedepletionofthenativebivalve,Crassostreavirginica(theEasternoyster).NewellproposedthatrestorationoftheoystertoChesapeakeBaycouldsignificantlyimprovewaterqualitybyremovinglargequantitiesofparticulatecarbon.Sincethenadditionalstudieshavedocumentedenvironmentaldegradationassociatedwithbivalvede-pletion(ZuErmgassenetal.2013)andexaminedthepotentialforenvironmentalimprovementthroughbivalverestoration(CercoandNoel2007;Coenetal.2007;GrabowskiandPeterson2007;Brickeretal.2014).Thepotentialforachievementofenvironmentalbenefitsthroughbivalverestorationhasspecialsignificancetomanagementinviewofthedifficulty,expense,andtechnologicalchallengesassociatedwithcontrolsonex-ternalpollutionsources.Anyplanforbivalverestorationrequiresquantificationofassociatedbenefits.Thequantificationcanrangethroughavarietyofspatialscales,fromlocal(Nelsonetal.2004;Kelloggetal.2013)tosystem-wide(CercoandNoel2007),andlevelsofcomplexityrangingfromextrapolation(Higginsetal.2011)tocomplexenvironmentalmodels(NewellandKoch2004;Smithetal.2009).Weproposethatbenefitscalculationrequires:(1)representationofor-ganismsandtheirinteractionwiththeirsurroundings;(2)representationoftheenvironmentsurroundingtheorgan-isms;and(3)definitionandcalculationofbenefits.Wedemonstrateherehowmodulesofvaryingcomplexitycanbecombinedtoquantifytheenvironmentalbenefitsofoysterrestoration.ThreemodulesaredocumentedanddemonstratedthroughapplicationtotheGreatWicomicoRiver,Virginia,USA.ElectronicsupplementarymaterialTheonlineversionofthisarticle(doi:10.1007/s00267-015-0511-3)containssupplementarymaterial,whichisavailabletoauthorizedusers.&[e-mail]1EnvironmentalLaboratory,USArmyEngineerResearchandDevelopmentCenter,3909HallsFerryRoad,Vicksburg,MS39180,USA123EnvironmentalManagement(2015)56:467–479DOI10.1007/s00267-015-0511-3MaterialsandMethodsModule1:OrganismsandTheirInteractionswiththeEnvironmentBivalvesarerepresentedinamodulewhichconsiderstwopropertiesofapopulation:numberofindividualsandin-dividualsize.Individualsareorganizedin‘‘schools,’’atermadoptedfromamodelofAtlanticmenhaden(DalyanderandCerco2010)afterwhichthismoduleispatterned.Thenumberofindividualsinaschoolisinitiatedthroughtherecruitmentprocess.Subsequently,thenumberofindividualscanonlydeclineduetothemortalityfromfourprocesses:DN¼DNstvþDNsufþDNnatþDNfsh;ð1ÞwhereDNisthenumberofindividualslostduringamodeltimestep,andDNstv,DNsuf,DNnat,andDNfsharethenumberofindividualslosttostarvation,suffocation,nat-uralmortality,andfisheries,respectively.DetailsofthemortalitytermsareprovidedinOnlineResource1.Allindividualsinaschoolareconsideredtobeidentical.Theirsizeandstatusisdeterminedbyabioenergeticsmodelwhichconsidersenergy(joules)asitscurrency.ThebioenergeticsrelationshipisdWdt¼CBMþSþFþU½fg1Eprd;ð2ÞwhereWistheindividualdryweight(g),Cisthecon-sumption(js-1),BMisthebasalmetabolism(js-1),Sisthespecificdynamicaction(oractiverespiration,js-1),Fisthefeces(js-1),Uistheexcretion(js-1),andEprdistheoysterenergydensity(jg-1DW).Eprdconvertsbetweenenergygainedorlostandindi-vidualweight.Theconversionisrequiredsincemostconventionalenvironmentalmodelsandobservationsaremassbased.Thetotalweightofanindividualconsistsofshell,softtissue,andreproductivematerial.Here,weconsideronlyorganicmatterassociatedwiththesethreecomponents,quantifiedasdryweight.Whenthenetchangeinenergyispositive(consumptionexceedslosses),energyisroutedtoeachcomponentviafixed,user-specifiedfractions.Whenthenetchangeinenergyisnegative(lossesexceedconsumption)thelossisextractedsolelyfromthesofttissuefraction.Consumptionistheproductoffiltrationrateandenergydensityofpreyinthesurroundingwater.Intheevent,thequantityfilteredexceedsthemax-imumingestionrateoftheorganism,theexcessisrejectedaspseudofecespriortoconsumption.Filtrationrateandbasalmetabolismarecalculatedbyallometricrelationships(OnlineResource1)parameterizedtoyieldratesprevi-ouslydeterminedforEasternoysters(CercoandNoel2007).Activerespiration,feces,an