LISTOFFIGURES
Figure1.Studysitesselectedtocollectjuvenile H.flavolineatum and L.apodus inSt.Croix. 3
Figure2.Studysitesselectedtocollectjuvenile H.flavolineatum and L.apodus inPuertoRico. MG=mangrovearea,SG=seagrassarea. 4
Figure3.PictureoftheLAICPMSusedtoanalyzetraceelementalconcentrationsatthe GraduateSchoolofOceanographyURIICP-MSlaboratory. .................................................6
Figure4.CanonicalScoresPlotsfor H.flavolineatum,St.Croix(top)andPuertoRico(bottom) forsamplingyears2006and2007.
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Figure5.CanonicalScoresPlotsfor L.apodus,St.Croix(top)andPuertoRico(bottom)for samplingyears2006and2007 32
Figure6.Spatialandtemporalvariabilityintraceelements andstableisotopesmeasuredin otolithsofYOY H.flavolineatum collectedinSt.Croix(USVI)in2006and2007. Alltraceelementdata[Element/Cax103]areLn(X+1)transformed..................................33
Figure 7.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY H.flavolineatum collectedinPuertoRicoin2006and2007.Alltrace elementdata[Element/Cax103]areLn(X+1)transformed. 34
Figure8.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY L.apodus collectedinSt.Croix(USVI)in2006and2007.Alltrace elementdata[Element/Cax103]are Ln(X+1)transformed.................................................35
Figure9.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY L.apodus collectedinPuertoRicoin2006and2007.Alltrace elementdata[Element/Cax103]areLn(X+1)transformed.
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INTRODUCTION
Manycoastalfishspecieshavejuvenileandadultlifestagesthatoccupyspatiallyseparatedhabitats.The juvenilesoftenrecruittonearshore habitatswheretheyresideformonthstoyearsbeforemigratingto offshorehabitatstojointheadultpopulation.Inaddition,juvenilesofmanyspecieswiththislifehistory patternrecruittomorethanonetypeofnearshorehabitat,forexample,mangroveandseagrassmeadows, andthosedifferenthabitatsarelikelytovaryinquality.Thehighestqualityjuvenilehabitatsareoften referredtoas‘nursery’habitats.Determiningwhichjuvenilehabitatsarefunctioningasnurseryhabitats isimportanttobothunderstandingtheecologicalrolesofthedifferentjuvenilehabitatsandmanaging harvestedfishpopulationsandcoastalresources.Identificationofnurseryhabitatsisparticularly importantwhensomeofthenearshorehabitatsusedbyjuvenilefisharevulnerabletodegradationorloss. Otolithmicrochemistryprovidesapowerfulmeanstoidentifyspawningsitesandtotrackdispersaland retentionoffishthroughoutontogeny.Elementalfingerprintsinotolithscanbeusedtoreconstructlife historychronologiesoffishandcanbeappliedtopotentiallydeterminethesiteofnataloriginandif adultsexhibitfidelitytosuchsites,returningtothesitesoftheirnataloriginforspawning. Chemical habitattagsintheotolithsofjuvenilefish havebeenusedtodifferentiateindividualsfromdifferent estuarine/riverinesystems(Thorroldetal.1998a,Thorroldetal.1998b,GillandersandKingsford2000, Gillanders2002b)andalternativetypesofnearshorehabitats,includingestuaryversusrockyreef (GillandersandKingsford1996)andestuaryversussubtidalsandflats(Yamashitaetal.2000,Forrester andSwearer2002).Inaddition,throughchemicalanalysisofthejuvenilecoreofadultotoliths,the habitattaghasbeenusedtodeterminethe proportionoftheadultpopulationthatresidedindifferent juvenilehabitats(Yamashitaetal.2000,Thorroldetal.2001,Gillanders2002a)
TheFrenchgrunt Haemulonflavolineatum andtheschoolmaster Lutjanusapodus areeconomically importantspecies thatoccurintheWesternAtlantic,rangingfromBermudatoBrazil,includingthe CaribbeanSea.Theyoccurinlargeschoolsonrockyandcoralreefsto60mdepth.Juveniles(<2cm) settlefromtheplanktonafter20-30daysinahighlyaggregatedpattern(BrothersandMcfarland1983, Mcfarlandetal.1985,Shulman1985,Lindeman1997)withthemajorityoffish(95%)settlingonto seagrassandmangrovehabitatsandabout5%settlingontostructuressuchasrubbleorcoralheads (ShulmanandOgden1987,RookerandDennis1991,Nagelkerken2000).Afterafewweekstomonths thesmalljuvenilesmigratetojoinschoolsofintermediate-sizedindividualspresentinmangrovehabitats (Boulon1992;RookerandDennis1991;Nagelkerken2000a,b,c,Appeldoornetal.1997)orbackreef structures,usuallypatchreefs(OgdenandEhrlich1977,BrothersandMcFarland1981,Helfmanetal. 1982,McFarlandandHillis1982,MateoandTobias2001a,bAdamsandEbersole2002,Mateoand Tobias2004).Largejuvenileseventually emigratefromtheseschools,andarepresumedtomovetoforereefhabitats,wheretheyresideindividuallyorinsmallgroups(Appeldoornetal.1997;Nagelkerkenet al.2002).Adultsofmostspeciestypicallyformschoolsofafewtoseveralhundredfishesoncoralreefs bydayandfeedinadjacentseagrassandmangroveareasbynight(Appeldoornetal.1997,Nagelkerken etal.2002).
Thisprojectaimstoinvestigatetheutilityofnaturallyoccurringhabitattagstodeterminehabitatlinkages intropical nearshoreecosystemsbyjuvenileandadultfishpopulations.Thisisaninitialcrucialstepto quantifytherelativecontributionandconnectivityofnearshorehabitatsforadultfishpopulations.
Thespecificquestionsthatthisstudyattemptstoaddressare:
Cantropicalfishsettlementandnurseryareasbeidentifiedbychemicalsignaturesfromotolith microchemistry?
Arespatialdifferencesinthechemicalsignaturesfromtropicaljuvenilefishwithinnurseryareas consistenttemporally?
METHODOLOGY
Studysites
StCroix
SampleswerecollectedfromfiveareasintheIslandofStCroixUSVIfromfiveareas:AltonaLagoon, GreatPondBay,TeagueBay,SaltRiverandTurnerHole(Figure1).TurnerHoleandGreatPondand TeagueBaywereselectedasnon-mangroveenvironmentswhereasAltonaLagoonandSaltRiverwere selectedasmangroveenvironments.
TeagueBay,TurnerHoleandGreatPondarepartoftheStCroixEastEndMarinePark.Thisisthefirst territorialparkintheU.S.VirginIslands(TNC2002)andcontainsthelargestislandbarrierreefsystemin theCaribbean. TeagueBayis parttheTeagueBaybank-barrierreefsystem thatextendsfromPullPoint toLambPointonthenortheastcoastofSt.Croix(Figure1). Thereisalargeback-reeflagoonwiththe distancefromtheshoretothereefvaryingfrom500mto700m(Mateo&Tobias2001)andthedepth rangingfrom8mwestofTeaguePointto1minthebackreefatbotheasternandwesternendsofthe lagoon(Burkeetal.1989).Thezonationpatterninthisembaymentischaracteristicforatypicalreef (Burkeetal.1989)withseagrassandsediment-dwellingorganismsdominatinginthelagoon. The abrupttransitionfromthelagoontothebackreefismarkedbyscatteredcoralcolonies(Montastrea annularis and Porites spp.),severalspeciesofgorgonians,andfleshyalgae.
TurnerHolebayispartofthesoutheasternendbank-barrierreefsystemthatextendsfromEastPointto VagthusPoint(Hubbard1989).Thisembaymentisalmost1000mlongandapproximately300mwide. Depthinthelagoonrangesfromamaximumofapproximately8to1matbotheasternandwesternends andmostofthebottomiscoveredbyseagrasses(e.g., Thalassiatestudinum and Syringodiumfiliforme)in bedsofvaryingdensity.
GreatPondbehindGreatPondBay(Figure1)isthesecondlargestsaltpondintheVI(Tobias2001).The bank-barrierreefoffshoreaffordsprotectedbackreefwatersforextensiveturtlegrassmeadows.Itis approximately2kmlongandboundedonitslandwardsidebythebaymouthbarandseawardbya continuouscoral-algalreef(Bruceetal.1989).Theinshoreportionofthelagooniscoveredbythe seagrass, Thalassiatestudinum (turtlegrass)andlesseramountsof Syringodiumfiliforme (turtlegrass). Scatteredcoralheads,including Montastreaannularis, Diploriastrigosa, and Siderastrea spp., alsooccur inthelagoon.Lagoondepthsrangefrom1-7m.
TheSaltRiverestuaryisamangrove-fringedlagoononthenorthshoreofStCroixseparatedfrom the openoceanbyafringingreef(AdamsandTobias1999).Theshallow(4m)estuaryiscomposedofan outerbayandtwoparallelinnerbays(TritonBayandSugarBay)andcontainsasmallmarina.The majorityofmangrovehabitatisalongtheshorelinesof theinnerbays,withonlylimitedgrowthonthe westernshoreoftheouterembayment.Duetotheimportantnaturalvaluethatthisecosystemhas,the USVIDepartmentofPlanningandNaturalResourceshasidentifiedSaltRiverasanareaofparticular concern(APC)andanareaforpreparationandrestoration(APR).
AltonaLagoonisanenclosedmangrovelagoononthenortheastcoastofStCroix.Formerlyanopen estuary,thegradualdepositionofcalciumcarbonatesandsofbiogenicoriginovergeologictimehave formedabaymouthbartothenorth,connectingrockyheadlandsandseparatingthelagoonfromthe CaribbeanSea(Tobias1996).ThelagoonisconnectedtotheChristiansted Harborbackreefareabya singlenarrowchannel<10mwide.Sandbuildupinthethreeculvertsfurtherrestrictswaterexchangein AltonaLagoon.Maximumwaterdepthofthelagoonis3to5meters.Redmangrovescovertheentire shorelineofthelagoon.(Tobiasetal.1996).
Figure1.Studysitesselectedtocollectjuvenile H.flavolineatum and L.apodus inSt.Croix. MG=mangrovearea,SG=seagrassarea.
PuertoRico
SampleswerecollectedintwostudysitesontheIslandofPuertoRico:LaPargueraandGuayanillaBay (Figure2).Eachareacontainsbothmangroveandnon-mangrovehabitattypeswherejuvenileFrench GruntsandSchoolmasterarefound.
TheshelfofLaPargueraextends8-10kmoffshore;awell-developedcoralreefformationexistsatthe borderoftheshelfandservesasafirstbarrieragainstwaveaction.Twootherlinesofbarrierreefs providefurtherprotectionforthemangrovecoastlineandsubmergedseagrassbedsofLaParguera.La Pargueraisrecognizedfortheexceptionalvalueofitsmarineresources,whichincludetwo bioluminiscentbays(BahíaFosforescenteandMonsioJosé),acoastalmangrovefringewithseveralsmall lagoons,mangroveislandsassociatedwithcoralreefs,seagrassbeds,andperhapsthebestdeveloped, mostextensivecoralreefecosystemoftheisland.Asaresult,bothlocalandtransienttouristpopulations haveincreaseddramaticallyinrecentyearsimpactingthelocalenvironmentheavily.Tocontrolthis,the PuertoRicoPlanningBoardclassifiedLaPargueraasaZoneofSpecialPlanning.Infurtherrecognition oftheecologicalvalueofitsmarineresources,LaParguerahasalsobeendesignedasaNaturalReserve bytheDepartmentofNaturalResources.
GuayanillaBayisasemi-enclosedbaylocatedinthesouthcoastofPuertoRicoandcontainsboth mangroveandnon-mangrovejuvenilefishhabitats.Theshallowwatersarerichincoralreefsandcontain extensiveareasofseagrassthatprovideanaturalnurseryhabitatforvariousjuvenilefishspecieswith commercialvalueforlocalfishermen. (Castro &Garcia1996;Vicente&Associates2003). Industrial developmentonGuayanillaBaywasbasedonthecreationofahugepetrochemicalandoilrefining complexandsubsidiaryindustriestosustainlarge-scaleindustrialproductioninnearbyareas(Lopez 1979).
St.Croix
TeagueBay(SG)
Altona Lagoon(MG)
TurnerHole(SG)
GreatPond(MG)
SaltRiver(MG)
Figure2.Studysitesselectedtocollectjuvenile H.flavolineatum and L.apodus inPuertoRico.MG =mangrovearea,SG=seagrassarea.
Samplingofjuvenilefish
StCroix
FromMay9toMay192006andfromMay5 toMay252007,young-of-the-year(YOY)andsmall juvenilefishwerecollectedaroundmangroveareasandnon-mangroveareasinStCroixwithabeach seineandfishtraps.Thebeachseinenetusedforthisstudymeasured30.5mx122cm.Thenetmesh sizewas1.3cmstretchmesh.Fishtrapsusedinthisstudywererectangular(92cmx57cmx19cm)and madefromvinyl-coatedwirewith1.3cm2 barmesh.Thenumberoftrapsusedinthisstudywas10. Eachtrapwasbaitedwithapproximately0.5lbherring andhadasoaktimeof2days.Twentyto25 individualsofschoolmasterandfrenchgruntbetween3cmto12cmtotallengthwerecaughtin mangrovestations:(SaltRiver,Altonalagoon),andnon-mangrovestations(TeagueBay,TurnerHole, GreatPond)(Figure1).DistancesamongstationsinthenorthcoastofStCroixwereabout8to16km whereasinthesouthcoastdistancewas5km.Sampledfishwerekeptfrozenuntildissectiontoobtainthe otoliths.
PuertoRico
FromJune15toJune242006andSeptember152006,andfromJune12toJune222007,Young-of-theyear(YOY)andsmalljuvenilefishwerecollectedaroundmangroveareasandnon-mangroveareasin PuertoRicowithbeachseineandfishtraps.Thesamplingeffortwasdoneincollaborationbystafffrom UniversityofPuertoRico’sDepartmentofMarineSciences(Dr.RichardAppeldoorn).Twentyto25 individualsofschoolmasterandfrenchgruntbetween3cmto12cmtotallengthwerecaughtin mangrovestations(BahiaMontalva,MariaLanga,PuntaGuayanilla)andnon-mangrovestations(Corral, ElPalo)(Figure1).DistancesamongstationswithinLaParguerawereabout3to5km.Distancesamong
Pta.Guayanilla(MG)
MariaLanga(MG)
PuertoRico
Corral(SG)
ElPalo(SG)
Montalva (MG)
thetwobays(GuayanillaBay,LaParguera)was28km.Sampledfishwerekeptfrozenuntildissectionto obtaintheotoliths.
Samplingofadultfish
Twentytotwenty-fourfirstyear-oldsubadultsof L.apodus and H.flavolineatum werecollectedfrom reefsadjacenttoSaltRivermangrovelagooninStCroixwithspearfishingduringMay29toJune3, 2007.InPuertoRicofishwerecollectedfromtheLaPargueraareaaroundtheoffshoreTurrumotereef whichisadjacenttoBahiaMontalva(Mangrovestation)andCorral(seagrassstation),betweenJune22to June27,2007.Fishbetween15-20cmfork(FL)lengthfor L. apodus and12-15cmFLfor H. flavolineatum werekeptforanalysis.Thesesizerangesapproximate1year-oldfish(FishBase). Fish werekeptiniceorfrozenuntildissectiontoremovetheotoliths.
Otolithmicrochemistry
Preparationofjuvenileandadultotolithsfortracemetalandisotopeanalysis
Standardlength,forklength,andwetweightweremeasuredforeachfishpriortodissectiontoremove theotoliths.Bothleft(tracemetals)andright(stableisotopes)sagittalotolithswereremoved,cleanedof endolymphatictissue,rinsed3xwithMilli-Qwater,andallowedtodryinaClass100laminarflowhood. Sampleswereplacedinacidwashed2.5mlsnapcapcontainers.Eachotolithwasthenmeasuredand weighed(±0.01mg)onaThermoCahnmicrobalance.Atotalof384otolithswerepreparedfortrace metalandstableisotopesanalyses(FrenchgruntN=192,schoolmasterN=192)foryear2006.In2007a totalof372otolithswerepreparedfortracemetalandstableanalyses(FrenchgruntN=192,schoolmaster N=180).Foradultscollectedin2007,atotalof93otolithswerepreparedfortracemetalanalyses (FrenchgruntN=48,schoolmasterN=45).
TraceMetalAnalysis
OtolithsfortracemetalanalysiswereembeddedinThreeSystemEpoxyusingflatembeddingsilicon rubbermolds(Pelco#105)andleftfortwodayswhiletheepoxyhardened.Traversethinsectionsof400 µmweremadewithaBuehlerlowspeedsaw.Thesesectionsweremountedonamicroscope petrographicslidewiththermoplasticglueandgroundtothecoreinthesagittalplanewithlappingfilm (30,15,9and3microns).Surfacecontaminationwasremovedbyultrasonicallycleaningthesectioned otolithsinultrapurewaterfor5minutesandlefttodryfor24hoursinalaminarflowhood.Slideswere storedinpetrographicslideboxesuntilchemicalanalysis.
Traceelementalconcentrationswereanalyzedwithlaserablation-inductivelycoupledplasmamass spectrometry(LA-ICPMS)(ThermoX-SeriesIIQuadrupoleICP-MScoupledwithaUPS213Nd:Yag, NewWaveTechnologiesLaser)(Figure3).Priortomicrochemicalanalysis,otolithincrementnumber andwidthwasanalyzed(Image-Proimageanalysissoftware)sothatwecouldsampletracemetalsinthe appropriateregionsoftheotolith(larval,immediatepost-settlement,juvenile,recentgrowth).Forthe YOYandadultreeffish,classificationanalysisdatafromthepostsettlementperiodwasused.Before analysis,theareawaspreablatedtoreducesurfacecontamination.Threereplicatespotsinthe postsettlementzoneofeachotolithwerequantifiedataspotsizeof40µmwiththelaseroperatingat5 Hz,andascanrateof30seconds(Table1).Initiallyweexamined15elementsinjuvenilefrenchgrunt otoliths(Li,Rb,Co,Na,Mg,Al,S,Ca,Mn, Mg,Se,Sr,Ba,Pb,U).Nineelementswereconsistently detectibleabovebackgroundlevelsinjuvenileotoliths(Na,Sr,Ba,Mg,Mn,Ba,Cu,Co,Rb).All elementconcentrationswerestandardizedwithNIST612glassstandards(NationalInstituteofStandards andTechnology- U.S.DepartmentofCommerce).Thestabilityoflaserconditionswasevaluatedby examiningtherelativestandarddeviation(RSD)oftargetelementsintheNIST612glassstandards.
Stableisotopeanalysis:
Forinorganic 13Cand 18OstableisotopesanalysisofYOYfishtherightsagittalotolithsweregroundto powderandthepowderplacedinacidwashed2.5mlsnapcapcontainers.Forfirstyearsubadults,thethin
sectionsofeachotolithwereattachedtoamicroscopeslideandacomputer-drivenmicromillingmachine (WHOI,McleanLaboratory)wasusedtofreethejuvenilecorefromthesurroundingotolith.Thiscore materialwasthengoundandplacedinacidwashed2.5mlsnapcapcontainers.Stableisotopesofthese otolithsampleswere determinedatthelaboratoryofDr.PeterSwartatRSMAS,UniversityofMiami, usingisotoperatioanalysiswithanautomatedcarbonatedevice(commonacidbathat90°C)attachedtoa Finnigan- MAT251gasratiomassspectrometer.DatawereexpressedrelativetoPDB(Peedee Belemnite).Externalprecision(calculatedfromreplicateanalysesofaninternallaboratorycalcite standard)was0.02%for 13Cand0.03%for 18O.
Figure 3.PictureoftheLAICPMSusedtoanalyzetraceelementalconcentrationsattheGraduate SchoolofOceanographyURIICP-MSlaboratory.
StatisticalAnalysis
UnivariateandmultivariatemethodswereusedtodetermineifYOYotolithchemistryinthe postsettlementregionvariedamongsitesandbetweenyears.Todetectdifferencesintheconcentrations ofparticularelementsandmultielementfingerprintsamongsitesandbetweenyearsanalysesofvariance (ANOVA)andmultivariateanalysesofvariance(MANOVA)wereperformed.Pillai’stracewaschosen asthe teststatisticbecauseitismorerobusttosmallsamplesizes,unequalcellsizes,andsituationsin whichcovariancesarenothomogeneous.Tukey’sHSDtestwasusedtodetectaposterioridifferences amongmeans(α=0.05).Beforestatisticaltesting, residualswereexaminedfornormalityand homogeneityamongstations.Tomeetmodelassumptions,allanalyseswereperformedonnaturallog transformeddata.Canonicaldiscriminantfunctionanalyses(DFAs)onfrenchgruntandschoolmaster postsettlement datawereusedtovisualizespatialdifferenceswithinsitesandyearsandtoexamine classificationsuccessforjuvenilesfromdifferentsitesorhabitatsacrossyears.Crossvalidationswere performedbyusingjackknife(‘‘leaveoneout’’)proceduresin Systat.
Two-wayANOVAwasusedtotestifthereweredifferencesinsizeamongstationsandyearsforboth species.Wealsoexaminedrelationshipsbetweenotolithweightandotolithelementalcompositionand isotopicsignatureswithanalysisofcovariance(ANCOVA).Iftherewassignificantrelationship,we removedtheeffectofsize(otolithweightusedasaproxyforfishsize)toinsurethatdifferencesinfish sizeamongsamplesdidnotconfoundanysite-specificdifferencesinotolithchemistry.Concentrationsof elementwereweight-detrendedbysubtractionofthecommonwithin-grouplinearslopefromthe observedconcentration(concentration – bi(otolithweight))(Campanaetal.2000)
Amaximumlikelihoodbasedanalysiswasusedtodetermine(1)theabilityofelementalfingerprintsto recordcorrectlytheproportionofrecruitsfromdifferenthabitats,and(2)theproportionofadultfish originatingfromthedifferentnurseryhabitats.Forthislatteranalysis,weusedtheelemental concentrations andisotopicsignaturesofpostsettlementregionsofjuvenileandadultschoolmasterand FrenchgruntsfromspecificlocationsfromPuertoRicoandStCroix.ForPuertoRico,juvenileswere collectedfromCorral(seagrass)andMontalva(mangrove),andthesubadultswerecollectedfrom Turrumote,whileinStCroixbothjuvenilesandsubadultswerecollectedfromSaltRiver.
Themaximumlikelihoodestimatorwaschosenbecauseitperformsbetterthanclassification-based estimatorsandprovidesmaximumdiscriminatorypowerinmixedstocksituations(Millar1987,1990). Forexample,forclassifyingnewcases(e.g.adultsbasedonjuvenileelementalsignatures)discriminant analysisassumesequalprobabilitiesofclassificationtoeachjuvenilegroup.Although priorprobabilities canbechangedinmanystatisticalpackages,thepriorprobabilitiesarerarelyknowninnature.Sinceprior probabilitiesmaydeviategreatlyfrombeingequal,discriminantanalysisisgenerallynotrecommended. Maximumlikelihoodanalysisestimatestheproportionofeachreferencepopulation(e.g.mangrove)in theunknown(e.g.offshorereefs)mixtureandthusindividualfisharenotassignedtoaparticularsource (Campana1999,Gillanders2005).
RESULTS
SizeDistribution
MeanFL ofjuvenileFrenchgruntcollectedateachstationvariedbetween3.8and9.4cmwhilefor schoolmastermeanFLvariedbetween4.5and11.3cm(Table2).Thereweresignificantdifferencesin meanlengthamongstations(ANOVAp<0.001)andbetweenyears(ANOVAp<0.05)foreachspeciesin eachisland.
Multi-elelementalConcentrations
ResultsofMANOVAshowedthatmulti-elementalsignaturesofbothjuvenileFrenchgruntand schoolmasterdifferedsignificantlyamongstations(MANOVAp<0.001)andyear(MANOVA p<0.001) forStCroixandPuertoRico(Table3,Figure4,5).Therewasalsosignificantinteractionamongstation, andyear(MANOVAp<0.001)implyingthatthemultitagsignaturesdifferedamongyearsdependingon thestationstudied. Signaturesalsodifferedsignificantlyamonghabitats(MANOVAp<0.001)andyear (MANOVAp<0.001)(Table5).
ClassificationsuccessforFrenchgruntnurserysiteswithinSt.Croixforthetwoyearsrangedfrom87to 92%andinPuertoRicofrom80to84%(Table4,Figure4). Whenstationswerecombinedamong habitats,classificationsuccessbetweenmangroveandseagrasshabitatsvariedbetween95to96%inSt. Croixand84to91%inPuertoRico(Table4).
ForschoolmasterclassificationsuccesswithinthefourSt.Croixnurseriesvariedbetween76to77%and between84to87%inPuertoRico(Table6,Figure5).Whendatafromthemangrovehabitatsand seagrassnurserygroundswerecombinedtheresultsofthecrossvalidationprocedureshowthatthe classificationaccuracyof theotolithsfromthetwohabitatsvariedbetween86to89%inStCroixand from94to99%inPuertoRicoforallyears(Table6).
IndividualElementalConcentrations
FrenchGrunt:InSt.Croix,someofthetraceelementandstableisotopesexaminedshowedasignificant relationshipwiththecovariableotolithweightintheANCOVA,requiringtheeffectoftheotolithweight toberemovedforsubsequentANOVAanalysis(Table7).ForPuertoRico,therewerenosignificant relationshipsamongelementalconcentrationsandstableisotopeswiththecovariableotolithweightinthe ANCOVA(Table7).
TheindividualelementalconcentrationsandisotopicsignaturesofFrenchgruntsvariedsignificantly amongstations(ANOVAp<0.001)andyears(ANOVAp<0.001)forSt.CroixandPuertoRico(Table7). Therewasalsosignificantinteractionamongsitesandyear(ANOVAp<0.001)forbothIslands(Table7).
InStCroixthereweresignificantvariationsofSr,Ba,Na,Co, 13 Cand 18 Oamongsitesduringboth2006 and2007(ANOVAp<0.001,Tukeytestp<0.05),,whileCushowedsignificantvariationamongsitesonly in2006andMgin2007(ANOVAp<0.001,Tukeytestp<0.05),(Figure6).AllelementsbutCu,andboth stableisotopes,alsoshowedsignificantwithinstationvariabilitybetweenyears(Table7).ForPuerto Rico,elementalconcentrationsofNa,Sr,Ba,MgCo, 13Cand 18Ovariedsignificantlyamongsitesin2006 whereasin2007onlySr,Ba,Cu, 13Cand 18Ovariedamongsites(ANOVAp<0.001,Tukeytestp<0.05), (Figure7).TherewassignificantwithinstationvariabilitybetweenyearsforNa,Mg,Cobutnoneforthe othermetalsorforeitherstableisotope.Therewasnoapparenttrendinelementconcentrationsamong stationsforbothIslands(Figure6,7).Someelementsthatwerehigheratagivenstationinoneyearwere lowerduringthenextyearwhileinothecasesthereverseistrue(Figures6,7).Whenstationswere combinedbyhabitatSrand 13CweresignificantlyhigherinseagrasshabitatsinSt.CroixwhereasNa, Mg,Coand 18Owerehigherinmangrove(Table8).InPuertoRicoSr, 13Cand 18Oconcentrationswere significantlyhigherinseagrasswhileCo,Cuweresignificantlyhigherinmangrove.OnlyNaand 18O
variedacrossyearswhenstationswerecombinedbyhabitatforSt.Croix,whileforPuertoRicoonlyMg, Covaried.
Schoolmaster:InSt.Croix,onlyonetraceelementexamined(Ba)showedasignificantrelationshipwith thecovariableotolithweightintheANCOVA,requiringtheeffectofthecovariabletoberemovedfor bothIslands(Table9).
InStCroixandPuertoRico,theelementalconcentrationsandisotopicsignaturesofschoolmastervaried significantlyamongstations(ANOVAp<0.001)andyears(ANOVAp<0.001)(Table9).Therewasalso significantinteractionamongsitesandyear(ANOVAp<0.001).
ThereweresignificantvariationsamongsitesofNa,Sr,Ba,Mg,Co,and 13Cduring2006inSt.Croixand Ba,Co, 13Cand 18OinPuertoRico(ANOVAp<0.001,Tukeytestp<0.05),(Figure8,Figure9, respectively).During2007Na,Sr,Cu,Co, 13Cand 18OvariedamongsitesinSt.Croix(Figure8)andSr, Ba,Mg,Cu, 13Cand 18OforPuertoRicoin2007(ANOVAp<0.001,Tukeytestp<0.05),(Figure8, Figure9,respectively).TherewaswithinstationvariabilitybetweenyearsforNa,and 18OforSt.Croix, andSr,Ba,CoforPuertoRico(Table9).Therewerenoapparenttrendsinelementconcentrationsamong stationsforSt.Croix.Therewerenotemporalvariationsinisotopicsignatureswithinstations forPuerto Rico.Someelementsthatwerehigheratagivenstationwereloweronthenextyearandviceversa.When stationswerecombinedbyhabitatonlyNaand 18OelementalconcentrationsvariedacrossyearsforSt. Croix,andonlyBa,CoforPuertoRico.InSt.CroixSr,Cu,and 13Cweresignificantlyhigherinseagrass habitatswhereas 18Owashigherinmangrovehabitats.Therewerealsohigherbutnotstatistically differentconcentrationsBainseagrasshabitatsinStCroixandofMginmangrovehabitats.InPuerto RicoSr,Baand 13CweresignificantlyhigherinseagrasshabitatswhileMgand 18Oconcentrationswere higherinmangrovehabitats(Table10).
SubAdultConnectivity
Theresultsfromthemaximumlikelihoodanalysisshowedthatusingtracemetalandstableisotopedata forjuvenileschoolmastercollectedin2006,almost100%ofthesubadultscollectedin2007camefrom mangrovenurseryhabitatsinbothIslands(Table11).
ForFrenchgruntstheadultsoriginatedfrombothhabitatswith70%comingfrommangroveand30% fromseagrassinPuertoRicoand40%frommangroveand60%fromseagrasshabitatsinStCroix.
DISCUSSION
Theuseofachemicaltagtodiscriminatefishresidingindifferenthabitatsrequiresthattheotolithsoffish collectedfromthosehabitatsdifferintheirchemicalcomposition.Inordertousethistagtoidentifyadult fishthatonceresidedinthedifferentjuvenilehabitatsotolithsshouldbecharacterizedusingindividuals collectedfromallpossiblesourcehabitatsfortheadultpopulationunderstudy(Campanaetal.2000). OurresultsindicatethatotolithsofjuvenileschoolmasterandFrenchgruntsmeetthesecriteria.They differsignificantlyintheirchemicalcompositionbetweenmangroveandseagrasshabitatsandthe chemicalhabitattags(mangroveandseagrass)werepresentanddistinguishableinjuvenilescollected overlargeandsmallgeographicareas(5to28km).Thismakesitpossibletousethesemicrochemical tagsintheirotolithstodiscriminatebetweenfishcollectedfromdifferenthabitats:mangoveandseagrass. Byanalyzingthejuvenileportionofotolithsofadultfishwecanusethesediscriminatoryfunctionsto determinethehabitattypeinwhichtheadultfishspenttheirjuvenileperiod.Preliminaryresultsindicate thatnearlyalladultschoolmastercollectedspentthejuvenileperiodoftheirlivesinmangrovehabitats whileadultFrenchgruntswereapproximatelyequallydistributedbetweenbothhabitatsasjuveniles.
TheelementalcompositionofjuvenileschoolmasterandFrenchgruntotolithsvariedconsiderablyamong stationswithinislandsandbetweenyears.WefoundverystrongdifferencesintheconcentrationsofSr, Ba,Mg,NaandCoaswellasintheisotopicsignaturesof 13Cand 18Oamongstationswithinislands. Mostoftheseelementalfingerprintswithinstationsalsovariedsignificantlyacrossyears.Giventhese interannualdifferences,age-0schoolmasterandFrenchgruntelementalsignaturesmustbeanalyzedona year-class-specificbasis.Havingasuiteofyear-class-specificandregion-specificotolithelemental signaturesavailableshouldproveespeciallypowerfulascohort-specificandtime-specificapproachescan beappliedtoestimatemovementdynamicsandconnectivity
Wealsofoundsignificantdifferenceswhentracemetalandstableisotopeconcentrationswereanalyzed byhabitat.WithschoolmasterSr,Baand 13CweresignificantlyhigherinseagrassstationswhereasMg and 18Owerehigherinmangrovestations.ForFrenchgrunt,Srand 13Cwerealsohigherinseagrass. Therewerenocleardistinctiononwhatelementalsignatureswereconsistentlyhighestinmangroveas theseelementsvariedinmagnitudebyyearandIsland.
Thesignificantdifferenceswereportamongyear classesinage-0Frenchgruntandschoolmasterotolith elementalsignatureswassimilartointerannualdifferencesinotolithchemistryreportedforothermarine fishes(Miltonetal.1997,Campana1999,GillandersandKingsford2000,Gillanders2005).Miltonetal. (1997)observedinterannualvariationinotolithchemistrybetweentwoestuarinepopulationsoftropical shad(Tenualosatoli).Shadcollectedin1994wereelevatedinMg,Cu,Zn,Sr,andBaanddepletedinLi comparedwithfishcollected1yearlater.GillandersandKingsford(2000)alsodetectedinterannual variationintheMn,Sr,andBacompositionofjuveniletrumpeter(Pelatussexlineatus)otolithsand suggestedthatthismayhavebeenaresultofvariationinfreshwaterrun-offwithinandbetweenyears.
Thediscriminantmodelsbasedonthehabitat-relateddifferences(i.emangrovevs.seagrass)classified juvenileswithahighdegreeofaccuracy(about92%).Thisconfirmstheuseofotolithtracemetalsand stableisotopesaseffectivetagsofthenurseryareaofjuvenileschoolmaster and FrenchGrunts.By contrast,theclassificationsuccessratesforthediscriminantfunctionsbystationswithinislandswasa littlelower(generally>85%).Thisindicatesthatitisdifficulttoseparate stationswithinsamehabitatsfor coastalstations:wefoundgreateroverlapsbetweenmangrovevsmangroveandseagrassvsseagrass stationswhiletherewasverylittleoverlapbetweenhabitatswhenalldatawerecombined.
Apossibleexplanationforerrorintheclassificationmodelsbystationisthatmisclassifiedfishhad recentlymovedintothecollectionhabitatfromtheadjacentalternativehabitattype(Chittaroetal.2005, 2006).Movementofindividualsbetweenmangroveandnon-mangrovecoastalhabitatspriortocapture wouldresultinachemicaltagthatwaseithertypicalofthealternativehabitattypeorofanintermediate valuedependingonthetimingofthemovement.Byexaminingtheperiodofrecentgrowthintheotolith
edgeandcomparing theelementalconcentrationsintheotolithsoffishinhabitatingthebackreefandthe onescapturedonthebackreefandtransportedtoaenclosedenvironmentinthemangroveforaperiodof twoweeks,Chittaroetal(2004)founddifferencesinelemental fingerprintsintheotolithedge(periodof recentgrowth)betweenFrenchgruntcapturedfromthebackreefandfishtransportedtoanenclosurearea inthemangroveinBelize. Thisstudyshowedthatthereweresignificantdifferencesinelemental conentrationsonotolithsoffishinhabitatingabackreefversusafishinhabitatingamangroveinBelize. However,ontheirfollowupstudy(Chittaroetal.2005,2006),theyfoundlowdiscriminationin mangroveandbackreefnurserygroundsbasedotolithchemistry(usingtheotolithedge)amongjuveniles FrenchgruntandschoolmasterinthesiteofcaptureinBelize.Withinstationdiscriminationsuccesswas about46%forFrenchgruntand40%forschoolmaster, and75%and67%forhabitatrespectively; considerablylessthanwhatwefoundeitherwithineachspeciesperstationbyisland(85%)andwithin eachspecieswithinhabitats(92%).Theyconcludedthatsomeindividualscollectedfrommangrove habitatsintheirstudymighthaverecentlymovedintothebackreefduringtheirnightfeedingmigration. Thediscriminantmodelwouldhavemisclassifiedtheseindividualsbecausetheirotolithswouldcontaina ‘non-mangrove’habitattag.Errorinclassificationoffishinthereefmayhavebeencausedbythe reversephenomena – fishcollectedonthebackreefmighthaveamangrovesignaturebecausetheymight haverecentlymovedtothemangrovesitesduringtheirnightfeedingmigration.
Ouroverallbetterdiscriminationprobablyreflectsthefactthatweusedthestableisotopes 13Cand 18Oin additiontotracemetalsaloneasusedbyChittaroetal(2005,2006),aswellasthefactthatweusedthe otolithregionofthepostettlementperiod.Atthisearlylifestage,bothspeciesfishwouldhaveasize about2-3cmFL.ThesizerangeoftheFrenchgruntscapturedinBelizewas7-14cm(Chittaroetal. (2005)whiletheaveragesizeofschoolmasterwas17.6cm(Chittaroetal.2006).Bymeasuringchemical compositionoftheotolithsatthesametimeinthedevelopmentofeachspecieswereducedpossible effectsoffactorssuchasgrowthandmovementthatmightmaskresultsinelementalfingerprints. Further,bydeterminingachemicalsignatureintheotolithsduringanearlylifestage,thediscriminatory powerwouldincreaseasthesesmallfishmaymoverelativelyshortdistanceswithinhabitats(<100m) resultinginacharacteristicrepresentationofthehabitatthattheyspendtheirpostsettlementperiod.
Severalauthorshaveshownthatstableisotopescanalsobeusedtotracetheoriginormovementof organismsbecauseisotopicsignaturesinanimaltissuesreflectthoseoflocalfoodwebsoroftheaquatic habitatinwhichtheyhavegrown.Isotopicsignaturesoffoodwebsorwatermassesvaryspatially dependingon biogeochemicalprocesses (Hobson1999,Kennedyetal.2000).Thecontributionofdiet versuswatertotheisotopicsignalislikelytodependontheisotope.Severalstudieshaveusedavariety ofstableisotopes (e.g. δ13C, δ15N, δ34S)toinvestigatemovementlargelyusingtissuesamples (e.g.Fry 1981,1983,Fryetal.1999),althoughseveralstudieshaveinvestigatedtheuseofstableisotopesin otoliths (Dufouretal.1998,Kennedyetal.2002,Augleyetal.2007,Huxhametal.2007,Verweijetal. 2008).Fry (1981) examined δ13Cvaluesintissuesofbrownshrimp Penaeusaztecus astheymovedfrom inshoreseagrassbedstooffshoreareas.Offshorehabitatswithaphytoplankton-basedfoodwebare depletedin 13Crelativetoaseagrassbasedfoodweb.Sub-adultindividualscollectedoffshorehad δ13C valuestypicalofindividualsinseagrassmeadows,suggestingthattheyhadmovedfromseagrassto offshoreregions
Studiesusingstableisotopesinhardpartssuchasotolithshavebeenfewer((Dufouretal.1998,Kennedy etal.2002,Augleyetal.2007,Huxhametal.2007,Verweijetal.2008).Thesehavetheadvantageinthat thesignatureisfixedatthetimethematerialislaiddownintheotolithandmaybeusedtoindicatepast historycomparedwithtissueswherethecompositionmaychangerapidlydependingondiet.Theutility ofusingstableisotopestodiscriminatebetweenhabitatswasdemonstratedbyHuxhametal.(2007) where 13CinotolithsasamarkerforfishbetweenmangroveandoffshorepopulationsinGaziBayKenya. Otolithsoffishfrommangroveshaddepletedvaluesof 13Cwhilethosefromoffshorewereenriched.In ourstudy,carbonisotopesprovedtobeparticularlyusefulindiscriminatingnurseryoriginsof
schoolmasterandandFrenchgrunts;fishotolithsfrommostofthemangrovestationswerecharacterized byconsistentlylowerlevelsof 13Cwhereasfishfromseagrasshadotolithsthatwereenrichedwith 13C. SimilarlyVerweijetal.(2008)showedevidenceofconnectivityandmovementbetweenseagrassand offshorereefsforyellowtailsnapper, Ocyuruschrysurus,in Curacao.Basedoncomparisonsofisotopic signaturesof 13Contheedgezoneoftheotolithsinjuvenileyellowtailsnappercaughtinseagrassand adultsontheouterreef,theyfoundthat 13 Cinotolithsofyellowtailsnapperwasmoreenrichedthan adultsfoundattheouterreef.
AreMangroveNurseryHabitatsforSchoolmasterandFrenchGruntsinSt.CroixandPuertoRico?
ThepercentageoftheFrenchgruntsubadultsthatwereidentifiedashavingresidedasjuvenilein mangrovehabitatswasestimatedtorangebetween40%and70%forSaltRiverSt.Croix,andLa Parguera,PuertoRicowhereasforschoolmasteralmost100%ofallfishresidedinmangrovehabitatsin bothIslands.WhenwescaleduptheseresultstotheirhabitatareasPuertoRico:([MangroveMontalva Bay=3.7km2 Seagrass=Corral1.5km2]AguilarandAppeldoorn(2007);StCroix[MangroveSalt River=0.12km2 SeagrassSaltRiver=0.21km2]Kendalletal2001,thecontributionperareaof Montalva-CorraltoadultFrenchgruntpopulationsinTurrumotewas0.2km-2 forbothseagrassand mangrovehabitats.ForschoolmasterthecontributiontoadultpopulationsinTurrumotewas0.24km-2 for mangrovehabitatsand0.067km-2 forseagrasshabitats.InStCroixthecontributionofFrenchgrunt per areaofseagrassandmangroveinSaltRivertoadultpopulationswas2.85km-2 forseagrasshabitatsand 3.3km-2 formangrovehabitats.ForschoolmasterthecontributionperareatoadultpopulationsinSalt Riverwas7.5km-2 formangrovehabitatand0.5km-2 forseagrasshabitats.Theseresultssuggestthat mangrovehabitatsintheseregionsmaybeactingas‘nurseryhabitats’bycontributingmoreindividuals perunitareatoschoolmastertoadultpopulationthantheadjacentcoastalhabitatswhereasforFrench gruntsmangroveandseagrassmaycontributinginsimilarproportionstotheadultspopulationsinthe regionsstudiedinStCroixandPuertoRico(Becketal.2001,Dahlgrenetal.2006)
Thedisproportionatecontributionofonejuvenilehabitattotheadultpopulationsmaybeduetofishin thathabitathavinghigherdensities,highergrowthrates,lowermortality,ormoresuccessfulrecruitment totheadultpopulation(Becketal.2001).PastresearchonschoolmasterandFrenchgruntsalongthe Caribbeancoasthasfoundevidencethatmangrovecansupporthigherdensities(Nagelkerken,etal.2000, CocheretdelaMoriniereetal.2002,AguilarandAppeldoorn,2007)andfastergrowthrates(Mateoetal. 2008)thannonmangrovehabitats.Inastudy usingotolithmicrostructure,Mateoetal.(2008)found highergrowthratesinmangrovethannonmangrovehabitatsforschoolmasterandFrenchgruntatthe postsettlementperiodinPuertoRicoandSt.Croix.Thesefindingssuggestthatmangrovehabitatsmay beproducingmorejuvenileschoolmasterandFrenchgruntbecausetheysupportahigherdensityoffaster growingfishthatsuccessfullyrecruittotheadultpopulation.
Evidencefordisproportionatecontributionoftropicalshallowwaterhabitats(i.e seagrass)toadultreef fishpopulationshaverecentlybeenfoundforonespeciesyellowtailsnapper Ocyuruschrysurus (Verweij etal.2008).Thesefindingscombinedwiththoseofthecurrentstudysuggestthatnearshorehabitatssuch asmangrovelagoons andseagrassmeadowsmaycommonlyfunctionasnurseryhabitatsforjuvenilereef fishpopulations.ManymangroveandseagrasshabitatsintheUSCaribbeanandworldwideare vulnerabletolossordeteriorationfromavarietyofprocesses,includingerosion,pollution,and urbanization.Conservationofthesenearshore‘nursery’habitatsmaybeanimportantstepinmaintaining highlevelsofrecruitmenttoharvestedreeffishpopulations.Tomorefullydeterminetheimportanceof nearshorehabitatstothemaintenanceofreeffishpopulationsinUSCaribbean,thecontributionof nearshorehabitatsshouldbedeterminedoveralargerspatialscale.Identifyingtheregionsinwhich disproportionatecontributionoccurswouldhelptodeterminewhichestuarinehabitatsshouldbetargeted forprotection.
CONCLUSIONS
Inthisstudy,wehavedemonstratedthatjuvenileschoolmasterandFrenchgruntfromdifferentnursery sitescanbedistinguishedbasedontheirotolithchemistrywithahighclassificationsuccess.Ourongoing researchwithotolithswillfocusonwhetherindividualsorconsecutiveyearclassesoffishresidinginthe samenurseriesmaintainaconsistentelementalsignature.Theultimateobjectiveistouselaserablation ormicromillingtechniquestolookatthejuvenilecoreregionofotolithsfromadultreeffishfrom adjacentoffshorereefsandseeiftheirelementalsignaturescanbeusedtodeterminetheoriginofthese fish.Althoughmoreinformationonthespatialandtemporalvariationinwater chemistryandthe relationshipbetweenambientwaterandotolithchemistryisneededtofullyinterpretotolithgeochemical signatures,thedatapresentedhereindicatethatotolithchemistryholdspromiseinstudiesonalongshore fishmovementandconnectivityamongshallowwaternurserygroundsandadulthabitatsforreeffish species.
ACKNOWLEDGEMENTS
WewouldliketothankHectorRiveraandWilliamTobiasfromDFW-St.Croix,fishermenJoseSanchez andGersonMartinez,andSt.CroixAnchorDivefor theirhelpandsupportinSt.Croix.Specialthanks goestoMichaelNemeth,TonyMarziak,HectorRuiz,MarcosRosadoandGodofredoMartinezfromthe UniversityofPuertoRico,andtoPedroCollazoforsupportforassistanceinPR.Wewouldalsoliketo thankDrs.RichardKingsleyandKatherineKelleyfortheirassistancewiththetracemetalanalysisatthe ICPMSlabattheUniversityofRhodeIsland,GraduateSchoolofOceanography,andDr.PeterSwartfor thestableisotopeanalysesatRSMAS.WewouldalsothankDrChrisWeidmanforassistanceintheuse oftheMicromillmachineoveratWHOI.SpecialthanksgotoDr.DaisyDurantforhelpwiththe graphicsandeditingofthismanuscript.ThisstudywasfundedthroughPuertoRicoSeaGrantProgram, PADI Foundation,andSigmaXi.
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TABLES
Table1.DetailsoftheLaserandICPMSusedinthestudy.
Laser
Wavelength 213nm
Mode Qswitched
Repetionrate 6Hz
Energy 0.9-1mJ
Spotsize 40µm
Mixingchamber He(0.36/min)
High ResolutionICP-MS
Resolution 300
Gasflow
Coolant 14/min
Auxiliary 1.55/min
Cone nickel
Detectionmodes Analogue(Ca,Sr)
Dwelltime 30s
Channels/peak 3(22%ofmasswindow)
Magnetsettlingtime 1msperamu+5ms
Table2.Sizedistributionbystation,habitat,andyearof H.flavolineatum and L.apodus.
StationsabbreviationsforSt.Croix:AL=AltonaLagoon,SR=SaltRiver,TB=TeagueBay,TH=Turner Hole,GP=GreatPond.
StationsabbreviationsforPuertoRico:CO=Corral,EL=ElPalo,ML=MariaLanga,MO=Montalva, GU=Pta.Guayanilla.
Island Species Habita t Statio
Island Species
Habita t Statio
Fishweremeasuredbyforklength(FL,cm).Numbersinparenthesisarestandarderror.
Table3.ResultsofMANOVAoftraceelementconcentrationandstableisotopiccompositionin otolithsofYOYof H.flavolineatum and L.apodus collectedinstationsinSt.CroixandPuertoRico.
MANOVAon[Sr/Ca],[Ba/Ca],[Cu/Ca],[Co/Ca],[Mg/Ca], 13C,and 18O.
MANOVAonmultielementalfingerprintson H.flavolineatum
Source
MANOVAonmultielementalfingerprintson L.apodus
Source
AllstatisticanalysisweredoneinLn(X+1)transformeddataandonPillaistatistic.
Table4.JackknifedClassificationSuccessusingLinearDiscriminantFunctionAnalysisfor H. flavolineatum otolithscollectedinSt.CroixandPuertoRico.
StationsabbreviationsforSt.Croix:AL=AltonaLagoon,SR=SaltRiver,TB=TeagueBay,TH=Turner Hole,GP=GreatPond.
StationsabbreviationsforPuertoRico:CO=Corral,EL=ElPalo,ML=MariaLanga,MO=Montalva, GU=Pta.Guayanilla.
- 2006
- 2007
Table5.ResultsofMANOVAoftraceelementconcentrationandstableisotopiccompositionin otolithsofYOYof H.flavolineatum and L.apodus collectedinstationsinSt.CroixandPuertoRico.
MANOVAon[Sr/Ca],[Ba/Ca],[Cu/Ca],[Co/Ca],[Mg/Ca], 13Cand 18O.
MANOVAonmultielementalfingerprintson H.flavolineatum.
Source Value F Numerator Denominator P
St.Croix
MANOVAonmultielementalfingerprintson L.apodus
A=StCroixB=PuertoRico
Source Value F Numerator Denominator P
AllstatisticanalysisweredoneinLn(X+1)transformeddataandonPillaistatistic.
Table6.JackknifedClassificationSuccessusingLinearDiscriminantFunctionAnalysisfor L. apodus otolithscollectedinSt.CroixandPuertoRico.
Stations abbreviationsforSt.Croix:AL=AltonaLagoon,SR=SaltRiver,TB=TeagueBay,TH=Turner Hole,GP=GreatPond.
StationsabbreviationsforPuertoRico:CO=Corral,EL=ElPalo,ML=MariaLanga,MO=Montalva, GU=Pta.Guayanilla.
- 2006
- 2007
Table7.UnivariateresultsoftheMANOVAof H.flavolineatum usingyearandstationasfactors. Source
Table8.UnivariateresultsoftheMANOVAof H.flavolineatum usingyearandhabitatasfactors.
Source
Table9.UnivariateresultsoftheMANOVAof L. apodus usingyearandstationasfactors. Source
St.Croix
Table10.UnivariateresultsoftheMANOVAof L.apodus usingyearandhabitatasfactors.
Table11.Percentofsubadultsoriginatingfrommangroveandseagrassbasedonmaximum likelihoodmodelstoassignsubadultstohabitatorigin.
- SaltRiver
PuertoRico - Turrumote,LaParguera
BasedondataSr,Ba,Mg,Cu,Na, 13Cand 18 Oinyear2007forjuvenilescapturedin2006. Percentofsubadultsoriginatingfrommangroveandseagrass
FIGURES
4.CanonicalScoresPlotsfor H.flavolineatum,St.Croix(top)andPuertoRico(bottom)for samplingyears2006and2007.
Figure
Montalva MariaLanga ElPalo Corral
5. CanonicalScoresPlotsfor L.apodus,St.Croix(top)andPuertoRico(bottom)for samplingyears2006and2007
Figure
Montalva
MariaLanga
ElPalo Corral
Figure6.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY H.flavolineatum collectedinSt.Croix(USVI)in2006and2007.Alltraceelement data[Element/Cax103]areLn(X+1)transformed.
SamplingYear
Figure7.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY H.flavolineatum collectedinPuertoRicoin2006and2007.Alltraceelementdata [Element/Cax103]areLn(X+1)transformed.
8.2
F=5.56,p=0.002
F=8.906,p=0.001
SamplingYears
Figure8.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredin otolithsofYOY L.apodus collectedinSt.Croix(USVI)in2006and2007.Alltraceelementdata [Element/Cax103]areLn(X+1)transformed.
SamplingYears
SamplingYears
Figure9.Spatialandtemporalvariabilityintraceelementsandstableisotopesmeasuredinotoliths ofYOY L.apodus collectedinPuertoRicoin2006and2007.Alltraceelementdata[Element/Cax 103]are Ln(X+1)transformed.
