Preliminary Study On Feeding Behaviour Of Two Representative Species In Typical Habitats (seaweedbed&musselfarm) In Gouqi Island: The Gastropod, Turbocornutus Solander;the Mussel, Mytilusedulis

Stableisotopeexperiments、Fieldandlaboratoryexperimentstracedthefeedingbehaviorsofonemarineherbivore,thegastropod, TurbocornutusSolander,liveonthelowerintertidalrockyreefseaweedbedatGouqiIsland, ZheJiang,China.Inordertotracethepotentialfoodresource,stablecarbonandnitrogenisotoperatioswereanalysedinthetissueofTurbocornutusSolander,15differentseaweeds, phytoplankton, POM, andSOM.Isotopicratioδ15NsuggestedthattheaveragetrophiclevelofTurbocornutusSolanderis2.12.StableisotopeexperimentsdemonstratedthatTurbocornutusSolanderpreferredseaweed（＞94.5%） thanotherbait(suchasphytoplankton, POMandSOM).LaboratoryinvestigationsrevealedthatT. Solanderwasabletofeed11differentseaweeds,suchasLaminariajaponcicaAresch、 Sargassumhorneri (Turn.) Ag.、ChondriacrassicaulisHarv.andetc (＞0.1gwetweightoffoodindividual-1day-1).Incontrast, T. Solanderwasunabletofeed4typesofseaweed: Codiumfragile (Sur.) Hariot,CorallinaofficinalisL., Janiadecussato-dichotomaandHypneacervicornisJ.Ag(＜0.1gwetweightoffoodindividual-1day-1).Largeindividuals (wetweight≥50g)havesignificantlyhigherconsumptionratethansmallindividuals(wetweight＜50g).Size-fractionateofdigestedfoodwasteproductsexperimentsprovidedevidenceforchangeofsize-fractionateafterT. Solander’sfeeding. T. Solandercandigestseaweed,excretesmallersizeofdetritus,avariablesize-fractionateofwastefragmentsrangingfrom0μmto1000μmandfragmentsfrom250μm-1000μmcountedthemostproportionoftotalamountofdetritus(＞50%).Amorphologicaladvantage,detritusprovidedbyalargeindividualperdaywassignificantlymorethanasmallindividual,butratiosofdifferentsize-fractionatewasnotsignificantbetweendifferentbodysize. Thissuggeststhepossibilityofsize-fractionateofdetritusproducedbyT. Solander.Thearticlealsoconcludea4stepsmethod(usingStableisotopeexperiment—singlechoicefeedingbehaviorexperiment—multi-choicelaboratoryfoodpreferringexperiment—Size-fractionateofdetritusanalysis)toinvestigatethefeedingbehavioroforganismandtheirinfluencetowardstheecosystem.Investigationonphytoplanktonassemblagesandsize-fractionatewerecarriedoutinartificially-musselfarmintheGouqiIslandusingphytoplanktontrammelnetsin2012,inordertofindouttheroleofphytoplanktoninsupportinglocalphytoplanktondiversityandartificially-musselfarm.Phytoplanktontaxonomiccompositionandecologicalguildgroupswereusedtoexaminespeciescompositionindetail. IndicessuchasMargalef’sspeciesrichnessindex,Pielou’sspeciesevennessindexwereusedtoanalyzethestatusofphytoplanktondiversityinartificially-musselfarm. Atotalof43algaes, belongingto4classes,28familiesand40genera, werecollected. thirtyphytoplanktonfromtheDiatoms (accounting75%ofthetotalspecies), tenPyrrophyta (25%ofthetotalspecies) and15redtidephytoplankton(37.5%ofthetotalspecies) werecaptured.ThedominantspeciesareCoscinodiscusgranii,Oscillatoria,LeptocylindrusdanicusCleve, Biddulphiapulchella,Pseudo-nitzschiapungens.Itwasfoundthatthetotalabundanceshowedobviousregionalvariations,Theabundancevaluesfromtheoff-nearshoreshowingadownwardtrend.Itpeakedwithavalueof22.85×104cell m-3andthelowestabundanceoccurredinmiddleofmussel-farmingarea(3.14×104cell m-3).MDSanalysissuggeststhatphytoplanktonwillbedividedintotwobiologicalcommunitybythemidlineofmusselfarmwhilemussel’sfliterfeedingwasfoundtobeamajorinfluencingfactor.Thedistributionofsize-fractionedphytoplanktonwasalsodiscussedaswellasthecorrelationsofthesize-fractionatedwiththemussel’sfliter-feedingbehavior.Therangeofthesize-fractionatedofphytoplanktoninthisareawasfrom11.75μmto724.71μm.Closerelationshipswerefoundamongtheresultsofclusteranalysisofallstationsbasedonsize-fractionatedanddistancefromtheboundaryofmusselfarm,thedistributionofwatercurrentsandtheareadifferenceshowedbythesatelliteoceancolorrem otesensingimage.Theaveragesize-fractionatedinthemusselfarmishigherthantheareasurroundingit,asphytoplankton’ssize-fractionatedbelow60μmismorelikelytobethebaitofmusselfarmingearlystage(‘seed’).Wesuggestthatmoreattentionshouldbepaidtothephytoplanktoncommunityandthesize-fractionatedofphytoplankton, theymayaffectwiththemusselcarryingcapacity,assessmentofcarbonsequestration. Also,fliter-feedingofmusselcancontributetoprotecttheseaareafromredtide.