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简介：ThespatialandtemporalcharacteristicsoftrophicstructureoffishcommunitiesinthesouthernHuanghaiSeawereexaminedbasedonthedatasampledfrombottomtrawlsurveysconductedduringtheautumnof2000andthespringof2001.HierarchicalagglomerativeclustermethodandbootstraprandomizationwereusedtoidentifysignificanttrophicgroupsforeachfishassemblageinthesouthernHuanghaiSea.Atotalofsixmajortrophicgroupswereidentifiedwithinthissystem,whichclassifiedpredatorsbaseduponlocationinthewatercolumnorpreysize(i.e.,benthictopelagicpredatorsorfishtosmallinvertebratepreypredators).Thesimilaritylevelusedtoidentifysignificanttrophicgroupsineachassemblagerangedfrom24%to34%.Althoughplanktivoreswerethedominanttrophicgroupineachassemblage(60%~79%),therewerespatialandtemporalvariationsinthetrophicstructure,whichreflectedthedifferencesintheabundanceandavailabilityofdominantpreys.Simplifiedfoodwebswereconstructedtoevaluatethemostimportanttrophicrelationshipsbetweenthedominantpreytaxaandthefishesineachassemblagewithinthissystem.Althoughthereweresomedifferencesinthekeypreyspeciesamongdifferentfoodwebs,pelagicpreyitems(mainlyeuphausiidsandcopepods)representthemostimportantenergeticlinkbetweenprimaryproducersandhighertrophiclevelpredators.Thetrophiclevelformostfisheswasbetween3and4,andtheweightedmeantrophiclevelforeachassemblagerangedfrom3.3to3.4.Comparedwithpreviousstudyinthemid-1980s,therewasanobviousdownwardtrendinthetrophiclevelformostfishspecies,whichresultedmainlyfromthefluctuationinkeypreyspeciesintheHuanghaiSea.ThedecreaseintheimportanceofJapaneseanchovyseemstobeoffsetbyotherabundantpreyspeciessuchasEuphausiapacificaandcopepods(mainlyCalanussinicus).

简介：aquaculturedApostichopusjaponicus的食物来源和在一条海黄瓜的有机体的营养的层次(一。japonicus)并且对虾(Penaeus装饰用的梨树)在Zhuanghe的一个盐水的池溏里的polyculture系统，辽宁省被检验使用碳和氮马厩同位素。越过有机体，13C从(-25.47d反应表面方法，水温度的联合效果(18-34栠杩?潨潭潬祧眠瑩?湫睯?湩敶瑲'O慲整洠汵楴爭灥慥?琭票潭楳獮

简介：Asapexpredators,sharksareofecologicalandconservationimportanceinmarineecosystems.Inthisstudy,trophicpositionsofsharkswereestimatedusingstableisotoperatiosofcarbonandnitrogenforfiverepresentativespeciescaughtbytheChineselonglinefleetinthemid-eastPacific,i.e.,theblueshark(Prionaceglauca),thebigeyethreshershark(Alopiassuperciliosus),thesilkyshark(Carcharhinusfalciformis),thescallopedhammerhead(Sphyrnalewini),andtheoceanicwhitetipshark(Carcharhinuslongimanus).Ofthesespecies,oceanicwhitetipsharkhasthelowesttrophiclevelandmeanδ15Nvalue(3.9and14.93‰±0.84‰),whereasbigeyethreshersharkhasthehighestlevel/values(4.5and17.02‰±1.21‰,respectively).Thebigeyethreshersharkhassignificantlyhigherδ15Nvaluethanothersharkspecies,indicatingitshighertrophicposition.Thebluesharkandoceanicwhitetipsharkhassignificantlyhigherδ13Cvaluesthanbigeyethreshershark,silkysharkandscallopedhammerhead,possiblyduetodifferentdietsand/orlivinghabitats.Thestableisotopedataandstomachcontentdataarehighlyconsistent,suggestingthatstableisotopeanalysissupplementstraditionalfeedingecologystudyofsharks,andthuscontributestounderstandingtheirtrophiclinkage.