长江口鱼类群落的多样性分析

根据2010年至2011年4个季度的底拖网鱼类资源调查资料,同时根据不同水域的盐度特征,将长江口的30个站位从河段水域至口外依次分为3个水域(Zone-1、Zone-2、Zone-3)进行分析,从构成群落的物种分类水平、丰度、二元数据和分类阶元4个角度首次探讨了长江口鱼类群落4个多样性指数(种类数目、Pielou均匀度指数、分类学多样性指数、平均分类学指数)的分布特征。结果显示,4个指数的季节变化均不显著。而种类数目和反映群落不同物种之间亲缘关系的平均分类学指数在空间上变化明显。平均物种数目由Zone-1(3.49种)至Zone-3(10.17种)的升高趋势反映出海洋对河口作用的逐渐增强;平均分类学指数的变化增加趋势说明Zone-1的物种亲缘关系最近,如Zone-1只记录8科鱼类,而Zone-2和Zone-3分别记录20和19科鱼类。虽然反映不同物种的个体数量分布特征的Pielou均匀度指数和反映群落不同个体之间亲缘关系远近的分类学多样性指数空间上差异均不显著,但它们却呈现相反的变化趋势。多样性指数的空间差异要大于季节差异,可能与盐度对河口区鱼类群落的分布影响最大有关。本研究通过长江口鱼类群落不同多样性测度的分析,证实不同多样性测度方法提供的信息不一致,旨在为更全面地分析河口区鱼类群落特征提供依据。

Fish community diversity analyses in the Yangtze River estuary, China

Estuarinesystemsareconsideredasatypicalecotone,andanestuarinefishcommunitystudyisconsideredtobeafundamentalecologicalresearchstudy.Fourfacets(numberofspecies,Pielouevenness,taxonomicdistinctnessandaveragetaxonomicdistinctness)ofcommunitydiversitycharacteristicsstructuringbyspecieslevel,abundance,binarydataandclassificationlevelswereanalyzedwithintheYangtzeRiverestuary,China,whichisdividedintothreezones(Zone1,Zone2,andZone3)alongtheestuarinegradient.Fishsamplingwasconductedusingbottomtrawlingseasonallyfrom20102011.Theresultsshowedthatallfourdiversityparametersdidnotdiffersignificantamongseasons.However,numberofspeciesandaveragetaxonomicdistinctnessbothdifferedsignificantlyamongthedifferentzones.AnincreasingtrendinmeannumbersofspeciesfromZone-1(3.49species)Zone-3(10.13species)wasrelatedtothestrongermarineinfluenceonthelatterzones.LowervaluesofaveragetaxonomicdistinctnessinZone-1suggestedthatmorespecieswerecloselyrelatedinZone-1thaninZone-2orZone-3,forexample,8,20,and19familieswererecordedinZone-1,Zone-2,andZone-3,respectively.Althoughspatialchangesintaxonomicdistinctnessandevennesswerenotsignificant,inversepatternsofthetwoparametersoccurred.Nevertheless,evennesspeakedinZone-1whereasmoreindividualswerecloselyrelatedinZone-1thaninZone-2orZone-3.Moreover,spatialpatternsincommunitydiversitywerestrongerthanseasonalvariations.Thismayreflectthatsalinityplaysthemajorroleindrivingtheestuarinefishcommunity.ThisworkanalyzedthefourfacetsofdiversityestimationsoffishcommunitywithintheYangtzeRiverestuary,andfurtherdemonstratedthatdifferentmeasuredparametersmayhighlightdifferentinformationregardingcommunitystructure,andwillbeusefulforassessingestuarinefishcommunitydiversity.