长江口鱼类群落的多样性分析

Fish community diversity analyses in the Yangtze River estuary,China

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。

Estuarine systems are considered as a typical ecotone,and an estuarine fish community study is consid-ered to be a fundamental ecological research study.Four facets（number of species,Pielou evenness,taxonomic distinctness and average taxonomic distinctness） of community diversity characteristics structuring by species level,abundance,binary data and classification levels were analyzed within the Yangtze River estuary,China,which is divided into three zones（Zone 1,Zone 2,and Zone 3） along the estuarine gradient.Fish sampling was conducted using bottom trawling seasonally from 2010–2011.The results showed that all four diversity parameters did not differ significant among seasons.However,number of species and average taxonomic distinctness both differed significantly among the different zones.An increasing trend in mean numbers of species from Zone-1（3.49 species）–Zone-3（10.13 species） was related to the stronger marine influence on the latter zones.Lower val-ues of average taxonomic distinctness in Zone-1 suggested that more species were closely related in Zone-1 than in Zone-2 or Zone-3,for example,8,20,and 19 families were recorded in Zone-1,Zone-2,and Zone-3,respec-tively.Although spatial changes in taxonomic distinctness and evenness were not significant,inverse patterns of the two parameters occurred.Nevertheless,evenness peaked in Zone-1 whereas more individuals were closely related in Zone-1 than in Zone-2 or Zone-3.Moreover,spatial patterns in community diversity were stronger than seasonal variations.This may reflect that salinity plays the major role in driving the estuarine fish community.This work analyzed the four facets of diversity estimations of fish community within the Yangtze River estuary,and further demonstrated that different measured parameters may highlight different information regarding com-munity structure,and will be useful for assessing estuarine fish community diversity.