为研究长江口鱼类群落分类学多样性值(平均分类差异指数△+与分类变异差异指数∧+)的长期变动,根据1985～1986年、2004年及2010～2011年3个时期共12个航次长江口鱼类调查资料,分别计算了反映鱼类群落不同物种亲缘关系△+和亲缘关系均匀性∧+值.结果显示,2004年4个航次及2010～2011年3个航次鱼类△+均位于长江口鱼类群落总名录△+95％置信区间以下,与1985～1986年相比,2004年及2010～2011年各航次平均△+均较低;∧+的分布格局则与△+有所不同,主要表现为12个航次的∧+均在95％置信区间内.长江口鱼类群落△+的降低跟过度捕捞、环境污染、生境破坏等有关,其下降也反映出群落种类组成在形态亲缘关系上更加接近.%For studying the long-term changes in taxonomic diversity (average taxonomic distinctness and variations in taxonomic distinctness) of fish community in Yangtze River estuary,fish species recorded at three periods (1985～1986,2004,2010～2011) were used to estimate the△+ and ∧ + for respective survey.The results showed that △+ in 2004 and 2010～2011 (except the spring survey) fell below the 95％ probability limits for △+ of all fish species from Yangtze River estuary.Moreover,the decreasing trends in △+ were also observed.However,patterns of variation in ∧ + was different from △+,as all ∧+ distributed in the 95％ probability limits for ∧ + of all fish species.Declines in △+ of Yangtze River estuary may be a result of overfishing,pollution and habitat destruction,as shown in closer relationships among fish species,implying for increased niche similarity between species and potential loss of stability or resilience of the community.
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