长江中下游湖泊大型底栖动物群落结构及多样性

Community structure and biodiversity of macrozoobenthos of typical lakes in the middle and lower reaches of the Yangtze River

2007年10月至2008年4月,对长江中下游地区四种不同类型(草型、天然养殖、施肥养殖以及城市湖泊)的10个湖泊的大型底栖动物群落结构和多样性进行研究,并分析其与水体营养状态之间的关系.研究结果表明,不同类型湖泊底栖动物的密度、生物量、多样性及特征种类均存在显著差异.草型湖泊具有最高的生物量和多样性,但密度最低,其特征种类为腹足纲动物.天然养殖湖泊生物量也较高,物种多样性处于中间水平,特征种类为河蚬、寡鳃齿吻沙蚕及苏氏尾鳃蚓.施肥养殖湖泊和城市湖泊底栖动物密度较高,并呈现出最低的物种多样性,特征种类主要是耐污能力较强的颤蚓类和摇蚊科幼虫.相关性分析表明湖泊营养状态指数与底栖动物密度呈显著正相关,而与生物量呈显著负相关,说明随着营养水平的增加,底栖动物群落逐渐被小个体的耐污种类所主导.Margalef丰富度指数及Pielou均匀度指数与营养状态指数亦呈显著负相关,反映目前长江中下游湖泊随营养水平增加底栖动物群落趋于简单化的演替趋势.

Community structure and biodiversity of macrozoobenthos and their relationships with trophic state were investigated between November 2007 and April 2008 in 10 shallow lakes,including four types of macrophyte-dominated lakes,natural cultured lakes,artificial cultured lakes and urban lakes,in the middle and lower reaches of Yangtze River.Univariate and multivariate analysis showed that density,biomass,diversity and characteristic species differed significantly among the four type lakes.Macrophyte-dominated lakes had the highest biomass and biodiversity and the lowest density,and were characterized by gastropods.Natural cultured lakes are intermediate diverse communities and were characterized by Corbicula fluminea,Nephtys oligobranchia and Branchiura sowerbyi.Artificial cultured lakes and urban lakes presented the highest density and the lowest diversity and were dominated by pollution-tolerant species （e.g.tubificids and chironomids）.Correlation analysis revealed that trophic state index （TSI） was correlated positively with the density,whereas associated inversely with biomass,which indicated that small-size pollution-tolerant species became more dominant with increasing of trophic state.Diversity indices of Margalef and Pielou showed significantly negative correlations with trophic state index,implying the simplification of macrozoobentho communities with eutrophication in shallow lakes in the middle and lower reaches of Yangtze River.