Community structure of zoobenthos in spring and their application to bioassessment of water quality in Taihu Lake Watershed

Abstract

The macrozoobenthic assemblages in 7 reservoirs,8 rivers,and 14 lakes of Taihu Lake Watershed w ere investigated in May,2010. Totally,57 species,belonging to 8 classes,representatives of 4 phyla,w ere collected. Of those,Insecta( 17 species) and Oligochaeta( 15 species) w ere the most abundant in species number. As a w hole,the zoobenthic assemblage in this w atershed w as predominated by Limnodrilus hoffmeisteri. According to cluster analysis( CA),there existed 10 community types in the selected 29 w ater bodies,15 of w hich w ere prevailed by L. hoffmeisteri and 5 of w hich by Bellamya aeruginosa. The mean density and biomass in the w hole basin w ere 2741. 2 ind / m2and 47. 2 g / m2,respectively. Oligochaeta was predominant in density( about 91%),and Bivalvia together w ith Gastropod contributed about 93% of the total biomass. Among the different w ater body types,there w ere marginally significant or conspicuous differences in density w ith the maximum for river and the minimum for reservoir,and in biomass w ith the maximum for lake and the minimum for reservoir. Meanw hile,the numerical composition of macrozoobenthic groups( i. e. at the taxonomic level of class) differed obviously betw een the w ater body types. Although Shannon-Weaver diversity index( H') w as conspicuously correlated w ith richness( species number,S),H'w as more strongly governed by evenness( J). H',J,and Margalef species richness( R) in lake and reservoir w ere all significantly higher than those in river,respectively,and S did marginally conspicuously. The density in lakes w ith practice of aquaculture w as significantly higher than in ones w ithout. The reverse w ere found for biomass,H',and J. According to BPI index and H',the most stations of lake and river w ere moderately or seriously polluted,and the most reservoirs w ere clear or slightly polluted based on Wright index.