Community characteristics of macrozoobenthos and its relationship to environmental factors in Lake Nansi

To understand the community characteristics of macrozoobenthos and its relationship to environmental factors in Lake Nansi,the species composition,inhabit density,biomass,dominant species,the conditions of aquatic plants and water quality were investigated in June 2010.There were 23 species of macrozoobenthos with the inhabit density of 311.57 ind./m2 and biomass of 44.39 g/m2.The dominance index was relative high,and the dominant species consist of Chironomus plumosus and Limnodrilus hoffmeisteri which were accounted for 77.45% and 11.39% of the total individuals,respectively.The biomass and coverage of aquatic plants were 1613 g/m2 and 33%,and there was no significant correlation between the biomass of aquatic plants and the community characteristics of macrozoobenthos.Lake Nansi was polluted majorly by nitrogen,next by phosphorus and finally by CODMn.The community characteristic of macrozoobenthos was not significantly correlated with the community characteristics of aquatic plant and with the water quality.The number of macrofaunal species was significantly negative correlated with the concentration of CODMn of water,and the inhabit density of macrozoobenthos was significantly positive correlated with the TLI(∑) of water in 2010.According to evaluation of Goodnight-Whitley index and TLI(∑),Lake Nansi has been in the state of clean and mesotropher,but serious pollution in some water areas.