STRUCTURE OF BENTHIC MACROINVERTEBRATE COMMUNITY AND ASSESSMENT OF WATER QUALITY IN KUILEI LAKE

Seasonal investigations on benthic macroinvertebrates were carried out in Kuilei Lake in 2008,the main drinking water supply source of Kunshan City,Jiangsu Province.Altogether 66taxa were identified from fifteen sampling sites.Among them were 18taxa of oligchaetes,26taxa of chironomids,14taxa of mollusks and 8forms of miscellaneous animals.Kuilei Lake was partitioned into four macrobenthic zones by Hierarchical Cluster Analysis.Densities of benthic macroinvertebrates were higher in southwest of Kuilei Lake(zone III and IV)than those in central and the northeast of the Lake(zone I and II).According to the wet weight,mollusks were dominant.Canonical correspondence analysis(CCA)was applied to explore the importance of environmental variables in influencing macroinvertebrate community structure.DO and TP were the key predictors of the community variance.The water quality was assessed using Shannon-Wiener diversity,Family Biotic Index and Biotic index,and totally it was polluted during the sampling period.The water quality of the outlet of Kuilei Lake(zone V)was least polluted,while inlet of Kuilei Lake(zone VI)was most polluted.Considering the coincidence with physical-chemical parameters,BI bioassessment methods were fitter to apply in this region.