The Diversity and Distribution of Chironomidae from Shallow, Trophic Lake Chaohu, Southeast of China

The chironomid compositions and spatial configuration were first assessed through the analysis of 41 surface sediment samples from Lake Chaohu. Chionomid assemblages were mainly dominated by Microchironomus tabarui, Chironomus plumosus, Microchironomus and Harnischia, denoting totally eutrophicated conditions throughout the whole lake. Hierarchical cluster analysis and MDS (non-metric multidimensional scaling) ordination analysis categorized all sampling sites into three groups. The difference of fauna diversity and evenness index (i.e., H, d and J) among the three clusters were not statistically significant. Common taxa in individual samples showed high similarities (72.5-93.3%) with total chironomid fossils in the basin. The resuspension and redistribution of sediments might not enough to bring about the fully homogenization of chironomid remains. Effective explanation for the even distribution of chironomid was the totally eutrophication in the whole lake. The rapid and accurate response of organism communities to environment changes in habitats confirmed the importance of biological monitoring. The researchers should pay more attention to evaluation results just based on chemical proxy which may not reflect the real situation of aquatic systems. Comprehensive counter measures should be carried out for improving water quality in Lake Chaohu.