|Other Abstract||1.Macroinvetebtate communities were studied, and the results showed that the inhabit environment in Jiuchong River was the best, followed by Xiangxi River, Gaolan River and Gufu River. Among the seasons, winter was the best for macroinvertebrates, followed by spring and autumn, and worst in summer. By canonical correspondence analysis (CCA), we found that the environmental factors impacting the macroinvertebrate communities were clearly different among different rivers and seasons.
2.Indices based on functional feeding groups were used to evaluate Xiangxi River system, the results showed that material cycling capability in Jiuchong River was much better than the other rivers, and in winter was much better than the other seasons. Longitudinal transport capability was the best in Gaolan River; and in winter was better than the other seasons. Lateral input capability in Jiuchong River was much better than the other rivers, and in winter was distinctly better than the other seasons. CPOM input/FPOM input was also better in Jiuchong River and in winter.
3.The niche was analysed, and the results showed that Baetis sp., Epeorus sp., Serratella sp., Antocha sp., Heptagenia sp. had broad niche breadths；Tetropina sp., Nemoura sp., Simulium sp. had narrow niche breadths. The total niche overlaps of Baetis sp., Epeorus sp., Serratella sp., Antocha sp. with others were high, while Simulium sp., Nemoura sp., Orthcladius sp., Tetropina sp. were low.
4.Macroinvertebrate communities were significantly affected by acid mine drainage from pyrite about 16 km downstream of the mine water discharge point. Protohermes sp., Baetis sp., Cheumatopsyche sp., Ceratopsyche sp., Neochauliodes sp., Polypedilum. tritum, Polypedilum. illinoense, Apedilum sp., Tretonia sp., Limnophyes sp., Rheopelopia. paramaculipennis, and Eukiefferiella. brehmi were tolerant of both acid and heavy metals.|