| The health of river ecosystem is significant for the sustainable development of human society.Pollution of streams is recognized as one of the most important environmental problems in the world.Many studies have shown that contamination of streams affects river ecosystem and human health.Macroinvertebrates,an important part in the freshwater ecosystem,plays a key role in the water ecosystem.It has practical significance to understand the structure and function of the ecosystem.Macroinvertebrates,which has a relatively stable living area and long life-cycle,show a variety of ecological functions.Due to its sensibility to pollutants,macroinvertebrates can indicate environmental change in local conditions.It is also widely used in biological assessment.Therefore,carrying out research on community structure of macroinvertebrates and river health assessment has practical values to the protection and sustainable utilization of rivers in China.Based on this,this study carried out a comprehensive research on zoobenthos of four rivers in Hainan Island and Guangxi Zhuang Autonomous Region.The main results are as follows:(1)102 species belonging to 58 family,9 class,5 phylum were recorded in Wanquan River,among which,there were 5 species of Oligochaeta,67 species of Aquatic Insect,19 species of Mollusca and 11 other species.(2)128 genera of zoobenthos were collected in six input rivers(Nankai River,Nanmei River,Nanxi River,Nancha River,Nanwan River and Nanchun River)of Songtao Reservoir,in which 120 genera,61 family,8 class,5 phylum,were collected during dry season,94 genera,50 family,5 class,3 phylumwere collected during normal season,and 84 genera,45 family,6 class,3phylum were collected during wet season.(3)45 species were recorded in Diaojiang River in winter,among which,there were 3species of Oligochaeta,33 species of Aquatic Insect,5 species of Mollusca.58 species were recorded in Diaojiang River in spring,among which,there were 49 species of Aquatic Insect,6 species of Mollusca and 3 other species.(4)64 species belonging to 58 family,8 class,4 phylum were recorded in Longjiang River.Insecta contributed 45.3% of the total richness,with Chironomidae(26.6%,17 taxa overall)as the taxonomically richest group.Oligochaeta and Gastropada contributed 25% and 15.6% of the total richness,respectively.(5)In this study,the integrated index of diversity of macroinvertebrates is used to assess the watershed ecosystem health.Data indicated a high biodiversity in input rivers of Songtao Reservoir.In three different periods,biodiversity index appears to be almost the same.Ecosystem was excellent in the dry season and the normal season,and was good in the wet season.Results showed that the biodiversity in the whole basin of Wanquan River was high.Three rivers were in good condition and three other rivers were in general status.Wanquan River and six input rivers of Songtao Reservoir are in good health condition.(6)Each site of Diaojiang River was placed into one of four metal categories(background,low,medium,and high metals).Differences among metal categories were highly significant for most measures of macroinvertebrate abundance and all measures of species richness.(7)Results showed that many metrics were increased with the time after heavy metal pollution,insect taxa number,total taxa number,taxa richness per samples,cumulative taxa number and Shannon-Wiener diversity index significant positive correlation with time after metal pollution event. |
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