Effects of fluvial processes and human activities on stream macro-invertebrates |
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| Authors: | Xue-hua DUAN Zhao-Yin WANG and Meng-zhen XU PhD State |
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| Institution: | Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China; Jiangyin Water Conservancy and Farm Machinery Bureau,Jiangyin 214431 China, 2 Prof,State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China, 3 Doctoral candidate,State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China, |
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| Abstract: | Benthic macro-invertebrates are vital components of river ecosystems.The effects of fluvial processes and human activities on the distribution of macro-invertebrates were studied through field investigations and experiment.Sixty-one sampling sites on 31 rivers in China were selected to investigate the structures of macro-invertebrate assemblages.The rivers,according to their fluvial conditions,are classified as streams with a stable channel bed,degrading channel bed,aggrading channel bed,and intensive bed load motion.The structures of macro-invertebrate fauna for the four types of rivers are very different.Stable rivers have a large number of individuals,abundant fauna, and high biodiversity;while the density and taxa richness for degrading rivers are small,and those for aggrading rivers are much less;whereas the ecology of rivers with intensive bed load motion are the worst.This paper proposes that streambed stability is the primary influential factor shaping the structure of benthic macro-invertebrate communities.Organic pollution can obviously result in the decrease of biodiversity,in the simplification of macro-invertebrate structures,and in the distortion of functional feeding group composition.In a river with high total nitrogen content,the relative abundance of collector-gatherers is high,and that of collector-filterers,scrapers,shredders,and predators are low.Scrapers,shredders,and predators disappear in severely polluted rivers.The isolation of aquatic habitat results in a distinct decrease of individual numbers and taxa richness.This result demonstrates that the connectivity of aquatic habitat significantly affects macro-invertebrate assemblages.A practical method to calculate a Habitat Suitability Index(HSI) is proposed,integrating the effects of the primary physical(including biotic and abiotic) and chemical factors.The biodiversity and taxa richness increase non-linearly with HSI. |
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| Keywords: | Macro-invertebrate Streambed stability Substratum Isolation Habitat suitability Water pollution |
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