东江大型底栖动物群落结构特征调查

Macrozoobenthos in the Dongjiang River were investigated in April to June 2012.Altogether 78 speciesbelonging to 7 classes, 48 families,72genera were recorded ,of which were 12 species of oligochaetes, 17 species of molluscs ,47 species of aquatic insect, and 3 other species .The dominant group in the upstream and source area were aquatic insect,comprising 70.2% and 58.3% of the total in density. While in the downstream oligochaetes was the main species, account for 62.0%. Tributaries of source of Dongjiang river, upstream, midstream and downstream of the number of species were 48 species, 31 species, 33 species and 28 species, respectively. Dominant groups show significant differences with the different degradation gradient segment. In upstream less anthropogenic interference with the river, the dominant species were low tolerance values of sensitive populations. The downstream estuarine pollution level is getting higher, dominant species was Limnodrilus sp.. The standing density of macrozoobenthos in downstream reach was significantly higher than other regions, the dominant speices was oligochaetes.The standing biomass of benthos in upstream was the most, the dominant group was mollusca. Compared with previous studies, the decline in the number of benthos species, should strengthen the ecological environment in the region of concern.