Relationship between Macro-Invertebrates and Water Qualities in Beijiang Watershed

The relationship between macrobenthos and 12 water quality factors in Beijiang River Basin was studied by Canonical Correspondence Analysis (CCA). The species-environment correlation was higher than 95%, which indicated the distribution of macrobenthos in Beijiang River Basin was strongly affected by water quality factors. Temperature, pH, conductivity, COD and SiO3-Si were the five major factors affecting the macrobenthos ecological distribution. Cl-, NH4-N and TN were also influential on the distribution of the macrobenthos to some extent. A total of 46 macrobenthos species were collected during the research period. Different species adapted to different ecological environment, and every kind of species had strong correlations with distinctive water quality factors. Indicated by macro-invertebrates, water quality was different from river to river in Beijiang River Basin. The water quality in midstream and downstream of Suijiang is good and little pollutants can be found. Water in mainstream of Beijiang had been contaminated by organic pollutants. And other tributaries located in upstream of Beijiang hadnt been affected significantly by pollutants.