Characteristics of Community Structure of Plankton in Mianhuatan Reservoir

Aims of this study were to explore plankton community structure in Mianhuatan Reservoir after Zijin copper accident and to provide a reference for protecting ecological environment,improving the utilization efficiency of the water,and recovering the production order and the reasonable ecological structure in the waters.22 sampling points were set according to the water body environment and the situation of pollution.The density and biomass of plankton in Mianhuatan Reservoir were estimated.Results indicated that:6 phyla,35 genus and 43 species of phytoplankton were observed;densities and biomasses of phytoplankton were respectively 14.16×104-131.66×104 ind./L and 0.096-7.174mg/L;the mean density and mean biomass were respectively 42.89×104 ind./L and 1.401mg/L;the biomass and density of phytoplankton presented a trend of gradual decline from top to bottom.The diversity index fluctuated from 0.628 to 2.671,and the evenness index was in the range of 0.231-0.839.The Mianhuatan Reservoir mostly were in mild contamination,according to the evaluation standard;there were 4 phyla,13 kinds of zooplankton in the waters with densities 36-285 ind./L,the mean density 79 ind./L,biomasses 0.154-3.110mg/L,and the mean biomass 1.421mg/L;the diversity index and evenness index were respectively 1.300-2.441 and 0.625-0.982.The diversity indices of phytoplankton and some other data showed that Mianhuatan Reservoir was a middle nutrition reservoir and the plankton community structures of a part of this reservoir were unstable and susceptible to the outside interference.