Relationship between Community Structure of Zooplankton and Water Quality of a Mesotrophic Lake Wetland

In order to explore the regular pattern of community succession of zooplankton and the influencing factors in the middle eutrophic reservoir, a systematic investigation was made to the zooplanktons in Baguishan Reservior from February to November in 2016, including the diversity, abundance, biomass of zooplanktons and environmental factors. The water eutrophication level was evaluated by using trophic state index （ TLI ）, and Redundancy Analyses （RDA） was employed to build dynamic changes of structure of protozoa, rotifer and crustacean. Finally, a total of 40 samples were collected. A total of 96 species of zooplankton were identified, including 41 species of protozoa, 34 species of rotifers, 12 species of cladocerans, and 9 species of copepods. TLI varied from 42.8 to 48.9 with an annual average of （45.07±2.02）, indicating that reservoir belonged to mesotrophic water body. Furthermore, Shannon-Wiener biodiversity （ H ′） and Pielou evenness（ J ） showed that the water quality of the Reservoir was β -pollution pattern. The results of RDA showed that the zooplankton community structure changed significantly with months. Chlorophyll a （Chl.a）, water temperature （WT） and ammonia nitrogen （NH 3-N） were the main factors influencing the community of protozoa, and Chl.a, WT, pH, NH 3-N and the ratio of NH 3-N to total phosphorus （TP） were important factors to rotifer community. The changes of crustacean community could be better explained by the factors of TP and WT, pH, and the ratio of NH 3-N to TP.

Relationship between Temporal and Spatial Variation of Planktonic Diatom Community Structure and Water Quality in Mesotrophic Reservoir

In order to clarify the regular pattern of community succession of planktonic diatoms and the relationship between the diatoms and the physic-chemical parameters, the species, abundance, and biomass of planktonic diatoms, and environmental factors in Baiguishan Reservoir （BGR） were investigated in Baiguishan Reservoir from February to November in 2016. Trophic state index （ TLI ） was used to evaluate the trophic state, and factors affecting the dynamics of planktonic diatom community were analyzed by Redundancy analyses （RDA）. The results showed that Baiguishan Reservoir belonged to mesotrophic water body, and all observed phytoplankton belonged to 69 genera of 25 families. The sampling points were divided into the same 2 groups in the clustering analysis based on environmental factors and Non-metric Multi-Dimensional Scaling （NMDS） analysis, indicating that the community structure of planktonic diatoms had the same change trends with the changes of environmental factors. RDA showed that the main factors affecting community structure were total phosphorus （TP）, water temperature （WT） and the ratio of ammonia nitrogen to total phosphorus （NH 3-N/TP）. Therefore, TP was the most important factor influencing the dynamics of planktonic diatom community in mesotrophic reservoir.