THE RESEARCH OF DYNAMIC SUCCESSION OF ZOOPLANKTON AND ITS CORRELATION WITH ENVIRONMENTAL FACTORS IN TAIPING LAKE

The community characteristics and distribution of zooplankton in Taiping Lake were investigated from November 2012 to October 2014. The study identified a total of 89 species of the zooplankton belonged to 45 genera, including 69 Rotifera belonged to 29 genera, 7 Cladocera belonged to 5 genera, 4 Copepoda belonged to 2 genera and 9 Protozoa belonged to 9 genera. The dominant species were the Rotifera (Trichocereca) and (Keratella). We found the variability of spatial and temporal distribution of zooplankton abundance in Taiping Lake with the maximum of 1326 ind./L in summer and the minimum of 216 ind./L in winter while in spring and autumn they were 608 ind./L and 605 ind./L respectively. The vertical distribution of zooplankton abundance in water body showed that the surface abun-dance had the highest concentration, followed by the middle layer and the bottom layer in spring and summer, while the middle layer had the highest abundance in autumn and winter. Both Shannon-Wiener diversity index and Margalef abundance index suggested that the middle layer was generally higher than the surface and bottom, while Pielou index indicated that the bottom layer had the highest one in all three layers. All the diversity indexes suggested significantly higher value in summer and fall than that in spring and winter, and the water quality in summer and fall was better than that in spring and winter. The cluster analysis and multi-variate analysis revealed that zooplankton can divide into spring-winter group and summer-fall group, and there were comparatively big differences in zooplankton community structure from the central area to upstream and downstream of Taiping Lake with more obvious differences in the spring-winter group. The correlation and stepwise regression analysis displayed a significant relationship between zoo-plankton community and environmental factors. These results indicated that the transparency and the water tempera-ture were the main environmental impact factors in regulating zooplankton community structure in Taiping Lake. Structure Equation Modeling (SEM) and Redundancy Analysis (RDA) indicated that zooplankton abundance was higher in habitats with high temperature and dissolved oxygen, and that the temperature had bigger influence on Rotifera than on Cladocera and Copepoda.