SPECIES DIVERSITY AND COMMUNITY STRUCTURE OF ZOOPLANKTON IN SUMMER AND WINTER IN THE EAST LAKE, WUHAN

This study investigated the zooplankton community in the East Lake in July, August, December 2018 and January 2019 and identified a total of 50 species of the zooplankton belonged to 35 genera, including 37 Rotifera belonged to 22 genera, 10 Cladocera belonged to 10 genera, and 3 copepoda belonged to 2 genera. The dominant species were Microcyclops varicans, Brachionus diversicornis, and Moina micrura in summer and Polyarthra dolichoptera, Synchaeta spp., Brachionus angularis, and Rhinoglena sp. in winter. The image information of all observed zooplankton was collected, and the SSU rRNA gene sequences of dominant species were determined to provide reference data for the identification of freshwater zooplankton. According to the historical data about zooplankton in Wuhan East Lake, the number of zooplankton species in the East Lake has decreased gradually in the past few decades, and the dominant species of rotifers have changed from oligosaprophyte to beta-mesosaprobity or even alpha-mesosaprobity. The zooplankton community structure in East Lake was significantly different in summer and winter. The rotifer density (56.2 ind./L) and biomass (0.2188 mg/L) in summer were lower than those in winter (476.3 ind./L, 0.4415 mg/L), while the crustacean density (137.8 ind./L) and biomass (2.8831 mg/L) were higher than those in winter (53.1 ind./L, 1.1187 mg/L). The Margalef richness index, Shannon-Wiener diversity index and Simpson diversity index of the zooplankton community in summer were higher than those in winter. The Pielou evenness index is not different between summer and winter. The water quality evaluation showed that the water quality in summer (moderately polluted) was better than that in winter (heavily polluted). There were significant differences in temperature, dissolved oxygen, pH, salinity and ORP between summer and winter. Redundancy Analysis (RDA) indicated that temperature had the greatest influence on zooplankton community structure.