[Spatio-temporal Distribution Characteristics and Driving Factors of Zooplankton in Hongze Lake].

Hongze Lake is the fourth largest freshwater lake in China and is an important source of water for surrounding industrial and agricultural processes and fishery resources. Analyzing the changes in the zooplankton community structure in Hongze Lake can provide scientific support for the scientific management of its ecology and environment. A one-year monthly monitoring study was conducted from March 2017 to February 2018 to analyze the temporal and spatial changes in species composition, density, and biomass of zooplankton in Hongze Lake, as well as the seasonal changes in community diversity and dominant species. Canonical correspondence analysis was employed to explore the relationships between the temporal and spatial changes in zooplankton and the environmental factors of Hongze Lake. The results showed that the average annual density of zooplankton in Hongze Lake was 383.87 ind ·L, and the average annual biomass was 1.36 mg ·L. The community structure of zooplankton in Hongze Lake varied greatly across time and space. Community structure varied greatly in summer, and zooplankton density and biomass reached a maximum in autumn. The community structure of the zooplankton was the simplest in winter. Chengzi Bay and Lihewa Bay exhibited an abundance of many different zooplankton species with limited spatial differentiation, whereas the zooplankton in the overflow area comprised fewer species but exhibited greater spatial variation. In summer, water level and temperature are the dominant factors, whereas in autumn and winter, the dominant factors are water temperature, nutrients, and chlorophyll. Canonical correspondence analysis showed that the temporal and spatial changes in zooplankton community structure in Hongze Lake were mainly determined by water level, total phosphorus, water temperature, and total nitrogen content. Water level fluctuation has the greatest direct impact on zooplankton community structure, and water quality regulation has indirect impact.