洪泽湖浮游动物时空分布特征及其驱动因素

洪泽湖是我国第四大淡水湖，承担着周边的工农业用水以及为人类提供渔业资源等重要功能.研究洪泽湖浮游动物群落结构变化可为洪泽湖生态环境的科学管理提供理论依据.通过2017年3月至2018年2月的逐月调查数据，结合洪泽湖浮游动物的种类组成、密度和生物量的时空变化，以及群落多样性和优势种的季节变化特征，并运用典范对应分析等方法探讨了洪泽湖浮游动物的时空变化与环境因子的相互关系.群落结构分析表明，洪泽湖浮游动物年均密度为383.87 ind·L^-1，年均生物量为1.36 mg·L^-1.洪泽湖浮游动物群落结构时空变化较大，时间上夏季浮游动物群落结构波动较大，秋季浮游动物密度与生物量均达到最大值，冬季浮游动物群落结构最为简单；空间上成子湖和溧河洼浮游动物较为丰富，差异较小，过水区浮游动物较少且变化较大.典范对应分析表明，洪泽湖浮游动物群落结构的时空变化与水位、总磷、水温和总氮等因素显著相关.不同时间浮游动物群落结构变化的主导因素不同，夏季主导因素是水位与水温；秋冬季主导因素是水温、营养盐及叶绿素等.不同湖区点位集中程度不同，过水区分布的更为分散，浮游动物群落结构差异较大，成子湖和溧河洼分布的相对集中，浮游动物群落结构差异较小.水位波动对浮游动物群落结构的变化影响最大，表现在水位波动会直接影响浮游动物群落结构，同时也会通过影响水质而间接影响浮游动物群落结构.

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^-1, and the average annual biomass was 1.36 mg ·L^-1. 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.