呼伦湖及周边水域浮游植物群落构建机制与关键驱动因子OA

Lake ecosystems in cold and arid regions are sensitive to climate change and human disturbances,and the dynamics of their phytoplankton communities serve as important indicators characterizing changes in the aquatic ecological environment.Lake Hulun,a typical shallow lake in the arid and semi-arid regions of northern China,has exhibited eutrophication characteristics fol-lowing the implementation of the"River Diversion to Lake"project.Therefore,exploring the assembly mechanism of its phyto-plankton community and the key environmental driving factors is of great significance for lake ecological restoration and algal bloom prevention and control.In the spring and summer periods of 2024 and 2025,a systematic ecological investigation was conducted at 25 sites in the main lake area and main inflow waters of Lake Hulun,aiming to analyze the seasonal succession patterns,taxonomic beta diversity characteristics of phytoplankton communities,and their coupling relationships with environmental factors.The results indicated that the phytoplankton community structure in Lake Hulun displayed significant seasonal succession.The dominant groups in spring showed significant inter-annual succession,changing from the common dominant groups of Cyanobacteria and Chlorophyta in 2024 to Chlorophyta and Bacillariophyta in 2025;in summer,the absolute dominant group was Cyanobacteria in both years.Microcystis aeruginosa and Anabaena circinalis became the dominant species.The annual average phytoplankton cell a-bundance was 2.42×105 cells/L,and the seasonal distribution showed that the density in summer(2.95×105-3.20×105 cells/L)was significantly higher than that in spring(1.68×105-1.76×105 cells/L).Although species richness was relatively higher in summer,the Shannon-Wiener diversity index of the community was significantly lower than that in spring.Canonical correspon-dence analysis showed that the spring community was mainly affected by total phosphorus,turbidity,and dissolved oxygen,while the summer community was mainly driven by factors such as water temperature,total nitrogen,five-day biochemical oxygen de-mand,and chlorophyll-a.Decomposition of taxonomic beta diversity revealed that the taxonomic beta diversity between seasons and years was dominated by the turnover component,indicating that species replacement is the core process in the assembly of the phy-toplankton community in Lake Hulun,reflecting strong environmental filtering effects and habitat heterogeneity.This study demon-strates that environmental filtering is the core driving force affecting the seasonal dynamics of the phytoplankton community in Lake Hulun from two dimensions:species composition and community assembly mechanism.The research results not only identified the key regulatory factors in the eutrophication process of Lake Hulun but also provided an important scientific basis for the aquatic eco-logical health assessment,cyanobacterial bloom early warning,and ecological restoration practices of this lake and similar cold and arid lakes in northern China.