内蒙古高原咸水湖岱海浮游植物群落时空分布特征及驱动因子OA

Phytoplankton,as the primary producers in lake ecosystems,influence material cycling and energy flow within water bodies.Their community structure and dynamic changes directly reflect the nutrient status and ecological health of the water body.To comprehensively understand phytoplankton variations and influencing factors in tailwater lakes of northern arid-cold regions,the representative Lake Daihai was selected as the study site.Water and sediment samples were collected across all four seasons in 2024 to systematically analyze phytoplankton community structure and its response to environmental factors.Results indicate that during the study period,water body total nitrogen(TN)and total phosphorus(TP)concentrations exceeded Grade V and Grade Ⅳwater standards,respectively,while sediment TN and TP contents surpassed the national sediment average.A total of 95 phyto-plankton species belonging to 8 phyla were identified,dominated by Chlorophyta,Cyanobacteria,and Bacillariophyta.Phytoplank-ton cell density,biomass,and Chl.a concentration peaked in winter.Twelve dominant species across 5 phyla were identified,pri-marily from Chlorophyta and Bacillariophyta,with Microcystis and Chroomonas serving as key dominant genera throughout the year.Results from Shannon diversity index,Pielou evenness index,Margalef richness index,and Simpson dominance index indicated higher phytoplankton community diversity and greater ecosystem stability in spring and summer compared to autumn and winter.Phytoplankton communities in Lake Daihai exhibited low spatial heterogeneity,suggesting that diversity and richness are primarily influenced by seasonal variations.Statistical analysis indicates that water temperature,pH,dissolved oxygen,TN,and dissolved inorganic phosphorus are key factors influencing phytoplankton community structure.Multi-year surveys reveal that the dominant phytoplankton species in Lake Daihai have shifted from Bacillariophyta and Chlorophyta to Cyanobacteria and Cryptophyta.This study uncovers the key mechanisms driving seasonal succession in phytoplankton communities of northern cold-arid lakes,providing a scientific basis for ecological management and conservation of Lake Daihai.