Phytoplankton community structure and driving mechanism of its construction process in autumn in Zhelin Reservoir, Lake Poyang Basin

Abstract

研究环境过滤过程和空间扩散限制过程在构建水生浮游植物群落结构中的作用是了解这些因素如何驱动物种分布和影响群落结构的关键步骤.为了揭示鄱阳湖流域柘林水库浮游植物群落结构特征与环境因子的关系，以及明确环境因子和空间扩散限制性因子在浮游植物群落构建过程中的影响机制，于2020年10月，对柘林水库33个采样点的浮游植物和水质理化进行调查分析.共鉴定浮游植物7门122种，其中，以绿藻门种类最多，为34属62种，占总物种数的50.81%，硅藻门次之，为11属27种.柘林水库浮游植物优势种类主要是蓝藻门中的伪鱼腥藻属（Pseudoanabaena）、浮鞘丝藻属（Planktolyngbya）、小尖头藻属（Raphidiopsis）以及硅藻门中的针杆藻属（Synedra）.柘林水库浮游植物细胞丰度的变化范围为0.93×10⁶~172.12×10⁶ cells/L，平均值为95.42×10⁶ cells/L，生物量的变化范围为0.95~22.35 mg/L，平均值为9.35 mg/L.上游修河水域浮游植物生物多样性指数显著高于库心和库湾水域，库心与库湾水域之间浮游植物生物多样性指数差异性不明显.柘林水库上游修河水域浮游植物群落结构与库心和库湾水域存在明显分离，群落结构的差异性主要受水体透明度、电导率、氨氮和硝态氮的影响.变差分解结果显示，空间扩散限制性作用在驱动柘林水库浮游植物群落构建过程中占据主导地位.;Evaluation of the relative influences of environmental and spatial processes in structuring aquatic phytoplankton metacommunities is an essential step for understanding the species spatio-temporal distributions. To reveal the relationships between community structures of phytoplankton and the environment as well as clarify the driving mechanism of environmental factors and spatial diffusion limiting factors on phytoplankton community structure in Zhelin Reservoir, Lake Poyang Basin, the phytoplankton and water quality physicochemical characteristics of 33 sampling sites were investigated and analyzed in October 2020. A total of 122 species belong to 7 genera were identified, with 62 species in 34 genera were Chlorophyta, accounting for 50.81% of the total species, followed by Bacillariophyta with 27 species in 11 genera. The dominant species of phytoplankton in Zhelin Reservoir are Pseudoanabaena, Planktolyngbya and Raphidiopsis of Cyanophyta and Synedra of Bacillariophyta. The cell abundance of phytoplankton in the Zhelin Reservoir varied from 0.93×10⁶ to 172.12×10⁶ cells/L with an average of 95.42×10⁶ cells/L, and the biomass varied from 0.95 to 22.35 mg/L with an average of 9.35 mg/L. The phytoplankton biodiversity index in the upstream Xiuhe tributary area was significantly higher than that in the center of the reservoir area and the reservoir bay area, while no significant difference in the phytoplankton biodiversity index between the center of the reservoir area and the reservoir bay area was found. The phytoplankton community structure in the Xiuhe tributaries of Zhelin Reservoir was separated from that in the center reservoir and reservoir bay, and the differences were mainly affected by water transparency, electrical conductivity, ammonia nitrogen and nitrate nitrogen. The results of variation partitioning showed that the spatial diffusion limiting effect was dominant in driving the phytoplankton community structure in Zhelin Reservoir.