2015~2020年洪泽湖浮游植物群落结构及其环境影响因子

洪泽湖是南水北调东线工程的重要调蓄湖泊，在气候调节、防洪防汛等方面起着重要的作用.为研究洪泽湖浮游植物群落结构演替及与环境因子的关系，了解“十年禁渔”前洪泽湖生态系统状况，于2015～2020年进行了逐月监测.研究期间，总氮(TN)年平均浓度从2017年之后呈显著下降趋势，总磷(TP)和化学需氧量(COD)总体呈下降趋势，水温无明显变化趋势，水深和透明度从2015～2018年上升，之后显著下降.调查期间共鉴定有浮游植物8门102属310种，浮游植物优势门类主要包括绿藻门和硅藻门，其次为蓝藻门和甲藻门.主要优势属为栅藻(Scenedesmus)、直链藻(Aulacoseira)、隐藻(Cryptomonas)、小环藻(Cyclotella)、四角藻(Tetraedron)、微囊藻(Microcystis)和长孢藻(Dolichospermum).非度量多维尺度分析方法(NMDS)表明，洪泽湖浮游植物群落结构组成在不同年份、不同季节和不同采样区域有显著差异，其变化主要是浮游植物的优势种属间再分配.NMDS分析结果显示，洪泽湖浮游植物群落结构变化与水温、 TN、 TP、水深和透明度等因素有关...

Community Structure of Phytoplankton and Environmental Impact Factors in Lake Hongze from 2015 to 2020

Lake Hongze is an essential storage lake for the "Eastern Route of the South-North Water Diversion Project" and plays an important role in climate adjustment and flood prevention and control. To study the structural evolution of phytoplankton communities in Lake Hongze and their relationship with environmental factors and to understand the status of the ecosystem of Lake Hongze before the "ten-year fishing ban," monthly monitoring was carried out from 2015 to 2020. During the study period, total nitrogen showed a significant downward trend starting in 2017, the total phosphorus and chemical oxygen demand declined slightly, the water temperature had no obvious change trend, and the water depth and transparency increased from 2015 to 2018 and then declined significantly. A total of 102 genera of phytoplankton in eight phyla were identified, with a total of 310 species. The dominant phytoplankton phyla mainly included Chlorophyta and Bacillariophyta, followed by Cyanophyta and Pyrrophyta. The dominant genera were Scenedesmus, Aulacoseira, Cryptomonas, Cyclotella, Tetraedron, Microcystis, and Dolichospermum. The results of non-metric multidimensional scaling (NMDS) showed that the structural composition of the phytoplankton community differed significantly among years, seasons, and sampling areas, mainly due to the redistribution among dominant genera. NMDS analysis also indicated that variation in the phytoplankton community in Lake Hongze was mainly related to water temperature, total nitrogen, total phosphorus, water depth, and transparency. Total nitrogen, water depth, and phytoplankton community structure were significantly correlated with interannual succession, whereas water temperature, total nitrogen, and phytoplankton seasonal succession were also significantly correlated. Combined with the measures taken by the management department in recent years, the changes in the structure of the phytoplankton community may be related to the removal of the fence and other management and restoration measures in Lake Hongze.