城市人工湖泊浮游植物群落结构特征及其主要环境因子分析——以长沙梅溪湖为例

长沙梅溪湖为新兴城市人工湖泊,是国家级新区湘江新区的城市“海绵体”,其水环境与水生态状况是该区域高质量发展关注的重点,对维护湘江新区生态环境具有重要意义。为揭示梅溪湖水生态现状,分季度采集梅溪湖水样,分析浮游植物群落特征及其与环境因子的关系。结果显示梅溪湖浮游植物共有7门96种,其中以绿藻、硅藻和蓝藻种类数居多,占总种类数的86.46%,主要优势种为细小隐球藻（Aphanocapsa elacjista）、小环藻（Cyclotella sp.）、链状曲壳藻（Achnanthes catenata）和尖尾蓝隐藻（Chroomonas acuta）,优势种具有明显季节交替性。浮游植物年均密度为（23.97±9.95）×10^6 cells/L,各季度东部水域密度均高于西部水域;多样性指数评价结果表明梅溪湖水体处于中度污染和中-富营养状态,与水质评价结果基本一致。浮游植物与环境因子基于转化的冗余分析结果显示,水温、氧化还原电位、总氮和亚硝酸盐氮是影响梅溪湖浮游植物群落的主要驱动因子,控制总氮等营养盐的输入将是改善梅溪湖水质和营养状态的有效手段。

Structural Characteristics of Phytoplankton community and Analysis of Its main Environmental Factors in an Urban Artificial Lake, Lake Meixihu in Changsha City, China

As a new artificial lake, it is the "sponge body" of Xiangjiang New Area, Lake Meixihu in Changsha, China. Its water environment and ecology are the focus of high-quality development in Xiangjiang New Area. In order to reveal the ecological status of Lake Meixihu, the water samples of Lake Meixihu were collected quarterly, and the characteristics of phytoplankton community and their relationship with environmental factors were analyzed. A total 96 species of phytoplankton belonging to 7 phyla were found in Lake Meixihu. Chlorophyta, Bacillariophyta and Cyanophyta were the majority, accounting for 86.46% of the total species. The main dominant species were Aphanocapsa elacjista, Cyclotella sp., Achnanthes catenata, Chroomonas acutathe. The dominant species have obvious seasonal alternation. The average annual density of phytoplankton is (23.97±9.95)×106cells/L, and the density of the eastern waters is higher than that of the western in each season; the diversity index results show that Lake Meixihu is in moderate pollution and meso-eutrophic state, which is in line with the water quality. The results of the transformation-based redundancy analysis of phytoplankton and environmental factors showed that water temperature, redox potential, total nitrogen and nitrite nitrogen were the main driving factors affecting the phytoplankton community in Lake Meixihu. therefore, controlling the input of nutrients such as total nitrogen would be effective means to improve water quality of Lake Meixihu.