长江三口-西洞庭湖环境因子对浮游植物群落组成的影响

为了解长江三口及西洞庭湖浮游植物群落结构特征及主要环境影响因子,于2016年11月、2017年3月及8月对长江三口及西洞庭湖18个断面进行了浮游植物的调查,共检出6门72种,群落结构分析结果表明：浮游植物密度方面,在11月份最低,8月份最高,变化范围为1.32~275×10⁴cells/L,平均密度为32.75×10⁴cells/L,其中,长江三口平均密度为35.39×10⁴cells/L,西洞庭湖为25.88×10⁴cells/L;优势类群方面,长江三口以硅藻门的尖针杆藻（Synedra acus）、瞳孔舟形藻（Navicula pupula）、双头辐节藻（Stauroneis smithii Grun）为主,西洞庭湖则以蓝藻门的小席藻（Phormidium tenue）,绿藻门的小球藻（Chlorella vulgaris）、四尾栅藻（Scenedesmus quadricauda）为主;多样性方面,长江三口Shannon-Wienner指数及Margalef指数分别为1.31和1.01,西洞庭湖Shannon-Wienner指数及Margalef指数分别为1.40和1.10,通过对浮游植物和水环境因子数据进行CCA分析可知,水温（WT）、总氮（TN）、总磷（TP）是影响长江三口浮游植物分布的主要因素,而WT、pH值是影响西洞庭湖区浮游植物分布的主要因素.

Effects of environmental factors on the composition of phytoplankton community in Sankou of the Yangtze River and the Western Dongting Lake

To evaluate characteristics of phytoplankton community structure and main environmental impact factors in the "Sankou" of Yangtze River and the Western Dongting Lake, phytoplankton from 18 sampling sites which distributed in "Sankou" and Western Dongting Lake were investigated in November 2016, March and August 2017. 72 species of six phyla was detected, and the phytoplankton density was in a range from 1.32 to 275×10⁴cells/L with the lowest in November and the highest in August, which the average density was 32.75×10⁴cells/L. The average density in Sankou of Yangtze River and the West Dongting Lake were 35.39×10⁴cells/L and 25.88×10⁴cells/L, respectively. In terms of dominant groups, Synedra acus, Navicula pupula and Stauroneis smithii Grun dominated in "Sankou" of the Yangtze River, and the West Dongting Lake is dominated by the Phormidium tenue of Cyanophyta, Chlorella, vulgaris and Scenedesmus quadricauda of Chlorophyta. In terms of diversity, the Shannon-Wienner index and the Margalef index of the "Sankou" of the Yangtze River were 1.31 and 1.01, while that were 1.40 and 1.10 in the West Dongting Lake, respectively. The CCA analysis of phytoplankton and water environmental factors indicated that, water temperature (WT), total nitrogen (TN) and total phosphorus (TP) were the main factors affecting the distribution of phytoplankton in "Sankou" of Yangtze River, while WT and pH were main factors of distribution phytoplankton in the Western Dongting Lake.