洞庭湖区南汉垸水体浮游植物群落结构特征及其影响因素

环境要素的变化对浮游植物的群落结构和功能具有重要影响.为揭示洞庭湖南汉垸湖区浮游植物群落结构特征及其影响因素，分别于2017年11月（关泵封水期）和2018年6月（开泵放水期）在洞庭湖区典型堤垸——南汉垸进行了采样调查，并对调查区域内的浮游植物及主要水环境因子进行了系统监测和分析.结果表明:①调查期间共检出浮游植物8门62属，主要隶属于绿藻门（Chlorophyta）、硅藻门（Bacillariophyta）和蓝藻门（Cyanophyta），浮游植物分布表现出较为显著的时间差异性，11月浮游植物的丰度为8.34×106~3.02×108 L-1，6月为1.13×106~2.04×107 L-1.②Shannon-Wiener多样性指数（H'）介于1.10~3.24之间，Margalef丰富度指数（d）介于1.42~6.40之间，Pielou均匀度指数（J）介于0.48~0.87之间，多样性评价表明，南汉垸整体上介于轻污染与β-中污染之间，局部采样点为α-中污染.③PCA（主成分分析）结果表明，ρ（TN）、ρ（TP）和ρ（NH₄+-N）为南汉垸水体的主要污染因子.④RDA（冗余分析）结果表明，南汉垸浮游植物群落结构分布与pH、ρ（NH₄+-N）及ρ（TN）呈正相关，与WT（水温）呈负相关.研究显示，南汉垸水体介于轻污染与β-中污染之间，营养状态及浮游植物群落结构在时间上差异较大. 

Phytoplankton Community Structure and Its Influencing Factors in Nanhan Polder Area of Dongting Lake

The variation of environmental factors has a significant impact on the community structure and function of phytoplankton. In order to reveal the characteristics of phytoplankton community structure and its influencing factors in water bodies of Nanhan Polder in Dongting Lake Area, samples were collected in Dongting Lake was collected for analysis in November 2017 (period of pump closed) and June 2018 (period of pump open). Meanwhile, the phytoplankton and the main water environmental factors were systematically monitored and analyzed in the study area. The results showed:(1) 8 phyla and 62 genera of phytoplankton were detected during the survey, whereas Chlorophyta, Bacillariophyta and Cyanophyta were the dominant species. The distribution of phytoplankton showed significant temporal differences, with the abundance of 8.34×106-3.02×108 L-1 in November and 1.13×106-2.04×107 L-1 in June. (2) The Shannon-Wiener diversity index (H') ranged from 1.10 to 3.24, the Margalef richness index (d) ranged from 1.42 to 6.40, and the Pielou evenness index (J) ranged from 0.48 to 0.87. Through the diversity assessment, the pollution levels in the water bodies of Nanhan Polder were generally at mild and β-medium level and occasionally at α-medium level. (3) PCA (Principal Component Analysis) analysis regarded ρ(TN), ρ(TP) and ρ(NH₄+-N) as the main pollution factors in the water bodies of Nanhan Polder. (4) RDA (redundancy analysis) analysis indicated that the distribution of the phytoplankton community structure was positively correlated with pH, ρ(NH₄+-N) and ρ(TN), and negatively correlated with WT (water temperature). Overall, results show that the water quality of Nanhan Polder was between mild and β-medium pollution, and trophical status and phytoplankton community structure varied greatly with time. The research results can provide reference for water pollution control and ecological restoration in Dongting Lake Area.