中文摘要：

研究千岛湖浮游植物群落结构特征及其与主要环境因子的关联性,为了解千岛湖水环境变动规律及水环境的保护与管理提供依据。沿水流方向在水库上中下游依次设置5个采样点,2010年对千岛湖浮游植物群落开展了周年调查。共鉴定出浮游植物8门223种,其物种数、密度和生物量均主要由硅藻、蓝藻和绿藻组成。不同浮游植物门类物种数、密度和生物量组成比例站点间无显著差异;群落总密度和生物量站点间无显著差异,但有显著的季节变化,它们的垂直分布均呈现先增加后下降的趋势,在4-8 m水层具有最大值。Shannon多样性和Pielou均匀度指数在空间和季节间均无显著差异,但Margalef丰富度指数存在显著的季节和空间差异。聚类分析（CA）和多维尺度分析（MDS）表明,藻类物种组成在站点间无显著差异,但具有显著的季节变化,即分化为春季、冬季和夏秋季3种群落类型,春季群落主要特征种为颗粒直链藻及其狭窄变种和尖尾蓝隐藻,冬季为水华鱼腥藻、颗粒直链藻狭窄变种和脆杆藻,夏秋群落为网状空星藻、水华鱼腥藻和梅尼小环藻。相关性分析表明,浮游植物密度和生物量与水温、pH值、CODMn和Chl-a显著正相关,与SD和DO显著负相关;生物量与Si O2-3-Si显著正相关。典范对应分析（CCA）显示,水温、DO和NO-3-N及pH值是影响浮游植物时空分布的主要因子。

英文摘要：

Phytoplankton is a good indicator of changes in the water environment of rivers,lakes and reservoirs. In this study,we characterized the phytoplankton community structure and its relationship to environmental factors in Qiandao Lake,based on monthly sampling in 2010 and multivariate statistical analysis. The study will help to understand of the changes in water quality in Qiandao Lake and provide data to support conservation and management of aquatic resources. Qiandao Lake,originally named Xin＇anjiang Reservoir is in the mountain region of western of Zhejiang Province,near the border of Anhui Province,and is an important water resource of Qiantang River. Five sampling sites were located on Qiandao Lake： S1,in the river section of upper Qiandao Lake; S3 and S4,in the transition zone between riverine and open water sections; S8 and S9,in the open lake area of lower Qiandao Lake.From January to December of 2010,composite water samples from different layers were collected monthly at each sampling site for phytoplankton identification,counting,density and biomass calculation. Environmental parameters were measured in situ and water samples collected for lab,including water temperature（ T）,dissolved oxygen（ DO）,pH,diaphaneity（ SD）,total nitrogen（ TN）,total phosphorus（ TP）,nitrate nitrogen（ NO3-N）,nitrite nitrogen（ NO2-N）,total ammonia nitrogen（ TAN）,permanganate Index（ CODMn）,Chl-a and silicates（ Si O2-3-Si）. A total of 223 species belonging to 8 phyla were identified,with absolute dominance by Chlorophyta,Bacillariophyta and Cyanophyta in terms of species number,density and biomass. Species number,density and biomass did not differ significantly among sampling stations. Total density and biomass of the phytoplankton community was also similar among the five stations,but varied significantly with season. Vertical distribution of phytoplankton density and biomass peaked at depths of 4-8 m and then decreased. No significant spatial and seasonal variations were observed in Shan