中文摘要：

2011－2012年对三角湖浮游植物进行季节性调查，以了解浮游植物群落结构特征及其对水质的指示作用，为污染防治和生态修复提供依据。结果表明，在三角湖共采集浮游植物94种（变种），隶属于8门、25科、51属；其中，绿藻种类最多，约占总种数的59．6％，其次是硅藻、蓝藻和裸藻，分别占12．8％、11．7％和8．5％，其他门类种类较少。浮游植物细胞密度平均值为（102．32±59．89）×10^6个／L；其中，蓝藻密度最大，占浮游植物总丰度的86．69％，其次是绿藻和硅藻，分别占7．77％和4．91％，其他门类密度较低。浮游植物密度具有明显的季节变化规律，夏季的密度最大，秋季次之，冬季和春季较低。夏季和秋季蓝藻细胞密度占绝对优势，绿藻和硅藻次之，而冬季蓝藻密度下降，硅藻和绿藻占优势，春季蓝藻又重新占据优势。三角湖浮游植物Margalef丰富度指数、Shan-non-Weaver多样性指数和Pielou均匀度指数平均值分别为2．75、1．78和0．46。 Shannon-Weaver多样性指数和Pielou均匀度指数以冬季和春季较高，秋季最低，表明冬季和春季浮游植物群落结构相对复杂，而秋季的群落结构相对简单。综合水质生物学和水体理化指标评价结果，三角湖水体为中－富营养型。

英文摘要：

The community structure of phytoplankton in Sanjiao Lake was investigated and then used in the assess-ment of water quality.Phytoplankton diversity is widely used as a water quality indicator and the results of this stud-y provide a basis for managing eutrophication and support ecological restoration efforts.The shallow lakes in the Hanyang district of Wuhan are suffering from water quality deterioration and eutrophication.The “Six Lakes Con-nection Project” has been implemented to restore water quality and the project includes Sanjiao Lake.The social function of lakes in the project is changing from primarily aquacultural to ecological as restoration efforts improve the quality of these stressed urban waters.Sanjiao Lake is a typical small city lake with an area of 2.45 km2 , average depth of 0.88 m and maximum depth of 1.86 m.Samples were collected at ten sites in July （summer） and October （autumn） of 2011 and January （winter） and April （spring）, 2012.Water transparency, pH, conductivity, total nitrogen （ TN） and total phosphorus （ TP） were measured in July and October.Phytoplankton samples for qualita-tive analysis were collected with 25 μm plankton nets and fixed in 4%formaldehyde.1 L samples for quantitative analysis were collected 0.5 m below the surface and concentrated to 50ml after settling 48 h.Phytoplankton was i-dentified using a microscope.A total of 94 species, belonging to 51 genera, 25 families and 8 phyla, were collect-ed.The phytoplankton community was dominated by Chlorophyta, accounting for 59.6% of all species collected, followed by Bacillariophyta （12.8%）, Cyanophyta （11.7%） and Euglenophyta （8.5%）.The average cell den-sity of phytoplankton was （102.32 ±59.89） ×10^6 cells/L and dominated by Cyanophyta （86.69%）, followed by Chlorophyta （7.77%） and Bacillariophyta （4.91%）;abundance of other phyla were low （0.63%）.Cell density of phytoplankton displayed clear seasonal variation, densities are the hightst in summer, decline during au