为探究南水北调中线水源区丹江口水库浮游植物群落结构变化及其生物多样性，于 2014—2015 年对丹江 口水库进行为期 1 年的调查和分析。发现浮游植物共 8 门 76 属 101 种，其中，绿藻门、蓝藻门及硅藻门占总种数 90.10%，绿藻门种类数最多（45 种），其次是蓝藻门（26 种）和硅藻门（20 种）。浮游植物群落结构随季节变化有所 不同：夏秋季节生物量明显高于冬春季节；优势种在冬季以颗粒直链藻、颗粒直链藻极狭变种、铜绿微囊藻和小 环藻为主，春季以球衣藻、薄甲藻属及小环藻为主，夏季以简单颤藻、单胞衣藻原变种和球衣藻为主，秋季以类颤 藻鱼腥藻、简单颤藻、球衣藻和小环藻为主。应用 Shannon-Wiener 多样性指数 H′、Pielou 均匀度指数 J′、Margalef 丰富度指数 Dm评价水质结果表明：丹江口水库夏秋季水体营养化程度更高。典型对应分析表明：水温、透明度、 总氮、总磷等是影响浮游植物群落结构的主要环境因子，夏秋季受温度影响蓝藻、绿藻数量逐渐增多，一定程度 上增加了受水区生态变化风险。本研究可为南水北调中线水源区丹江口水库生态环境变化及生物迁移风险提供 数据支持。

Phytoplankton can respond quickly to environmental changes caused by water quality parameters, climate and hydrodynamic conditions, and is often used to monitor water quality pollution. Its species composition, the succession of dominant species, and biodiversity can reflect the water ecological environment in the reservoir area. Since the middle route of the South-to-North Water Transfer Project was officially put into operation in 2014, due to the increase of the reservoir capacity area after the dam was raised, many slow flow areas were generated along the bank lines, which caused easily growing algae. Long-term water transfer may change the phytoplankton community structure of Danjiangkou Reservoir, affect the ecological environment around the water source area and cause water quality problems. Therefore, it is particularly important to understand the spatial and temporal distribution characteristics of the phytoplankton community structure in the Danjiangkou Reservoir and evaluate the potential risk of eutrophication. A portable water quality detector (HACH SL1000) was used to measure pH, temperature, conductivity (Cond), ammonia nitrogen (NH4 +-N),nitrite nitrogen (NO2--N), and nitrate nitrogen (NO3--N). Total phosphorus (TP) was measured by ammonium molybdate spectrophotometry GB 11893-1989, total nitrogen (TN) was measured by alkaline potassium persulfate ultraviolet spectrophotometry GB 11892-1989, and transparency (SD) was measured by Plug plate. A 25# plankton net (64 μm) was used to do "∞" zigzagging for 3-5 minutes at a depth of 0.5 m to collect qualitative samples of phytoplankton. A plexiglass water collector was used to collect quantitative samples of phytoplankton at a depth of 0.5 m. The number of phytoplankton was calculated by the eyepiece field method, the biological volume was calculated by morphological characteristics and measured by a microscope. The biomass was calculated by the volume conversion method. Dominance Y, Margalef richness index, Pielou evenness index, and Shannon-Wiener diversity index were selected to calculate phytoplankton community indicators. Typical correspondence analysis (CCA) between phytoplankton and environmental factors was performed using Canoco 4.5 software.