三峡成库后支流回水区水华频繁发生，备受关切。基于2年的野外跟踪观测结果，利用典范对应（CCA）分析方法，建立了藻类生境要素同藻类集群演替的多元统计模型。研究发现，所建立的CCA模型有效且具有较高的显著性；水库季节性调蓄所形成的不同藻类生境条件是诱导集群出现演替的关键。在低水位运行下，藻类生境近似于天然河道，总悬浮颗粒物和流量变化对集群影响明显，水体扰动剧烈迫使耐受于不稳定水动力条件的藻种易于形成优势；而在高水位运行状态下，藻类生境接近深水湖泊，适宜于低温和具有运动功能的藻类将耐受于该生境状态并在集群中占优。

The frequencies occurring alga blooms in the backwater areas of tributaries of the Three Gorges Reservoir (TGR) have been a hot eco-environmental problem in this region. A gradient analysis based on the canonical correspondence analysis (CCA) was put forward to investigate the potential relationship between environmental factors and phytoplankton assemblages. It was found that the CCA model is effective and possesses a higher obviousness. Seasonal operation of the reservoir forms distinct existence conditions for phytoplankton assemblages. In summer season, the water body of surface is characterized by discharge change and many suspended particles, and it makes some phytoplanktons(e.g. syna etc.) form relative existence superiority. In the winter season, the rise of the water level in the TGR makes the habitat like deep lakes, the phytoplankton that prevails in the cold water and possesses moving function becomes the dominance species.