Abstract: Dishui Lake is the largest artificial beach lake in China. From March 2009 to February 2010, a monthly investigation was conducted on the community feature of planktonic algae in the Lake. Canonical correspondence analysis (CCA) was applied to study the correlations between the algae species diversity and environmental factors by using software CANOCO 4.5, aimed to reveal the responses of the algae community to the ecological environment of the Lake. A total of 186 species and varieties of planktonic algae were detected, belonging to 92 genera of 8 phyla. Chlorophyta had the most species, followed by Cyanophyta and Bacillariophyta. Phorimidium tenus, Merismopedia tenuissima, M. glauca, Microcystis incerta, Oscillatoria tenuis, Cryptomonas erosa, Scenedesmus quadricauda, and Cocconeis placentula were the dominant species. The mean annual abundance and biomass of the planktonic algae were (4552.29±4591.33)×10⁴ cells·L^-1 and 8.15±6.63 mg·L-1, respectively. There was a significant difference (P＜0.01) in the standing crop of the algae between months, but no remarkable difference was detected among sampling stations. The diversity analysis showed that the species diversity was in good condition, and the CCA analysis indicated that the main factors affecting the community structure of the algae were water temperature and total nitrogen in the Lake.

Key words: Yangtze estuary, Collichthys lucidus, population parameters, resource situation.