Abstract: Seasonal and spatial variations of phytoplankton communities and its relationships with the main environmental factors in Shengjin Lake in February, April, July and November of 2014 were investigated. The results showed that in total of 210 species of phytoplankton were identified, which belonged to 91 genera of 8 phyla.Chlorophyta were most abundant,with 36 species of 89 genera(41.20%),and Bacillariophyta were the second,with 62 species of 26 genera(28.70%).The highest biomass recorded in summer(21.17±3.62 mg/L on average) and lowest recorded in winter(0.42±0.11 mg/L on average), the highest density was(4.57±0.29)×108cells/L in summer and lowest was(3.66±4.03)×105cells/L in winter. The seasonal succession of phytoplankton was consistent with PEG model in Shengjin Lake.Community structure analysis showed that Bacillariophyta was the second dominant population after Chlrophyta.The Shannon-Wiener index indicated phytoplankton diversity of 2.56-8.05(average 5.21). Redundancy analysis(RDA)revealed that the biomass of dominant functional was positively correlated with T,pH and SD.

Key words: Shengjin Lake;phytoplankton, environment factors, redundancy analysiss (RDA)