Abstract: Phytoplankton community structure of Lake Nanyi in Anhui province was studied from March to August, 2015. The results showed that one hundred and twenty species belonging to seven phyla and sixty genera were identified in Lake Nanyi, among which Chlorophyta (69 species) ranked the first, followed by Bacillariophyta (16 species), Cyanobacteria (14 species) and Euglenophyte (13 species). The total density and total biomass (Mean±standard deviation) of phytoplankton in Lake Nanyi were (90.53±58.48)×105cells/L and (4.21±2.48) mg/L, respectively. Phytoplankton density in Lake Nanyi showed an increasing trend during the study period, whereas the pattern of phytoplankton biomass was decreased firsly and then increase. In spring, the phytoplankton biomass was dominated by Phacus and Cyclotella, whereas it was replaced by Euglena, Pediastrum and Microcystis in summer. In Lake Nanyi, the rapid changes of water temperature and nutrients may be the important reasons for the seasonal variation of phytoplankton community structure in spring and summer.Lake Nanyi; phytoplankton; community structure; environmental factors

Key words: Lake Nanyi, phytoplankton, community structure, environmental factors