Abstract: Based on the water quality monitoring data and phytoplankton survey data of 8 state-controlled monitoring points in Chaohu Lake in October 2019,May and October 2020, the diversity index of phytoplankton community structure in Chaohu Lake was analyzed, and the Pearson correlation analysis and redundancy analysis (RDA) of phytoplankton and environmental factors were carried out. The results showed that 41 genera and 61 species of phytoplankton were identified, among which the species of Chlorophyta were the most, followed by Cyanophyta and Bacillariophyta. Shannon-Wiener diversity index, Pielou evenness index and Margalef richness index in Chaohu Lake had the same change trend and gradually increased with time, indicating that the phytoplankton community structure in the water body was becoming more and more stable, and the water body gradually transited from medium pollution to light pollution. From the phytoplankton community structure and comprehensive trophic state index, the water body of Chaohu Lake was slightly eutrophic. Pearson correlation analysis and redundancy analysis showed that pH value, total nitrogen, transparency and dissolved oxygen were the main factors affecting the phytoplankton community structure in Chaohu Lake. These results could provide a reference for the environmental management of Chaohu Lake.

Key words: phytoplankton, community structure, diversity indicators, Pearson correlation analysis, redundancy analysis