Abstract:

To fully understand the community structure of phytoplankton and its relationship with environmental factors, the species similarity index, evenness index and diversity index were used to analyze the community structure characteristics of phytoplankton in fall of Shihoudian Lake. The results show that 99 species of algae were detected, which belong to 6 phylums including Chlorophyta, Bacillariophyta, Cyanophyta, Euglenophyta, Cryptophyta and Pyrophyta, in the fall of the same year. The number of phytoplankton varies from 3.68×10⁷ to 8.22×10⁷cells/L. The biomass of phytoplankton ranges from 18.96 mg/L to 200.9 mg/L. The similarity index varies from 0.26 to 0.52, which is between slight and moderate similarities, with low similarity. The values of dominance analysis range from 0.07 to 0.31 in phytoplankton, which means that the dominance of phytoplankton is low, and there are various phytoplankton species. The results of diversity and evenness analysis are between 4.05-4.82 and 0.7-0.85, indicating that the community structure of phytoplankton is relatively stable in autumn. The water quality test results show that the value of TLI is between mild and moderate eutrophication. Correlation analysis shows that the environmental factors such as nitrogen and phosphorus affect the change of phytoplankton community structure. In autumn, the water body of Shihoudian Lake is moderately eutrophic, the community structure of phytoplankton is relatively stable, and the main nutrient elements of nitrogen and phosphorus have a greater impact on the changes of community structure of phytoplankton.

Key words: Shihoudian Lake, phytoplankton, community structure, characteristic, water quality assessment