Abstract: A one-year quarterly sampling survey in 2020 was conducted to explore the characteristics and driving factors of phytoplankton functional groups in the Jingtuxia Cyprinus carpio and Leiocassis longirostris national aquatic germplasm resources reserve of Huaihe River. Based on functional group classification, the temporal and spatial variations of phytoplankton community structure in the reserve were examined. Correlation analysis and redundancy analysis were used to analyze the data sets, and river ecological health index was used to explore water status in the reserve. The results showed that the phytoplankton in the reserve could be classified into 27 functional groups, and dominant functional groups were H1, J, P, Y, X2, D and MP. The seasonal variation followed a pattern of MP/P/Y (winter)-H1/J/P/Y (spring)-H1/P/X2 (summer)-D/X2 (autumn), with functional group P as the dominant functional group in spring, summer and winter. H1, P, and X2 were the common dominant functional groups in each region of the reserve, and D was the unique dominant functional group of Guohe River. Redundancy analysis results showed that chlorophyll a, permanganate index (COD_Mn), and pH were the main driving factors for the succession of phytoplankton dominant functional groups in the reserve. The ecological health index of the reserve ranged from 1.29 to 3.98, with an average of 3.07±0.72, and the water quality was generally good.

Key words: germplasm resources reserve, phytoplankton functional group, ecological health index, driving factor.