Abstract: To clarify the status of fishery resources and the relationships between fish community structure, biodiversity, and environmental factors, we conducted a consecutive five-year (2019-2023) field monitoring in the National Aquatic Germplasm Reserve of Cyprinus carpio and Leiocassis longirostris (Jintu Gorge, Huaihe River). We analyzed the spatiotemporal differentiations of fish community and identified the key driving environmental factors. The results showed that a total of 52 fish species were recorded, belonging to 5 orders, 11 families, and 38 genera. Cypriniformes was the dominant group, accounting for 67.38% of the total species, with obvious interannual variations in dominant species. The Shannon diversity index, Pielou evenness index, Margalef richness index, and Simpson dominance index showed significant temporal differences but spatial convergence, and the overall biodiversity was at a medium level in the Huaihe River Basin. The abundance-biomass comparison (ABC) curve analysis indicated that fish community was unstable from 2019 to 2020 and tended to stabilize during 2021-2023. Redundancy analysis (RDA) revealed that transparency, total nitrogen, and dissolved oxygen were the dominant environmental factors affecting fish community structure, followed by water temperature, ammonium nitrogen, and dissolved total phosphorus.

Key words: fish community structure, biodiversity, environmental factor, ecological regulation, Jintu Gorge of Huaihe River