Aquatic community structure of the important habitat of Acipenser sinensis in the Yangtze River Estuary

The Yangtze River estuary is a critical habitat for the endangered Acipenser sinensis , supporting diverse aquatic communities vital for ecosystem functioning and the sturgeon’s survival. To assess the ecological conditions influencing A. sinensis ’s habitat, this study investigated the fish community structure, ecological indices, and seasonal variations in the estuary. Seasonal surveys from May to December 2024 identified 53 fish species across 12 orders, 22 families, and 44 genera, providing insights into the ecological dynamics of A. sinensis ’s habitat.Cyprinidae dominated the assemblage, representing 37.74% of species. Dominant species (based on IRI) such as Cynoglossus gracilis , Coilia nasus , and Lateolabrax japonicus are key indicators of habitat quality for A. sinensis . The community was predominantly sedentary (83.02%) and inhabited the mid-upper water column (50.94%). Carnivorous (50.94%) and omnivorous (33.96%) species dominated trophic guilds. Ecological indices indicated moderate diversity (Shannon-Weiner: 1.797–2.563; Simpson: 0.788-0.900; Margalef: 1.724–5.138; Pielou evenness: 0.526–0.864), essential for maintaining a balanced ecosystem for A. sinensis . Seasonal similarity analysis showed highest overlap between spring and summer (Bray-Curtis > 0.65), with comparable similarity between spring-autumn and autumn-winter. ABC curve analysis indicated minimal disturbance in spring (W = 0.041) but significant stress in autumn and winter (W=-0.068 to 0.276), correlating with seasonal hypoxia events. Summer displayed moderate disturbance (W = 0). These findings underscore anthropogenic pressures on habitat suitability for A. sinensis and highlight the need to prioritize the potential risk of seasonal environmental pressure on its survival.