Environmental drivers of the functional structure of fish communities in the Pearl River Estuary

Estuarine biodiversity and ecosystem functioning are strongly impacted by environmental changes, including changes in salinity, temperature, transparency, dissolved oxygen, and nutritional status. Many previous studies on fish community biodiversity examined species richness and composition but failed to consider functional traits and diversity. In this study, we applied a functional approach to explore how environmental factors affect the functional diversities and traits of fish communities in the Pearl River Estuary (PRE). During 24 scientific surveys, a total of 15 387 individuals were sampled, belonging to 112 species, 95 genera, and 56 families, with freshwater species being the more abundant category. Seasonal changes significantly affected the functional dispersion and quadratic entropy Q of the fish community. Temperature and NO3 were critical environmental factors that determined the functional diversity of the fish community. Structural and functional composition varied significantly among seasons. Species composition was more dissimilar than functional composition among the different river mouths. Overall, we assessed the functional diversity of the fish community and revealed that environmental factors, such as turbidity, total nitrogen, and NO3, affect functional traits and diversity of the fish community in the PRE.