Author(s): Jiajian Qiu; Saiyu Yuan; Hongwu Tang
Linked Author(s): Jiajian Qiu, Hongwu Tang, Saiyu Yuan
Keywords: Large river-lake system Fish connectivity Ecological management Hydrological processes Extreme drought
Abstract: Climate change and anthropogenic stressors modify hydrological rhythms of river-lake systems, profoundly impacting their environment and aquatic communities. Adopting a holistic approach that considers the ecological connectivity of river-lake systems and its response to hydrological rhythms is more beneficial to enhance ecological resilience, yet such approaches remain underdeveloped. This study conducted year-round field surveys of fish assemblages and physical habitats of the Yangtze-Poyang system, the largest river and largest freshwater lake in China. The results showed extreme drought led to substantial shifts in fish density distribution, species diversity, and interaction of fish assemblage between the river and lake. Decreased hydrological connectivity caused fish aggregating in a few river segments, with densities spiking up to six times that of flood season. Additionally, more than 20 species disappeared, greatly weakening river-lake fish connectivity. Model simulation further identified potential causes of changes in fish connectivity and provided insights of ecosystem management focused on hydrological rhythms. The findings indicated that reduced suitable habitats accounted for the decline in fish connectivity, with extreme drought exerting delayed and lasting negative impact on fish community even after it ended. A moderate increase in the flow discharge during the early dry season could considerably improve habitat suitability for various fish species, whereas belated regulation was no longer effective. This research supports a new theoretical framework and provides a scientific reference for more timely and efficient ecological management in river-lake settings.
Year: 2025