作者：Y. Wang, M. Liu, Q. Yan, C. Mao, W. Shu, S. A. Al-Farraj, et al.

The South-to-North Water Diversion Project (SNWDP) is a critical infrastructure initiative in China, with Lake Weishan serving as a key freshwater resource within this system. Water diversion significantly influences lake ecosystems, yet its impact on bacterioplankton communities, which play essential roles in biogeochemical cycles and water self-purification, remains poorly understood. In this study, we provide the first high-frequency, annual-scale analysis of bacterioplankton community dynamics in Lake Weishan, the largest freshwater impoundment lake in northern China and an important drinking water source. Over a 12-month period with fortnightly sampling using a metabarcoding approach, our findings revealed a clear and continuous annual succession in bacterioplankton communities, with community turnover playing a more dominant role than nestedness. Temporal variations in community composition were strongly correlated with key environmental factors, including water temperature, dissolved oxygen and electrical conductivity. The structure of bacterioplankton communities was predominantly shaped by stochastic processes. Co-occurrence network analysis indicated that mutualistic relationships were predominant within the community. Generalists exhibited broader ecological niches, stronger phylogenetic signals, and contributed more to maintaining alpha diversity compared to specialists. In contrast, specialists were more sensitive to environmental changes, exhibited greater temporal variability, and played a crucial role in sustaining co-occurrence network stability. Water diversion temporarily reduced bacterioplankton diversity and network stability while decreasing the influence of stochastic processes, particularly dispersal limitation. Despite these short-term effects, water diversion ultimately reshaped the bacterioplankton communities and contributed to their long-term stability. These results enhance our understanding of bacterioplankton dynamics by clarifying the roles of generalists and specialists, and by providing valuable insights into the impact of water diversion on microbial communities in impoundment lakes.

（来源：Journal of Hydrology 2025 Vol. 660  DOI: 10.1016/j.jhydrol.2025.133335）