Reservoirs enhance bacterial diversity but destabilize microbial co-occurrence network compared to natural lakes: A global meta-analysis

Globally, reservoirs have proliferated, becoming significant water bodies comparable to natural lakes. However, the functional equivalence between reservoirs and lakes in sustaining aquatic ecosystem services remains debated. As microbial communities are central to aquatic ecosystem functioning, they offer valuable insights into the impacts of human activities. To explore the ecological effects of anthropogenic disturbance on water bodies, this study focuses on microbes, which are drivers of ecological functions. The differences in bacterial structure, function, and main drivers between reservoirs and natural lakes were analyzed at a large spatial scale using a meta-analysis of 872 samples from 38 countries around the world. The results revealed that bacterial communities in reservoirs exhibited significantly higher richness and diversity but lower complexity and stability in microbial co-occurrence networks compared to lakes. Structural equation modeling indicated that bacterial community structure in reservoirs was significantly influenced by annual precipitation, evapotranspiration, and pH, whereas in lakes, it was primarily driven by water temperature and surface area. Notably, reservoirs showed a higher abundance of functional genes associated with human infectious and neurodegenerative diseases. Overall, these findings clarified the structural and functional distinctions between bacterial communities in reservoirs and lakes, providing new insights into the ecological impacts of anthropogenically disturbed water bodies.