Exploring bacteria communities in lakes and reservoirs: a global perspective

Understanding bacterial biogeography is crucial for managing freshwater ecosystems. However, global comparisons of bacterial communities in lakes and reservoirs remain limited. This study synthesized bacterial community data from 247 water and 131 sediment samples across diverse geographic regions through a global literature review. Bacterial diversity and community structure were compared between water and sediment, aiming to identify key environmental drivers and biogeographical patterns. The present results show that sediment samples generally exhibit higher and more variable bacterial diversity than water samples. Generalized additive models revealed that total phosphate is negatively correlated with the diversity of bacterial communities in water. In sediments, the regulatory effect of total nitrogen on community richness is particularly significant. Structural Equation Modeling showed that latitude gradients and nutrient concentrations jointly drive geographical variation in bacterial α diversity. By constructing a global standardized database, the indicative role of core groups such as the Proteobacteria phylum in lakes and reservoirs with different nutrient levels has been established, while Cyanobacteria and Actinobacteria are enriched in eutrophic environments. The results of Random Forest analysis showed that temperature was the most important environmental factor affecting bacterial community structure in water, while nitrate nitrogen showed the highest importance in sediment. Network analyses further showed that bacterial communities in water formed more complex and interconnected networks than those in sediments. These findings reveal the global distribution patterns of bacterial communities in water and sediment habitats, offering new insights for ecosystem monitoring and microbial-based water quality management, on a global scale.