Analysis of Bacterial Community Composition in Sediments of the Mainstream and Tributaries in the Wanzhou Section of the Three Gorges Reservoir Area, China

River ecosystems are intricately connected to the biogeochemical processes mediated by sediment bacterial communities. The Three Gorges Reservoir, a critical freshwater resource, has seen limited research on bacterial community composition, particularly in comparative studies between its mainstream and tributaries. High-throughput sequencing was utilized to examine bacterial diversity and community structure in the sediments of the Wanzhou section. The analysis uncovered significant spatiotemporal heterogeneity and revealed similar community structures between the mainstream and tributaries, with Proteobacteria, Actinobacteria, and Bacteroidetes as the predominant phyla. Although no significant phylum-level differences were observed among the top five dominant species, their relative abundances showed notable variations. These differences are attributed to the reservoir's cyclical water storage and release, which alter nutrient concentrations and induce seasonal variations in bacterial communities. The intrinsic growth characteristics of microorganisms and their adaptive responses to environmental changes are identified as key factors influencing bacterial community differentiation. These insights enhance the understanding of bacterial dynamics in freshwater sediments and contribute to ecological assessments and environmental management in the Three Gorges Reservoir area.