Study on the spatial distribution characteristics of microbial communities and their environmental driving factors in Bing’an Reservoir after initial impoundment

After the initial impoundment of Bing’an Reservoir on the Chishui River, alterations are likely to occur in the structural composition and diversity of microbial communities. To unravel the microbial community diversity, community abundance, phylum composition, and spatial distribution characteristics within the reservoir, this study collected water samples from the surface, shallow, and middle layers. High-throughput sequencing technology targeting the bacterial 16S rRNA-encoding gene was employed to analyze the composition and diversity of microbial communities at different depths. The results demonstrated that the planktonic bacterial community in the reservoir was predominantly composed of prokaryotes (bacteria and archaea), with high microbial diversity and abundance. Among these, Pseudomonas and Massilia were the relatively dominant genera. The community structure and diversity of microorganisms were closely associated with water quality conditions. Results of variation partitioning analysis revealed that the impact of physicochemical factors on microbial community structure was significantly greater than that of geographical factors. Canonical correspondence analysis indicated that total phosphorus (TP), temperature (T), chemical oxygen demand (COD), pH, chlorophyll-a (Chl-a), ammonium nitrogen (NH 4 + -N), dissolved oxygen (DO), where the major driving forces shaping the microbial community structure. This study contributes to a better understanding of the ecosystem functions of Bing’an Reservoir, especially during the initial impoundment stage, and provides a scientific reference for the improvement and management of the water environment in the reservoir area.