Seasonal Changes Drive Shifts in Bacterial Community Structure and Functional Composition in the Yellow River (Zhengzhou Section).

Urban rivers play a critical role in maintaining ecological functions and ensuring water security, yet their microbial communities remain vulnerable to seasonal and anthropogenic disturbances. In this study, we employed 16 S rRNA gene sequencing along with multivariate statistical methods to systematically investigate the characteristics of bacterial community composition and assembly mechanisms in river water and sediment of the Yellow River (Zhengzhou Section) across different seasons. Based on high-throughput sequencing and canonical correspondence analysis, bacterial community diversity in river water was found to be significantly higher during the wet season than in the dry season, primarily driven by water temperature, nutrient concentrations, and electrical conductivity. Conversely, bacterial community in sediment remained more stable, though pollution-tolerant bacteria became dominant in sediment with elevated pollutant concentrations during the dry season. Analyses of community assembly mechanisms showed that bacterial community in river water and sediment during wet season were mainly influenced by environmental selective pressures, including stochastic dispersal and physic-chemical barriers. Meanwhile, bacterial community in river water and sediment during dry season were more dominated by deterministic processes. Principal Coordinate Analysis and PERMANOVA further validated the significant impact of seasonal variation on bacterial community structure in both river water and sediment. These findings offer practical guidance for river ecosystem management and support the optimization of water use and environmental protection strategies in the Yellow River.