Spatiotemporal Distributions of Bacterioplankton Communities in the Qiantang River (Hangzhou Section), China

The spatial and temporal distribution of bacterioplankton communities plays a vital role in understanding the ecological dynamics and health of aquatic ecosystems. In this study, we conducted a comprehensive investigation of the bacterioplankton communities in the Qiantang River (Hangzhou section). Water samples were collected quarterly from seven sites over a one-year period. Physical and chemical parameters, including dissolved oxygen (DO), water temperature (WT), chemical oxygen demand (COD), nitrite (NO2−), active phosphate (PO43−) and other indices were determined. In this study, the α diversity, β diversity and abundance differences of bacterial communities were investigated using 16S rRNA high-throughput sequencing analysis. The spatial and temporal distribution characteristics and main driving factors of the bacterioplankton community structure and diversity were discussed. The results showed that a total of 57 phyla were detected in the bacterioplankton community, among which Proteobacteria and Actinomycetes were the two dominant groups with the highest relative abundance. The results of PCoA based on Bray-Curtis distance showed that the sampling season had a slightly greater effect on the changes in bacterioplankton community structure in the Qiantang River. Mantel and partial Mantel test showed that environmental variables (Mantel r = 0.6739, P < 0.0001; partial Mantel r = 0.507, P = 0.0001) were more important than geographical distance (Mantel r = 0.5322, P < 0.001; partial Mantel r = 0.1563, P = 0.001). The distance attenuation model showed that there was significant distance attenuation in all four seasons, and the maximum limit of bacterial community diffusion was found in spring. RDA analysis showed that nine environmental factors, including COD, WT and DO, significantly affected community distribution (P < 0.05). This study provides valuable insights into the spatial and temporal distribution characteristics of bacterioplankton communities, shedding light on their ecological roles in the Qiantang River. The information obtained can guide future research on the interactions between bacterioplankton and their environment, enabling the development of effective conservation strategies and sustainable management practices for aquatic ecosystems.