Spatiotemporal dynamics of the bacterioplankton community in a subtropical estuary

Using high-throughput sequencing of 16S rRNA gene from surface water, we investigated biogeographical patterns, community assembly processes, and co-occurrence network of bacterial communities along the Changjiang River Estuary across different seasons. Significant spatial variations in bacterioplankton composition between the Inner and the Outer zone overwhelms seasonal changes in bacterial community structure. However, co-occurrence network structure, showed greater discrepancies across seasons compared to spatial scales, with summer exhibiting less complexity than other seasons. Bacterial communities were dominantly governed by stochastic assembly processes, in which drift explaining 53.25% of the community variation. This dominance of stochastic processes was proposed to be further reinforced by higher water discharge from the Changjiang River, coupled with increased dispersal rates of bacteria and enhanced water connectivity and homogeneity.