Characteristics and environmental driving mechanisms of bacterial communities in the Bohai Sea

The Bohai Sea, a semi-enclosed marginal sea, hosts a diverse array of bacterial communities that play pivotal roles in marine biogeochemical cycles. However, understanding of bacterial communities remains fragmented in the Bohai Sea, with unclear links between environmental factors and key species, and limited insights into the roles of environment and space in shaping the bacterial communities. In this study, we compiled a series of data, and investigated how spatial and environmental factors influence the region's distribution, assembly, and function of bacterial communities using high-throughput sequencing and statistical analyses. The results revealed that the bacterial communities in the Bohai Sea exhibited a high heterogeneity of spatial and environmental factors. Major drivers of community assembly included geographic location, nutrient availability (NO₂-N, NO₃-N, and NH₄-N), temperature, and dissolved oxygen. Additionally, we found that the bacterial community structure in the nearshore waters of the Bohai Sea was distinctly different from that in the distant seas. Furthermore, we identified key bacterial species, including Marinimicrobia, Proteobacteria, Lentisphaerae, and Cyanobacteria that significantly contributed to community structure and function by random forest analysis. Notably, the abundance of Cyanobacteria was strongly correlated with environmental factors (NO₂-N, NO₃-N, and NH₄-N), suggesting their potential as bioindicators of environmental change in marine ecosystems. More importantly, deterministic processes in the assembly of bacterial communities played a greater role than stochastic processes in highly polluted regions (BS3). The results of this research enhanced our understanding of the ecological processes governing bacterial community dynamics and provided valuable insights for monitoring and management marine ecosystem.