Microbial Community Assembly and Co-Occurrence Relationship in the Sediments of the River-Dominated Estuary and the Adjacent Shelf

Abstract

Estuaries are essential transition zones between riverine and marine ecosystems, supporting complex biogeochemical cycles. In the estuarine ecosystem, the microbial community plays a vital role in controlling biogeochemical cycles. However, there is currently limited comprehensive study on the deterministic and stochastic processes that drive the microbial community assembly in this ecosystem. In this study, we systematically investigated the co-occurrence relationship and microbial community assembly in the sediments of three transects in a large river-dominated estuary and its adjacent shelf in the northern South China Sea. The microbial co-occurrence networks, variation partitioning analysis, null model, neutral community model, and the Mantel test were used in this work. Results indicated that microbial communities in the estuary transect had more linkages than nearby shelf transects. In all three transects, stochastic processes were more important to microbial community assembly than deterministic processes. The hydrodynamic disturbance was believed to be the key regulator of the differences in microbial community assembly between the estuary and the neighboring shelf. Our research adds to our knowledge of microbial community assembly in the estuary and adjacent shelves.

Keywords: Estuaries, Microbial community, Null model, Stochastic processes, Community assembly