Polychaete Bioturbation Alters the Taxonomic Structure, Co-occurrence Network, and Functional Groups of Bacterial Communities in the Intertidal Flat.

Polychaetes are important benthic macrofauna that lives in sediments, usually in intertidal flats with high organic content and high sulfide. It has been suggested that polychaete bioturbation could perform environmental remediation. During the process, the microbial community plays important roles. Here, we used high-throughput sequencing technology to study the bioturbation effects on the bacterial community in the polychaete (Perinereis aibuhitensis) burrows at different tidal positions in intertidal flat. The results showed that the bacterial communities were dramatically influenced by the polychaete bioturbation. The ACE, Chao, and Shannon indices of the polychaete burrows increased in summer. Dominant phyla in the polychaete burrows were Proteobacteria, Campilobacterota, Desulfobacterota, Chloroflexi, and Bacteroidota, and the dominant bacterial families were Sulfurvaceae, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, Desulfobulbaceae, and Sulfurimonadaceae. Results of linear discriminant analysis effect size (LEfSe) showed that groups that include organic matter degraders, such as Bacteroidota, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, and groups that include sulfur oxidizers, such as Campilobacterota, Sulfurovaceae, Rhodobacteraceae, Desulfobulbaceae, and Sulfurimonadaceae, were significantly increased due to the polychaete bioturbation. The polychaete bioturbation reduced the complexity of the bacterial co-occurrence network while increased its modularity and homogeneity. The polychaete bioturbation also changed the functional groups, which significantly enhanced in functional groups of aerobic nitrite oxidation, nitration, dark thiosulfate oxidation, dark sulfur oxidation, and dark sulfite oxidation, while nitrogen respiration and nitrate respiration decreased. These results provide insight into the impact of bacterial communities under the intertidal polychaete bioturbation.