Abstract: Microbial community structure and diversity in marine environment are important indicators for assessing structure and function of marine ecosystems. To understand the characteristics of bacterioplankton communities in Xiangshan Bay, to compare the bacterial composition and structure in different habitats, and to assess the causes of community differences in different habitats, 16S rRNA gene high-throughput sequencing was employed to evaluate the bacterial structure and diversity in marine water samples collected from artificial reef area (AR), natural control area (NC), oyster culture area (OC), and cage culture area (CC) of Xiangshan Bay. Results showed that a total of 46 phyla were detected, including Proteobacteria (50.74%), cyanobacteria (13.80%), actinobacteria (13.51%), Firmicutes (10.02%), and Bacteroidetes (9.63%). Among all the habitat types, the dominant bacterial community composition of seawater samples from the AR, NC and OC habitat was similar, but a great difference was found between them and samples from the CC habitat (P<0.05). The abundance and diversity of bacterial community were higher in the AR habitat, but lower in the OC and CC habitat (the lowest in the CC habitat). Marine environment of the OC was relatively stable, without significant change in microbial community structure and diversity. The deployment of artificial reef improved the marine ecological environment, which was beneficial to the diversity and stability of bacterial structure in the corresponding area, while the cage culture in offshore area caused the change of bacterial community to an unstable structure with reduction in diversity.

Key words: bacteria, community structure, cage culture, artificial reef.