Spatial and temporal variation of microbial populations and microbial metabolic potential in a tropical marine cage-culture sediment system

The ecological roles of benthic microbes and the effect of anthropogenic mariculture activities on sediment microbial communities remain largely unexplored. Here, sediment bacterial abundances and diversity and their response to the disturbance induced by marine cage-culture farming were investigated at the station of Maniao Bay, Hainan province, China, with a history of cage culture for approximately 20 years. We characterized the sediment-associated microbial populations taken at marine cage culture zones and non-mariculture zones across one year. However, no significant differences between the marine cage culture and the non-mariculture zone occurred in microbial community structure and diversity. Minor differences among microbial communities during the year were observed in the sampling sites, which may be driven by the content of organic matter and sulfide in the sediment. This fact indicated that the diverse sediment microbiome was resilient to the stress caused by a modest environmental change. On the other hand, the ecological roles of the benthic microbes were explored by metagenomics, and their response to the marine cage-culture farm biodeposition was investigated across three years. The biochemical function carried out by the sediment microbes showed no significant difference between the marine cage culture zone and the non-mariculture zone. A stable microbial community was revealed in the Maniao Bay mariculture area and its adjacent sea area, which might be promoted by the hydrodynamic characteristics of the aquaculture area and its adjacent sea area, aquaculture scale, and culture mode.