Fish and Shellfish Aquaculture Impact on the Sediment Bacterial Communities in Xiangshan Bay, China

As the increase of demand for seafood supplies, a large amount of high-protein feed has been added to mariculture aeras, which causes hazards for the cultured organisms and environment. Here, we used 16S rRNA gene high-throughput sequencing to evaluate the bacterial communities in the sediments of two aquaculture systems (fish and oyster culture) in Xiangshan Bay, China for four seasons. Analysis of variance results showed that the abundance and biodiversity differed significantly between the culture areas and control areas, and different seasons as well. Proteobacteria, Planctomycetes, and Bacteroidetes were the three most abundant phyla. Gammaproteobacteria, Deltaproteobacteria, and Bacteroidia were the three most abundant classes. Principal co-ordinates analysis showed that sediment bacterial community composition in the fish and oyster culture areas significantly differed from that in the control areas. Analysis of the function prediction of pathways related to the nitrogen cycle in sediments revealed a higher proportion of genes involved in denitrification in aquaculture farms. Nitrate respiration particularly occurred in fish areas, whereas nitrate reduction occurred both in fish and oyster areas, and the proportions in winter were significantly higher than that in other seasons. It also provides insights into the indirect effects of human aquaculture activities on coastal algal blooms.