Impact of marine aquaculture wastewater discharge on microbial diversity in coastal waters

Abstract

Numerous pollutants exist in marine aquaculture wastewater, such as organic matter and antibiotics, with uncontrolled discharge affecting both marine and coastal ecological environments. Microbial communities respond sensitively to changes in aquatic environment, exhibiting altered species numbers and population composition. In this study, NGS technology was applied to analyze the composition and diversity of microbial communities in marine aquaculture ponds and the surrounding seawater. The analysis aimed to explore the relationship between microbial diversity in the marine aquaculture industry and the surrounding marine environment, with Dongzhai bay selected as the research object. Water samples were collected from five sampling points, according to marine aquaculture water discharge and diffusion patterns. The dominant bacteria included Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria, while the dominant fungi included Ascomycota, Basidiomycota, Mortierellomycota, and Rozellomycota. Diversity within microbial communities was found to be related to environmental factors such as pH, NH4+-N, COD (Chemical Oxygen Demand), and TN (Total Nitrogen). Unique microbial species were found to exist in different environments. According to the analysis of OTUs and Alpha diversity, the population and species diversity of microbial populations in P. vannamei culture ponds were lower than in other areas, while mangrove areas showed increased microbial diversity in comparison to other areas. Results showed that the discharge of aquaculture water results in eutrophic substance diffusion in different areas of the bay, which in turn affects the surrounding oceanic microbial community.