Impact of microplastics on microbial diversity and pathogen distribution in aquaculture ecosystems: A seasonal analysis

Microplastics, as a prominent emerging pollutant in marine environments, pose a serious threat to the stability of marine ecosystems due to their resistance to biodegradation. MPs act as substrates for biofouling and potentially promote the spread of harmful microorganisms. Research indicates that human activities exacerbate MPs pollution in aquaculture environments, significantly increasing their abundance. This study focused on the aquaculture environment of the large yellow croaker (Larimichthys crocea), one of the most extensively farmed fish species in coastal regions. We conducted a comprehensive analysis of microbial diversity on the biofilms covering MPs and in the surrounding aquaculture water, with a focus on the distribution of pathogens on MPs. Furthermore, this study investigated the impact of seasonal variations on the microbial communities within these biofilms. Sequencing analysis revealed that the α-diversity of microbial communities on MPs was lower than that in aquaculture water during winter but higher in summer, indicating a seasonal shift in microbial community structure. PICRUSt predictions suggested that microbes on MPs possess unique metabolic pathways. Co-occurrence network analysis demonstrated that during summer, the microbial communities on MPs revealed increased connectivity and functional modularity, whereas microbial communities in aquaculture water showed stronger interactions in winter. Additionally, several potential pathogens, including Vibrio and Pseudomonas, were detected in the MPs biofilms. These findings underscore the ways in which MPs influence the microbial community structure in aquaculture environments, increasing health risks to the ecosystem. This research offers significant insights into the ecological impacts of MPs pollution on microbial communities in aquaculture ecosystems.