Microplastics form a dispersal-limited artificial niche that selectively enriches potential plastic-degrading...

Microplastics (MPs), as emerging pollutants, accumulate extensively in aquaculture areas, yet their microbial ecological functions and associated risk mechanisms remain poorly understood. In this study, we collected water, sediment, organic, and MP samples across spring and autumn from a representative aquaculture area in southeastern China. Using high-throughput 16S rRNA sequencing, community ecological modeling, functional prediction, and network analysis, we systematically investigated the diversity, assembly mechanisms, and ecological functions of the "plastisphere" bacteria. Results indicated that habitat type was the primary driver of bacterial community structure, while season acted as a secondary factor modulating community composition across different environments. Although MPs shared certain core microbiota with organic, their attached bacterial communities differed markedly from those on water, sediment, and organic. Neutral model analysis revealed extremely low migration rates between MP and organic surfaces (m = 0.011), suggesting that MPs form an independent and dispersal-limited artificial niche. Co-occurrence network analysis further showed that MPs surfaces were dominated by potential plastic degrading bacteria and conditionally pathogenic taxa, whereas organic communities exhibited saprophytic traits. Functional prediction revealed that MPs were significantly enriched in human disease-related and hydrocarbon-degrading functions, maintaining stability across seasons. This study demonstrates that MP surfaces attached bacteria in marine aquaculture areas simultaneously possess pollution remediation potential and public health risk attributes, providing new insights for assessing the ecological effects of MPs and attached microbiota and informing aquaculture management strategies.