Plastisphere-biofouling nexus: a systematic and bibliometric synthesis of emerging microbial assemblages on...

Microplastics in coastal waters provide persistent surfaces for microbial colonization and biofilm formation, supporting complex microbial assemblages known as the plastisphere. This study examines the plastisphere-biofouling nexus through a PRISMA-guided systematic review, bibliometric mapping, narrative-quantitative synthesis, and conceptual evidence integration of studies published between 2015 and 2025. From 1,248 records identified in Web of Science Core Collection and Scopus, 124 primary studies were retained for comparative synthesis. The reviewed evidence shows that microplastics frequently support distinct biofilm-associated microbial communities, although reported patterns vary across polymer type, exposure duration, environmental setting, microbial method, and biofilm measurement approach. Proteobacteria and Bacteroidetes were repeatedly reported among dominant bacterial groups, while opportunistic genera such as Vibrio and Pseudoalteromonas were detected in some plastisphere biofilms. Evidence for polymer-specific microbial diversity, contaminant retention, and environmental-driver effects remains context-dependent. Biofilm-coated microplastics may modify contaminant interactions under specific conditions, but current evidence does not support universal contaminant enhancement, confirmed pathogen transmission, or direct human health risk. This review identifies the plastisphere-biofouling nexus as an emerging ecological interface in coastal waters and highlights the need for standardized, field-relevant, and functionally validated studies.