The impact of microplastics on small organism dispersal: mechanisms, risks, and research gaps

Abstract Microplastics (MPs), small plastic particles under 5 mm, are increasingly recognized for their environmental persistence and ubiquity across ecosystems. While research has long focused on MPs’ toxicity, their influence on the dispersal of small organisms, including fungal, bacterial, and viral pathogens and their vector species such as insects, is gaining attention. This perspective examines how MPs could act as carriers for microorganism dispersal via the formation of unique biofilms, termed as ‘plastisphere,’ which hosts diverse microbial communities and facilitates horizontal gene exchange, including antibiotic-resistant genes. We also explore indirect impacts, as MPs influence the physiology and life history traits of organisms, which can alter dispersal dynamics. Despite increasing interest, significant research gaps remain, particularly concerning MPs in terrestrial ecosystems and the effects of biofouled versus pristine MPs in natural settings. Additionally, inconsistent methodologies, such as the use of unrealistically high MP concentrations and the lack of control materials or systematic experimental design challenge current research, limiting a comprehensive risk assessment. Addressing these limitations is essential to accurately evaluate MPs’ role in the dispersal of small organisms and to inform potential policy measures.