Marine microplastic-associated biofilms – a review

Environmental context Marine microbial communities, which play a crucial role in all biogeochemical processes in the oceans, could be affected by microplastic pollution. Research is necessary to understand the interactions between marine microbial communities and microplastics, and to explore the potential for microplastics to serve as transport systems for pathogenic microorganisms. Our review summarises first insights into these topics and discusses gaps in our current knowledge. Abstract The accumulation of plastic in the marine environment is a long-known issue, but the potential relevance of this pollution for the ocean has been recognised only recently. Within this context, microplastic fragments (<5 mm) represent an emerging topic. Owing to their small size, they are readily ingested by marine wildlife and can accumulate in the food web, along with associated toxins and microorganisms colonising the plastic. We are starting to understand that plastic biofilms are diverse and are, comparably with non-plastic biofilms, driven by a complex network of influences, mainly spatial and seasonal factors, but also polymer type, texture and size of the substratum. Within this context, we should raise the question about the potential of plastic particles to serve as vectors for harmful microorganisms. The main focus of the review is the discussion of first insights and research gaps related to microplastic-associated microbial biofilm communities.