The plastic Trojan horse: Biofilms increase microplastic uptake in marine filter feeders impacting microbial transfer and organism health

Microplastic pollution has become a major source of concern, with a large body of literature surrounding the impacts of microplastic ingestion by biota. However, many of these studies utilise virgin microbeads, which are not reflective of environmental microplastics that are rapidly colonised with microbial communities (plastisphere) in marine ecosystems. It is a concern therefore that current evidence of the impacts of microplastics on biota are unrepresentative of the environmental microplastic pollution. In this study, uptake and bioaccumulation of both virgin and Escherichia colt coated microplastics, by European native oysters (Ostrea edulis) were compared, and the physiological responses of oysters to the exposure were investigated. The uptake of E. coli coated microplastics was found to be significantly higher than the uptake of virgin microplastics, with average concentrations of 423 +/- 23.5 no. g(-1) and 11.4 +/- 0.6 no. g(-1) microbeads found in oysters exposed to coated and virgin microplastics, respectively. This suggests that environmental microplastic uptake into the marine trophic web by benthic filter feeders may be greater than previously thought. The oxygen consumption and respiration rate of oysters exposed to E. coli coated microplastics increased significantly over time, whilst virgin microplastics did not produce any measurable significant physiological responses. However, less than 0.5% of the total amount of administered microbeads were retained by all oysters, suggesting a limited residence time within the organisms. Although microplastics did not bioaccumulate in oyster tissues in the short-term, microorganisms assimilated by the ingestion of coated microplastics may be transferred to higher trophic levels. This poses a risk, not only for wildlife, but also for food safety and human health. The capacity to carry pathogens and expose a wide range of organisms to them means microplastics may have an important role as vectors for disease. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

The study found that uptake of E. coli coated microplastics was significantly higher than that of virgin microplastics in European native oysters, with oysters exposed to coated microplastics also showing increased oxygen consumption and respiration rate over time compared to those exposed to virgin microplastics. Despite microplastics not bioaccumulating in oyster tissues in the short-term, microorganisms assimilated by ingestion of coated microplastics may be transferred to higher trophic levels, posing a risk to wildlife, food safety, and human health. Microplastics have the potential to act as vectors for disease by carrying pathogens and exposing a wide range of organisms to them.