DO ENVIRONMENTALLY RELEVANT CONCENTRATIONS OF MICROPLASTICS POSE A THREAT TO THE EASTERN OYSTER, CRASSOSTREA VIRGINICA?

It is well known that microplastics are ubiquitous within the marine environment and that organisms are interacting with them. However, information on the potential impacts this pollutant may have on an organism are less well understood, especially in response to environmentally relevant microplastic concentrations The aim of this study was to determine if environmentally relevant microplastic exposure has any physiological impact on the eastern oyster, Crassostrea virginica. We exposed C. virginica to daily doses of polyester microfibers based on concentrations reported from the field (0, 2, & 95 fibers L-1) as well as a higher concentration similar to those used in previous exposure studies (950 fibers L-1) for 45 days. To quantify the potential impacts of plastic exposure on C. Virginica physiology, we assessed somatic growth, survival, clearance rate, cellular energy allocation (CEA), and plastic accumulation in somatic tissues. No significant alterations were observed in any of the measured parameters, suggesting that environmentally relevant concentrations of polyester microfibers may pose little threat to the physiological wellbeing of C. virginica. Substantial variation was observed in the amount of fibers that accumulated per oyster demonstrating individualistic interactions between oysters and microplastics as well as the need for sufficient sample sizes in order capture this natural variation. Results from our study also highlight the importance of assessing and quantifying microplastic behavior within experimental tank water in order to truly understand exposure patterns and better interpret experimental outcomes. This study demonstrates the importance of considering environmental relevance when conducting microplastic exposure studies and the significant influence it may have on the observed impacts of a study. Such information is beneficial for waste management organizations to establish realistic and effective management strategies to deal with this emerging pollutant