Are British Columbia blue mussels ingesting and retaining microplastics

Microplastics are plastic polymers mammals, sea turtles and sea birds, down to bivalves, echinoderms and zooplankton. For the first time, microplastic abundances will be reported for blue mussels (M. edulis) in the Strait of Georgia, British Columbia. Individuals of the same genetic stock were deployed in cages within the Strait of Georgia between January and March, 2017. A total of 11 survey sites were included of varying anthropogenic disturbance. During each sampling period, mussels and water quality data were collected on day 0, 30 and 60 of the field survey. Using rigorous contamination control techniques and an enzymatic digestion (Corolase 7090), individual mussels were processed over an 18-hour period at 60°C. The resultant digested samples were then filtered through a 20µm polycarbonate filter for quantification using light microscopy (length, width, colour and shape where characterized). Polymer type was identified using Fourier-Transform Infrared Spectroscopy and a comprehensive data set of polymer composition and abundances established. Results are being compared to determine temporal and spatial differences between sites to determine if microplastics accumulate in these filter feeding organisms. Preliminary numbers are low, indicating that blue mussels are unlikely to accumulate microplastics within the body cavity. These findings may be a result of low environmental contamination, an ability by this species to eliminate microplastics post ingestion and/or selection against microplastics outright. Further results will help shed light on the initial notion that blue mussels may have the capacity to reject or eliminate microplastics and are not as vulnerable to contamination as other shellfish such as clams and oysters.