A comparison of microplastics in farmed and wild shellfish near Vancouver Island and potential implications for contaminant transfer to humans

This research compared numbers of microplastics in three species of farmed and wild shellfish collected near Vancouver Island, BC. Species included were blue mussel (Mytilus edulis), Manila clam (Venerupis philippinarum), and Pacific oyster (Crassostrea gigas). Soft tissue was chemically digested with nitric acid (68-70%) for 140 individuals. Significantly higher numbers of microplastics were observed in farmed blue mussels (P = 0.021) and Pacific oysters (P = 0.011), compared to their wild counterparts; whereas, no significant difference was observed between farmed and wild Manila clam (P = 0.093). Abundance of microplastics ranged from 5.6 microplastics/g to 657.5 microplastics/g, which are higher than any reported levels in the literature. White pellets were the most abundant microplastic particle (99%) recorded in all species. This research indicates microplastics are present in three commonly consumed shellfish species near Vancouver Island and presents a possible vector for contaminant transfer to humans.