Extent of microplastics in Pacific Sand Lance burying habitat in the Salish Sea

Extent of microplastics in Pacific Sand Lance burying habitat in the Salish Sea Willem Peters MRM candidate Simon Fraser University, Dr. Cliff Robinson Department of Fisheries and Oceans, Dr. Karen Kohfeld Simon Fraser University, Dr. Marlow Pellatt Parks Canada, Dr. Doug Bertram Environment and Climate Change Canada School of Resource and Environmental Management, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6 CANADA, willemp@sfu.ca The ingestion of microplastics by forage fish and their subsequent accumulation and transfer up the coastal food web is a growing concern to scientists, government, fisheries, and the health sector. One key forage species in the Salish Sea, the Pacific sand lance (Ammodytes personatus), buries in low silt, medium coarse sand patches from chart datum to 100 m depth. In the southern Salish Sea near Sidney, several of these burying habitats are located in the vicinity of sewage discharge pipes and may be subject to microplastic accumulation. This research assesses the level of microplastic accumulation in Pacific sand lance burying habitats in the Salish Sea. Seafloor sediment samples were collected in Spring-Fall 2017, using a Van Veen grab sampler. Samples were collected at different distances from shore and effluent discharge pipes, and from a variety of depths and tidal currents. Microplastic concentrations were determined from the sediment samples in the laboratory using standard methods, while controlling for contamination. The main results indicate a significant correlation between suitable Pacific sand lance burying habitat and higher microplastic concentrations. We also found a strong imbalance of microplastic type and colour, with blue fibres making up the majority of microplastics found. The relationship between microplastics and Pacific sand lance habitat suitability is not intuitive in that higher concentrations of microplastics were found in sediments that suggest higher current rates, where settling dynamics would suggest that fewer particles would settle. Possible explanations include evacuation of microplastics from sand lance when buried, the proximity of suitable habitat to effluent discharge, or other as yet unexplored factors. Overall, the presence of microplastics in the burying habitats and stomachs of Pacific sand lance (as noted in other research) indicates more research is required to understand the implication to higher trophic level species that feed upon Pacific sand lance, such as chinook and coho salmon, various groundfish, fish-eating alcids, and marine mammals such as the humpback whale. Ultimately, strategies to reduce microplastics entering the Salish Sea will need to be implemented.