Towards a management strategy for microplastic pollution in the Laurentian Great Lakes—ecological risk assessment and management (part 2)

Over the past decade, plastic pollution has been documented throughout the Laurentian Great Lakes basin. Here, we demonstrate the application of published ecological risk assessment and management frameworks for microplastics in aquatic environments by comparing proposed risk thresholds derived using toxicity data from both freshwater and marine species to local monitoring data. Our results suggest that there may be measurable risks from microplastics to aquatic communities in parts of the Great Lakes where current concentrations are relatively high. For example, concentrations in 89% of surface water samples collected across the region exceed the proposed risk thresholds for food dilution toxicity. However, concentrations in all sediment samples remain below the proposed risk thresholds. Accordingly, we suggest that an appropriate and necessary next step for management may include convening a working group of local experts to develop an ecological risk assessment and management framework for the region comprising risk thresholds for microplastics in surface water and sediment. Ultimately, microplastic pollution should be addressed in the Great Lakes Water Quality Agreement to ensure coordinated and sustained efforts are taken by the governments of Canada and the United States to reduce their release and impact.