Plastic is the most prevalent type of marine debris found in our ocean and Great Lakes. Plastic debris can come in all shapes and sizes, but those that are less than five millimeters in length are called microplastics. There are a variety of types of microplastics—primary microplastics that are manufactured as microbeads or production pellets, and secondary microplastics (e.g., film, fragments, fibers, and foam) that are formed by the breakdown of larger plastics into smaller and smaller pieces. These tiny particles easily pass through water filtration systems and end up in the ocean and Great Lakes, posing a potential threat to aquatic life.

Marine debris and microplastics are an emerging field of study, and much is unknown about their impacts on aquatic ecosystems, particularly the long-term effects. While study of the fate, transport, and effects of plastic contamination in the oceans have been building for some time, similar knowledge in freshwater systems is greatly lacking. The ecosystem impact of plastic litter (from nano- to micro- to macro-sized) in the Great Lakes is a growing area of research. The impacts of this emerging contaminant will be difficult to manage in the future without a robust, well-coordinated, evidence-driven knowledge base.