Microplastics are a growing threat in aquatic environments worldwide, due primarily to the breakdown of larger plastic items through photodegradation and physical abrasion. While concentrations of microplastics can be much higher in urban and suburban watersheds, they appear to be ubiquitous in all environments, including the deep ocean. Microplastics have been shown to serve as vectors for other known contaminants in addition to disease transfer. Furthermore, microplastics can be ingested by a variety of aquatic organisms, entering the food chain and potentially impacting ecosystems and even human health. This webinar examined the state of knowledge of microplastic impacts in the environment, with a focus on coastal areas using the Chesapeake Bay (USA) estuary as an example of a multi-jurisdictional natural resource.