The study “Microplastics in the marine environment: Sources, Impacts & Recommendations”, has been commissioned by Seas At Risk to the Galway Mayo Institute of Technology which has a long standing focus and expertise on microplastics. The study includes a meta-study of the existing literature on microplastics and the marine environment reviewing all sources of microplastics as well as the corresponding environmental and climate impacts. It also compiles the views of 23 microplastic experts from 15 countries on how to effectively monitor microplastic pollution with indicators and provides decision-makers with 80 short, medium and long-term recommendations on how to effectively prevent the release of microplastic into the environment.