This document summarizes Robyn Elizabeth Jones' MSc thesis on the effects of microplastics on marine biota. The study aims to examine if ingestion of microplastics negatively impacts the common mussel Mytilus edulis and whether these microplastics are transferred to the mussel's predator, the dog whelk Nucella lapillus. The methodology will expose mussels to different microplastic concentrations over various time periods and examine plastic accumulation in their guts. Mussels will then be fed to dog whelks to see if microplastics transfer through the food web. Beach surveys will also quantify microplastic contamination along the North Wales coastline. Statistical analysis will compare plastic ingestion across exposure conditions and