Abstract Summary
As public awareness around the issue of marine litter and microplastics increases, so do public and private sector measures to reduce waste in the ocean. However, the extent of marine litter and microplastic (ranging from 0.2 mm to 0.5 mm) occurrence across ocean biomes and species remains poorly characterized, particularly in remote difficult to access places such as the deep ocean, making it challenging to assess where spatial management is needed and what measures would help achieve this. For example, the United Kingdom declared large knowledge gaps for the seafloor environment and a lack of baseline values to help set targets towards implementing the European Union’s Marine Strategy Framework Directive (MFSD) that sets out to ensure Good Environmental Status (GES) of European waters by 2020. The MFSD establishes 11 descriptors to assess GES, this study focuses on Descriptor 10: that marine litter does not cause harm. The present study is the first assessment of marine litter and microplastics in a continental shelf marine protected area (MPA) in UK waters. Extent of marine litter was quantified at two (Mingulay and Banana) cold-water coral reefs in the East Mingulay MPA (Sea of the Hebrides) through systematic reviews of seven research expedition reports from 2003 to 2012 and annotating 41 hours of video surveys conducted in 2012. Reviews of expedition reports resulted in 6 recorded instances of litter out of 217 benthic stations. In every case the litter was fishing related; nets, rope, gear and plastic tarpaulin. Microscopic analysis of trypsin-digested gut contents from benthic reef macrofauna (n=112) showed 9% had ingested microplastics, all within the 0.2 - 0.5mm size fraction. Ingestion differences in microplastic occurrence were observed across feeding guilds, with microplastics observed more frequently in suspension and filter-feeders. Besides establishing a baseline assessment of marine litter and microplastics in this MPA, the approach demonstrates the utility of using historic data and specimens collected for other purposes to expand the geographic and ecosystem coverage for GES assessments.
