Berlin Highlights— Plastics: An Emerging Risk to the Marine Environment
Courtney Arthur (NOAA)
Anthropogenic debris enters the marine environment from a variety of sources, often due to poor waste management systems. This "marine litter" or "marine debris" is composed of solid, persistent manufactured materials used or transported on land as well as the ocean (e.g., abandoned and derelict fishing gear). A significant portion of marine debris is composed of thermoplastic and thermosetting polymers, which attract attention due to high visibility when floating in surface waters. In addition, sorptive properties of polymers enable them to concentrate and transport hydrophobic organic contaminants in the marine environment. As plastics fracture into smaller and smaller pieces, they retain the capability for sorption, long-range transport and ingestion by aquatic organisms. As a result, it has been suggested that plastic debris may be considered an emerging contaminant in aquatic systems.
The occurrence and effects of plastic debris were discussed during platform and poster sessions. Session chairs were pleased to elevate this topic to the World Congress audience. Significant gaps exist in developing a complete understanding of the occurrence and risk of plastic debris. Thus, continued research and communication about this global phenomenon is necessary to develop appropriate long-term solutions and mitigation strategies.
New research was presented on the occurrence and composition of plastic debris, chemical sorption and leaching potential, advances in detection, and uptake of debris by marine organisms. Increasingly, the topic of plastics and microplastics is a research focus for scientists instead of existing as a tangent to a related research agenda. Students are beginning careers in this emerging field, such as Lisbeth van Cauwenberghe (Ghent University) whose description of microplastics uptake in bivalves won the Young Scientist Award for best poster. Other session highlights included descriptions of environmental loads that emphasized highly variable concentrations and the many factors that influence movement and fate. Gaps in understanding were discussed, such as background contamination from synthetic fibers in laboratory quantification of microplastics; lack of particle concentrations for biota, sediments and water from the same site; lack of reporting particle size and weight that will inform toxicological assessments; and lack of leaching protocols for polymers. Many of these challenges point to a need for additional method development. A number of presentations focused on plastic ingestion, including detection of microplastic fragments in all field-collected mussel and marine worm tissues; suggested use of the Mediterranean fin whale as a sentinel of plastic debris accumulation for the Marine Strategy Framework Directive; and correlation of some BDE congeners with plastics ingested by surface-feeding seabirds. Additionally, presentations investigated DDT desorption from plastic fragments, which was shown to occur more quickly under gastric conditions than in aqueous environments, and polymer-dependent leaching rates for flame retardant chemicals.
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