Plastic impacts on Ocean's biogeochemical cycles in the Anthropocene

ended

The long-term accumulation of plastic in our ocean has become a global challenge. Microplastics, and particularly those < 300 µm, are ubiquitous and persistent and get entangled in microbial organic matrices that change particles’ buoyancy, aging, and determine their bioavailability in the water for being ingested. Microplastics’ interaction with microorganisms may also change microbial communities distribution and activity, possibly perturbing biogeochemical cycles at the basis of marine ecosystems and food webs. Through primary production the ocean absorbs and converts atmospheric carbon dioxide into organic matter, further channelled to higher trophic levels by its incorporation into bacterial biomass, and thus provides up to 70% of the oxygen for life. PLOCEAN focuses on how microplastics interact with the microbial mechanisms of production and transformation of organic matter to address important research priorities: 1) plastic sources and distribution in marine environments; 2) biogeochemical processes driving plastics’ aging, transport and bioavailability affecting fish stocks and human consumption; and 3) the role of plastic in marine biogeochemical cycles that may determine changes in carbon turnover, nutrients cycling and primary productivity in coastal areas. PLOCEAN will combine field observations and laboratory studies applying the latest developments in research techniques: polymer characterization and metagenomics to study plastic-specific microbial communities, microbial contribution to particles' aging and interaction with organic matrices. PLOCEAN will also devote an important aspect to outreach and citizen science. The multi-disciplinary approach and the research questions addressed will contribute to fill knowledge gaps in the current understanding of environmental plastic fluxes, distribution, as well as impacts on biotic and abiotic marine compartments that affect biogeochemical processes behind marine ecosystem’s food webs and functioning.