Bottles, packaging, cigarette butts, bags, fish nets, etc. An ocean of plastics! Human-generated litter is present everywhere in the ocean, even in the deep sea. Massively produced over the past 60 years, plastics are materials that have turned into long-lived litter, decomposing all too slowly and gradually accumulating in the oceans. Although the scientific community has long studied the quantification of “macro-litter” (bottles, bags, nets, etc.), the dynamics of this plastic litter and the microplastics in the ocean are still largely unknown.
Where do these microplastics come from? They come mainly from pieces of land-borne plastic discharged into the oceans. These pieces of plastic break into fragments due to the action of currents, UV light, temperature, bacterial degradation and mechanical actions. Some microplastics originate from industrial waste generated by the personal-care products (exfoliants, toothpaste), petrochemistry (pre-production plastic resin pellets, industrial abrasives) and clothing (synthetic fibres) industries.
Scientists are confronted with the challenge of sampling and identifying microplastics with sizes close to one micrometre (1 µm or 0.001 millimetre). The high rate of breakdown of primary plastics hinders the quantification of ocean plastic debris. It is not known how microplastics are fragmented, transported and dispersed in the marine environment, whether at the surface, in the water column or in the deep sea. Nor their impact on marine organisms. Which microorganisms can adhere to plastics (biofouling1) and how they adhere. A better understanding of the interactions between marine biodiversity and microplastics at various scales, from the cell to the community, is necessary for gaining an overall understanding of the problem.
“Given the immensity of the ocean, the Microplastics project is a scientific adventure in a miniature world in which everything remains to be discovered,” underlines Emina Mamaca, the coordinator of the Microplastics project.
The Microplastics project has four main goals:
- Trace the smallest plastic particles to better understand their fate and assess their impact and develop novel technological tools to collect, characterise and quantify them.
- Assess the role of microplastics as a new habitat for microbiota via a better understanding of the “plastisphere”. Scientists will also investigate how microplastics are transferred in the food chain via the species that ingest them. The role of microplastics as a vector of microorganisms including pathogens (bacteria, viruses, microalgae) will be analysed as well as certain physical effects (mechanisms of ingestion) and chemical effects, particularly chemical contaminants that are likely dispersed by microplastics (certain pesticides).
- Characterise the presence of microplastics in the deep sea, with extensive research in the archives available at IFREMER from the past 20 years, and studying interactions with meiofauna, the microscopic biodiversity of the deep seabed.
- Sample these materials in several pilot areas off the French coast, particularly in the Mediterranean Sea, using a citizen-science approach involving local populations. Hence, new methodological approaches will need to be developed for sampling and analysis.
The Microplastics project will be conducted by IFREMER in collaboration with LEMAR the Marine Environmental Sciences Laboratory (UMR CNRS/UBO/IRD/IFREMER), CEDRE (Centre for Documentation, Research and Experimentation on Accidental Water Pollution), the LABOCEA laboratory, the private company HORIBA (manufacturer of precision instruments and optical equipment for measurement and analysis) and the IPCF (Italian Institute for Chemical-Physical Processes). Microplastics will cooperate with the ANR Nanoplastics project (IMMM, University of Maine) on certain aspects involving major methodological developments, such as the collection and characterisation of the smallest plastic particles. ANR-Nanoplastics began in 2016 for a duration of 4 years.
 Biofouling is the formation of an unwanted layer of living organisms or microbes on an artificial surface in permanent or at least frequent contact with water (litter, boat hulls, immersed chains, buoys, etc.).