PLASTIC-Seine research project: Microplastic Flux and Impact on biota in the Seine estuary.

International audienceMicroplastics (MP) pollution is of emerging concern. Although numerous studies were recently carried out on freshwater and biota contamination, studies focused on estuary ecosystems are scarce. Estuaries can indeed play a significant role in the transport and transfer of MP to the ocean and the estuarine hydrodynamics and salinity gradient can greatly affect both MP distribution and concentrations, as well as the occurrence and levels in biotic compartments. In this context, the Plastic-Seine project (2017-2020) involving six French laboratories was launched to study the occurrence and levels of MP in all compartments of the ecosystem of the Seine River estuary (France). The objectives are: i) to study the occurrence and levels of MP in the Seine estuary for abiotic compartments (water column and sediment), ii) to study the ingestion and levels of MP for seven emblematic species of the Seine estuary, i.e, the worm Hediste diversicolor, the copepod Eurytemora affinis, the mussel Mytulis edulis, the prawn Palaemon longirostris and 3 fish species Platichthys flesus, Solea solea and Dicentrarchus labrax and iii) to assess the potential impacts of MP exposure on biology traits, physiologyand behavior of three species (Hediste diversicolor, Eurytemora affinis and Solea solea). Preliminary and main results are here presented and discussed. First results on abiotic compartements highlighted the presence of fibers and fragements in both the water colonn and sediments. Particles exhibited different forms depending on their origin and/or fragmentation. Most of particles were inferior to 1 mm and a high proportion of fragments and films was higlighted. Slight MP distribution changes were also observed between surface water and subsurface water. For the seven species, MP including fibers and fragements were found. The others analyses are in progress. For all species, a high variabilities between species and individuals was highligted. High presence of fragments were noticed for seabass and worms in comparison to other species. In the case of prawns, a large amount of MP and especially of fibers were also observed on the cuticle surface. Futher studies will investigate the potential impacts of MP exposure onbiology traits, physiology, and behavior of three estuarine species and the MP trophic transfer to common sole’s food chain