19 Juillet – Thesis defense - Charlotte Lefebvre

14 h Petit Amphithéâtre de Biologie Animale (PABA) - Building B5 (Unversity of Bordeaux - Bordes campus)

Spatial and temporal distribution of microplastics and anthropogenic particles in a mesotidal coastal lagoon, the Arcachon Bay (France). Multi-compartment approach.

As a cheap, light and resistant material, plastic rapidly became unavoidable in many sectors such as packaging, medical, automobile or building ones. However, theses extraordinary properties contribute to its ubiquity in marine environments, and sometime in an insidious way. Indeed, there is a fraction invisible to the naked eyes, named microplastic (MP), that draw researchers’ attention. They are commonly described by an upper limit size of 5 mm, yet the lower size limit is still under discussion. Meantime, other types of manufactured particles are more and more described, such as black rubbery fragments and fibers. These anthropogenic particles (AP) were already detected in marine compartments of all regions, from sea surface to bottom sediments by the way of beach, water column and living organisms. Nevertheless, MP contamination could be associated to impairment of geochemical cycles and biologic ones. Actually, because they are small-sized, MP can be ingested by a wide range of marine organisms (from zooplankton to cetacean). Additionally, the Arcachon Bay area supports important and diverse anthropogenic activities such as fishing, shellfish farming and mass tourism. Additionally, the lagoon have a complex morphology (e.g. intertidal areas and passes) and its hydrodynamic is mainly driven by tide. Thus, this project describes AP and MP contaminations in the Arcachon Bay, such as the one caused by fibers. Specifically, we were able to 1) quantify and characterize AP and MP contamination in nine compartments of this lagoon (sea surface, water column, wastewater effluent, intertidal sediment, high tide line, marine species), 2) describe their spatial distribution (from the oceanic zone to the inner-bay part) and explore transport dynamic between compartments, 3) characterize temporal evolution of the contamination within the studied compartments.

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