Pollution by plastic particles is a major environmental concern in aquatic environments. Numerous studies have been carried out to assess the toxicity of microplastics (MPs), and more recently nanoplastics (NPs), for aquatic organisms. However, some aspects have so far been little studied. The majority of studies focus on the effects of plastic particles in the marine environment while estuarine and freshwater environments are little studied despite their important role in the transfer of plastics to the environment. In addition, the potential transfer of MPs and NPs into aquatic trophic chains, for example, is currently poorly understood. This led us to develop a multidisciplinary approach to better understand the effects of MPs and NPs, representative of those found in an estuary, on key species from a food chain living in the freshwater-marine water continuum. The food chain includes phytoplanktonic algae Scenedesmus subspicatus and diatoms Thalassiosira weissflogii (first trophic levels), endobenthic bivalve molluscs Corbicula fluminea and Scrobicularia plana (second trophic levels) and the European eel Anguilla anguilla (third trophic level). The impacts of MPs and NPs on aquatic species are assessed by both direct route and trophic route and are characterized using a multi-marker approach ranging from effects at the individual level (physiological, behavioral) to the sub-individual level (molecular, biochemical, microscopic). This talk will focus on the preliminary results of the direct exposures of the mollusc bivalves to plastic particles.