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National audience; Les fleuves et cours d’eau représentent la principale voie de transport du plastique vers les océans : notamment, à travers les rejets d’eaux usées. Même si des études récentes montrent des effets toxiques des microplastiques sur des espèces marines, leurs mécanismes de toxicité et de transfert dans les chaînes alimentaires restent encore à élucider. Ceci est encore plus vrai pour les nanoplastiques pour lesquels les études sont rares. Afin de comprendre les effets des micro- et nanoplastiques sur les organismes aquatiques, il apparaît nécessaire de réaliser des études plus réalistes d’un point de vue environnemental. C’est pourquoi ce projet vise à étudier : 1. les caractéristiques physico-chimiques des micro- et nanoplastiques, leur toxicité et celle des contaminants associés ; 2. leurs conditions de dispersion dans l’eau selon le gradient de salinité ; 3. leurs effets chez des organismes aquatiques appartenant aux différents maillons de la chaîne trophique en caractérisant précisément l’exposome.

International audience; We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress

International audience; We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress

Cet article examine la manière dont les risques résultant de l’interaction entre l’eau douce et l’eau marine sur un territoire hybride, situé entre terre et mer – le littoral – amènent à interroger les modalités de gestion des ressources naturelles et de l’environnement. Après avoir rappelé le caractère bidirectionnel des risques sur le littoral lorsqu’ils sont véhiculés par l’eau, nous analysons deux approches de gestion intégrée : la gestion intégrée des ressources en eau et la gestion intégrée des zones côtières. Tout en reconnaissant de nombreux points communs à ces deux approches, nous soulignons la nécessité de dépasser cette distinction qui tend à cloisonner des politiques qui mériteraient, au contraire, d’être envisagées de concert. Enfin, en nous appuyant sur l’exemple du territoire des Wateringues, situé dans la région Nord-Pas-de-Calais, nous illustrons les défis auxquels sont confrontées ces zones domestiquées par l’homme depuis plusieurs siècles, mais soumises à de multiples pressions et lieux de conflits d’usage que les risques peuvent parfois exacerber. This article deals with the way hazards, resulting from the interactions between fresh and marine waters in coastal zones, lead to question the variety of management practices of natural resources and the environment. In a first step, we underline the bidirectional character of hazards driven by fresh and marine waters in coastal areas. We discuss, in a second step, two way of dealing with integrated management of natural resources in those areas: namely Integrated Coastal Zone Management (ICZM) and the Integrated Water Resources Management (IWRM). While it is easy to recognize a convergence in the philosophy of such processes, we stress the necessity to go beyond distinctions, in order to build a more comprehensive approach. Finally, with the example of the Wateringues territory, located in the North of France, we illustrate the stakes of an integrated approach, in an area characterized by multiple pressures, where use conflicts are sometimes strengthened by the presence of hazards.