Eutrophication is one of the most common causes of water quality impairment of inland and marine waters. Its best-known manifestations are toxic cyanobacteria blooms in lakes and waterways and proliferations of green macro algae in coastal areas. The term eutrophication is used by both the scientific community and public policy-makers, and therefore has a myriad of definitions. The introduction by the public authorities of regulations to limit eutrophication is a source of tension and debate on the activities identified as contributing or having contributed decisively to these phenomena. Debates on the identification of the driving factors and risk levels of eutrophication, seeking to guide public policies, have led the ministries in charge of the environment and agriculture to ask for a joint scientific appraisal to be conducted on the subject. Four French research institutes were mandated to produce a critical scientific analysis on the latest knowledge of the causes, mechanisms, consequences and predictability of eutrophication phenomena. This paper provides the methodology and the main findings of this two years exercise involving 40 scientific experts.

The need for better conciliation between food production and environmental protection calls for new conceptual approaches in agronomy. Ecological intensification (EI) is one of the most encouraging and successful conceptual frameworks for designing more sustainable agricultural systems, though relying upon semantic ambivalences and epistemic tensions. This article discusses abilities and limits of the EI framework in the context of strong social and environmental pressure for agricultural transition. The purpose is thus to put EI at stake in the light of the results of an interdisciplinary and participatory research project that explicitly adopted EI goals in livestock semi-industrialized farming systems. Is it possible to maintain livestock production systems that are simultaneously productive, sustainable, and viable and have low nitrate emissions in vulnerable coastal areas? If so, how do local stakeholders use these approaches? The main steps of the innovation process are described. The effects of political and social dynamics on the continuity of the transition process are analyzed, with a reflexive approach. This experiment invites one to consider that making EI operational in a context of socio-technical transition toward agroecology represents system innovation, requiring on-going dialogue, reflexivity, and long-term involvement by researchers.

La gestion de la qualité de l’eau est soumise à deux injonctions : un impératif scientifique et un impératif participatif. Au travers de notre expérience de chercheuses en sciences sociales engagées dans quatre démarches de protection associant des projets de recherche souvent pluridisciplinaires, cet article propose un retour réflexif sur les attentes exprimées par rapport à notre participation, ainsi que sur l’évolution de notre positionnement. Il apparaît alors que la place des chercheurs en sciences sociales n’est jamais totalement acquise, parce qu’elle produit des connaissances essentiellement dialogiques, dont les objets se déplacent et se transforment au fil des enquêtes et des interactions avec les porteurs d’enjeux. C’est finalement moins par l’intervention directe que par la réorientation de nos questions de recherche vers des problématiques liées à ces enjeux que nous avons pu partiellement contribuer aux dispositifs de gestion des pollutions diffuses d’origine agricole.

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