Coastal lagoons are important for coastal and marine biodiversity. Nevertheless, they are very sensitive and vulnerable to human impacts, which often result in a decrease of their biodiversity and degradation of their water quality. Considering recent efforts for ecological restoration of coastal lagoons, it appears appropriate to compare the social representations of users of the coastal lagoons and of inhabitants, with ecological diagnoses of biodiversity and water quality. The main question is whether there is congruence between water quality defined by environmental criteria on one hand and the social representations of these issues by lagoon users and local populations on the other hand? How can we explain the social representations of...