Identification des habitats de nourriceries de poissons à partir d'indicateurs faunistiques. Qualité de ces habitats pour les juvéniles de soles en estuaire de Seine

Numerous marine fish species spend some time, within their biological cycle, in the restricted and unstable habitats that are coastal and estuarine feeding grounds. These ecosystems are essential for the growth and survival of young fishes. Some recent studies, conducted in the framework of the "Seine Aval 1 and 2" programs and of other projects, demonstrated that the Seine estuary was home to large numbers of juveniles (Morin et al., 1997) but that this estuary was subjected to a strong anthropic pressure interfering with the feeding ground function it should normally play. There is, indeed, a paradox between the nutritive availabilities provided by the estuary and the ichtyic communities exploiting this resource (Mouny, 1998); and this observation is especially true for the juveniles of species of halieutic interest (Riou, 1999; Le Pape et al., 2000; Le Pape et al., accepted). The quality of a specific environment results from diverse interactions and, due to a lack of data over a long period during which the conditions evolved, cannot be measured directly. It can only be described through an inter-site comparison. The works carried out since 2000, in the framework of the "Seine Aval" programs, aimed to assess the quality of the Seine estuary as a fish feeding ground. (...)