Effects a long terme du fonctionnement de l'usine maremotrice sur l'evolution du peuplement des sables fins vaseux de la Rance

Dynamic studies of the Abra alba-Melinna palmata muddy sand community from 1972 to 1982 show that after an initial recolonization until 1976 species richness and density exhibit a steady trend. Three groups of species and five main categories of population abundance evolution are deduced from qualitative and quantitative sampling. Rapid stabilization of abiotic factors occurs after the starting up of the tidal power dam in 1966 and the authors' evolutive scheme reflects both importance of hydrodynamic effects in the dispersion of benthic organisms and demographic strategies of main populations, especially annelids (80-90% of the community). Among the six annelid dominant species, four took part in the recolonization of the biotopa although they are able to live several years and possess a short pelagic stage in their larval development or none.