Long-term dynamics of three benthic Ampelisca (Crustacea-Amphipoda) populations from the Bay of Morlaix (western English Channel) related to their disappearance after the ‘Amoco Cadiz’ oil spill

Many studies have dealt with the effects of the ‘Amoco Cadiz’ wreck. In particular, they describe the influence of the oil spill on the benthic populations dynamics off northern Brittany coasts (western English Channel). Several mechanisms have been proposed to explain how communities have recolonised the area during these last 20 yr. In this paper, we focus on the dynamics of the Pierre Noire Ampelisca populations which constitute the dominant part of the total fine sand Abra alba community. We propose a discrete population dynamics model that takes into account the sea temperature, the amount of pollutant and competition. The model permits the simulation of long term changes in abundance for each of the more abundant Ampelisca species. It provides a tool for testing assumptions and for understanding the different processes occurring during recolonisation.