The Gerrico Project is jointly managed by Ifremer and the University of Nantes, and focuses on the Bay of Bourgneuf. Located in the South of the Loire estuary on the French Atlantic coast, this bay is extensively utilised for oyster farming (13,000 tons annually) and is characterised by many interesting habitats such as seagrass beds and honeycomb worm reefs. The Bay of Bourgneuf has been faced with a number of problems in recent years such as oyster growth and edible quality, survival rates, the maintenance of water quality and biodiversity, and the sustainability of oyster farming and related activities. The originality of Gerrico lies in its objective to develop methods capable of taking the entire area into account, from the watersheds down to the marshes and the coastal zone, using a chain of coupled models to integrate the different activities by combining physical modelling (sedimentology, hydrodynamics), biological modelling (growth of the algal biomass, oyster growth), and economic modelling (management of oyster rearing parks at the scale of the production basin or the shellfish farming business as a whole). The common issue driving this approach is water quality, on which any optimisation of coastal activities depends. Several scenarios at different spatial and temporal scales: increasing nutrients; oyster growth variability between farming sites, impact of trophic competitors (slipper limpets, wild oysters), or water carrying capacity assessment, for example, have been implemented in order to simulate the biological and socio-economic consequences of different types of management. The objective is to establish a dynamic tool that will provide a reliable platform for integrated management of the coastal area.