Impacts of environmental factors and shellfish practices on the Mont-St-Michel Bay ecosystem (France). A modelling study involving scientists, stakeholders and users of the bay

Philippe Cugier (1) , Caroline Struski (1) , Karine Grangere (1, 2) , Michel Blanchard (1) , Katia Frangoudes (3) , Thierry Robin (4) , José Pérez (5) , Rémi Mongruel (5) , Joseph Mazurie (6) , Patrick Le Mao (7) , Guy Fontenelle (8)

1 DYNECO - Unité Dynamiques des Écosystèmes Côtiers
2 PE2M - Physiologie et Ecophysiologie des Mollusques Marins
3 AMURE - Aménagement des Usages des Ressources et des Espaces marins et littoraux - Centre de droit et d'économie de la mer
4 Association Interdépartementale Manche
5 EM - Unité d'Economie Maritime
6 LERMPL - Laboratoire Environnement Ressources Morbihan Pays de Loire
7 CRESCO - Centre De Recherche et d'Enseignement sur les Systèmes Côtiers
8 ESE - Écologie et santé des écosystèmes

The macro-benthic communities of Mont-Saint-Michel Bay, located in the Norman-Breton Gulf (English Channel) along the French coast, are mainly dominated by filter-feeders which include cultivated species (oysters and mussels). The decline in shellfish farms production and the significant spreading of the invasive slipper-limpet Crepidula fornicata have conducted scientists and stakeholders to undertake a reflexion on the trophic balance between cultivated and wild (native or invasive non-native) filterfeeders. An ecological model of the bay was developed, coupling a 2D hydro-sedimentary model along with biological models for primary production and filter-feeder growth. The objectives of the project were first to provide indicators to stakeholders on the future evolution of the trophic resource taking in account environmental modifications and human pressure, and establish with them the scenarios to be developed by the model. To accomplish these objectives different focus groups were organised between scientists and stakeholders. Based on these exchanges scenarios on shellfish practices, watershed runoffs and Crepidula fornicata spreading, were investigated through numerical modeling tools. Then results of the models were presented to 6 stakeholders' focus groups and a social scientist has analysed first the interaction between scientists and stakeholders, second the perception of the models by the stakeholders and the ideas of stakeholders concerning the environmental problems face within the Bay.

Domaines: Sciences et techniques des pêches

Philippe Cugier, Caroline Struski, Karine Grangere, Michel Blanchard, Katia Frangoudes, et al.. Impacts of environmental factors and shellfish practices on the Mont-St-Michel Bay ecosystem (France). A modelling study involving scientists, stakeholders and users of the bay. International Congress on Environmental Modelling and Software, Jul 2010, Ottawa (US), Canada. pp.7. ⟨hal-00729540⟩