An evaluation of the energy transfer between zoobenthos and water birds in the Mont-Saint-Michel bay was carried out from October 2003 until September 2004. Global consumption by waders is similar to that estimated on data collected 20 years ago, in spite of strong variations in seasonal occurrence and species composition of shorebirds populations in the bay. Total consumption (including gulls and predatory anseriformes) is about 2,15 g ash free dry weight/m2 /year, a very low figured if compared to results from the Wadden Sea. These two results seems to confirm the initial findings from the PNEC research program in the Mont-Saint-Michel bay: the bay is an oligotrophic system (oceanic type) presenting a strong functional inertness in the mid and long term, because little subjected to the effects contributing coastal rivers. The situation is very different in many other coastal areas, especially in the Wadden Sea which is an eutrophic system, with strong between year variations, where the , often very high primary and secondary production, are reinforced by nutrients flows induced by eutrophic freshwaters streams.