The Bateguier pond on Sainte-Marguerite Island is the only body of salt water on the coast of the Alpes-Maritimes. The insularity of this lagoon gives it a significant heritage value and increases the fragility of its ecosystem, threatened with siltation and eutrophication. A priority habitat, the pond is home to an abundant population of sea rupella and a rich and diverse zoocenosis with many mollusks, remarkable avifauna of waders and migrating waders, as well as a nesting colony of common terns.