The Site comprises five Mediterranean lagoons: Bages-Sigean, Ayrolle, Campignol, Gruissan and La Palme. Though fed by freshwater, they are connected to the sea, and the inlets of Ayrolle and La Palme are the last naturally functioning connections to the sea on the French Mediterranean coast. Large areas of lagoon vegetation and varying salinity characterize the ponds and create diverse habitats such as reedbeds, rush, salt marshes, salt steppes and fixed dunes. The proximity of wet and very dry habitats, especially on the limestone islets, is also a particularity of the Site. These diverse habitats have high value as wintering and breeding sites for birds as well as staging and feeding sites for migrating species. The Site is potentially threatened by degradation of the water quality and of water circulation in the lagoons, increasing human impacts, and recession of reedbeds. Tourist development and especially water sport activities threaten the Site’s highly sensitive ecosystems such as the dunes and salt steppes.