The habitat of coastal lagoons has a special regime in the Danube's Delta's Biosphere Reserve. In the Danube's Delta, the habitat of coastal lagoons is represented by the Razim-Sinoe complex.

At first this complex was a simple open lagoon. After the artificial closure of the area's communication with the sea, there were made attempts to modify the saltwater/freshwater ratio, in order to use the resulted water for irrigations. As a result, in time, the Razim-Sinoe complex became a habitat for freshwater loving species.

The Razim-Sinoe complex includes habitats with spread waters, common reed areas and adjacent rocky areas. The Razim-Sinoe complex is a combination of habitats for many species of plants, birds and mammals.
Besides the lagoon, the Razim-Sinoe complex has other adjacent areas, which are strictly protected.

The authorities are trying to repopulate the area with zander larvae, in order to keep the silver carp population from the area under control.