Shallow coastal lakes still temporarily connected to the sea that have been formed as a result of the separation of shallow inlets and bays (1160) from the sea. The salinity of the lagoons depends on the exchange of water with the sea on the one hand and the amount of precipitation and the inflow of fresh water on the other.
Compared to the estuaries of rivers (1130), less fresh water ends up here. Coastal lagoons are valued primarily for their peloid reserves and abundant birdlife. The water here is rich in chlorides and sulphates. The thick bottom mud is often covered by charophytes, and the biota is mostly poor. Phytoplankton is rich in species, but with low biomass (probably due to food competition with charophytes); they contain saline-loving algae, especially diatoms.
In Estonia, coastal lagoons are widespread mainly in Western Estonia and its islands: the Sutlepa Sea in Lääne County, Käomardi Bay in Pärnu County, Oessaare and Mullutu-Suurlaht in Saare County, small lagoons on the islands of the Väinameri Sea, etc.
Includes the habitat type 6116 (halotrophic waterbody site type) according to Paal.