lagune

Lagune is a term used in several languages to describe a shallow coastal or near-coastal water body that is partially enclosed by barrier formations such as sandbars, barrier islands, or coral reefs, and separated from the open sea by a narrow opening. In English, the corresponding term is lagoon. Lagunes can also form inland behind barriers or within enclosed basins.

Formation and hydrology

Lagunes form when sediments build up to create a barrier that limits exchange with the adjacent sea. Tidal action, longshore drift, and wave-driven sediment transport contribute to the barrier’s growth. The degree of water exchange through the inlet controls salinity, which can range from brackish to nearly freshwater in some cases. Water residence times vary widely, influencing nutrient dynamics and productivity.

Ecology and habitats

Lagunes are typically productive ecosystems. They often host seagrass beds, salt or freshwater marshes, and mangroves along their margins. The sheltered waters provide nursery habitats for many fish and crustaceans and attract wading birds and waterfowl. The ecological character of a lagune is shaped by salinity, sediment supply, nutrient input, and the surrounding land use.

Types and examples

Coastal lagoons, or barrier-lagoon systems, are common along many coastlines. Inland lagoons form behind natural barriers or in depressions. Notable examples include large coastal lagunes in tropical regions and the Venetian Lagoon in Italy, where urban development overlaps with a historically dynamic lagoon system.

Threats and management

Lagunes face threats from eutrophication, pollution, sedimentation, dredging, and sea-level rise. Management often focuses on integrated coastal zone planning, habitat protection, and efforts to maintain or restore natural hydrology and water quality.