lagunas

Lagunas are shallow bodies of water that are partially or fully separated from a larger body, typically the ocean, by a barrier such as a sandbar, spit, barrier island, or coral reef. The water in lagunas is often brackish, blending sea salt with freshwater from rivers or groundwater, but some lagunas are entirely freshwater or highly saline, depending on exchange with the open sea and evaporation in arid regions.

Coastal lagoons are the most common, forming behind coastal barriers where sediment accumulates to create a sheltered basin. They exchange water with the sea through one or more inlets, and salinity can vary with tides and rainfall. Inland lagunas or crater lagunas form in volcanic craters or tectonically formed basins and are usually freshwater; some become saline if connected to seawater by channels. Lagoons connected to coral reefs create real reef lagoons that host diverse marine life. The extent of mixing with seawater, the size of the inlet(s), and the climate all influence nutrient dynamics and salinity.

Ecology in lagunas is typically productive due to nutrient inputs and sheltered conditions. Seagrass beds, algae, and invertebrates support a range of fish and crustaceans, while birds often rely on lagoon margins for feeding. Lagunas frequently serve as nurseries for fish and as important stopover sites for migratory birds.

Humans use lagunas for fishing, aquaculture, salt production, tourism, and, in some regions, freshwater supply. They face threats from land development, dredging, pollution, eutrophication, invasive species, and climate change, which can alter salinity, sedimentation, and connectivity to the sea. Protection and restoration efforts aim to preserve their ecological function and livelihoods, often through protected areas and sustainable management practices.