recifes

Recifes, or reefs, are underwater structures formed by living organisms, principally corals, and by geological processes that create stable habitat features. The term most often refers to coral reefs, which are built by colonies of reef-building corals and a diverse associated biota. Reefs occur in shallow, sunlit, warm waters and are among the most productive and biodiverse ecosystems in the world, supporting fisheries, tourism, and coastal protection.

Coral reefs form through the accumulation of calcium carbonate skeletons secreted by reef-building corals, aided by symbiotic algae. They require warm temperatures, clear water, adequate light, and limited sediment. Reefs commonly develop as fringing reefs along shorelines, expand into barrier reefs with a peripheral lagoon, or form atolls around submerged volcanoes. Non-biogenic reefs arise from geological and mineral processes that create rocky or carbonate structures.

Coral reefs provide habitat for countless species, support fisheries and tourism economies, and reduce wave energy to help protect coastlines. They are highly productive despite often small physical footprint, with complex structures offering refuge, feeding grounds, and spawning sites. The health of reefs is closely linked to water quality, temperature regimes, and the broader tropical marine climate.

Global threats include warming oceans, which cause coral bleaching, and ocean acidification, which weakens skeleton formation. Local pressures such as overfishing, destructive fishing practices, pollution, sedimentation, and coastal development degrade reef communities. Conservation approaches emphasize marine protected areas, sustainable tourism, habitat restoration, water quality management, and policies to mitigate climate change and reduce land-derived runoff.

Reefs are concentrated in tropical and subtropical seas, with large systems in the Caribbean, the western Indian Ocean, the Coral Triangle, and the Pacific. Notable examples include the Great Barrier Reef, the Mesoamerican Barrier Reef, and Red Sea and Indonesian reefs, which illustrate the diversity of forms and ecological significance of reef ecosystems.