Florida Reef

The Florida Reef is the only living coral barrier reef in the continental United States, a band of coral about 350 miles long that curves from the Dry Tortugas past the Florida Keys and north along the Atlantic coast. It lies several miles offshore, parallel to the islands, and it shelters them from the open ocean. Molasses Reef, off Key Largo, is one of its best known and most visited sections. The reef is built by stony corals, animals that lay down limestone skeletons over thousands of years, and the upper Keys themselves are made of ancient reef rock. Elkhorn and staghorn corals once formed thick stands in the shallow reef crest, but disease and warming water since the 1970s killed most of them, and the marine heat wave of 2023 left both species functionally extinct on the Florida reef. Molasses Reef shows the damage people can do in a moment. In 1984 the freighter Wellwood ran aground on it and crushed a large area of living reef, and the grounding became a landmark case in how the federal government recovers the cost of reef damage. The Florida Keys National Marine Sanctuary protects it, beside John Pennekamp Coral Reef State Park, established in 1963 as the first undersea park in the United States. The reef has suffered repeated coral bleaching in marine heat waves, and coral nurseries across the Keys are growing corals to replant it.