Lush thicket of Staghorn Coral in the Dry Tortugas National Park

Shallow water (less than ~150 m water depth) coral reefs are seafloor structures built from the calcium carbonate skeletons of marine organisms. Reefs buffer shorelines from waves, storm surges, and tsunamis and help to protect ~200 million of the world's coastal dwellers from flooding, erosion, property damage, and loss of life. Reefs support high levels of biodiversity; they are home to up to 25...