Coral reef to form fringing reefs, and can eventually grow become a barrier reef. Where the bottom is rising, fringing reefs can grow around the coast, but coral raised above sea level dies. If the land subsides slowly, the fringing reefs keep pace by growing upwards on a base of older, dead coral, forming a barrier reef enclosing a lagoon between the reef and the land. A barrier reef can encircle an island, and once the island sinks below sea level a roughly circular atoll of growing coral continues to keep up with the sea level, forming a central lagoon. Barrier reefs
Mesophotic coral reef Mesophotic coral reef A Mesophotic coral reef, from "meso" meaning middle and "photic" meaning light, is characterised by the presence of both light dependent coral and algae, and organisms that can be found in water with low light penetration. They normally grow between 30 to and up to in tropical and subtropical water. The most common species at the mesophotic level are corals, sponges and algae. The corals ranges can overlap with Deep-water coral but are distinguished by the presence of zooxanthellae and their requirement for light. They can also be thought of as part of shallow water coral ecosystems,