Coral reef A fringing reef forms around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the fringing reef becomes a barrier reef and ultimately an atoll reef. Darwin predicted that underneath each lagoon would be a bedrock base, the remains of the original volcano. Subsequent research supported this hypothesis. Darwin's theory followed from his understanding that coral polyps thrive in the tropics where the water is agitated, but can only live within a limited depth range, starting just below low tide. Where the level of the underlying earth allows, the corals grow around the coast
Coral reef protection experienced quick-moving currents that efficiently flushed away sediment, protecting the reef, while the other was subjected to currents and wave conditions that allowed sediment to be continuously re-suspended in the water, starving the reef of light. The vast biodiversity of coral reefs consequently create an abundant fishing area for locals. This leads to overfishing of reef herbivore organisms which makes the coral reefs more vulnerable and unable to recover from large environmental disturbances. Unfortunately, most marine ecologists expect future oceans to be more overfished than now. It is difficult to create a substantial plan for the protection of coral reefs