The Red Sea and its Coral reefs

Coral reefs need warm, clear waters and have little tolerance for sedimentation or influxes of fresh water. Since it's sunny all year round and virtually no rivers flow into the Red Sea, it's perfect for coral growth.

Corals cannot survive below 18 degrees C. With water temperatures well above this minimum, reefs of the Red Sea also benefit from its still, protected waters: because there's very little sediment, light penetrates a long way down.

Indeed, large storms, hurricanes and typhoons are a major source of coral mortality. The Red Sea, on the other hand, is almost always placid - its warm, quiet waters make it an ideal coral habitat.

How do reefs form?
Reefs are composed of limestone topped by a layer of living organisms, which add a few millimetres more limestone to the ancestral reef each year. Coral polyps may not dominate the biomass of the community, but the existence of other organisms is based on the ability of corals to build a massive, wave-resistant structure. The communal efforts of these small organisms has produced many reefs worldwide, the biggest of which is the Great Barrier Reef, a 2000 km complex of reefs and islands stretching along much of the east coast of Australia.

Charles Darwin was the first person to make a systematic study of coral reefs and his classification of reef types is still in use today. The three main types are fringing reefs, barrier reefs and atolls. Fringing reefs are found along landmasses where adequate currents provide the proper temperature. Because of the arid climate, the fringing reefs of the Red Sea are some of the best developed in the world and are found along virtually all of its shores.