Water Depth: less than 25m but not exposed to air;
Light: for photosynthesis;
Clean, clear water, sediment free,
Well oxygenated water produced by strong wave action;
Global Distribution Global distribution: Tropical seas between Tropics of Cancer and Capricorn. Offshore, on eastern and western continental and island margins. 92% of total found in Indo-Pacific region.
Type of Reef
Fringing reef – reef that is directly attached to a shore or borders it with an intervening shallow channel or lagoon.
Barrier reef – reef separated from a mainland or island shore by a deep lagoon ; see Great Barrier Reef .
Atoll reef – a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island; see atoll .
Charles Darwin postulated that fringing reef, barrier reef and atoll development happened through geological time as a result of continued reef growth and volcanic subsidence.
James Dwight Dana (a geologist) provided evidence top support Darwin's theory of uplift and subsidence.
Reginald Daly (20 th Century)
An island emerges from the surface of the sea.
Sea levels drop significantly during an Ice Age.
Horizontal terraces and ledges are cut by erosion during the period of low sea level.
As the Ice Age ends the sea level rises.
Coral reef growth subsequently takes place on the newly created submerged platforms.
Daly in Diagrams
The 3D Theory of Coral Development The modern explanation of coral reef development should correctly be called the Darwin/Dana/Daly Theory (The 3D Theory!) of Coral Reef Formation since only the works of these three men taken together can fully explain the characteristics observed on atolls today.
Threats to Coral Reefs
The Impacts Coral Bleaching Damaged Coral
Coral Reef Management
What can be done to protect the worlds coral reefs?