Coral reefs

What is a coral reef?

Coral reefs are natural structures composed mainly of coral. They are among the most complex and diverse of all marine ecosystems, are rich in biodiversity and form generally in shallow waters. They procure ecological niches for numerous species who feed and shelter in the coral.

Where are they located?

Although some coral species live in cold and deep waters and in temperate zones, most reef systems are found in the light zone within the first 20 metres of the inter tropical zone where conditions are more to their advantage. The largest reef systems in the world are located in Australia, New Caledonia and Belize and they form huge structures at the ocean's surface which are visible from space.

Why is it important to study them?

During the 20^th century, the increase in carbon dioxide in the atmosphere resulted in a 17 cm increase in sea level and a 0.74 °C increase in its temperature. This in turn modifies the chemistry of the oceans which in the future could weaken the structure of coral and reduce the growth of reefs mainly in higher latitudes. Even in warm waters, coral reefs are vulnerable to rapid changes in the climate.

They are thus excellent recorders of past variations in sea level and environmental parameters for the last tens of thousands of years. Research based on archives represents essential data for climate and sea level evolution models for the near future.