Notes |
Coral reefs are vital ecosystems, providing a source
of income, food and coastal protection for millions
of people; and recent studies have shown that coral
reef goods and services provide an annual net
benefit of US$30 billion to economies worldwide
(Cesar et al, 2003). Coral reefs are composed
mainly of reef-building corals: colonial animals
(polyps) that live symbiotically with the singlecelled
microalgae (zooxanthellae) in their body
tissue and secrete a calcium carbonate skeleton.
Coral reefs are formed by hundreds of thousands
of these polyps and are found in warm, shallow,
clear, low-nutrient tropical and sub-tropical waters,
with optimum temperatures of 25-29ºC, although
they exist in ranges from 18ºC (Florida) to 33ºC
(Persian Gulf) (Buddemeier and Wilkinson, 1994).
They are incredibly diverse, covering only 0.2% of
the ocean’s floor but containing 25% of its species
and they are often dubbed the ‘tropical rainforests
of the oceans’ (Roberts, 2003). |