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Coral bleaching

Page - August 23, 2007
Coral bleaching is a condition that can seriously damage and kill entire coral reefs. Corals contain microscopic algae called zooxanthellae that provide the coral with food and give them their vibrant colours. Rising ocean temperatures cause corals to become stressed, and they expel the zooxanthellae and turn white or "bleach". If zooxanthellae do not return to the coral’s tissue, the coral will die.

Bleached coral, Great Barrier Reef. Effects of climate change.

As little as a 1° Celsius (1.8°F) increase in temperature above thesummer maximum can cause corals to bleach. Tropical seatemperatures have increased by 1° Celsius over the past 100 years andare predicted to continue rising.

An example of this problem is Australia's world famous Great BarrierReef, which lies off the state of Queensland. At around 2,000kilometres (1,243 miles) long it is the world's largest reef.

But in 2002 the reef experienced its worst ever case of coralbleaching, with over 60 percent of the reef being affected. Unlessprojected levels of climate change are slowed, much of the reef will bedead in decades. Deprived of their living homes, hundreds of speciesrelying on the reef will also die out.