Madagascar Reefs May Hold Keys to Rebirth, Despite Bleaching

October 17, 2006

Though blighted, coral reefs discovered off Madagascar may provide the seeds of recovery for marine life devastated by rising sea temperatures, researchers say.

A survey of coral reefs along the African island nation's remote southwest coast has revealed massive damage from coral bleaching—the loss of algae that live within corals and provide them with both food and color (Madagascar map, facts, and music).

Some areas were found to have lost up to 99 percent of their coral cover. But researchers also discovered pockets of bleaching-resistant corals. The scientists say these animals could help revitalize dying reefs.

"To find these little foci of resistance is extremely rare and is of massive conservation importance," zoologist Alasdair Harris said.

Global Warming

Harris is research director for the London-based marine conservation group Blue Ventures. The organization led the survey in partnership with the Bronx, New York-based Wildlife Conservation Society.

He says the survey shows the importance of locating and protecting healthy coral ecosystems.

"As climate change poses an increasing threat to our marine habitats, these resilient areas could hold the key to ensuring the continued existence of coral reefs around the world and the marine species that rely on them for survival," he added.

The team found that, as in other regions of the Indian Ocean, coral reefs are dying off southwest Madagascar. (Related: "Global Warming Has Devastating Effect on Coral Reefs, Study Shows" [May 16, 2006].)

Bleaching—so called because the corals turn white—affected 75 percent of coral reefs around the world in 1998, according to the United Nations Environment Programme. The Indian Ocean was badly hit in 2000 too.

"There has been mass mortality relating to hot sea surface water," Harris said.

Madagascar, the world's fourth largest island, is renowned for its wealth of unique plants and land animals, including lemurs, fossas, and giant jumping rats. Less known is the diversity of marine life around its shores. (Related: "Coral Trove Found Off Madagascar" [May 15, 2002].)



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