Reefs Find Shelter from the Heat

December 4, 2007

A WCS study finds that the prospects of coral reefs in the age of climate change have improved. Reefs living in sites with variable temperatures are better able to survive warm water.

It’s not stability they need, but variation, according to a new study on the ability of coral reefs to endure in the age of climate change. As ocean temperatures rise, corals have the best chances of survival in “tough love” seas with wide-ranging seasonal temperatures. Conversely, reefs living in environments with stable but higher temperatures are more susceptible to fatal bleaching.

“This finding is a ray of hope in a growing sea of coral bleaching events and threatened marine wildlife,” said Dr. Tim McClanahan, lead author of the study and a senior scientist with the Wildlife Conservation Society’s Coral Reef Programs. “With rising surface temperatures threatening reef systems globally, these sites serve as high diversity refuges for corals trying to survive.”

Coral reefs are composed of tiny creatures that live in colonies in mostly tropical and subtropical waters. The beneficial algae that live within the tissues of corals give them their stunning colors. During prolonged, unusually high surface temperatures, many coral species discharge the algae and “bleach,” leaving the reefs white and sickly.

The WCS study, published in the latest edition of the journal Ecological Monographs, examined temperature variations and coral bleaching events off the coast of East Africa between 1998 and 2005. The researchers found that the coral reefs in sites with the most temperature variation were located in the “shadow” of islands, protected from the oceanic currents that reduce temperature variations in reef ecosystems. The authors of the study posited that because corals in these locations are better adapted to environmental variation, they are more likely to survive dramatic increases in temperature.

“The findings are encouraging in the fact that at least some corals and reef locations will survive the warmer surface temperatures to come,” added McClanahan. “They also show us where we should direct our conservation efforts the most.”

WCS works to protect coral reefs throughout the world, with projects on reef systems in Belize, Indonesia, Papua New Guinea, Fiji, and Madagascar. All of these nations are island environments that may foster the health of reefs across the global warming crisis.

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