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Off Western Australia, temperature rules the reefs

Tim Cooper coring a massive Porites coral at the Rowley Shoals in Western Australia.
[Image courtesy of Timothy Fraser Cooper]

Australia's Great Barrier Reef has been in decline for years. Its crumbling conditions have caused many researchers to predict that higher levels of carbon dioxide in the world's oceans would only harm the coral further. But, new research is suggesting that a more acidic ocean—due to increased carbon dioxide levels—would not actually affect coral reefs as much as the sea's temperature.

Ignoring the Great Barrier Reef, Timothy Cooper and his colleagues studied Porites, a type of stony coral, off the coast of Western Australia—the other side of the island continent—and found that corals there have been thriving throughout the 20th Century. According to the researchers, temperature has much more control over coral growth in that part of the Indian Ocean than the pH of the water does.

Cooper and his colleagues looked at large coral reef structures that span 11 full degrees of latitude on a map and discovered that coral growth has increased significantly during the past 110 years there, especially at higher latitudes. They could find no evidence of large-scale declines, like that seen near the Great Barrier Reef.

But, the researchers still warn that increasing ocean temperatures may lead to such declines in the future. According to Cooper and his team, rising sea surface temperatures don't appear to affect coral growth up to a certain point; but then something called "coral bleaching" begins to slow the reef-builders down.