Coral reef 'glue' may not stick under climate change

From an article by Jessica Marshall on Discovery News:

July 29, 2008 -- The cement that buttresses coral reefs, giving them the strength to withstand crashing waves and other onslaughts, may stop forming as oceans acidify under increased carbon dioxide in the atmosphere.

Researchers have already predicted that a more acidic ocean will make it more difficult for corals to build their calcium carbonate skeletons. The new finding suggests that the reef's broader structure may also suffer because a lower pH reduces the formation of the reef's cement binder. The binder is made from calcium carbonate that precipitates out of ocean water when it rushes through the pores of coral skeletons.

"Until now, we've mostly addressed acidification in terms of what it does to the living organism," said study author Joan Kleypas of the National Center for Atmospheric Research in Boulder, Colo.

"Here we're finding that the reef structure itself can certainly feel the effect of ocean acidification, even if the biology somehow finds a way to cope with acidification. This is mainly an inorganic process, so we're looking at something that will happen regardless of what the biology does."

The researchers made their findings by comparing places around the world where CO2 levels in the ocean vary naturally.