From: Editor, ENN
Published November 5, 2014 03:10 PM

Can ocean acidification have a positive effect on corals?

A majority of recent reports highlights the negative effects of warmer water temperatures on corals. Because of increasing numbers of bleaching events, where corals become white resulting from a loss of their symbiotic algae, corals become stressed and can starve to death if the condition is prolonged.

However, researchers from Northeastern University's Marine Science Center and the University of Chapel Hill have found some slightly positive effects that moderate ocean acidification and warming can have on coral.

According to the research, the growth rate of one reef-building coral actually improved with moderate ocean acidification.

Justin Ries, an associate professor at Northeastern and one of the paper’s co-authors, focuses his research on the biological impacts of rising atmospheric carbon dioxide levels to organisms that would be greatly affected by ocean acidification. These organisms include those that build calcium carbonate shells and skeletons, such as coral, snails, and clams, which, unfortunately are already near the point of dissolving in some parts of the ocean.

However, the researchers have discovered a positive response to moderately elevated carbon dioxide. This can be attributed to the fertilization of photosynthesis within the coral’s algal symbionts, which may provide the coral with more energy for calcification even though the seawater is more acidic.

“The study showed that this species of coral (Sideratrea siderea) exhibited a peaked or parabolic response to both warming and acidification, that is, moderate acidification and warming actually enhanced coral calcification, with only extreme warming and acidification negatively impacting the corals,” Ries said. “This was surprising given that most studies have shown that corals exhibit a more negative response to even moderate acidification.”

According to projects from the Intergovernmental Panel on Climate Change, this study indicates that by the end of the century, ocean warming is likely to threaten this coral species more than acidification.

The work is published in the journal Proceedings of the Royal Society B: Biological Sciences.

Read more at Northeastern University.

Coral image via Shutterstock.

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