Global ChangeIntersection of Nature and Culture

Ocean acidification negatively affects coral establishment

Monday, November 8th, 2010

When CO₂ from fossil fuels accumulates in the atmosphere, some of it dissolves into the oceans where it reacts with water to form a weak acid (H₂CO₃) —carbonic acid— that lowers seawater pH and makes it increasingly difficult for corals and other calcitic organisms to form their calcium carbonate (CaCO₃) skeletons.

A new study in the Proceedings of the National Academy of Sciences by Rebecca Albright and colleagues suggests that the negative effects of ocean acidification don’t stop with adult organisms.  The colonization and establishment of juvenile corals appear to be severely impacted.  They studied a common coral found in the Caribbean—Acropora palmata (elkhorn coral, which is not the same as the staghorn coral species pictured above).

A snapshot of their results:

• When corals were grown in seawater with elevated CO₂ to simulate mid- and late-century emissions trends, they found a 52% and 73% decline in coral settlement success, respectively.
• For corals that settled and started growing, they found that the mid- and late-century CO₂ levels reduced early growth by 39% and 50%, respectively.

This is potentially very bad news because if you shut down the capacity for new corals to establish, you reduce the ability of coral reef systems to persist in the face of disturbances like hurricanes, wave action, nutrient pollution, bleaching, and disease.

Rebecca Albright, Benjamin Mason, Margaret Miller, and Chris Langdon (2010). Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmata Proceedings of the National Academy of Sciences

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Photo credit:  One of my photos from the Great Barrier Reef.  Check out my entire collection at Flickr.