Study links raised carbon dioxide levels to oyster die-offs

Oyster hatcheries along the Washington and Oregon coastlines began experiencing calamitous die-offs beginning in 2006. Scientists suspected they were because of increased carbon dioxide levels in the air that were causing ocean acidification. That theory has now proved out, according to a study just published by the journal Limnology and Oceanography.

Researchers studied oysters at Oregon’s Whiskey Creek Hatchery in 2009 after the hatchery reported that oyster production had declined by as much as 80 percent in recent years. The scientists paid close attention to the seawater that had bathed the oysters. Oceans absorb a significant portion of carbon dioxide in the air and when they do so a chemical process takes place called acidification. Laboratory studies have already shown that elevated carbon dioxide changes the pH and reduces the availability of calcium carbonate in the seawater. And calcium carbonate minerals are the material that sea creatures like oysters and corals use for building shells and skeletons.

The study breaks new ground, according to its authors, because this is the first time these theories on the impact of ocean acidification that were tested in laboratories were verified on an actual commercial shellfish farm with ambient ocean waters. The findings linked the production failures of the farms to the carbon dioxide levels in the seawater in which the larval oysters were spawned and spent the first 24 hours of their lives. That is the time when oysters start to develop their first shells.

Leslie Kaufmann, The New York Times, 12 April 2012. Full article.


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