Oyster shells are an antacid to the oceans

How does the Chesapeake Bay spell relief? O-Y-S-T-E-R-S, a new study finds.

Like ocean waters around the world, the Chesapeake has become more and more acidic as a result of rising levels of carbon dioxide in the atmosphere. Now, by studying oyster populations in relation to acidity levels, a team of researchers has concluded that oysters — particularly their shells — can play a significant role in reducing that acidity.

“Oyster shells are made out of calcium carbonate, so they’re sort of like an antacid pill,” said George Waldbusser, an assistant professor of earth, ocean and atmospheric sciences at Oregon State and an author of the study, which appears in the journal Ecology. “In an undisturbed oyster reef, healthy oysters are generating a lot of biodeposits,” a genteel term for excrement, “which helps generate CO2 to help break down those shells, which helps to regenerate the alkalinity back into the environment.”

Since the Industrial Revolution, ocean acidity has increased by about 30 percent, researchers say, and it is on track to double by 2100. Among the dangers of highly acidic waters are damage to fish larvae and corrosion of mollusk shells, which means the oysters in this case are helping themselves. “It creates a positive feedback loop,” Dr. Waldbusser said.

Programs to replenish Chesapeake oyster reefs — mainly to filter out pollution and combat overharvesting — date to the 1960s. But the researchers say larger, older oysters should be introduced at a faster rate to fend off the rising acidity.

Douglas Quenqua, The New York Times, 20 May 2013. Article.

1 Response to “Oyster shells are an antacid to the oceans”

  1. 1 Lina Hansson 29 May 2013 at 07:51

    Note that the terminology used in this article is misleading. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7″. Despite the process of ocean acidification (the acidity of seawater has increased 26% since preindustrial time), the oceans are alkaline (pH higher than 7) and will not become acidic in the foreseeable future. Hence, the words “acid” or “acidic” should not be used when referring to seawater. Note that there are few exceptions, seawater can be acidic in the immediate vicinity of CO2 vents or in purposeful perturbation experiments.

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Ocean acidification in the IPCC AR5 WG II

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