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Ocean acidification killing oysters by inhibiting shell formation, study finds

Posted on June 14, 2013
A screen covered with oyster larvae, taken in 2007 at the Whiskey Creek Shellfish Hatchery near Netarts Bay, Ore. Credit: Lynn Ketchum, Oregon State University

A screen covered with oyster larvae, taken in 2007 at the Whiskey Creek Shellfish Hatchery near Netarts Bay, Ore. Credit: Lynn Ketchum, Oregon State University

For the past several years, the Pacific Northwest oyster industry has struggled with significant losses due to ocean acidification as oyster larvae encountered mortality rates sufficient to make production non-economically feasible.

Now a new study led by researchers at Oregon State University has documented why oysters appear so sensitive to increasing acidity. It isn’t necessarily a case of acidic water dissolving their shells, researchers say. Rather it is a case of water high in carbon dioxide altering shell formation rates, energy usage and, ultimately, the growth and survival of the young oysters.

Results of the study have been published online in the journal Geophysical Research Letters.

“From the time eggs are fertilized, Pacific oyster larvae will precipitate roughly 90 percent of their body weight as a calcium carbonate shell within 48 hours,” said George Waldbusser, an OSU marine ecologist and lead author on the study. “The young oysters rely solely on the energy they derive from the egg because they have not yet developed feeding organs.”

Under exposure to increasing carbon dioxide in acidified water, however, it becomes more energetically expensive for organisms to build shell. Adult oysters and other bivalves may grow slower when exposed to rising CO2 levels, other studies have shown. But larvae in the first two days of life do not have the luxury of delayed growth, the researchers say.

“They must build their first shell quickly on a limited amount of energy – and along with the shell comes the organ to capture external food more effectively,” said Waldbusser, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “It becomes a death race of sorts. Can the oyster build its shell quickly enough to allow its feeding mechanisms to develop before it runs out of energy from the egg?”

Read more at: Phys.org

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