Bodega Bay scientists weigh impact of ocean acid levels on shellfish

  • Annaliese Hettinger,29, Bodega Marine Lab PhD candidate, gathers native oysters from a Tomales Bay oyster farm for a study at the Bodega Bay lab looking at the effects of increased ocean acidity on shellfish Wednesday, September 2.

The danger from increasing levels of acid in the ocean, which could devastate California's shellfish industry, is under investigation by Bodega Bay scientists.

It is painstaking work that requires the team to wade through knee-deep mud at Tomales Bay to collect native Olympic oysters and then raise their young in salt-water tanks under conditions that mimic climate change.

"Very little is known about how ocean acidification is unfolding, other than it is," said Susan Williams, director of the Bodega Marine Laboratory, which is part of UC Davis. "We are already seeing dramatic effects."

The evidence is seen in the dissolving shells of some mollusks and disappearing mussel beds. And researchers, with the backing of more than $4 million in University of California and federal funds, are trying to identify the long-term consequences of the ocean's changing chemistry.

So far, the research has been limited to Olympia oysters, a native species that grows in the wild. But the conditions apply to other shellfish, such as abalone, clams, mussels and sea urchins.

Oysters are "the canary in the coal mine," said Brian Gaylord, a marine lab biologist.

The amount of carbon dioxide in the atmosphere has increased 30 percent in the past 150 years and, with climate change, is predicted to double in the next 100 years.

"What happens in the ocean mirrors what happens in the atmosphere," said Tessa Hill, an oceanographer and chemist at the lab.

The ocean absorbs the carbon dioxide and that changes the chemistry of the water to make it more acidic, which inhibits the ability of shellfish to form shells, Hill said.

The research involves collecting oysters in Tomales Bay, letting them spawn and then putting the larvae into conditions that introduce differing levels of carbon dioxide into the water. The juvenile oysters are then measured and studied.

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