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CORVALLIS, Ore. - Researchers at Oregon State University will begin delving into the impacts of ocean acidification on shellfish, launching two National Science Foundation-funded projects that will explore the marine organisms' physiological responses to corrosive ocean water.

In one study, OSU scientists are seeking to determine the threshold at which oysters, clams and mussels - including those that are commercially important - become adversely affected by acidification. Principal investigator George Waldbusser of OSU's College of Oceanic and Atmospheric Sciences and his colleagues also will explore the mechanisms through which those impacts occur.

"We'll be developing a novel experimental approach to tease apart just what component of acidification is actually affecting the organism," Waldbusser said. "For example, decreased pH may affect the internal acid-base balance of an organism, but the correlated decrease in calcium carbonate saturation state may also alter the stability of their mineral shells.

"Scientists know very little, to date, about specific modes of action triggered by acidification," he added.

Waldbusser received a four-year grant of nearly $2 million from NSF to lead the project. He will work with Burke Hales and Brian Haley from the university's College of Oceanic and Atmospheric Sciences, and Chris Langdon, who directs the Molluscan Broodstock Program at OSU's Hatfield Marine Science Center in Newport.

They will develop their experimental system at the Hatfield Marine Science Center, which has a large seawater system that makes such research possible.

OSU received a second three-year, $2 million grant from NSF to lead a seven-institution project to monitor ocean chemistry in the California Current System and look at how two marine species - sea urchins and mussels - respond in the wild to different ocean chemistry.

This project is being coordinated through the Partnership for Interdisciplinary Studies of Coastal Oceans, or PISCO, an OSU-based marine research consortium. Principal investigator Bruce Menge and colleagues from multiple institutions will study urchins and mussels at two sites in Oregon and six sites in California, taking advantage of the differing levels of acidification along the West Coast.

The researchers theorize that these organisms have adapted over time to variations in the ocean chemistry, but the increase in carbon dioxide may be pushing their limit.

"They already may be close to their acclimatization or adaptational capacity," Menge pointed out, "and thus may have limited ability to respond to additional increases in CO2. For the first time, we will be able to examine the genetics and ecology of these key organisms to see how populations that span over a thousand miles of coastline are coping with changes in ocean chemistry."

Increasing ocean acidification is a major global concern. Previous OSU research, led by Hales, found that seawater being upwelled from the deep ocean may have last been exposed to the atmosphere some 50 years ago and that its already-high levels of carbon dioxide portend more corrosive oceans in the future.

Their ongoing research also found that the upwelled water is influencing Oregon estuaries, where concern about acidic water has prompted oyster hatcheries to alter their protocols. For example, the Whiskey Creek Hatchery is now drawing water into its tanks during relaxed upwelling periods, or in the afternoon, when acidity levels are lower due to increased photosynthesis.