Researchers at Oregon State University have definitively linked an increase in ocean acidification to the collapse of oyster seed production at a commercial oyster hatchery in Oregon, where larval growth had declined to a level considered by the owners to be “non-economically viable.”

A study published in the journal Limnology and Oceanography found that elevated seawater carbon dioxide (CO2) levels, resulting in more corrosive ocean water, inhibited the larval oysters from developing shells and growing at a pace that would make commercial production cost-effective.

As atmospheric CO2 levels continue to rise, the scientists say, this may serve as the proverbial canary in the coal mine for other ocean acidification impacts on shellfish.

“This is one of the first times that we have been able to show how ocean acidification affects oyster larval development at a critical life stage,” said Burke Hales, an OSU chemical oceanographer and co-author on the study. “The predicted rise of atmospheric CO2 in the next two to three decades may push oyster larval growth past the break-even point in terms of production.”

The owners of Whiskey Creek Shellfish Hatchery at Oregon’s Netarts Bay began experiencing a decline in oyster seed production several years ago, and looked at potential causes including low oxygen and pathogenic bacteria. Alan Barton, who works at the hatchery and is an author on the journal article, was able to eliminate those potential causes and shifted his focus to acidification.

Barton sent samples to OSU and the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory for analysis. Their ensuing study clearly linked the production failures to the CO2 levels in the water in which the larval oysters are spawned and spend the first 24 hours of their lives, the critical time when they develop from fertilized eggs to swimming larvae, and build their initial shells.

“The early growth stage for oysters is particularly sensitive to the carbonate chemistry of the water,” said George Waldbusser, a benthic ecologist in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “As the water becomes more acidified, it affects the formation of calcium carbonate, the mineral of which the shell material consists. As the CO2 goes up, the mineral stability goes down, ultimately leading to reduced growth or mortality.”

Oregon Sea Grant, which has long supported research into shellfish propagation and health,  is currently  investing $175,000 in further research by Waldbrusser, Hales and OSU shellfish scientist Chris Langdon to develop Web-based tools shellfish growers, resource managers and others can use to better understand whether acidification is threatening specific shellfish stocks.

• Read the full OSU news release on the new research findings
• News coverage: New York Times Green blog;    Seattle Times; Oregon Public Broadcasting/NPR
• Read more about Waldbusser’s current Sea Grant-funded project.

Oregon Sea Grant video – NOAA’s Richard Feely explains the basics of ocean acidification:

(Part 1 of 3; view  part 2 and part 3 on our Website.)