Manmade carbon emissions and the seasonal upwelling of naturally carbon-rich waters are driving up the acidity of the shallow ocean just off the West Coast, a team of researchers from Oregon and elsewhere has found, posing a threat to shellfish, sea urchins and smaller shell-forming creatures that serve as food for young salmon.
Their study, published online today in the journal Science Express, for the first time documents high acidity in the shallow nearshore waters of the West Coast’s fruitful continental shelf, the researchers said. It expands on global research into ocean acidification, which has tied increasing acidity levels to the ocean’s absorption of manmade carbon dioxide emissions and warned that it could decimate coral reefs.
The acidity the researchers documented along the coast from Canada to Oregon to Mexico last spring is at levels that scientists expected to see in 50 to 100 years, the researchers said, and is likely high in nearshore waters worldwide that get seasonal upwelling of deeper waters.
Those deeper waters were last at the surface 50 years ago but show clear signs of higher carbon content and acidity because of manmade emissions, the researchers said. Given steep increases in carbon dioxide emissions since the 1950s, the long-term cycle means spring and summer acidity levels are likely to rise for another 50 years off the West Coast no matter what steps are taken to reduce carbon emissions now.
The research team used an Oregon State University boat and included researchers from Oregon, Mexico, Canada and the U.S. National Oceanic and Atmospheric Administration. Burke Hales, an OSU professor of chemical oceanography and a member of the research team, said the year to year changes in acidity are small and more study needs to be done on their biological effects. Some organisms could adjust to higher acidity levels.
But West Coast waters are naturally up to the brink of acidity levels hospitable to many shellfish and other ocean organisms. And the researchers documented acidified water within 20 miles of the coast.
“The natural system has put us close to the edge,” Hales said. Manmade emissions “are starting to push us over.”
Scott Learn , The Oregonian, 22 May 2008. Article.
