Experiment looks for shell fishing’s future in changing ocean (audio)

Baby oysters could be the “canaries in the mine shaft” for another dimension of global warming. That from Northwest scientists who are studying how the oceans suck in excess carbon dioxide from the atmosphere. The process changes seawater chemistry — locally and globally. Correspondent Tom Banse reports on an experiment now underway in Seattle to find out which sea critters can or can’t cope.


You can think of Paul McElhany’s lab as an ocean time machine.

Paul McElhany: “In one of the tanks we’re simulating pre–industrial conditions, before people started burning fossil fuels.”

McElhany is a federal biologist working at the Northwest Fisheries Science Center in Seattle.

Paul McElhany: “This tank here is the current, where we are now.”

Multicolored tubes and pipes lead every which way in the cramped aquatic lab. The researcher controls his time machine by bubbling carbon dioxide into seawater at different concentrations.

Sound: (Burbling.)

Paul McElhany: “The next tank over we’re setting conditions of a doubling of the current CO2 levels, which the models that have been done project we’ll reach by 2100, by the end of the century or before.”

There’s one additional setup with an even worse scenario. McElhany explains the oceans absorb a big chunk of the CO2 we pump into the atmosphere. This is the lesser known twin of atmospheric warming. Scientists call it “ocean acidification.”

Paul McElhany: “As the CO2 that’s put out by burning fossil fuels goes into the ocean, it changes the chemistry of the ocean itself and makes it more acidic. It’s sort of the same way as when you have carbon dioxide in a soda pop, that makes the soda pop more acidic.”

Tom Banse: “Are there likely be winners and losers in the ocean?”

Paul McElhany: “Yeah, ocean acidification is not going to affect all species equally.”

McElhany’s team is out to find out just who wins and who loses. He says on the one hand, algae and seaweed could prosper under elevated carbon dioxide. On the other hand, shellfish in the larval stage seem quite vulnerable.

Paul McElhany: “If the acidity gets low enough, they can actually start to dissolve.”

First into the bath, baby oysters. The little specks are taking an extended dip now with the ghosts of oceans past, present and future. Next up, geoducks, clams, mussels, abalone and krill. Grad students check the tanks and jars every day to monitor how many larvae survive and in what condition.

Sound: (In lab.) “The larvae are now swimming. They’ve hatched.”

At Oregon State University, researchers are waiting to hear if the National Science Foundation will provide money for a similar experiment. Newport, Oregon based fisheries professor Chris Langdon agrees oysters are likely to show the effects of a more acidic ocean first.

Chris Langdon: “From what we can tell, the larvae of the Pacific oyster seem to be much more sensitive to what’s going on than larvae of mussels or clams. So they are kind of the canary in the mine shaft.”

Northwest oyster growers already report having serious problems with oyster seed survival. They blame it on acidified water. Chris Langdon says a frustrating discovery is that it’s hard to get high levels of dissolved carbon dioxide out of seawater once it’s in there. So where does that leave people like north Puget Sound oysterman and clam grower Bill Dewey?

Bill Dewey: “The likelihood of turning it around anytime soon is not good. So we’re definitely, in our industry, we’re in the adaption mode, trying to find things we can do to the seawater chemistry in our hatcheries to allow us to produce the seed.”

Possible water treatments for aquaculture farms would be part of the planned Oregon State experiment. Dewey says he’s heartened by the scientific attention directed at his industry’s problem. The stakes are high. Oyster growers alone generated more than $70 million in sales from the West Coast last year.

I’m Tom Banse in Seattle.

Tom Banse & Chris Langdon, KUOW.ORG, 15 September 2010. Article and audio.

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