Sea change

An acid peril is rising from the depths and falling from the air. It kills local oysters and threatens everything that lives in the sea.

Around 10 years ago, Jeremy Brown noticed something strange hanging from his hooks. Brown is a troller, sailing solo out of Bellingham in a 42-foot boat he named the Barcarole, after a genre of Italian boatmen’s tunes. He deploys as few as a dozen or as many as 70 hooks at a time, depending on whether he’s after halibut, black cod, or albacore, or king, pink, or coho salmon. Trolling is about as clean as commercial fishing gets; it pulls up very little untargeted bycatch or sea-bottom debris. But now and then Brown’s hooks snag a branch of coral from the little—studied deepwater reefs that, unbeknownst to many locals, lie off the Northwest coast.

For two decades the coral samples Brown pulled up looked radiantly healthy, “nice, crisp, brightly colored.” Now, he says, “the coral tends to look dull and lifeless. And it’s covered with slime.” Brown puzzled over the change.

The ability of marine creatures to lay up calcium carbonate—to build shells and coral reefs—depends on the chemical balance of the water in which they live. One thing that affects this balance is carbon dioxide, which gets released when humans burn oil, coal, and forests and when, say, a dead whale decomposes on the sea floor. Seawater absorbs carbon dioxide and converts it to carbonic acid. As acids go, carbonic is mild stuff; it gives carbonated beverages their tang. But it has dire effects on calcifying critters, reducing the carbonate concentration in water and hindering them from developing shells and skeletons. If it gets strong enough, it dissolves those shells.

In life, these calcifying organisms are key parts of the marine food chain, starting with phytoplankton. Several that swim in vast clouds around the world—crustacean krill and copepods and tiny snail-like mollusks called pteropods—are essential food for young salmon and for the little fish that adult salmon and other big fish eat. Others—oysters, clams, and mussels—are prized food for humans.

Down the coast, Sue Cudd and Mark Wiegardt, wife and husband, have been growing oysters for decades. Cudd, a biologist, operated the Whiskey Creek Shellfish Hatchery on Netarts Bay, near Tillamook, Oregon. Wiegardt managed oyster farms on Willapa Bay, where his family had been in the oyster business since the 1880s. Four years ago Wiegardt moved to Tillamook and joined his wife in running Whiskey Creek—just in time to see its business crater.

Whiskey Creek produces oyster larvae, aka seed, for growers from Mexico to British Columbia. In 2007 those larvae started dying en masse; midway in their cycle their shells mysteriously stopped growing. The next year Wiegardt and Cudd lost 80 percent of their larvae. At first they thought they had a culprit: a bacterium called Vibrio tubiashii that perennially threatens oysters. But cleaning out the bacteria didn’t stop the carnage. They came to suspect that V. tubiashii was “more a symptom of the problem” than a cause. “It’s opportunistic,” says Wiegardt. “It eats dead and dying material.” Like many bacteria, it thrives in acidic conditions.

Eric Scigliano, Seattle Metropolitan, March 2010. Full article.

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