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.
In 1999, Brown read in the journal Nature about a company named Planktos, which proposed to stop global warming with a painless geoengineering scheme: seeding the sea surface with powdered iron, a key nutrient for phytoplankton. This, Planktos argued, would grow bumper plankton crops, which would take up carbon dioxide via photosynthesis. Then the plankton would die and sink to the bottom, locking up all that carbon. At the same time, other geoengineering advocates proposed capturing CO2 from power plants and burying it deep underwater. To Brown, these schemes sounded “crazy—just another way of dumping pollutants into the ocean. You’re essentially just pushing crap back up the pipes.”
Brown wondered just what that crap did in the sea. He read more about the role of carbon in the ocean’s chemistry. And he remembered the deathly coral stubs his hooks had snagged.
Coral polyps are little animals that look like miniature sea anemones. They build collective skeletons, which can form fantastic shapes and sprawling reefs, by extracting a mineral called calcium carbonate from seawater. They share this trick, called calcification, with a vast array of shelled and plated organisms: single-celled algae and other phytoplankton, barnacles and snails, starfish and sea urchins, shrimp and crabs. When they die, their shells and skeletons accumulate and, squeezed and heaved by geologic forces, become rocks and mountains: limestone and marble, the chalky white cliffs of Dover.
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.
Published: March 2010
Thanks for an excellent article.
We know what the cause is… and we know what to do about it.
The obstructions now are political