Young oysters, a.k.a. "oyster seeds," are increasingly vulnerable as the ocean absorbs carbon and becomes more acidic.
Young oysters are increasingly vulnerable as the ocean absorbs carbon and becomes more acidic.

Behind the counter at Seattle’s Taylor Shellfish Market, a brawny guy with a goatee pries open kumamoto, virginica, and shigoku oysters as easily as other men pop beer cans. David Leck is a national oyster shucking champion who opened and plated a dozen of them in just over a minute (time is added for broken shells or mangled meat) at the 2012 Boston International Oyster Shucking Competition. You have to be quick, these days, to keep up with demand. The oysters here were grown nearby in Taylor’s century-old beds, but the current hunger for pedigreed mollusks on the half shell stretches to raw bars and markets across the country.

A similar oyster craze swept the United States in the 1800s, when the bivalves were eaten with alacrity in New York, San Francisco, and anywhere else that could get them fresh. Development of a fancy new technology, canning, meant there was money in preserved oysters, too. Gold miners in Northern California celebrated their riches with an oyster omelet called hangtown fry. New Yorkers ate them on the street; late at night they ate them in “oyster cellars.” Walt Whitman had them for breakfast.

That wave crashed. By the early 1900s, oysters were disappearing because of overharvesting and water pollution. Today’s revival is possible because oyster farms are better managed, and regulations have improved water quality. But a modern threat looms for ice-chilled fruits de mer platters, although it’s hard to tell with oyster juice on your chin. This time it’s a worldwide problem, affecting marine ecosystems everywhere. Ocean waters are turning corrosive, and it’s happening so quickly scientists say there may not be any oysters left to eat in coming decades.

Ocean acidification, as scientists call this pickling of the seas, is, like climate change, a result of the enormous amount of carbon dioxide humans have pumped into the atmosphere. Oceans have absorbed about a quarter of that output, and ocean chemistry has changed as a result. Surface water pH has long been an alkaline 8.2, not far from the pH of baking soda, but it now averages about 8.1. That doesn’t look like much, but since pH is a logarithmic scale, that means a 30 percent increase in the acidity. By the end of this century, surface water pH could further lower to 7.8 or below.

We don’t yet know who the ocean’s winners and losers will be in the more corrosive world.