Oysters Killed by Climate Change’s Evil Twin
The oyster industry is in trouble. A few years ago, oyster hatcheries in the Pacific Northwest began losing their “seed,” as oyster larvae are known, by the millions. They scrambled to figure out what was behind the massive die-off and discovered that it had to do with “ocean acidification,” also known as climate change’s evil twin.
As with climate change, ocean acidification happens when there’s too much carbon dioxide in the atmosphere. The earth’s waters absorb some of that CO2 — more than a quarter of the amount that we produce — as a way of achieving chemical equilibrium between water and air. “When CO2 mixes with seawater,” Jim Meyer explains, “it creates carbonic acid, and, spoiler alert, increasing acid in the oceans makes the oceans more acidic.”
Acidified waters are deadly for sea creatures like oysters which have a hard time forming shells in that environment. The CO2 buildup can also cause “stunted growth, reproductive failure, respiratory problems, and even death,” writes Meyer. In past years, as Sarah Henry reported for Grist, Terry Sawyer of Hog Island Oyster Company would buy 7 million oyster seeds from hatcheries, but this year he was only able to buy 2.5 million, and they were significantly smaller, which reduces their chances of survival.
Some hatchery owners and oyster growers like Sawyer are collaborating with scientists to save the bivalves, and they are already making some progress. Scientists from UC Davis’s Bodega Marine Laboratory are monitoring the waters in Tomales Bay and, using that data, are advising the folks at Hog Island who now know, for example, how and when to change the water flow in their tanks to avoid low pH levels. “The only reason we still have oyster farmers on the West Coast,” said Brad Warren, a member of Washington’s Blue Ribbon Panel on Ocean Acidification, “is because they were extraordinarily lucky, smart, and resourceful.”
The problem of ocean acidification is only going to get worse. As Eric Scigliano explains, the frigid waters at the bottom of the ocean can hold more carbon and is therefore more acidic than warmer waters above. In time, those acidified waters make their way to the surface along the West Coast and other upwelling zones. Scientists have found that the cycle operates on a time lag:
The water rising from the depths today holds CO2 absorbed about 30 to 50 years ago, when… human activities began pushing increased amounts of carbon into the atmosphere.
Because carbon emissions have continued rising since, future upwellings are sure to be even more acidic. “We’ve mailed a package to ourselves,” says Oregon State oceanographer Burke Hales,… “and it’s hard to call off delivery.”
By working with scientists to restore oysters to a more hospitable environment, oyster growers and hatcheries on the West Coast are trying to save their own livelihoods. But oysters are also vital to the ecosystems in which they are found. As a keystone species, they provide habitat for other marine life in addition to filtering and cleaning the water for the organisms around them — up to 50 gallons per day by an individual oyster.
It’s in large part because the oyster industry has taken initiative by reaching out to scientists that there is hope yet for saving these creatures, not to mention the ecosystems they help to support. But the work has only just begun.
Photo from Thinkstock