Oyster Enemy Number One: Ocean Acidification

Corrosive ocean water is preventing baby bivalves from thriving.

oyster beds in the ocean
Add acidification to the growing number of threats to aquaculture operations. (Photo: Raymond Roig/Getty Images)
Clare Leschin-Hoar's stories on seafood and food politics have appeared in Scientific American, Eating Well and elsewhere.

When experts talk about feeding a burgeoning world, they’re often referring to land-based crops, and frequently butt heads over whether it can be done by planting organic versus genetically modified crops. But farmers aren’t the only food producers thinking about how to feed 9.1 billion hungry mouths by 2050. The worldwide aquaculture industry is on pace to grow from 65.8 million tons in 2008 to a hefty 100 million tons by 2030, much of that by growing bivalves such as clams, mussels and oysters.

Unlike raising carnivorous fish like salmon or bluefin tuna, which devour precious forage fish, often in the form of fishmeal; shellfish leave little in the way of an environmental footprint. They don’t need supplemental feed, antibiotics or pesticides. They have the added benefit of cleaning the water in our bays and estuaries. Plus, they’re tasty. It’s a win-win, and many in the industry hope aquaculture—particularly bivalves—will be a real solution to providing the world with a sustainable source of healthy protein, without us resorting to snacking on crispy insects.

There’s just one big problem with this picture. The oceans are changing. Sea levels are rising, the water is getting warmer, and carbon dioxide in the air—which just reached a startling 400 parts per million in the Arctic—is being dissolved in the ocean. It’s known as ocean acidification, and it has very troubling ramifications for those betting on shellfish.

More sobering? It’s already here.

In 2008 and 2009, Taylor Shellfish Farms and Whiskey Creek Shellfish Hatchery were witnessing massive losses of oyster larvae. Corrosive ocean water prevented baby oysters from thriving and growing shells.

According to Bill Dewey of Taylor Shellfish Farm, Senator Maria Cantwell (D-WA) secured funds to supply the industry with sophisticated monitoring equipment to measure the changes in the water’s chemistry—particularly deeper water brought to the surface by upwelling conditions or rough weather.

“It was like putting headlights on the car,” Dewey tells TakePart. “We could now monitor [PH and CO2] levels in real time. We learn every year how to adapt [by using surface water], and have learned how to manage around the corrosive water by dodging it.”

But dodging a problem only gets you so far. A report released by the National Science Foundation in April, definitively linked the collapse at the hatcheries to an increase in ocean acidification. The dots were now connected.

In the meantime, many producers, scientists and government officials have been working furiously on the issue. Washington Gov. Christine Gregoire established a blue ribbon panel to address the issue and to look for solutions. At a meeting June 20, members of that panel will be getting ready to present their recommendations.

“We are on the front line,” says Betsy Peabody, executive director of Puget Sound Restoration Fund and member of the Blue Ribbon Panel. “Water that’s been traveling around the globe collecting CO2 is being delivered to our shores. We hope the actions we develop will be useful in other parts of the country.”

We hope so too, and will be eagerly watching this month’s meeting. And not to hammer home the point too fiercely, but the looming problem of ocean acidification? It isn’t limited to oysters.

“What’s happening here is a warning to the rest of the seafood industry,” says Dewey. “This is a real phenomenon. It impacts any creatures that rely on calcium to form shells or skeletons. Even something like a terrapod—a swimming marine snail that’s the primary food for salmon is affected. Take the base of the salmon prey out, and it could very well impact salmon populations.”

Are you worried about the state of our oceans?

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