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The Great Oyster Crash

image of Eric Scigliano
Oysters threatened by ocean acidification
Americans eat 700 million oysters every year, but ocean acidification could make them harder to raise, driving up prices for shellfish lovers.
Ocean acidification hits the Pacific shellfish industry

In the summer of 2007, something strange and troubling happened at the Whiskey Creek Shellfish Hatchery on Netarts Bay in Oregon, which raises oyster larvae for shellfish growers from Mexico to Canada. The hatchery’s "seed," as the oyster larvae are called, began dying by the millions, for no apparent reason.

Disease isn’t uncommon in a hatchery’s tanks, but that same year, up the coast in Washington, wild oyster larvae also failed in Willapa Bay, which has been the heart of the Pacific Northwest’s oyster industry since the 1850s.

The Willapa Bay growers scrambled to replace their natural beds with farm-raised seed from Whiskey Creek and other hatcheries. But there was very little of it to buy. Washington state’s Taylor Shellfish Farms, the Pacific Coast’s largest grower, also lost most of its larvae that year.

The situation was dire. Whiskey Creek and Taylor are key links in the nation’s seafood supply chain. They and another Washington hatchery provide nearly all the seed for the West Coast’s growers, who in turn produce more than a quarter of the 700 million or so farmed oysters that Americans slurp down every year.

Suddenly, it seemed, seafood lovers might have to do without their slippery delicacies, or at least pay a lot more for them. Growers on the Gulf and Atlantic coasts wondered if whatever was striking the Pacific hatcheries might soon hit them. And when the culprit was finally revealed, it provided the first example of how a worldwide crisis in ocean chemistry could devastate coastal economies and change restaurant menus across the country.

Whiskey Creek is owned by the husband-and-wife team of Sue Cudd and Mark Wiegardt. Wiegardt grew up tending oysters on Willapa Bay, where his family has been farming them since the late 1800s. Cudd, a fisheries biologist, got a job at the Wiegardt operation in 1984 and married Mark in 1989. She began managing the 33-year-old Whiskey Creek Hatchery in the mid-90s, and the couple took over the business together in 2002.

At the sprawling, barn-like warren about two hours west of Portland, where cylindrical plastic tanks serve as incubators for shellfish larvae and algae, a big part of their job is to keep vigilant watch for infections. When the 2007 crisis hit, Cudd and Wiegardt set about solving it according to standard industry practice: by looking for whatever pathogen might be making their "babies" sick.

NRDC: Acidic Oceans

Lisa Suatoni

Q&A with NRDC senior scientist Lisa Suatoni

How closely is ocean acidification related to global climate change?

Ocean acidification and global climate change are two -- independent -- impacts of rising atmospheric CO2 concentrations.  When fossil fuels are burned, carbon dioxide is produced. Approximately two thirds of that CO2 goes into the atmosphere, where it causes global warming; the remaining third is absorbed by the world’s oceans, where it causes ocean acidification. Two problems, one culprit.

Read the rest here.

They eventually found a larvae-eating bacterium called Vibrio tubiashii raging through their tanks. Attacking it with maximum force, they hired an engineer-turned-hatchery manager from Oregon State named Alan Barton to build a $200,000, state-of-the-art system to filter and sterilize the water they drew from the bay. It squelched the vibrio but failed to stop the carnage; the infestation, it seemed, was a symptom of some underlying problem, rather than the cause. The larvae were still dying, and Cudd and Wiegardt were facing ruin. So were many of the Pacific oyster farmers who relied on them.

Wiegardt has a farmer’s weatherbeaten face and stoic manner. Like all farmers, he’s used to boom and bust cycles. But even he started to despair. "The frustrating thing is people in the industry saying, 'It’s got to be something you’re doing wrong.'" His colleagues and competitors stopped their scoffing as news of other die-offs began to trickle in. In 2008, in an unprecedented cooperative effort for the industry, the Pacific Coast Shellfish Growers Association declared a "seed supply crisis." It persuaded its members to donate $40,000 so that Wiegardt and Cudd could keep Barton on the payroll and on the hunt for the culprit, in hopes of helping eradicate it elsewhere.

"We’d done everything we could to eliminate bacteria," Barton says in his native Georgia drawl. He began to wonder if something more fundamental might be amiss -- something in the makeup of the sea itself. "Shellfish hatcheries never worried about chemistry, just infections. I was back to being a 14-year-old kid with an aquarium, worrying about water chemistry."

Uncovering a Killer

In July 2008, all of the remaining larvae at Whiskey Creek died suddenly. At the same time, the water in Netarts Bay (and hence in the hatchery’s tanks) became noticeably more acidic -- an indication that it had welled up from lower depths offshore.

This wasn’t entirely unexpected: Each summer, the north wind periodically pushes back the water along the Oregon coast, allowing deep, cold offshore water to surge in toward land. Barton checked federal CoastWatch reports and confirmed that a strong upwelling had been underway at the time the larvae died.

It was the breakthrough Whiskey Creek’s operators had been waiting for. The culprit behind their die-offs, it turned out, was part of a much bigger change in oceans around the world. Called "ocean acidification," it results from too much carbon dioxide in the atmosphere. The sea is the world’s great carbon sink, holding about 50 times as much of the element as the air. Phytoplankton at the ocean’s surface absorb carbon dioxide for photosynthesis, and when the tiny plants die, they sink and decompose, releasing CO2 into the water column. Dissolved CO2 forms carbonic acid, the same weak acid that gives soda water its tang. Cold water can hold more CO2, so the frigid waters at the ocean bottom are more carbon-saturated, and more acidic, than the warmer surface water above.

Some people think that’s a good thing; scientists and engineers have even proposed pumping CO2 into the deep ocean for storage, as a possible strategy to slow global warming. Trouble is, that acidified water doesn’t stay down in the deep: it rolls back to the surface along the West Coast and other upwelling zones.

These nutrient-rich upwellings, full of sunken organic matter and minerals, support a famously rich marine food chain, from microscopic plankton to eight-ton killer whales. But if the waters become too acidic, they’re lethal to many shell-building creatures -- including young clams and oysters, whose formative coverings are uniquely vulnerable in their first week or two of life.

Even as the hatchery folks were struggling with acidifying water inshore, scientists from Mexico, Canada, and the United States were documenting similar changes in the waters further out. They found that the upwellings operated on a time lag: The water rising from the depths today holds CO2 absorbed about 30 to 50 years ago, when expansions in transportation, industry, and other 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, one of the scientists who conducted the offshore research, "and it’s hard to call off delivery."

Adaptation in Action

Sue Cudd and Mark Wiegardt didn’t have time to worry about future deliveries; they had to protect their oysters now. That meant rethinking their operation from the sea bottom up.

"We used to think cleaner water was better," Cudd says, and so they purified and filtered relentlessly. But seawater chemistry is devilishly complex and hard to manipulate. Cudd and Wiegardt decided they had to learn to make better use of the water the ocean was giving them, but to do that they needed to know precisely what was in it. Unfortunately, their monitoring gear, like that of most in the industry, was minimal and crude. "We were driving down the road blind," sighs Wiegardt.

image of Eric Scigliano
Seattle-based Eric Scigliano has written about Northwest marine and environmental issues for more than 20 years. His books include Puget Sound, Love War and Circuses, Michelangelo’s Mountain, and Flotsametrics: How One Man’s Obsession with Floati... READ MORE >
What is so sad about this is the contribution to vibrio's potency by the massive spraying of herbicides, with surfactants, at taxpayer expense, which has gone on in places like Willapa Bay. The excuse for doing this is the trusty concept of invasive species. There is one planet. Life forms carry other life forms around. Add in climate manipulation, when the earth is scraped of forests and when its soil is killed, and it is a prescription for major harm to life and diversity of life. The scraping of forests and the killing of soil contribute to acidification of the oceans. The use of the word invasive is a marketing and subsidy-seeking ploy. I believe there will be increasing consciousness of this as the damage from killing soil and sea becomes more evident.