Bay Area Oysters Show Symptoms of Climate Change, Researchers Claim

Posted on NBC Bay Area: 10 Sep 2014 — By Joe Rosario — Featuring Hog Island’s Terry Sawyer and BOAR’s Dr. Tessa Hill

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On a clear, crisp day in the tiny West Marin town of Marshall, clusters of visitors to the Hog Island Oyster Company feasted on raw oysters with an elaborate array of fixings. Barbecues were lined with shellfish as picnicking diners dripped exotic vinegars and other sauces onto the shells.

Not far away, in a rustic wooden shed tucked among the bubbling oyster tanks, scientist Tessa Hill stared into a computer screen – the technological implement standing in contrast to the quiet bay surroundings.

“We’re helping the oyster company monitor the water that’s flowing over these oysters,” Hill said, gesturing to a set of plastic pipes carrying water from the nearby Tomales Bay into the company’s gurgling tanks.

A staff researcher at the nearby Bodega Bay Marine Laboratory, Hill has been studying the effects of a marine condition known as “ocean acidification” and its impact on shellfish such as oysters. The phenomenon is the result of carbon dioxide pollution accumulating in the ocean, reducing the PH balance, and causing a rise in acid.

“When we generate carbon dioxide that’s been put in the atmosphere,” Hill said, “the ocean sucks it up like a sponge.”

For the last two years, the Bodega Bay laboratory has teamed up with Hog Island to monitor the company’s water. The system of computers and sensors provides the oyster operation’s managers with real-time information about the condition of the water’s chemistry.

“We hand all that information to them,” said Hill, “so they can actually make changes to the water supply that goes to these oysters that they’re raising.”

In recent years, ocean acidification has been considered the prime suspect in large-scale collapses at West Coast oyster breeding operations, which supply the larvae, or “seed” to companies like Hog Island.

“We’ve been having issues with sourcing what we call seed, or baby oysters from hatcheries up and down the West Coast,” said Hog Island co-founder Terry Sawyer. “We’ve been having crashes or die-offs of their entire inventories.”

Hill said studies at her laboratory have shown higher than normal levels of acid can cause oysters to grow smaller, thinner shells – making them more susceptible to predators. Sawyer said difficulty finding seed for his oyster beds can have a devastating impact on his business.

“When you have a product where you go to plant that seed and it takes, two to three to five years to grow out,” Sawyer said. “You’re affected for five years.”

While Sawyer hasn’t experienced a collapse like the hatcheries, he has recorded water levels low in oxygen and high in acid. Scientists have called ocean acidification a symptom of the larger issue of climate change.

“We can talk all day long about whether climate change is happening,” said Sawyer, gazing out toward the bay. “But this is a component of climate change we know is happening, we can see it happening.”

Hill said the addition of naturally occurring chemicals can help counteract the high acid levels in the oyster tanks. But the big picture is far more complicated.

“There’s really only one big thing we can do as the whole world,” said Hill, “which is to decrease our use of fossil fuels so that we emit less carbon dioxide to the atmosphere.”

The Bay Area’s oyster industry is already struggling to keep up with demand. Shellfish industry suppliers said the pending government shutdown of the nearby Drake’s Bay Oyster Company will pose a huge hit to the commercial oyster supply. Sawyer said more complications, such as pollution and nature, could only exacerbate the problems.

“At the same time we’ve got to be planning for the future,” Sawyer said.