Can Seagrass Save Shellfish From Climate Change?

Jan 30, 2018
Originally published on February 1, 2018 5:55 pm

The impacts of climate change aren't a far-off possibility for the Pacific shellfish industry. Acidifying seawater is already causing problems for oyster farms along the West Coast and it's only expected to get worse.

That has one Bay Area oyster farm looking for ways to adapt. It's teaming up scientists who are studying how the local ecosystem could lend a helping hand.

"We need help," says Terry Sawyer of Hog Island Oyster Company. "That 'canary in a coalmine' analogy drives me crazy, but that's what we are."

Sawyer's natural habitat is on the mudflats of Tomales Bay, about 50 miles north of San Francisco, where his oyster operation is located. But a few years ago, he started going to climate change conferences, sitting next to scientists and policymakers.

"Carbon chemistry is incredibly sophisticated, complicated science," he says. "I am definitely out of my element. Out of my comfort zone. I'd rather be in shorts and no shoes."

To him, it was a necessity. Like a lot of oyster farmers, he buys baby oysters from hatcheries in Oregon and Washington. But starting a decade ago, the hatcheries began having mysterious die-offs.

"The orders that we were getting – if we were getting them at all, they wouldn't necessarily happen at the time or the size that we could take them," he says.

Scientists eventually identified the main culprit: acidifying seawater.

At least a quarter of the carbon humans put into the atmosphere from burning fossil fuels is soaked up by the ocean. It acts like a carbon sponge, but adding carbon to seawater makes it more acidic. Since the start of the Industrial Revolution, the oceans have become about 30 percent more acidic.

It's harmful for animals that build shells, like oysters, and spells big trouble for the Pacific shellfish industry, worth more than $100 million.

"You don't want to curl up in a fetal position," says Sawyer. "You do want to say we've got to move on this and we need help."

Sawyer found some help by opening up his oyster farm to a team of scientists.

The water's acidity is monitored with real-time equipment, part of a network run by UC Davis's Bodega Marine Lab.

"That was a significant move: knowing what's going to day-to-day, minute-by-minute," he says. "And it's also been proving the point. We have numbers you can't argue with."

Hog Island is also opening its own oyster hatchery in Humboldt Bay to improve the reliability of the supply chain.

The oyster farm is also assisting with cutting-edge scientific research, focused on how oysters could get a boost from native plants in Tomales Bay.

On a sunny morning, a team of scientists is scuba-diving in a shallow part of the bay, surrounded by thick, green seagrass, waving in the current.

"When you're down in it, it really feels like you're in a forest of seagrass," says Kristy Kroeker, professor of marine biology at UC Santa Cruz. "It's quite long."

This seagrass is a glimmer of hope for oyster farmers. Plants, whether it's a forest or lawn, take up carbon dioxide and use it for photosynthesis.

"The plants under the water are doing the exact same thing," Kroeker says.

The seagrass pulls the carbon out of the water, which makes it slightly less acidic.

"Essentially, they're creating this little bubble of seawater around them that's more friendly for animals that might be threatened by ocean acidification," she says.

Kroeker is trying to find out if the seagrasses could act as a buffer, protecting the oysters nearby.

She plants mesh bags of baby oysters in the seagrass bed, which she'll be watching in the months to come. So far, the results look promising, but not necessarily the whole answer.

Seagrass can reduce acidification around it, but potentially only in certain locations or at certain times of year. More research will be needed, Kroeker says, but against a global problem, local approaches have a lot of potential.

"Can we use parts of nature that we already know are important – seagrasses – to actually benefit people and protect them from some of these impacts?" she says.

The approach is being studied around the world in different ecosystems, including near coral reefs, and using bigger marine plants, like kelp.

Eventually, it'll be up to oyster farmers like Terry Sawyer to make the research work on the ground – or, in the water.

"From an aquaculture point of view, you bet I'm hopeful," Sawyer says. "Maybe I'm being idealistic here. But we're learning so much. We're just at the tip of the iceberg on that."

Copyright 2018 KQED. To see more, visit KQED.

ARI SHAPIRO, HOST:

If you're one to enjoy a big plate of briny oysters, here's some not-so-good news. Climate change is already causing problems for the oyster industry up and down the West Coast, and it's only expected to get worse. As Lauren Sommer reports from member station KQED, one oyster farm is teaming up with scientists to find a way to adapt to it.

LAUREN SOMMER, BYLINE: The hotel conference room is jam-packed with political types - lobbyists, policymakers, experts and Terry Sawyer, wearing a blue blazer, trying hard to fit in.

TERRY SAWYER: I am definitely out of my element, out of my comfort zone. I would rather be in shorts and no shoes.

SOMMER: Sawyer is an oyster farmer. He runs Hog Island Oyster Company north of San Francisco. And normally he's knee-deep in mud. But a few years ago, he started going to climate change conferences like this one, trying to understand it. Today he's going on stage as a speaker with a message.

SAWYER: We need help. We're - that canary in a coal mine analogy drives me crazy, but that's we're we are.

SOMMER: To see why, I meet Sawyer on more familiar turf.

What kind are these?

SAWYER: These are sweetwaters. It's a Pacific oyster.

SOMMER: Workers are sorting a huge pile of fresh oysters which have just come out of Tomales Bay right behind us. Sawyer first started hearing about climate change a decade ago. Like a lot of oyster farmers, he buys baby oysters from hatcheries in Oregon and Washington. But the hatcheries were having mysterious die-offs.

SAWYER: The orders that we were getting - if we were getting them at all - they wouldn't necessarily happen at the time or the size that we could take them.

SOMMER: And the main cause - acidic seawater. A lot of the carbon we humans put into the atmosphere is soaked up by the ocean. It's like a carbon sponge. But that's made the water more acidic - about 30 percent more. It's tough on animals that build shells - in other words, bad news for the Pacific shellfish industry, which is worth more than a hundred million dollars.

SAWYER: You don't want to curl up in a fetal position, but you do want to say, we've got to move on this, and we need help.

SOMMER: So Sawyer found help by teaming up with scientists.

KRISTY KROEKER: And we're off.

SAWYER: Good luck.

(SOUNDBITE OF WATER SPLASHING)

SOMMER: Kristy Kroeker is a professor at UC Santa Cruz. She's scuba diving in a shallow part of Tamales Bay surrounded by thick, green seagrass waving in the current. This grass is a glimmer of hope for oyster farmers. Plants, whether it's a forest or your lawn, take up carbon dioxide and use it for photosynthesis.

KROEKER: The plants under the water are doing the exact same thing.

SOMMER: By using the carbon, the seagrass makes the water slightly less acidic.

KROEKER: So essentially they're creating this little bubble of seawater around them that's more friendly for animals that might be threatened by ocean acidification.

SOMMER: It's a buffer. So Kroeker is putting baby oysters into the seagrass beds to figure out if that could protect them.

(SOUNDBITE OF WATER SLOSHING)

SOMMER: So far the results look promising but not necessarily a silver bullet. Seagrass can reduce acidification around it but maybe only in certain locations or certain times of year. But against a global climate problem, these local approaches have a lot of potential, Kroeker says.

KROEKER: Can we use parts of nature that we already know are important - seagrasses - to actually benefit people and protect them from some of these impacts?

SOMMER: The approach is being studied around the world in different ecosystems or using bigger marine plants like kelp. But eventually it'll be up to oyster farmers like Terry Sawyer to figure out how it can make a difference on the ground. For NPR News, I'm Lauren Sommer. Transcript provided by NPR, Copyright NPR.

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