JUDY WOODRUFF: An increase in carbon emissions are showing up not only in the air, but also
in water.
As Oregon Public Broadcasting's Jes Burns reports, researchers and shellfish farmers
are teaming up to see how marine plants can help stave off the effects of ocean acidification.
This report was produced in collaboration with the public media partnership EarthFix
and is part of this week's Leading Edge series, which focuses on science, tech and medicine.
JES BURNS: Tide is money at Baywater Shellfish farm West of Seattle.
WOMAN: These geoduck are so big.
JES BURNS: The tide flat is exposed for only a few hours a day, and there's work to be
done in the geoduck clam patch, pulling tube.
MAN: These guys are really hard to pull out.
JES BURNS: The tubes kept the clams safe the first two years of their lives.
Joth Davis owns Baywater, part of the Pacific Northwest's $200 million shellfish industry.
He grows geoduck for export and other clams and oysters for local markets on the West
Coast.
But both his business and the industry are in trouble.
JOTH DAVIS, Owner, Baywater Shellfish Company: It's just more difficult to raise oyster larvae
these days than it used to be.
They used to be kind of weedy, and you could grow oyster larvae easily.
Now it's not the case.
JES BURNS: That's because the ocean's chemistry is changing.
It's called ocean acidification.
And it's in part caused by people pumping carbon dioxide into the atmosphere at unprecedented
rates.
The ocean acts like a giant carbon sponge.
And all that extra CO2 causes the pH of the seawater to decrease.
But it's not really the acid that's hurting shellfish.
Baby oysters use certain compounds to build their shells.
The same chemical reaction that lowers the pH of the water transforms those building
blocks into something the oysters can't use.
And the more carbon there is, the more difficult it could become for any sea creature with
a shell to survive; 250 miles south, along Oregon's coast, scientists like George Waldbusser
are discovering a common aquatic plant called eelgrass could make a big difference.
Eelgrass is like other plants that use photosynthesis.
It gets energy by absorbing sunlight and carbon dioxide.
And that could lessen the effects of ocean acidification.
GEORGE WALDBUSSER, Oregon State University: They're the same species of oysters.
On this shell, what we have are Pacific oyster larvae or juveniles.
All these dark areas are individual oysters.
And these have been grown in the eelgrass bed.
And then, on this shell, we have again small oysters, fewer of them, and much smaller that
have been grown not in the eelgrass bed.
JES BURNS: Fellow Oregon State University researcher Caitlin Magel has been stopping
at estuaries in Oregon and Washington, taking random samples from the flats.
She's trying to get a handle on just how much carbon these shallow eelgrass beds are pulling
out of the water by sampling the plants' shoots and roots.
CAITLIN MAGEL, Oregon State University: They have this below-ground carbon storage that
can lead to long-term sequestration of carbon.
JES BURNS: Eelgrass could benefit shellfish growers in different ways.
CAITLIN MAGEL: It could be grown in and amongst, for instance, an oyster aquaculture bed.
Or, in the case of a shellfish hatchery, they could pinpoint where they're drawing their
water in from, so that they are drawing from within an eelgrass bed.
JES BURNS: And that water would have more of those shell-building compounds needed by
the oysters to grow.
Back at Baywater, Joth Davis wants to take the idea of using ocean plants to sequester
carbon to a new, deeper and tastier level.
JOTH DAVIS: We got some fresh sugar kelp.
It's a little tough, but it's definitely edible and yummy.
JES BURNS: A team organized by Davis and Puget Sound Restoration Fund director Betsy Peabody
has been tracking kelp growth at a nearby test plot.
BETSY PEABODY, Director, Puget Sound Restoration Fund: What we're trying to do is deliberately
grow kelp within a specific area, and thereby remove CO2, and measure whether or not that
improves conditions locally.
You could create, in theory, a kind of seaweed filter, you know, a curtain around where you're
growing shellfish.
JES BURNS: Much of the kelp is more than six feet long, and that mass of algae is evidence
of carbon pulled from the water.
JOTH DAVIS: I'm looking at interspersing shellfish in baskets, hanging below buoys, and then
every other line would be kelp.
Between the two of them, we will be able to harvest kelp and shellfish.
JES BURNS: Marine plants aren't likely to provide relief from carbon emissions on a
broad scale.
But for shellfish growers and researchers in the Pacific Northwest, the greener grass
on the other side of ocean acidification is beginning to look more like tide-swept eelgrass
and towering forests of kelp.
For "PBS NewsHour," I'm Jes Burns on Washington's Hood Canal.