Oysters May Offer Insight Into Our Changing Oceans

The California seafood industry supports thousands of jobs. It pours as much as $100 million into the economy and it brings us delicacies, like Pacific oysters. But all of this is at risk, because of more carbon dioxide in the ocean now. And scientists say that the window of opportunity to make a difference is closing.

TRANSCRIPT:

Madeleine Brand: Oysters. Few people are ambivalent about them. They're either slimy or sublime.

For thousands of years oysters have inspired artists and writers. Shakespeare coined the phrase "the world is my oyster." These creatures with their gnarled shells symbolize the riches the world has to offer -- if you have the cunning to crack them open.

Now though, oysters represent something ominous: vanishing riches and the threat of climate change.

Growing carbon dioxide levels are leading to warmer atmospheric conditions. And that's what's brought us a couple of dramatic "100-year storms" like Sandy, which devastated parts of New York and New Jersey.

Those same rising CO₂ levels are also to blame for invisible changes below the ocean surface -- a rise in acid levels. My friend Pat Krug, a marine biologist, explains the basics.

Patrick Krug, Ph.D./Professor, Cal State Los Angeles: Well, the big causes here are fresh water input, industrial pollutants that cause acid rain, fertilizer from farms getting into the ocean, but globally the biggest driver is carbon dioxide. When we drive cars and burn coal, we're putting CO₂ into the air, and a third of that gets absorbed by the oceans. Twenty-two million metric tons of carbon dioxide every day get absorbed by the ocean, and that makes the sea more acidic than it would naturally be. The ocean is more acidic now than it has been at any point in the last 2 million years.

Brand: So the increased amount of carbon dioxide in the ocean is messing with the pH of the ocean. And that can be dangerous for certain marine animals, because it makes their protective shells weaker. Davie Kline is a marine biologist at Scripps Institution of Oceanography. He's been studying ocean acidification and its effects on coral and shellfish.

Davey Kline,Ph.D./Marine Biologist, UC San Diego: The reason that you have a shell is because there's all these fish around that want to eat you. In a high CO₂ future, it's going to be harder for the shellfish to make the shells. So basically in a high CO₂ future, the shell will no longer be an effective protection against things that want to eat, like these fish.

Brand: The threat to the shell comes from changes in the ocean's carbon chemistry and strikes oysters when they're very young.

Kline: The high CO₂ makes them really susceptible and they get growth deformities. Sometimes they don't grow a shell at all, and they don't reach the point that they can use them to grow adult oysters. So it causes all sorts of problems with their development, which means that if the CO₂ levels get too high, we don't have any future generations of oysters or other shellfish.

Brand: And when it comes to endangering those "future generations," it seems that -- as in so many other things -- California leads the way.

Kline: On the west coast, we're experiencing pH levels that won't occur in other parts of the world for another 50 or 100 years. And that's why the oyster farmers in Washington and in California are already having problems today.

Dennis Peterson/Marine Biologist, Carlsbad Aquafarm: This is happening to us right now. Therefore, canary in the coal mine, it's a warning. It's a warning we should pay attention to.

That's Dennis Peterson, and he's heard the canary sing. He's the biologist at Carlsbad Aquafarm. That's about a half hour's drive north of San Diego. This seemingly peaceful little lagoon -- a quiet home to clams, mussels, and oysters -- and a bunch of pelicans -- stands right on the front lines of global climate change.

Dennis's oysters are raised from what's called seed, very young oysters just out of the larval stage. This "seed" is purchased by Carlsbad from other hatcheries and then raised into full grow oysters. But the water chemistry has changed.

Peterson: That has caused the hatcheries to have failed attempts at rearing the larvae. And with that, it's not available -- the seed is no longer available.

Brand: No seed, no harvest. Right now, Dennis is only able to get about a quarter of what he needs to fill his oyster demand. And that especially hurts this aquafarm, because oysters are 60 percent of their business. That's forced owner Norm Abell to branch out.

Norm Abell/Owner, Carlsbad Aquafarm: We're fortunate in San Diego that we can adapt in some ways by growing other things -- growing abalone, growing scallops, growing algae. But all those eventually will be effected by the water chemistry, so it's an issue that starts probably now with oysters, but it will eventually broaden out.

Brand: And local restauraunts like L&E Oyster Bar in Silver Lake are starting to feel it. They've been open for almost a year now. Since they get their oysters from lots of places, they're not really hurting for product yet. But head chef Spencer Bezaire has seen a change.

Spencer Bezaire/Chef, L&E Oyster Bar: In the beginning, it was very easy to get oysters. We could get oysters from east coast, west coast, it was never a problem. And then coming into the last few months or so, I've had farmers that were flourishing for years and then all the sudden they had to shut down for 8 months, because they couldn't keep up with -- well, the demand's higher, and obviously they couldn't supply enough seed to grow the oysters that they needed.

Brand: If you're in the retail shellfish business, this is the point where science, nature, and commerce collide, one platter at a time.

Bezaire: Well, because of the diminished supply, we obviously pay more for the product. And because we're paying more for the product, we then have to, in turn, charge more for the product to make a business.

Brand: The rate of acidification across the world's oceans is constantly in natural flux, so scientists deploy sensors like this [pictured] around the world. They measure temperature, salinity, oxygen and pH levels. Their hope is to better chart and understand the threat of excessive CO₂.

But what's a threat to some organisms is a windfall for others. Believe it or not, there's actually an upside to all this CO₂ in the ocean. And it's this -- seaweed. Stores like Whole Foods are buying as much as they can get their hands on.

Yup. Excess CO₂ -- bad for oysters but seaweed loves it, and Carlsbad is taking advantage. Owner Norm Abell looks at this new bounty with guarded optimism.

Abell: There is a little bit of a ray of hope or an exciting part. Seaweed's been eaten for two or three thousand years in certain cultures. We just have to get more people to eat their seaweed instead of their vegetables.

Brand: That might sound unappetizing at your dinner table, but like it or not, there's going to be a lot more seaweed growing in the ocean.

Krug: The natural system takes about 10,000 years for ocean buffering to change, so we've spiked CO₂ to a really high level, acidification has risen as a result of that, so any adjustment is going to play out on a scale of centuries. But if we don't do anything, the damage that we do could be irreversible.

Brand: And as for the oysters, well, you could say they're presenting us with a different and intangible sort of pearl -- a pearl of wisdom into what's happening beneath the sea.