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The World's Sea Snails Are on Fire

Pteropods need shells, but growing them can be difficult when the oceans are full of acid.
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A healthy sea snail. (Photo: NOAA)

A healthy sea snail. (Photo: NOAA)

Pteropods are burning up. And the potential food-supply repercussions of the damage that we're inflicting on these adorable sea snails could be enough to cause acid reflux.

The shells of a little more than half of the pteropods growing close to the shoreline along the Washington-to-California coastline were found to be severely corroded. The shells of a quarter of those growing offshore from the same fog-drenched coastline had the same problem. Check out the damage we've done:


(Photo: Proceedings of the Royal Society B)

That's a microscopic picture of a corroded pteropod shell that was published last week in Proceedings of the Royal Society B—an alarming figure in a paper that cataloged the disturbing findings of an analysis of samples collected in 2011.

All over the world, but especially in some hotspots, such as the Pacific coastline (where nutrient-rich upward currents are strong), the oceans are becoming more acidic.

It's the lesser-known sibling of the main complication of global warming. Nearly 30 percent of the carbon dioxide that we pump into the atmosphere by burning fossil fuels ends up in the oceans, where it reacts with water to produce carbonic acid. The hydrogen ion concentration at the surface of the world's oceans has increased 26 percent since the Industrial Revolution, leading to a pH decline of 0.1—and a further decline of 0.3 is anticipated by century's end.

Nearly 30 percent of the carbon dioxide that we pump into the atmosphere by burning fossil fuels ends up in the oceans, where it reacts with water to produce carbonic acid.

More research is desperately needed. The Center for Biological Diversity is suing the EPA to try to force it to act under the Clean Water Act.

The problem has long been overlooked by the world's media, albeit with some impressive exceptions. But the coverage given to the new study was heartening—it was written about in newspapers and onlineoutlets. That's heartening because the problem of acid oceans might be out of sight for most of us landlubbers, but it's very much our problem.

"Pteropods are foodsource for fish, such as salmon, herring and mackerel," says Nina Bednaršek, a NOAA researcher who co-authored the new paper. Bednaršek says pteropods sometimes provide half of the diets of juvenile pink salmon. Birds and whales also feed on them.

The hope is that the tiny creatures will be able to evolve stronger shells as the water turns hostile around them. But Bednaršek says they may have just a few decades in which to do so. "The organisms might not have enough time," she says.

And if the pteropods disappear, what will feed the fish that ultimately end up on our dinner plates? Nobody knows. "We don't yet know how fish would change their diets, but it's time to start investigating this," Bednaršek says.

The food problems brought about by rising ocean acidity don't just ripple up from the bottoms of food chains. The acid levels are also killing creatures that we eat directly. An estimated 10 million farmed scallops were killed by the acidic water at Vancouver Island recently. Since 2005 oyster farmers in the same region have lost billions of their mollusks to rising acid levels.

Pass the antacid?