Study: Our Oceans Are So Acidic They're Dissolving Snails

Consequences attributed to our reliance on fossil fuels occurring in the Antarctic Ocean

The pteropod (marine snail) Limacina helicina antarctica (Nina Bednarsek/British Antarctic Survey)

PROBLEM: In 2008, a U.S. scientist predicted the corrosive effects that ocean acidification could have on tiny shellfish called pteropods, also known as marine snails, also known as sea butterflies, and sometimes referred to as "the potato chips of the oceans." She warned they would not only be the "canaries in the coal mine" of climate change, but that the impact of losing a snail the size of a lentil would undoubtedly creep its way up the food chain.

METHODOLOGY: Turns out, this hypothetical disaster was already happening. Also in 2008, during what should have been a relaxing trip in the Antarctic seas (or at least, that's what the phrase "science cruise" evokes for me), researchers from British Antarctic Survey, the University of East Anglia, the US Woods Hole Oceanographic Institution, and the National oceanic and Atmospheric Administration collected pteropods from the top 200m of the ocean's surface, where they tend to live, and examined them for shell damage.

RESULTS: The sea snail's shells were found to be "severely dissolved."

Part of the acidity in the water sample was due to upswelling, a natural occurrence in which cold water from the depths of the ocean is pushed up to the surface by heavy winds. Upwelled water itself can be corrosive, and it's expected to occur more frequently as climate change intensifies. But the ocean's pH is also decreasing at least in part because of atmospheric carbon dioxide attributed to the burning of fossil fuels.

The researchers put together a video of combined SEM images of their specimens, which illustrates what the increasing degrees of corrosion look like:

Zoomed out, it's the difference between this:


© 2012 Macmillan Publishers Limited

And this:


© 2012 Macmillan Publishers Limited

CONCLUSION: The impact of ocean acidification is, as predicted, significant, and is affecting marine ecosystems and food systems.

IMPLICATIONS: "The tiny snails do not necessarily die as a result of their shells dissolving," said co-author (and science cruise leader) Geraint Tarling, "however it may increase their vulnerability to predation and infection." This can go on to affect bigger fish, and from there, penguins and polar bears. The snails are also the only food source of the "Sea Angel," another pretty name for something that's really just a slug, but is no less important for it. And these little guys are only the first to start dissolving -- if ocean acidification continues at its current rate, the consequences can extend even further. First it's the sea butterflies, then it's everything else.

The full study, "Extensive dissolution of live pteropods in the Southern Ocean," is published in the journal Nature Geoscience.