National Geographic News
Photo of a dissolving pteropod.

This sea butterfly, a type of marine snail, shows damage to its shell (jagged line radiating from center) due to acidic ocean waters.

Photograph by Steve Ringman, NOAA

Jane J. Lee

National Geographic

Published May 2, 2014

Ocean acidification isn't proceeding at a snail's pace, says new research.

The study finds that corrosive water off the U.S. West Coast is dissolving the shells of a marine snail, also known as a sea butterfly, that is a key player in the coastal food chain.

Researchers worry that the mollusks' weakened shells could have far-reaching consequences for the animals that eat them, such as fish and marine mammals.

Salmon, herring, and other commercially important species rely on a snail-rich diet. But with many sea butterflies now growing thin, pitted, bumpy shells—a clear sign of ocean acidification—their ability to reproduce, protect against infection, and even swim is being compromised.

"We've been talking about ocean acidification as a problem for the future," says Scott Doney, an oceanographer with the Woods Hole Oceanographic Institution (WHOI) in Massachusetts, who was not involved in the study. But this research, he says, shows that it's already an issue. (Read about ocean acidification in National Geographic magazine.)

Graphic explaining ocean acidification.

Damaged Protection

A team led by Nina Bednaršek and Richard Feely of the U.S. National Oceanic and Atmospheric Administration (NOAA) found that between 24 and 53 percent of the sea butterflies they studied in 2011 off the Washington, Oregon, and California coasts showed signs of severe shell damage.

Most of the injured animals were found closer to shore, where waters are most acidic due to high concentrations of carbon dioxide from the burning of fossil fuels. A natural phenomenon called upwelling—a seasonal event on the West Coast in which deep-water nutrients and carbon dioxide rise to the surface—compounds the problem.

Lab studies have repeatedly shown that sea butterflies struggle to build shells in acidic waters, says Bednaršek.

But now, says Feely, "we see for the first time a clear indication of the effects of ocean acidification on a critical marine organism [in the wild]."

Photo of a healty pteropod.
A sea butterfly with a healthy shell.
Photograph by Nina Bednarsek, NOAA

An Uncertain Future

WHOI's Doney says Bednaršek and Feely's work, published this week in the journal Proceedings of the Royal Society B, raises a lot of questions. For instance, while it's clear these snails are being affected, it's not clear exactly how their deterioration will affect the food chain.

In any event, says Doney, the problem is going to only get worse. Bednaršek and colleagues predict that by 2050, about 70 percent of West Coast sea butterflies could have severely damaged shells.

The only clear fix? Doney says that would be to reduce carbon emissions. But, he adds, "that's a much more difficult problem."

Follow Jane J. Lee on Twitter.

Surreal Artist
Surreal Artist

You guys do realize, we're just waiting for humans to destroy everything. The best answer is that something comes along and wipes us all out. No offense to the nice people, but we are to blame so we need to eradicate ourselves to restore order.. We are a disgusting race and we have made everything wrong and full of chemicals/toxins.

ideogram tianya
ideogram tianya


martin a
martin a

them pics though, such a booty

king regards martin a


Thanks to environmentalists actions, the depletion of corals and such other CaCO3  producing shell fish and the like though endangered are somehow getting a boost to get re-energized. So let us all hope for the best and try our best to help our environment . 

Deepa Nhattiala
Deepa Nhattiala

To reduce carbon emission is indeed a much difficult problem. What with the exponential increase in the use of petrol and diesel. This article could have included few tips to what we can do individually to minimise carbon foot print.

Newwayy Liu
Newwayy Liu

Beautiful things arouse peoples attention.

M. Linde
M. Linde

Realmente produce mucha tristeza darse cuenta de como el hombre ha deteriorado el medioambiente.No solamente estas criaturas se irán perdiendo,la Barrera de Coral se ha ido deteriorando aceleradamente. Y como bien dice en este artículo,en el caso de los 'sea butterfly', aún no se sabe como puede incidir en la cadena alimenticia y eso es preocupante de veras.

Half Rock
Half Rock

Interesting article it has next to nothing to do with CAGW and CO2.

It is quite possible to have local reduction in the basic PH. However this is a phenomena not related to the world's oceans. AnD does not prove that slightly less basic is the actual reason for the erosion of the shells. There  are other reasons why organisms can have trouble precipitating CaCO3.

The Oceans are basic. About 8.2 on the PH scale. There are huge buffers CO2 is in equilibrium with the oceans and (Ohmoto,1986) The partition coefficient is 50:1, Revell Suess 1957, Skirnor 1975. If you double CO2 you would have to supply 50 times as much Co2 to the oceans to get chemical equilibrium. 51 times is more than all of the known fossil carbon. If you could burn 7000GT at the present temperature and atmospheric pressure given the buffering the most you could increase .the atmospheric CO2 given adequate mixing which is decadal Druffel& Williams 1990 and is adequate to buffer the amount  Jaworoski et Al 1992.

Ok so that is some of thee science. How do we test the conclusions of the chemical formulas, that only look at a miniscule amount of the additional pot\\al buffering like metals and platy minerals,  We have to look at what has been documented from the past geologic record  that the organisms evolved in a period when the earth's atmosphere contained enormously more CO2.. If they all disl0ved why are they here now? 

This is more than a hypothetical question it is based upon the chemical reactions , buffering and shows that even at that level of CO2 the organisms that precipitate CaC03  survive in a safely buffered ocean, This is an acceptable scientific method observation which is very hard to falsify.

So I am just thinkin'

We should take a deep breath and not feel o bad about the CO2 we exhale. Simple chemistry says you'll be vindicated.

Avraam Dectis
Avraam Dectis


   This can be reversed by dumping large quantities of lime into the oceans.

     Now might be a good time to start.


jeffrey guy
jeffrey guy

Talk is great, let our conversation continue. I implore all who are concerned to act TODAY! The time for debating has long ago passed us by. Solar energizing is up and ready to surge. Thankfully groups the world over are implementing solar power every day. The benefits are huge, both to our future and the present economy. WE need jobs, purpose, and by the way we still need our ecosystem and the life forms that depend on us not making the environment too toxic from top to bottom. TODAY please care , please show your wisdom and leadership, get informed and join in efforts to mitigate our impacts.

Adam Meyer
Adam Meyer

Could this acidification be the same thing that's affecting the sea stars (starfish) there on the west coast, too?

Giovanni Rantucci
Giovanni Rantucci

In the end reduction of Carbon emissions is the major problem of our society! 

Barbara R.
Barbara R.

How many of these stories are we to hear before we get the warning and do something, immediately. Or are we just gonna wait until it is so badly ruined that we can no longer sustain ourselves? There are so many simple things to do in our own homes to severly cut our effect on the earth. I live in town and grow all my fruits and vegetables for my family, no till, no water, no chemicals, and I harbor a good winter in the North. It just takes a little bit of effort, and this is just one tiny thing to help the earth.  I guess we will just debate ourselves to extinction.


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