Dissolving Sea Snails!

This story speaks for itself, so I will keep my commentary to a minimum. This text is from Science Daily's First Evidence of Ocean Acidification Affecting Live Marine Creatures in the Southern Ocean.

The shells of marine snails — known as pteropods — living in the seas around Antarctica are being dissolved by ocean acidification according to a new study published this week in the journal Nature Geoscience. These tiny animals are a valuable food source for fish and birds and play an important role in the oceanic carbon cycle.

During a science cruise in 2008, researchers from British Antarctic Survey (BAS) and the University of East Anglia (UEA), in collaboration with colleagues from the US Woods Hole Oceanographic Institution and the National Oceanic and Atmospheric Administration (NOAA), discovered severe dissolution of the shells of living pteropods in Southern Ocean waters.

The team examined an area of upwelling, where winds cause cold water to be pushed upwards from the deep to the surface of the ocean. Upwelled water is usually more corrosive to a particular type of calcium carbonate (aragonite) that pteropods use to build their shells. The team found that as a result of the additional influence of ocean acidification, this corrosive water severely dissolved the shells of pteropods.

Ocean acidification is caused by the uptake of carbon dioxide from the atmosphere emitted as a result of fossil fuel burning. A number of laboratory experiments have demonstrated the potential effect of ocean acidification on marine organisms. However, to date, there has been little evidence of such impacts occurring to live specimens in their natural environment. The finding supports predictions that the impact of ocean acidification on marine ecosystems and food webs may be significant.

In short, what had been previously demonstrated only in the laboratory has now been found in the Southern Ocean. The importance of this finding can not be overstated.

Here's the abstract for the Nature Geoscience paper Extensive dissolution of live pteropods in the Southern Ocean.

The carbonate chemistry of the surface ocean is rapidly changing with ocean acidification, a result of human activities. In the upper layers of the Southern Ocean, aragonite—a metastable form of calcium carbonate with rapid dissolution kinetics—may become undersaturated by 2050.

Aragonite undersaturation is likely to affect aragonite-shelled organisms, which can dominate surface water communities in polar regions. Here we present analyses of specimens of the pteropod Limacina helicina antarctica that were extracted live from the Southern Ocean early in 2008.

We sampled from the top 200 m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO₂. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94–1.12 produces equivalent levels of dissolution.

As deep-water upwelling and CO₂ absorption by surface waters is likely to increase as a result of human activities, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand.

The "Other" Carbon Problem — Ocean Acidification (August 17, 2010)
Acidifying The World's Oceans (February 23, 2012)
The Coming Mass Extinction In The Oceans (August 24, 2012)
There Go The Coral Reefs (June 11, 2012)
A Mass Extinction In The Oceans (June 22, 2011)

Bonus Video — The Acid Test: The Global Challenge of Ocean Acidification (from NRDC, 21:35)