26 Nov 2012: Snails in Southern Ocean
Showing Effects of Ocean Acidification

The shells of some sea snails in the Southern Ocean are already dissolving as a result of ocean acidification, according to a new study. In an analysis of free-swimming pteperods collected from Antarctic waters in 2008, scientists found that the outer layers of the animals’ shells showed signs of unusual corrosion, potential evidence that ocean acidification caused by excess carbon dioxide in the atmosphere may already be disturbing vulnerable marine species. Laboratory tests have shown that acidic water threatens many invertebrate marine species, such as clams and corals, since it hinders their ability to grow shells and exoskeletons. The most vulnerable species are those, like pteropods, that build their shells from aragonite, a form of calcium carbonate that is sensitive to increased acidity. “The corrosive properties of the water caused shells of live animals to be severely dissolved and this demonstrates how vulnerable pteropods are,” Nina Bednaršek, a scientist at the U.S. National Oceanic and Atmospheric Administration (NOAA) and lead author of the study, published in the journal Nature Geoscience, told Reuters. According to scientists, pH levels in the oceans are dropping faster than during any period over the last 300 million years.