The shells of some marine snails are dissolving as the seas around Antarctica become more acidic, threatening the food chain, according to a study published in the journal Nature Geoscience.
Oceans soak up about a quarter of the carbon dioxide released into the atmosphere each year; as CO2 levels in the atmosphere increase from the burning of fossil fuels, so do ocean levels, making seas more acidic. This acidification threatens coral reefs, marine ecosystems and wildlife.
The shell of the pteropod sea snail in the Southern Ocean was severely dissolved by more-acidic surface water, an international team of researchers found.
And although the snails did not necessarily die, this change increased their vulnerability to predators and infection, which could affect other parts of the food chain.
“The corrosive properties of the water caused shells of live animals to be severely dissolved, and this demonstrates how vulnerable pteropods are,” said lead author Nina Bednarsek of the National Oceanic and Atmospheric Administration. “Ocean acidification resulting from the addition of human-induced carbon dioxide contributed to this dissolution.”
The sea snails are an important source of food for fish and birds as well as an indicator of marine ecosystem health. Until now, there has been little evidence of the impact of ocean acidification on such live organisms in their natural environment, and the study supports predictions that acidification could have a significant effect on marine ecosystems.
Since the start of the Industrial Revolution, the acidity of surface ocean waters has increased by 30 percent, according to NOAA research.
If CO2 levels continue to rise, surface waters could be almost 150 percent more acidic by the end of this century, reaching a level that has not been experienced for more than 20 million years.