Ocean sciences

Marine snails found thriving in acidic seawater

Molluscs’ existence at unusually low pH suggests at least some animals will be able to tolerate seas altered by climate change.

A marine snail can withstand pH levels that are 30 times more acidic than normal seawater.

Oceans are usually around pH 8, but are expected to fall to pH 7.8 by 2100 as seas take up some of the carbon dioxide that human activities are pumping into the atmosphere. This will also reduce levels of dissolved calcium carbonate, which many sea creatures use to build their shells.

Zoë Doubleday of the University of Adelaide in Australia and her team discovered Eatoniella mortoni snails thriving at a CO2 vent 10 metres below the surface of the Pacific Ocean, where the water was pH 6.6 and had near-zero carbonate saturation.

To find out what pH conditions the snails had been exposed to throughout their lifetimes, the authors looked at a chemical fingerprint of seawater acidity in shell that had been laid down when the animals were juvenile and during adulthood. They found no difference between the two, indicating that the snails had spent their entire lives in this acidic environment.

The snails’ existence in such conditions suggests that at least some species might be able to adapt to ocean acidification, the researchers say.