Nemo could get lost in acidic ocean

If you've seen the movie Finding Nemo, then you'll know that Nemo the clown fish got lost and had to try and find his way back to his home reef.

Now it seems that the Disney animators may have been onto something, because a study published in the journal PNAS led by Philip Munday from James Cook University in Queensland, Australia, found that clown fish may indeed get lost if the oceans become more acidic. And that is likely to happen as more carbon dioxide enters the atmosphere and dissolves in the seas forming carbonic acid.

Many coral reef fish spend the first few weeks of life as tiny larvae drifting through the open ocean. And previous studies have shown that they follow their noses and their ears, sniffing out and listening to sounds that lead them back to the reefs they were born on.

But, it seems that as the acidity of seawater increases, fish may loose their sense of smell and have trouble finding their way home.

Munday and his team took newly-hatched clown fish larvae and put them in choice chambers in the laboratory filled with water containing different chemicals. In seawater of normal acidity, the clownfish preferred to swim in the plume of water that smelt of rainforest trees, because in the wild they live on reefs that surround vegetated islands.

When the acidity was increased, the clown fish instead choose to swim in the plume of water that smelled of swamps, a smell they hate and usually avoid.

It may not sound like much of a difference - swamps or rainforest trees - but if wild fish start to loose their ability to find the right sort of habitat, it could spell disaster for entire populations and ecosystems.

So this study spells out yet more gloomy forecasts for the changes that might take place as carbon dioxide continues to build up in the atmosphere and even more reason to try and find ways of curbing our emissions of the greenhouse gas.