Acid eating at ocean creatures (audio)

TONY EASTLEY: Today scientists will unveil the first results of a two-year study, the most comprehensive report card of how carbon dioxide is affecting some of the planet’s most fragile marine ecosystems.

AM understands the report finds that whole marine ecosystems are at stake in the Southern Ocean and corals on the Great Barrier Reef could one day be destroyed faster than they can be created.

Here’s environment reporter Sarah Clarke.

SARAH CLARKE: It’s called ocean acidification and it’s often referred to as the evil twin of climate change.

As carbon dioxide levels increase the oceans are absorbing more.

And while that’s slowing CO2 levels in the atmosphere, it comes at a cost.

Bronte Tilbrook is from the CSIRO.

BRONTE TILBROOK: It also leads to the formation of a weak acid in the ocean which affects the carbonate chemistry.

It’s increasing the acidity of the ocean waters and that’s a concern for a lot of the organisms that live in that region.

SARAH CLARKE: The Great Barrier Reef is one region that’s been under close watch.

Scientists from the CSIRO have collected samples from the entire length of the reef, both inshore and offshore, over the last two years.

What they’ve found is it’s already under stress with the greatest impact inshore and in the southern end.

BRONTE TILBROOK: And what was surprising to us is that a lot of the waters on the reef are already in what are considered marginal growing conditions for healthy coral reefs.

That means that they probably are becoming stressed.

There is some indication that corals are not growing as well as they used to on the reef. If you make it harder for corals to grow, something else will probably take over from them.

And so the reef itself may, in 50 years’ time for example, may not look anything like we see at present – less corals, more other organisms like algae.

SARAH CLARKE: There are similar concerns further south in the cooler waters of the Southern Ocean.

Donna Roberts is the leader of the Cooperative Research Centres’ ocean acidification project.

DONNA ROBERTS: What we’ve found recently in the Southern Ocean ecosystem is that tiny marine shell-making organisms are actually getting lighter in current waters.

Pre-industrial shells are 30 to 35 per cent heavier.

And that’s because there’s not enough carbonate iron available because of the process of ocean acidification for them to actually make a robust shell.

And this has got serious implications for communities and ecosystems and things that eat them, like commercial fish.

SARAH CLARKE: That also has implications for other species in the Antarctic like whales, seals and birds.

DONNA ROBERTS: You know, we’re not talking about insignificant items in the ocean. We’re talking about the cornerstone of whole ecosystems.

SARAH CLARKE: While scientists are witnessing the most rapid responses in the Southern Ocean, they argued this is an indication of what’s in store in tropical waters elsewhere.

TONY EASTLEY: Environment reporter Sarah Clarke.

Sarah Clarke, ABC.net.au/am/, 5 April 2011. Article and Audio.


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