Special chambers simulate ocean acidification in Antarctica (text & audio)

BRENDAN TREMBATH: Scientists from the Australian Antarctic Division have built special underwater chambers to test what will happen when the ocean becomes more acidic. Increases in carbon dioxide in the atmosphere are absorbed by the ocean, making sea water more acidic. The experiment being conducted under the sea ice at Casey station this summer is designed to show what effect acidification will have on marine life in the next 100 years.

Felicity Ogilvie reports from Hobart.

FELICITY OGILVIE: Scientists have placed four coffee table-sized chambers on the sea floor near Casey station. Two of the chambers contain regular sea water. Carbon dioxide is being pumped inside the other two containers, simulating ocean acidification. The project leader is Dr Jonny Stark.

JONNY STARK: So this change in acidity potentially has very serious consequences for all marine life. It will potentially affect everything from growth, reproduction, physiology, as well as more indirect effects, like effects on food webs, food chains. So, if it doesn’t affect something directly through its growth or reproduction, it might affect whole food webs and the very nature of life in the ocean. In particular, it’s going to affect animals that form shells.

FELICITY OGILVIE: Dr Stark says the experiment is designed to show what the sea floor will look like in 100 years’ time, when ocean acidification takes effect.

JONNY STARK: Under a business-as-usual emissions scenario, the predictions are fairly clear about what kind of changes we might see. So we’re using that business-as-usual, which is kind of doing what we’re doing now, emissions sort of staying fairly similar to what they are now, what kind of changes we might expect to see in the ocean. Of course, if we get our act together, and actually do something more proactive, and really do curb carbon dioxide emissions, they might not be as severe. If we don’t, they certainly will be what we’re simulating in this experiment, and possibly even worse.

FELICITY OGILVIE: At the moment, the marine life on the sea floor near Casey station is vibrant. The field project manager Dr Glenn Johnstone is speaking from Antarctica, where he has been diving down to take samples from the chambers.

GLENN JOHNSTONE: Certainly under the sea ice, where we’re diving, you’re looking at a fairly stable temperature regime, and that’s mostly we’re talking about sort of -1.8 degrees constantly throughout the year.

FELICITY OGILVIE: And what is the environment like there under the sea floor where you’re doing this experiment on ocean acidification? What lives there and what does it look like?

JONNY STARK: Well, it’s surprisingly diverse and colourful. It’s not something that most people expect when they think of the under-ice environment in Antarctica. Above the sea ice, Antarctica is fairly bleak in that there is a lot of ice, there’s some rock, and that’s about it. And every now and again, you’ve got some penguin colonies, some sea birds, but really there isn’t a lot happening above the sea ice. Below the sea ice, living on the sea floor are all of these animals that you would probably expect to see and recognise from a reef in Tasmania, or anywhere around Australia. So you’ve got starfish, sea anemones, sea urchins, and then a whole variety of different worm species, sponge species – a great variety and very colourful sponge species. And then in the sediment itself, in the mud and sands, there’s a whole another diversity of very tiny animals that live in there, and they’re one of the main focuses of our experiment. And they’re one of the main ways that we monitor the health of the environment.

FELICITY OGILVIE: The experiment will finish in March, and the scientists expect to get their first results back later this year.

Story reported by Felicity Ogilvie, PM / ABC News, 22 January 2015. Text & audio.

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