Australian scientists studying the effects of ocean acidification on marine life

Chambers are being set up by Australian scientists under Antarctic sea ice to test the impact of ocean acidification on marine life.

The big acrylic boxes will be fed with seawater enriched with carbon dioxide to show the disruption by acidification that this sea life should expect over the century, according to the Australian Antarctic Division.

Ocean acidification is being caused by the uptake of human-produced excess carbon dioxide into the global seas.

Acidification will cost the world economy more than $US1 trillion annually by 2100 if not curbed, according to a report to the UN Convention on Biological Diversity, released this month.

Widespread effects of acidification, mostly bad, were “nearly inevitable”, the report said.

Polar waters are acidifying at twice the rate of tropical waters, with carbon dioxide levels predicted to more than double from 397 parts per million to 940 ppm by 2100 under a “business as usual” scenario.

To study its effects in Antarctica, a research team led by marine ecologist Jonny Stark will set up four chambers on the sea floor near Casey station, about 3400 kilometres south-west of Hobart.

Dry-suited divers will work in the minus 1.8 degrees water to install the two-metre long chambers, and a complex system of pipes and pumps, together with time-lapse cameras to record changes.

Dr Stark said marine life such as urchins, starfish, shellfish and lace corals would be enclosed, together with algae and seaweeds. The more acidic 940 ppm water will be pumped through two boxes to mimic the predicted increases.

Another two enclosures would be pumped with normal water to act as scientific controls for the experiment.

Open ocean swimming krill at the centre of the Antarctic food web are not expected to be included, and Dr Stark said fish would be kept out.  “If we enclosed them, they might eat everything that’s there.”

Among the life to be studied, small filter feeders that build calcium carbonate shells are expected to do poorly with acidification, but some predictions said the algae would flourish in a sea with enhanced carbon dioxide.

The four-month experiment, conducted in collaboration with the US Monterey Bay Aquarium, is not expected to directly show the decade-on-decade evolutionary changes to life predicted for acidification.

But Dr Stark said it would give a clear indication of acidification’s effects. “The benthic seabed is really important to understand. We expect to see who will be the winners and who will lose.”

Andrew Darby, The Sydney Morning Herald, 23 October 2014. Article.

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