Divers prepare to enter the chilly Antarctic waters
Divers prepare to enter the chilly Antarctic waters (Photo: Glenn Johnstone)
Dive team on the sea iceThe experimental chamber on the seafloorThe seafloor habitat in O'Brien BayExperiment site at O'Brien Bay, near Australia's Casey stationDigging a hole through the sea ice in O'Brien BayDiagram of the future ocean experiment

For the first time Australian scientists will create a “future ocean” under the Antarctic sea ice this summer to measure the impact of ocean acidification on seafloor communities.

The team of scientists, engineers and specialist divers will deploy four acrylic chambers 10–20 metres beneath the sea ice near Casey station between November and March 2015.

Australian Antarctic Division Marine Ecologist and Project Leader, Dr Jonny Stark, said the researchers will increase the level of acidity in the two metre long chambers to mimic the ocean conditions predicted within this century.

“When carbon dioxide dissolves from the atmosphere into the ocean, the seawater becomes more acidic, affecting the ability of marine organisms, such as single-celled algae, corals and bivalves, to function and develop normally,” Dr Stark said.

Currently the Southern Ocean absorbs 40% of the global ocean uptake of carbon dioxide and polar waters are acidifying at twice the rate of tropical waters.

Under the current ‘business as usual’ emissions scenario, the ocean is predicted to become two and half times more acidic by 2100.

“This research will give us a window into the future,” Dr Stark said.

“We will be able to detect any changes in the seafloor community over the four month study, see what happens to the animals and plants and how the chemistry of the seawater and seabed sediments change.”

The experimental chambers will be fitted with underwater flow meters, thrusters, pH and temperature sensors and time-lapse cameras, which will record all the changes in the environment.

A complex system of pipes and pumps will work 24 hours a day to draw the seawater to the surface, where it will be enriched with carbon dioxide, before being pumped back down under the sea ice and into the chambers.

The chambers will be deployed through the metre thick sea ice in O’Brien Bay and divers will anchor the chambers to the seafloor.

“While the divers will be wearing dry suits, one of the biggest challenges will be the frigid −1.8°C water temperature,” Dr Stark said.

“The human body can only handle those sorts of temperatures for about an hour, so we will be constantly monitoring and swapping out the divers.”

Some of the team members flew to Antarctica late last week, ahead of the official start to the 2014–15 season today, with Australia’s research and resupply ship, Aurora Australis, departing Hobart for Davis station.

Australian Antarctic Division Operations Manager, Robb Clifton, said the current sea ice conditions in East Antarctica are challenging.

“We are monitoring the situation closely as recent satellite imagery shows extensive sea ice around Davis station, but we won’t know how thick it is until we get there,” Mr Clifton said.

“Like all our voyage plans we have contingencies in place for refuelling and resupplying the station if we are delayed in reaching it.”

80 expeditioners are heading south on this voyage, which is expected to return at the end of November.

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