Australian scientists have created a “future ocean” under the Antarctic sea ice to measure the impact of ocean acidification on seafloor communities.

The site of the experiment at O'Brien Bay near Australia's Casey station (Photo: Kristin Raw)
The site of the experiment at O'Brien Bay near Australia's Casey station (Photo: Kristin Raw)

Ocean acidification is caused by increasing amounts of atmospheric carbon dioxide (CO2) dissolving into seawater. This causes the pH of the seawater to drop and become more acidic, which affects the ability of some marine organisms, including corals and bivalves, to form shells and other hard structures. 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. The ocean is predicted to become two and a half times more acidic by 2100 under the current “business as usual” greenhouse gas emissions scenarios. The current experiment should help to understand the effects on animals living on the seafloor. A maze of ducts, tubes, thrusters and chambers have been carefully lowered through the Antarctic sea ice onto the sea floor near Australia’s Casey station as part of a world-first experiment on ocean acidification.

The ducting carrying acidified seawater to the chambers (Photo: Jonny Stark)
The ducting carrying acidified seawater to the chambers (Photo: Jonny Stark)

It has taken the team of scientists, engineers and divers several weeks to set-up the equipment for the study looking at increasing levels of carbon dioxide in seawater and its effect on sea floor plants and animals. Project Leader, Dr Jonny Stark, said it has been a challenging period with the “A factor” [Antarctic factor, ed.] blizzards, delays and technical difficulties, slowing progress. “It’s a real testament to the team’s determination and dedication that we’ve managed to get the experiment up and running despite all the difficulties Antarctica can throw at you,” Dr Stark said. “First we drilled through three meter thick, multi-year ice in O’Brien Bay to gain access to the sea floor. The divers then had to manhandle the two-meter long acrylic chambers as well as dozens of meters of pipes, tubes and thrusters through the ice and into position without disturbing the area.”

Diver ready to descend under the ice (Photo: Kristin Raw
Diver ready to descend under the ice (Photo: Kristin Raw

Seawater with elevated levels of carbon dioxide is now being pumped through the chambers and researchers are measuring any changes. “The equipment will now run continuously for eight weeks and we will focus on the areas where we expect to see the most change over this time frame,” Dr Stark said.

The ducting carrying acidified seawater to the chambers (Photo: Jonny Stark)
The ducting carrying acidified seawater to the chambers (Photo: Jonny Stark)

Source: Australian Antarctic Division (AAD)