Australian scientists are helping probe the ocean's enigmatic 'twilight zone' which is home to strange creatures and crucial in the process of capturing carbon.
Twenty researchers returned to Hobart on Friday after a six-week mission in the Southern Ocean on the RSV Investigator ship.
They deployed a suite of sensors, instruments and robotic floats at three locations to investigate the role ocean life plays in capturing atmospheric carbon.
"The ocean has actually been doing us a big favour over the last couple of centuries," voyage chief scientist Professor Philip Boyd told reporters.
"The trees on land store carbon through photosynthesis. In the ocean it's a slightly different process.
"We have these microscopic plants called phytoplankton. Because of the huge surface area of the ocean they take up huge amounts of carbon.
"Some of it sinks to depths as marine snow, taking carbon out of circulation for centuries or longer."
Scientists want to get a better understanding of how much carbon the ocean captures and how climate change may be impacting the process.
They are examining the so-called 'twilight zone', the region where sunlight stops penetrating the water.
"A lot of creatures, they like to hang out there because it feels safe and secure," Prof Boyd said.
"But it is a difficult place to sample. We actually know more about the sea floor and about the surface of the ocean than we know about the twilight zone.
"It's a place where a lot of carbon is transformed."
Robots deployed in Southern Ocean will spend four years transmitting data via satellite.
Prof Boyd said it was the first voyage of its kind to bring together ship-board ocean measurements, biological sampling, deep-diving robots, automated ocean gliders and satellite observations.
"We set out with ambitious science objectives for this voyage, and we could not be happier with the outcome," he said.
Australian Associated Press
