Antarctic bottom water (AABW), which is dense and cold, was known to originate from three sources. For more than 30 years, scientists have speculated the location of a fourth undiscovered source of AABW.
IMOS observations from seals have contributed to the discovery of a fourth stream coming from the intense sea ice formation in the Cape Darnley Polynya, north west of the Amery Ice Shelf.
The research has been published in the Nature Geoscience journal.
Co-lead author Dr Guy Williams, a sea-ice specialist at the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) in Hobart said that the seals provided integral information.
“The seals went to an area of the coastline that no ship was ever going to get to, particularly in the middle of winter, and measured the most extreme dense shelf water anywhere around Antarctica.
“Several of the seals foraged on the continental slope as far down as 1800m, punching through into a layer of this dense water cascading down to the abyss.
“They gave us very rare and valuable wintertime measurements of this process,” he said.
The tagged seals relay information via satellite as they surface. The observations are collected by IMOS, which makes the data publicly available for use by Australian scientists and their international collaborators.
IMOS Director Mr Tim Moltmann said that this is a great example of the benefit Australia derives from having an integrated marine observing system that makes all of its data available.
“We funded the tagging of these seals to address completely different scientific objectives. However, Dr Williams and his colleagues were able to access and reuse the data in their work, and it’s contributed to a very significant discovery,” he said.
ACE CRC CEO Tony Press said the research demonstrates the important role that IMOS plays in the broad ocean sciences community.
“Data made publicly available in real or near-real time can be used by scientists outside that particular research project. Here is an excellent example of the serendipity that can result – a breakthrough in solving an difficult oceanography puzzle using data derived from a research project on seal ecology.”
The findings of this research open the door for further discoveries of AABW production from the other polynya regions around the Antarctic coastline.