[ASC-media] Life beneath the sheets: 9000 years in the dark

Niall Byrne niall at scienceinpublic.com.au
Tue Jul 28 03:42:51 CEST 2009

Researchers at Geoscience Australia have unravelled the development of a
unique seafloor community thriving in complete darkness below the giant
ice sheets of Antarctica.

The community beneath the Amery Ice Shelf in Antarctica is 100 km from
open water and hidden from view by ice half a kilometre thick. This
ecosystem has developed very slowly over the past 9000 years, since the
end of the last glaciation. Today it is home to animals such as sponges
and bryozoans fed by plankton carried in on the current. 

During the summer of 2003-2004, six scientists and technicians from the
Australian Antarctic Division (AAD) spent a month on the Amery Ice Shelf
in east Antarctica and obtained sediment samples from beneath ice half a
kilometre thick.  

Researchers from Geoscience Australia, working in collaboration with the
AAD, studied the sediment samples to determine their age and to look for
clues to changes in the environment over time. When Geoscience Australia
geologist Dr Alix Post studied the shell fossils within the core
samples, she unexpectedly found evidence of ancient ecosystems.  

"The last Ice Age peaked 18,000 years ago. At that time there would have
been little or no life under the ice. This was the first core of
geologically recent sediment ever collected beneath an ice shelf. By
analysing sediment samples of the community, we were able to look at how
species gradually replace each other over time," says Alix.

 "Our analysis of the fossils within the sediments shows that as the ice
receded, the first animals reached this site 9000 years ago," Alix says.
"They were small mobile scavengers which would have been swept in via
bottom currents from open waters, and were able to burrow and crawl for

"In the following few thousand years, filter feeders, such as sponges
and bryozoans colonised the area and were maintained by a constant
supply of oxygen and food. This type of the species succession
demonstrates the constant struggle for life beneath the ice shelf," says

"Studying habitats such as these can help to improve our understanding
about changes in species diversity over time, and allow us insight into
how ecosystems are able to survive and prosper in such hostile
environments. It could help us understand the potential effects of
climate change on Antarctica," she says. 

Researchers from Hamilton College, New York, documented changes in
another Antarctic ecosystem following the collapse of the Larsen B ice
shelf in 2002.

The sediments Alix studied were collected by a team of scientists and
technicians from the AAD, led by Ian Allison and Mike Craven.

Her work was published in History of benthic colonisation beneath the
Amery Ice Shelf, East Antarctica. Marine Ecology Progress Series, 344 pp

Alix Post is one of 15 early-career scientists presenting their research
to the public for the first time thanks to Fresh Science, a national
program sponsored by the Australian Government. 

For further information, please contact the Geoscience Australia 24/7
Media Hotline 1800 882 035.

For Fresh Science contact: Sarah Brooker on 0413 332 489 and Niall Byrne
on 0417 131 977 or niall at freshscience.org
<mailto:niall at freshscience.org> .

Further details at www.freshscience.org.au

And background information at www.aad.gov.au/default.asp?casid=20367





Niall Byrne


Science in Public

26 Railway Street South, Altona Vic 3018


ph +61 (3) 9398 1416 or 0417 131 977

niall at scienceinpublic.com.au <mailto:niall at scienceinpublic.com.au> 


Full contact details at www.scienceinpublic.com


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