British researchers have discovered evidence of diverse life forms, dating back more than 100,000 years, in sediments of a subglacial lake on the Antarctic Peninsula.
Hodgson Lake (David A. Pearce et al).
Hodgson Lake is 305 feet deep and 1.2 miles long by 0.93 miles wide. It was covered by more than 1,300 feet of ice at the end of the last Ice Age, but is now considered to be an emerging subglacial lake, with a thin covering of just 11.5 feet of ice.
The lake was thought to be a harsh environment for any form of life but the layers of mud at the bottom of the lake represent a time capsule storing the DNA of the microbes which have lived there throughout the millennia.
Drilling through the ice the team used clean coring techniques to delve into the sediments at the bottom of Hodgson Lake.
The top few inches of cores contained current and recent organisms which inhabit the lake – two Streptomyces sp., three Sporosarcina sp. and fifteen Arthrobacter sp.
But once cores reached 10.5 feet deep the microbes found most likely date back nearly 100,000 years.
“What was surprising was the high biomass and diversity we found. This is the first time microbes have been identified living in the sediments of a subglacial Antarctic lake and indicates that life can exist and potentially thrive in environments we would consider too extreme,” said Dr David Pearce of the University of Northumbria, who is a lead author of a paper published in the journal Diversity.
This map shows the location of Hodgson Lake (David A. Pearce et al).
“The fact these organisms have survived in such a unique environment could mean they have developed in unique ways which could lead to exciting discoveries for us. This is the early stage and we now need to do more work to further investigate these life forms.”
Some of the life discovered was in the form of fossil DNA showing that many different types of bacteria live there, including a range of extremophiles which are species adapted to the most extreme environments. These use a variety of chemical methods to sustain life both with and without oxygen.
One DNA sequence was related to the most ancient organisms known on Earth and parts of the DNA in 23 per cent has not been previously described.
Many of the species are likely to be new to science making clean exploration of the remote lakes isolated under the deeper parts of the ice sheet even more pressing.
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Bibliographic information: David A. Pearce et al. 2013. Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica. Diversity, 5(3), pp. 680-702; doi:10.3390/d5030680
