KEY POINTS:
Two New Zealand scientists return today from -40C temperatures in Antarctica, where they braved the frozen darkness of approaching winter to study ancient life forms.
Ian Hawes and Karl Safi have spent the past eight weeks camping 3500km south of New Zealand, on the McMurdo ice shelf, to study organisms which have evolved to tolerate the winter freeze.
The men camped on the edge of Bratina Island where it joins the ice shelf, 35km from New Zealand's Scott Base.
They slept in tents - where their body condensation froze inside their sleeping bags - and used portable huts as makeshift laboratories.
They tracked changes in the biological, physical, and chemical processes of micro-organisms in nearby ponds that go through annual freeze-thaw cycles.
The pond life is dominated by dense mats of blue-green algae, which National Institute of Water and Atmospheric Research (Niwa) scientist Brian Sorrell described as "remarkably adaptable" organisms that were the earliest and simplest of Earth's lifeforms.
"They evolved some three billion years ago and are the only organisms that can cope with the extreme conditions," said Dr Sorrell, who is leading the project and spent January at the ponds with Dr Hawes and another Niwa scientist, Dave Arscott.
It is thought the multi-layer mats create relatively benign micro-habitats, with copious production of mucilage that helps protect the organisms from damage during freezing and desiccation.
The algal mats may be similar to fossils from before global glaciation - known as Snowball Earth - which froze even the tropics about 500 million years ago.
Repeated samples of the micro-organisms and fine-scale measurements of the pondwater recorded changes in species composition, biomass, rates of photosynthesis, and the chemical and physical environment as temperatures and light levels fell and the ponds froze.
The ponds began to freeze in early February, and the ice thickened as air temperatures plunged to -40C by early last month.
The two scientists are flying out with 20 American researchers running a similar study in larger lakes of the McMurdo Dry Valleys.
Most researchers leave at the end of the Antarctic summer in mid-February but extra research funding in the International Polar Year has paid for a late-season flight, provided by Antarctica New Zealand and the US National Science Foundation.
- NZPA
