Steve
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Life in the Dry Antarctic Valleys
 
Bull Pass Photograph by: Josh Landis, National Science Foundation

There is a series of dry valleys in Antarctica.  These are in the McMurdo Sound and Victoria Land.  There is very little snowfall and no rain.  These valleys are subject to katabatic winds of up to 200 miles an hour (320 Kilometres an hour.)  The average temperature is about minus 20 degrees C (minus 4 degrees F.)  These are very similar to the conditions used in a laboratory for freeze drying samples.  The highest air temperature is about 0 degrees C (32 degrees F.)

When these valleys were discovered they were considered to be completely devoid of life.  However, now they are being increasingly studied and more and more living organisms are being discovered.

Bacteria

The valley soils, despite their apparent extreme dryness are home to bacteria of several different groups including Deinococcus, Rubrobacter, Acidobacteria and Actinobacteria.

There are several other groups of organisms including yeasts.

Photosynthesis

The valley rocks include sandstone which has photosynthetic organisms near the surface where there is enough light penetration, but also protection from the rock itself.

The top 2 millimetres has lichen, which is a symbiotic relationship between a fungus and a green alga.  A little deeper in the rock are blue green algae, especially Chroococcidiopsis which is known for its high resistance to radiation.  Apparently, although these blue green algae grow in low light conditions, light is not as much a limiting factor as shortage of Carbon dioxide.

 

Under the Rocks

Although there is very little light under the rocks, another group of Blue-Green Algae are living there.

Multicellular Organisms

At least three different groups of multicellular organisms live in the dry valleys.  These are Nematodes, Rotifers and Tardigrades. Tardigrades also have the distinction of having survived the vacuum of space for ten days, as well as having high resistance to radiation.

Comparison with Mars

The conditions in the dry valleys are the closest Earth gets to the conditions of Mars.   Like Mars, the area is blasted by wind blown sand grains.  It is actually slightly colder than Mars is at the equator.  One obvious difference is the atmosphere, but this would mostly be a problem to the animals rather than the plants because Mars has enough Carbon dioxide in its atmosphere.

Curiously, when I was at school, we were taught that Mars would have plants like Lichen.  Although no sign has been found of these yet, it should be remembered that when they were first explored, Antarctica’s dry valleys were thought to be completely sterile.  The surprisingly rich ecology was completely missed by people actually there, not relying on robots working at interplanetary distances.

We cannot rule out similar organisms on Mars.