What are the limiting survival factors of microbial life in continental terrestrial Antarctica?

Despite the extreme conditions of inland terrestrial Antarctica, life still manages to survive in microbial form. Exploring and understanding how it exists has important implications in understanding evolutionary processes, modelling early earth life and astrobiology. The most extreme environments that harbour microbial life in continental Antarctica are the Dry Valleys of the Transantarctic Mountains and the protruding Nunataks of the Ice sheet expanse. Conditions in these environments are harsh, with water in low supply, extreme temperature variation and either too much or too little sunlight. Life exists in a variety of shapes and forms. Nematodes and Tardigrades are some of the hardiest micro fauna known, able to survive total desiccation and freezing. Mosses, Algae and Lichen make up the photosynthesis capable organisms and can survive in a wide variety of environments. These organisms strive against the odds and form habitats not just in soil or on rock surfaces, but also under or within the rock. This helps to manage their moisture supply, and protect from harmful exterior forces such as extreme temperature variations and UV radiation. The major limiting forces for microbial life in terrestrial continental Antarctica are varied. Unsurprisingly water availability is the most important as it controls all organisms ability to live and grow. Temperature is also important due to its effect on the freezing point of water and controls on photosynthesis. Light plays a major part as it helps control the growth of the photosynthetic organisms as well as varies the temperature. Surface type is also important due to the slow growth rates in Antarctica, coupled with the environments required in which to survive