This book provides a structured account of the full range of environments in Antarctica and of the microbial communities that live within them. Environments examined include: snow and ice; benthic marine; sea ice; lakes and streams; marginal ice; soil; the open ocean; rock. In the more extreme habitats of this region microscopic life forms constitute the entire biology of the habitat, but in all antarctic environments the microbial communities play a major and often dominant role in the transfer of carbon, nutrients and energy throughout the ecosystem. The book examines the major features of the chemical and physical environment in each habitat, and the influence of these features on the population structure and dynamics of their microbiota.