Cyanobacteria in the Cryosphere: Snow, Ice and Extreme Cold

This chapter explores the occurrence and dominance of cyanobacteria in some of the harshest environments on earth, the cryosphere, where extreme cold and the near absence of liquid water provide severe constraints on growth and survival. They are present in ice-based ecosystems including snow, glacier ice, lake ice and ice-shelves, and sometimes achieve remarkably high biomass concentrations. Cold desert ecosystems in the Arctic and Antarctica also contain a variety of habitats colonized by cyanobacteria, although their diversity is low, and similar taxa are present in different geographic locations under similar ecological conditions. The strategy for microbial success in these environments is not adaptation towards optimal growth at low temperatures, but instead rests on tolerance to environmental extremes. An ability to survive prolonged dormancy is also an important feature accounting for the widespread occurrence of cyanobacteria in these environments.