| Summary: | The polar regions suffer from extreme environmental conditions such as low temperatures, freezing-thawing cycli, high UV-irradiation, desiccation and varying light conditions, salinities and nutrient concentrations, and as such these areas are some of the most inhospitable places on earth. However, the poles harbour a wide variety of different terrestrial and aquatic biotopes ranging from the surrounding oceans, sea-ice and marine sediments to continental lakes, the ice sheet, soils and rocks, where microorganisms are the most abundant and often the only form of life. Antarctica is characterised by its geographical and climatic isolation and most of the continent is covered by ice. However, desert like ice-free areas exist, often located near the costs and in these areas the Antarctic lakes are situated. Most of the Antarctic non-marine biomass is found in the lakes, which are dominated by a planktonic microbial loop community and benthic microbial mats. Polar oceans are cold and oligotrophic habitats, where most of the microorganisms are found in the water column and in sediments. The annual cycle of sea-ice formation and melting, the exclusion of salts
|
|---|