Microbial ecology of Antarctic aquatic systems

The application of 'omic' approaches (for example, pyrosequencing, metagenomics, metatranscriptomics and metaproteomics) has generated unprecedented insight into Antarctic microorganisms and revealed intriguing properties about communities that can be linked to their Antarctic-specific habitats.Community composition and ecosystem function are controlled by the polar light regime, biotic and abiotic environmental factors, limnological history and seed populations, biogeography and the limits of aeolian and advective dispersal caused by physical barriers and distance between sites, and perturbation caused by ecosystem change.The polar austral summer is characterized by continuous high solar irradiance, which stimulates phototrophic growth and kinetically accelerates growth. Such communities tend to be oriented towards maximizing the effectiveness of light energy while switching to light-independent processes (for example, chemolithoautotrophy, phagotrophy and heterotrophic utilization of storage compounds) to survive the cold, dark winter.Virus–host interactions are particularly important in the Antarctic food web, in which they not only control remineralization and influence community composition but have unanticipated roles in influencing productivity cycles. Discoveries pertaining to viruses have included systems with a high diversity of novel eukaryotic viruses, phage-resistant bacteria, and archaea capable of evading, defending against and adapting to viruses.Unusual biogeochemical cycles have developed as a result of communities evolving in very specific, local environments. The indigenous communities have developed a range of traits, including a hierarchical structure, low complexity, niche adaptation, clonal dominance, mixotrophy and short-circuited nutrient cycles that enhance the use and conservation of resources.Specific taxa have a major influence on overall ecosystem function, with stability of those biomes being reliant on the key, specialized and fit members maintaining function and not being affected by ecosystem perturbation, particularly anthropocentric climate change and the introduction of alien species.