Exploring the viral ecology of high latitude aquatic systems

Viruses are abundant and ubiquitous in aquatic systems. While most of our knowledge in the field of aquatic viral ecology comes from the study of temperate environments, new insights are starting to emerge from polar systems. It is becoming increasingly evident that viruses play a pivotal role in structuring high latitude aquatic systems where microbes are important players and major drivers of biogeochemical cycles. In this chapter, we summarize the latest findings about the abundance, distribution and production of viruses from polar regions. We also review viral-mediated bacterial mortality and phage-host dynamics in freshwater and marine polar waters. For example, we summarize temporal studies performed in polar freshwater systems, showing a seasonal trend with a high percent of lysogenic bacteria in the winter and an undetectable rate in the summer. These findings suggest that lysogeny represents an important life strategy in polar regions. We conclude with the latest analysis of large scale meta-omics datasets, which suggest that polar viral assemblages might be a reservoir of new lineages of viruses and unknown viral diversity.