Abstract: 

Marine viruses have important roles in microbial mortality, gene transfer, metabolic reprogramming and biogeochemical cycling.  However, methodological limitations have previously prevented a quantitative assessment of their community structure and ecosystem impacts.  Recent transformative advances have led to construction of a sample-to-sequence pipeline that enables a quantitative assessment of marine viral communities using metagenomic techniques, and has facilitated a rapid increase in knowledge of marine viral ecology and their impacts on oceanic ecosystem function.  Here I focus on recent studies that have greatly advanced our knowledge of marine viruses, including (i) a global-scale assessment of marine viral community structure and the factors that drive this variability, (ii) a study that connects this global-scale viral metagenomic data to the roles of viruses in the oceanic carbon cycle, and (iii) further methodological advances, including bioinformatic approaches and metaproteomics, that are enabling us to illuminate both taxonomic and functional viral ‘dark matter’ that dominates environmental viral metagenomes.