You can find viruses everywhere: in the soil, in the clouds and in animals. According to scientists from the University of Oldenburg in Germany, there are also a ridiculous number of viruses buried at sea, in the sediments of the oceans.
These sedimentary viruses don’t lie dormant on the seabed, but actively replicate down in the fathoms, even in the gyres of the ocean where most forms of life can’t be sustained since organic carbon is a scarce commodity. By infecting and killing prokaryotic cells (bacteria, archaea) in ocean sediments, viruses act as efficient organic carbon recycling machines.
Scientists found that in every sediment tested, from active tidal flats, open oceans and nutrient-poor gyres, viruses vastly outnumbered prokaryotic host cells. Active viruses didn’t just exist in the oceanic topsoil, but rather permeated through deep layers laid down millions of years ago. Bacteriophages (viruses that infect bacteria) could be found in layers of sediment 320m deep, and in ancient layers from ~14 million years ago.
These exciting findings mean that viruses are actively replicating in buried ocean sediments all the time, and are thus making a huge contribution to the maintenance and carbon cycling of oceanic microbial communities.
Engelhardt T, Kallmeyer J, Cypionka H, & Engelen B (2014). High virus-to-cell ratios indicate ongoing production of viruses in deep subsurface sediments. The ISME journal PMID: 24430483