In the last decades the development of new technological and methodological tools has allowed demonstrating that microbes dominates both in terms of abundance and biomass the world oceans. Microbes are of size ranging from 0.02 to a few micrometres and include a wide diversity of viruses, prokaryotes (Bacteria and Archaea), and eukaryotes (either phototrophic and heterotrophic).
These tiny particles, either suspended in the water column or attached to the sediments play crucially important functions and control the global biogeochemical cycles. More recently it has been also demonstrated that viruses are by far more important than previously thought. In particular we now know that viruses are the most abundant biological entities of the biosphere, with current estimates of the global viral abundance in the order of 1030-1031.
They outnumber prokaryotes by at least one order of magnitude. This huge numerical abundance suggests that viruses can account also for the vast majority of the genetic diversity of the Earth (figure 1). Being not able to self-replicate, viruses invade other organisms and use their cell’s machinery to propagate. They can infect all the known life forms of the oceans, from the largest mammals to the smallest marine microbes. Indeed, also tiny viruses inside larger viruses have been recently discovered. [...]
Documents à télécharger