--A photo that the French Consulate took of the Tara, a research vessel dedicated to studying the diversity of oceanic plankton and their viruses, from (http://www.sciencetimes.com/articles/6613/20150523/sampling-the-world-s-oceans-on-a-global-scale-reveals-the-complex-relationship-between-viruses-and-microbes.htm)
In March 2011, the Tara, a 36-meter research ship, started a series of expeditions that would form part of a multi-year journey-- about 180,000 miles of sailing. One of the scientists on board, Melissa Duhaime, spent most of the voyage not looking at open ocean animals, but at the diversity of oceanic plankton and… and viruses?
Duhaime and her colleagues set out on a quest to quantify the diversity of viruses in the oceans. Through thousands of genetic screens of microorganisms in seawater, over 35,000 species of plankton. most of which were previously undescribed. Oceanic viruses have only been studied since the 1980’s, but no study has even been this ambitious. This study was truly vast in its scope, as it sampled the microbiota between the surface and 6,561 feet deep. The study (http://www.sciencemag.org/content/348/6237/1261498) used quantitative double-stranded DNA and protein analysis to screen for pelagic DNA and RNA viruses. The team found 5,476 species of viruses; only 39 of these were previously known to science. Because of plankton’s importance in global carbon cycles (and therefore importance to the regulation of Earth’s climate), understanding the pathogens of plankton is an important part of understanding marine ecosystems.
They also found that viral communities varied based on the physical conditions and organisms that lived in a given region. They concluded that viruses are passively transported on oceanic currents and locally structured by environmental conditions that affect host community structure. Their findings suggested that a “seed-bank” hypothesis (i.e. high local genetic diversity can exist when individual communities diverge from a common and relatively limited global “common” gene pool) could be used to describe the variations in viral communities across the world’s oceans.
The ocean is a huge place, though. There are undoubtedly even more discoveries to be made about the virology of the oceans.