Virus is not always synonymous with “harmful cause,” carrying negative effects. At least in the deep sea, where plankton viral infections are the engine of the food chain. The news is more than reliable, coming from Spanish-Italian research involving Ismar-Cnr, and published in “Science Advances,” which shows that in the deep oceans, plankton viral infections release 140 gigatonnes of fresh organic carbon each year for the ecosystem food chain. The results? They will help improve estimates of the earth’s global carbon cycle, useful for understanding climate change.
The study
If the depths of the oceans continue to be populated by fish and other sea creatures, the study says, credit is also due to viruses that, by infecting plankton, put essential nutrients back into the ecosystem’s food chain. “The research is based on the analysis of more than a thousand water samples collected, from the surface to depths of 4,000 meters, along the Atlantic, Pacific and Indian oceans during a scientific expedition conducted in 2010 and funded by the Csic called Malaspina Expedition and tracing the eponymous globe circumnavigation expedition led by Alessandro Malaspina in the late 1700s,” explains Gian Marco Luna, an Ismar-Cnr researcher from Ancona and co-author of the study. “We have shown that viruses from deep environments, about which little has been known until now, are able to prey on microbial plankton much more actively than previously thought.”
Specifically, it is estimated that in the global ocean these viruses infect hundreds of trillions of plankton microorganisms every second (one trillion equals trillion). The viruses destroy the infected cells, which thus put their valuable contents, composed of biomolecules of high nutritional quality, back into the surrounding water. Thus, an important fraction of such organic matter becomes nutrients for other microorganisms, according to the effect known as“viral priming,” feeding the entire food web down to the fish.
Effects
Researchers have also shown that viral infection, particularly in the deep ocean, is responsible for the regeneration of a huge amount of dissolved organic carbon. “Using flow cytometry, a laser technique used in biology that allows the detection and counting of cells and viruses in ocean water samples, we showed that viral infection is responsible for the annual release of 140 gigatonnes of carbon (one gigatonnes corresponds to one billion tons), thus contributing to the global ocean carbon cycle,” continues first author of the paper Elena Lara, a Spanish researcher currently with Ismar-Cnr in Venice and associated with Icm-Csic in Barcelona. Viruses, by breaking down the cells of living microbes, then produce fresh organic carbon, made of biomolecules that are more digestible and potentially more usable along the trophic network than the large slice of dissolved organic carbon.
