In the bottom of the oceans, viruses reign supreme
By Denis Delbecq • September 1st, 2008 in 10:55 · Category: Actuality
When the carbon cycle in the oceans is recalled, it is the plankton which immediately comes to mind. But jobs published in Nature on August 27th suggest that the role of viruses was amply under estimating. Having studied 232 samples of sediments gathered in big depth, an international team (Italy, France, the United States) concluded that viruses are the main reason of mortality of microorganisms living in the bottom of the oceans, with mortality rates close to 100 % beyond of thousand metres deep.
According to the researchers, they count 4000000000000000000000000000000 not less than (4×1030) virus in the oceans. When bacteria die of natural death, they are used by bigger organisms. But when they succumb to a virus, they blow up and liberate their carbon in the water, what makes it usable to feed other bacteria. A mechanism which speeds up the carbon cycle in the oceans. Viruses are the first reason of production of organic matter with big depth.
Deep life remains widely misread, so much the conditions of studies are difficult in big depth, and however it represents about 10 % biomasses living on our planet. In this inhospitable world for the man, colossal pressures reign (for example, three hundred times atmospheric pressure in 3000 metres), which make the researchers display the considerable equipment to go to search and to take back up samples and to study them without changing the characteristics of their environment. Financed by the European Union as part of plan HERMES (1), jobs concern depths from 165 to 5000 metres.
Beyond of better one knowledge of living conditions under the surface of the oceans, the researchers stress the role of these viruses in the natural sequestration of the carbon in the oceans. Today, the models of climatic predictions do not take into account the intense production of carbon caused by the underwater viruses. To hope better to include the carbon cycle, will have therefore in knowledge more on spectacular battle to devote themselves viruses and bacteria in abysses.
(1) Hermes: English Research acronym on the hot points of ecosystems in the margins of European waters.
Picture: © Denis Delbecq
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