Major viral impact on the functioning of benthic deep-sea ecosystems

• Published in: Nature 2008-08, Vol.454 (7208), p.1084-1087
• Main Authors: Weinbauer, Markus, Noble, Rachel, Dell'Anno, Antonio, Corinaldesi, Cinzia, Magagnini, Mirko, Tamburini, Christian, Danovaro, Roberto
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Aquatic ecosystems; Benthos (Aquatic organisms); Biogeochemical cycles; Biological and medical sciences; Biomass; Biosphere; Carbon - metabolism; Deep sea; Detritus; Ecosystem; Ecosystems; Environmental conditions; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments - virology; Heterotrophic Processes; Humanities and Social Sciences; Hydrostatic Pressure; Infections; Marine; Metabolism; Microbial Viability; Microbiology; Mortality; multidisciplinary; Oceans; Oceans and Seas; Physiological aspects; Plankton; Prokaryotic Cells - cytology; Prokaryotic Cells - metabolism; Prokaryotic Cells - virology; Science; Science (multidisciplinary); Sea water ecosystems; Seawater - virology; Sediments; Synecology; Virology; Virus diseases; Virus Physiological Phenomena; Viruses; Viruses - isolation & purification; Viruses - metabolism; Water depth
• ISSN: 0028-0836; 1476-4687; 1476-4679
• DOI: 10.1038/nature07268

Viruses are the most abundant biological organisms of the world’s oceans. Viral infections are a substantial source of mortality in a range of organisms—including autotrophic and heterotrophic plankton—but their impact on the deep ocean and benthic biosphere is completely unknown. Here we report that viral production in deep-sea benthic ecosystems worldwide is extremely high, and that viral infections are responsible for the abatement of 80% of prokaryotic heterotrophic production. Virus-induced prokaryotic mortality increases with increasing water depth, and beneath a depth of 1,000 m nearly all of the prokaryotic heterotrophic production is transformed into organic detritus. The viral shunt, releasing on a global scale ∼0.37–0.63 gigatonnes of carbon per year, is an essential source of labile organic detritus in the deep-sea ecosystems. This process sustains a high prokaryotic biomass and provides an important contribution to prokaryotic metabolism, allowing the system to cope with the severe organic resource limitation of deep-sea ecosystems. Our results indicate that viruses have an important role in global biogeochemical cycles, in deep-sea metabolism and the overall functioning of the largest ecosystem of our biosphere. Deep viral impact: Virus infections in deep-sea microbes feed the world's largest ecosystem Deep-sea sediments contain large reservoirs of carbon in the form of microbial biomass, and the dynamics of this ecosystem are only now being established. A paper in last week's Nature showed that Archaea predominate over Bacteria in an extensive sediment prokaryote community. This week Danovaro et al . report on the impact of viral infections in this ecosystem. Data from 232 sediment samples show that virus production is very high. Viral infections cause the abatement of over 80% of prokaryotic biomass production — close to 100% at depths below 1,000 metres — thereby releasing huge amounts of dissolved organic carbon into the deep seas. In waters otherwise short of resources this injection of nutrients is particularly significant. Viruses therefore appear to play a major role in global biogeochemical cycles, deep-sea metabolism and overall functioning of the largest ecosystem of our biosphere.