Jun 14, 2022 - Science

Scientists discover RNA viruses may shape ocean carbon capture

Phytoplankton
Phytoplankton. Along with other types of plankton they can be infected by marine RNA viruses. Photo: Maéva Bardy/Tara Ocean Foundation

RNA viruses that infect plankton may be shaping the ocean's crucial role in carbon cycling, according to a new study.

The big picture: DNA viruses are known to play a role in the ocean's ecosystem but less is known about the diversity of marine RNA viruses, the types of hosts they infect and whether they impact the flow of energy and carbon in oceans.

  • "RNA viruses definitely influence the global ocean ecosystem," says Guillermo Dominguez-Huerta, a virologist at Ohio State University and a co-author of the new study.

Details: The research builds on the team's earlier discovery of more than 5,500 new RNA viruses in the ocean.

  • That work was based on an analysis of more than 35,000 samples collected by the Tara Oceans Consortium at 121 sites around the world.
  • Dominguez-Huerta and virologist Ahmed Zayed, also from Ohio State University, and their colleagues determined whether there were viruses in plankton in the samples by searching for a specific gene, RdRp, that is found across RNA viruses.

In the new study, the team looked at where the RNA viruses are found in Earth's oceans and what hosts they infect.

  • They found the viruses in four different ecological zones: the Arctic; Antarctic; Temperate and Tropical Epipelagic (near the surface of the ocean); and Temperate and Tropical Mesopelagic farther underwater. (DNA viruses occupy five different zones.)
  • They also found marine RNA viruses largely infect fungi and other types of plankton called protists, whereas DNA viruses typically infect bacteria, they report today in the journal Science.

The intrigue: Some of the viruses infect plankton that play a key role in pumping carbon in the ocean. Dead plankton that contain carbon settle to the bottom of the ocean where it is stored for millions of years.

  • And some of the RNA viruses contain genetic material from their hosts. In the hosts, the genes were involved with the cell's metabolism, suggesting the viruses may manipulate the host cell's metabolic pathways to "maximize virus production," they write.
  • It could be another way the viruses influence the ocean's carbon pumping.
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