Scientists have made an unexpected discovery on Greenland’s Arctic ice cap.
As the frozen environment awakens in spring after months spent in darkness each year, signs of life begin to return to Greenland’s icy landscape. Several large animals, including the region’s polar bears, arctic terns and musk oxen, begin to move as sunlight warms the frozen earth.
Now scientists have discovered that these aren’t the only huge lifeforms living on Greenland’s ice, although new research reveals how others went undiscovered for so long.
The invisible ‘giants’ of Greenland
Researchers studying Greenland’s frigid ecosystem report the new discovery of giant viruses thriving on the region’s Arctic ice. These viruses can help control local algae blooms and can even reduce the rate at which ice melts.
Greenland lies dormant on the ice during the months and remains in darkness. When spring arrives, algae begin to bloom, creating large dark areas on the ice sheet. This reduces the sunlight it reflects and causes faster melting, a process that could contribute to global warming.
Laura Perini, a postdoctoral researcher from Aarhus University’s Department of Environmental Sciences, says the giant viruses she and her colleagues discovered alongside these Arctic algae may act as a natural control mechanism that helps curb their blooms.
“We don’t know much about the viruses, but I think they could be useful in reducing ice melt caused by algal blooms,” Perini said in a statement. “We don’t know yet how specific they are and how efficient it would be. But by investigating them further, we hope to be able to answer some of those questions.”
At just 20 nanometers in size, viruses are generally much smaller than bacteria. However, the viruses Perini and her colleagues discovered in Greenland are enormous by comparison, growing up to 2.5 micrometers in size, making these “giant” viruses larger than most bacteria.
These invisible giants lurking on Greenland’s ice sheet aren’t the only unusually large viruses scientists know of. In 1981, similar massive viruses were discovered in oceanic environments. Like their icy cousins, these giant viruses also infected green ocean algae. More examples have also been found on land, and even a few variants are known to exist in our bodies.
Still, Perini and her team’s discovery marks the first time that giant viruses have been found that thrive on surface ice and live on snow-dwelling microalgae. These curious organisms were found in dark ice, as well as samples of red snow that the team analyzed.
The new findings challenge past views that the Arctic landscape was barren and devoid of life. Scientists today recognize it as an ecosystem where bacteria, filamentous fungi, yeasts, protists and giant viruses thrive and interact with each other.
“There is a whole ecosystem around the algae. In addition to bacteria, filamentous fungi and yeasts, there are protists that eat the algae, several types of fungi parasitize them, and the giant viruses we found infect them,” says Perini.
Although enormous in size compared to other viruses, these newly discovered Arctic ‘giants’ are still invisible to the naked eye. They might have gone unnoticed had Perini not discovered them while analyzing DNA in the samples her team collected, where sequences similar to other known giant viruses were observed.
By extracting and sequencing mRNA from their samples, Perini and her team confirmed that viruses were present and living on the ice.
Unlike normal viruses, giant viruses can convert their DNA into mRNA on their own, while smaller variants rely on hijacking the cells of their hosts. Many questions remain about these unusually large viruses, including what ecological role they play and about their specific hosts.
Further studies are expected to reveal how these giant viruses interact in their Arctic ecosystem, and in the coming months Perini and her team plan to publish additional research on how these viruses infect microalgae, which could help reveal new insights in the curious. invisible” giants that thrive on the Greenland ice sheet.
Perini and her team’s article, ‘Giant viral signatures on the Greenland ice sheet’, was published in the journal Microbiome in May.
Micah Hanks is editor-in-chief and co-founder of The Debrief. He can be reached by email at micha@thedebrief.org. Follow his work michahanks.com and on X: @MichaHanks.