Scientists have made an unexpected discovery on Greenland’s far northern Arctic ice sheet.
As the frozen environment awakens in the spring after the months it spends blanketed 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 stir as sunlight warms the frozen Earth.
Now, scientists have learned that those aren’t the only massive lifeforms that dwell on Greenland’s ice, although new research is revealing how others have remained undiscovered for so long.
Greenland’s Invisible “Giants”
Researchers studying Greenland’s icy ecosystem report the new discovery of gigantic viruses thriving on the region’s Arctic ice. These viruses could help manage local algal blooms and may even reduce the speed at which ice melts.
Lying dormant on the ice during the months, Greenland remains in darkness. As spring arrives, algae begin to bloom, causing large darkened areas on the ice sheet. This reduces the sunlight it reflects and induces faster melting, a process that could contribute to global warming.
Laura Perini, a postdoctoral researcher from the Department of Environmental Science at Aarhus University, says the giant viruses she and her colleagues have discovered living alongside these Arctic algae may be acting as a natural control mechanism that helps to curb their blooms.
“We don’t know a lot about the viruses, but I think they could be useful in alleviating ice melting caused by algal blooms,” Perini said in a statement. “How specific they are and how efficient it would be, we do not know yet. But by exploring them further, we hope to answer some of those questions.”
At as little as 20 nanometers in size, viruses are generally much smaller than bacteria. However, the viruses Perini and her colleagues have discovered in Greenland are massive by comparison, capable of growing to sizes as much as 2.5 micrometers, making these “giant” viruses larger than most bacteria.
These invisible giants lurking on Greenland’s ice sheet aren’t the only unusually large viruses known to scientists. In 1981, similar massive viruses were discovered in oceanic environments. Like their icy cousins, these giant viruses also infected green ocean algae. Additional examples have also been found on land, and even a few varieties are known to dwell in our bodies.
Still, Perini and her team’s discovery marks the first time that giant viruses have been found thriving on surface ice, subsisting off of microalgae dwelling in snow. These curious organisms were found in dark ice, as well as samples of red snow that the team analyzed.
The new findings challenge past notions 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.
“There’s a whole ecosystem surrounding the algae. Besides bacteria, filamentous fungi and yeasts, there are protists eating the algae, different species of fungi parasitizing them, and the giant viruses that we found, infecting them,” Perini says.
Although they are massive in comparison to other viruses, these newly discovered arctic “giants” are still invisible to the naked eye. They might have gone unnoticed if Perini had 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 transcribe their DNA into mRNA themselves, whereas smaller varieties have to rely on hijacking the cells of their hosts. Many questions remain about these unusually large viruses, including what ecological roles 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 months ahead, Perini and her team plan to publish additional research on how these viruses infect microalgae, which could help to reveal new insights into the curious, “invisible” giants that thrive on the Greenland Ice Sheet.
Perini and her team’s paper, “Giant viral signatures on the Greenland ice sheet,” was published in the journal Microbiome in May.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.