Giant viruses were first discovered in 1981, when researchers found them in the ocean. These viruses had specialized in infecting green algae in the sea. Later, giant viruses were found in soil on land and even in humans. But it’s the first time that giant viruses have been found living on the surface ice and snow dominated by snow algae. In Greenland, these viruses probably regulate the growth of snow algae on the ice by infecting them.
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The giant virus species Pandoravirus salinus. Image credit: IGS CNRS-AMU.
“Every spring when the Sun rises in the Arctic after months of darkness, life returns,” said Aarhus University researcher Laura Perini and her colleagues.
“The polar bears pop up from their winter lairs, the arctic tern soar back from their long journey south and the musk oxen wade north.”
“But the animals are not the only life being reawakened by the spring Sun. Algae lying dormant on the ice starts blooming in spring blackening large areas of the ice.”
“When the ice blackens it’s ability to reflect the Sun diminishes and this accelerates the melting of the ice. Increased melting exacerbates global warming.”
“But we might have found a way to control the snow algae growth — and maybe in the long run reduce some of the ice from melting.”
In their new study, the authors found signatures of giant viruses in snow and ice samples from the Greenland ice sheet.
They suspect that these viruses feed on the snow algae and could work as a natural control mechanism on the algae blooms.
“We don’t know a lot about the viruses, but I think they could be useful as a way of alleviating ice melting caused by algal blooms,” they said.
“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.”
“We analyzed samples from dark ice, red snow and melting holes (cryoconite),” they explained.
“In both the dark ice and red snow we found signatures of active giant viruses.”
“And that is the first time they’ve been found on surface ice and snow containing a high abundance of pigmented microalgae.”
“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.”
“In order to understand the biological controls acting on the algal blooms, we need to study these last three groups.”
“Which hosts the giant viruses infect, we can’t link exactly. Some of them may be infecting protists while others attack the snow algae. We simply can’t be sure yet,” Dr. Perini said.
“We keep studying the giant viruses to learn more about their interactions and what is exactly is their role in the ecosystem.”
The team’s paper was published in the journal Microbiome.
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L. Perini et al. 2024. Giant viral signatures on the Greenland ice sheet. Microbiome 12, 91; doi: 10.1186/s40168-024-01796-y
