Giant viruses discovered on Greenland's ice sheet could limit ice melting

When Laura Perini waves a clear bag filled with a disturbing black ink liquid at the camera, one might think there is widespread environmental pollution in Greenland. It is actually a sample of melting ice. Its color is not alarming because it is due to the natural presence of algae, which begin to multiply as soon as spring begins.

On an exploratory trip to these frozen lands, a researcher in the Department of Environmental Sciences at Aarhus University (Denmark) took these samples in order to analyze their composition. This is how she and her colleagues discovered DNA traces of giant viruses!

A previous discovery of giant viruses occurred in the Arctic Ocean, at a “lake” or more precisely, a body of fresh water overlooking salt water. But this is the first time, according to the new study, that it has been spotted on the ice sheet, in snow blackened by algae (MicrobiomeMay 17, 2024).

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Reducing the melting of ice

Either way, these viruses of extraordinary size—up to millionths of a metre, when “classical” viruses are measured in billionths of a metre—infect microscopic algae. However, the proliferation of these “microalgae” darkens the snow-covered surface and thus reduces its ability to reflect solar radiation.

Thus, giant viruses could indirectly help limit ice melting. This is of particular interest to some scientists, in the context of global warming, especially since when ice melts, the surface reflects sunlight less, thus creating a vicious circle.

“We don't know much about these viruses, but I think they could be useful in mitigating ice melt caused by algae blooms.”Estimates by Laura Perini (press release).

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“We don't know yet how specific it is and how effective it is.”“, confirms the researcher. “But by exploring it further, we hope to answer some of these questions.” One thing is already certain: the giant Greenland viruses are alive and well, as viral messenger RNA (mRNA) sequences corresponding to their DNA sequences have been identified.

A complete ecosystem

However, the giant viruses are not alone in their kingdom. Away from this. “An entire ecosystem surrounding algae.”“, defines Laura Perini. “In addition to bacteria, Mushrooms “Nematodes and yeasts, there are protists that eat algae, different types of fungi that parasitize them, and the giant viruses that we found, that infect them.”

So it is these last three groups – protists, fungi and giant viruses – that the team will have to continue to study in the hope of understanding the natural control mechanism exerted on algae.

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Pending learning more about the exact role of giant viruses in the ecosystem, the researcher promises to publish research later this year. “Another scientific study” Who will reveal? “More information about the giant viruses that infect cultured microalgae that thrive on the surface ice of the Greenland Ice Sheet.”

It also remains to be determined whether, like geoengineering advocates who want to tame the sun, we will be able to tame the power of giant viruses. Or even if that were desirable. Should we not then risk endangering the fragile polar balance?