Viruses found in carbon-storing wetlands play an active role in shaping ecosystem health

The viruses could also help determine if a wetland has been damaged or if restoration efforts are working.

Viruses in wetland soil play a more important role than previously understood and could even be indicators of ecosystem health, according to a new study by researchers from the University of Wisconsin-Madison. Recently published in Nature Microbiology, the study examined viruses in peatlands, which are wetlands that act as vital carbon sinks around the globe.

"We know bacterial processes produce carbon dioxide and methane from this carbon-heavy, peatland soil. But the question is, how do they actually do it, and are there any other components that we have missed out on?" says Kartik Anantharaman, a professor of bacteriology at UW-Madison. "That's where viruses come in."

Peatlands, like other kinds of wetlands, are important land types for storing carbon that would otherwise remain in the atmosphere and contribute to global warming. Now though in a warming world, wetlands are increasingly being damaged, and some are even in danger of contributing carbon to the atmosphere.

With their coauthors from University of Aberdeen and University of Edinburgh, the team analyzed samples taken from seven peatlands across the UK. The peatlands were categorized as either natural, damaged, or restored. Analysis revealed patterns across the viruses present in peatlands that were natural, ones that were damaged, and ones that are restored.

"Viruses are like a keystone predator in the microbial world," says lead author James Kosmopoulos, a PhD student in Anantharaman's lab. "Without them, everything in an ecosystem would be out of whack."

In a natural, pristine peatland, viruses are able to infect cells of microbes, replicate and then kill the cell before leaving to infect other cells. That keeps microbe populations in check and the ecosystem relatively stable. This paper shows that viruses can shift their behavior based on the stability of their ecosystem.

In damaged peatlands, they found that viruses opt to hunker down in infected cells after replicating rather than immediately killing them. The change in viral behavior shifts the dynamics of the soil's microbiome, influencing which bacterium are present and how efficiently bacteria can process and store carbon.

By looking at which viruses are present in a soil sample, researchers could determine if a wetland is natural, has been damaged, or if restoration efforts are working. The research team believes the patterns they have observed across UK peatlands could also be applicable on a global scale.

"Since microbes including viruses play a key role in regulating greenhouse gas fluxes, our results suggest that viruses can act as signals of peatland recovery by providing a window into what's happening below-ground," says Ashish Malik, a coauthor on the paper from the School of GeoSciences, at University of Edinburgh.

In Wisconsin, where 25% of the state is peatland, Kosmopoulos is building a set of long-term data that he hopes can eventually be used to predict wetland health across the state. As this research continues, they hope to investigate how viruses could be useful tools to influence the restoration of peatlands.

This research was supported by funding from the National Science Foundation (DBI204759), National Science Foundation Graduate Research Fellowship Program (2137424) and Human Frontier Science Program (RGP018/2024) . Funding was also provided by UKRI Natural Environment Research Council (NERC), Scottish Universities Partnership for Environmental Research, Doctoral Training Partnership and the NERC Environmental Omics Facility .