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Marine viruses may help slow climate change

Scientists have recently identified 5,500 marine RNA virus species. The study has revealed that several of these species could drive carbon absorbed from the atmosphere to be stored on the ocean floor.

A small portion of these newly identified species had “stolen” genes from organisms they infected, helping researchers identify their hosts and functions in marine processes. This research is leading to a fuller understanding of the role these tiny particles play in the ocean ecosystem.

“The findings are important for model development and predicting what is happening with carbon in the correct direction and at the correct magnitude,” said Ahmed Zayed, a research scientist at The Ohio State University and co-first author of the study.

Lead author Matthew Sullivan envisions identifying viruses that, when engineered on a massive scale, could function as controllable “knobs” affecting how carbon in the ocean is stored.

“As humans put more carbon into the atmosphere, we’re dependent on the massive buffering capacity of the ocean to slow climate change. We’re growing more and more aware that we might need to tune the pump at the scale of the ocean,” said Sullivan.

“We’d be interested in viruses that could tune toward a more digestible carbon, which allows the system to grow, produce bigger and bigger cells, and sink. And if it sinks, we gain another few hundred or a thousand years from the worst effects of climate change.”

These RNA viruses were detected in plankton samples collected by the Tara Oceans Consortium, a global study on the impact of climate change on the ocean. The research project aims to predict how the ocean will respond to climate change by understanding the organisms that absorb half of human-generated carbon in the atmosphere and produce half of the oxygen we breathe.

These marine viral species infect organisms using their cellular machinery to make copies of themselves. While this is bad for the host, the virus could generate environmental benefits, such as reducing a harmful algal bloom.

As a result of the statistical analysis, the study revealed that while warmer regions usually are more biodiverse, the diversity of RNA viral species was higher than expected in the Arctic and Antarctic.

“When it comes to diversity, viruses don’t care about the temperature,” said co-first author Guillermo Dominguez-Huerta. “There were more apparent interactions between viruses and cellular life in polar areas. That tells us the high diversity we’re looking at in polar areas is basically because we have more viral species competing for the same host. We see fewer species of hosts but more viral species infecting the same hosts.”

The viruses were also found to integrate themselves into genomes accidentally. “When it happens, it’s a clue about the host because if you find a virus signal within a host genome, it’s because at some point the virus was inside the cell,” Dominguez-Huerta said.

The experts found that RNA viruses mostly infect fungi and microbial eukaryotes and invertebrates. Only a tiny fraction of the viruses infect bacteria.

Further analysis identified 1,243 RNA virus species connected to carbon export. Eleven species were involved in promoting carbon export to the bottom of the sea. Of those, two viruses linked to hosts in the algae family were selected as the most promising targets for follow-up.

“I’m envisioning our use of AMGs and these viruses that are predicted to infect particular hosts to actually dial up those metabolic maps toward the carbon we need. It’s through that metabolic activity that we probably need to act.” said Sullivan.

Sullivan, Dominguez-Huerta and Zayed are also team members in the EMERGE Biology Integration Institute at Ohio State.

The study is published in the journal Science.

By Katherine Bucko, Staff Writer

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