RNA viruses may differentially shape carbon recycling in the ocean

A new study by researchers at Bar-Ilan University has uncovered that certain ocean viruses—specifically RNA viruses—may disrupt how carbon and nutrients are recycled in the ocean, potentially altering the global carbon cycle.

The research, conducted in partnership with Rutgers University, focuses on viruses that infect microscopic algae known as phytoplankton, which are essential to life on Earth. These tiny organisms not only generate much of the planet’s oxygen but also play a critical role in drawing down carbon dioxide out of the atmosphere. When phytoplankton are infected and killed by viruses, they release dissolved organic matter (DOM) into the surrounding seawater that serve as food for marine bacteria that help recycle a substantial amount of carbon and nutrients.

However, the study, recently published in Science Advances, found that not all viral infections lead to the same outcome. Researchers compared the effects of RNA and DNA viruses on a common phytoplankton species and discovered a key difference: DOM from an DNA virus infection supports bacterial growth, while DOM from an RNA virus infection does not. Instead, it makes recycling more difficult— causing bacteria to expend more energy attempting to break down complex proteins.

These shifts may alter how much organic carbon sinks deeper into the ocean, where it can remain stored for longer periods—potentially keeping it out of the atmosphere and influencing global climate patterns.

“Viruses don’t just kill phytoplankton; they fundamentally alter the way carbon moves through the ocean,” said lead author Dr. Chana Kranzler, from the Goodman Faculty of Life Sciences at Bar-Ilan University. “We are learning that distinct types of viral infections can impact surrounding microbial communities in different ways, potentially reshaping how carbon is recycled and the amount of carbon that is ultimately sequestered in the deep ocean.”

Given that every drop of seawater contains millions of viruses, these findings suggest a hidden layer of complexity in how oceans regulate climate. While both RNA and DNA viruses are widespread, their ecological roles are only beginning to be understood.

This study opens new avenues for research into how phytoplankton and viruses shape the ocean’s biogeochemical cycles—and how those processes, in turn, affect Earth’s climate.