Fresh Icelandic Lava Reveals How Life Takes It’s First Footsteps — On Earth and Beyond

Catastrophic events like major volcanic eruptions can wipe out all life in an area, leaving behind a blank slate. But as nature always finds a way back, researchers are increasingly curious about what that recovery actually looks like, starting at the microscopic level.

Understanding how bacteria first colonize fresh terrain doesn’t just tell us how plants and animals eventually return. It also offers clues about how life may have emerged on Earth in the first place, and how it could arise on other planets shaped by volcanism.

To get at those questions, a team of scientists from the University of Arizona took advantage of a rare natural experiment: a series of eruptions from Iceland’s Fagradalsfjall volcano between 2021 and 2023. The researchers sampled lava flows almost immediately after they cooled, making the study that was published in Nature Communications Biology the first to closely track how microbes move into a brand-new habitat right as it’s being formed.

Studying Lava Offers a Window into Early Life

Volcanic eruptions provide something researchers rarely get in nature: a truly sterile starting point.

“The lava coming out of the ground is over 2,000 degrees Fahrenheit, so obviously it is completely sterile,” said first author Nathan Hadland, a doctoral student in the University of Arizona’s Lunar and Planetary Laboratory in a press release. “It’s a clean slate that essentially provides a natural laboratory to understand how microbes are colonizing it.”

Although previous research has examined how organisms reclaim disturbed environments, most of those studies focus on plants and animals, not microbes. This new work instead looks at primary succession at the microbial level, watching life arrive as the habitat itself is still being formed. Unlike earlier studies that sampled lava months after an eruption, Hadland’s team collected material within hours of solidification.

They collected DNA from freshly formed lava, along with rainwater and airborne aerosols. Using advanced statistical and machine-learning techniques, the team identified which organisms showed up first, how these tiny ecosystems developed, and where the microbes originated.

Read More: Potential Biosignatures on Mars May Reflect Ancient Life in Mineral-Rich Rocks

Fresh Lava Invites Hardy Bacteria

Conditions on new lava flows are extreme. Although Iceland receives plenty of rain, freshly deposited lava holds little water and contains almost no organic nutrients. As a result, these sites are among the lowest-biomass environments on Earth, comparable to Antarctica or Chile’s Atacama Desert.

Despite this, single-celled organisms colonized the lava surprisingly quickly. Microbial diversity increased steadily during the first year after an eruption, then dropped sharply after the first winter.

“It appears that the first colonizers are these ‘badass’ microbes, for lack of a better term,” Hadland said, “the ones that can survive these initial conditions, because there’s not a lot of water and there’s very little nutrients.”

Over the following months and seasonal shifts, the microbial community began to stabilize as additional organisms arrived via rainwater or spread in from nearby areas. One of the study’s most striking findings was the outsized role rain played in shaping these early ecosystems.

“We see most of the microbes are coming from rainwater, and that’s a pretty interesting result,” Hadland said.

Knowing that rainwater is not sterile, as microbes can float freely in the atmosphere or hitch rides on dust particles, the magnitude of the seasonal changes surprised the team.

“Seeing this huge shift after the winter was pretty amazing,” said co-author and associate professor Solange Duhamel in the release, “and the fact that it was so replicable and consistent over the three different eruptions — we were not expecting that.”

What It Means for Life Beyond Earth

“For the first time, we are beginning to gain a mechanistic understanding of how a biological community established over time, from the very beginning,” Duhamel said. Those insights could extend far beyond Iceland.

Looking beyond our own planet, we know that much of Mars’ surface is basaltic and shaped by volcanic processes similar to Earth’s. Although Martian volcanism has largely ceased, past eruptions may have created short-lived windows of habitability.

Grasping how microbes colonize fresh lava on Earth helps scientists predict how life might have emerged on Mars or any other planet and which biosignatures future missions should search for.

Read More: As Glaciers Retreat, Powerful Volcanoes May Erupt More Frequently Across the Planet

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from a study published in Nature Communications Biology: Three eruptions at the Fagradalsfjall Volcano in Iceland show rapid and predictable microbial community establishment