![\"Life](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/12\/Life-on-lava.png\")
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\n Wearing protective gear against toxic gases, Solange Duhamel stands next to a lava flow during an outing to collect samples of freshly deposited lava rock. Credit Christopher Hamilton <\/p>\n
Life has a way of bouncing back, even after catastrophic events like forest fires or volcanic eruptions. While nature\u2019s resilience to natural disasters has long been recognized, not much is known about how organisms colonize brand-new habitats for the first time. A new study led by a team of ecologists and planetary scientists from the University of Arizona provides glimpses into a poorly understood process.<\/p>\n
The team conducted field research in Iceland following a series of eruptions of the Fagradalsfjall volcano, located on the southwestern tip of the island. The volcano erupted for a total of three times over the course of the study period, from 2021 until 2023. With each eruption, lava flows blanketed the tundra around the volcano, in some places even covering lava deposits from the previous year.<\/p>\n
\u201cThe lava coming out of the ground is over 2,000 degrees Fahrenheit, so obviously it is completely sterile,\u201d said Nathan Hadland, a doctoral student in the U of A Lunar and Planetary Laboratory and first author of a paper published in Nature Communications Biology. \u201cIt\u2019s a clean slate that essentially provides a natural laboratory to understand how microbes are colonizing it.\u201d<\/p>\n
To untangle the ecological dynamics involved in that process, Hadland and his team searched for clues about where the microbes that colonize fresh lava come from. They collected samples from a variety of different potential sources, including lava that had solidified mere hours before, rainwater, and aerosols \u2013 particles floating in the air. For context, they sampled soil and rocks from surrounding areas.<\/p>\n
The researchers then extracted DNA from these samples and used sophisticated statistical and machine learning techniques to identify the organisms present on freshly imposed lava flows, the composition of these micro-habitats and where they originated.<\/p>\n
While Iceland receives a considerable amount of precipitation, freshly deposited lava rocks don\u2019t hold much water and contain little to no organic nutrients, Hadland explained. To thrive in that scarce environment, organisms have to deal with very low amounts of water and nutrients.<\/p>\n
\u201cThese lava flows are among the lowest biomass environments on Earth,\u201d said co-author Solange Duhamel, associate professor at the U of A\u2019s Department of Molecular and Cellular Biology, in the College of Science, as well as LPL. \u201cThey are comparable to Antarctica or the Atacama Desert in Chile, which is not that surprising considering they start out as a blank slate. But our samples revealed that single-celled organisms are colonizing them pretty quickly.\u201d<\/p>\n
As microbes colonized the new habitat, biodiversity increased over the course of the first year following an eruption. But after the first winter, diversity \u201ctanked,\u201d according to Hadland, probably because the seasonal shifts in environmental conditions were selecting for a specific subset that could survive those conditions. With each subsequent winter, the analyses revealed less turnover and showed that diversity stabilized over time. With all these data, a picture began to emerge.<\/p>\n
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Variation in prokaryote phyla relative abundance as a function of lava rock age and separated by eruption. Less abundant phyla were concatenated under \u201cOthers\u201d but can be found in detail in the Supplementary Data 2.<\/strong><\/p>\n \u2018Badass microbes\u2019 move in first<\/strong><\/p>\n \u201cIt appears that the first colonizers are these \u2018badass\u2019 microbes, for lack of a better term, the ones that can survive these initial conditions,\u201d Hadland said, \u201cbecause there\u2019s not a lot of water and there\u2019s very little nutrients. Even when it rains, these rocks dry out really fast.\u201d<\/p>\n Over the next several months and seasonal shifts, the study revealed, the microbial community begins to stabilize, as more microbes are added with rainwater and \u201cmoved in\u201d from adjacent areas.<\/p>\n A major finding of the study pointed to rainwater playing a critical role in shaping microbial communities on freshly deposited lava, according to the researchers.<\/p>\n \u201cEarly on, it appears colonizers are mostly coming from soil that is blown onto the lava surface, as well as aerosols being deposited,\u201d Hadland said. \u201cBut later, after that winter shift in diversity we observed, we see most of the microbes are coming from rainwater, and that\u2019s a pretty interesting result.\u201d<\/p>\n Scientists have long known that rainwater is not sterile; microbes in the atmosphere, either free floating or attached to dust particles, can even function as cloud condensation nuclei, which are microscopic particles that offer water vapor a surface to latch on to and grow into tiny droplets. In other words, tiny, invisible creatures may play outsized roles in weather and climate phenomena.<\/p>\n \u201cSeeing this huge shift after the winter was pretty amazing,\u201d Duhamel said, \u201cand the fact that it was so replicable and consistent over the three different eruptions \u2013 we were not expecting that.\u201d<\/p>\n While previous studies have looked at how organisms colonize habitat, most of them focus on secondary ecological succession \u2013 the technical term for organisms reclaiming disturbed habitat \u2013 and macro ecology, in other words, plants and animals. But the research in this paper is the first in-depth look at primary succession by microbes \u2013 organisms moving into new habitat as it is being formed, according to the authors. And unlike previous research based on samples collected months after a volcanic eruption, Hadland\u2019s team sampled lava flows as soon as they cooled. Finally, because the eruptions were going on over three years, the team was able to piece together an ecological picture with unprecedented resolution.<\/p>\n \u201cThe fact that we were able to do this three times \u2013 following each eruption in the same area \u2013 is what sets our project apart,\u201d Hadland said. \u201cIn science, we want to measure things three times \u2013 what we call a \u2018triplicate,\u2019 if possible, and that is very rare in a natural environment. For this study, nature essentially is giving us a triplicate.\u201d<\/p>\n From Arizona to Iceland to Mars<\/strong><\/p>\n \u201cFor the first time, we are beginning to gain a mechanistic understanding of how a biological community established over time, from the very beginning,\u201d Duhamel said, adding that one of the study\u2019s implications is to potentially inform the habitability on other worlds such as Mars.<\/p>\n Most of the Martian surface is basaltic and has been modified by volcanic processes just like Earth, Duhamel explained, even though volcanism has quieted down considerably on Mars.<\/p>\n \u201cVolcanic activity injects a lot of heat into the system, and it releases volatile gases, it can melt frozen water beneath the surface,\u201d Duhamel said. \u201cWe can observe these widespread, large volcanic terrains on Mars with remote sensing, and so the idea is that past volcanic eruptions could have created transient periods of habitability.\u201d<\/p>\n How microbes could potentially colonize new environments and unraveling their spatial distribution patterns is a first step toward probing the potential of life on other planets. Earlier this year, Duhamel was part of a team of U of A researchers selected for the inaugural \u201cBig Idea Challenge\u201d award, administered by the Office of Research and Partnerships. Finalist teams will receive $250,000 over two years and strategic guidance to support transformative research that seeks novel solutions to grand challenges.<\/p>\n \u201cWe can begin to tackle questions like, \u2018How does volcanism influence habitability?\u2019 \u2018How do microbes take advantage of those types of environments?\u2019 and apply the answers to similar types of systems that we have observed on Mars.\u201d Duhamel said. \u201cUnderstanding how life could establish itself on a new lava flow on the surface of Mars, or at least how it could have done so in the past and knowing what kinds of biosignature we should look for and could potentially retrieve is a crucial step in that direction.\u201d<\/p>\n Co-authors on the paper include Christopher Hamilton, U of A associate professor in the Department of Planetary Sciences, and Sn\u00e6d\u00eds Bj\u00f6rnsd\u00f3ttir with the University of Iceland in Reykjavik.<\/p>\n