What is it about?
Microbial communities in deep crustal environments are difficult to investigate because these habitats are hard to access. In this study, we explore the depths of the Swiss Alps through the geothermal system of Lavey-les-Bains. This system shows clear seasonal changes in water chemistry reaching down to 500 meters. Interestingly, despite this seasonal mixing, the microbial communities remain consistent over time and show distinct patterns depending on depth. This suggests that deep microbial life is more stable than expected — even when the surrounding environment changes.
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Photo by Martin Adams on Unsplash
Why is it important?
Understanding how life survives deep underground helps us learn more about Earth’s hidden ecosystems. Our findings show that even when surface water mixes with deep groundwater, the microbes living at depth remain unchanged. This challenges the idea that all subsurface life is influenced by surface conditions and highlights how deep environments can stay stable despite seasonal changes above.
Perspectives
Writing this article was a chance to dive deep—literally and scientifically—into a hidden world, which in this case was never investigated in such detail. What fascinated me most was seeing how stable life can be, even under hundreds of meters of rock, while everything above changes with the seasons. I hope this work sparks more interest in the unseen microbial ecosystems beneath our feet.
Sébastien Giroud
Eawag
Read the Original
This page is a summary of: Resilience of deep aquifer microbial communities to seasonal hydrological fluctuations, Proceedings of the National Academy of Sciences, June 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2422608122.
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