Researchers analyzing water extracted from gas wells drilled 650 to 1,640 feet into the Antrim Shale beneath the Great Lakes discovered a thriving subterranean ecosystem. The findings, published in The ISME Journal, identify 689 unique fungi species and ancient Ice Age water dating back 11,000 years.
Deep beneath the surface of the Great Lakes region, a hidden ecosystem thrives hundreds of feet underground. Researchers investigating gas wells drilled into the Antrim Shale recovered water samples that have remained isolated from the surface for millennia. Isotopic dating traced the liquid back to the Ice Age, indicating it was last in contact with the surface 11,000 years ago as glacial ice sheets melted and carried microbes through porous rock layers.
Antrim Shale Drilling Reveals Subterranean Fungi Diversity
The study cataloged 689 unique fungi species, which includes 13 newly described species thriving in an environment previously thought too harsh for complex life. Analysis of a single water drop revealed roughly 250 fungal cells, a concentration comparable to surface ocean water. Scaling those numbers up reveals that an Olympic-sized swimming pool filled with this subterranean water would contain roughly 12 trillion fungal cells.
The presence of these organisms directly challenges long-held scientific assumptions. Researchers previously suspected that any eukaryotic cells detected through environmental DNA traces in deep subsurface environments were simply dormant or transient.
Challenging Assumptions About Subsurface Life
Measurements of carbon dioxide and methane levels within the collected water samples demonstrate that the organisms actively consume the surrounding rock. By feeding directly on organic material trapped within the shale, these microbes prove that subterranean zones sustain active biological communities.
The research team notes that scientists may be meaningfully underestimating the total biomass and diversity of fungi on Earth because global biodiversity estimates have historically ignored the deep subsurface.
Tardigrades and Worms Form an Underground Food Web
Fungi and bacteria are not alone in the subterranean darkness. Investigators documented microscopic segmented worms and notoriously resilient tardigrades, also known as water bears, living hundreds of feet below ground. These hardy invertebrates, famous for surviving extreme conditions including the vacuum of space, participate in a complex underground food web that includes predator-prey dynamics and likely parasitic relationships.
The shale itself serves as the foundational energy source for this isolated food chain. As these organisms break down the ancient rock and convert components into gas, they alter our understanding of how deep carbon repositories operate.
Implications for Global Carbon Sequestration Models
The discovery carries significant consequences for how scientists model carbon cycling. Environmental researchers traditionally assume that carbon trapped deep underground remains sequestered and inert for extended periods. However, the biological activity of rock-eating fungi, bacteria, and invertebrates complicates carbon sequestration calculations by converting trapped carbon into active gases.
Because these underground spaces prove far more biologically active than previously recognized, the study authors emphasize that fungi need to be incorporated into all future models of carbon cycling and subsurface sequestration.
Worth a look
