New ecosystems in the deep subsurface follow the flow of water driven by geological activity

Abstract

Eukarya have been discovered in the deep subsurface at several locations in South Africa, but how organisms reach the subsurface remains unknown. We studied river-subsurface fissure water systems and identified Eukarya from a river that are genetically identical for 18S rDNA. To further confirm that these are identical species one metazoan species recovered from the overlying river interbred successfully with specimen recovered from an underlying mine at −1.4 km. In situ seismic simulation experiments were carried out and show seismic activity to be a major force increasing the hydraulic conductivity in faults allowing organisms to create ecosystems in the deep subsurface. As seismic activity is a non-selective force we recovered specimen of algae and Insecta that defy any obvious other explanation at a depth of −3.4 km. Our results show there is a steady flow of surface organisms to the deep subsurface where some survive and adapt and others perish. As seismic activity is also present on other planets and moons in our solar system the mechanism elucidated here may be relevant for future search and selection of landing sites in planetary exploration.

Rock Surface Fungi in Deep Continental Biosphere—Exploration of Microbial Community Formation with Subsurface In Situ Biofilm Trap

“…Deep biosphere microbial communities reside either as planktic communities in deep groundwater or sessile communities on surfaces [ 7 , 8 , 9 ]. The formation of biofilms and microcolonies on fracture zone rock surfaces has been demonstrated in various deep subsurface settings, e.g., gold mines and deep subseafloor crust [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Drake et al (2017, 2018) recently revealed fossil fungal cryptoendolithic communities with hyphae-like structures from deep drill core rock surfaces, thus linking fungi to deep subsurface biofilms [ 17 , 18 ].…”

The genome of a subterrestrial nematode reveals adaptations to heat

“…H. mephisto separated from Caenorhabditis at least 22 million years ago 52,64 , and likely over 100 million years ago 65 , though calibrating the nematode molecular clock is difficult because of their poor fossil record 64 . Our data suggest that nematodes access the deep subsurface from surface waters facilitated by seismic activity 66 . This ransition from surface to deep subsurface would be expected to exert strong selective pressures on their genomes, which in nematodes are particularly evolutionarily dynamic 6,7,10–12 .…”

The genome of a subterrestrial nematode reveals an evolutionary strategy for adaptation to heat

“…H. mephisto separated from Caenorhabditis at least 22 million years ago 52,64 , and likely over 100 million years ago 65 , though calibrating the nematode molecular clock is difficult because of their poor fossil record 64 . Our data suggest that nematodes access the deep subsurface from surface waters facilitated by seismic activity 66 . This transition from surface to deep subsurface would be expected to exert strong selective pressures on their genomes, which in nematodes are particularly evolutionarily dynamic 6,7,10-12 .…”