Gradient Studies Reveal the True Drivers of Extreme Life in the Atacama Desert

authored by
D. Boy, R. Moeller, L. Sauheitl, F. Schaarschmidt, S. Rapp, L. Brink, S. Gschwendtner, R. Godoy Borquez, FranciscoJ Matus, M. A. Horn, G. Guggenberger, J. Boy

Studies of hyper-arid sites contribute to our understanding on how life adapted to extreme conditions. They are often used to further deduce implications for extraterrestrial biology by the so-called analogue site-approach. The Atacama Desert, Chile, is one of the most prominent analogue sites despite its neighboring productive ecosystems due to its hyper-aridity and geochemical features resembling Martian environments. We hypothesize that many drivers of extremophile life in analogue sites are only mistakenly attributed to aridity alone, thus obscuring a clear view of the far more complex process interactions originating in nearby earthly ecosystems. To test this, we investigated 54 soil profiles up to 60 cm of soil depth along of four transects in the Atacama Desert, either running parallel (S-N) or perpendicular (W-E) to the Andes. Our objective was to reveal the processes controlling the formation of soil organic carbon (SOC) as the most reliable proxy for microbial life in order to understand the boundary conditions of life in extreme habitats. Further, we aimed at identifying analogue sites as uncompromised as possible by external influences of for example, vegetated or marine ecosystems. We found a mixture of influences driving habitable conditions on gradients perpendicular to the Andes, for example, fog and precipitation scavenging caused by altitudinal variations and differing proximity to the Pacific Ocean, while transects parallel to the Andes were much less biased by external factors. Our results show that studies on life under extreme conditions should clarify the explanatory strength of the investigated factors by a gradient study approach.

Institute of Microbiology
Institute of Soil Science
Department of Biostatistics
Leibniz Research Centre FZ:GEO
External Organisation(s)
German Aerospace Center (DLR)
Dastani Consulting GmbH
University of Tübingen
Helmholtz Zentrum München - German Research Center for Environmental Health
Universidad Austral de Chile
Universidad de la Frontera
Journal of Geophysical Research: Biogeosciences
Publication date
Publication status
Peer reviewed
Sustainable Development Goals
SDG 14 - Life Below Water
Electronic version(s) (Access: Open)