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Abstract EANA2024-49


Volcanic lakes as extreme habitats for astrobiological exploration: the HELENA project

Nina Kopacz (1), Laura Zucconi (1), Micol Bellucci (2), Claudia Pacelli (2), Alessia Cassaro (1,2), Fabiana Canini (1), Rebecca Martellotti (3), Barbara Cavalazzi (3)
(1) University of Tuscia, Viterbo, Italy, (2) Italian Space Agency, Rome, Italy, (3) University of Bologna, Bologna, Italy


Extreme terrestrial environments, once thought to be devoid of life, have been found to be inhabited by extremophilic microorganisms, expanding our view of the limits of habitability and spurring the exploration of such environments in the context of the search for life on Mars (Schulze-Makuch et al., 2008). Evidence of an active hydrological cycle in Mars’ past has come from the investigation of diagenetic episodes by aqueous alteration at Gale Crater by the Curiosity rover (Fraeman et al., 2020; David et al., 2020; Achilles et al., 2020), along with geomorphological features indicating lakes (Fairén et al., 2003) and shallow sediments (Rapin et al., 2019). Terrestrial volcanic lakes serve as Noachian Mars analogue environments and can help us in assessing and interpreting the potential biological history of Mars and in developing exploration strategies for ESA ExoMars and Mars Sample Return missions. 

The HELENA project aims to characterize the Bagno dell'Acqua Lake on the island of Pantellerìa (Sicily) from an astrobiological perspective. A lake of volcanic and hydrothermal origin located inside a caldera, it is host to polyextreme environments characterized by an arid climate, intense seasonal evaporation, high thermal water temperatures, a variable pH from slightly acidic to strongly alkaline, high salinity as a consequence of evaporation and high concentrations of metals and other chemical elements due to the interaction of water with volcanic products (i.e., rocks, gases, and thermal fluids). We aim to characterize the biodiversity, the geobiofacies, and the biosignatures present within the lake. 

In understanding the microbial biodiversity (prokaryotic and eukaryotic) in the context of this relatively little known polyextremophile, we can identify new endemic extremophiles or polytolerants. Furthermore, the study of biosignatures and mineral/microbe interactions is advantageous in this environment since the terraced structures preserve portions of the paleo-lake, which allows for a comparative study on (sub)fossil counterparts to verify the potential for preserving biosignatures over time. 

Here we describe the sampling campaign, completed in June, 2024, and the ensuing plans for the characterization of the microbial abundance and diversity associated with the depositional environment and the identification and distribution of habitats and paleohabitats and associated geobiofacies through paleoenvironmental reconstructions.

References:

Achilles, C., E. et al. (2020), Journal of Geophysical Research: Planets 125, e2019JE006295.

David, G., A. et al. (2020), Journal of Geophysical Research: Planets 125, e2019JE006314.

Fairén, A. G., et al. (2003), Icarus 165, 53–67.

Fraeman, A. A., et al. (2020), Journal of Geophysical Research: Planets 125, e2020JE006527.

Rapin, William, et al. (2019), Nature Geoscience 12.11: 889-895.

Schulze-Makuch, D., et al. (2008), International Journal of Astrobiology 7, 117–141.