Ecological successions throughout the desiccation of Tirez lagoon (Spain) as an astrobiological time-analog for wet-to-dry transitions on Mars

Abstract

Tirez was a small and seasonal endorheic athalassohaline lagoon that was located in central Spain. In recent years, the lagoon has totally dried out, offering for the first time the opportunity to analyze its desiccation process as a “time-analog” to similar events occurred in paleolakes with varying salinity during the wet-to-dry transition on early Mars. On the martian cratered highlands, an early period of water ponding within enclosed basins evolved to a complete desiccation of the lakes, leading to deposition of evaporitic sequences during the Noachian and into the Late Hesperian. As Tirez also underwent a process of desiccation, here we describe (i) the microbial ecology of Tirez when the lagoon was still active 20 years ago, with prokaryotes adapted to extreme saline conditions; (ii) the composition of the microbial community in the dried lake sediments today, in many case groups that thrive in sediments of extreme environments; and (iii) the molecular and isotopic analysis of the lipid biomarkers that can be recovered from the sediments today. We discuss the implications of these results to better understanding the ecology of possible Martian microbial communities during the wet-to-dry transition at the end of the Hesperian, and how they may inform about research strategies to search for possible biomarkers in Mars after all the water was lost.

The use of RNA-seq for the study of physiological adaptations of halophiles in extreme environments for astrobiological data interpretation

“…If potential Martian microbial life independently started outside of Earth, what environmental and geochemical stresses existed that a proposed microbial community on Mars had to adapt to in order to thrive? Fairén et al (2023) studied successions of ecological communities in a planetary analog site in Spain following desiccation. They conclude this data could be used interpret and predict hypothetical Martian microbial community at the end of Hesperian (wet-to-dry transition, Figure 2).…”

Editorial: Mars analogs: Environment, habitability and biodiversity

“…These Mars analogs are studied to infer possible processes operating on the Red Planet and their impact on habitability and the search for life. The Mars analogs on Earth span a variety of environments including the super-arid sedimentary plains (e.g., the Qaidam Basin in the north of the Tibetan Plateau, the Mojave Basin in the United States, and the Atacama Desert in South America; Azua-Bustos et al; Peters et al, 2008;Sherwood Lollar et al, 2007;Xiao et al, 2017), the subsurface fracture waters in Precambrian cratons (e.g., the Canadian Shield, the Fennoscandian Shield, and the Kaapvaal Craton; Hays et al, 2017;Onstott, 2016;Preston and Dartnell, 2014), high salinity localities (e.g., Laguna de Tírez, salt mines, and deep-sea brines; Antunes et al, 2011;Antunes et al, 2020;Cockell et al, 2019;Fairén et al, 2023) as well as extremely cold and highly radiative environments (e.g., polar regions, thin atmosphere; DasSarma et al, 2020;Deming and Huston, 2000). These analog settings on Earth are more accessible and offer opportunities 10.3389/fspas.2023.1208367 to collect high-quality mineralogical, geochemical, geochronological, and microbiological data through state-of-theart technologies and instruments.…”