Mars Analog: High Lakes

Effect of High UV on Life in High-Altitude Lakes: Analogs to Mars

by Nathalie Cabrol, Edmond Grin,  High Lakes Expedition Team .

high lake at the top of volcano

An expedition to high-altitude lakes in the Bolivian and Chilean Andes was conducted to study the effects of extremes such as high UV on microbial organisms. These lakes are possible analogs to ancient Martian lakes. A large ecosystem of red and white copepods (figure) was discovered at the center of the Licancabur summit lake. These organisms seem to use water as their main shield against UV. A fossil stromatolite community was also studied to provide information on climate change over the past 18,000 years.

Nathalie under water
Natalie under water

Project Progress: Despite harsh weather conditions in the altiplano this year, both planned ascents were completed successfully, one on the Licancabur volcano to continue our work from previous years, and the other one on our new site (Poquentica), another volcano hosting a lake located 800 km north of Licancabur. During our one-month, 800 km, trek through the Bolivian altiplano, the team also sampled about a half-a-dozen new sites (evaporating lakes, salars, and geothermal centers) Achievements include: (1) a new stratigraphical transect in the geological record of Laguna Verde to study the evolution of paleohabitats and life during fast changing climate conditions; (2) Biological sampling and water chemistry of the summit and lower lakes; (3) Retrieval of data from the meteorological station at the summit of Licancabur which logged for one year.. (3) Geophysics: Measurements of UVA, UVB, PAR and UVC were performed; (4) Sampling of frozen soil (or permafrost) on the shore of the Licancabur and Poquentica lakes and sampling of ice from those lakes which were both frozen to depth this year preventing diving. Bin Chen has analyzed salt samples from the 2005. She has identified organic composition in the Laguna Blanca samples. She is using the database to characterize the concentration and structure stability of biogenic carbonaceous contents, especially biomarkers such as hopane and the derivatives, which likely existed in the prokaryotic and eukaryotic membranes; study the chemical structures of the organic species and their interactions with the host environment (as in rock, salt and soil mixtures) to understand the preservation and evolution of the life in local conditions that include extremes of UV radiation, desiccation, cold temperature and salinity. She investigates abiogenic organics and components such as carbonate, oxyanionic mineral groups, sulfides and hydroxides produced from the biological activities. The next step will be to study the chemical stability and relative abundance of the biomakers in the samples obtained from the geological transects in conjunction with the geochemistry, temperatures, pH (current lakes), salinity, UV radiation level, elevation in the transect and paleoenvironment. The correlation will help us understand how both extant and extinct life adapt to changes. (2006 NAI Annual Report)

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