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The High Lakes Project
[edit]Overview
[edit]The High Lakes Project (HLP) was a multidisciplinary astrobiological investigation studying high altitude lakes at the summit of high volcanoes in the Central Andes of Bolivia and Chile to collect new knowledge about the biosphere of planet Earth, the evolution of life and its adaptation to climate changes and its extrapolation to primitive Mars conditions.
The project lasted 14 years, starting in 2002 and ending in 2016, with yearly expeditions to the study sites from 2002 to 2008. It involved around 50 scientists from 26 institutions in 9 countries.
It was funded by both public and private organizations, including NASA Astrobiology Institute, National Science Foundation, SETI Institute, Google, universities support, and many others.
Objectives
[edit]Its primary objective was to understand the impact of increased environmental stress on the modification of lake habitability potential during rapid climate change as an analogy to early Mars. Furthermore, the project searched to assess the impact of low-ozone/high solar irradiance in non-polar aquatic environments, the documentation of poorly known ecosystems, and the quantification of the impact of climate change on lake environment and ecosystem.
The scientific team
[edit]Due to its long lasting nature and the yearly expeditions scheduling, the project saw the participation of many scientists and experts in every one of the expeditions trips; including planetary and Earth scientists, engineers, assistants and technicians with knowledge and experience on field research under high altitude environmental conditions.
Some of the collaborating investigators were:
Edmond A. Grin - SETI Institute/NASA Ames Research Center (USA)
Guillermo Chong - Universidad Católica del Norte (Chile)
Edwin Minkley Jr. - Carnegie Mellon University (USA)
Andrew N. Hock - University of California (USA)
Youngseob Yu - Carnegie Mellon University (USA)
Leslie Bebout - NASA Ames Research Center (USA)
Erich Fleming - SETI Institute (USA)
Donat P. Häder - Universität Erlangen-Nürnberg (Germany)
Cecilia Demergasso - Universidad Católica del Norte (Chile)
John Gibson - University of Tasmania (Australia)
Lorena Escudero - Universidad Católica del Norte (Chile)
Cristina Dorador - Universidad de Antofagasta (Chile)
Darlene Lim - NASA Ames Research Center (USA)
Clayton Woosley - SETI Institute/NASA Ames Research Center (USA)
Robert L. Morris - SETI Institute/NASA Ames Research Center (USA)
Cristian Tambley - Commonwealth Handling Equipment Pool (Chile)
Victor Gaete - Universidad Católica del Norte (Chile)
Matthieu E. Galvez - The Paris School of Mines (France)
Eric Smith - Discoverer Ketty Lund Exploration vessel (USA)
Ingrid Uskin-Peate - University of Iowa (USA)
Carlos Salazar - Clinica Mutual de Seguridad (Chile)
G. Dawidowicz - Environmental Systems Research Institute (USA)
J. Majerowicz - Environmental Systems Research Institute (USA)Study sites
[edit]During the 7 years project's duration and the various scientific expeditions, the research teams climbed, explored, and set up field experiments at different high altitude locations (mostly volcanoes), scattered around the border between Bolivia and Chile in the Andes mountain range with elevations ranging from the 13,800 feet (4,200 m) and the 19,698 ft (6,004 m).
These sites were:
| Location | Altitude | Country |
|---|---|---|
| Aguas Calientes Salt Flat | 4,200 m (13,800 ft) | Chile |
| Lejía Lake | 4,325 m (14,190 ft) | Chile |
| Laguna Blanca | 4,350 m (14,270 ft) | Bolivia |
| Laguna Verde | 4,310 m (14,140 ft) | Bolivia |
| Escalante Ponds | 5,700 m (18,700 ft) | Bolivia |
| Pukintika Lake | 5,850 m (19,190 ft) | Bolivia/Chile |
| Simba Volcano | 5,870 m (19,260 ft) | Chile |
| Licancabur Lake | 6,004 m (19,698 ft) | Bolivia/Chile |
Field and laboratory methods
[edit]The research project included mapping the volcanoes' crater geology and topography, surveying the depth, topography and temperature of the lakes bottom, characterization of the lakes organisms and the testing of a two-wheeled Mars mini-rover concept.
Cabrol and several other scientists also free dived to collect biological samples and sediments at various locations in Licancabur Lake that were not accessible by boat. During their dives, they took underwater pictures and video to document the lake's biology and its habitats.
Samples returned from the lakes during the missions were transferred to a support team of scientists at the town of Antofagasta, for preliminary analysis. Most samples, however, were flown to the United States for testing.
Additionally, data-collection stations with instruments and experiments to measure UV and its effect on life in the area were set up. Said stations also measured temperature, water properties and other conditions.
Findings
[edit]Climate
[edit]Many altiplanic lakes were formed and/or reached their peak volume under precipitation regimes of 400–700 mm/yr or more during deglaciation at the end of the last glacial maximum 18,000–14,000 years ago and started to recede at the turn of Holocene.
These results support a more humid climate over the Central Andes during pre-Holocene.
Conditions at each sites were found to be dictated mainly by altitude, the yearly reach of the altiplanic winter, the proximity to the Atacama Desert (40 km on average), and to a lesser extent, winter weather systems from the Pacific Ocean.
The altiplanic winter is the major contributor to atmospheric recharge for the lakes (80% on average). Winter weather systems are a minor component with less than 20%. The impact of the altiplanic winter increases for the sites closer to Argentina.
Physical Environment
[edit]Average cold temperatures, strong solar irradiance, and permanent ozone depletion characterize the environment at all lakes.
The meteorological stations recorded yearly temperature extremes ranging from −40°C to +5°C . Out-of-normal range temperatures were occasionally monitored during field campaigns. Unusually warm or cold temperatures were recorded during the November field campaigns.
Temperature and UV vary along the same gradients but changes are not parallel over space and time. Inverse relationships between UV and temperature are observed during those fluctuations.
Altitude and latitude generate an atmosphere permanently depleted in ozone. Daily fluctuations and recovery patterns are consistent with models of ozone minihole formation generated outside the polar regions as the result of the correlation between local short-term fluctuations of total ozone and tropospheric weather systems.
Chemical Environment
[edit]The lakes are closed basins and (with the exception of Salar de Aguas Calientes) relatively small, thus respond rapidly to atmospheric changes. As a result, the variable input of the altiplanic winter and associated hydrological disequilibrium generates a dynamical chemical habitat.
Life
[edit]Cyanobacterial composition of a variety of microbial mats present in Laguna Blanca, Laguna Verde and Licancabur were characterized.
Based on a sequence identities and cell culture morphologies, these cyanobacterial communities are primarily composed of nitrogen fixing taxa (e.g., Calothrix, Nostoc, Nodularia) as well as a large number of cyanobacteria belonging to the form-genus Leptolyngbya.
At Salar de Aguas Calientes, Lejía, and Simba, the 13 cultures isolated belong to different genus of the Gammaproteobacteria group. The cultures for Aguas Calientes were identified as Serratia sp., Shewanella sp., Aeromonas sp., and Halomonas sp. for Lejía. Exiguobacterium sp. is common to both lakes. The microbial abundance is lower in Lejía than in Aguas Calientes. The Bacteroidetes group is the most frequent in all samples. Bacterial phyla include Proteobacteria (alpha, beta, gamma and delta subgroups), Firmicutes, Actinobacteria, Verrumicrobia and Cyanobacteria. Microbial communities of the acidic Simba lake are similar to those typically found in low PH environments.
Most of the sequences exhibited less than 97% similarity with their closest relatives in GenBank, highlighting the unique and unexplored character of the microbial communities in these environments.
Four of the lakes support zooplankton, the densest populations being at Licancabur, Laguna Blanca, and Salar de Aguas Calientes.
At Licancabur, the population includes at least two calanoid copepod species, two species of ostracod, three species of cladoceran, and a rotifer. The samples contain a significant proportion of previously undescribed species, most of them pigmented, indicating adaptation to high-UV. Licancabur is now the highest known habitat for any species of chironomid (Cricotopus sp.); the previous record was 5600 m in the Himalayas. Not all organisms have yet been identified to species level.
Conclusions
[edit]The long term study's results suggest that in one of the best environmental analogs to early Mars, including a UV flux double that of present-day Mars at the equator and UVB only half that of the red planet, solar irradiance, albeit critical is only one among many variables (e.g., chemistry, salt contents, DOC, water column depth, water supply, temperature) that define habitability potential. The interplay of these variables is unique for each body of water. As a result,habitability potential and survivability depend equally on the lake’s own characteristics and on external factors, such as environment and climate, as it must have been the case on early Mars.
Some of the lakes host complex ecosystems, including zooplankton irrelevant to Mars. Cyanobacteria and bacterial communities are, on the other hand, of potential relevance. Although it can be argued that cyanobacteria never existed on Mars, they are the first terrestrial fossils. Their early Archean age corresponds to the tail end of habitable conditions on Mars. Understanding how they do adapt to the high lakes environmental conditions will provide in the future important clues to assess life potential on early Mars.