Modern stromatolite ecosystems at alkaline and hipersalyne high-altitude lakes at the Argentinean Puna.

FARÍAS, MARÍA EUGENIA; POIRE, DANIEL G.; ARROUY, MARÍA JULIA; ALBARRACÍN, VIRGINIA

Stromatolites: interaction of microbes with sediments

Springer

Lugar: Heidelberg; Año: 2011; p. 427 - 440

High-Altitude Lakes at the northwest of Argentina in the Puna and Andean regions (HAAL), are considered extreme environments of biotechnological interest. The HAAL ecosystems are almost unexplored systems of shallow lakes formed during the Tertiary geological period, distributed in the geographical area called the Puna at altitudes from 3,000 to 6,000 m above sea level. Most of these wetlands are completely isolated, experience a wide daily range in temperatures (40 ºC), are slight saline to hypersaline, and are subject to low phosphate availability and to high intensity of solar UV-B radiation. The HAAL ecosystems are unique not only for their geographical characteristics and broad range of extreme environments but also for their abundant biodiversity. The microbial communities that have evolved within these high-altitude aquatic ecosystems tolerate chemical and physical stresses such as wide fluctuations in daily temperatures, hypersalinity, and variable pH and have proved to be adapted to high levels of UV radiation, a low level of nutrient availability, and high concentrations of heavy metals, especially arsenic. The high altitude and low latitude geographical position of the HAAL expose the indigenous extremophilic communities to high solar irradiance (i.e. 165% higher than at sea level) with instantaneous UV-B flux reaching 17 Wm-2; UV-flux is twice the amount of present-day equatorial Mars, while UV-B is half the amount on Mars. Hence, these environments have been proposed for prospection studies on astrobiology. The aim of this work is to make the first description of extreme living stromatolites surviving above 4,000 metters at Laguna Socompa. The environment, morphological description, preliminary biological and mineralogical composition of these new modern stromatolites are presented in this study.