Abstract
Reputed to be the driest desert in the world, the Atacama Desert in the Central Andes of Northern Chile is an extreme environment with high UV radiation, wide temperature variation, and minimum precipitation. Scarce lagoons associated with salt flats (salars) in this desert are the surface expression of shallow groundwater; these ponds serve as refugia for life and often host microbial communities associated with evaporitic mineral deposition. Results based on multidisciplinary field campaigns and associated laboratory examination of samples collected from the Puquios of the Salar de Llamara in the Atacama Desert during austral summer provide unprecedented detail regarding the spatial heterogeneity of physical, chemical, and biological characteristics of these salar environments. Four main lagoons (‘Puquios’) and more than 400 smaller ponds occur within an area less than 5 km2, and are characterized by high variability in electrical conductivity, benthic and planktonic biota, microbiota, lagoon bottom type, and style of mineral deposition. Results suggest that electrical conductivity is a driving force of system heterogeneity. Such spatial heterogeneity within the Puquios is likely to be expanded with temporal observations incorporating expected seasonal changes in electrical conductivity. The complexity of these Andean ecosystems may be key to their ability to persist in extreme environments at the edge of habitability.
Highlights
Reputed to be the driest desert in the world, the Atacama Desert in the Central Andes of Northern Chile is an extreme environment with high UV radiation, wide temperature variation, and minimum precipitation
More than 1285 in situ measurements of electrical conductivity (EC, Fig. 2, Supplemental Table S1) were collected from both the surface brines and depths of the lagoons in the Puquios to characterize environmental gradients; EC is interpreted to be a proxy for the salinity of the lagoon water
The lowest EC value was observed in the surface brine of a peripheral lagoon of Puquio 3 (6.2 mS/cm, Fig. 2b,g), and the highest EC values were observed in the surface brine of the main lagoon of Puquio 4 (164.9 mS/cm, Fig. 2a,g)
Summary
Reputed to be the driest desert in the world, the Atacama Desert in the Central Andes of Northern Chile is an extreme environment with high UV radiation, wide temperature variation, and minimum precipitation. Results based on multidisciplinary field campaigns and associated laboratory examination of samples collected from the Puquios of the Salar de Llamara in the Atacama Desert during austral summer provide unprecedented detail regarding the spatial heterogeneity of physical, chemical, and biological characteristics of these salar environments. Such spatial heterogeneity within the Puquios is likely to be expanded with temporal observations incorporating expected seasonal changes in electrical conductivity The complexity of these Andean ecosystems may be key to their ability to persist in extreme environments at the edge of habitability. Known environmental pressures in the Salar de Llamara include high UV irradiation, extreme aridity, and significant fluctuations of temperature and salinity[38,39], all of which contribute to the characterization of the Puquios as a dynamic extreme e nvironment[40] The high degree of spatial heterogeneity in all measured parameters highlights the need for multi-disciplinary studies across space and time to understand ecosystem function and mineral deposition in extreme environments
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