Project Info: Phase 3

Microbial life in the Atacama Desert is ubiquitous and very well-adapted to severe water limitation. Although abundances may vary, all sampling sites investigated to date contain traces of microbial life. Due to the harsh environmental conditions, surfaces are only partially colonized by microbial life (lithobiontic), but microorganisms are particularly active within surface crusts or even below (endolithic). Microbial communities consisting of photoautotrophic and chemoheterotrophic organisms from different groups of bacteria, archaea, and eukaryotes inhabit such endolithic environments. Organic network structures formed by various organisms may significantly modify the surface properties of evaporitic soil crusts, resulting in a protective surface layer similar to a vegetation cover in more humid environments. Wind erosion is widespread in drylands and is the predominant cause of land degradation (Oldeman, 1992; Sterk et al., 2001). Investigations show that areas with well-developed organic networks are less prone to erosion compared to areas where these networks are less developed or lost due to changing environmental boundary conditions, despite microorganisms being present. Although fog is a likely water source for surface and subsurface inhabiting communities in desert environments, the distribution and abundance of microbial networks cannot be correlated solely with the availability of fog moisture. Hence, a detailed characterization of both the surface sediment crust and the organic matter (OM) present within is necessary to shed light on the recent and ancient microbial activity and to estimate surface protection capabilities in relation to and interrelation with the surrounding mineral matrices. These microbial processes play a crucial role in the critical zone of the Atacama Desert and have probably a significant impact on the long-term shaping of its landscapes.