title: An Unusual Inverted Saline Microbial Mat Community in an Interdune Sabkha in the Rub' al Khali (the Empty Quarter), United Arab Emirates.
abstract: Salt flats (sabkha) are a recognized habitat for microbial life in desert environments and as analogs of habitats for possible life on Mars. Here we report on the physical setting and microbiology of interdune sabkhas among the large dunes in the Rub' al Khali (the Empty Quarter) in Liwa Oasis, United Arab Emirates. The salt flats, composed of gypsum and halite, are moistened by relatively fresh ground water. The result is a salinity gradient that is inverted compared to most salt flat communities with the hypersaline layer at the top and freshwater layers below. We describe and characterize a rich photosynthetically-based microbial ecosystem that is protected from the arid outside environment by a translucent salt crust. Gases collected from sediments under shallow ponds in the sabkha contain methane in concentrations as high as 3400 ppm. The salt crust could preserve biomarkers and other evidence for life in the salt after it dries out. Chloride-filled depressions have been identified on Mars and although surface flow of water is unlikely on Mars today, ground water is possible. Such a near surface system with modern groundwater flowing under ancient salt deposits could be present on Mars and could be accessed by surface rovers.
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: McKay
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Jon C
authors.initials: JC
authors.lastname: Rask
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.|Bay Area Environmental Research Institute, Petaluma, California, United States of America.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Detweiler
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Brad M
authors.initials: BM
authors.lastname: Bebout
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.|Bay Area Environmental Research Institute, Petaluma, California, United States of America.
authors.forename: R Craig
authors.initials: RC
authors.lastname: Everroad
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.|Bay Area Environmental Research Institute, Petaluma, California, United States of America.
authors.forename: Jackson Z
authors.initials: JZ
authors.lastname: Lee
authors.affiliation: Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, United States of America.
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Chanton
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Marisa H
authors.initials: MH
authors.lastname: Mayer
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Adrian A L
authors.initials: AA
authors.lastname: Caraballo
authors.affiliation: NASA Ames Research Center, Moffett Field, California, United States of America.
authors.forename: Bennett
authors.initials: B
authors.lastname: Kapili
authors.affiliation: Research and Studies Center, Dubai Police Academy, Dubai, United Arab Emirates.
authors.forename: Meshgan
authors.initials: M
authors.lastname: Al-Awar
authors.affiliation: Geography Department, United Arab Emirates University, Al Ain, United Arab Emirates.
authors.forename: Asma
authors.initials: A
authors.lastname: Al-Farraj
mesh_terms: D001105:Archaea / Q000145:classification / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification; D017753:Ecosystem; D064307:Microbiota; D014479:United Arab Emirates; D014871:Water Microbiology