MODERN MICROBIAL LIFE IN SALINE LAKES AND PANS IN AUSTRALIA: A FIELD PERSPECTIVE

Field observations in acid, neutral, and moderately alkaline saline lake and groundwater systems in Australia suggest abundant and sometimes diverse microbial life. We studied 26 shallow saline lakes in southern Western Australia and northwestern Victoria. Our field work included evaluating the sedimentology, water geochemistry, palynology, and microbial activity within these unique and diverse systems. These lakes are ephemeral, having various pHs, and precipitate halite and/or gypsum in siliciclastic-hosted sediments. Features suggestive of microbial life are: (1) gas production from the subsurface, (2) filamentous structures along shores, (3) subaerial and subaqueous mat structures, (4) hydrogen sulfide odors in sediments, (5) juxtaposed sediment colors suggesting reducing and oxidizing conditions in close contact, and (6) multi-hued halite beds. However, the best potential for microbial survival in saline lake/pan deposits may be as entrapped microbial remains in fluid inclusions in halite. Understanding the microbes in saline systems, especially the acid lakes of Western Australia, may have implications for the search for life on Mars.