title: DEWFALL AS A WATER SOURCE FREQUENTLY ACTIVATES THE ENDOLITHIC CYANOBACTERIAL COMMUNITIES IN THE GRANITES OF TAYLOR VALLEY, ANTARCTICA(1).
abstract: Endolithic photosynthetic microorganisms like cyanobacteria and algae are well known from savannas and deserts of the world, the high Arctic, and also Antarctic habitats like the Dry Valleys in the Ross Dependency. These endolithic microbial communities are thought to be at the limits of life with reported ages in the order of thousands of years. Here we report on an extensive chasmoendolithic cyanobacterial community inside granite rocks of Mt. Falconer in the lower Taylor Valley, Dry Valleys. On average, the cyanobacterial community was 4.49 ± 0.95 mm below the rock surface, where it formed a blue-green layer. The community was composed mainly of the cyanobacterium Chroococcidiopsis sp., with occasional Cyanothece cf. aeruginosa (Nägeli) Komárek and Nostoc sp. Mean biomass was 168 ± 44 g carbon · m(-2) , and the mean chl a content was 24.3 ± 34.2 mg · m(-2) . In situ chl fluorescence measurements-a relative measure of photosynthetic activity-showed that they were active over long periods each day and also showed activity the next day in the absence of any moisture. Radiocarbon dating gave a relatively young age (175-280 years) for the community. Calculations from microclimate data demonstrated that formation of dew or rime was possible and could frequently activate the cyanobacteria and may explain the younger age of microbial communities at Mt. Falconer compared to older and less active endolithic microorganisms reported earlier from Linnaeus Terrace, a higher altitude region that experiences colder, drier conditions.
authors.affiliation: Department of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyFaculty of Geography, University of Marburg, Deutschhausstraße 10, D-35032 Marburg, GermanyDepartment of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyBiological Sciences, Waikato University, Hamilton, New Zealand Vegetal II, Farmacia Facultad, Universidad Complutense, Madrid, Spain.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Büdel
authors.affiliation: Department of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyFaculty of Geography, University of Marburg, Deutschhausstraße 10, D-35032 Marburg, GermanyDepartment of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyBiological Sciences, Waikato University, Hamilton, New Zealand Vegetal II, Farmacia Facultad, Universidad Complutense, Madrid, Spain.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bendix
authors.affiliation: Department of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyFaculty of Geography, University of Marburg, Deutschhausstraße 10, D-35032 Marburg, GermanyDepartment of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyBiological Sciences, Waikato University, Hamilton, New Zealand Vegetal II, Farmacia Facultad, Universidad Complutense, Madrid, Spain.
authors.forename: Fritz R
authors.initials: FR
authors.lastname: Bicker
authors.affiliation: Department of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyFaculty of Geography, University of Marburg, Deutschhausstraße 10, D-35032 Marburg, GermanyDepartment of Biology, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, GermanyBiological Sciences, Waikato University, Hamilton, New Zealand Vegetal II, Farmacia Facultad, Universidad Complutense, Madrid, Spain.
authors.forename: T G
authors.initials: TG
authors.lastname: Allan Green
keywords: Antarctica; Chroococcidiopsis; Dry Valleys; chl fluorescence; dew activation; endolithic cyanobacteria; microclimate; radiocarbon age; water source