Scholarly Work - Land Resources & Environmental Sciences
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8680
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Item Geomicrobiology of Blood Falls: An iron-rich saline discharge at terminus of the Taylor Glacier, Antarctica(2004-09) Mikucki, Jill A.; Foreman, Christine M.; Sattler, Birgit; Lyons, W. Berry; Priscu, John C.Blood Falls, a saline subglacial discharge from the Taylor Glacier, Antarctica provides an example of the diverse physical and chemical niches available for life in the polar desert of the McMurdo Dry Valleys. Geochemical analysis of Blood Falls outflow resembles concentrated seawater remnant from the Pliocene intrusion of marine waters combined with products of weathering. The result is an iron-rich, salty seep at the terminus of Taylor Glacier, which is subject to episodic releases into permanently ice-covered Lake Bonney. Blood Falls influences the geochemistry of Lake Bonney, and provides organic carbon and viable microbes to the lakesystem. Here we present the first data on the geobiology of Blood Falls and relate it to the evolutionary history of this unique environment. The novel geological evolution of this subglacial environment makes Blood Falls an important site for the study of metabolic strategies in subglacial environments and the impact of subglacial efflux on associated lake ecosystems.Item Glacial ice cores: A model system for developing extraterrestrial decontamination protocols(2005-04) Christner, Brent C.; Mikucki, Jill A.; Foreman, Christine M.; Denson, Jackie; Priscu, John C.Evidence gathered from spacecraft orbiting Mars has shown that water ice exists at both poles and may form a large subsurface reservoir at lower latitudes. The recent exploration of the martian surface by unmanned landers and surface rovers, and the planned missions to eventually return samples to Earth have raised concerns regarding both forward and back contamination. Methods to search for life in these icy environments and adequate protocols to prevent contamination can be tested with earthly analogues. Studies of ice cores on Earth have established past climate changes and geological events, both globally and regionally, but only recently have these results been correlated with the biological materials (i.e., plant fragments, seeds, pollen grains, fungal spores, and microorganisms) that are entrapped and preserved within the ice. The inclusion of biology into ice coring research brings with it a whole new approach towards decontamination. Our investigations on ice from the Vostok core (Antarctica) have shown that the outer portion of the cores have up to 3 and 2 orders of magnitude higher bacterial density and dissolved organic carbon (DOC) than the inner portion of the cores, respectively, as a result of drilling and handling. The extreme gradients that exist between the outer and inner portion of these samples make contamination a very relevant aspect of geomicrobiological investigations with ice cores, particularly when the actual numbers of ambient bacterial cells are low. To address this issue and the inherent concern it raises for the integrity of future investigations with ice core materials from terrestrial and extraterrestrial environments, we employed a procedure to monitor the decontamination process in which ice core surfaces are painted with a solution containing a tracer microorganism, plasmid DNA, and fluorescent dye before sampling. Using this approach, a simple and direct method is proposed to verify the authenticity of geomicrobiological results obtained from ice core materials. Our protocol has important implications for the design of life detection experiments on Mars and the decontamination of samples that will eventually be returned to Earth.Item Metabolic activity and diversity of cyoconites in the Taylor Valley, Antarctica(2007-12) Foreman, Christine M.; Sattler, Birgit; Mikucki, Jill A.; Porazinska, D. L.; Priscu, John C.Metabolic activity and biogeochemical diversity within cryoconites from the Canada,Commonwealth, Howard, and Hughes glaciers in the McMurdo Dry Valleys revealed the presence of a productive microbial refuge in this polar desert ecosystem. Fluorescent in situ hybridization showed a high percentage of Cytophaga-Flavobacteria cells in cryoconite sediments (87.2%), while β-Proteobacterial cells dominated the ice overlying the sediment layer (54.2%). The biomass of bacterial cells in the sediments was also greater (4.82 µgC ml-1) than that in the overlying ice (0.18 mgC ml-1) and was related to bacterial productivity (on the basis of thymidine incorporation), which ranged from 36 ng C l-1 d-1 in the overlying ice to 3329 ng C l-1 d -1 in the sediment-containing layers. Bacteria within both the sediments and overlying ice were able to actively incorporate and respire radio-labeled glucose, as well as 17 other dissolved organic carbon compounds. The cryoconites in the Taylor Valley support an active, diverse assemblage of organisms despite the fact that they may remain sealed from the atmosphere for decades. Given the density of the cryoconites in the dry valleys ( ~4–6% of ablation zone surfaces), flushing of the cryoconites during warm years could provide a vital nutrient and organic carbon source to the surrounding polar desert.