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Research Objectives:
The antarctic Dry Valleys forms the driest and coldest ecosystem known and has, until relatively recently, been thought to harbor little life. This ecosystem is composed of a mosaic of glaciers, glacial streambeds, exposed soils, and the only permanently ice-covered lakes on Earth. The permanent ice eliminates wind-driven mixing resulting in vertical transport at the level of molecular diffusion, gas exchange between liquid water and the atmosphere, and reduces light penetration. The lakes present the only habitat in this ecosystem that contains permanent liquid water and supports year-round metabolic activity in an environment that would normally appear to be inhospitable to life. The food web of the lakes is dominated by prokaryotes and protists; few metazoans have been observed. Biogeochemical studies on these lakes have revealed many biogenic chemical gradients (e.g., N2O, CH4, DMS, DMSO) that lack simple biochemical and thermodynamic explanations.
These data beg one to ask if the microorganisms present in the water columns today are responsible for the geochemical gradients we now observe. A primary reason for establishing a MO for the dry valley lakes is to understand not just how the environment controls the diversity of organisms, but also how diversity itself controls the functioning of ecosystems. This is one of the hottest topics in modern ecological research and the lake systems lend themselves to answering these questions in a unique way. Given the lack of metazoans, and the evolutionary history and resultant geochemistry of these lakes, they offer a unique experimental arena to search for novel microorganisms and study the interplay of microbial diversity and ecosystem function.
This project will use molecular tools in concert with conventional and high throughput culturing techniques to define representative prokaryotic groups responsible for the contemporary redox couples and geochemical gradients that now exist in Lakes Fryxell and Bonney. These data will be integrated with prokaryotic based exoenzyme signatures and physiological traits to link prokaryotic diversity with ecosystem function. By working closely with the McMurdo LTER (Long Term Ecological Research), project team members will form a very diverse group representing fields that have not often worked together in the past (glaciologists, geochemists, hydrologists, meteorologists, microbial ecologists, molecular biologists, traditional microbiologists, modelers).
Given the sensitive and relatively simple systems in the dry valleys, this integrated approach will point the way towards a broader integration of the biogeosciences. The results will be significant to the growing bodies of literature in organismal diversity, biotechnology, geobiology, polar ecology, and astrobiology. The group will work with existing and proposed new programs to archive its phylogenetic and physiological data so that all interested can access it easily through the Internet. By linking this research with highly visible education, outreach and human diversity programs supported by NSF-OPP and the McMurdo LTER, this project will have a broad impact on society.
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