LEXEN: Ecology of Microbial Systems in Extreme Environments: The Role of Nanoflagellates in Cold and Nutrient-Poor Arctic Freshwaters

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In one extreme freshwater environment, a long-term research site in arctic Alaska, a large amount of information about microbial communities and their ecology has been accumulated. The least known member of this, and most other microbial communities, is the single cell eukaryotes. This LExEN project will investigate the ecology, physiology, and evolution of nanoflagellates, and important member of the aquatic microbial system. There will be extensive cooperation with two funded projects, one on freshwater ecology and one on flagellate evolution. * With the large ecological project this new research will extend knowledge of nanaflagellates in their natural habitat of arctic lakes and ponds with an emphasis on their adaptation to cold and freezing conditions. * Diversity of protists and of their evolutionary relationships will be studies. In addition, microaerophilic environments will be examined to look for amitochondriates flagellates, basic knowledge of lineages basal to all other eukaryotes. LExEN additions to this existing understanding of the microbial system will focus on the biology and ecology of the nanoflagellates, the main predator of the aquatic bacteria. Protists from a shallow pond that freezes solid each year and from a deep arctic lake with a 9-month ice cover will be intensively sampled during the winter, spring, summer and fall. Results will include: * The identity of the nanoflagellates present, their seasonal abundance, distribution, and succession with microscopic and molecular methods (including probes targeting ribosomal RNA for species in samples from the field). * The reconstruction from rRNA sequences of the evolutionary relationships among the flagellates present in these extreme environments including the microaerophilic layers of sediment. The data base will enable further research on these virtually unknown organisms. * The physiology of organisms cultured from this extreme environment with emphasis on the effects of cold and freezing on their feeding behavior and on their respiration and survival during starvation. The experiments will examine flagellate adaptations for survival in cold waters and in frozen sediments.