Collaborative Research: Biogeochemistry of Cyanobacterial Mats and Hyporheic Zone Microbes in McMurdo Dry Valley glacial meltwater streams

麦克默多干谷的冰川流有广泛的蓝藻垫，是固定的C和N的山谷的可能来源。该研究将研究短暂冰川流中的微生物垫与这些垫下面和附近的低流性土壤（湿润土壤区）的微生物群之间的相互作用。据推测，垫是重要的来源，有机碳和固定氮的土壤群落的潜流带，并释放溶解有机碳（DOC）和氮（DON），服务于整个干旱河谷生态系统。实地工作将包括观察和实验两个部分。将直接比较垫和微生物种群之间的自然再水化和干燥垫的地区，垫之间的地区在融化流的亚当斯和迈尔斯冰川在迈尔斯谷。将检查土壤微生物群的生理和系统发育指标。观测将包括土壤细菌对垫碳和氮固定、土壤呼吸和亮氨酸和胸苷吸收（分别作为蛋白质DNA合成的措施）、细菌密度及其分子生态学的估计。&实验操作将包括土壤的实验再润湿和微生物群落反应的时间过程的观察。 该研究将现代分子遗传学方法（ARISA-DNA指纹图谱和超深16S rDNA微生物系统发育分析）与地球化学相结合，以研究在这些极端环境中茁壮成长的微生物群落的多样性，生态学和功能。 该项目更广泛的影响包括研究生和博士后研究生的研究和教育机会。P.I. s将涉及本科生作为勤工俭学的学生和REU计划，并将参加教育和推广计划。

The glacial streams of the McMurdo Dry Valleys have extensive cyanobacterial mats that are a probable source of fixed C and N to the Valleys. The research will examine the interplay between the microbial mats in the ephemeral glacial streams and the microbiota of the hyporheic soils (wetted soil zone) underlying and adjacent to those mats. It is hypothesized that the mats are important sources of organic carbon and fixed nitrogen for the soil communities of the hyporheic zone, and release dissolved organic carbon (DOC) and nitrogen (DON) that serves the entire Dry Valley ecosystem. Field efforts will entail both observational and experimental components. Direct comparisons will be made between the mats and microbial populations underlying naturally rehydrated and desiccated mat areas, and between mat areas in the melt streams of the Adams and Miers Glaciers in Miers Valley. Both physiological and phylogenetic indices of the soil microbiota will be examined. Observations will include estimates of rates of mat carbon and nitrogen fixation, soil respiration and leucine and thymidine uptake (as measures of protein & DNA synthesis, respectively) by soil bacteria, bacterial densities and their molecular ecology. Experimental manipulations will include experimental re-wetting of soils and observations of the time course of response of the microbial community. The research will integrate modern molecular genetic approaches (ARISA-DNA fingerprinting and ultra deep 16S rDNA microbial phylogenetic analysis) with geochemistry to study the diversity, ecology, and function of microbial communities that thrive in these extreme environments. The broader impacts of the project include research and educational opportunities for graduate students and a postdoctoral associate. The P.I.s will involve undergraduates as work-study students and in REU programs, and will participate in educational and outreach programs.