LTREB Renewal: Collaborative research: What controls long-term changes in freshwater microbial community composition?

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Advances in DNA sequencing have revolutionized the study of microorganisms such as bacteria, revealing their genetic identity and ecological potential. Microbial communities carry out critical processes that regulate the amounts and forms of important nutrients and carbon, which are essential for all ecosystem services on Earth. Results from the first five years of this research program demonstrated that the biodiversity and activity of these communities varies tremendously among environments and over time. Microbial biodiversity and ecosystem functions are controlled (1) by local environmental conditions that affect growth, and (2) by dispersal via wind and water. However, the relative importance of these factors is still unknown. This research project will characterize these two fundamental controls on the distribution and activity of microbes in Arctic lakes, streams, and soils, and will reveal how seasonal, annual, and long-term shifts in microbial species are affected by climate change. This research will use the data archive of environmental measurements produced by the Arctic Long Term Ecological Research program (LTER), and will use next-generation DNA sequencing technology to assess microbial community composition and function.The goal of this research project is to measure shifts in microbial biodiversity, bacterial respiration, and ecosystem function associated with the current and dramatic environmental changes in the Arctic. Bacteria and other microbes ultimately control the production and consumption of the heat-trapping gases carbon dioxide and methane. In the Arctic, warming temperatures are thawing permafrost and exposing a vast store of previously-frozen organic carbon in soils. If this carbon is released to the atmosphere as heat-trapping gases the rate of climate warming will increase, further thawing the soils and exposing more carbon to microbial attack. The strength of this positive feedback loop is controlled by bacteria, because their respiration converts the soil carbon to carbon dioxide and methane which is then released to the atmosphere. In addition, this project will contribute to teaching and outreach through the NSF Research Experience for Undergraduates and Research Experience for Teachers programs, graduate student and postdoctoral scientist training, and collaboration with the Earth Microbiome Project (http://www.earthmicrobiome.org).