LTREB: Collaborative Research: What Controls Long-term Changes in Freshwater Microbial Community Composition?

DNA测序和分子技术的最新发展使微生物的研究发生了革命性的变化，揭示了微生物的身份和遗传潜力，并在微生物生物多样性方面产生了新的生态概念。微生物物种的时空格局及其在自然生态系统中的作用受其扩散属性（如风或水）和当地生长条件的控制，但这些因素的相对重要性尚不清楚。这项研究将描述北极湖泊、溪流和土壤中微生物分布的这两个基本控制因素，并将揭示微生物物种种群的季节性、年度和长期变化与该地区正在发生的快速气候变化之间的关系。微生物生物多样性的复杂性质对于了解人类健康和疾病，以及了解全球变暖的后果非常重要。细菌和其他微生物最终控制着所有生态系统中二氧化碳和甲烷（强效温室气体）的产生。在北极地区，目前气温虽低但上升迅速，永久冻土融化，大量积累的有机物都为增加细菌呼吸（将有机物转化为二氧化碳）创造了成熟的条件。这些共同因素可能极大地改变区域和全球的碳预算，从而反馈到进一步的气候变化。该项目还将通过美国国家科学基金会教师研究经验项目、字母校园（K-12）项目以及其他基于实地的课程和指导项目为教学和推广做出贡献。

Recent developments in DNA sequencing and molecular technologies have revolutionized the study of microorganisms, revealing their identities and genetic potential, and spawning new ecological concepts in microbial biodiversity. Spatial and temporal patterns in microbial species and their roles in natural ecosystems are controlled by their dispersal attributes (e.g., whether by wind or water) and local growth conditions, but the relative importance of these factors is unknown. This research will characterize these two fundamental controls on the distribution of microbes in Arctic lakes, streams and soils, and will reveal how seasonal, annual and long-term shifts in the populations of microbial species relate to the rapid climatic changes that are occurring in this region. The complex nature of microbial biodiversity is important for understanding human health and disease, and for understanding the consequences of our warming world. Bacteria and other microbes ultimately control the production of carbon dioxide and methane, potent greenhouse gasses, in all ecosystems. In the Arctic there are currently low but rapidly increasing temperatures, thawing permafrost, and much accumulated organic matter all creating a situation ripe for increased bacterial respiration (conversion of organic matter to carbon dioxide). These collective factors could greatly alter regional and global carbon budgets, and hence feedback to further climate changes. This project will also contribute to teaching and outreach through the NSF Research Experience for Teachers program, the LTER-Schoolyard (K-12) program, and other field-based courses and mentoring programs.