Doctoral Dissertation Research: A Paleolimnological Investigation of Climate and Nitrogen Impacts on Primary Producers in Greenland Lakes and Community Water Supplies

这一博士论文研究改进项目将利用古代湖泊沉积物记录来重建与北方社区特别相关的北极湖泊5000年来的生态系统变化史。尽管许多偏远的北极村庄依靠湖泊提供饮用水储备和农业灌溉等关键的生态系统服务，但这些小规模的供水没有得到足够的监测，对它们对气候和土地利用变化的敏感性进行的调查也很少。这项研究将探讨在数十年和数千年的时间尺度上，哪些因素，包括温度和营养输入，对北极湖泊中光合作用生物的生物生产力和多样性影响最大。这项研究的第二个目标是为博士生提供在美国科学家和北极土著社区之间建立国际合作方面的正式培训。这位博士生将促进美国和格陵兰之间的关系，作为合作研究职业生涯的基础，该研究结合当地和土著知识，造福北方社区。作为对北极地区变暖的回应，北极地区的气候变暖速度比全球趋势快了四倍，北极的景观正在“绿化”，生态系统，包括湖泊内的生态系统，正在变得更加富有成效。这项工作研究了温度变化和不断变化的氮循环在推动湖泊中藻类和蓝藻群落变化方面的作用。该项目采用了一种新的方法，通过量化大量的沉积颜料来评估生产率。作为替代品，色素有许多优势，包括它们的生物体类别或分类特异性，以及它们反映不产生坚硬宏大化石的生物体的能力，这是旨在了解蓝藻群落趋势的工作的特殊资产。量化不同生物的沉积色素既可以洞察是什么驱动了大量初级生产力，也可以表征初级生产者的个别群体可能做出的反应。这项研究将推进这种未得到充分利用的方法的使用，这种方法可能适用于许多地区，在这些地区，湖泊藻类或蓝藻群落的变化和/或富营养化是一个社会问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This doctoral dissertation research improvement project will use ancient lake sediment records to reconstruct 5,000-year histories of ecosystem changes in Arctic lakes that are of particular relevance to Northern communities. Though many remote Arctic villages rely on lakes for critical ecosystem services like drinking water reserves and agricultural irrigation, these small water supplies are insufficiently monitored and their susceptibility to changing climate and land use have been minimally investigated. This study will examine what factors, including temperature and nutrient inputs, have most influenced the biological productivity and diversity of photosynthetic organisms in Arctic lakes over multi-decadal and multi-millennial timescales. A second goal of this study is to provide formal training to the doctoral student in building international collaborations between U.S. scientists and Arctic Indigenous communities. The doctoral student will foster relationships between the United States and Greenland as a foundation for a career in collaborative research that incorporates local and Indigenous knowledge for the benefit of Northern communities. In response to warming in Arctic regions that outpaces global trends by four-fold, Arctic landscapes are “greening” and ecosystems, including those within lakes, are becoming more productive. This work examines the roles of temperature shifts and changing nitrogen cycling in driving changes in algal and cyanobacterial communities in lakes. This project employs a novel methodology to assess productivity through quantifying numerous sedimentary pigments. Pigments have many strengths as proxies, including their organism class or taxonomic specificity and their ability to reflect organisms that do not produce hard macrofossils, which are particular assets for work that aims to understand trends in cyanobacterial communities. Quantifying sedimentary pigments of different organisms can both provide insight on what drives bulk primary productivity and characterize how individual groups of primary producers might respond. This research will advance the use of this underutilized methodology, which is potentially applicable in many regions where changing lacustrine algal or cyanobacterial communities and/or eutrophication are a societal concern.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.