RII Track-4: Paleoecological insights into the impacts of climate change on Vermont lakes

非技术描述佛蒙特州和其他北部州的小湖泊的水质受到湖中生长的水生植物类型的影响。以大型水生植物为主的湖泊能够保持相对稳定、清澈的水状态，而以藻类为主的湖泊更有可能遭受水质和生态系统健康下降的影响。控制一个湖泊是否以植物为主而不是以藻类为主的最重要因素是磷等营养物质的输入，由于人类活动，许多湖泊的磷含量都有所增加。温度和降水的年度和季节变化会放大水生植物生长中营养物质驱动的变化。面对气候变化的预测，这些短期气候影响增加了人们对湖泊长期水质的担忧。随着时间的推移，湖泊沉积物在湖泊底部层层累积，为研究过去气候变化与较长时间尺度上水生植物生长之间的动态提供了机会，并深入了解未来水生生态系统将如何受到气候变化的影响。来自佛蒙特州中部的湖泊沉积物样本包含关于沉积物和动植物化石的化学成分的数据，这些数据将被用来重建过去10,000年来气候和水生植物生长的变化。来自东北部的现有气候重建网络记录了过去的几个区域气候变化，这将为评估湖泊对温度和/或降水变化的反应提供一个背景。与怀俄明大学地质和地球物理系的合作将使人们能够获得关键分析，以及就数据分析的创新统计方法进行培训。该项目的结果将在诺维奇大学和怀俄明大学的研究人员之间建立强有力的合作，同时建立新的方法来调查过去的水生生态系统，并有助于更好地理解水生植物生长、水质和气候变化之间的长期联系。这项工作将为未来有关佛蒙特州湖泊保护的管理决策提供信息，并将为预测的气候变化将对宝贵的淡水资源产生的影响提供更多证据。技术说明由于营养物质负荷的增加，佛蒙特州湖泊和其他淡水资源的命运已成为核心环境问题。在小型湖泊中，营养盐负荷控制着浮游植物相对于大型植物的优势，是水质和生态系统健康的决定因素。大型植物促进清水状态，而浮游植物过多则导致水体浑浊和富营养化。除了营养负荷的变化外，鱼类种群的大小和组成、湖泊的大小和深度以及气候也有可能导致大型植物和浮游植物状态之间的转变。气候是这些因素中最不为人所知的，它在佛蒙特州提出了一系列重要的研究问题，在过去50年里，佛蒙特州的冬季和夏季平均气温和总降雨量都有所增加。这项研究将通过使用佛蒙特州中部的湖泊沉积岩心来重建全新世(距今10,000-0年)湖泊初级生产力和气候的过去变化，从而提供对这些问题的长期洞察。美国东北部全新世期间的温度和降水变化通过古生态遗址网络得到了很好的记录，并为研究气候作为水生生态系统变化驱动因素的作用提供了机会。佛蒙特州中部富含碳酸盐的湖泊包含多种沉积环境，保存着独特的替代数据集，这将使重建气候和古生产力的独立记录成为可能。这项工作将与怀俄明大学合作完成，并将使用地质系和地球物理系实验室内提供的一套沉积物和地球化学分析。此外，怀俄明大学的这位合作者还开发了分析多变量古生态数据的定量方法，这些方法将用于识别具有统计意义的变异性模式。在这次研究期间完成的工作将采用新的方法来重建过去湖泊生产力的变化，这些方法可能会被其他研究人员更广泛地采用，并将扩大古生态学在理解现代湖沼学过程中的应用。

Non-technical DescriptionThe water quality of small lakes in Vermont and other northern states is influenced by the types of aquatic plants growing in the lake. Lakes dominated by large aquatic plants are able to maintain a relatively stable, clear water state, while lakes dominated by algae are more likely to suffer from a decline in both water quality and ecosystem health. The most important factor controlling whether a lake is plant- versus algae-dominated is the input of nutrients such as phosphorous, which has increased in many lakes as a result of human activity. Annual and seasonal variations in temperature and precipitation can amplify nutrient-driven changes in aquatic plant growth. These short-term climatic impacts have increased concern over the long-term water quality of lakes in the face of predictions of climate change. Lake sediment, which accumulates in layers at the bottom of lakes through time, provides an opportunity to investigate the dynamics between past climate change and aquatic plant growth over longer time-scales and to gain insights into how aquatic ecosystems will be impacted in the future by climate change. Lake sediment samples from central Vermont contain data on the chemical composition of the sediment and fossils of plants and animals, which will be used to reconstruct changes in both climate and aquatic plant growth during the last 10,000 years. A network of existing climate reconstructions from the northeast documents several past regional climatic changes, which will provide a context for evaluating how lakes respond to changes in temperature and/or precipitation. Collaboration with the Department of Geology and Geophysics at the University of Wyoming will enable access to critical analyses, as well as training in innovative statistical approaches to data analysis. The results of this project will build a strong collaboration between researchers at Norwich University and the University of Wyoming while establishing new methods for investigating past aquatic ecosystems and contributing to a greater understanding of the long-term connections between aquatic plant growth, water quality, and climate change. This work will inform future management decisions concerning the conservation of Vermont's lakes and will provide additional evidence on the impact that projected climate change will have on valuable freshwater resources.Technical DescriptionThe fates of lakes and other freshwater resources in Vermont have become of central environmental concern due to increased nutrient loading. In small lakes, nutrient loading controls the dominance of phytoplankton versus macrophytes, and is a determinant of water quality and ecosystem health. Macrophytes promote a clear-water state while excessive phytoplankton leads to turbid-water and eutrophic conditions. In addition to changes in nutrient loads, fish population size and composition, lake size and depth, and climate, have the potential to induce a shift between macrophyte- and phytoplankton-states. Climate is the least well-understood of these factors and poses an important set of research questions in Vermont, where during the last 50 years, winter and summer mean annual temperatures and total precipitation have increased. This study will provide long-term insight into these issues by using lake sediment cores from central Vermont to reconstruct past changes in lake primary productivity and climate during the Holocene Epoch (10,000-0 years before present). Temperature and precipitation changes during the Holocene in the northeastern United States are well-documented by a network of paleoecological sites, and provide an opportunity to examine the role of climate as a driver of aquatic ecosystem change. Carbonate-rich lakes in central Vermont contain multiple depositional environments that preserve unique sets of proxy data that will enable the reconstruction of independent records of climate and paleoproductivity. This work will be done in collaboration with the University of Wyoming and will use a suite of sediment and geochemical analyses that are available within the Departments of Geology and Geophysics' laboratories. In addition, the collaborator at the University of Wyoming has developed quantitative approaches to analysis of multivariate paleoecological data that will be used to identify statistically significant patterns of variability. The work completed during this fellowship will employ novel approaches to reconstructing past changes in lake productivity that may be adopted more widely by other researchers and will expand the application of paleoecology to understanding modern limnological processes.