DISSERTATION RESEARCH Temperature and Nutrient Control of Cyanobacterial Nitrogen Fixation in Subalpine Drainages: a mesocosm Experiment

氮是藻类和其他水生植物必不可少的营养物质。一些被称为蓝藻的藻类可以在一种被称为固氮的过程中利用大气中的氮。然而，我们对未受干扰的流域(如锯齿山脉荒野地区的流域)中的固氮发生在哪里甚至是否发生知之甚少(ID)。在这些流域中，温度和养分(氮和磷)浓度可能相互作用，以控制固氮的速度和位置。了解这些因素是如何控制固氮的尤为重要，因为全球变暖导致水温上升，人类干扰造成水污染。在我头三年的研究中，我专注于锯齿山湖泊和溪流中固氮的位置和营养控制。我现在提议使用溪边实验来测试温度和营养物质如何影响固氮率。蓝藻的反应将在3天、21天和42天后进行测量，以检查对营养和温度变化的短期和长期反应。这项实验将深入了解全球变暖如何影响水生生态系统的固氮。作为该项目的一部分，关于温度对水生生态系统的影响的公开演讲将在林业局营火讲座上进行，并将作为针对高中生的教育网络海报。

Nitrogen is an essential nutrient for algae and other aquatic plants. Some algae, called cyanobacteria, can use nitrogen from the atmosphere in a process called nitrogen fixation. However, we know very little about where or even if nitrogen fixation occurs in undisturbed watersheds such as those found in wilderness areas of the Sawtooth Mountains (ID). In these watersheds, temperature and nutrient (nitrogen and phosphorus) concentrations may interact to control rates and location of nitrogen fixation. Understanding how these factors control nitrogen fixation is particularly important as global warming increases water temperatures and human disturbances create water pollution. During my first three years of research I focused on the location and nutrient control of nitrogen fixation in Sawtooth Mountain lakes and streams. I now propose to use stream-side experiments to test how temperature and nutrients influence nitrogen fixation rates. Cyanobacteria responses will be measured after 3, 21, and 42 days to examine both short-term and long-term responses to nutrient and temperature alterations. This experiment will provide insight into how global warming may affect nitrogen fixation in aquatic ecosystems. As part of this project, public presentations about the effects of temperature on aquatic ecosystems will be made at Forest Service campfire lectures and as an educational web-based poster directed at high-school students.