Collaborative Research: Testing for nutrient limitation in alpine snow algae ecosystems

气候变化正在导致地球上的冰冻水（冰冻圈）发生巨大变化。越来越多的人认识到，与气候变化相互作用、放大冰雪融化的一个因素是在雪表面开花的藻类（雪藻）的增殖。目前对控制雪藻丰度的因素及其对冰雪融化的影响的了解是不完整的，特别是在高山环境中，冰川和雪原是供水的关键组成部分，特别容易受到气候变化的影响。该项目将研究雪藻丰度的一个重要但尚未得到充分研究的驱动因素——通过大气沉积（雪、雨和灰尘）输入的关键营养元素（氮和磷）的变量。该项目利用并发展了一个跨学科团队的能力，该团队包括教师、博士后、研究生和本科生，该项目具有广泛的社会相关性，考虑到山区积雪在全球供水中的关键作用。总的来说，这些研究将是第一批明确测试高山雪藻营养限制的研究，大大提高了目前对营养供应如何驱动冰冻圈大规模生态系统动态的理解。特别是，这些信息对于理解和预测雪藻在驱动冰冻圈损失中的作用至关重要，这一过程最终对海平面上升和淡水供应产生重大影响。项目人员将开发并提供一门独特的“冰冻圈生态学”本科实地课程，该课程将整合生态系统生态学、微生物学和雪科学的关键主题和概念。公共宣传将包括与水资源利益相关者和管理者的接触，以及通过现有的公共宣传渠道与更广泛的受众进行沟通。本研究将考察氮和磷输入对美国西部6个研究区域的雪藻的影响，跨越大气养分沉积的梯度。该项目有三个重点问题：1)美国西部山区的雪藻生物量、生产力和碳、氮、磷比与营养物（氮、磷）沉积和可利用性的关系如何？2)这些雪藻生态系统对实验营养盐的富集反应如何？3)营养物驱动的雪藻的增殖如何影响雪的反照率，从而加速雪的融化？为了回答这些问题，该项目将评估雪藻如何在六个研究区域的融水形成的雪中繁殖（利用蒙大拿州立大学零度以下研究实验室的独特能力），并测试氮和磷富集如何影响雪藻生长及其对反照率和融化的影响。回答这些问题将产生关于营养限制在雪藻生态系统中的作用以及营养输入与生物反照率降低之间的联系的新的基础知识，促进更好地预测山区融雪驱动的供水，并为减缓驱动大气污染物输入和运输的过程提供基础。该项目还将支持开发冰冻圈生态学的跨学科课程，包括雪科学、生物地球化学、微生物学和生理学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Climate change is driving massive changes in the amount of frozen water present on Earth (the cryosphere). An increasingly well-recognized factor that interacts with climate change to amplify the melting of ice and snow is the proliferation of algae that bloom on the snow surface (snow algae). Current understanding of the factors that control the abundance of snow algae, and thus their impact on snow and ice melt, is incomplete, especially in alpine environments where glaciers and snowfields are critical components of the water supply and are particularly susceptible to climate change. This project will examine an important but understudied driver of snow algae abundance – the variable input of key nutrient elements (nitrogen and phosphorus) via atmospheric deposition (in snow, rain, and dust). This project leverages and develops the capacities of an interdisciplinary team involving faculty, a postdoctorate, a graduate student, and undergraduates in a project of broad societal relevance given the crucial role of mountain snow in water supplies globally. Collectively, these studies will be among the first to explicitly test for nutrient limitation of alpine snow algae, significantly enhancing current understanding of how nutrient supplies drive large-scale ecosystem dynamics in the cryosphere. In particular, this information is critical for understanding and forecasting the role of snow algae in driving cryosphere loss, a process that ultimately has major impacts on sea level rise and freshwater supply. Project personnel will develop and deliver a unique “Cryosphere Ecology” undergraduate field class that will integrate key topics and concepts in ecosystem ecology, microbiology, and snow science. Public outreach will include contacts with water resource stakeholders and managers as well as communication to broader audiences via existing public outreach channels.This research will examine the impacts of nitrogen and phosphorus inputs on snow algae in six study regions in the western USA across a gradient of atmospheric nutrient deposition. The project has three focal questions: 1) How are snow algae biomass, productivity, and carbon:nitrogen:phosphorus ratios related to patterns of nutrient (nitrogen, phosphorus) deposition and availability in mountains of the western USA? 2) How do these snow algae ecosystems respond to experimental nutrient enrichment? 3) How does proliferation of nutrient-driven snow algae affect albedo properties of snow and thus accelerate snow melt? To answer these questions, this project will assess how snow algae proliferate in snow formed from meltwater from the six study regions (using the unique capacity of the Subzero Research Laboratory at Montana State University) and test how nitrogen and phosphorus enrichment affect snow algae growth and its impact on albedo and melting under both field and laboratory conditions. Answering these questions will produce novel fundamental knowledge of the role of nutrient limitation in snow algae ecosystems and the connection between nutrient inputs and biological albedo reduction, facilitating better forecasting of snowmelt-driven water supplies in mountain regions and providing a basis for mitigating processes that drive inputs and transport of atmospheric pollutants. The project will also support development of an interdisciplinary course in cryosphere ecology, encompassing snow science, biogeochemistry, microbiology, and phycology.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.