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

气候变化正在推动地球(冰冻圈)上存在的冰冻水的数量发生巨大变化。与气候变化相互作用放大冰雪融化的一个日益广为人知的因素是雪面上大量繁殖的藻类(雪藻)。目前对控制雪藻丰度的因素及其对雪和冰融化的影响的了解是不完整的，特别是在高山环境中，冰川和雪地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研究不足的驱动因素--通过大气沉积(在雪、雨和尘埃中)对关键营养元素(氮和磷)的可变输入。鉴于山雪在全球供水中的关键作用，该项目利用并发展了一个由教师、博士后、研究生和本科生组成的跨学科团队的能力，该项目具有广泛的社会意义。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之一，大大加强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推动冰冻圈丧失方面的作用至关重要，这一过程最终对海平面上升和淡水供应产生重大影响。项目人员将开发和提供一个独特的“冰冻圈生态学”本科野外课程，该课程将整合生态系统生态学、微生物学和雪学的关键主题和概念。公众外展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外展渠道与更广泛的受众进行沟通。这项研究将研究美国西部六个研究地区跨大气养分沉积梯度的氮和磷输入对雪藻的影响。该项目有三个重点问题：1)雪藻生物量、生产力和碳/氮/磷比如何与美国西部山区的养分(氮、磷)沉积和有效性模式相关？2)这些雪藻生态系统如何响应实验中的养分增加？3)营养驱动的雪藻繁殖如何影响雪的反照率特性，从而加速雪融化？为了回答这些问题，该项目将评估雪藻如何在六个研究地区的融化水形成的雪中繁殖(利用蒙大拿州立大学零下研究实验室的独特能力)，并测试在野外和实验室条件下，氮和磷的增加如何影响雪藻的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和生物反照率减少之间的联系的新的基础知识，有助于更好地预测山区融雪驱动的供水，并为缓解推动大气污染物输入和传输的过程提供基础。该项目还将支持冰冻圈生态学跨学科课程的发展，包括雪学、生物地球化学、微生物学和植物学。这一奖项反映了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。

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.