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

气候变化正在推动地球（冰冻圈）上冰冻水数量的巨大变化。一个越来越被人们所认识到的与气候变化相互作用、加剧冰雪融化的因素是在雪表面开花的藻类（雪藻）的繁殖。目前对控制雪藻丰度的因素以及它们对冰雪融化的影响的理解是不完整的，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未得到充分研究的驱动因素-通过大气沉积（雪，雨和灰尘）的关键营养元素（氮和磷）的可变输入。该项目利用并发展了一个跨学科团队的能力，该团队涉及教师，博士后，研究生和本科生，该项目具有广泛的社会相关性，因为山区雪在全球供水中发挥着至关重要的作用。总的来说，这些研究将是第一个明确测试高山雪藻营养限制的研究，显著提高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损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”本科实地课程，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。公众宣传将包括与水资源利益相关者和管理人员的联系，以及通过现有的公众宣传渠道与更广泛的受众进行沟通。这项研究将研究氮和磷的投入对雪藻的影响，在美国西部的六个研究区域在整个梯度的大气养分沉积。该项目有三个焦点问题：1）雪藻生物量，生产力和碳：氮：磷比例与美国西部山区营养（氮，磷）沉积和可用性的模式有关？2)这些雪藻生态系统如何应对实验性的营养富集？3)营养素驱动的雪藻的增殖如何影响雪的生物学特性，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增殖（使用蒙大拿州立大学零度以下研究实验室的独特能力），并测试氮和磷的富集如何影响雪藻的生长及其在野外和实验室条件下对雪藻和融水的影响。研究这些问题将产生关于雪藻生态系统中营养限制作用的新的基本知识，以及营养投入和生物减少之间的联系，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投入和运输的过程提供基础。该项目还将支持冰冻圈生态学的跨学科课程的开发，包括雪科学，地球化学，微生物学和藻类学。该奖项反映了NSF的法定使命，并被认为值得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。

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.