Are There Perennial and Light-Independent Microbial Processes on Supraglacial Ecosystems?#

即使在阳光普照的冰川表面，生命也欣欣向荣。但是冰上的生命能在北极黑暗的冬季和沉积物中存活吗？我们知道冰川表面是活跃的微生物生态系统的家园。我们知道，在夏季，这些光合作用驱动的生态系统固定碳和变暗的冰，因为太阳能被转化为暗有机碳。因此，冰川上的生态系统影响着我们正在变暖的世界中冰川的命运。到目前为止，生物地球化学家一直认为，只有在夏季短暂的融化季节，冰川上的生态系统才会在阳光和液态融水中的营养物质的滋养下才会活跃。这一限制限制了我们对冰川表面生态学的理解，以至于没有证据表明冬季冰川上有活跃的微生物过程，这被认为是它们不存在的证据。但我们现在有了全年的数据，这些数据有力地挑战了生命只在夏季活跃的假设。我们的试验数据还首次揭示了冰面上产生甲烷的现象。因此，这个项目测试了一个简单但有力的想法，即冰川表面栖息地长期活跃，导致了意想不到的温室气体来源。我们的项目建议解决我们对冰川生态理解中的三个相互关联的主要知识缺口。首先，我们需要知道什么东西在冬天生活，其次，我们需要知道什么生活在厚厚的冰层沉积物中，最后我们需要知道在黑暗中生存的微生物生命形式如何影响冰川上的碳循环和营养循环。我们项目的总体假设是，冰川表面拥有不依赖光的微生物代谢活动，因此允许微生物在意想不到的条件下活动，而忽略了对营养循环和温室气体产生的贡献。在这个项目中，我们将在每个季节前往斯瓦尔巴特群岛的北极高地冰川，比较它们在极夜深处、冬季寒冷、春季融化和盛夏时的微生物群落。我们将在每个冰川收集样本进行分子分析，并测量微生物的活动。我们将进行实验，以揭示微生物如何在这些条件下生存，以及它们如何与冰川的碳循环和营养循环相互作用。我们在英国、美国和挪威的冷实验室将实地工作与精心控制的孵化实验相结合。通过这样做，我们将第一次清楚地了解北极冰川上的生命是如何在所有季节中存活的，以及这对北极冰川生态意味着什么，因为它们在变暖的北极面临着不确定的未来。

Life thrives even on the sun-kissed surfaces of glaciers. But does life on ice survive in the darkened depths of Arctic winters and sediments?We know glacier surfaces are home to active microbial ecosystems. We know that in summer these photosynthesis-driven ecosystems fix carbon and darken ice as solar energy is converted to dark organic carbon. As a result, ecosystems on glaciers influence the fate of glaciers in our warming world. Until now, biogeochemists have assumed ecosystems on glaciers are only active when nourished with sunlight and nutrients in liquid meltwater in the brief melting season of summer. This constraint has framed our understanding of glacier surface ecology to the extent that the absence of evidence for active microbial processes on glaciers in winter has been considered evidence of their absence. But we now have year-round data which robustly challenges the assumption life is only active in summer. Our pilot data also reveals methane producers for the first time on ice surfaces. This project therefore tests the simple but powerful idea that glacier surface habitats are perennially active, resulting in unexpected sources of greenhouse gases.Our project proposes to address three interlinked major knowledge gaps in our understanding of glacier ecology. Firstly, we need to know what lives through the winter, secondly, we need to know what lives in thick accumulations of sediments on ice, and finally we need to know how the microbial life forms surviving through darkness influence carbon and nutrient cycles on glaciers. Our project's overall hypothesis is that glacier surfaces host light-independent microbial metabolic activities, thus allowing microbial activities in unexpected conditions with neglected contributions to nutrient cycles and greenhouse gas production. In this project we will go the High Arctic glaciers of Svalbard in every season to compare their microbial communities in the depths of polar night, the cold of the winter, the spring thaw and the height of summer. At each glacier we will collect samples for molecular analyses and measure microbial activities. We will conduct experiments to reveal how the microbes survive in these conditions, and how they interact with the carbon and nutrient cycles of the glaciers. We combine our fieldwork with carefully-controlled incubation experiments in cold labs in the UK, US and Norway. By doing this, we will have a clear picture for the first time of how life survives all seasons on Arctic glaciers and what this means for the ecology of Arctic glaciers as they face an uncertain future in the warming Arctic.