Algivorous Cercozoa shape the community composition of cryptogamic covers, the dominant vegetation in Polar Regions.

原核生物及其真核生物消费者的捕食-被捕食动态一直是微生物生态学研究的重点，但微生物与真核生物的相互作用研究较少。微藻在南极洲的海洋和淡水生态系统中扮演着初级生产者的关键角色，几乎所有的能量和营养物质都通过藻类输送到这里的更高营养水平。相比之下，在这种情况下，南极洲的陆地生态系统尚未得到研究。陆地植被通常以维管植物为初级生产者，但南极的陆地植被以隐性盖层(如生物壳)为主，其中蕴藏着丰富的陆生藻类。南极半岛高达55%的植被陆地表面和北极斯瓦尔巴群岛70%的植被陆地表面被生物土壤结皮(生物结壳)覆盖；考虑到极地地区预计将变暖，这些数字预计会增加。“北极绿化”)由于气候变化。因此，很大一部分极地初级生产预计将由高纬度的生物灰藻进行。然而，这种能量如何被引导到更高的营养水平还没有被探索，特别是考虑到南极洲食铝后生动物的稀缺。尾丝虫是陆地生境中最丰富的单细胞真核生物(原生动物)之一，初步结果表明：在极地地区的生物壳中占主导地位的是食性尾丝虫。我们将首次阐明生物壳中作为主要初级生产者的藻类和最重要的食肉动物之间的捕食-被捕食关系，以补充两个极地地区的土壤微生物食物网。为此，我们将结合基于条形码的高通量Illumina调查和基于特征的数据分析，并辅之以传统的基于培养的实验，以获得基于微藻和尾藻的捕食者-猎物关系的全面图像，从而首次研究它们在南极和北极陆地生态系统中的结构和功能。这样的数据将有助于提出这样的问题：土壤微生物食物网在极地地区有多大的相关性，全球变暖是否有可能改变这些相互作用？

Predator-prey dynamics of prokaryotes and their eukaryotic consumers have long been in focus of microbial ecology, but microbial eukaryote-eukaryote interactions were less investigated. Microalgae play the key role as primary producers in marine and freshwater ecosystems of Antarctica and almost all energy and nutrients are channelled here via algae to higher trophic levels. In contrast and in this context, terrestrial ecosystems of Antarctica are unstudied. Terrestrial vegetation is usually dominated by vascular plants as primary producers, but the terrestrial vegetation of Antarctica is dominated by cryptogamic covers (like biocrusts), and the abundant terrestrial algae within. Up to 55% of the vegetated land surface on the Antarctic Peninsula and 70% of the vegetated land surface on Arctic Svalbard is covered by biological soil crusts (biocrusts); these numbers can be expected to increase considering a predicted warming of the Polar Regions (e.g. “Arctic Greening”) due to climate change. A significant proportion of polar primary production can thus be expected to be conducted by biocrust algae at high latitudes. Nevertheless, it is unexplored how this energy is channelled to higher trophic levels, especially when considering the scarcity of algivorous metazoans in Antarctica. Cercozoa are one of the most abundant unicellular eukaryotes (protists) in terrestrial habitats, and as preliminary results show: Algivorous Cercozoa dominate biocrusts in Polar Regions. We will illuminate for the first time predator-prey relationships in biocrusts between algae as main primary producers and the most important algivores to complement the soil microbial food web in both Polar Regions. For this we will combine barcoded-primer based high through-put Illumina surveys coupled with trait-based data analyses and complemented with traditional culture-based experiments to obtain a comprehensive picture based on predator-prey relations of microalgae and Cercozoa, thereby addressing for the first time their structure and function in terrestrial ecosystems of Antarctica and the Arctic. Such data will contribute to the questions how relevant the soil microbial food-web is in the Polar Regions and whether global warming has the potential to change these interactions?