Arctic cryoconite holes represent highly biologically active aquatic habitats on the glacier surface characterized by the dynamic nature of their formation and functioning. The most common cryoconite apex consumers are the cosmopolitan invertebrates – tardigrades and rotifers. Several studies have highlighted the potential relevance of tardigrades and rotifers to cryoconite holes' ecosystem functioning. However, due to the dominant occurrence of prokaryotes, these consumers are usually out of the major scope of most studies aimed at understanding biological processes on glaciers. The aim of this descriptive study is to present pioneering data on isotopic composition of tardigrades, rotifers and cryoconite from three High Arctic glaciers in Svalbard and discuss their role in a cryoconite hole trophic network. We found that tardigrades have lower δ¹⁵N values than rotifers, which indicates different food requirements or different isotopic fractionation of both consumers. The δ¹³C values revealed differences between consumers and organic matter in cryoconite among glaciers. However, the mechanistic explanation of these variations requires further investigation focused on the particular diet of cryoconite consumers and their isotopic ratio. Our study introduces the first observation of carbon and nitrogen stable isotopic composition of top consumers in cryoconite holes analysed by an improved method for cryoconite sample processing, paving the way for further studies of the supraglacial trophic network.

中文翻译：

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北极冰锥洞中顶级消费者的稳定同位素组成：揭示了超冰质营养网络中的不同作用

北极冰冻洞代表冰川表面上具有高度生物活性的水生生境，其特征是其形成和功能的动态性质。最常见的冰冻土顶点消费者是世界性的无脊椎动物–缓步动物和轮虫。几项研究强调了缓坡和轮虫与冰冻洞的生态系统功能的潜在相关性。但是，由于原核生物占主导地位，因此这些消费者通常不在旨在了解冰川生物过程的大多数研究的主要范围之内。这项描述性研究的目的是提供斯瓦尔巴特群岛三座高北极冰川的缓速器，轮虫和冰晶石的同位素组成的开创性数据，并讨论它们在冰晶岩孔营养网络中的作用。δ ¹⁵比轮虫，这表明不同的食物的要求或两者的消费者不同的同位素分馏的N值。的δ ¹³ C值揭示于冰尘冰川之间消费者和有机物之间的差异。但是，对这些变化的机理解释需要进一步研究，重点放在冰冻黑岩消费者的特殊饮食及其同位素比上。我们的研究首次介绍了使用改进的冰晶岩样品处理方法分析的冰晶岩孔中顶级消费者碳和氮稳定同位素组成的方法，这为进一步研究超冰晶营养网络铺平了道路。