Stable isotopic composition of top consumers in Arctic cryoconite holes: revealing different position in supraglacial trophic network

• Main Authors: Jaroměřská, Tereza, Trubač, Jakub, Zawierucha, Krzysztof, Vondrovicová, Lenka, Devetter, Miloslav, Žárský, Jakub D.
• Format: Text
• Language: English
• Published: 2020
• Subjects: Arctic; Svalbard; glacier
• Online Access: https://doi.org/10.5194/bg-2020-46; https://www.biogeosciences-discuss.net/bg-2020-46/

Cryoconite holes are ecosystems on the glacier surface characterized by dynamic nature and truncated food webs. It is acknowledged that cryoconite holes play an important role being biodiversity hot-spots and factories for organic matter on glaciers. The most common cryoconite apex consumers are the cosmopolitan invertebrates – tardigrades and rotifers. Several studies have highlighted the relevance of cryoconite tardigrades and rotifers to cryoconite holes’ ecosystem functioning. However, due to the dominant occurrence of prokaryotes on glaciers, these consumers are usually out of the major scope of most studies aiming at biological processes on glaciers. The aim of this study is to present data about isotopic composition of tardigrades, rotifers and cryoconite from three High Arctic glaciers in Svalbard and discuss their potential trophic relations. We found that tardigrades have lower δ 15 N values than rotifers, which indicates different food requirements of both consumers. The δ 13 C values revealed similarities among the consumers from the same glaciers and differences between consumers and cryoconite among glaciers. The resulted δ 13 C values point to similar carbon requirement of consumers within a glacier but differences in carbon input between glaciers. The results comprise the first observation of cryoconite holes’ consumers through stable isotopic analyses using an improved method of cryoconite sample processing and pave the way for further studies of the supraglacial trophic network.