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

Abstract

Abstract. 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 δ15N values than rotifers, which indicates different food requirements of both consumers. The δ13C values revealed similarities among the consumers from the same glaciers and differences between consumers and cryoconite among glaciers. The resulted δ13C 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.

Trophic and symbiotic links between obligate-glacier water bears (Tardigrada) and cryoconite microorganisms

“…Zawierucha et al [ 17 ] and Buda et al [ 22 ] did not find any clear trophic relationship between primary producers and grazers in cryoconite holes on the margin of the Greenland Ice Sheet (Russel Glacier) or on a maritime Antarctic glacier, respectively. In contrast, Jaromerska et al [ 28 ], using stable isotope ratios, revealed different use of food sources by tardigrades and rotifers in High Arctic cryoconite holes, although the food sources were unidentified. These studies were not able to present robust and clear relationships between grazers, their food sources and other biota.…”

Snow Algae Blooming Are Benefitable for Microinvertebrates Assemblages (Tardigrada and Rotifera) on the Seasonal Snow Patches in Japan

“…There are two potential scenarios which might explain this unrecognized pattern in cryoconite holes. In comparison with areas of snow algae blooming, cryoconite holes host very diverse biota and rich organic matter, thus diet of invertebrates might be complex which may constrain understanding of food preferences 45 . Secondly, dynamic nature of cryoconite holes in Arctic and alpine regions like rapid ablation, inter-hole watersediment mixing and stochastic weather events disturb or sometimes destroy habitats on surface of ice like cryoconite holes 30,46 , hence in dynamic habitats ndings of any ecological relations are problematic.…”