Nematodes and rotifers on two Alpine debris-covered glaciers

Abstract

Debris-covered glaciers (DCGs) are glaciers whose ablation area is mostly covered by a continuous layer of debris, and are considered to be among the continental glacierized environments richest in life. DCG colonization by microorganisms, plants and animals, has been investigated in a few studies, while the meiofauna (metazoans smaller than 2 mm) of these environments has been neglected so far. In this study, we analyzed nematode and rotifer fauna on the two largest debriscovered glaciers of the Italian Alps: the Miage Glacier and the Belvedere Glacier. In total, we collected 38 debris samples on the glaciers in July and September 2009. All the rotifers we found belonged to the bdelloid Adineta vaga (Davis, 1873). Nematodes belonged to 19 species. Miage Glacier hosted a richer and more diverse nematode fauna than the Belvedere. The dominant genus was Plectus Bastian, 1865, a common genus in habitats at high latitude and altitude. Analysis of the feeding type of nematodes highlighted that bacterivores were dominant on Miage Glacier, while bacterivores and herbivores were more widespread on Belvedere Glacier. Predator nematodes were absent. Analysis of the food-web structure indicated that nematode assemblages on both glaciers were typical of environments with depleted food availability, probably resulting from instability of the glacier surface and the short exposure of sediments, preventing the evolution of true soil and enrichment in organic matter of the debris. The scarcity of bacterial primary producers suggests that deposition of allochthonous organic matter is the principal organic carbon source in this environment.

A hole in the nematosphere: tardigrades and rotifers dominate the cryoconite hole environment, whereas nematodes are missing

“…For instance, nematodes survive freezing and desiccation in Antarctic soils through dormancy but reproduce when water and temperature conditions are favourable (Wharton, 2003). The presence of nematodes overlying glaciers in supraglacial debris (Azzoni et al ., 2015) and in glacier mice (Coulson & Midgley, 2012) indicates the presence of these favourable conditions in these habitats. Overhoff, Freckman & Virginia (1993) found that temperatures of 10°C were required for growth of Scottnema lindsayae , the most dominant Antarctic nematodes adapted to cold soils – a temperature unlikely achieved in ice‐bound cryoconite holes.…”

“…Nematodes have been reported in supraglacial gravel in the Alps by Azzoni et al . (2015) and in moss balls (so‐called ‘glacier mice’) in Iceland by Coulson & Midgley (2012). Additionally, Schwarz et al .…”

Ecosystem Birth near Melting Glaciers: A Review on the Pioneer Role of Ground-Dwelling Arthropods

“…In four-year-old soil at Hardangerjøkulen glacier in Norway, both Nematoda, Tardigrada, and Rotifera have been documented (Magnusson, Willassen and Hågvar, unpublished). Nematoda and Rotifera have been studied on supraglacial debris of two Alpine debris-covered glacier [70].…”

Life in harsh environments: carabid and spider trait types and functional diversity on a debris‐covered glacier and along its foreland

“…Spatial distribution of ground-dwelling arthropods is mainly determined by site age (time since deglaciation), with its related local fine-scale environment conditions, such as soil grain size, vegetation cover, and/or soil organic matter (see, Kaufmann, 2001;Brambilla & Gobbi, 2014;Tampucci et al, 2015). More recently, attention has shifted from the glacier forelands to the surface of debris-covered glaciers, because of the emerging interest of debris-covered glaciers as suitable habitats for micro-, meso-and macro-fauna and plant life (Caccianiga et al, 2011;Gobbi et al, 2011;Azzoni et al, 2015). Debris-covered glaciers are formed by frequent slipping and casting of deposits creating large quantities of stony material which covers the glacier surface, in particular on the ablation area (Citterio et al, 2007), and these have increased significantly during the last decade.…”