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Krzysztof Zawierucha, Marta Ostrowska and Małgorzata Kolicka

Abstract

For several years it has been of interest to astrobiologists to focus on Earth’s glaciers as a habitat that can be similar to glaciers on other moons and planets. Microorganisms on glaciers form consortia – cryoconite granules (cryoconites). They are granular/spherical mineral particles connected with archaea, cyanobacteria, heterotrophic bacteria, algae, fungi, and micro animals (mainly Tardigrada and Rotifera). Cryophilic organisms inhabiting glaciers have been studied in different aspects: from taxonomy, ecology and biogeography, to searching of biotechnological potentials and physiological strategies to survive in extreme glacial habitats. However, they have never been used in astrobiological experiments. The main aim of this paper is brief review of literature and supporting assumptions that cryoconite granules and microinvertebrates on glaciers, are promising models in astrobiology for looking for analogies and survival strategies in terms of icy planets and moons. So far, astrobiological research have been conducted on single strains of prokaryotes or microinvertebrates but never on a consortium of them. Due to the hypothetical similarity of glaciers on the Earth to those on other planets these cryoconites consortia of microorganisms and glacier microinvertebrates may be applied in astrobiological experiments instead of the limno-terrestrial ones used currently. Those consortia and animals have qualities to use them in such studies and they may be the key to understanding how organisms are able to survive, reproduce and remain active at low temperatures.

Open access

Krzysztof Zawierucha, Tobias R. Vonnahme, Miloslav Devetter, Małgorzata Kolicka, Marta Ostrowska, Sebastian Chmielewski and Jakub Z. Kosicki

Abstract

Water bears (Tardigrada) are known as one of the most extremophile animals in the world. They inhabit environments from the deepest parts of the oceans up to the highest mountains. One of the most extreme and still poorly studied habitats which tardigrades inhabit are cryoconite holes. We analysed the relation between area, depth, elevation and tardigrades densities in cryoconite holes on four glaciers on Spitsbergen. The mean (±SD) of cryoconite area was 1287.21±2400.8 cm2, while the depth was on average 10.8±11.2 cm, the elevation 172.6±109.66 m a.s.l., and tardigrade density 24.9±33.0 individuals per gram of wet material (n = 38). The densities of tardigrades on Hans Glacier reached values of up to 168 ind. cm3, 104 ind. g−1 wet weight, and 275 ind. g−1 dry weight. The densities of tardigrades of the three glaciers in Billefjorden were up to 82 ind. cm2, 326 ind. g−1 wet weight and 624 ind. g−1 dry weight. Surprisingly, although the model included area, depth and elevation as independent variables, it cannot explain Tardigrada density in cryoconite holes. We propose that due to the rapid melting of the glacier surface in the Arctic, the constant flushing of cryoconite sediments, and inter-hole water-sediment mixing, the functioning of these ecosystems is disrupted. We conclude that cryoconite holes are dynamic ecosystems for microinvertebrates in the Arctic.