The microorganisms of cryoconite holes (algae, Archaea, bacteria, cyanobacteria, fungi, and Protista): a review

Abstract

We provide a comprehensive list of microorganisms (algae, Archaea, bacteria, cyanobacteria, fungi, and Protista) inhabiting cryoconite holes on glaciers throughout the world, giving an updated taxonomy accompanied by geographic coordinates and localities. The list consists of 370 taxa reported from cryoconite holes (mostly from Arctic and Antarctic regions and European Alps). However, most of the taxa were not identified to the species level. Until now only 39 identified species or subspecies of bacteria and Archaea, 11 fungi, 17 cyanobacteria, 62 algae, and 13 Protista are known from cryoconite holes, which are only about 38% of total number of taxa reported from these ephemeral environments. Almost 62% of the taxa were marked as cf. (confer) or were identified only to the genera or even to the higher taxonomic units (such as families or orders). This wide and detailed review assists other scientists to identify the gaps in our knowledge about cryobionts and indicates directions for further zoogeographical and taxonomical studies in this unique freshwater habitat.

Diversity and distribution of Tardigrada in Arctic cryoconite holes

“…Thus, they cannot be fortuitous elements on glaciers and certainly have adaptations and strategies like other glacier inhabitants (Price, 2000;Zawierucha et al, 2015a;Singh et al, 2014). Secondly, the presence of different trophic groups (herbivores, microbivores, and higher-level consumers) is not possible without the presence of autotrophs, which commonly inhabit glaciers (Kaczmarek et al, 2016). Therefore, glacial ecosystems on Spitsbergen are typified by truncated food webs.…”

“…Besides, glaciers also constitute an important habitat for microorganisms (Porazińska et al, 2004;Hodson et al, 2008;Edwards et al, 2011;Kaczmarek et al, 2016;Zawierucha et al, 2015a), which is why glaciers and ice sheets can be treated as a distinct glacial biome where cryoconite holes make up small ecosystems (Anesio and Laybourn-Parry, 2012). Cryoconite holes are water-filled reservoirs that occur on glacier surfaces throughout the world.…”

“…The development and functioning of these habitats is possible because of the decrease in albedo on the surfaces of mineral and organic dust-covered glaciers, the presence of cryophilic microorganisms and the existence of simple trophic webs (McIntyre, 1984;Takeuchi et al, 2001;Hodson et al, 2008;Zawierucha et al, 2015a;Cook et al, 2016b). Cryoconite holes are still poorly known extreme habitats, therefore the interest in them is increasing, especially in biological sciences (Dabert et al, 2015;Bagshaw et al, 2016aBagshaw et al, , 2016bCook et al, 2016aCook et al, , 2016bKaczmarek et al, 2016). Svalbard archipelago is the most glaciated region of the European Arctic (Hagen, 1993).…”

Applicability of cryoconite consortia of microorganisms and glacier-dwelling animals in astrobiological studies

“…Tanabe et al 2008;Bielewicz et al 2011). In cryoconite granules the most abundant groups of organisms are archaea, cyanobacteria, heterotrophic bacteria, algae, fungi, and protists (Kaczmarek et al 2015). Glacier extremophiles possess lipids and produce anti-freeze proteins and extracellular polymeric substances (EPS), which serve as cryo-and osmo-protectants (Feller and Gerday 2003;Boetius et al 2015).…”

Area, depth and elevation of cryoconite holes in the Arctic do not influence Tardigrada densities

“…Mueller et al 2001;Fountain et al 2004;Hodson et al 2008). The functioning of such habitats is possibly caused by a decrease in the albedo on the surface of a cryoconite-covered glacier and by the presence of various groups of microorganisms (McIntyre 1984;Takeuchi et al 2001;Hodson et al 2010;Kaczmarek et al 2016). Pioneer observations and studies of cryoconite holes took place in Greenland between the 19 th and 20 th century (Drygalski 1897) and have continued through present day.…”