3/8/2023 0 Comments Download ne version of 4peaksIce worms also appear occasionally in meltwater pools common within the ablation zone (e.g., cryoconite holes), which support multiple trophic levels across domains of life including apex meiofauna 16, 17, 18. These worms inhabit glacier ice above the equilibrium line altitude (ELA), which separates snow accumulation and ablation zones, respectively. Wright (1887) discovered the first glacially-obligate, multicellular animal-the glacier ice worm, Mesenchytraeus solifugus (phylum Annelida)–inhabiting Muir Glacier, Alaska 12, 13, thereafter reported on glaciers throughout the Pacific Northwest 14, 15. Permanently cold temperatures (0 ☌ and below), high UV radiation, nutrient-poor and hydrologically-limiting conditions constrain organismal diversity in this habitat to specialized psychrophilic taxa, predominantly single-celled microbes 8, 9, 10, 11. On maritime glaciers, those most threatened by our changing global climate 5, 6, 7, ultrathin films of water fill these veinous aquifers and provide a microenvironment for extremophilic life. Prior to compression, however, upper layers of ice (i.e., weathered surface and several metres below) maintain ultrastructural spaces between crystal interfaces, forming arrays of microchannels that connect with the glacial surface 3, 4. The cumulative weight of overlying snow/ice compresses deep subsurface ice to densities > 900 kg/m 3, effectively excluding physical space for even the smallest single-celled microbes 1, 2. Glacier ecosystems are an inhospitable environment for most animals.
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