ARCUS | Arctic Research Consortium of the United States

6th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Derek Mueller
Authors   Derek R. Mueller, W.F. Vincent, W.H. Pollard, and C.H. Fritsen
Category   Life Science
Title   Glacial cryoconite ecosystems: a bipolar comparison of algal communities and habitats
Affiliation   Département de biologie, Université Laval, Sainte-Foy, QC, Canada

Abstract

Meltwaters on glaciers contain a variety of aquatic biota, particularly within the habitat formed by cryoconite holes in the glacial ablation zone. These holes consist of cylindrical cavities filled with meltwater and a basal layer of dark sediment. They are initiated when wind-blown dust gathers in small depressions in the ice and causes vertical melting by absorbing more radiation than the surrounding ice. These holes are typically 10-50 cm deep and provide a suitable habitat for microbial colonization, growth and succession. The communities are complex microbial consortia of heterotrophic bacteria, cyanobacteria, eukaryotic algae, and protists, and may also contain micro-invertebrates such as tardigrades and rotifers. We undertook a bipolar comparison to evaluate whether there are biogeographical differences between the two polar regions in this type of cryo-ecosystem. Samples were taken from cryoconite holes on Canada Glacier, Taylor Valley, Antarctica (77°37’S, 162°55’E) and on White Glacier, Axel Heiberg Island, Nunavut Territory, Canada (79°27’N, 90°40’W). The two sites have approximately the same mean annual temperature, although the White Glacier has higher summer temperatures. Water from Canada Glacier cryoconite holes contained significantly higher concentrations of ammonia, nitrate and DRP. The pH of White Glacier water was significantly below that for the Canada Glacier meltwaters, possibly reflecting the anthropogenic input of acidic materials via the north polar atmosphere. Communities from Canada Glacier were dominated by cyanobacteria (either Chroococcales or Oscillatoriales). Two species of saccoderm desmids plus oscillatorian cyanobacteria were prominent in White Glacier cryoconite holes. Communities from both glaciers also contained heterotrophic bacteria, flagellates, ciliates, rotifers and tardigrades. These results indicate a high prokaryotic and eukaryotic biodiversity despite the extreme nature of the glacial meltwater habitat.