A bipolar comparison of glacial cryoconite ecosystems /

This thesis compares the habitat and community ecology of cylindrical meltholes from the surface of two polar glaciers. These holes (termed cryoconite holes) are formed when wind-blown dust gathers in small depressions in the ice causing vertical melting by absorption of more radiation than the surrounding ice. The communities are complex microbial consortia of heterotrophic bacteria, cyanobacteria, eukaryotic algae, and protists. 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). Water from Canada Glacier cryoconite holes contained significantly higher concentrations of nutrients and had higher pH values and conductivities, relative to the White Glacier meltwater. Cryoconite communities on the Canada Glacier were dominated by cyanobacteria, either coccoid or filamentous, while the White Glacier cryoconite holes showed an abundance of either saccoderm desmids or filamentous cyanobacteria. Canada Glacier communities were found to be associated with environmental gradients whereas White Glacier cryoconite ecosystems were not