Communities of algae and cyanobacteria on glaciers in west Greenland

Communities of algae and cyanobacteria on two glaciers in west Greenland (the Qaanaaq and Russel glaciers) were analyzed and compared with the aim of explaining why the Qaanaaq Glacier (in northwestern Greenland) has a dark-colored surface in satellite images whereas the Russel Glacier (in western central Greenland) has a light-colored surface. We found that algal and cyanobacterial communities differed between the glaciers and that the amount of biomass was higher on the colder glacier (Qaanaaq Glacier). The community on the Qaanaaq Glacier was composed mainly of green algae, whereas that on the Russel Glacier was dominated by cyanobacteria. Despite the shorter melting period (due to colder air temperature) for the Qaanaaq Glacier, the biovolume of algae and cyanobacteria was 2.35 times higher than that on the Russel Glacier at a similar altitude, suggesting greater primary production on the Qaanaaq Glacier. We discuss the possible effects of temperature, nutrient concentrations, and cryoconite holes (melt-holes in the glacier) on the community structure and productivity of algae and cyanobacteria on each glacier, and consider the influence of the identified differences in algal and cyanobacterial communities on the amount of surface melt.