Greenland has been estimated to contribute towards ~7% of the world’s suspended sediment flux. At Leverett Glacier, in the southwest of the Greenland ice sheet, approximately 1011 microbial cells per cubic meter of meltwater are exported alongside these sediments. These cells and sediments are mostly sourced from the subglacial environment, and the Leverett Glacier river channels them to the downstream fjord with minimal changes to their community composition.
A new study has just been published in Microbial Ecology, co-authored by Marek, that investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers of sediments within the Leverett Glacier river delta. The research was a collaboration between the Geological Survey of Denmark and Greenland and the Universities of Copenhagen and Prague, and part of our subglacial carbon project.
We established a long-term incubation experiment using Leverett River delta sediment under anaerobic conditions. We detected sulphate depletion and a shift in the microbial community to a predominance of Desulfosporosinus meridiei, providing evidence for sulphate reduction. We also found evidence of methanogenesis in CO2/H2-amended incubations, likely performed by methanogenic Methanomicrobiales- and Methanosarcinales-related organisms. Later, a reduction in methane was observed to be paired with the depletion of sulphate, and we hypothesise that sulphate reduction out competed hydrogenotrophic methanogenesis. The structure and diversity of the original CO2/H2-amended incubation communities changed dramatically with a major shift in predominant community members and a decline in diversity and cell abundance. These results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.
Cameron KA, Stibal M, Olsen NS, Mikkelsen AB, Elberling B, Jacobsen CS (2017) Potential activity of subglacial microbiota transported to anoxic river delta sediments. Microbial Ecology doi: 10.1007/s00248-016-0926-2