| description |
Tropospheric nitrate levels are predicted to increase throughout the 21st century, with potential effects on terrestrial ecosystems, including the Greenland ice sheet (GrIS). This study considers the impacts of elevated nitrate concentrations on the abundance and composition of bulk and active prokaryotic communities sampled from in situ nitrate fertilization plots on the GrIS surface. Nitrate concentrations were successfully elevated within ice holes (cryoconite holes), however nitrate additions applied to surface ice did not persist, therefore associated community changes were not investigated. Bulk and active cryoconite community cell abundance was unaltered by nitrate additions when compared to control holes using a quantitative PCR approach, and nitrate was found to have minimal affects on the 16S rRNA gene-based community composition. Together, these results indicate that sampled cryoconite communities were not nitrate limited. Instead, temporal changes in biomass and community composition were more pronounced. As these in situ incubations were short (6 weeks), and the community composition across GrIS surface ice is highly variable, we suggest that further efforts should be considered to investigate the potential long-term and biogeographical impacts of increased nitrate across the GrIS. In addition, further methodological approaches should be tested to facilitate investigations of surface ice communities. |