Aldegondabreen cryoconite Targeted Locus

The aggregation of surface debris (cryoconite) on melting glaciers into larger may provide microenvironments for various microorganisms and metabolic processes. Here we investigate the microbial community on the surface of Aldegondabreen, a valley glacier in Svalbard which is supplied with carbon and nutrients from different sources across its surface, including colonies of seabirds. We used a combination of geochemical analysis (surface debris, ice and meltwater), quantitative PCR (targeting the 16S rRNA and amoA genes), pyrosequencing and multivariate statistical analysis to better understand the ecology of prokaryotic microbes on the surface on Aldegondabreen and their role in nitrogen cycling. The combination of high nutrient input, supraglacial melt water flow and the presence of fine, claylike particles supports the formation of cmscale cryoconite aggregates in some areas of the glacier surface. We show that a diverse microbial community is present, dominated by the cyanobacteria, Proteobacteria, Bacteroidetes, and Actinobacteria, that are wellknown in supraglacial environments. Allochthonous material including plant tissuederived chloroplasts was also identified in the molecular analysis. Importantly, ammonia oxidizing archaea (AOA) were detected in the aggregates for the first time on an Arctic glacier.