Large cryoconite aggregates on a Svalbard glacier support a diverse microbial community including ammonia-oxidizing archaea

Abstract

The aggregation of surface debris particles on melting glaciers into larger units (cryoconite) provides 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 (of surface debris, ice and meltwater), quantitative polymerase chain reactions (targeting the 16S ribosomal ribonucleic acid and amoA genes), pyrosequencing and multivariate statistical analysis to suggest possible factors driving the ecology of prokaryotic microbes on the surface of Aldegondabreen and their potential role in nitrogen cycling. The combination of high nutrient input with subsidy from the bird colonies, supraglacial meltwater flow and the presence of fine, clay-like particles supports the formation of centimetre-scale 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 well-known in supraglacial environments. Importantly, ammonia-oxidizing archaea were detected in the aggregates for the first time on an Arctic glacier.

Microbial community changes along the Ecology Glacier ablation zone (King George Island, Antarctica)

“…Chlorophyll a content, DOC, inorganic nitrogen compounds, and reactive phosphorus concentrations were in line with published values for Antarctic and high Arctic glaciers (Porazinska et al 2004;Foreman et al 2007;Telling et al 2012;Zarsky et al 2013). Anion and cation concentrations were at the same level or slightly lower than those published for Antarctic glaciers, with the exception of Mg 2?…”

“…The gradually exposed ice is subjected to wind, solar radiation, and aeolian inputs of mineral and organic materials, resulting in its melting; the water produced circulates over and in the ice structure (Hodson et al 2008). This water often carries a suspension that originates from wind-carried debris from local and from more distant sources (Zarsky et al 2013). The dark dust deposit is known as cryoconite, and in sufficient quantities reduces ice surface albedo and accelerates melting.…”

A spatial investigation of the environmental controls over cryoconite aggregation on Longyearbreen glacier, Svalbard

“…These findings have important implications for the distribution of aeolian debris and microorganisms and their residence time upon the ice, both of which exert a crucial control over albedo (Bøggild et al, 2010;Yallop et al, 2012). Thus, photoautotrophy and the interaction of microorganisms with atmospheric impurities clearly make a significant contribution towards supraglacial melt, forming stable aggregates within which niche communities and microenvironments can develop (Edwards et al, 2013;Zarsky et al, 2013), certainly feeding into, and contributing to the ecology of, both proglacial and fjord environments.…”

“…Cryoconite material sits upon and within a dynamic supraglacial weathering crust environment (Müller and Keeler, 1969), within which physical and hydrological influences act upon it, in addition to biogeochemical interactions. Radionuclide analysis (Tieber et al, 2009) and timelapse imagery (Irvine-Fynn et al, 2011) both suggest that, despite seasonal meltwater flow, cryoconite can reside on the ice surface for extended time periods, up to decades, thereby creating complex microbial community structures and promoting the development of niche communities and microenvironments (Edwards et al, 2013;Zarsky et al, 2013).…”

“…Given the variability of cryoconite microstructure between Arctic glaciers , and the development of niche communities and microenvironments (Edwards et al, 2013;Zarsky et al, 2013), even on adjacent glaciers, care must be taken as to the wider representativeness of the data analysed and discussed henceforth. This research employs a spectrophotometric approach, using 96-well plates and performing a variety of assays, to allow rapid, glacierwide determination of specific biochemical parameters -in !…”