Diversity and potential sources of microbiota associated with snow on western portions of the Greenland Ice Sheet

Abstract

Snow overlays the majority of the Greenland Ice Sheet (GrIS). However, there is very little information available on the microbiological assemblages that are associated with this vast and climate-sensitive landscape. In this study, the structure and diversity of snow microbial assemblages from two regions of the western GrIS ice margin were investigated through the sequencing of small subunit ribosomal RNA genes. The origins of the microbiota were investigated by examining correlations to molecular data obtained from marine, soil, freshwater and atmospheric environments and geochemical analytes measured in the snow. Snow was found to contain a diverse assemblage of bacteria (Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria) and eukarya (Alveolata, Fungi, Stramenopiles and Chloroplastida). Phylotypes related to archaeal Thaumarchaeota and Euryarchaeota phyla were also identified. The snow microbial assemblages were more similar to communities characterized in soil than to those documented in marine ecosystems. Despite this, the chemical composition of snow samples was consistent with a marine contribution, and strong correlations existed between bacterial beta diversity and the concentration of Na(+) and Cl(-) . These results suggest that surface snow from western regions of Greenland contains exogenous microbiota that were likely aerosolized from more distant soil sources, transported in the atmosphere and co-precipitated with the snow.

Microbiology: lessons from a first attempt at Lake Ellsworth

“…Some of the fundamental questions in microbiology that still remain and need to be properly addressed in developing deep subglacial lake access technology. have been reported in the snow and ice from the Antarctic (table 1; see also table 2 in Pearce [34]), following similar studies in other regions in the cryosphere, including snow from the Alps [35], the Tibetan plateau [36], Arctic Svalbard [37,38], Arctic Greenland [39], Arctic Alaska [40] and Antarctic snow (this study, [41]). Microbial communities differ significantly across the environments of nthe cryosphere [42], and this also applies to Antarctica, including both supraglacial lakes [43] and subglacial lakes, with Ellsworth potentially harbouring unique microbial communities.…”

Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier

“…Microbial communities living in snow may originate from more distant soils, aerosolized and deposited with snow (Cameron et al, 2015). We therefore considered this habitat as an exogenous source of microbial pioneers.…”

Diversity and abundance of microbial eukaryotes in stream sediments from Svalbard

“…Unlike the other sediment samples from Svalbard, but similar to the snow sample from Robertson Glacier, sample M also contains no Ciliophora. The most abundant phylum in sample M was Basidiomycota (79%) and snow samples from Thule, Greenland and near the North Pole also contained high relative abundances (>50%) of Fungi (Bachy et al 2011;Cameron et al 2015). It should be noted that the microbial eukaryal community composition of snow samples is highly variable (Hamilton et al 2013;Cameron et al 2015) and is dependent on local terrestrial (soil) sources (Cameron et al 2015) and marine microbial aerosols (Harding et al 2011).…”

“…However, there have been comparatively fewer studies conducted on microbial eukaryotes in cold, highlatitude ecosystems despite the potentially important role that they have in nutrient cycling in these environments. The few cold high-latitude terrestrial ecosystems where microbial eukaryotes have been investigated (Table 1) have focussed on their diversity in glacial cryoconite habitats (Christner et al 2003;Cameron et al 2012;Hamilton et al 2013), freshwater cyanobacterial mats (Jungblut et al 2012) permafrost soils (Coolen et al 2011;Mackelprang et al 2011;Tveit et al 2013Tveit et al , 2014Geisen et al 2015), snow (Harding et al 2011;Hamilton et al 2013;Cameron et al 2015), streams and porewaters (Luo et al 2009;Crump et al 2012), and subglacial environments (Hamilton et al 2013). One of the most abundant phyla found in highlatitude environments are Ciliophora (Tveit et al 2013;Geisen et al 2015) and their presence may control the abundance of bacteria and recycling of soil organic matter (Coolen et al 2011).…”