Microbial Communities in Sediments From Different Landform Systems, Svalbard

Svalbard is host to a range of glacier types with different thermal regimes, behaviors and complex hydrological networks and landforms. Here, we hypothesize that the (H1) surge-type glaciers will host different microbial community structures, and that (H2) different landform types will also host different microbial community structures. We further hypothesize that (H3) these differences in microbial communities will result in different concentrations and compositions of extracellular polymeric substances (EPS) in response to potentially different stressors associated with surging behavior (H4) or the formation of different landforms. To test these hypotheses, supra- and subglacial sediments from different glacier types and landforms in southwest and west Spitsbergen were collected (26 locations, across 10 glaciers). 16S rRNA gene amplicon sequencing and epifluorescence microscopy was used to determine the microbial community composition, diversity and biomass. At the sequence level all samples were predominantly different across all glaciers and landforms with only 72/1,268 sequences detected in two or more samples. Diversity indices showed samples generally have similar levels of diversity despite these differences in community structure. The EPS concentrations were also similar (0.34 ± 0.71 mg g−1) at all locations excluding a single outlier, suggesting consistent production of EPS. This has implications for understanding the microbial ecosystem response to changing glacial dynamics as the extent and thermal regimes of glaciers shift due to climate change.