Patterns in Microbial Assemblages Exported From the Meltwater of Arctic and Sub-Arctic Glaciers

Abstract

Frontiers in Microbiology | www.frontiersin.org April 2020 | Volume 11 | Article 669 Kohler et al.(Sub)Arctic Glacier-Exported Microbial Assemblages differences in dominant hydrological flowpaths, OTUs can also serve as indicators for more localized microbially mediated processes not captured by the traditional characterization of bulk meltwater hydrochemistry. These results collectively promote a better understanding of microbial distributions across the Arctic, as well as linkages between the terrestrial cryosphere habitats and downstream ecosystems.

Meltwater runoff from the Greenland Ice Sheet reveals microbial consortia from contrasting subglacial drainage systems

“…Composition of exported communities during the 2015 melt-345 season also reflects that of a previous study in the region(Cameron et al, 2017), but also in 346 glacial systems elsewhere(Kohler et al, 2020), and strengthens the view of major phylotypes 347 characterising the subglacial margin of glaciers worldwide. For example, the dominance of 348Betaproteobacteria has previously been proposed to be a main constituent of subglacial 349 communities(Boetius et al, 2015, Kohler et al, 2020, and Betaproteobacteria account for the 350 majority of exported populations at LG (most Betaproteobacteria sequences fall within the 351 order Burkholderiales at LG). The same is true for other major LG orders (Xanthomonadales, 352Sphingobacteriales, Micrococcales, etc.…”

“…a sustained core microbiome throughout the melt season at LG aligns with 343 an increasing number of studies of proglacial meltwater systems(Dieser et al, 2014, Sheik et 344 al., 2015, Kohler et al, 2020. Composition of exported communities during the 2015 melt-345 season also reflects that of a previous study in the region(Cameron et al, 2017), but also in 346 glacial systems elsewhere(Kohler et al, 2020), and strengthens the view of major phylotypes 347 characterising the subglacial margin of glaciers worldwide.…”

“…The same is true for other major LG orders (Xanthomonadales, 352Sphingobacteriales, Micrococcales, etc. ), which have also been shown to dominate previously 353 monitored proglacial rivers(Kohler et al, 2020).354 355 Whether this conserved microbiome is representative of a relatively homogeneous, 'blanket' 356 ecosystem beneath the ice, however, is difficult to reconcile from proglacial communities alone. 357 The persistence of a core microbiota throughout the melt season (i.e.…”

“…The very low abundance of 502 methanogens in SLW despite the high methane concentrations in sediments also resembles 503 descriptions here. Some of the information obtained at LG can therefore likely be extended to 504 a more general view of ice-sheet beds, further highlighting similarities between glacial 505 environments worldwide(Kohler et al, 2020), even under contrasting hydrological regimes. 506Still, a full picture of subglacial ecosystems may ultimately only be depicted via direct access to 507 the subsurface through drilling operations, or potentially via more extensive sampling and 508 sequencing efforts.509 510 research was also part of the UK NERC funded DELVE programme (NERC grant 515 NE/I008845/1 to J.L.W.).…”

Glacial microbiota are hydrologically connected and temporally variable

“…Vavrus et al ., 2009; Bintanja and Andry, 2017; Södergren et al ., 2017; Overland et al ., 2019), which may impact the form and function of in situ biological communities. Glacial meltwater exports microbial assemblages (Dubnick et al ., 2017; Cameron et al ., 2017b; Kohler et al ., 2020), sediments (Hudson et al ., 2014; Overeem et al ., 2017) and nutrients (Hawkings et al ., 2015) from glaciers to downstream environments where they have ecological impacts, such as seeding new ecosystems (e.g. Rime et al ., 2016) and fertilizing coastal productivity (e.g.…”