Impact of Lake-Level and Climate Changes on Microbial Communities in a Terrestrial Permafrost Sequence of the El'gygytgyn Crater, Far East Russian Arctic

Abstract

Microbial permafrost communities play an important role in carbon cycling and greenhouse gas fluxes. Despite the importance of these processes, there is a lack of knowledge about how environmental and climatic changes affect the abundance and composition of microorganisms. Here, we investigated the changing distribution of permafrost microorganisms in response to climate and lake-level changes. The permafrost core was drilled at the near shore of Lake El'gygytgyn, Far East Russian Arctic, and a combined microbiological and lipid biomarker approach was applied. The lower part of the permafrost core, deposited under subaquatic conditions, contains only small amounts of microbial signals; total organic carbon (TOC) content is sparse. After exposure of the site to subaerial conditions during the Allerød, the abundance of Bacteria and Archaea started to increase and the lake-level change is especially evidenced by the relative proportion of archaeal biomarkers. This increase is supported by rising bacterial and archaeal 16S ribosomal ribonucleic acid (rRNA) gene copy numbers and significant amounts of TOC during the late Allerød. After a small decrease during the colder Younger Dryas, the TOC content and the microbial signals strongly increase during the Holocene, presumably stimulated by pedogenesis. The occurrence of intact phospholipids indicates the presence of living microorganisms in these deposits. Our data suggest that methane formation is mainly expected for the subaerial interval, especially the Holocene where methanogens were identified by fingerprinting. This study emphasises the role of the uppermost permafrost deposits as a hotspot of carbon cycling in arctic environments, especially in the light of expected future global warming.

Microbial Signatures in Deep CO2-Saturated Miocene Sediments of the Active Hartoušov Mofette System (NW Czech Republic)

“…(A) Stratigraphical and lithological description, (B) the hopanoid distribution and its relative abundance (%), (C) δ 13 C hopanoids of different hopanoids, and (D) the (core) GDGT distribution and its relative abundance. Dirghangi et al, 2013;Bischoff et al, 2014;Naeher et al, 2014;Schubotz et al, 2018;Bale et al, 2019;Evans et al, 2019). Both GDGT types occurred across the whole lithological profile with isoGDGT-0, isoGDGT-1, brGDGT-I, brGDGT-II, and brGDGT-III being the most prominent ( Figure 3D).…”

Substrate potential of last interglacial to Holocene permafrost organic matter for future microbial greenhouse gas production

“…Approximately 30-50 g of the freeze-dried and ground samples was extracted using a flow blending system modified after Bligh and Dyer (1959) as described in Stapel et al (2016). Subsequently, the obtained sediment extract was separated into four different fractions of increasing polarity (low polar lipids, free fatty acids, glycolipids, and polar lipids) following a method described by Zink and Mangelsdorf (2004).…”

Microbial abundance in lacustrine sediments: a case study from Lake Van, Turkey

“…Other microbiological studies from ICDP projects that recovered deep sediments either did not perform cell counts (e.g. El'Gygytgyn Crater, (Brigham-Grette et al 2013;Bischoff et al 2014) or the sediments were deposited under very special conditions, e.g. as post-impact sediments in the Chesapeake Bay (Gohn et al 2008;Cockell et al 2012), and therefore exhibit rather peculiar cell count profiles.…”