Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene

Abstract

We present the first long-term, highly resolved prokaryotic cell concentration record obtained from a polar ice core. This record, obtained from the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core, spanned from the Last Glacial Maximum (LGM) to the early Holocene (EH) and showed distinct fluctuations in prokaryotic cell concentration coincident with major climatic states. The time series also revealed a ~1,500-year periodicity with greater amplitude during the Last Deglaciation (LDG). Higher prokaryotic cell concentration and lower variability occurred during the LGM and EH than during the LDG. A sevenfold decrease in prokaryotic cell concentration coincided with the LGM/LDG transition and the global 19 ka meltwater pulse. Statistical models revealed significant relationships between the prokaryotic cell record and tracers of both marine (sea-salt sodium [ssNa]) and burning emissions (black carbon [BC]). Collectively, these models, together with visual observations and methanosulfidic acid (MSA) measurements, indicated that the temporal variability in concentration of airborne prokaryotic cells reflected changes in marine/sea-ice regional environments of the WAIS. Our data revealed that variations in source and transport were the most likely processes producing the significant temporal variations in WD prokaryotic cell concentrations. This record provided strong evidence that airborne prokaryotic cell deposition differed during the LGM, LDG, and EH, and that these changes in cell densities could be explained by different environmental conditions during each of these climatic periods. Our observations provide the first ice-core time series evidence for a prokaryotic response to long-term climatic and environmental processes.

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

“…2D). High-latitude open water and sea ice are rich in microbial communities, components of which may be collected by passing storms and delivered onto the ice sheet (e.g., prokaryotes, DNA), offering insights into offshore environmental processes (51,52). To investigate environmental changes prior to and after the ice sheet reconfiguration recorded in the Patriot Hills BIA, we applied an established ancient DNA methodology and sequencing to provide a description of ancient microbial species preserved within the ice (Methods).…”

WATSON:In SituOrganic Detection in Subsurface Ice Using Deep-UV Fluorescence Spectroscopy

“…Bulk measurements of cell levels have previously been obtained in natural glacial ice systems and were determined to be between 10 2 and 10 8 cells/mL (Mader et al, 2006;Miteva et al, 2009;Santibáñez et al, 2018). However, what is unaccounted for in these measurements is the submillimeterto centimeter-scale spatial heterogeneity in the distribution of cells within the ice.…”

“…O nce considered inhospitable to life, in recent decades icy environments on Earth have been found that preserve organic material and even harbor active microbial communities (Priscu et al, 1998(Priscu et al, , 1999Siegert et al, 2001;Priscu, 2005;Santibáñez et al, 2005Santibáñez et al, , 2018Krembs et al, 2011;Uhlig et al, 2015). Glacial ice on Earth is known to contain organic material (Barnes et al, 2003;Barletta et al, 2012), including bacteria, algae, viruses, plant fragments, pollen grains, and black carbon.…”

Biogeochemical Connectivity Between Freshwater Ecosystems beneath the West Antarctic Ice Sheet and the Sub‐Ice Marine Environment

“…Riverine fluxes have long been recognized as an important source of carbon and nutrients to the oceans (Meybeck, 1982), with high fluxes of dissolved organic carbon (DOC) occurring at low latitudes (0-30°; 62% of total known global inputs) and northern high latitudes (60-90°; 19%) (Dai et al, 2012). Polar ice sheets and glaciers, which store~70% of the Earth's fresh water have only recently been identified as important repositories of organic matter (Hood et al, 2015;Lawson et al, 2014;Santibáñez et al, 2018) and biologically important nutrients (Bhatia et al, 2013;Dubnick et al, 2017;Hawkings et al, 2016;Wadham et al, 2016) that can be exported to marine environments. The Greenland Ice Sheet is thought to dominate the fluxes from large ice sheets due to its high rate of glacier mass turnover via surface (supraglacial) melt and iceberg calving (Hood et al, 2015); however, the absence of data from the Antarctic ice sheet (AIS) has prevented meaningful comparison between the worlds' major ice sheets.…”