University of Otago Geology Seminar

The response of the Antarctic ice sheets to global warming is an existential challenge. While past records show that melting from warming waters beneath the ice sheets can be quantified, recent research reveals that the East Antarctic Ice Sheet is susceptible to melting from atmospheric warming, a mechanism that is not well constrained by paleoclimate data. However, the information preserved within permafrost and glacial geomorphology has the potential to reveal greater detail of past terrestrial climate, landscape evolution and environmental factors. Surface exposure dating, and depth profiles of in-situ cosmogenic ¹⁰Be and ²⁶Al, coupled with 16S rRNA amplicon sequencing reveals that surface soil and subsurface permafrost from lower Wright Valley (7,000 – 25,000-year-old) and Pearse Valley (>180,000-year-old) have distinct differences in their microbial communities, indicating different environmental conditions. The study shows that surface sediments and subsurface permafrost can provide a temporally constrained record of environmental conditions and subsequently Antarctic ice sheet fluctuation. The integrated approach applied here can be extended to other permafrost occurrences and regions to expand our understanding of past environmental changes in Antarctica and other regions. In contrast, at high elevation sites (>1000 masl), the cosmogenic nuclide measurements at Table Mountain are best interpreted as erosion rates, and at the Friis Hills, DNA was beyond detection limits. The inability to identify DNA using amplicon sequencing in the Friis Hills is consistent with previous efforts to analyse high elevation soils and permafrost using 16S rRNA gene amplification sequencing, suggesting microbial habitability is severely restricted in persistent cold, arid habitats. 

This talk will take place in person in the Benson Common Room (Gn9, Geology Building) AND will be available live on Zoom at the following link: https://bit.ly/otagogeology.

Contact: otago@gsnz.org.nz