Title: “Geomicrobiology in and beneath polar ice sheets”
Abstract: Few data exist on particulate and dissolved organic matter in and beneath polar ice. When collected in concert with other impurities in the ice, such data can provide new and corroborative information regarding atmospheric circulation, climate change, sea-ice extent, and biomass burning. Once thought devoid of life, glacial ice is now recognized as a habitat for life and a potentially significant global reservoir of organic carbon. Biological data can also be used to more accurately interpret paradoxes that exist in the concentrations and isotopic ratios of biologically important gases in ice cores. An understanding of the density and physiological state of ice-bound microbes may help interpret the paleo-record in past and future ice cores. Biological matter deposited on the surface of glaciers and ice sheets also represent seed material for subglacial environments. Subglacial environments represent a crucial and relatively unstudied transition zone between an ice sheet and underlying geologic substrata. Processes taking place in this zone determine the: (i) rate of ice flux through an ice sheet, (ii) erosional and sedimentary dynamics of an ice sheet, (iii) phylogenetic and metabolic diversity, (iv) biogeochemical transformation of materials between an ice sheet and its geologic substrate, and (v) transport of nutrients to the surrounding marine environment. The first indirect evidence for life in subglacial lakes came from studies of accretion ice overlying Vostok Subglacial Lake, one of the largest lakes on our planet. Direct sampling of Whillans Subglacial Lake in January 2013 and Mercer Subglacial Lake in January 2019 provided the first unequivocal evidence for thriving microbial ecosystems beneath the West Antarctic Ice Sheet. Results from these subglacial studies showed that this ecosystem is fueled by relict marine organic matter and in situ chemolithoautotrophic carbon production. I will present a short history of geobiological research on polar ice sheets, present data on the bacterial distribution in the West Antarctic Ice Sheet from the Late Glacial Maximum to the early Holocene, microbial changes in Himalayan Glaciers over the past 60 years, and discuss recent biogeophysical discoveries in the subglacial aquatic environment beneath the Greenland and West Antarctic ice sheets.
Short Bio: John Priscu is a Regents Professor of Ecology and co-director of the Subzero Research Facility at Montana State University, Bozeman. He has spent 35 field seasons in Antarctica conducting research on life under ice-shelves, the Southern Ocean, sea ice, permanently ice covered lakes, life beneath the Antarctic ice sheet, and chaired SCAR’s international subglacial group of experts. Priscu has been a principal investigator on the NSF-funded McMurdo LTER project since 1993 where his research focuses on biogeochemistry of the permanently ice-covered lakes in the McMurdo Dry Valleys. He was lead author of the first manuscripts to describe life in Antarctic lake ice and life in Subglacial Lake Vostok and has contributed to other seminal papers on the geomicrobiology of solid ice and subglacial environments. Priscu was Chief Scientist of the WISSARD expedition that retrieved the first samples from beneath the West Antarctic Ice Sheet proving that functional subglacial ecosystems exist. He is now the Chief Scientist of the SALSA project, which drilled through 1100m of ice in January 2019 to sample Mercer Subglacial Lake. Priscu has taken more than 200 undergraduate, graduate and postgraduate students to Antarctica and the arctic as part of his research efforts during this period. His work also focuses on microbial life in Himalayan glaciers and the study of life on icy worlds beyond Earth putting him in Tibet, Alaska and Greenland as an investigator on various Chinese and NASA projects. He is a Fellow of the American Society of Limnology and Oceanography, American Association for the Advancement of Science, and the American Geophysical Union, is a Humboldt Scholar, and has received numerous awards for his research, including a valley and a stream in Antarctica named in his honor, the Goldwaithe Medal in Glaciology for his work on polar ice sheets, the International Medal for Scientific Excellence from the Scientific Committee on Antarctic Research, and the E.O. Wilson Biodiversity Award for his work on microbial dynamics in polar lakes. Priscu has published more than 250 scholarly articles on his research and edited 4 books. More details can be found at: http://www.montana.edu/priscu/ and https://salsa-antarctica.org/