Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes
The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite...
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ftportlandstate:oai:pdxscholar.library.pdx.edu:geology_fac-1071 2023-05-15T13:58:45+02:00 Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes Telling, Jon Anesio, Alexandre M. Tranter, Martyn Fountain, Andrew G. Nylen, Thomas H. Hawkings, Jon Singh, Virendra B. Kaur, Preeti Musilova, Michaela Wadham, Jemma L. 2014-12-01T08:00:00Z application/pdf https://pdxscholar.library.pdx.edu/geology_fac/72 https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1071&context=geology_fac unknown PDXScholar https://pdxscholar.library.pdx.edu/geology_fac/72 https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1071&context=geology_fac Geology Faculty Publications and Presentations McMurdo Dry Valleys (Antarctica) Cryoconite Antarctica -- Ecology Photosynthesis Microbial ecology--Antarctica Geology Glaciology Microbiology text 2014 ftportlandstate 2022-01-09T19:33:09Z The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones. Text Antarc* Antarctic Antarctica Canada Glacier glacier* McMurdo Dry Valleys polar desert Portland State University: PDXScholar Antarctic Austral Canada Canada Glacier ENVELOPE(162.983,162.983,-77.617,-77.617) McMurdo Dry Valleys |
institution |
Open Polar |
collection |
Portland State University: PDXScholar |
op_collection_id |
ftportlandstate |
language |
unknown |
topic |
McMurdo Dry Valleys (Antarctica) Cryoconite Antarctica -- Ecology Photosynthesis Microbial ecology--Antarctica Geology Glaciology Microbiology |
spellingShingle |
McMurdo Dry Valleys (Antarctica) Cryoconite Antarctica -- Ecology Photosynthesis Microbial ecology--Antarctica Geology Glaciology Microbiology Telling, Jon Anesio, Alexandre M. Tranter, Martyn Fountain, Andrew G. Nylen, Thomas H. Hawkings, Jon Singh, Virendra B. Kaur, Preeti Musilova, Michaela Wadham, Jemma L. Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
topic_facet |
McMurdo Dry Valleys (Antarctica) Cryoconite Antarctica -- Ecology Photosynthesis Microbial ecology--Antarctica Geology Glaciology Microbiology |
description |
The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones. |
format |
Text |
author |
Telling, Jon Anesio, Alexandre M. Tranter, Martyn Fountain, Andrew G. Nylen, Thomas H. Hawkings, Jon Singh, Virendra B. Kaur, Preeti Musilova, Michaela Wadham, Jemma L. |
author_facet |
Telling, Jon Anesio, Alexandre M. Tranter, Martyn Fountain, Andrew G. Nylen, Thomas H. Hawkings, Jon Singh, Virendra B. Kaur, Preeti Musilova, Michaela Wadham, Jemma L. |
author_sort |
Telling, Jon |
title |
Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
title_short |
Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
title_full |
Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
title_fullStr |
Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
title_full_unstemmed |
Spring Thaw Ionic Pulses Boost Nutrient Availability and Microbial Growth in Entombed Antarctic Dry Valley Cryoconite Holes |
title_sort |
spring thaw ionic pulses boost nutrient availability and microbial growth in entombed antarctic dry valley cryoconite holes |
publisher |
PDXScholar |
publishDate |
2014 |
url |
https://pdxscholar.library.pdx.edu/geology_fac/72 https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1071&context=geology_fac |
long_lat |
ENVELOPE(162.983,162.983,-77.617,-77.617) |
geographic |
Antarctic Austral Canada Canada Glacier McMurdo Dry Valleys |
geographic_facet |
Antarctic Austral Canada Canada Glacier McMurdo Dry Valleys |
genre |
Antarc* Antarctic Antarctica Canada Glacier glacier* McMurdo Dry Valleys polar desert |
genre_facet |
Antarc* Antarctic Antarctica Canada Glacier glacier* McMurdo Dry Valleys polar desert |
op_source |
Geology Faculty Publications and Presentations |
op_relation |
https://pdxscholar.library.pdx.edu/geology_fac/72 https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1071&context=geology_fac |
_version_ |
1766267083848417280 |