Rapid development of anoxic niches in supraglacial ecosystems

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Ewa A. Poniecka, Elizabeth A. Bagshaw, Martyn Tranter, Henrik Sass, Christopher J. Williamson, Alexandre M. Anesio, Black and Bloom Team
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2018
• Subjects: cryoconite hole; anoxic niches; greenland; microbiology; microsensors; envir; geo; Greenland; Antarctic and Alpine Research; Arctic; Ice Sheet
• Online Access: https://doi.org/10.1080/15230430.2017.1420859; https://doaj.org/article/603265b68da74e2e97f14151614ab596

Microorganisms play a significant role in changing the physical properties of the surface of the Greenland Ice Sheet. Cryoconite holes are a hotspot for this microbial activity, yet little is known about the REDOX conditions that develop within them. In this study, we used oxygen microelectrodes and microoptodes to measure for anoxic conditions at the microscale, for the first time revealing a potential niche for anaerobic microorganisms and anaerobic processes. The development of an anoxic zone 2 mm deep within a 6 mm-thick layer of cryoconite sediment was observed within an hour of disturbance, showing rapid acclimation to changing physical conditions. Long-term (half year) incubations of cryoconite material showed a peak of oxygen production and consumption after forty days and reached a low-activity, steady state by day 116, with a persisting anoxic zone beginning between 2 mm and 4 mm deep. Anaerobic microorganisms, which have received little attention to date, should therefore be considered an important component of the cryoconite ecosystem. We discuss the possible dynamics of oxygen concentrations in the supraglacial system and infer that anoxic zones are an important factor in the development of cryoconite sediment communities.