Summer-winter transitions in Antarctic ponds I: The physical
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TitleSummer-winter transitions in Antarctic ponds I: The physical environmentAbstractAbstract Meltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to >80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3-5 to >60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0-15% of the volume of each pond was still liquid, although this represented 5-35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period. Copyright Antarctic Science Ltd 2011.AcknowledgementsThis research was funded by the New Zealand Foundation for Research, Science and Technology (Contracts C01X0708 and C01X0306) to the National Institute of Water and Atmospheric Research (NIWA). Antarctica New Zealand provided logistic support, in collaboration with the US National Science Foundation. Nat Wilson was an integral part of the field team. We are grateful to NIWA Christchurch for laboratory, technical and infrastructural support, particularly to Dr Clive Howard-Williams, and to two anonymous reviewers for critical comments on the manuscript
TypeArticleCitationHawes, I., Safi, K., Sorrell, B., Webster-Brown, J. and Arscott, D. (2011). Summer-winter transitions in Antarctic ponds I: The physical environment. Antarctic Science, 23(3): 235-242 IdentifierHawes2011aRelevancerank5
