Recent rapid salinity rise in three East Antarctic lakes

• Published in: Journal of Paleolimnology
• Main Authors: Hodgson, Dominic A., Roberts, Donna, McMinn, Andrew, Verleyen, Elie, Terry, Bruce, Corbett, Christine, Vyverman, Wim
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 2006
• Subjects: Ecology and Environment; Antarctic; East Antarctica; Law Dome; Windmill Islands; Antarc*; Antarctica; ice core; Ice Sheet; Sea ice
• Online Access: http://nora.nerc.ac.uk/id/eprint/945/; https://doi.org/10.1007/s10933-006-9010-0

Research in East Antarctica has shown several recent environmental changes that may be linked to human impacts on climate. In order to detect the influence and context of these changes on coastal aquatic ecosystems we examined lake sediment cores from three lakes in the Windmill Islands, East Antarctica; Beall Lake, Holl Lake and ȁ8Lake Mȁ9. Cores were sectioned at␣2.5 mm intervals. Their diatom species composition was examined to detect changes in lake salinity using a diatom-salinity transfer function, and their algal pigment content was examined to detect photoautotrophic community responses to environmental change. Results showed that Holl Lake originated in a depression exposed by Holocene recession of the continental ice sheet and that Beall Lake and Lake M originated as isolated marine basins formed by changes in relative sea level. A general late Holocene trend of declining lake salinity was evident in all three lakes, interrupted by one short-term high salinity event in Beall Lake. This is consistent with a long-term positive moisture balance. This general decline in salinity has been followed by a remarkable recent rapid increase in salinity in all three lakes in the last few decades. We speculate that this rapid increase in salinity might be linked to changes taking place in the region including feedbacks resulting from decreasing sea ice extent as recorded in the nearby Law Dome ice core, and positive feedbacks in the catchments whereby reduced snow cover has led to decreased albedo, which in turn has caused increased evaporation and sublimation. Collectively these changes have shifted the lakes across a threshold from positive to negative moisture balance. A minor, but not rapid shift in the abundance of diatom pigments relative to pigments from green algae and cyanobacteria was also detected suggesting that some changes in photoautotrophic community composition have occurred. Measurements of modern nutrient levels are also higher than would be expected in Beall Lake and Holl Lake, given the ...