Lake Vanda: A sentinel for climate change in the McMurdo Sou

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TitleLake Vanda: A sentinel for climate change in the McMurdo Sound Region of AntarcticaAbstractLake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by >50 percent, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 deg C and the bottom-most waters by at > 4 deg C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today. Copyright 2016 Elsevier B.V.AcknowledgementsWe would like to thank the many colleagues with whom we have worked over the years whose multiple insights and hard work have led to most of the ideas expressed here. In particular, we thank all members of the MCM-LTER and the New Zealand field teams who have maintained exceptional records from the Wright Valley over the years. Specifically, we thank Hilary Dugan, John Priscu, Amy Chiuchiolo, Tyler Mackey and Dawn Sumner for sharing their data and expertise. In addition, we are grateful to the constructive feedback provided by an anonymous reviewer which significantly improved the manuscript. Field support has been from the US Antarctic Program and Antarctica New Zealand. Funding for this work has been provided by the US Antarctic Program, the McMurdo LTER (National Science Foundation PLR grant 1115245), Antarctica New Zealand, the New Zealand Ministry for Research, Science and Technology, the New Zealand Antarctic Research Institute, and the Research Foundation of the State University of New York at Oneonta.Funding DetailsAntarctica New Zealand; 1115245, NSF, National Science Foundation; SUNY, State University of New York

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1st AuthorCastendyk, D.AuthorCastendyk, D.Obryk, M.Leidman, S.Gooseff, M.Hawes, I.Year2016JournalGlobal and Planetary ChangeVolume144Pages213-227DOI10.1016/j.gloplacha.2016.06.007URLhttps://www.scopus.com/inward/recor.....281c1c7fa7805fb0be195c21dKeywordsrank5

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TypeArticleCitationCastendyk, D., Obryk, M., Leidman, S., Gooseff, M. and Hawes, I. (2016). Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica. Global and Planetary Change, 144: 213-227 IdentifierCastendyk2016Relevancerank5

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Hawes, I.