Physical Limnology of the Mcmurdo Dry Valleys Lakes
- John C. Priscu
Published Online: 16 MAR 2013
Copyright 1998 by the American Geophysical Union.
Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica
How to Cite
Spigel, R. H. and Priscu, J. C. (1998) Physical Limnology of the Mcmurdo Dry Valleys Lakes, in Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica (ed J. C. Priscu), American Geophysical Union, Washington, D. C.. doi: 10.1029/AR072p0153
- Published Online: 16 MAR 2013
- Published Print: 28 JAN 1998
Print ISBN: 9780875908991
Online ISBN: 9781118668313
- Desert ecology—Antarctica—McMurdo Dry Valleys
We present high-resolution measurements of conductivity and temperature made from January 1990 to December 1993 in the east and west lobes of Lake Bonney and in Lakes Vanda, Hoare, Fryxell, Joyce, and Miers. These measurements were used to calculate profiles of density and stability, and thereby infer mechanisms and strengths of mixing in the water columns of the lakes. Transects along the length of Lake Bonney allowed estimates of horizontal exchanges in and between the two lobes of that lake and help to explain some of the characteristics of single profiles measured in other lakes. Stratification in all the lakes is controlled mainly by concentration of dissolved solids (“salinity”), with temperature exerting such a minor influence as to act virtually as a passive tracer. An exception is in the upper two-thirds of Lake Vanda and at the bottom of Lake Miers, where solar heating in the presence of weak salinity gradients gives rise to thermohaline convection. The distinctive and relatively invariant shapes of the density profiles in the different lakes is due to distinctive distributions of salts in the water columns of these lakes, distributions that can only be explained in terms of geochemical processes acting over time scales much longer than the annual overturning cycle that dominates patterns of stratification and mixing in temperate, freshwater lakes. Temperatures in the McMurdo Dry Valleys lakes, in contrast to salinities, do respond to changes in weather, climate, and water levels on a seasonal and annual basis, although to a much smaller extent than in temperate lakes. Stability reaches extremely high levels in the chemoclines of the two lobes of Lake Bonney, being slightly lower in the bottom waters of Lake Vanda. Stabilities in Lakes Fryxell and Joyce, although still very high in comparison with freshwater lakes, are much lower than in Bonney and Vanda. Maximum stabilities in Lakes Hoare and Miers are similar to those found in the summer thermoclines of freshwater lakes. With the exception of thermohaline convection cells in Lake Vanda and Lake Miers, our measurements do not support the presence of turbulent diffusion in the main bodies of the lakes; however, profiles did document mechanically generated turbulence just below the ice in Lake Miers (probably associated with the meltwater stream through-flow in that lake, the only lake with a stream outlet) and much weaker turbulence in the narrows connecting the two lobes of Lake Bonney (probably associated with the exchange flows between these basins).