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108 Lake Ecosystems (Stratification and Seasonal Mixing Processes, Pelagic and Benthic Coupling)

Part 9. Ecological and Hydrological Interactions

  1. Darren L Bade

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa114

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Bade, D. L. 2006. Lake Ecosystems (Stratification and Seasonal Mixing Processes, Pelagic and Benthic Coupling). Encyclopedia of Hydrological Sciences. 9:108.

Author Information

  1. University of Wisconsin, Center for Limnology, Madison, WI, US

Publication History

  1. Published Online: 15 APR 2006

Abstract

Seasonal stratification in lakes is caused by the differential heating of surface waters, causing them to become less dense and buoyant above colder, denser water. Other forces oppose stratification, including wind energy and loss of heat from the surface. Wind imparts many types of motions to lake waters, each having distinct patterns, energy, and scales of mixing. Theoretical considerations are presented in detail on the expected response of lakes to physical forcing. In addition, empirical equations are given for diverse regions of the world to predict epilimnetic and thermocline depth and timing of stratification. Lake morphometry along with climatic conditions determines the depth of epilimnetic mixing. The seasonal patterns of mixing and stratification are observed in a northern temperate lake (Sparkling Lake, Wisconsin, USA). The influence of stratification and mixing on the coupling of benthic and pelagic zones through processes of sedimentation, resuspension, eddy diffusivity, and hypolimnetic entrainment are discussed. Through these mechanisms, the hydrodynamics of lakes directly and indirectly influence the chemical and biological environment of lake ecosystems.

Keywords:

  • stratification;
  • mixis;
  • thermocline;
  • epilimnion;
  • hypolimnion;
  • sedimentation;
  • sediment resuspension;
  • eddy diffusion;
  • hypolimnetic entrainment