SS1.05 How Will Aquatic Ecosystems Respond to Climate Change?
Date: Tuesday, June 11, 2002
Time: 4:00:00 PM
Location: Oak Bay
 
SwiftTJ, Dept. Envir. Studies & Policy, UC Davis, Davis, CA, USA, tjswift@ucdavis.edu
Reuter, J, E, Dept. Envir. Studies & Policy, UC Davis, Davis, CA, USA, jereuter@ucdavis.edu
Goldman, C, R, Dept. Envir. Studies & Policy, UC Davis, Davis, CA, USA, crgoldman@ucdavis.edu
Schladow, S, G, Dept. Civ. & Envir. Eng., UC Davis, Davis, CA, USA, gschladow@ucdavis.edu
Mitchell, B, G, Scripps Inst. Oceanogr., La Jolla, CA, USA, gmitchell@ucsd.edu
 
A BIOGEOOPTICAL MODEL FOR AN ULTRAOLIGOTROPHIC LAKE: LAKE TAHOE, CA-NV, USA
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Lake Tahoe, CA-NV, USA, is a 500 km sq., 500 m deep ultra-oligotrophic lake revered for its blue waters and remarkable transparency. It is in the early stages of eutrophication. The watershed (1.6 times lake area) has also been extensively altered by development. Increased primary production and sediment loading have been accompanied by a loss of about 0.5 m/y in Secchi disk transparency, with significant seasonal and interannual variation. Recent annual mean Secchi depths are approx. 21 m (max. 33 m; min. 15 m). We have developed a clarity model that takes into account organic and inorganic particles and dissolved organic matter. Most of the loss of clarity is due to scattering by particles, followed by algal absorption, with a minor contribution from CDOM absorption. While organic particles (diatoms and their detritus) form the numerical majority and are the dominant cause of clarity loss, silts and clays play an important role due to their high scattering efficiency. We discuss the development and testing of the model, its use in Tahoe basin land use planning, and potential application to other settings.