CS08 Biogeochemical Cycles
Date: Monday, June 10, 2002
Time: 11:45:00 AM
Location: Saanich
 
LueckeC, Utah State University, Logan, USA, luecke@cnr.usu.edu
 
MODELING BIOLOGICAL LINKAGES BETWEEN EPILIMNETIC AND METALIMNETIC REGIONS OF OLIGOTROPHIC LAKES
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A simulation model was developed to assess the interactions between spatially segregated phytoplankton assemblages and migrating zooplankton in oligotrophic lakes with deep chlorophyll layers. The model contained epilimnetic and metalimnetic depth strata. Heat, light, nutrients and zooplankton and phytoplankton populations moved between strata according to physical and biological principles. Incoming stream water and associated nutrients were split into epilimnetic and metalimnetic regions of the lake according to results of results of a spatially explicit physical model and dye studies on lakes in the Sawtooth Mountains of central Idaho. Results indicated that plunging stream inflows can contribute to the development of deep chlorophyll layers. Most simulation runs indicated that metalimnetic regions were responsible for higher zooplankton production and worked as a source in source/sink population dynamics. Movement of zooplankton across strata contributed to the nutrients available to phytoplankton in epilimnetic waters. These simulations also indicated that given hydrographs typical of montane, high elevation lakes, nutrient dynamics are regulated by stream inflows during the first month after ice-out, but regulated by internal nutrient recycling regimes from mid-summer to fall overturn.