A one-dimensional transient model is developed to simulate observed population dynamics of a small flagellate (Cryptomonas ovata) in southern Kootenay Lake, B.C., during a 1-year period (1 June 1974-31 May 1975). The model considers advective displacement of C. ovata as water flows from its southern entrance into the lake and moves northward toward sampling sites. Specific growth rate is computed from an experimentally determined function of mean irradiance, water temperature, and nutrient (ammonium and phosphate) concentration in the upper 10 m of the water column. Cell losses are assumed to result from zooplankton grazing and inhibition due to presence of the blue-green alga Anabaena.
The model simulates well the timing and magnitude of all observed population changes and, more importantly, it gives insight into the important mechanisms which regulate population density of C. ovata in this natural system.