An algorithm for modifying biological rates as a function of temperature has been developed using the basic form of the logistic equation. Versions of this basic algorithm are then used to modify growth, respiration, and mortality rates as a function of four characteristic temperatures.
One of the earliest formulations used to modify reaction rates as a function of temperature was the Q•0 or van't Hoff equation. The Q•0 formulation iswhere k2 is the reaction rate at temperature t2 and k• is the reaction rate at temperature tl.
Ecosystem models require extensive data for initialization and calibration. Since data collection is expensive and time-consuming, it should be guided by knowledge of the model's sensitivity to initial conditions, coefficients, and update intervals. These factors were studied using an ecological model of a reservoir. For this model, it was found that (a) biological and chemical variables need to be considered in addition to temperature during calibration, (b) changes in the effective diffusion coefficients produce the greatest changes in the model's responses, (c) nutrient update intervals of less than one week yield results similar to those for one week but dissimilar to those for two weeks or one month, and (d) nutrient concentrations strongly affect the model's sensitivity to small changes in a number of coefficients.
Destrpy this report when no longer needed. Do not return it to the originator. The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.
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