Abstract |
Recent qualitative studies of the effects of toxicants on populations have resulted in conjectures about the role played by a dose-response function in determining the existence of multiple equilibrium states, consequences of modeling chemical dynamics by first order laws, and problems arising when uptake or toxicant can occur through both environmental and food chain pathways. A brief synthesis, focusing on the sensitivity of the models to the representation of the population, of these studies is presented. Then, some new persistence-extinction results for resource-consumer-toxicant interactions are indicated. An analytical approach is used to address a set of generic models each employing a dynamic submodel of the population, a dynamic formulation for environmental concentration of a toxicant, and a dynamic concentration of toxicant in the individual organisms. Conclusions, derived from the models by analytic techniques, are phrased in terms of system level parameters that govern persistence or extinction of the model population. (Copyright (c) 1984 Elsevier Science Publishers B.V.) |