LINKING LIFE-HISTORY THEORY, ENVIRONMENTAL SETTING, AND INDIVIDUAL-BASED MODELING TO COMPARE RESPONSES OF DIFFERENT FISH SPECIES TO ENVIRONMENTAL-CHANGE

We link life history theory, environmental setting, and individual-bas ed modeling to compare the responses of two fish species to environmen tal change. Life history theory provides the framework for selecting r epresentative species, and in combination with information on importan t environmental characteristics, it provides the framework for predict ing the results of model simulations. Individual-based modeling offers a promising tool for integrating and extrapolating our mechanistic un derstanding of reproduction, growth, and mortality at the individual l evel to population-level responses such as size-frequency distribution s and indices of year-class strength. Based on the trade-offs between life history characteristics of striped bass Morone saxatilis and smal lmouth bass Micropterus dolomieu and differences in their respective e nvironments, we predicted that young-of-year smallmouth bass are likel y to demonstrate a greater compensatory change in growth and mortality than young-of-year striped bass in response to changes in density of early life stages and turnover rates of zooplankton prey. We tested th is prediction with a simulation experiment. The pattern of model resul ts was consistent with our expectations: by the end of the first growi ng season, compensatory changes in length and abundance of juveniles w ere more pronounced for smallmouth bass than for striped bass. The res ults also highlighted the dependence of model predictions on the inter play between density of larvae and juveniles and characteristics of th eir zooplankton prey.