Comparison of Demographic and Individual Based Models Examining Effects of Drought On Fish Population Dynamics, Refuge Use and Species Persistence At Multiple Spatial Scales

Drought and summer drying can be important disturbance events in many small streams that can have strong effects on fish population dynamics, refuge use and species persistence.  We developed and compared demographic and individual based models to examine effects of drought on fish population dynamics, refuge use and species persistence.  We used empirical studies from Ozark Highland stream fishes to parameterize models.  Model results from individual based models showed that drought intensity was negatively related to fish density and to species persistence, but this was species and habitat dependent.  Extinction probabilities were low for all species populations due to metapopulation dynamics and refuge habitats maintaining populations.  Results from demographic and individual based models will be compared.  We expect that demographic models will show greater extinction probability.  Trade-offs exist between model realism, generality and precision for each model type.  Constraints and opportunities in model development and parameterization should be matched to the objectives of the study.