Spatially explicit population models offer a means of incorporating both general information on habitat use and specific information about local environmental stressors. Understanding the baseline distribution and density of a species within an area is a critical component for determining population-level impacts of environmental contaminants. However, site-specific ecological risk assessments are often limited by a lack of information on population-level effects of contaminant exposure and local habitat suitability of target species. We developed a habitat suitability model for sheepshead minnow (Cyprinodon variegatus) as an initial step in predicting species distribution. During four consecutive seasonal surveys, sheepshead minnow densities were recorded at randomly-selected sites within wetland habitats in the Pensacola Bay estuary along with physical habitat quality variables, including sediment grain size, total organic carbon content, water depth, water temperature, salinity, pH, and dissolved oxygen. Field data were analyzed using generalized linear models to develop a habitat suitability model that predicts fish presence and density as a function of key environmental variables.
Results/Conclusions
Preliminary results indicate that seasonal variation in habitat temperature and water depth most influenced sheepshead minnow distribution. The general habitat model will be combined with density dependent population dynamics and laboratory-determined dose-response curves describing contaminant effects to simulate sheepshead minnow population response for potentially contaminated sites. Evaluation of our habitat model will be conducted through validation of species presence and density in nearby Mobile Bay across known contamination gradients. Our habitat suitability model provides a generally applicable template for incorporating natural environmental variability when conducting probabilistic risk assessments of contaminant exposure on similar fish species in estuarine environments.
