The Population Ecology Section investigates the impact of physical, chemical and biotic stressors on aquatic and terrestrial organisms and their populations. In studies with threatened and endangered species, the investigations are often conducted from a multiple stressor perspective, since hazardous variables often co-occur. Thus, for example, investigations into the cause of declining amphibian populations considered specific contaminants, as well as solar ultraviolet radiation, pathogens, predators and competitors.

Evaluations of chemical products that may be applied in the habitats of sensitive species during the course of resource management include measures of toxicity, environmental persistence, and an evaluation of envirornmental variables that may influence exposure. Such products include herbicides for the control of invasive species within the habitats of native species, as well as chemical products broadly applied in the control of forest fires and road dust abatement. Risk assessment procedures are routinely applied to evaluate the outcome of resource management options in a diversity of scenarios including water diversion projects, invasive species control, natural resource damage assessment, and environmental restoration of impacted sites.