Aquatic snails detect and avoid both heavy metals and fright odor on sand substrates

Organisms often face a patchy distribution of stressors. Both abiotic heavy metal pollutants from mine wastes and biotic predators are often not distributed randomly. We tested the ability of aquatic pulmonate snails (Physella columbiana) to detect and adaptively avoid these stressors. Using a partially submerged sand substrate we found that the snails avoided areas with high concentrations of heavy metals and also reduced their activity levels when in the presence of crushed-snail extract - an indicator of predation. A policy suggestion that results from these results is that snail exposure in the field may best be determined by examining the lower levels of patchily distributed metals, i.e., hot patches may be behaviorally avoided.