Geographical Differences in Behavioral Responses to Hypoxia: Local Adaptation to an Anthropogenic Stressor?

Stressors resulting from, or exacerbated by, human activities increasingly alter ecological systems. Behavioral responses that enhance survival of stressed individuals may be critical for local populations to persist. Although the types and intensities of stressors can vary over the geographic range of a species, little is known regarding geographical variation in adaptive behavioral responses to stressors, especially in marine and estuarine species subject to human impact. To explore varied behavior in response to low dissolved oxygen (a human perturbation), we examined two geographically distinct populations of the copepod, Acartia tonsa. Chesapeake Bay copepods, historically exposed to oxygen gradients, avoided hypoxic bottom waters. In contrast, Florida copepods not typically exposed to hypoxia did not avoid lethal oxygen concentrations. Our results suggest that local behavioral adaptations may result from consequences of anthropogenic perturbations and may limit the ability to apply biological data across regions. Geographical differences in behavioral responses of important prey species may also result in geographic variation in the severity of disruption of aquatic food webs.