Previous oil exposure alters Gulf Killifish oil avoidance behavior.

Oil spills threaten the structure and function of ecological communities. The spill was predicted to have catastrophic consequences for nearshore fishes, but field studies indicate resilience in populations and communities. Previous research indicates many marsh fishes exhibit avoidance of oil contaminated areas, representing one potential mechanism for this resilience. Here, we test whether prior oil exposure of Gulf killifish alters this avoidance response. Using choice tests between unoiled and oiled sediments at one of three randomized concentrations (low: 0.1 L oil m, medium: 0.5 L oil m, or high: 3.0 L oil m), we found that, even at low prior exposure levels, killifish lose recognition of oiled sediments compared to control, unexposed fish. Preference for unoiled sediments was absent across all oil concentrations after oil exposure, and some evidence for preference of oiled sediments at high exposure was demonstrated. These results highlight the lack of response to toxic environments in exposed individuals, indicating altered behavior despite organism survival. Future research should document additional sublethal consequences that affect ecosystem and food web functioning.