Previous oil exposure alters oil avoidance behavior in a common marsh fish, the Gulf Killifish Fundulus grandis

Oil spills threaten the structure and function of ecological communities. In the northern Gulf of Mexico, the 2010 Deepwater Horizon spill was among the largest marine disasters in history. While many predicted catastrophic consequences for nearshore fishes, field studies indicate surprising resilience in populations and communities. One potential mechanism for this resilience is the recognition and behavioral avoidance at small spatial scales of the toxic chemical constituents found in oil. Previous research indicates many marsh fishes have the capacity to avoid oil contaminated areas. Here, we test whether prior oil exposure of a common marsh fish, the Gulf killifish Fundulus grandis, alters this avoidance response. Using choice tests between unoiled and a range of oiled sediments, we found that, even at low levels of previous exposure, killifish lose recognition of oiled sediments. Preference for unoiled sediments was lost across the entire range of oil concentrations tested here after oil exposure, and some evidence for preference of oiled sediments was even demonstrated. These results provide evidence for lack of response to toxic environments in exposed individuals, suggesting sublethal impairment of sensory mechanisms on an individual level despite organism survival. Future research should highlight additional sublethal consequences that affect ecosystem and food web functioning.