Oil exposure impairs predator–prey dynamics in larval red drum (Sciaenops ocellatus)

The 2010 Deepwater Horizon (DWH) oil spill in the Gulf of Mexico was the largest spill in recent history and led to the exposure of many commercially and ecologically important fish species. Crude-oil exposure is known to result in compromised cardiorespiratory function and swim performance of fishes, presumably altering ecological performance by impairing the ability to capture prey or evade predators. However, this has yet to be empirically tested. This study assessed the impacts of oil exposure on thigmotaxis (avoidance of exposed areas), routine activity, and prey-capture ability in larval red drum (Sciaenops ocellatus) by using environmentally relevant concentrations of weathered-oil water-accommodated fractions (0-55.9 mu g L-1 of total polycyclic aromatic hydrocarbons, sigma PAH). Oil exposure caused a dose-dependent increase in time spent in the exposed area of the arena, with an average three-fold increase at the highest dose, suggesting increased risk-taking. Although increased risk-taking resulted in 14% more area explored, oil-exposed individuals were significantly slower to catch prey and caught 67% less prey overall. Prey-capture ability did not appear to be related to cardiorespiratory or swimming impairments, because oil-exposed fish exhibited routine swim speeds and the distance travelled similar to those of the control, suggesting an alternate route of toxicity, such as cognitive impairments.