Responses of juvenile southern flounder exposed to Deepwater Horizon oil-contaminated sediments.

The Deepwater Horizon oil spill released millions of barrels of crude oil into the northern Gulf of Mexico, much of which remains associated with sediments and can have continuing impacts on biota. Juvenile southern flounder (Paralichthys lethostigma) were exposed for 28 d in the laboratory under controlled conditions to reference and Deepwater Horizon oil-contaminated sediments collected from coastal Louisiana to assess the impacts on an ecologically and commercially important benthic fish. The measured polycyclic aromatic hydrocarbon (PAH) concentrations in the sediments ranged from 0.25 mg/kg to 3940 mg/kg suite of 50 PAH analytes (tPAH50). Mortality increased with both concentration and duration of exposure. Exposed flounder length and weight was lower compared to controls after 28 d of exposure to the sediments with the highest PAH concentration, but condition factor was significantly higher in these fish compared with all other treatments. Histopathological analyses showed increased occurrence of gill abnormalities, including telangiectasis, epithelial proliferation, and fused lamellae in flounder exposed to sediments with the highest tPAH50 concentrations. In addition, hepatic vascular congestion and macrovesicular vacuolation were observed in flounder exposed to the more contaminated sediments. These data suggest that chronic exposure to field collected oil-contaminated sediments results in a variety of sublethal impacts to a benthic fish, with implications for long-term recovery from oil spills. Environ Toxicol Chem 2017;36:1067-1076. © 2016 SETAC.