Nonlethal Biomarkers of Oxidative Stress in Oiled Sediment Exposed Southern Flounder (Paralichthys lethostigma): Utility for Field-Base Monitoring Exposure and Potential Recovery.

The Deepwater Horizon (DWH) blowout resulted in the deposition of toxic polycyclic aromatic hydrocarbons (PAHs), in the coastal sediments of the Gulf of Mexico. The immediate effects on an ecosystem from an oil spill are clearly recognizable, however the long-term chronic effects and recovery after a spill are still not well understood. Current methodologies for biomonitoring wild populations are invasive and mostly lethal. Here, two potential nonlethal biomonitoring tools for the assessment of PAH toxicity and induced biological alterations in the field, were identified using laboratory-validated methods. In this study, subadult southern flounder (Paralichthys lethostigma) were chronically exposed to DWH surrogate oiled sediments for 35 days; a subset of these exposed flounder were then provided a clean nonexposure period to ascertain the utility of selected biomarkers to monitor recovery post exposure. After chronic exposure, there was an increase in gene expression of cytochrome P450 1A but not glutathione S-transferase. There was also a notable imbalance of oxidants to antioxidants, measured as reduced glutathione, oxidized glutathione, and their ratio in the blood. Evidence of subsequent oxidative damage due to chronic exposure was found through lipid peroxidation and DNA damage assessments of liver, gill, and blood.

Species-specific metabolism of naphthalene and phenanthrene in 3 species of marine teleosts exposed to Deepwater Horizon crude oil.

The 2 most abundant polycyclic aromatic hydrocarbons (PAHs) measured in Deepwater Horizon crude oil, naphthalene and phenanthrene, and their associated homologs have both been shown to be acutely toxic in fish. Although fish have a relatively high metabolic capacity for PAHs, hydroxylated PAH (OH-PAH) derivatives formed during the initial metabolic response can negatively impact the health of fish. Species-specific metabolism of naphthalene and phenanthrene was evaluated in 3 marine teleosts, red drum (Scianops ocellatus), Florida pompano (Trachinotus carolinus), and southern flounder (Paralichthys lethostigma). Fish were exposed to Deepwater Horizon crude oil by intraperitoneal injections at time 0 and 48 h, with bile sampling events at 24 and 72 h post injection. The data suggested metabolic induction in Florida pompano and red drum, whereas southern flounder may have demonstrated metabolic fatigue. By 24 h post injection, overall profiles of red drum and southern flounder were dominated by hydroxylated phenanthrene metabolites; conversely, the Florida pompano profiles were dominated by monohydroxylated naphthalenes. In addition, Florida pompano had faster overall relative biotransformation rates, suggesting their potential decreased susceptibility to adverse effects. Red drum and southern flounder had much lower relative biotransformation rates, indicating their probable susceptibility to adverse outcomes after naphthalene and phenanthrene exposures. To our knowledge, the present study is the first to investigate monohydroxylated PAHs in fish exposed to Deepwater Horizon oil. Environ Toxicol Chem 2017;36:3168-3176. © 2017 © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.