Phototoxicity Assessments of Field Sites in Barataria Bay, Louisiana, USA, and Heavily Weathered Macondo Crude Oil: 4 Years after the Deepwater Horizon Oil Spill

Abstract

The Deepwater Horizon oil spill resulted in the release of large amounts of crude oil into waters of the Gulf of Mexico (USA). A significant portion of the oil reached coastal waters and shorelines where aquatic organisms reside. Four years after the spill, oil remains in small quantities along the coast. Given the high volume of oil coupled with the high ultraviolet light intensities of the Gulf of Mexico, continued polycyclic aromatic hydrocarbon phototoxicity may be occurring in the Gulf region. The objective of the present study was to determine the potential for phototoxicity at 5 field sites (oiled, remediated, and unoiled) in Barataria Bay (LA, USA) to caged mysid shrimp and sheepshead minnows and to evaluate the phototoxic potential of field‐collected oil water accommodated fractions (WAFs). Water chemistries were similar between field‐collected oil WAFs and ambient waters, excluding the most oiled field site. Field bioassays indicated no phototoxic risk of heavily weathered crude oil under the highly turbid conditions present during the study. Laboratory WAFs of field‐collected oil resulted in phototoxicity to mysid shrimp, suggesting a potential for phototoxicity of heavily weathered crude oil remaining in the Gulf of Mexico. Environ Toxicol Chem 2019;38:1811–1819. © 2019 SETAC

Deepwater Horizon oil spill, Phototoxicity, Polycyclic aromatic hydrocarbons, Water accommodated fractions, Toxic effects