Exposure to ultraviolet radiation late in development increases the toxicity of oil to mahi‐mahi (Coryphaena hippurus) embryos

Abstract

The Deepwater Horizon oil spill in 2010 overlapped with the spawning of many pelagic fish species in the Gulf of Mexico, including mahi-mahi (Coryphaena hippurus). Polycyclic aromatic hydrocarbons (PAHs) released during the spill have been shown to cause photo-induced toxicity under ultraviolet (UV) radiation. In the present study, mahi-mahi embryos were exposed to high-energy water accommodated fractions of source and naturally weathered oils for up to 48 h. The timing of co-exposure with UV radiation varied between an early development exposure for 8 h or a late development exposure for 8 h. The UV co-exposure had a photo-induced toxic effect on hatching success for all oil types and exposure scenarios. A more sensitive developmental window to photo-induced toxicity was observed when UV exposure occurred late in development. Source Oil B was over 6-fold more toxic, and Massachusetts source oil was 1.6-fold more toxic when the embryos were co-exposed to UV light late in development. Furthermore, weathered oil from the surface co-exposure with UV late in development resulted in bradycardia in the mahi-mahi. The present study provides evidence that the developmental window when UV co-exposure occurs has a significant effect on the degree of photo-induced toxicity of oil and that UV co-exposure may exacerbate long-term cardiac effects in developing fish. Environ Toxicol Chem 2017;36:1592-1598. © 2016 SETAC.

Mahi‐mahi (Coryphaena hippurus) life development: morphological, physiological, behavioral and molecular phenotypes

“…Indeed, during the last few decades, mahi has become an emergent model for examining population genetics, developmental physiology, metabolic responses, nutritional physiology, egg and larval performance over time, and climate change effects . Mahi have also been studied extensively regarding the impact of environmental toxicants . The emergence of this model fish has been accelerated by the need to develop more sophisticated scientific approaches for understanding the impact of environmental stressors, especially the impacts of the Deepwater Horizon Oil spill in 2010.…”

Photo‐induced toxicity following exposure to crude oil and ultraviolet radiation in 2 Australian fishes

“…Crude oil consists of a complex mixture of a range of petroleum hydrocarbons, including alkanes, branched alkanes, monoaromatic hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs; Reddy et al ), with slight compositional differences based on the source of the oil and the weathering state. Some PAHs found in crude oil have photodynamic properties responsive to wavelengths of light in the ultraviolet A (UVA) spectrum of sunlight, causing photo‐induced toxicity (Oris and Giesy ; Holst and Giesy ; Diamond et al ; Alloy et al , , ; Sweet et al ). Specifically, photodynamic PAHs are activated to an excited state in the presence of UV light, resulting in the production of excited singlet and triplet state molecules (Stieglitz et al ).…”

“…These molecules are highly reactive and can interact with biological tissue, resulting in oxidative stress and increased toxicity. Ultraviolet light has been shown to enhance the toxicity of photodynamic PAHs by 10 to 100× in aquatic organisms (Oris and Giesy ; Holst and Giesy ; Alloy et al , , ; Stieglitz et al ; Sweet et al ).…”

Estimating incident ultraviolet radiation exposure in the northern Gulf of Mexico during the Deepwater Horizon oil spill

“…These PAH concentrations are generally below those required to cause acute mortality through other modes of toxicity; however, developmental exposure to similar concentrations of oil has been shown to lead to physiological abnormalities associated with long‐term fitness costs, most notably cardiotoxicity (Incardona et al , ; Mager et al ; Khursigara et al ; Sweet et al ). Cardiotoxicity has been observed in early life stages of a variety of ecologically and commercially important fish species in the Gulf of Mexico, at concentrations less than 15 μg/L tPAH50 (equivalent to a nominal concentration of 0.75%) in the absence of UV (Incardona et al ; Khursigara et al ).…”

“…Adverse effects of photo‐enhanced or photo‐induced PAH toxicity have been well documented in aquatic vertebrate (Alloy et al , ; Finch and Stubblefield ), invertebrate (Alloy et al ; Finch and Stubblefield ; Damare et al ), and aquatic plant species (Huang et al ), and such effects occur at very low concentrations under both laboratory and field conditions. Organisms in early life stages exhibit increased sensitivity to photo‐induced PAH toxicity, compounding the risk of adverse effects in embryos and larval fish (Incardona et al ; Alloy et al , ; Sweet et al ).…”