Differential toxic sensitivity of crude oil in fish embryos depending on weathering status

Abstract

Two crude oils from distinct sources were similarly toxic to fish embryos; their state of weathering (polynuclear aromatic hydrocarbon, PAH, composition) was the most important determinant of toxicity. Zebrafish embryos were independently exposed to two oils, Iranian heavy crude oil (IHCO) and weathered Alaska North Slope crude oil (ANSCO), with two different exposure methods, water-accommodated fractions of oil and oiled gravel effluent. Overall, the two types of crude oil produced highly similar toxicity, primarily characterized by the well-known effects on cardiac function. Responses also included edema, intracranial hemorrhaging, caudal defects, and cytochrome P4501A induction. Mechanisms of cardiotoxicity were probably mixed and may have shifted from a predominantly aryl hydrocarbon receptor-independent mode during acute exposure and early weathering to a multiple pathway or synergistic mode with prolonged weathering and increased proportions of dissolved alkyl-PAHs. While there is value in continued comparisons of crude oils from a wider range of sources, our results indicate that the large body of knowledge acquired from the study of ANSCO is directly relevant to understanding the impacts of other crude oil spills.tly exposed to two oils, Iranian heavy crude oil (IHCO) and weathered Alaska North Slope crude oil (ANSCO), with two different exposure methods, water-accommodated fractions of oil and oiled gravel effluent. Overall, the two types of crude oil produced highly similar toxicity, primarily characterized by the well-known effects on cardiac function. Responses also included edema, intracranial hemorrhaging, caudal defects, and cytochrome P4501A induction. Mechanisms of cardiotoxicity were probably mixed and may have shifted from a predominantly aryl hydrocarbon receptor-independent mode during acute exposure and early weathering to a multiple pathway or synergistic mode with prolonged weathering and increased proportions of dissolved alkyl-PA