Bioavailability of Crude Oil from Experimentally Oiled Sediments to English Sole (Parophrys vetulus), and Pathological Consequences

Abstract

English sole (Parophrys vetulus) were exposed to experimentally oiled (Alaskan North Slope crude oil) sediments over a 4-mo period to assess the bioavailability and tissue hydrocarbon distribution kinetics in flatfish. Data were also obtained on hydrocarbon related physiological changes and tissue pathology. Crude oil was mixed with aromatic hydrocarbon-free sediments to a concentration of 700 μg/g dry weight at the beginning of the experiment. During the 1st mo of the experiment this concentration decreased to 400 μg/g dry weight, and remained relatively stable during the remainder of the 4-mo period. Compositional changes were observed in the alkane and aromatic fractions, with a differential decrease in the substituted naphthalenes. Flatfish maintained in such oiled sediments readily took up alkane and aromatic petroleum hydrocarbons from these sediments, and accumulated these in skin, muscle, and liver; 1- and 2-methylnaphthalene and 1,2,3,4-tetramethylbenzene were accumulated to greater extent than other aromatics. Tissue hydrocarbons decreased with time, and after 27-d continuous exposure to oiled sediments only the liver contained detectable levels of hydrocarbons. After 2 mo < 2% of the initial aromatic hydrocarbon load could be detected, and only in the liver in flatfish that were continuously maintained on oiled sediments. Depuration of tissue aromatics differed for various aromatics, 1,2,3,4-tetramethylbenzene and 2-methylnaphthalene being most persistent. Depuration is thought to be due to induction of the aryl hydrocarbon hydroxylase system during initial exposure to oiled sediments. Concomitant with the high tissue hydrocarbon period were found enhanced weight loss and severe hepatocellular lipid vacuolization (HLV). Although the observations, on growth changes and liver pathology are preliminary, the data indicate the need for further detailed study of fish growth abnormalities and pathology in the presence of petroleum hydrocarbons. Key words: flatfish, crude oil, bioavailability, pathology, aromatic hydrocarbons, bottom sediments, depuration