Effects of chronic exposure to petroleum hydrocarbons on two species of marine fish infected with a hemoprotozoan, Trypanosoma murmanensis

• Published in: Canadian Journal of Zoology
• Main Author: Khan, R. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1987
• Subjects: atlantic cod
• Online Access: http://dx.doi.org/10.1139/z87-410; http://www.nrcresearchpress.com/doi/pdf/10.1139/z87-410

The present study was undertaken to ascertain the effects of a blood protozoan, Trypanosoma murmanensis, on two species of marine fish exposed to petroleum hydrocarbons. Infected juvenile and adult winter flounder were exposed for 6 weeks to sediment contaminated with a Venezuelan crude (total hydrocarbon concentration, 2600–3200 μg/g) whereas Atlantic cod were exposed to water-accommodated fractions (50–100 μg/L) for 12 weeks. Three other groups, uninfected controls, fish infected with trypanosomes only, and oil-treated, uninfected fish, were held in aquaria in a continuously flowing seawater system. Mortality was higher in the infected, oil-treated flounder and subadult cod than in the trypanosome-infected only, oil-treated, and control groups. Death in oil-treated flounder was associated with severe tail rot and hypersecretion of mucus from the gills, whereas blood values (hematocrit, hemoglobin, total plasma protein) were significantly depressed in both infected groups. Low body condition, excessive mucus secretion by the gills, and retarded gonadal development were observed in adult, oil-treated cod but these were more pronounced in the infected, oil-treated groups. Prevalence of the infection and parasitemias were higher in the oil-treated groups than in untreated fish. These results provide evidence that the combined effects of parasites and chronic oil pollution can not only cause mortality but can also jeopardize health and reproduction in surviving fish.