Individual and Combined Toxicity of Polycyclic Aromatic Hydrocarbons Phenanthrene and Fluoranthene in Freshwater Amphipod Gammarus pulex (L., 1758) (Amphipoda: Gammaridae)

The combined toxicity of polycyclic aromatic hydrocarbons on freshwater amphipod Gammarus pulex was investigated. The 14-day LC50 values of fluoranthene, phenanthrene and their combination for G. pulex were determined as 5.88±0.23, 8.31±0.57 and 7.00±0.33 mg/L, respectively. To evaluate the single and combined toxicity, sublethal concentrations of fluoranthene, phenanthrene and their combination were exposed to G. pulex for 14 days. Acetylcholinesterase, glutathione-s-transferase and cytochrome P450 1A1 enzymes were measured as biomarkers. Acetylcholinesterase activities showed significant inhibition at the end of 7 and 14 days. No statistically significant change was observed in cytochrome P450 1A1 levels at the end of the 7th day, but a significant increase was detected at the end of the 14th day. A significant inhibition was observed in glutathione-s-transferase activities at the end of the 7th and 14th days. Statistically significant changes were observed in all parameters when the application times are compared. It was determined that G. pulex exposed to different concentrations of phenanthrene and fluoranthene individually and in combination caused significant changes in activites of the all measured enzymes. It was concluded that the cytochrome P450 1A1, glutathione-s-transferase and acetylcholinesterase enzymes in G. pulex are useful biochemical markers for the determination of polycyclic aromatic hydrocarbon toxicity.