engleski

Effect of heavy fuel oil (HFO) on embryo-larval stage of zebrafish (Danio rerio) and establishment of biomarker protocols in marine medaka (Oryzias melastigma)

After discovery of oil resource under Arctic bed, new shipping routes and more traffic are expected, hence there is a greater risk of oil spill. Knowledge about the fate and behavior of heavy fuel oil (HFO), that is mostly used for ship transportation, is important in order to develop appropriate response strategy in cold areas. In this context, in the present thesis the effects of the application of a chemical dispersant on HFO IFO180 was investigated. The toxicity was assessed using zebrafish (Danio rerio) as model organism. Water accommodated fractions of dispersed HFO were toxic for 50% of the embryos at 2.9% of 1:200 stock solution. Further, EC10, EC20 and EC50 concentrations significantly induced ethoxyresorufin-o- deethylase (EROD) activity, but had no effect on catalase (CAT) and acetylcholinesterase (AChE) activity. In a swimming behavior assay on light-dark transition zebrafish larvae exposed to HFO WAFs showed reduced movement in dark conditions compared to control. Since sensitivity of freshwater and marine species to environmental pollutants could be significantly different, biomarker protocols using marine medaka (Oryzias melastigma) were established. Marine medaka showed great potential as saltwater alternative to zebrafish with induced EROD and CAT activity (benzo(a)pyrene 10-40 µg/L) and inhibited AChE (paraoxon-methyl 10-40 mg/L) in embryos treated with positive control substances. From three different development stages (2, 6 and 8 dpf), the late pre-hatched stage (8 dpf) showed the best results.

oil spill ; zebrafish ; embryo toxicity ; chemical dispersant ; marine medaka ; enzyme activity ; biomarker protocols

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