A multitude of recent studies have documented the detrimental effects of crude oil exposure on early life stages of fish, including larvae and embryos. While polycyclic aromatic hydrocarbons (PAHs), particularly alkyl PAHs, are often considered the main cause of observed toxic effects, other crude oil derived organic compounds are usually overlooked. In the current study, comprehensive two-dimensional gas chromatography coupled to mass spectrometry was applied to investigate the body burden of a wide range of petrogenic compounds in Atlantic haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) embryos that had been exposed to sublethal doses of dispersed crude oil. Several groups of alkylated monoaromatic compounds (e.g. alkyl tetralins, indanes and alkyl benzenes), as well as highly alkylated PAHs, were found to accumulate in the fish embryos upon crude oil exposure. To investigate the toxicity of the monoaromatic compounds, two models (1-isopropyl-4-methyltetralin and 1-isopropyl-4-methylindane) were synthesized and shown to bioaccumulate and cause delayed hatching in developing embryos. Minor developmental effects, including craniofacial and jaw deformations and pericardial edemas, were also observed at the highest studied concentrations of the alkylindane.

In the framework of the ICON project, environmental genotoxicity and cytotoxicity levels were assessed in blood erythrocytes of dab (Limanda limanda) and haddock (Melanogrammus aeglefinus) collected at 25 stations in the North Sea and near the coast of Iceland in August–October 2008. Micronuclei, nuclear buds and bi-nucleated cells with nucleoplasmic bridges were assessed as environmental genotoxicity biomarkers, and the frequency of fragmented-apoptotic and bi-nucleated erythrocytes were assessed as environmental cytotoxicity biomarkers. The lowest frequencies of genotoxic and cytotoxic abnormalities were detected in fish from the Icelandic study stations. The highest frequencies of abnormalities were recorded in dab from the Dogger Bank and the German Bight, in haddock from the Egersund Bank and from an area off the Firth of Forth (North Sea). In fish from the Icelandic reference area, frequencies of genotoxicity and cytotoxicity responses were significantly lower than in fish from most areas of the North Sea.