The Integrated Use Of Chemical And BiochemicalMarkers For Assessing The Effects Of The AegeanSea Oil Spill In The Galicia Coast (NW Spain)

Abstract

The spatial distribution and temporal evolution of petrogenic and pyrolytic hydrocarbons in the Galicia coast (NW Spain), following the Aegean Sea oil spill, were investigated through a detailed study of hydrocarbon (fossil) markers in surface sediments and bivalves (mussels and clams). Sublethal responses in mussels were also assessed by the determination of several biomarkers such as the cytochrome P450 system, antioxidant enzymes and lipid peroxidation. Triterpane and sterane distributions were useful in tracing, respectively, the oil source and weathering (degradation) along the survey period (3, 6, 9, 12 and 34 months after the accident). Within the aromatic fraction, aromatized steranes were also useful source indicators and oil degradation was also evidenced by the decrease of certain methyl dibenzothiophene isomers. Combustion derived polycyclic aromatic hydrocarbons, produced in the tanker wreck, were widely distributed in the area and found to be more persistent than the petrogenic ones, although less bioavailable. A significant decline of the hydrocarbon contents was evident from 3 to 6 months. However, one year later, an incidental increase was observed in some bivalves, probably due to the resuspension of the subsurface polluted sediments by the winter stormy weather. Among the studied biomarkers, a significant induction of the cytochrome P450 content and lipid peroxidation was detected in mussels collected near the wreck point six months after the spillage. Besides the strong seasonality observed in some biomarkers, oxidative damage still persisted one year later.