Biomarkers in fish from dioxin-contaminated fjords

Abstract

The Grenland fjords, southern Norway, have been heavily contaminated by dibenzo-p-dioxins and dibenzofurans (dioxins) over decades through inputs from a magnesium smelter. Despite radically decreased inputs since 1990, there are still high levels of dioxins in both biotic and abiotic components of the fjords. The aim of the study was to establish whether biomarkers’ responses in three fish species, Atlantic cod (Gadus morhua L.), sea-trout (anadromous brown trout, Salmo trutta L.) and flounder (Platichthys flesus L.), could be used to discern the effects in the most contaminated ecosystem, Frierfjord, from the effects in the adjacent, less-contaminated ecosystem, Eidangerfjord. Biomarker responses clearly indicated that the three fish species were affected by dioxin exposure. Phase I responses in cod and trout could be used to differentiate exposure in the two fjord ecosystems. Phase II responses (glutathione S-transferase) in cod and trout similarly indicated a higher dioxin exposure in Frierfjord compared with Eidangerfjord. Results for glutathione S-transferase and glutathione reductase indicated different exposure levels in the two fjords, but also showed seasonal variability, and the results highlighted the need for baseline data for these biomarkers.

Keywords: :

• Dioxins
• Atlantic cod (Gadus morhua L.)
• sea-trout (Salmo trutta L.)
• flounder (Platichthys flesus L.)
• biomarkers

Acknowledgements

The crew of the R/V G. M. Dannevig is thanked for assistance during sampling. The able laboratory assistance of Harry Efraimsen, Åse Bakketun and Åse Kristine Rogne at NIVA's laboratory is gratefully acknowledged. The study was supported financially by the Research Council of Norway (Contract No. 139032/720; The PROFO programme) and Norsk Hydro. The project was coordinated by Kristoffer Næs, NIVA. Other participating institutions in the larger programme were the Institute of Marine Research, Flødevigen, Norway; the Norsk Hydro Research Center, Norway; the University of Stockholm, Sweden; and the Norwegian Geotechnical Institute, Norway.