Determining oxidative stress and EROD activity in dab (Limanda limanda) in the North and Baltic Seas

- This work is a part of the ICON project that investigated different strategies to assess the health of the marine environment around the north sea.
- We describe an important aspect of marine health assessments, namely subcellular biomarkers for oxidative stress and PAH exposure.
- Fish were sampled out at sea where the levels of pollutants are relatively low. However, we were able to demonstrate minor effects of exposure.
- This demonstrates that subcellular biomarkers could be an important addition to the health assessment of the marine environment.

The North and Baltic Seas are heavily trafficked marine areas with extensive anthropogenic activities, including cargo and fishing vessels, waste dumping, oil platforms, industrial activities and contamination from coastal runoff. In order to evaluate the environmental health of these regions, we used the demersal fish dab (Limanda limanda) as a sentinel species. The current study used well-established biomarkers for PAH exposure and oxidative stress, measuring EROD activity, the acute antioxidant response as well as oxidation of proteins detected as protein carbonyl levels. Results show the strongest biomarker results in an area with extensive oil drilling, where dab displayed high levels of EROD activities. This was also seen in dab captured in the Baltic Sea where elevated levels of oxidized glutathione and a trend towards higher EROD activity were observed. The obtained results did, however, not indicate a coherent biomarker response. The study was conducted off shore where many areas have presumably low levels of pollutants, and we could detect minor effects using the biomarker approach.