Candidate biomarker discovery in plasma of juvenile cod (Gadus morhua) exposed to crude North Sea oil, alkyl phenols and polycyclic aromatic hydrocarbons (PAHs).

In this study we have investigated protein changes in plasma of juvenile Atlantic cod (Gadus morhua) induced by crude North Sea oil and North Sea oil spiked with alkyl phenols and polycyclic aromatic hydrocarbons, a surrogate produced water composition. Using a proteomic approach, we identified 137 differentially expressed proteins at different levels of crude oil exposure. Many of the induced protein changes occurred at low levels of exposure. The results obtained with protein expression profiles after exposure to oil and surrogate produced water indicate effects on fibrinolysis and the complement cascade, the immune system, fertility-linked proteins, bone resorption, fatty acid metabolism as well as increased oxidative stress, impaired cell mobility and increased levels of proteins associated with apoptosis. Although the number of individuals and samples in this study is limited within each treatment group, the protein changes observed in this study represent a first screening for potential biomarker candidates in cod plasma reflecting potential effects of crude oil and produced water exposure on fish.

Relating biomarkers to whole-organism effects using species sensitivity distributions: a pilot study for marine species exposed to oil.

Biomarkers are widely used to measure environmental impacts on marine species. For many biomarkers, it is not clear how the signal levels relate to effects on the whole organism. This paper shows how species sensitivity distributions (SSDs) can be applied to evaluate multiple biomarker responses in species assemblages. To our knowledge, the present study compared for the first time SSDs based on biomarker response levels for marine species to a SSD for whole-organism responses. The comparison indicates that for exposure to dispersed oil in the marine environment, the selected biomarkers were, on average, 35- to 50-fold more sensitive than the whole-organism effect. At the 5% hazardous concentration derived from the SSD for whole-organism effects, which is a conservative threshold level, the potentially affected fraction of species showing biomarker response corresponds to approximately 80%. Variation in species sensitivity, expressed either as biomarker or as whole-organism response levels, were similar. Although uncertainties exist, the link between biomarkers and risk assessment presented here provides a preliminary guideline for deciding when biomarker responses likely are hazardous and, therefore, require further investigation.