, 2009). In cod the exposure conditions indicated by biliary PAH metabolites have been linked to cytochrome P450 1A protein (CYP1A) responses and formation of DNA adducts see more ( Aas et al., 2000a, Aas et al., 2001, Sanni et al., 2005 and Skadsheim et al., 2009). Other parameters analyzed in cod include

biliary AP metabolites, vitellogenin, zona radiata protein, glutathione S-transferase and gill histopathology. The surveys have mostly detected exposure to PAH and AP from PW and biomarker responses no further than 0.5–1 km from the discharge points, but in one survey effects out to 1.6 km were detected ( Sundt et al., 2008). Corresponding biliary PAH metabolites and biomarker responses in wild fish caught within 100 m from three Australian offshore platforms where the PW comes from a heavy crude oil also suggest that the effects were local Crizotinib order as no effects were detected at 5 km distance ( Gagnon, 2011). There is, however, a concern

that current methods are not sensitive enough to reveal subtle effects further out. Also, few of the biomarker endpoints look beyond the compensatory capacity of the organisms, and the significance of these responses for the fitness and survival of the organisms is still debated. Extrapolation from short-term biomarker effects in individual organisms to long term effects on populations and communities is inherently difficult ( Forbes et al., 2006), and the conclusion that impacts are largely local is still unverified ( Wells, 2005). Some fish species seem to be attracted to production platforms. Jørgensen et al. (2002) showed that about half the cod tagged near an NS platform remained there

or around neighboring platforms. Gill net catches have been PTK6 bigger near platforms than further away (Løkkeborg et al., 2002). Monitoring studies on free living fish in the NS have shown interesting results with respect to effects on biomarkers. Samples collected in 2002 from two areas with extensive oil and gas production showed induction on biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity in natural populations of haddock (Melanogrammus aeglefinus) ( Balk et al., 2011 and Grøsvik et al., 2010). Genotoxicity was reflected by a hepatic DNA-adduct pattern typical for exposure to a mixture of PAHs. Atlantic cod showed similar, but less pronounced responses. Repeated monitoring in 2005, 2008 and 2011 confirmed this pattern, although with weaker genotoxic signals in haddock from the northern NS (Tampen area). It is still not clear whether the effects are caused by PW contaminants, contaminated drill cuttings, smaller oil spills, or a combination of these sources ( Hylland et al., 2006). These findings as well as results from caging experiments have shown that individual fish can be affected sublethally in several ways by PW discharges ( Brooks et al., 2011b).