Biomarker responses in Atlantic cod (Gadus morhua) exposed to produced water from a North Sea oil field: laboratory and field assessments.

Biological markers of produced water (PW) exposure were studied in Atlantic cod (Gadus morhua) in both laboratory and field experiments, using authentic PW from a North Sea oil field. In the laboratory study, the PW exposure yielded significantly elevated levels of metabolites of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs) in bile even at the lowest exposure dose (0.125% PW). Other biomarkers (hepatic CYP1A induction and DNA adduct formation) responded at 0.25% and 0.5% PW concentrations. In the field study, bile metabolite markers and hepatic CYP1A were clearly increased in fish caged close to the PW outfall. Induction of plasma vitellogenin was not found in laboratory or field exposures, suggesting that the levels of oestrogen agonists (such as APs) might not have been sufficient to elicit induction, under the present conditions. The applicability of the biomarkers for use in water column biomonitoring programs is discussed.

Tumor prevalence and biomarkers of genotoxicity in brown bullhead (Ameiurus nebulosus) in Chesapeake Bay tributaries.

We surveyed four Chesapeake Bay tributaries for skin and liver tumors in brown bullhead (Ameiurus nebulosus). We focused on the South River, where the highest skin tumor prevalence (53%) in the Bay watershed had been reported. The objectives were to 1) compare tumor prevalence with nearby rivers (Severn and Rhode) and a more remote river (Choptank); 2) investigate associations between tumor prevalence and polynuclear aromatic hydrocarbons (PAHs) and alkylating agents; and 3) statistically analyze Chesapeake Bay bullhead tumor data from 1992 through 2008. All four South River collections exhibited high skin tumor prevalence (19% to 58%), whereas skin tumor prevalence was 2%, 10%, and 52% in the three Severn collections; 0% and 2% in the Choptank collections; and 5.6% in the Rhode collection. Liver tumor prevalence was 0% to 6% in all but one South River collection (20%) and 0% to 6% in the three other rivers. In a subset of samples, PAH-like biliary metabolites and (32)P-DNA adducts were used as biomarkers of exposure and response to polycyclic aromatic compounds (PACs). Adducts from alkylating agents were detected as O6-methyl-2'-deoxyguanosine (O6Me-dG) and O6-ethyl-2'-deoxyguanosine (O6Et-dG) modified DNA. Bullheads from the contaminated Anacostia River were used as a positive control for DNA adducts. (32)P-DNA adduct concentrations were significantly higher in Anacostia bullhead livers compared with the other rivers. We identified alkyl DNA adducts in bullhead livers from the South and Anacostia, but not the Choptank. Neither the PAH-like bile metabolite data, sediment PAH data, nor the DNA adduct data suggest an association between liver or skin tumor prevalence and exposure to PACs or alkylating agents in the South, Choptank, Severn, or Rhode rivers. Logistic regression analysis of the Chesapeake Bay database revealed that sex and length were significant covariates for liver tumors and length was a significant covariate for skin tumors.

Biomarkers in natural fish populations indicate adverse biological effects of offshore oil production.

BACKGROUND: Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills. METHODS AND PRINCIPAL FINDINGS: Samples from natural populations of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs) were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea. CONCLUSION: It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production.

Water column monitoring of the biological effects of produced water from the Ekofisk offshore oil installation from 2006 to 2009.

The Norwegian water column monitoring program investigates the biological effects of offshore oil and gas activities in Norwegian waters. In three separate surveys in 2006, 2008, and 2009, bioaccumulation and biomarker responses were measured in mussels (Mytilus edulis) and Atlantic cod (Gadus morhua) held in cages at known distances from the produced water (PW) discharge at the Ekofisk oil field. Identical monitoring studies performed in all three years have allowed the biological effects and bioaccumulation data to be compared, and in addition, enabled the potential environmental benefits of a PW treatment system (CTour), implemented in 2008, to be evaluated. The results of the 2009 survey showed that caged animals were exposed to low levels of PW components, with highest tissue concentrations in mussels located closest to the PW discharge. Mussels located approximately 1-2 km away demonstrated only background concentrations of target compounds. Concentrations of polycyclic aromatic hydrocarbons (PAH) and alkyl phenol (AP) metabolites in the bile of caged cod were elevated at stations 200-250 m from the discharge. There was also a signal of exposure relative to discharge for the biomarkers CYP1A in fish and micronuclei in mussels. All other fish and mussel biomarkers showed no significant exposure effects in 2009. The mussel bioaccumulation data in 2009 indicated a lower exposure to the PW effluent than seen previously in 2008 and 2006, resulting in an associated general improvement in the health of the caged mussels. This was due to the reduction in overall discharge of PW components (measured as oil in water) into the area in 2009 compared to previous years as a result of the improved PW treatment system.

Genotoxicity in herring gulls (Larus argentatus) in Sweden and Iceland.

Adult and young herring gulls (Larus argentatus) in Sweden and Iceland were investigated with respect to DNA adducts, analysed with the nuclease-P1 version of the (32)P-postlabelling method, and micronucleated erythrocytes. Three important aims were: (1) to estimate the degree of exposure to genotoxic environmental pollutants in the Baltic Sea area and Iceland, (2) to evaluate the utility of the investigated biomarkers in birds, and (3) to investigate if there was any relationship between genotoxic effects and thiamine deficiency. The results demonstrate that both Swedish and Icelandic herring gulls are exposed to genotoxic pollution. Urban specimens have higher levels of DNA adducts than rural specimens, but background exposure to genotoxic environmental pollutants, such as PAHs, is also significant. In the herring gull the general level of DNA adducts in the liver seems to be higher than in fish. DNA adducts were most abundant in the liver, followed by the kidney, intestinal mucosa, and whole blood, in decreasing order. The frequency of micronucleated erythrocytes was probably slightly elevated in all the investigated sites, reflecting a significant background exposure. The level of DNA adducts was unrelated to the frequency of micronucleated erythrocytes, and both these variables were unrelated to symptoms of thiamine deficiency. The investigation confirmed the utility of DNA adducts, and probably also micronucleated erythrocytes, as biomarkers of genotoxicity in birds.

Bioaccumulation and biomagnification of organochlorines in a marine food web at a pristine site in Iceland.

Organochlorine (OC) bioaccumulation and biomagnification were studied in a marine food web at a pristine site in Iceland. The species studied were the gastropod and grazer chink shell (Lacuna vincta), the filter feeding bivalve blue mussel (Mytilus edulis), the predators butterfish (Pholis gunnellus), and the seabird black guillemot (Cepphus grylle), all sampled and analysed in 1996-1997. Individual OC levels were generally low in chink shell and blue mussels, somewhat elevated in the fish, and an order of a magnitude higher in the top predator black guillemot, except for Sigma HCH (hexachlorocyclohexane isomers) and Sigma chlordane levels, which were similar in all organisms, ranging from 10 to 36 ng/g lipid weight (lw). In the molluscs and fish, mean concentrations of Sigma PCB (polychlorinated biphenyl) ranged from 111 to 377 ng/g lw, Sigma DDT (dichlorodiphenyltrichloroethane) ranged from 19 to 65 ng/g lw, and HCB (hexachlorobenzene) ranged from 21 to 30 ng/g lw. The levels of same OCs in the black guillemot were on average 2352, 361, and 283 ng/g lw, respectively. The OC tissue concentrations in blue mussel and black guillemot are comparable to levels in Arctic and sub-Arctic regions, but OC levels in blue mussel tissue were an order of magnitude lower than found in the North Sea and the Baltic Sea. The relative composition of OCs were generally similar among species with the PCB congeners emerging as the most abundant compounds with levels an order of magnitude higher than the other compounds in all species. Food web magnification factors (FWMFs) were determined for the OCs by using trophic levels determined from delta(15)N. FWMFs >1, indicating biomagnification, were found for Sigma PCB, penta- or higher chlorinated PCBs (e.g., PCB 101, 118, 138, 153, 180), beta-HCH, HCB, Sigma DDT, p,p-DDE, and transnonachlor. The highest FWMF was observed for PCB 180 at FWMF = 5.8.

Genotoxicity of environmentally relevant concentrations of water-soluble oil components in cod (Gadus morhua).

Large discharges from oil and gas production platforms (produced water) have led to concerns for adverse biological effects in marine areas. The aim of this study was to investigate the development of DNA adductformation and related biomarkers in fish after chronic exposure to water-soluble components of oil. Atlantic cod (Gadus morhua) were exposed for up to 44 weeks to three treatments (low, pulsed, high) containing environmentally relevant concentrations of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs) and short-chained alkylphenols (APs). A time- and dose-related pattern of DNA adduct formation (measured using 32P-postlabeling) was observed. The results suggested that an extended exposure period (more than 16 weeks) would be required for the formation of DNA adduct levels above background. Interestingly, fish receiving pulsed high exposure did not develop elevated concentrations of DNA adducts, possibly due to DNA repair processes. No obvious relationship between DNA adduct concentration and cytochrome P4501A activity (EROD) was observed. This study has demonstrated the genotoxic potential of water-soluble oil components, relevant for operational discharges (produced water) and chronic oil spills. The quantification of PAH metabolites in bile and hepatic DNA adduct formation appear to be suitable for environmental monitoring of chronic oil pollution.

DNA adducts and polycyclic aromatic hydrocarbon (PAH) tissue levels in blue mussels (Mytilus spp.) from Nordic coastal sites.

DNA adducts in gills and digestive gland, as well as polycyclic aromatic hydrocarbon (PAH) tissue levels were analysed in blue mussels (Mytilus spp.) from Nordic coastal areas (Iceland, Norway and Sweden) with diffuse or point sources of PAHs of various origins. Both DNA adduct and PAH tissue levels were generally low, indicating low PAH exposure to the mussels in the areas studied. DNA adducts were found to be higher in gills than in digestive gland of the mussels at all sites studied. Elevated DNA adduct levels in gills were found at 6 sites out of 18 compared to reference sites in respective coastal zones. Adduct levels ranged from 0.5 to 10 nmol adducts/mol normal nucleotides, being highest in mussels from Reykjavík harbour, Iceland (intertidal mussels), and from Fiskaatangen, Norway (subtidal mussels). Total PAH tissue levels in the mussels ranged between 40 and 11,670 ng/g dry wt., and were significantly correlated with DNA adduct levels (r(2)=0.73, p<0.001). PAH ratio values indicated that the PAHs were in most cases of pyrolytic origin, but with petrogenic input near harbours and an oil refinery.

Seasonal and intertidal impact on DNA adduct levels in gills of blue mussels (Mytilus edulis L.).

The aim of this study was to elucidate possible seasonal variation in DNA adduct levels in blue mussels (Mytilus edulis), and to investigate the impact of intertidal exposure on the DNA adduct levels, i.e. to explore if DNA adduct levels in mussels in the intertidal zone differ from those in the subtidal zone. Blue mussels were deployed separately in the intertidal and subtidal zone at a contaminated and a reference site in Iceland, and sampled regularly during one year. Gill DNA adduct levels were found to be higher in mussels in the intertidal zone compared to the subtidal zone at the contaminated site, the difference being largest in winter. Total PAH tissue levels were also higher in mussels in the intertidal zone. Seasonal variation was observed in both DNA adduct and PAH tissue levels in mussels at the contaminated site, with lower levels from the time of transplantation in summer to autumn, maximum levels in winter, which decreased to lower levels again in spring and summer the following year. DNA adducts and PAH levels were low or below the detection limits in mussels at the reference site at all times, both in the intertidal and subtidal zone.