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Jasmine Nahrgang - One of the best experts on this subject based on the ideXlab platform.

  • Morphology, Transcriptomics and In Vitro Model of Skin from Polar Cod (Boreogadus saida) and Atlantic Cod (Gadus Morhua)
    Fishes, 2020
    Co-Authors: Elisabeth Ytteborg, Ireen Vieweg, Jasmine Nahrgang, Øyvind Johannes Hansen, Vibeke Høst, Sergey Afanasyev, Aleksei Krasnov
    Abstract:

    Fish skin is a multifunctional barrier tissue with high regeneration capacity that interacts with the surrounding environment and provides protection. Functional importance, high complexity and activity make skin an attractive tissue for studying the effects of environmental challenges and chemical stressors in fish. The aim of this work was to characterize skin from polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua), and to test cod skin as an in vitro model in exposure studies. Both species have similar skin structures including epidermis, mucous cells, club cells and scales. However, microarchitectural differences were detected; Atlantic cod has a smooth epidermal surface and overlapping scales, whereas polar cod has a folded outer surface and discontinuous scales. Genome-wide microarray found 6.5k genes with expression differences, which suggested more active turnover of proteins, proliferation and motility of cells in skin of polar cod. Hydrogen peroxide (H2O2) was used to examine skin responses. Transcriptome response was stronger in the skin of polar cod, with 155 differentially expressed genes. The skin from Atlantic cod was further used to develop a cell culture. H2O2 decreased the cell migration rate in a dose-dependent manner, which could indicate reduced skin healing capacity. The results revealed novel skin structures and confirmed that the skin from cod is a promising tissue for evaluation of stressors.

  • Effects of acute exposure to dispersed oil and burned oil residue on long-term survival, growth, and reproductive development in polar cod (Boreogadus saida).
    Marine environmental research, 2018
    Co-Authors: Morgan Lizabeth Bender, Lionel Camus, Marianne Frantzen, S. Le Floch, J. Palerud, Jasmine Nahrgang
    Abstract:

    Abstract The present study investigates the potential long-term physiological effects on maturing polar cod (Boreogadus saida), an Arctic key species, after an acute exposure (48 h) to environmentally realistic concentrations of either mechanically dispersed oil (MDO), chemically dispersed oil (CDO) or burned oil residues (BO) (N = 58–60 per treatment). Following exposure, fish were monitored in a common tank supplied with clean water for a seven-month period coinciding with the period of reproductive development. Females exposed to BO residues were more frequently found in an earlier phase of gonadal maturation compared to unexposed females while no effects of different oil spill response (OSR) actions were seen in the reproductive development of males. Mechanically and chemically dispersed oil induced a transient short-term reduction in growth in the first week post-exposure. Overall, no significant long-term effects of exposure were seen in growth or mortality. Ultimately, this study provides information for the assessment of population consequences of different OSR actions as part of a net environmental benefit analysis.

  • Antioxidant defenses in polar cod (Boreogadus saida) and responsiveness toward dietary crude oil exposure
    Marine environmental research, 2017
    Co-Authors: Ireen Vieweg, Maura Benedetti, Ilaria Lanzoni, Francesco Regoli, Jasmine Nahrgang
    Abstract:

    Increasing anthropogenic activities in the Arctic pose the risk for accidental oil spills but our knowledge of ecotoxicological effects is still limited for Arctic organisms. This study aimed to provide insights in baseline levels of antioxidants in polar cod (Boreogadus saida) from different Arctic locations and investigate the susceptibility of this species to oxidative stress during a 32 day dietary crude oil exposure. Baseline levels of individual antioxidants and total oxyradical scavenging capacity (TOSC) varied among different Arctic fjords. Upon crude oil exposure, dose- and time-dependent polycyclic aromatic hydrocarbons (PAHs) biotransformation was evident through hepatic ethoxyresorufine-O-deethylase activity, glutathione S-transferase mRNA expression and biliary PAH metabolites. Changes in the activity of individual antioxidants and TOSC was, however, slight and transient upon exposure. In conclusion, biotransformation was clearly induced by the sub-lethal levels of crude oil in polar cod, while the antioxidant defense responded with high variability.

  • early life stages of an arctic keystone species Boreogadus saida show high sensitivity to a water soluble fraction of crude oil
    Environmental Pollution, 2016
    Co-Authors: Jasmine Nahrgang, Marianne Frantzen, Paul Dubourg, Daniela Storch, Flemming Dahlke, James P Meador
    Abstract:

    Increasing anthropogenic activities in the Arctic represent an enhanced threat for oil pollution in a marine environment that is already at risk from climate warming. In particular, this applies to species with free-living pelagic larvae that aggregate in surface waters and under the sea ice where hydrocarbons are likely to remain for extended periods of time due to low temperatures. We exposed the positively buoyant eggs of polar cod (Boreogadus saida), an arctic keystone species, to realistic concentrations of a crude oil water-soluble fraction (WSF), mimicking exposure of eggs aggregating under the ice to oil WSF leaking from brine channels following encapsulation in ice. Total hydrocarbon and polycyclic aromatic hydrocarbon levels were in the ng/L range, with most exposure concentrations below the limits of detection throughout the experiment for all treatments. The proportion of viable, free-swimming larvae decreased significantly with dose and showed increases in the incidence and severity of spine curvature, yolk sac alterations and a reduction in spine length. These effects are expected to compromise the motility, feeding capacity, and predator avoidance during critical early life stages for this important species. Our results imply that the viability and fitness of polar cod early life stages is significantly reduced when exposed to extremely low and environmentally realistic levels of aqueous hydrocarbons, which may have important implications for arctic food web dynamics and ecosystem functioning.

  • Effects of chronic dietary petroleum exposure on reproductive development in polar cod (Boreogadus saida)
    Aquatic toxicology (Amsterdam Netherlands), 2016
    Co-Authors: Morgan Lizabeth Bender, Ireen Vieweg, Marianne Frantzen, Inger-britt Falk-petersen, H. K. Johnsen, Geir Rudolfsen, Knut Erik Tollefsen, Paul Dubourg, Jasmine Nahrgang
    Abstract:

    Abstract Increasing human activities in the Arctic raise the risk of petroleum pollution, thus posing an elevated risk for Arctic organisms to be chronically exposed to petroleum compounds. The endocrine disrupting properties of some of these compounds (i.e. polycyclic aromatic hydrocarbons [PAHs]) present in crude oil may have negative effects on the long and energy intensive reproductive development of polar cod (Boreogadus saida), an Arctic keystone species. In the present study, selected reproductive parameters were examined in feral polar cod exposed to crude oil via a natural diet (0.11, 0.57 and 1.14 μg crude oil/g fish/day [corresponding to low, medium and high treatments, respectively]) for 31 weeks prior to spawning. Fish maturing in the current reproductive period made up 92% of the experimental population while 5% were immature and 3% were identified as resting fish. Phase I metabolism of PAHs, indicated by ethoxyresorufin-O-deethylase (EROD) activity, showed a dose-dependent increase in high and medium crude oil treatments at week 6 and 22, respectively. Decreasing EROD activity and increasing PAH bile metabolite concentrations over the experimental period may be explained by reproductive maturity stage. Significant alterations in sperm motility were observed in crude oil exposed males compared to the controls. The investigated somatic indices (gonad and hepatic), germ cell development and plasma steroid levels (estradiol-17β [females], testosterone [males and females] and 11-ketotestosterone [males]) were not significantly altered by chronic dietary exposure to crude oil. The environmentally realistic doses polar cod were chronically exposed to in this study were likely not high enough to induce adverse effects in this ecologically important fish species. This study elucidated many baseline aspects of polar cod reproductive physiology and emphasized the influence of maturation state on biomarkers of PAH biotransformation (EROD and PAH bile metabolites).

Louis Fortier - One of the best experts on this subject based on the ideXlab platform.

  • Pelagic production and the recruitment of juvenile polar cod Boreogadus saida in Canadian Arctic seas
    Polar Biology, 2019
    Co-Authors: Mathieu Leblanc, Maxime Geoffroy, Andrew Majewski, Caroline Bouchard, Stephane Gauthier, James D Reist, Louis Fortier
    Abstract:

    Previous work found that an earlier ice breakup favors the recruitment of juvenile polar cod ( Boreogadus saida ) by enabling early hatchers to survive and reach a large size by late summer thanks to a long growth season. We tested the hypothesis that, in addition to a long growth season, an earlier ice breakup provides superior feeding conditions for young polar cod by enhancing microalgal and zooplankton production over the summer months. Ice cover and surface chlorophyll a were derived from satellite observations, and zooplankton and juvenile cod biomass were estimated by hydroacoustics in ten regions of the Canadian Arctic over a period of 11 years. Earlier breakups resulted in earlier phytoplankton blooms. Zooplankton backscatter in August increased with earlier breakup and bloom, and plateaued at chlorophyll a  > 1 mg m^−3. Juvenile cod biomass in August increased with an earlier breakup, and plateaued at a zooplankton backscatter > 5 m^2 nmi^−2, supporting the hypothesis that higher food availability promotes the growth and survival of age-0 fish in years of early ice melt. However, there was little evidence that late summer biomass of either zooplankton or age-0 polar cod benefitted from ice breakup occurring prior to June. On average, zooplankton standing stock was similar in the Southern Beaufort Sea and the North Water-Lancaster Sound polynya complex, but juvenile cod biomass was higher in the Beaufort Sea. Intense avian predation could explain the lower biomass of juvenile cod in the polynya complex, confirming its reputation as a biological hotspot for energy transfer to higher trophic levels.

  • Contrasting the early life histories of sympatric Arctic gadids Boreogadus saida and Arctogadus glacialis in the Canadian Beaufort Sea
    Polar Biology, 2016
    Co-Authors: Caroline Bouchard, Dominique Robert, Salomé Mollard, Keita Suzuki, Louis Fortier
    Abstract:

    The early life stages of Boreogadus saida and Arctogadus glacialis are morphologically similar, making it difficult to assess differences in their ecological niche. The present study documented for the first time the early life stage ecology of A. glacialis , compared it to that of B. saida , and identified the factors separating the niches of the two sympatric species. The 10,565 larval gadids collected in the Beaufort Sea from April to August of 2004 and 2008 were identified to species either directly by genetics and/or otolith nucleus size, or indirectly with a redistribution procedure. Between 8.0 and 8.7 % of all gadids were assigned to A. glacialis . Larvae of A. glacialis were longer at hatch and experienced lower mortality rates than those of B. saida . The two species shared similar spatiotemporal and vertical distributions, hatching season, and growth rate. Under the ice, feeding incidence of B. saida was low (14 %) relative to A. glacialis (88 %). At lengths 15 mm overlapped (Schoener’s index = 0.7), with Calanus glacialis and C. hyperboreus providing >50 % of the carbon intake of both species. The higher mortality in B. saida may be explained by the smaller size at age from hatching to metamorphosis and a lower under-ice feeding incidence. The early larval stage appears to be the key period of niche divergence between the two species.

  • Vertical segregation of age-0 and age-1+ polar cod (Boreogadus saida) over the annual cycle in the Canadian Beaufort Sea
    Polar Biology, 2015
    Co-Authors: Maxime Geoffroy, Mathieu Leblanc, Andrew Majewski, Stephane Gauthier, James D Reist, Wojciech Walkusz, Louis Fortier
    Abstract:

    The offshore marine ecosystem of the Canadian Beaufort Sea faces the double pressure of climate change and industrialization. Polar cod (Boreogadus saida) is a pivotal forage species in this ecosystem, accounting for 95 % of the pelagic fish assemblage. Its vertical distribution over the annual cycle remains poorly documented. Hydroacoustic records from 2006 to 2012 were analysed to test the hypothesis that age-0 polar cod segregate vertically from larger congeners. Trawls and ichthyoplankton nets validated the acoustic signal. Fish length, weight, and biomass were estimated from new regressions of target strength and weight on standard length. Polar cod were vertically segregated by size in all months, with small age-0 juveniles in the epipelagic (

  • Spatial segregation, dispersion and migration in early stages of polar cod Boreogadus saida revealed by otolith chemistry
    Marine Biology, 2015
    Co-Authors: Caroline Bouchard, Simon R. Thorrold, Louis Fortier
    Abstract:

    Arctic marine food webs are centered on polar cod (Boreogadus saida), a small, largely pelagic gadid, which movement and migration remain unclear, especially for the early life stages. The present study examined the otolith chemistry of juvenile polar cod from six oceanographic regions of the Arctic Ocean in order to document patterns of spatial segregation, dispersion and migration during the species early life. The freshwater winter refuge hypothesis, suggesting that polar cod larvae start to hatch in winter in freshwater-influenced regions but only later in the season in purely marine regions, was also tested. Five elemental ratios (Li/Ca, Mg/Ca, Mn/Ca, Sr/Ca and Ba/Ca) were analyzed by laser ablation inductively coupled plasma mass spectrometry in three otolith zones representing the egg, larval and juvenile stages. The concentration of each of the five elements at the edge of the otoliths, corresponding to incorporation shortly before capture, was significantly correlated with surface salinity and temperature at capture site and date. Otolith chemistry differed between juveniles from freshwater-influenced regions (Laptev Sea, Hudson Bay Amundsen Gulf) and those from purely marine regions (Lancaster Sound, Baffin Bay, Frobisher Bay), in agreement with dissolved concentrations of at least some of the target elements in the Arctic Ocean. Discriminant function analyses including all five elements provided valuable information on the species population structure and dispersion of early stages. The correspondence between otolith Mn/Ca, Ba/Ca and vertical profiles of dissolved Mn and Ba in the water column may reflect the ontogenetic vertical migration of juvenile polar cod in late-summer and fall.

  • The nucleus of the lapillar otolith discriminates the early life stages of Boreogadus saida and Arctogadus glacialis
    Polar Biology, 2013
    Co-Authors: Caroline Bouchard, R. J. Nelson, Dominique Robert, Louis Fortier
    Abstract:

    Polar cod ( Boreogadus saida ) and ice cod ( Arctogadus glacialis ) are sympatric on continental shelves of the Arctic Ocean. The larvae and early juveniles of the two species are similar, and discrimination based on morphology and pigmentation is uncertain. We present a discrimination criterion based on the difference in lapillus nucleus size between genetically identified B. saida ( n  = 441, 4.2–55.0 mm standard length) and A . glacialis ( n  = 82, 8.6–45.5 mm). The product of the shortest and longest diameters of the nucleus (SN × LN) was 58 % larger in A . glacialis than in B . saida . The logistic regression (Ln[ p /(1 −  p )] = 0.02687SN × LN − 17.5466), where p is the probability that the fish is A . glacialis , correctly reassigned 501 of the 523 fishes (96 %) used to build the model to their genetically determined species (99 % of B . saida and 80 % of A . glacialis ). The same regression correctly classified 97 % of 189 fish sampled in 2002 and 2003 and not used in building the model (99 % of B . saida and 89 % of A . glacialis ).

Terry A. Dick - One of the best experts on this subject based on the ideXlab platform.

  • First documented large-scale horizontal movements of individual Arctic cod (Boreogadus saida)
    Canadian Journal of Fisheries and Aquatic Sciences, 2017
    Co-Authors: Steven T. Kessel, Nigel E. Hussey, Richard E. Crawford, David J. Yurkowski, Dale M. Webber, Terry A. Dick, Aaron T. Fisk
    Abstract:

    Arctic cod (Boreogadus saida) are a key component of the Arctic marine ecosystem. Understanding their movements and distribution is important for predicting future trends in response to climate change. It was commonly assumed that Arctic cod move horizontally throughout the Arctic, but this was so far unproven. In July 2012, 85 Arctic cod were implanted with acoustic transmitters at Resolute Bay, Nunavut, Canada. Five (5.9%) were subsequently detected ∼192 km due east along the Barrow Strait, between 67 and 215 days after last detection in Resolute Bay (mean ± SE = 161.4 ± 26.7 days). Minimum transition rates ranged between 0.89 and 2.87 km·day−1 (mean ± SE = 1.4 ± 0.4 km·day−1). A combination of factors, most notably sea ice extent, make it highly improbable that the detections were representative of predated or scavenged Arctic cod. This represents the first confirmed account of large-scale horizontal movements by this or any Arctic forage fish species. With continuing miniaturization of acoustic teleme...

  • The foraging ecology of Arctic cod ( Boreogadus saida ) during open water (July–August) in Allen Bay, Arctic Canada
    Marine Biology, 2013
    Co-Authors: Jordan K. Matley, Aaron T. Fisk, Terry A. Dick
    Abstract:

    Arctic cod (Boreogadus saida) is a schooling fish providing a critical link between lower and upper trophic levels in the Arctic. This study examined foraging of Arctic cod collected from Allen Bay, Cornwallis Island, Canada (~75 N 95 W), during summer 2010 using temporal indicators of diet including stomach content, and carbon (δ13C) and nitrogen (δ15N) stable isotopes of liver and muscle. Foraging at the time of capture reflected sympagic and epi-benthic habitats indicated by the prevalence of cyclopoid and harpacticoid copepods in stomachs, whereas stable isotope data, which provide an estimate of feeding over a longer period, indicated pelagic prey as important. Prey selection of juveniles differed from adults based on stable isotopes, while large adults showed the most separation based on stomach contents, suggesting size-related diet shifts. Compared to studies near Resolute in the 1970s, 1980s, and 1990s, growth and pre-spawning gonadal conditions of Arctic cod have not changed.

  • the foraging ecology of arctic cod Boreogadus saida during open water july august in allen bay arctic canada
    Marine Biology, 2013
    Co-Authors: Jordan K. Matley, Aaron T. Fisk, Terry A. Dick
    Abstract:

    Arctic cod (Boreogadus saida) is a schooling fish providing a critical link between lower and upper trophic levels in the Arctic. This study examined foraging of Arctic cod collected from Allen Bay, Cornwallis Island, Canada (~75 N 95 W), during summer 2010 using temporal indicators of diet including stomach content, and carbon (δ13C) and nitrogen (δ15N) stable isotopes of liver and muscle. Foraging at the time of capture reflected sympagic and epi-benthic habitats indicated by the prevalence of cyclopoid and harpacticoid copepods in stomachs, whereas stable isotope data, which provide an estimate of feeding over a longer period, indicated pelagic prey as important. Prey selection of juveniles differed from adults based on stable isotopes, while large adults showed the most separation based on stomach contents, suggesting size-related diet shifts. Compared to studies near Resolute in the 1970s, 1980s, and 1990s, growth and pre-spawning gonadal conditions of Arctic cod have not changed.

  • Summer foraging behaviour of shallow-diving seabirds and distribution of their prey, Arctic cod ( Boreogadus saida ), in the Canadian Arctic
    Polar Research, 2012
    Co-Authors: Jordan K. Matley, Richard E. Crawford, Terry A. Dick
    Abstract:

    Productive areas in the Canadian Arctic seasonally provide top predators with accessible and often predictable sources of energy. Arctic cod ( Boreogadus saida ) aggregate in shallow bays during the summer and are exploited by seabirds and marine mammals. Information concerning how prey is presented to predatory seabirds, and the cues seabirds use to optimize foraging potential, is limited. Hydroacoustic surveys were completed in Allen Bay, Nunavut, to determine the presence, density, abundance, and depth of Arctic cod schools in relation to shallow-diving seabirds. Schools were also documented using standardized protocols to examine the influence of environmental variables, such as wind, ice, tidal states and seabird behaviour. The presence of schools was a significant predictor of the distribution of northern fulmars ( Fulmarus glacialis ) but not black-legged kittiwakes ( Rissa tridactyla ). Glaucous gulls ( Larus hyperboreus ) associated with northern fulmars are likely optimizing chances of stealing Arctic cod. The density, size and depth of schools did not significantly affect the distribution of the seabirds. We speculate that Arctic cod from demersal schools separate to feed at the surface in satellite schools (groups of dispersed fish), thus reducing competition but increasing the risk of predation. Keywords: Satellite schools; schooling; predators; northern fulmar; black-legged kittiwake; glaucous gull (Published: 3 September 2012) Citation: Polar Research 2012, 31, 15894, http://dx.doi.org/10.3402/polar.v31i0.15894

  • Observation of common raven ( Corvus corax ) scavenging Arctic cod ( Boreogadus saida ) from seabirds in the Canadian High Arctic
    Polar Biology, 2012
    Co-Authors: Jordan K. Matley, Richard E. Crawford, Terry A. Dick
    Abstract:

    The common raven (Corvus corax) is one of the most intelligent avian species, known for its ability to scavenge from humans and other animals. This adaptive nature is critical in habitats where food can be scarce. The Arctic is such an environment, and optimizing associations with sources of prey is important. Large aggregations of Arctic cod (Boreogadus saida) in shallow waters provide a high energetic source for top predators such as seabirds and marine mammals, and consequently potential food sources for ravens. We document, to our knowledge, the first observations of a raven feeding on Arctic cod discarded by seabirds. This report supplements knowledge of ravens to opportunistically meet dietary requirements and the importance of Arctic cod to avian ecology in the Arctic.

David G Barber - One of the best experts on this subject based on the ideXlab platform.

Haakon Hop - One of the best experts on this subject based on the ideXlab platform.

  • Trophic ecology of sympatric Arctic gadoids, Arctogadus glacialis (Peters, 1872) and Boreogadus saida (Lepechin, 1774), in NE Greenland
    Polar Biology, 2012
    Co-Authors: Jørgen S. Christiansen, Haakon Hop, Einar M. Nilssen, John Joensen
    Abstract:

    Two gadoid fishes, Arctogadus glacialis and Boreogadus saida, often coexist (i.e. sympatric) in the fjords and shelf areas of the Arctic seas, where they likely share the same food resources. Diet composition from stomach contents, i.e. frequency of occurrence (FO) and Schoener’s index (SI), and stable isotope signatures (δ13C and δ15N) in muscle of these sympatric gadoids were examined from two fjords in NE Greenland—Tyrolerfjord (TF, ~74oN, sill present) and Dove Bugt (DB, ~76oN, open). Twenty-three prey taxa and categories were identified and both gadoids ate mostly crustaceans. The SI values of 0.64–0.70 indicated possible resource competition, whereas FO differed significantly. A. glacialis fed mainly on the mysid Mysis oculata and other benthic-associated prey, whereas B. saida ate the copepod Metridia longa and other pelagic prey. Both diet and stable isotopes strongly suggest a spatial segregation in feeding habitat, with A. glacialis being associated with the benthic food web (mean δ13C = −20.81‰, δ15N = 14.92‰) and B. saida with the pelagic food web (mean δ13C = −21.25‰, δ15N = 13.64‰). The dietary differences and isotopic signals were highly significant in the secluded TF and less clear in the open DB, where prey and predators may be readily advected from adjacent areas with other trophic conditions. This is the first study on the trophic position of A.glacialis inferred from analyses of stable isotopes. The subtle interaction between the Arctic gadoids should be carefully monitored in the light of ocean warming and on-going invasions of boreal fishes into the Arctic seas.

  • Seasonal baseline levels of physiological and biochemical parameters in polar cod (Boreogadus saida): Implications for environmental monitoring
    Marine pollution bulletin, 2010
    Co-Authors: Jasmine Nahrgang, Lionel Camus, Jørgen S. Christiansen, Fredrik Broms, Haakon Hop
    Abstract:

    Seasonality of biomarker baseline levels were studied in polar cod (Boreogadus saida), caught in Kongsfjorden, Svalbard, in April, July, September and December, 2006-2007. Physiological parameters (condition factor, gonado- and hepato-somatic indexes, energy reserves, potential metabolic activity and antifreeze activity) in polar cod were used to interpret the seasonality of potential biomarkers. The highest levels of ethoxyresorufin-O-deethylase (EROD) activity occurred concomitantly with the highest potential metabolic activity in July due to e.g. intense feeding. During pre-spawning, EROD showed significant inhibition and gender differences. Hence, its potential use in environmental monitoring should imply gender differentiation at least during this period. Glutathione S-transferase and catalase activities were stable from April to September, but changed in December suggesting a link to low biological activity. Knowledge of the biomarker baseline levels and their seasonal trends in polar cod is essential for a trustworthy interpretation of forthcoming toxicity data and environmental monitoring in the Arctic.

  • Biomarker responses in polar cod (Boreogadus saida) exposed to the water soluble fraction of crude oil.
    Aquatic toxicology (Amsterdam Netherlands), 2009
    Co-Authors: Jasmine Nahrgang, Lionel Camus, Jørgen S. Christiansen, Patrice Gonzalez, Martina Jönsson, Mark G. Carls, Ingrid Christina Taban, Renée Katrin Bechmann, Haakon Hop
    Abstract:

    Abstract In order to mimic the biological effects of an oil spill in Arctic waters, we examined several types of biomarkers (genes, enzymes, metabolites, and DNA damage) in polar cod Boreogadus saida experimentally exposed to the water soluble fractions of crude oil. During 4 weeks of exposure, induction of the studied biomarkers exceeded baseline levels. The mRNA expression of the cytochrome P4501A1 ( cyp1a1 ) gene was the most promising biomarker, with glutathione S-transferase ( gst ) as a suitable complement. The delayed ethoxyresorufin O-deethylase (EROD) and GST activities and their persistence following 2 weeks of depuration may allow detection of previous exposures in field samples. The composition of PAH metabolites in the bile indicated the bioavailability of different PAH size-classes. Although mRNA expressions of antioxidant defense genes were induced at start of the exposure, with the strongest responses from catalase and cytosolic superoxide dismutase, they were poor for oil monitoring purposes due to their very short response times. Significant DNA damage demonstrated genotoxicity even at low PAH concentrations ( −1 ) and was correlated with benzo(a)pyrene and pyrene metabolites in the bile.

  • Biomarker responses in polar cod (Boreogadus saida) exposed to dietary crude oil.
    Aquatic toxicology (Amsterdam Netherlands), 2009
    Co-Authors: Jasmine Nahrgang, Lionel Camus, Jørgen S. Christiansen, Patrice Gonzalez, Martina Jönsson, Haakon Hop
    Abstract:

    Abstract Polar cod Boreogadus saida were exposed weekly to two doses of dietary crude oil for 4 weeks followed by 2 weeks of depuration. Administered doses corresponded on average to 4 and 9 μg ΣPAHs g −1  fish week −1 . Cytochrome P4501A1 ( cyp1a1 ) and glutathione S -transferase ( gst ) mRNA expression, ethoxyresorufin O-deethylase (EROD) activity and metabolites in the bile showed strong and dose-dependent inductions at 2 and 4 weeks of exposure. Following 2 weeks depuration, mRNA expression of cyp1a1 and gst and PAH metabolites returned to basal levels while EROD activity and GST activity were still induced in the high oil treatment. The mRNA expressions of antioxidant defense genes (catalase, glutathione peroxidase and cytosolic and mitochondrial superoxide dismutase) did not change significantly during the experiment. Catalase activity was significantly depressed at week 2 in the high oil treatment. We conclude that the cyp1a1 mRNA expression, EROD activities and bile metabolites were the most reliable biomarkers of exposure while gst mRNA expression and GST activity were less sensitive and are considered only as complementary. Antioxidant defenses were poor biomarkers to assess effects of crude oil exposure in polar cod.

  • PAH biomarker responses in polar cod (Boreogadus saida) exposed to benzo(a)pyrene.
    Aquatic toxicology (Amsterdam Netherlands), 2009
    Co-Authors: Jasmine Nahrgang, Lionel Camus, Jørgen S. Christiansen, Patrice Gonzalez, Anders Goksøyr, Haakon Hop
    Abstract:

    With expanding oil and gas activities into the Arctic region, there is a need to evaluate the induction capacity of polycyclic aromatic hydrocarbon (PAH) biomarkers on Arctic marine organisms and to test analytical methods that have been optimized for their temperate counterparts. Polar cod Boreogadus saida were injected intraperitoneally with cod liver oil (solvent control), 6.6+/-3.7, 85+/-48 or 378+/-190 microg kg(-1) wet weight of benzo(a)pyrene (B(a)P), or not injected (control), and liver and bile were sampled at 0 and 16 h and 1, 2, 4 and 7d. The mRNA expression of cytochrome P4501A1 (cyp1a1) and glutathione S-transferase (gst) genes showed a dose-dependent induction in the first 16 h following the injection and a return to basal levels after 4d. The aryl hydrocarbon receptor 2, however, showed no change in mRNA expression. The protein quantification of cytochrome P4501A (CYP1A), through Western blot analysis and the enzyme-linked immunosorbent assay (ELISA), presented similar but weaker and time-delayed responses (4-7d) compared to the gene (16 h to 2d). Ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities increased significantly at day 7 following the gene induction and increase in protein levels. Overall, these biomarkers showed dose-dependent but weak responses to B(a)P and low levels of bile metabolites. The mRNA expressions of oxidative stress genes, superoxide dismutases (sod(Cu/Zn) and sod(Mn)), catalase (cat) and glutathione peroxidase (gpx), were all up-regulated between 16 h and 2d of B(a)P exposure with cat (72-fold) and sod(Cu/Zn) (20-fold) giving the strongest responses in the highest dose. Finally, CAT protein level and enzyme activities showed less clear responses than the genes. The mRNA expression showed the earliest responses, followed by the protein levels. The enzymatic activities were the least sensitive and responded to the exposure after 7d. The study shows the induction capability of biomarkers in polar cod at very low bioavailable doses of B(a)P and provides new information on the selected biomarkers for use in oil monitoring in the Arctic.