PhD defence: Jasmine Nahrgang

Jasmine Nahrgang succesfully defended her dissertation: Biomarker responses in polar cod (Boreogadus saida) - Application for petroleum monitoring in Arctic waters.

Jasmine Nahrgang has carried out a PhD from 2006-2009 at Akvaplan-niva and University of Tromsø to study the “Biomarker responses in polar cod (Boreogadus saida), Application for petroleum monitoring in Arctic waters”.

The project led by Akvaplan-niva involved several partners: The University of Tromsø, The Norwegian Polar Institute, Norwegian Institute for Water Research, Murmansk Marine Biological Institute, Karelian Research Center, NOAA Alaska Fisheries Science Center Auke Bay Laboratory, International Research Institute of Stavanger.

The project was financed by ConocoPhillips Norge. The supervisors were Dr Lionel Camus (Akvaplan-.niva/University Centre on Svalbard), Dr. Jørgen Schou Christiansen (Tromsø University) and Haakon Hop (Norwegian Polar Institute).

The disputation was held 23 january 2010. Professor Francesco Regoli from Politecnica delle Marche, Ancona, Italy, and professor Angela Köhler from Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany, were opponents, and professor Even Jørgensen from our faculty was member of the committee. Head of The Norwegian College of Fishery Science Jan-Eirik Angell Killie managed the disputation.

Contact details

Nahrgang works at Akvaplan-niva in Tromsø. Phone 77750371. E-mail: jn@akvaplan.niva.no

Abstract

Oil and gas activities are expanding to the Arctic shelf Seas and bring along an important concern about accidental petroleum discharges to Arctic ecosystems. In this context, environmental monitoring programmes need to be implemented in the Arctic, with appropriate monitoring tools, so-called “biomarkers”, adapted to Arctic species. Biomarkers are commonly used for temperate species such as Atlantic cod but cannot be directly applied to cold water species due to biological differences. Hence, the goal of this Thesis was to test some well known biomarkers on the polar cod Boreogadus saida, a small circumpolar fish that has been selected as an indicator species for environmental monitoring in the Arctic.

A field study and three laboratory experiments allowed studying the baseline levels, seasonality and responsiveness to oil compounds of the cytochrome P4501A (CYP1A), the glutathione S-transferase (GST) and PAH metabolites in the bile as PAH exposure biomarkers, antioxidant enzymes (catalase, glutathione peroxidase and superoxide dismutase) as oxidative stress biomarkers, DNA damage with the comet assay as a biomarker of genotoxicity and whole body respiration as a physiological biomarker of metabolic rate.

The strong seasonality in food availability in Arctic environments between summer and winter as well as the natural biological cycle of organisms affects their physiology and consequently the baseline levels of biomarkers in wild, uncontaminated polar cod. For instance, CYP1A varies between summer and winter due to changes in the polar cod’s biological activity (feeding, motility, etc.) and gender differences occurred during the reproductive season in December. In laboratory experiments where polar cod were exposed to a single PAH compound or to crude oil via the water or via the food, CYP1A, GST and PAH metabolites showed strong dose-dependent inductions and were considered as relevant biomarkers. By contrast, the lack of dose-dependency and the premature and transient responses of the antioxidant defences inferred that these biomarkers were inappropriate for detection of PAH exposure.

To conclude, this Thesis provided (i) some insights to the general eco-physiological responses of polar cod to natural processes during periods of e.g. reproduction and feeding and to PAH exposure, (ii) a range of baseline values of the selected biomarkers and their seasonal amplitude for sound interpretation of field-based toxicity assessments and (iii) a “toolbox” i.e. a suite of biomarkers with immediate application in the development of Arctic environmental monitoring and risk assessment programmes.

Last Updated (Thursday, 22 April 2010 12:37)

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