Sammendrag
Oxidative stress occurs when there is an imbalance between
the production of reactive oxygen species (ROS) and antioxidant defense.
Exposure to pollutants may increase ROS and affect antioxidant levels, and
the resulting oxidative stress may negatively affect both reproduction and
survival. We measured concentrations of 18 persistent organic pollutants
(POPs) and 9 toxic elements in blood, as well as total antioxidant capacity
(TAC), total glutathione (tGSH), and carotenoids in plasma of Baltic and
Arctic female common eiders (Somateria mollissima) (N = 54) at the end
of their incubation-related fasting. The more polluted Baltic population
had higher TAC and tGSH concentrations compared to the Arctic
population. Carotenoid levels did not differ between populations. The
effect of mixtures of pollutants on the antioxidants was assessed, and the
summed molar blood concentrations of 14 POPs were positively related to TAC. There was no significant relationship between
the analyzed pollutants and tGSH concentrations. The adaptive improvement of the antioxidant defense system in the Baltic
population may be a consequence of increased oxidative stress. However, both increased oxidative stress and energy allocation
toward antioxidant defense may have adverse consequences for Baltic eiders at the incubation stage, when energy resources reach
an annual minimum due to incubation-related fasting.
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