Plasma carotenoid depletion during fasting in moulting penguins

The questions of whether carotenoids are mobilized from storage organs or the blood during food shortages or in stressful situations and the amount of carotenoids available in these situations remain contentious. We study the amount of carotenoids circulating in the blood stream in Gentoo Penguins (Pygoscelis papua), taking advantage of the physiological stress produced by fasting during moulting. Carotenoids are not detectable in the blood after 1 week of fasting during moulting in Gentoo Penguins, whereas breeding adults and chicks show a high concentration of astaxanthin. Our results suggest that carotenoids are consumed in physiologically stressful processes other than ornamentation.