Diel pattern of corticosterone metabolites in Arctic barnacle goslings (Branta leucopsis) under continuous natural light

• Published in: PloS one Vol. 12; no. 8; p. e0182861
• Main Authors: Scheiber, Isabella B R, de Jong, Margje E, Komdeur, Jan, Pschernig, Elisabeth, Loonen, Maarten J J E, Millesi, Eva, Weiß, Brigitte M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.08.2017; Public Library of Science (PLoS)
• Subjects: Animal behavior; Animals; Anseriformes - metabolism; Anseriformes - physiology; Aquatic birds; Arctic Regions; Biology and Life Sciences; Circadian Rhythm; Circularity; Continuity (mathematics); Corticosterone; Corticosterone - metabolism; Ecology; Ecology and Environmental Sciences; Entrainment; Environmental factors; Enzyme immunoassay; Excretion; Geese; Herbivores; Hormones; Immunoassay; Juveniles; Life sciences; Light; Medicine and Health Sciences; Melatonin; Metabolism; Metabolites; Physiological aspects; Physiology; Polar environments; Polar regions; Research and Analysis Methods; Stress response; Time measurement; Wildfowl; Zeitgeber; Arctic region
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0182861

Here we describe the excretion pattern of corticosterone metabolites collected from droppings in barnacle goslings (Branta leucopsis) raised under 24 hours of continuous natural light in the Arctic. In lower latitudes, circulating corticosterone peaks around waking and shows a nadir between midnight and 4:00, whereas the peak and nadir are time-delayed slightly when measuring corticosterone metabolites from droppings. Photoperiod, along with other environmental factors, helps to entrain an animal's endogenous rhythm to that of the natural world. North of the Arctic Circle, photoperiod may not be a reliable cue as light is continuously absent during the winter and continuously present during the summer. Here, for the first time, we used droppings to describe a 24-hour excretion pattern of corticosterone metabolites (CORTm). By applying circular statistics for dependent data, we found a diel rhythmic pattern even under continuous natural light. We discuss potential alternative 'Zeitgeber' that may function even in the polar regions, focusing on melatonin. We propose a line of research to measure melatonin non-invasively from droppings. We also provide a validation of the adopted enzyme immunoassay (EIA) that was originally developed for greylag geese.