title: Metabolic alkalosis due to feeding chicks in breeding Adélie penguins Pygoscelis adeliae under natural conditions.
abstract: Prolonged abnormal vomiting causes metabolic alkalosis. Many seabirds are known to feed their chicks by regurgitation. We hypothesized that metabolic alkalosis occurs in seabirds even under natural conditions during the breeding season. Adélie penguins Pygoscelis adeliae feed their chicks by regurgitating food for 50-60 d until the chicks fledge. In this study, the concentrations of Cl(-), HCO(3)(-), Na+, K+, pH, and PCO2 in the blood of breeding Adélie penguins were measured throughout the chick-rearing season. The pH of penguin venous blood shifted from 7.54 in the guarding period to 7.47 in the crèche period. Decreasing Cl(-) and increasing HCO(3)(-) blood concentrations in parents were associated with increasing mass of their brood in the guarding period, the early phase of the rearing season, indicating that regurgitating to feed chicks causes loss of gastric acid and results in relative metabolic alkalosis. The inverse trend was observed during the crèche period, the latter phase of the rearing season, when parents spent more time at sea and have fewer opportunities for gastric acid loss. This was assumed to be the recovery phase. These results indicate that regurgitation might cause metabolic alkalosis in breeding Adélie penguins. To our knowledge, this is the first report to indicate that seabirds exhibit metabolic alkalosis due to regurgitation to feed chicks under natural conditions.
authors.affiliation: Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, N18W9 North Ward, Sapporo 060-0818, Japan. sakamoto@vetmed.hokudai.ac.jp
authors.forename: Kentaro Q
authors.initials: KQ
authors.lastname: Sakamoto
authors.forename: Katsufumi
authors.initials: K
authors.lastname: Sato
authors.forename: Akiko
authors.initials: A
authors.lastname: Kato
authors.forename: Daisuke
authors.initials: D
authors.lastname: Fukui
authors.forename: Gen
authors.initials: G
authors.lastname: Bando
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Naito
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Habara
authors.forename: Mayumi
authors.initials: M
authors.lastname: Ishizuka
authors.forename: Shoichi
authors.initials: S
authors.lastname: Fujita
mesh_terms: D000471:Alkalosis / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001639:Bicarbonates / Q000097:blood; D005247:Feeding Behavior / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D057045:Laryngopharyngeal Reflux / Q000378:metabolism / Q000662:veterinary; D009425:Nesting Behavior / Q000502:physiology*; D011188:Potassium / Q000097:blood; D012098:Reproduction / Q000502:physiology; D012964:Sodium / Q000097:blood; D046429:Spheniscidae / Q000378:metabolism / Q000502:physiology*
chemical_list: D001639:Bicarbonates; D012964:Sodium; D011188:Potassium