title: Environment and feeding change the ability of heart rate to predict metabolism in resting Steller sea lions (Eumetopias jubatus).
abstract: The ability to use heart rate (fh) to predict oxygen consumption rates ([Formula: see text]) in Steller sea lions and other pinnipeds has been investigated in fasting animals. However, it is unknown whether established fh:[Formula: see text] relationships hold under more complex physiological situations, such as when animals are feeding or digesting. We assessed whether fh could accurately predict [Formula: see text] in trained Steller sea lions while fasting and after being fed. Using linear mixed-effects models, we derived unique equations to describe the fh:[Formula: see text] relationship for fasted sea lions resting on land and in water. Feeding did not significantly change the fh:[Formula: see text] relationship on land. However, Steller sea lions in water displayed a different fh:[Formula: see text] relationship after consuming a 4-kg meal compared with the fasting condition. Incorporating comparable published fh:[Formula: see text] data from Steller sea lions showed a distinct effect of feeding after a 6-kg meal. Ultimately, our study illustrated that both feeding and physical environment are statistically relevant when deriving [Formula: see text] from telemetered fh, but that only environment affects the practical ability to predict metabolism from fh. Updating current bioenergetic models with data gathered using these predictive fh:[Formula: see text] equations will yield more accurate estimates of metabolic rates of free-ranging Steller sea lions under a variety of physiological, behavioral, and environmental states.
authors.affiliation: Marine Mammal Research Unit, Fisheries Centre, Department of Zoology, University of British Columbia, Room 247, AERL, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada. b.young@fisheries.ubc.ca
authors.forename: Beth L
authors.initials: BL
authors.lastname: Young
authors.forename: David A S
authors.initials: DA
authors.lastname: Rosen
authors.forename: Martin
authors.initials: M
authors.lastname: Haulena
authors.forename: Allyson G
authors.initials: AG
authors.lastname: Hindle
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Trites
mesh_terms: D000818:Animals; D004734:Energy Metabolism; D005215:Fasting / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D006339:Heart Rate; D016014:Linear Models; D010101:Oxygen Consumption; D046070:Sea Lions / Q000378:metabolism / Q000502:physiology*