MEPS 562:221-236 (2016)  -  DOI: https://doi.org/10.3354/meps11943

ABSTRACT: Previous research has presented contradictory evidence on the ability of overall dynamic body acceleration (ODBA) to predict mass-corrected oxygen consumption (sVO₂) in air-breathing diving vertebrates. We investigated a potential source of these discrepancies by partitioning the ODBA-sVO₂ relationship over 3 phases of the dive cycle (transiting to and from depth, bottom time, and post-dive surface interval). Trained Steller sea lions Eumetopias jubatus executed 4 types of dives to 40 m (single dives, long-duration dive bouts of 4-6 dives, short-duration dive bouts of 10 or 12 dives, and transit dives with minimal bottom duration). Partitioning single dives by dive phase showed differing patterns in the ODBA-sVO₂ relationship among dive phases, but no significant linear relationships were observed. The proportion of the dive cycle spent transiting to and from the surface was a significant predictive factor in the ODBA-sVO₂ relationship, while bottom duration or post-dive surface interval had no effect. ODBA only predicted sVO₂ for dives when the proportion of time spent transiting was small. The apparent inability of ODBA to reliably predict sVO₂ reflects differences in the inherent relationships between ODBA and sVO₂ during different phases of the dive. These results support the growing body of evidence that ODBA on its own is not a reliable field predictor of energy expenditure at the level of the single dive or dive bout in air-breathing diving vertebrates likely because ODBA (a physical measure) cannot account for physiological changes in sVO₂ that occur during the different phases of a dive cycle.

KEY WORDS: Diving behaviour · Metabolic rate · ODBA · Dive phase · Pinniped