CIE Spotlight: Transiting to depth disrupts overall dynamic body acceleration and oxygen consumption rate in freely diving Steller sea lions

John A.

Authors: Beth L. Volpov, Elizabeth T. Goundie, David A.S. Rosen, Andrew W. Trites, John P. Y. Arnould

SourceMarine Ecology Progress Series, 562:221-236, December 29 2016

Brief summary of the paper: Previous research has presented contradictory evidence on the ability of overall dynamic body acceleration (ODBA) to predict mass-corrected oxygen consumption (sV ̇ O2) in air- breathing diving vertebrates.

We investigated a potential source of these discrepancies by partitioning the ODBA−sV ̇ O2 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−sV ̇O2 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−sV ̇ O2 relationship, while bottom duration or post-dive surface interval had no effect. ODBA only predicted sV ̇ O2 for dives when the proportion of time spent transiting was small. The apparent inability of ODBA to reliably predict sV ̇ O2 reflects differences in the inherent relationships between ODBA and sV ̇ O2 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 sV ̇ O2 that occur during the different phases of a dive cycle.