Activity and diving metabolism correlate in Steller sea lion Eumetopias jubatus

Abstract

Three Steller sea lions Eumetopias jubatus were trained to participate in free-swimming, open-ocean experiments designed to determine if activity can be used to estimate the energetic cost of finding prey at depth. Sea lions were trained to dive to fixed depths of 10 to 50 m, and to re-surface inside a floating dome to measure energy expenditure via gas exchange. A 3-axis accelerometer was attached to the sea lions during foraging. Acceleration data were used to determine the overall dynamic body acceleration (ODBA), a proxy for activity. Results showed that ODBA correlated well with the diving metabolic rate (dive + surface interval) and that the variability in the relationship (r 2 = 0.47, linear regression including Sea lion as a random factor) was similar to that reported for other studies that used heart rate to estimate metabolic rate for sea lions swimming underwater in a 2 m deep water channel. A multivariate analysis suggested that both ODBA and dive duration were important for predicting diving metabolic cost, but ODBA alone predicted foraging cost to within 7% between animals. Consequently, collecting 3-dimensional acceleration data is a simple technique to estimate field metabolic rate of wild Steller sea lions and other diving mammals and birds.

Assessing the Validity of the Accelerometry Technique for Estimating the Energy Expenditure of Diving Double-Crested CormorantsPhalacrocorax auritus

“…A recent study of Steller sea lions Eumetopias jubatus reported a significant relationship between and ODBA at the tem-VO 2 c poral scale assessed in our study (Fahlman et al 2008b). However, reanalysis of figure 2 in Fahlman et al (2008b) returns a coefficient of determination (r 2 ) value of 0.14; in contrast, during terrestrial locomotion, variation in ODBA typically accounts for more than 80% of the variation in (e.g., Halseẏ VO 2 et al 2009c).…”

“…However, reanalysis of figure 2 in Fahlman et al (2008b) returns a coefficient of determination (r 2 ) value of 0.14; in contrast, during terrestrial locomotion, variation in ODBA typically accounts for more than 80% of the variation in (e.g., Halseẏ VO 2 et al 2009c). A second significant regression presented in Fahlman et al (2008b) includes the same data plus data for nondiving rest periods at the surface. In this case, the strength of the relationship is reported and is slightly greater, having a correlation coefficient (r) of 0.47.…”

Construction of energy landscapes can clarify the movement and distribution of foraging animals

“…Extensive recent work has shown a linear relationship between ODBA and metabolic rate in all species examined to date, which includes fish [25], amphibia [26], mammals and birds [27][28][29][30][31][32], and this has been explicitly defined in cormorants for resting, diving and walking by Gomez Laich et al [33] as…”

Convergent evolution in locomotory patterns of flying and swimming animals

“…3). Assuming an underlying linear relationship of ODBA and oxygen consumption 19,20,22 , the elephant seal saved between 13% and 35.6% of activityrelated metabo lism by utilizing intermittent locomotion at depth greater than ~15 m compared with continuous locomotion at shallower depths (Fig. 3).…”

“…3; y = 0.94x + 0.33; r 2 = 0.36; F 1,76 = 42.43, P < 0.0001). Detailed analysis of locomotory effort through the activity metric overall dynamic body acceleration (ODBA) 19,20 , which integrates estimated metabolic effort for movement over limbstroke frequency and amplitude 21 , revealed this elephant seal utilized a smaller range of locomotory power output in 'undulating locomotion' (1st and 3rd quartile of measured ODBA: 0.12 g and 0.14 g, respectively) compared with continuous locomotion (1st and 3rd quartile of measured ODBA: 0.09 g and 0.15 g, respectively). A direct comparison of undulating flight and continuous locomotion at corresponding velocities revealed that the elephant seal engaged in less locomotory power output (as ascertained by ODBA) while swimming intermittently (Fig.…”