Dynamic body acceleration as a proxy to predict the cost of locomotion in bottlenose dolphins

Abstract

Estimates of the energetic costs of locomotion (COL) at different activity levels are necessary to answer fundamental eco-physiological questions and to understand the impacts of anthropogenic disturbance to marine mammals. We combined estimates of energetic costs derived from breath-by-breath respirometry with measurements of overall dynamic body acceleration (ODBA) from biologging tags to validate ODBA as a proxy for COL in trained common bottlenose dolphins (Tursiops truncatus). We measured resting metabolic rate (RMR); mean individual RMR was 0.71-1.42 times that of a similarly sized terrestrial mammal and agreed with past measurements which used breath-by-breath and flow-through respirometry. We also measured energy expenditure during submerged swim trials, at primarily moderate exercise levels. We subtracted RMR to obtain COL, and normalized COL by body size to incorporate individual swimming efficiencies. We found both mass-specific energy expenditure and mass-specific COL were linearly related with ODBA. Measurements of activity level and cost of transport (the energy required to move a given distance) improve understanding of the costs of locomotion in marine mammals. The strength of the correlation between ODBA and COL varied among individuals, but the overall relationship can be used at a broad scale to estimate the energetic costs of disturbance, daily locomotion costs to build energy budgets, and investigate the costs of diving in free-ranging animals where bio-logging data are available. We propose that a similar approach could be applied to other cetacean species.

Surface and diving metabolic rates, and dynamic aerobic dive limits (dADL) in near‐ and off‐shore bottlenose dolphins, Tursiops spp., indicate that deep diving is energetically cheap

“…A number of estimates of FMR exist for cetaceans, but most only provide an overall cost and cannot provide estimates for specific activities (Allen, 2021;Arranz et al, 2019;Bejarano et al, 2017;Noren, 2011;Rimbach et al, 2021;Rojano-Doñate et al, 2018). Instead, researchers have established relationships between movement and energy use, which can be calibrated with dolphins in human care, and applied to movement data from wild dolphins to estimate their energetic needs (Allen et al, 2022;Fahlman et al, 2013;Williams & Noren, 2009;Williams et al, 1993Williams et al, , 2017.…”

“…A number of estimates of FMR exist for cetaceans, but most only provide an overall cost and cannot provide estimates for specific activities (Allen, 2021;Arranz et al, 2019;Bejarano et al, 2017;Noren, 2011;Rimbach et al, 2021;Rojano-Doñate et al, 2018). Instead, researchers have established relationships between movement and energy use, which can be calibrated with dolphins in human care, and applied to movement data from wild dolphins to estimate their energetic needs (Allen et al, 2022;Fahlman et al, 2013;Williams & Noren, 2009;Williams et al, 1993Williams et al, , 2017. In the current study, we used an established relationship between activity, as evaluated using ODBA, and oxygen consumption in the bottlenose dolphin (Allen et al, 2022), combined with a gas dynamic model to evaluate differences in the diving capacities and metabolic requirements of dolphins in Sarasota and Bermuda.…”

“…Instead, researchers have established relationships between movement and energy use, which can be calibrated with dolphins in human care, and applied to movement data from wild dolphins to estimate their energetic needs (Allen et al, 2022;Fahlman et al, 2013;Williams & Noren, 2009;Williams et al, 1993Williams et al, , 2017. In the current study, we used an established relationship between activity, as evaluated using ODBA, and oxygen consumption in the bottlenose dolphin (Allen et al, 2022), combined with a gas dynamic model to evaluate differences in the diving capacities and metabolic requirements of dolphins in Sarasota and Bermuda. The results demonstrate that Bermuda dolphins dive deeper and longer than the dolphins in Sarasota, and that the dADL of Bermuda dolphins is up to three times longer than that of Sarasota dolphins, mainly due to greater overall O 2 stores.…”

“…It is therefore possible that the compartment sizes, their relative metabolic rates, and the true O 2 stores are somewhere in between the nearshore ecotype (the Sarasota dolphin) and the deep diving cetaceans (Pabst et al, 2016;Velten et al, 2013). With variation in the relative muscle mass of the deep diving ecotype, it is also possible that the relationship between activity and energy cost is different compared with that developed for dolphins during shallow surface swims (Allen et al, 2022). Still, the estimated dADL of 11.1 min for deep dives was reasonably close to the estimated bADL of 9.6-10.4 min in the same dolphins (Fahlman et al, 2023), suggesting that the dynamic gas model used in the current study provides reasonable results also for deep diving dolphins.…”

“…BMR was estimated from postprandial male bottlenose dolphins that were inactive and in their thermoneutral zone (Allen et al, 2022), and ranged from 480 to 716 ml O 2 /min ( versus 634 ± 200 ml O 2 /min, respectively; Table 4) did not differ (df = 4, t = 0.12, p > .9). When analyzed together, the LMR was 8% higher at the surface: 678.…”