CONICET | Buscador de Institutos y Recursos Humanos

We measured the metabolic rate of nineteen wild and three captive, trained Southern sea lions (Otaria flavescens, Shaw 1800) during three behavioral states: resting in air (V . O2 rest air), resting in water (V . O2 rest water) and submerged swimming (V . O2 subswim) using open flow respirometry. We then used these values to estimate total cost of transport (COT) and cost per stroke (CPS) during submerged swimming. Wild animals were placed in a metabolic chamber, and captive animals were trained to breathe under a plexiglass dome mounted at the end of a pool. General linear modeling was used to determine whether the incidence of each type of response variable (V . O2, CPS, COT, swim speed and stroke rate) could be associated with several explanatory variables (sex, age, animal identity, behavioral state, swimming distance and body mass). The overall mean V . O2 rest air was 6.8 ± 1.1 ml O2 min-1 kg-1 (n= 20 animals; 7 subadult males, 10 sub-adults females, 3 adults females), which was 2.1 times greater than the predicted basal metabolic rate (BMR) for terrestrial mammals of similar size, and neither body mass nor sex had a significant influence. The mean V . O2 rest air when only adults were considered (6.3 ± 0.3 ml O2 min-1 kg-1; n= 3 females) was similar to the overall value. The mean ¬ V . O2 rest water (9.0 ± 0.8 ml O2 min-1 kg-1) and the mean V . O2 subswim (21.2 ± 7.4 ml O2 min-1 kg-1) estimated from repeated measurements in two adult females were 2.9 and 6.8 times greater than the predicted BMR, respectively. Both ¬ V . O2 rest water and V . O2 subswim were significantly greater (1.4 and 3.4 times respectively) than the mean V . O2 rest air estimated in this study, when only adults were compared. The mean COT was 0.14 ± 0.1 ml O2 kg-1 m-1 (2.6 ± 1.0 J kg-1 m-1), and the mean CPS was 0.38 ± 0.3 ml O2-1 kg-1 stroke-1; none of these values were significantly different among animals.

enviar mensaje