Meeting Abstract
As a shallow diving marine mammal with a low energy herbivorous diet, West Indian manatees (Trichechus manatus) have developed adaptations to maximize energy efficiency. In addition to a low resting metabolic rate (RMR), our current research suggests that West Indian manatees have adapted their diving physiology to minimize oxygen debt during a dive. These adaptations, however, might not be optimized for the behavioral changes resulting from boat traffic, such as an increase in respiration variability. Despite a calculated aerobic dive limit greater than 18 minutes and a maximum observed dive duration of 24 minutes, the average dive duration for most behaviors is less than 3 minutes. To determine the energetic consequences of extended dives, we used flow-through respirometry to measure the energetic cost of stationary dives in 2 adult manatees at Mote Marine Laboratory & Aquarium (Sarasota, FL). For dives within preferred dive durations (< 3 min) the average recovery MR was 0.99 ml O2·kg-1·min-1, 11% lower than the average resting MR (1.11 ml O2·kg-1·min-1), indicating no incurred oxygen debt. For longer dive durations (4-8 min), the animals began to incur an oxygen debt, exhibiting an average recovery MR of 1.76 ml O2·kg-1·min-1 (59% higher than RMR) for a dive MR of 0.64 ml O2·kg-1·min-1. This suggests a dive physiology optimized for short duration dives and has implications for how these animals respond to anthropogenic disturbances in the wild.
