Determining the energetic cost of locomotion in pilot whales and killer whales
Abstract
In addition to the effects of acoustic masking, cetaceans may perceive vessels noise and other anthropogenic sound sources as a risk and respond with avoidance behaviors or other antipredatory strategies. Avoidance behaviors can include increased levels of activity, which may impact energy budgets. Quantifying metabolic rates across a range of activity levels, from rest to intense exercise, is necessary to quantify the energetic impacts of disturbance. A number of methods to estimate the metabolic rate in marine mammals have been proposed and include breathing frequency, doubly labelled water, heart rate, and activity. Bio-logging tags have been deployed in many cetacean species, and their tri-axial accelerometers allow the calculation of movement metrics. Higher activity metric values indicate movements that require greater metabolic power. However, calibration experiments are required in order to estimate metabolic rate from activity metrics. Our first objective is to develop and test a larger pneumotachometer that is able to measure flow rates of large cetaceans. This will allow us to measure respiratory flow and exhaled O2 and CO2 which will enable us to estimate the rate of oxygen consumption (V O2) and carbon dioxide production (V CO2). Once this new flow-meter has been developed we will conduct swim trial experiments with killer whales and pilot whales at SeaWorld San Diego, in order to develop an activity-energetics proxy. We will validate the proxy by applying it to 24-hour tag deployments at SeaWorld San Diego to estimate the cost of locomotion (COL). This daily COL will be added to measured resting metabolic rate and the estimated heat increment of feeding, and this total will be compared with an independent estimatedoub of daily energy expenditure: calories ingested. After validation, the proxy can be applied to free-ranging movement tag data to look at fine to course temporal scale questions of energetic costs of locomotion.Population Consequences of Disturbance (PCoD) models are increasingly used to assess the impacts of acoustic disturbances on cetacean populations. Current bio-logging tag data and advanced analytical methods allow us to detect significant changes in activity level when animals are exposed to a source of disturbance. This study would enable future empirical parameterization of PCoD models. Researchers would be able to use existing activity data to estimate energy expenditure, thus significantly improve our understanding of the energetic costs of disturbance response. In addition, these estimates of energy expenditure are also vital to improve the estimates from gas dynamics models and would allow integration of metabolic costs to be included in future modeling efforts. In the future, when these calibrations are combined with our bottlenose dolphin data, researchers can start to explore simulated energy expenditures from tag data in species where species-specific calibrations are impossible.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- N000142012642
Entities
People
- Andrew J. Read
Organizations
- Duke University
- Office of Naval Research
- United States Navy