Cetaceans rely heavily on sound, as the marine environment is particularly well-suited for this communication type. Costs associated with sound production has been studied for several species of Avians and Amphibians but has only been sparsely studied in marine mammals. Previous estimates of sound production costs for bottlenose dolphins (Tursiops truncatus) are seemingly very high, which, if true is of concern as this can represent a significant energy investment, and one that is expected to increase as animals adjust their vocal behavior by calling more loudly or shifting their calling frequency in response to background noise (The Lombard Response). However, these previous studies have experimental concerns due to a lack of a proper control period and the use of a large dome-respirometer, leading to uncertainties regarding the accuracies of metabolic rate estimation, both concerns which I seek to alleviate.
In my master’s project, I aim to investigate if sound production is energetically expensive for dolphins. In collaboration with Oceanografic in Valencia, I will be conducting the study on captive bottlenose dolphins during the fall in 2018. Metabolic rate will be estimated using respirometry with the resident Dr. Andreas Fahlman’s pneumotachometer which offers more accuracy compared to a dome-respirometer due to the smaller volume, for silent and vocalizing periods, and the energetic contents of whistles will be estimated from source level captured with a hydrophone at a known distance. From these, the energetic costs of sound production as well as the sound production efficiency can be estimated and compared to that of other species.