Publication Date:
2022-05-26
Description:
Author Posting. © Company of Biologists, 2019. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 223(1), (2019): jeb.212498, doi: 10.1242/jeb.212498.
Description:
Toothed whales depend on sound for communication and foraging, making them potentially vulnerable to acoustic masking from increasing anthropogenic noise. Masking effects may be ameliorated by higher amplitudes or rates of calling, but such acoustic compensation mechanisms may incur energetic costs if sound production is expensive. The costs of whistling in bottlenose dolphins (Tursiops truncatus) have been reported to be much higher (20% of resting metabolic rate, RMR) than theoretical predictions (0.5–1% of RMR). Here, we address this dichotomy by measuring the change in the resting O2 consumption rate (V̇O2), a proxy for RMR, in three post-absorptive bottlenose dolphins during whistling and silent trials, concurrent with simultaneous measurement of acoustic output using a calibrated hydrophone array. The experimental protocol consisted of a 2-min baseline period to establish RMR, followed by a 2-min voluntary resting surface apnea, with or without whistling as cued by the trainers, and then a 5-min resting period to measure recovery costs. Daily fluctuations in V̇O2 were accounted for by subtracting the baseline RMR from the recovery costs to estimate the cost of apnea with and without whistles relative to RMR. Analysis of 52 sessions containing 1162 whistles showed that whistling did not increase metabolic cost (P〉0.1, +4.2±6.9%) as compared with control trials (−0.5±5.9%; means±s.e.m.). Thus, we reject the hypothesis that whistling is costly for bottlenose dolphins, and conclude that vocal adjustments such as the Lombard response to noise do not represent large direct energetic costs for communicating toothed whales.
Description:
M.P.B. received financial support from a Company of Biologists JEB travel fellowship JEBTF181150, and a grant from the Danish Acoustical Society. F.H.J. was supported by an AIAS-COFUND fellowship from Aarhus Institute of Advanced Studies under the FP7 program of the EU (agreement no. 609033). P.T.M. and recording equipment were funded by a large frame grant from Danish Council for Independent Research | Natural Sciences (Natur og Univers, Det Frie Forskningsråd). A.F. was supported by Fundación Oceanogràfic de la Comunitat Valenciana and Global Diving Research.
Description:
2020-12-03
Keywords:
Respiratory physiology
;
Sound production
;
Acoustic communication
;
Underwater noise
;
Vocal modifications
;
Toothed whales
Repository Name:
Woods Hole Open Access Server
Type:
Article
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