[MARMAM] New Publication: Raise your pitch! Changes in the acoustic emissions of resident bottlenose dolphins in the proximity of vessels

Filipa Alexandra Veiga Sobreira FSobreira at ispa.pt
Sun Jan 28 12:11:49 PST 2024

Dear MARMAM Colleagues,

On behalf of my co-authors, I am delighted to announce the publication of our recent paper:

Sobreira, F. V., Luís, A. R., Alves, I. S., Couchinho, M. N., & dos Santos, M. E. (2023). Raise your pitch! Changes in the acoustic emissions of resident bottlenose dolphins in the proximity of vessels. Marine Mammal Science, 1–11.

Maritime traffic is a major contributor of anthropogenic disturbance for cetaceans, especially for coastal populations, such as that of resident common bottlenose dolphins (Tursiops truncatus) in the Sado estuary (Portugal). Animals have been found to adjust their vocal behavior by changing vocal rates, or call frequency and/or duration, to overcome masking effects of underwater noise. To evaluate the potential impacts of boat traffic on the acoustic behavior of these dolphins, emission rates and acoustic characteristics of whistles and burst-pulsed signals were analyzed with and without boats operating nearby. In this study, no significant differences were found for emission rates of each type of vocal element in the presence of vessels. However, significant differences were found in acoustic parameters, namely changes in frequency and duration, for whistles and for pulsed sounds (creaks, grunts, squeaks, and gulps). These changes, such as a shift in vocal frequencies and production of shorter signals, may represent behavioral strategies to compensate for the noisy environment. Although resident bottlenose dolphins in the Sado region seem to have developed some tolerance to vessel noise, continuous noise exposure and noise-induced frequency shifts in vocal outputs could have indirect fitness costs for this population.

Best regards,
Filipa V. Sobreira

MSc in Marine Biology
fsobreira at ispa.pt
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