Figure - available from: Royal Society Open Science
This content is subject to copyright.
Predicted probabilities of detecting signals in downsampled recordings below 24 and 48 kHz. Dots and whiskers indicate the estimated marginal means for each frequency and the 95% confidence intervals, colour coded by the frequency. Estimated marginal means are back-transformed from the logit scale.
Source publication
Acoustic monitoring in cetacean studies is an effective but expensive approach. This is partly because of the high sampling rate required by acoustic devices when recording high-frequency echolocation clicks. However, the proportion of echolocation clicks recorded at different frequencies is unknown for many species, including bottlenose dolphins....
Similar publications
Introduction: The bottlenose dolphin (Tursiops truncatus) is an intermittent breather, where the breath begins with an exhalation followed by inhalation and an extended inter-breath interval ranging from 10 to 40 s. Breathing has been shown to alter both the instantaneous heart rate (if H) and stroke volume (iSV) in the bottlenose dolphin, with a t...
Human activity affects marine mammal stranding rates in two major ways; through human interaction (HI) that may lead to mortality and through search and response efforts that enable carcass detection. To better quantify the combined effects of these interacting human influences, we analyzed strandings for bottlenose dolphins (Tursiops truncatus) in...
Bottlenose dolphins (Tursiops truncatus) rely on frequency-and amplitude-modulated whistles to communicate, and noise exposure can inhibit the success of acoustic communication through masking or causing behavioral changes in the animal. At the US Navy Marine Mammal Program (MMP) in San Diego, CA, dolphins are housed in netted enclosures in the San...
The emergence of Brucella infections in marine mammals is a growing concern. The present study reports two cases of systemic Brucella pinnipedialis infection detected in bottlenose dolphins ( Tursiops truncatus ) pair stranded together in the Cantabrian coast of Spain. Both animals showed systemic lesions associated with the Brucella infection, mor...
Understanding the population health status of long-lived and slow-reproducing species is critical for their management. However, it can take decades with traditional monitoring techniques to detect population-level changes in demographic parameters. Early detection of the effects of environmental and anthropogenic stressors on vital rates would aid...
Citations
... Outside of the beam, the low-frequency components experience less attenuation and appear in the frequency spectrum 35 . Therefore, low-frequency components are expected to be predominant when free-ranging dolphin vocalizations are recorded since they are mainly off-axis of the transmitting beam 36 . In the current study, bottlenose dolphin vocalizations were recorded with no regard to specific distance or orientation from the hydrophone. ...
... In the current study, bottlenose dolphin vocalizations were recorded with no regard to specific distance or orientation from the hydrophone. Based on these considerations, it was determined that the frequency of 48 kHz could be effective for recording the entire acoustic repertoire of Tursiops truncatus, including echolocation signals, in studies analyzing the occurrence or distribution of individuals in a population or at a specific location when the presence or absence data are sufficient 36 . These observations indicate that the present database recorded at 192 kHz could be suitable for the majority of dolphin vocalization analyses. ...
Globally, interactions between fishing activities and dolphins are cause for concern due to their negative effects on both mammals and fishermen. The recording of acoustic emissions could aid in detecting the presence of dolphins in close proximity to fishing gear, elucidating their behavior, and guiding potential management measures designed to limit this harmful phenomenon. This data descriptor presents a dataset of acoustic recordings (WAV files) collected during interactions between common bottlenose dolphins (Tursiops truncatus) and fishing activities in the Adriatic Sea. This dataset is distinguished by the high complexity of its repertoire, which includes various different typologies of dolphin emission. Specifically, a group of free-ranging dolphins was found to emit frequency-modulated whistles, echolocation clicks, and burst pulse signals, including feeding buzzes. An analysis of signal quality based on the signal-to-noise ratio was conducted to validate the dataset. The signal digital files and corresponding features make this dataset suitable for studying dolphin behavior in order to gain a deeper understanding of their communication and interaction with fishing gear (trawl).
... Outside the beam, the low-frequency components suffer less attenuation and appear in the frequency spectrum [35]. Thus, low-frequency components are expected to be predominant when free-ranging dolphin vocalizations are recorded since they are mainly off-axis of the transmitting beam [36]. It is worth recalling that the CoPiDi hydrophone was developed with just the main aim of measuring free-ranging dolphin vocalizations. ...
... It is worth recalling that the CoPiDi hydrophone was developed with just the main aim of measuring free-ranging dolphin vocalizations. Moreover, based on the abovementioned analyses, a study by Romeu et al. showed that a sampling frequency of 48 kHz (and thus recorded bandwidth = 24 kHz) may be effective for recording the entire acoustic repertoire of Turpsiops truncatus when employed in studies analyzing and quantifying the presence/absence of the single animal or a population of cetaceans in a specific location [36]. For all the situations described above, the proposed hydrophone appears to be a suitable tool for recording dolphin's vocalization, especially considering its low cost. ...
Passive acoustics are widely used to monitor the presence of dolphins in the marine environment. This study aims to introduce a low-cost and homemade approach for assembling a complete underwater microphone (i.e., the hydrophone), employing cheap and easy to obtain components. The hydrophone was assembled with two piezo disks connected in a balanced configuration and encased in a plastic container filled with plastic foam. The hydrophone’s performance was validated by direct comparison with the commercially available AS-1 hydrophone (Aquarian Hydrophones, Anacortes, U.S.) on different underwater acoustic signals: artificial acoustic signals (ramp and multitone signals) and various dolphin vocalizations (whistle, echolocation clicks, and burst pulse signals). The sensitivity of the device’s performance to changes in the emission source position was also tested. The results of the validation procedure on both artificial signals and real dolphin vocalizations showed that the significant cost savings associated with cheap technology had a minimal effect on the recording device’s performance within the frequency range of 0–35 kHz. At this stage of experimentation, the global cost of the hydrophone could be estimated at a few euros, making it extremely price competitive when compared to more expensive commercially available models. In the future, this effective and low-cost technology would allow for continuous monitoring of the presence of free-ranging dolphins, significantly lowering the total cost of autonomous monitoring systems. This would permit broadening the monitored areas and creating a network of recorders, thus improving the acquisition of data.
