Dolphin-Watching Boats Affect Whistle Frequency Modulation in Bottlenose Dolphins

Bottlenose dolphins’ whistles are key in social communication, conveying information about conspecifics and the environment. Therefore, their study can help to infer habitat use and identify areas of concern due to human activities. Here we studied the whistles of bottlenose dolphins (Tursiops truncatus) in two sites of the archipelago of Bocas del Toro, Panama, that contrast in boat traffic. Almirante Bay is a site dominated by taxi-boats and Dolphin Bay is a major location for boat-based dolphin watching. Recordings were made using bottom-mounted hydrophones and from the research boat using an over-the-side hydrophone and a broadband recording system. A total recording effort time of 1,726 h was analyzed. Our results show significant differences in boat detection between sites, and a higher number of whistles detected per minute in the site with tour-boat traffic. Furthermore, whistle modulation accounted for most of the differences between sites, boat presence, and whistle types. Dolphin whistle modulation is thought to be a potential indicator of emotional states including danger, alertness, and stress. In this study, dolphin signature whistle modulation increased significantly with boat presence in both sites but changes in modulation were greater in Dolphin Bay where tour-boats directly and sometimes aggressively interact with the animals. These results support a potential association between whistle modulation and stress (or alertness). These findings indicate that if tour-boat captains behave more like taxi-boat captains by e.g., reducing the distance of approach and contact time during dolphin interactions, dolphin communication, and emotional state would be less disrupted. These measures are implemented in the national guidelines for whale-watching and are known to tour-boat operators. The key to protecting these dolphins is in finding ways to effectively enforce these operator guidelines.

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Spectrum Analysis Signature Whistle of Bottlenose Dolphins (Tursiops aduncus) at Captive, Indonesia with Yule-Walker AR and Welch Power Spectral Density Method

Journal of Marine Science Research & Development ◽

10.4172/2155-9910.1000195 ◽

2016 ◽

Vol 6 (3) ◽

Author(s):

Muhammad Zainuddin Lubis ◽

Pratiwi Dwi Wulandari

Keyword(s):

Spectral Density ◽

Power Spectral Density ◽

Spectrum Analysis ◽

Bottlenose Dolphins ◽

Tursiops Aduncus ◽

Density Method ◽

Power Spectral ◽

Signature Whistle ◽

Spectral Density Method

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Distance does matter: close approaches by boats impede feeding and resting behaviour of Indo-Pacific bottlenose dolphins

Wildlife Research ◽

10.1071/wr11048 ◽

2011 ◽

Vol 38 (6) ◽

pp. 455 ◽

Cited By ~ 11

Author(s):

Andre Steckenreuter ◽

Robert Harcourt ◽

Luciana Möller

Keyword(s):

Bottlenose Dolphins ◽

Tourism Industry ◽

Empirical Measures ◽

Resting Behaviour ◽

South Wales ◽

Animal Populations ◽

Conflicting Objectives ◽

Dolphin Population ◽

Direction Of Movement ◽

Dolphin Watching

Context Potential impacts of human disturbance on animal populations can be measured as behavioural responses and may affect the survival and fecundity of animals. In areas where human–wildlife interactions occur, conservation management needs to be in place to secure both a viable tourism industry and the sustainability of the targeted species. Aims We sought to evaluate whether different approach distances by boat have effects on the behaviour and group cohesion of dolphins that are targeted by Australia’s largest dolphin-watching industry. Methods The effects of different approach distances of boats on the behavioural states of dolphins, group dispersal and direction of movement were investigated in this area by controlled boat experiments conducted between August 2008 and December 2009. Key results Results showed that there was significantly less feeding when boats approached dolphin groups to a distance of 50 m than when they did to a distance of 150 m, or with controlled approaches. Resting was also observed significantly less when boats approached to a distance of 50 m than when they approached to a distance of 150 m. The dispersal of dolphin groups was significantly tighter (less dispersed) when boats approached to 50 m than that with 150-m-distance or controlled approaches. Furthermore, the dolphins’ direction of movement was less neutral when the experimental boat approaches were carried out at a distance of 50 m than when they were carried out at a distance of 150 m, or with controlled approaches. Similar results were also obtained for dolphin groups including calves. Conclusions On the basis of the results from this study, we recommend that the existing New South Wales regulations, which stipulate that dolphin-watching boats keep a distance of 50 m to groups with adults only and 150 m to groups with calves, are maintained within the Port Stephens–Great Lakes Marine Park (PSGLMP). Implications Management plans whose stated goals include both sustainability of a dolphin-watching industry and longer-term viability of a dolphin population may reconcile conflicting objectives and improve their decision making by using these empirical measures rather than best guesses.

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A Genetics-Based Method for Analysing and Synthesizing Animal Vocal Communication and its Application to Bottlenose Dolphins' Signature Whistle Analysis and Generation

Acta Acustica united with Acustica ◽

10.3813/aaa.919205 ◽

2018 ◽

Vol 104 (4) ◽

pp. 657-667

Author(s):

Krzysztof W. Zuber ◽

Krzysztof J. Opieliński

Keyword(s):

Vocal Communication ◽

Bottlenose Dolphins ◽

Signature Whistle

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Tandem Pore Domain Potassium Channels

The Oxford Handbook of Neuronal Ion Channels ◽

10.1093/oxfordhb/9780190669164.013.4 ◽

2019 ◽

Author(s):

Douglas A. Bayliss

Keyword(s):

Single Channel ◽

Resting Membrane Potential ◽

K2p Channel ◽

Physiological Processes ◽

System A ◽

Wide Range ◽

K2p Channels ◽

To Come ◽

A Site ◽

Pore Domain

The KCNK gene family encodes two-pore-domain potassium (K2P) channels, which generate the background (“leak”) K+ currents that establish a negative resting membrane potential in cells of the nervous system. A pseudotetrameric K+-selective pore is formed by pairing channel subunits, each with two pore-domains, in homo- or heterodimeric conformations. Unique features apparent from high-resolution K2P channel structures include a domain-swapped extracellular cap domain, a lateral hydrophobic-lined fenestration connecting the lipid bilayer to the channel vestibule, and an antiparallel proximal C-terminal region that links the paired subunits and provides a site for polymodal channel modulation. Individual channels transition between open and closed states, with the channel gate located at the selectivity filter. In general, K2P channels display relatively modest voltage- and time-dependent gating, together with distinct single-channel rectification properties, that conspire to yield characteristic weakly rectifying macroscopic currents over a broad range of membrane potentials (i.e., background K+ currents). Of particular note, K2P channel activity can be regulated by a wide range of physicochemical factors, neuromodulators, and clinically useful drugs; a distinct repertoire of activators and inhibitors for different K2P channel subtypes endows each with unique modulatory potential. Thus, by mediating background currents and serving as targets for multiple modulators, K2P channels are able to dynamically regulate key determinants of cell-intrinsic electroresponsive properties. The roles of specific K2P channels in various physiological processes and pathological conditions are now beginning to come into focus, and this may portend utility for these channels as potential therapeutic targets.

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