Synchronous displays are hallmarks of many animal societies, ranging from the pulsing flashes of fireflies, to military marching in humans. Such displays are known to facilitate mate attraction or ...signal relationship quality. Across many taxa, synchronous male displays appear to be driven by competition, while synchronous displays in humans are thought to be unique in that they serve a cooperative function. Indeed, it is well established that human synchrony promotes cooperative endeavours and increases success in joint action tasks. We examine another system in which synchrony is tightly linked to cooperative behaviour. Male bottlenose dolphins form long-lasting, multi-level, cooperative alliances in which they engage in coordinated efforts to coerce single oestrus females. Previous work has revealed the importance of motor synchrony in dolphin alliance behaviour. Here, we demonstrate that allied dolphins also engage in acoustic coordination whereby males will actively match the tempo and, in some cases, synchronize the production of their threat vocalization when coercing females. This finding demonstrates that male dolphins are capable of acoustic coordination in a cooperative context and, moreover, suggests that both motor and acoustic coordination are features of coalitionary behaviour that are not limited to humans.
Investigating resource partitioning among mobile marine predators such as cetaceans is challenging. Here we integrate multiple methodologies (analyses of habitat use, stable isotopes and trace ...elements) to assess ecological niche partitioning amongst two genetically divergent sympatric subpopulations (North and South) of Indo‐Pacific bottlenose dolphins (Tursiops aduncus) in Moreton Bay, Australia. Comparisons of the mean locations (latitude, longitude) and environmental variables (distance from sandbanks, distance from shore and water depth) observed at sightings of biopsy‐sampled individuals indicated that the North subpopulation occurred in the northwestern bay in significantly deeper water than the South subpopulation, which was found in southeastern nearshore waters and closer to sandbanks. Ratios of stable carbon and nitrogen isotopes in skin samples suggested that North dolphins foraged on higher trophic level prey in relatively more pelagic, offshore habitats, while South dolphins foraged on lower trophic prey in more nearshore, demersal and/or benthic habitats. Habitat partitioning was also reflected in higher blubber concentrations of most of the 13 measured trace elements, in particular lead, in the coastal South compared to the more pelagic North dolphins. These findings indicate that genetic subpopulations of bottlenose dolphins in Moreton Bay are adapted to different niches.
A bottlenose dolphin (Tursiops truncatus) housed in the Port of Nagoya Public Aquarium (PNPA) presented with symptomatic pneumonia caused by Aspergillus fumigatus. The dolphin was treated with ...micafungin. On days 2 and 11 after the first administration of micafungin, results from a physical examination and laboratory test indicated a decline of body temperature (BT) and leukopenia, with lowest BT, white blood cells (WBCs), and segmented neutrophils (SEGs) of 34.2ºC, 600 cells/μl, and 67 cells/μl, respectively. BT, WBCs, and SEGs returned to normal range after administration of granulocyte colony stimulating factor (G-CSF). To the best of our knowledge, this is the first report of micafungin-induced decline of BT and leukopenia that was successfully treated with G-CSF in a bottlenose dolphin.
Pulmonary mycosis is a fungal disease that commonly affects bottlenose dolphins (Tursiops truncatus) and is generally treated by the oral administration of azoles, such as itraconazole (ITZ) and ...voriconazole (VRZ). However, antifungal susceptibility testing of clinical isolates has not been well performed as a routine clinical examination in aquaria. In this study, we collected fungal species from the blowholes of 14 bottlenose dolphins, of which 12 were treated with ITZ or VRZ. All dolphins were housed in the Port of Nagoya Public Aquarium. The fungal species Candida albicans, C. tropicalis, C. glabrata, Aspergillus fumigatus, and A. niger were isolated. E-tests were performed to determine the minimum inhibitory concentrations (MICs) of ITZ and VRZ on these isolates. VRZ-resistant C. tropicalis (MIC: >32 μg/ml) and A. niger (MIC: >32 μg/ml) were isolated from three dolphins treated with ITZ or VRZ. Additionally, azole-resistant isolates of C. albicans and C. glabrata were collected from two dolphins that had never received azole therapy. To the best of our knowledge, our study is the first to report the isolation of VRZ-resistant C. albicans, C. tropicalis, and A. niger from the blowholes of bottlenose dolphins. Thus, antifungal susceptibility testing is a crucial strategy for selecting antifungal agents to treat respiratory fungal infections in bottlenose dolphins in aquaria.
On the captive breeding program of dolphins, it is especially important to have accurate estimation on the calving date as a part of preparation and prevention of accident during giving birth. ...Decline in body temperature is a known sign of prior to parturition therefore many facilities use this as an indicator to determine the date of calving. However, there have been a few reports that female gave birth without showing body temperature decrease. In this study, we analyzed both intermammary cleft width and body temperature changes that recorded in four cases of the birth events at our facility. The results showed that the body temperature significantly decreased one day before delivery, and the intermammary cleft width significantly increased two days before delivery. This result suggests that monitoring both intermammary cleft width and body temperature may allow earlier determination as well as accurate estimation of the date of delivery than temperature measurement alone.
Individually distinctive signature whistles are used by common bottlenose dolphins (Tursiops truncatus) during social interactions and to facilitate group cohesion. There is evidence from a few ...populations that Indian Ocean bottlenose dolphins (T. aduncus) also use signature whistles. We investigated this from a coastal resident population of T. aduncus in Mozambique. Video-audio data were collected during recreational swim-with activities over 12 years, where potential signature whistles were identified from 28 individuals. Of the 405 whistles documented, 75% were produced in SIGID bouts. Visual assessment of individual signature whistle contours demonstrated temporal stability for up to 8 years. Overall, most signature whistle types had upsweep frequency modulation and were emitted as multiloop whistles. Comparing all whistle contours to each other indicated low discrimination between individuals, with contours frequently categorised together. However, sex differences in the frequency characteristics of whistles were identified, with females whistling at lower frequencies than males. Our results indicate either a shared whistle repertoire or identity encoding with subtle contour features, requiring acute auditory perception and discrimination to decipher caller identity. More widespread geographic investigation into signature whistle use may demonstrate variation in acoustic communication systems for bottlenose dolphins, which are thus far not well understood.
Stress hormones, released into circulation as a consequence of disturbance, are classically assayed from blood samples but may also be detected in a variety of matrices. Blubber and fecal samples can ...be remotely collected from free‐ranging cetaceans without the confounding hormone elevations associated with chase, capture, and handling required to collect blood samples. The relationship between cortisol concentrations in circulation with that of blubber and feces, however, is unknown. To assess these associations, we elevated cortisol by orally administering hydrocortisone for five days in five bottlenose dolphins. Voluntary blood and fecal samples were collected daily; blubber biopsies were collected on day one, just prior to hydrocortisone administration, and days three and five of hydrocortisone administration. We evaluated subsequent changes in several circulating stress hormones as well as cortisol and glucocorticoid metabolites in blubber and feces, respectively. There was a significant association between cortisol levels in serum and in blubber (F1,12.7 = 14.3, P < 0.01, mR2 = 0.57) despite substantial variability in blubber cortisol levels. Counterintuitively, fecal cortisol metabolite levels were inversely related to serum cortisol. The relationship between serum and blubber cortisol levels suggests blubber samples from remote sampling may be useful to detect stress loads in this species.
Assisted reproduction techniques are required to maintain a genetically diverse captive population of bottlenose dolphins. These techniques include semen preservation, and liquid storage has been ...proposed as a suitable alternative to cryopreservation, but the optimum conditions, in terms of temperature, duration, and media, have yet to be fully established. The aim of this study, therefore, was to determine the optimum temperature for the liquid storage of dolphin semen during a 14-day period and the usefulness of carboxylated poly-L-lysine (CPLL) as an additive to the semen extender used for the liquid storage. The semen was collected from a mature male dolphin housed at the Kagoshima Aquarium, Japan, transferred into a Beltsville (BF5F) extender, and analyzed for motility and characteristics after five-fold dilution. The optimum temperature was determined by evaluating sperm viability after liquid storage at 4, 17, or 36 °C, and the usefulness of CPLL was evaluated at concentrations of 0%, 0.5%, 1.0%, 2.0%, and 3.0% (v/v) at the optimum temperature. Sperm stored at 4 ℃ had a greater motility maintenance compared with samples stored at 17 or 36 ℃. The most efficacious storage regimen at various time points occurred when there was addition of CPLL at 1.0% (v/v) in terms of sperm motility and other relevant determinations, with this storage approach having greater efficacy that samples stored without CPLL. The most efficacious processes for preserving bottlenose dolphin sperm functions is storage at 4 °C and with there being semen extender supplementation of 1% CPLL.
•The optimum temperature of liquid storage of bottlenose dolphin semen is 4 ℃.•The addition of carboxylated poly-L-lysine is effective in maintaining sperm motility.•Carboxylated poly-L-lysine may protect sperm cell membranes against low-temperature stress.•Improved sperm preservation techniques in bottlenose dolphins could lead to improved fertility with artificial insemination.
Evolutionary medicine expresses the present status of biomolecules affected by past evolutionary events. To clarify the whole picture of cetacean pneumonia, which is a major threat to cetaceans, ...their pulmonary immune system should be studied from the perspective of evolutionary medicine. In this in silico study, we focused on cetacean surfactant protein D (SP-D) and lipopolysaccharide-binding protein (LBP) as two representative molecules of the cetacean pulmonary immune system. Sequencing and analyzing SP-D and LBP in the bottlenose dolphin (Tursiops truncatus) lung and liver tissue collected post-mortem elucidated not only basic physicochemical properties but also their evolutionary background. This is the first study to report the sequences and expression of SP-D and LBP in the bottlenose dolphin. Besides, our findings also suggest the direction of an evolutionary arms race in the cetacean pulmonary immune system. These results have important positive implications for cetacean clinical medicine.
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•Sequence of SP-D was isolated from lung tissue in the bottlenose dolphin.•Sequence of LBP was isolated from liver tissue in the bottlenose dolphin.•Our study suggests the direction of evolutionary arms race of SP-D and LBP in the bottlenose dolphin.
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