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Background and Aim: Cetaceans and sirenians are endangered marine mammals that are threatened by stranding and mortality. In Thailand’s Andaman Sea, limited data exist on the causes and patterns of these events. This retrospective study investigated the characterization and underlying causes of cetacean and sirenian mortality events in the Andaman Sea from 2018 to 2023 using information from the Department of Marine and Coastal Resources, Thailand. Materials and Methods: Data on 363 stranded marine mammals, including both live and dead strandings, species types, carcass condition, and necropsy findings and diagnoses, were gathered and analyzed to classify and determine the main factors contributing to mortality, encompassing both direct human-related and non-direct human-related causes. Results: From 2018 to 2023, 231 cetaceans and 132 sirenians were documented, representing six families and 19 species. Of these animals, 18.18% (66/363) were stranded alive and 81.81% (297/363) were found dead. The most common species were dugong (Dugong dugon) and Indo-Pacific humpback dolphin (Sousa chinensis). Detailed postmortem analyses of 107 specimens showed that 17.76% (19/107) of deaths were anthropogenic, affecting 8 sirenians and 11 cetaceans. The majority of deaths were non-anthropogenic, involving 34 sirenians and 54 cetaceans. In addition, 223 stranded animals could not be fully assessed due to carcass condition. Conclusion: A high cetacean and sirenian mortality rate in the Andaman Sea can be attributed to non-anthropogenic factors. The dugong and Indo-Pacific humpback dolphin were the most frequently encountered species. This report enhances our understanding of marine mammal mortality in Thailand and underscores the need for improved health management and diagnostic responses.

Understanding reproductive output and success is integral to the conservation and management of threatened species and populations. Little is known about the reproductive parameters of Australian humpback dolphins (Sousa sahulensis), a species subject to cumulative pressures from anthropogenic threats due to their coastal distribution and strong site fidelity. This study assesses several reproductive parameters, including crude birth, recruitment, fecundity, and calf survival rates, in addition to interbirth intervals of Australian humpback dolphins inhabiting the near‐urban embayment of Moreton Bay, Queensland. Between 2014 and 2020, 106 adult females were photographically identified during 222 boat surveys. Of these, 75.5% (n = 80) were observed with calves. Birth seasonality was apparent and coincided with austral autumn and winter months. Interbirth intervals ranged between 1 and >6 years, with an average of 3.1 (SD = 1.1) years if offspring survived. Findings indicate declining fecundity rates (p <.05, M = 0.12, SD = 0.02), relatively low recruitment rates (M = 0.04, SD = 0.01) and calf survival rates to 1 year of age (M = 0.63, SD = 0.15). This study provides a useful baseline that can inform viability assessments and conservation measures, for both this population and others throughout the species range. [ABSTRACT FROM AUTHOR]

The transboundary area of the Strait of Gibraltar is home to seven protected cetacean species that are threatened by high intensity of maritime traffic. More comprehensive knowledge of cetaceans and maritime traffic is required, together with analyses of legislations, strategies and policies.This study quantitatively investigates cetacean distribution and maritime traffic intensity and, for the species of community interest bottlenose dolphin, habitat suitability. Results are qualitatively discussed considering the overlap of cetacean hot spots with different maritime activities and the consistency of spatial conservation management measures in force.The Fixed Line Transect Mediterranean Monitoring Network protocols were followed for 59 visual surveys using ferries as observation platforms for monitoring cetaceans and maritime traffic. Surveys were carried out along the transects between Algeciras and Ceuta and between Algeciras and Tanger‐Med, in 2018 and 2019. 264 cetacean sightings, including seven different species and four near‐miss collision events (involving pilot, sperm and fin whales), were reported.Monitoring cetaceans from ferries in the Strait provided insights into cetacean distribution and maritime traffic, enabling the identification of cetacean hot spots, suitable habitats and maritime traffic high‐risk zones.A transboundary management effort is required, together with an adaptive approach for protecting highly mobile species such as cetaceans. Proposals include a long‐term cetacean monitoring program carried out by dedicated observers on board ferries as a cost‐effective methodology and mandatory training for crew members, to increase cetacean knowledge and reduce collision risk.The designation of an international temporal or, in some zones, permanent speed reduction area (i.e., Cetacean Critical Navigation Zone, with a maximum speed of 13 knots) and of a micro‐sanctuary with a seasonal no‐take zone in the Bay between Algeciras and Gibraltar, together with international surveillance, are recommended measures for the enhancement of conservation efforts in the Strait. [ABSTRACT FROM AUTHOR]

Analyses of the spatial and temporal patterns of 26 years of stranding events (1995–2011 and 2012–2021, n = 568) in Indonesia were conducted to improve the country’s stranding response. The Emerging Hot Spot Analysis was used to obtain the spatial and temporal hotspot patterns. A total of 92.4% events were single stranding, while the remaining were of mass stranding events. More stranding events were recorded between 2012 and 2021 in more dispersed locations compared to the previous period. Within the constraints of our sampling limitations, East Kalimantan and Bali were single stranding hotspots and consecutive hotspots. East Java and Sabu-Raijua in East Nusa Tenggara were mass stranding hotspots. Temporally, Raja Ampat (West Papua) experienced a significant increase in case numbers. The presence of active NGOs, individuals or government agencies in some locations might have inflated the numbers of reported cases compared to areas with less active institutions and/or individuals. However, our results still give a good understanding of the progression of Indonesia’s stranding responses and good guidance of resource allocation for the stranding network. Several locations in Indonesia that need more efforts (e.g., more training workshops on rescue and necropsies) have been identified in this paper. Suggestions to improve data collection (including georeferencing tips) have also been included.

Virtually all land mammals and birds have two sleep states: slow-wave sleep (SWS) and rapid eye movement (REM) sleep [1, 2]. After deprivation of REM sleep by repeated awakenings, mammals increase REM sleep time [3], supporting the idea that REM sleep is homeostatically regulated. Some evidence suggests that periods of REM sleep deprivation for a week or more cause physiological dysfunction and eventual death [4, 5]. However, separating the effects of REM sleep loss from the stress of repeated awakening is difficult [2, 6]. The northern fur seal (Callorhinus ursinus) is a semiaquatic mammal [7]. It can sleep on land and in seawater. The fur seal is unique in showing both the bilateral SWS seen in most mammals and the asymmetric sleep previously reported in cetaceans [8]. Here we show that when the fur seal stays in seawater, where it spends most of its life [7], it goes without or greatly reduces REM sleep for days or weeks. After this nearly complete elimination of REM, it displays minimal or no REM rebound upon returning to baseline conditions. Our data are consistent with the hypothesis that REM sleep may serve to reverse the reduced brain temperature and metabolism effects of bilateral nonREM sleep, a state that is greatly reduced when the fur seal is in the seawater, rather than REM sleep being directly homeostatically regulated. This can explain the absence of REM sleep in the dolphin and other cetaceans and its increasing proportion as the end of the sleep period approaches in humans and other mammals.

Analyses of the spatial and temporal patterns of 26 years of stranding events (1995–2011 and 2012–2021, n = 568) in Indonesia were conducted to improve the country's stranding response. The Emerging Hot Spot Analysis was used to obtain the spatial and temporal hotspot patterns. A total of 92.4% events were single stranding, while the remaining were of mass stranding events. More stranding events were recorded between 2012 and 2021 in more dispersed locations compared to the previous period. Within the constraints of our sampling limitations, East Kalimantan and Bali were single stranding hotspots and consecutive hotspots. East Java and Sabu-Raijua in East Nusa Tenggara were mass stranding hotspots. Temporally, Raja Ampat (West Papua) experienced a significant increase in case numbers. The presence of active NGOs, individuals or government agencies in some locations might have inflated the numbers of reported cases compared to areas with less active institutions and/or individuals. However, our results still give a good understanding of the progression of Indonesia's stranding responses and good guidance of resource allocation for the stranding network. Several locations in Indonesia that need more efforts (e.g., more training workshops on rescue and necropsies) have been identified in this paper. Suggestions to improve data collection (including georeferencing tips) have also been included. [ABSTRACT FROM AUTHOR]

The vast majority of bacterial diversity lies within phylum-level lineages called "candidate phyla," which lack isolated representatives and are poorly understood. These bacteria are surprisingly abundant in the oral cavity of marine mammals. We employed a genome-resolved metagenomic approach to recover and characterize genomes and functional potential from microbes in the oral gingival sulcus of two bottlenose dolphins (Tursiops truncatus). We detected organisms from 24 known bacterial phyla and one archaeal phylum. We also recovered genomes from two deep-branching, previously uncharacterized phylum-level lineages (here named "Candidatus Delphibacteria" and "Candidatus Fertabacteria"). The Delphibacteria lineage is found in both managed and wild dolphins; its metabolic profile suggests a capacity for denitrification and a possible role in dolphin health. We uncovered a rich diversity of predicted Cas9 proteins, including the two longest predicted Cas9 proteins to date. Notably, we identified the first type II CRISPR-Cas systems encoded by members of the Candidate Phyla Radiation. Using their spacer sequences, we subsequently identified and assembled a complete Saccharibacteria phage genome. These findings underscore the immense microbial diversity and functional potential that await discovery in previously unexplored environments.

The survival rates for the exposed classes for age HT ht and year HT ht were then: HT ht and 1 HT ht for females and males, respectively. [Extracted from the article]

A recent assessment of spatial conservation priorities in mega-diverse Papua New Guinea noted a lack of marine data. We surveyed cetaceans in inshore and pelagic waters along the south coast of New Britain island. The total number of cetaceans encountered was 397, attributed to at least 6 species, with spinner dolphins and pantropical spotted dolphins both the most frequently sighted and abundant species. Although diversity and abundance were lower than expected, we hope that by contributing to a national cetacean sightings database this survey will support a growing understanding of marine mammal diversity and distribution within the region. Marine spatial planning in Papua New Guinea is impeded by a lack of data on the abundance and distribution of high biodiversity values. We surveyed cetaceans in inshore and pelagic waters along the south coast of New Britain in March 2020. We document our sightings of six species, and highlight emerging resources for contributing observations to a growing data repository. Photograph by Lisle Gwynn. [ABSTRACT FROM AUTHOR]

Dolphin behavior and cognition have been studied in both the laboratory and the wild. Laboratory studies provide high levels of control over experimental variables and the opportunity to investigate the cognitive mechanisms of behavior. However, laboratory studies are typically limited to a few subjects. Field studies have the benefit of examining behavior and social interactions among large numbers of individuals. They can reveal how cognitive abilities are expressed naturally, and can provide external validity for observations in the laboratory. However, there is typically less controlover experimental variables in field studies than in the laboratory. Thus, a synergistic relationship has emerged between laboratory and field studies of dolphin behavior and cognition with each contributing information and ideas to the other that can lead to new questions and insights. This relationship is demonstrated using four issues: a) the types of percepts and mental representations dolphins can form through echolocation; b) the complexity of relationships that dolphins can understand; c) the dolphin's competency in symbolic referential communication; and d) the dolphin's ability to manage joint attention through pointing and gazing.

Dolphin behavior has been observed in both captive and wild settings for years. Comparisons of captive and wild aquatic mammals have proven difficult because of limitations placed on observers in both arenas; still research conducted in each setting provides details often unavailable from the other environment. For example, internal body states (e.g., hormone levels) that might effect the expression of certain behaviors cannot readily be measured from wild dolphins; however, they can be routinely documented during husbandry behaviors. Conversely, detailed documentation of dolphin travel patterns is more readily available from long-term studies of wild dolphins; and while travel patterns are not applicable for study from captive individuals, observation of movement patterns within a pool can be examined to provide insight into an individual’s behavior or inter-individual interactions. Long-term observations from three captive and three wild dolphins study populations are presented comparatively to illustrate how work on groups in each setting can complement one another. Additionally, data from a survey of trainers (50 surveys distributed with 17 completed surveys received) suggests that dolphin trainers interpreted several behaviors in ways that were consistent with observations of wild dolphins. For example, tail slapping was reported mainly as irritation(45.5%) or frustration (22.7%), but was also suggested to occur in play (31.8%). Pectoral fin rubs were used in appeasement (15.4%), comfort (7.7%), and affection (26.9%) more so than in sexual(7.7%) contexts or not at all (7.7%). Jaw claps, hitting, biting, chasing and ramming were observed in aggressive contexts in both captivity and the wild. More significantly, there were no consistent differences between wild and captive dolphins reported by surveyed trainers. The author’s ongoing research program merges advantages from both environments to facilitate a more thorough understanding of dolphin communication and society.

The study of individual differences in animals and humans has flourished in recent years. This work has revealed personality traits in a wide range of species, including dolphins. However, there are few systematic studies of dolphin personality despite many reasons to assume that personality plays an important role in dolphin behavior. Dolphins live in complex societies and demonstrate a broad and diverse behavioral repertoire, which allows for the possibility of consistent individual differences. In this paper, we discuss the available evidence for individual differences and personality in dolphins from a variety of behavioral contexts from both captive and wild populations, as well as the significance of such differences for theories of dolphin behavior, dolphin welfare, and conservation.

The present study examined the ability of dolphins to follow the gestural signs presented by humantrainers in various attentional states in order to understand the social cognition of dolphins. Thehuman trainers enacted the gestural signs by orienting their bodies and heads in different directions.If the dolphins were attending to the attentional state of the human trainers, their performances wouldbe affected by the orientation of the head only. Results showed, however, that the dolphins’ behaviorswere controlled by the orientation of the trainers’ bodies rather than that of their heads. Twoadditional tests further supported the minimal impact of head orientation on responses to humangestural signs. The present results might be influenced by the current experimental setting, thus weneed further efforts to accumulate empirical evidence on social cognition in dolphins.

Many people agree that dolphins are sentient beings, but few would claim to know what being a dolphin is like. From a psychological perspective, a dolphin’s experiences are a function of its mental capacities, especially those processes that relate to memories, percepts, thoughts, and emotions. This paper reviews what is currently known about dolphins’ cognitive abilities, focusing on how they perceive and remember events. Experiments with captive dolphins show that they can flexibly access memories of past events and construct sophisticated representations of the world and themselves.How dolphins act and what they remember about their actions impacts what they perceive, which in turn guides their thoughts and decisions. Many of the actions and events that shape a dolphin’s experience are internally generated and monitored. Knowing how dolphins perceive temporal patterns, objects, emotions, actions, agents, scenes, messages, and motivations can help clarify what dolphins’ thoughts, memories, and experiences are like. Only by giving dolphins a way to show what they know, or can learn, can we hope to understand what goes on inside their heads.

Many non-human species imitate the behavior of others, and dolphins seem particularly adept at this form of observational learning. Evidence for observational learning in wild dolphins is rare, given the difficulty of observing individual wild animals in sufficient detail to eliminate other possible explanations of purported imitation. Consequently, much of the evidence supporting observational learning in dolphins has involved animals in captive settings. This research suggests that dolphins have an affinity for mimicry, and that they are more successful at observational learning if they choose to imitate another rather than being asked to do so. These results, combined with those obtained from wild dolphins, suggest that imitation may play important roles in the ontogeny of a variety of behaviors, including those involved in communication, foraging, and parenting.

This study investigated the ability of a bottlenose dolphin to adapt a previously learned "do-as-I-do"procedure to copy behaviors of another dolphin while blindfolded (i.e., wearing eyecups). In Experiment 1, the dolphin was able to copy both vocal and motor behaviors, whether blindfolded or sighted. Hydrophone recordings showed that he echolocated during many of the motor behaviors while blindfolded. In Experiment 2, blindfolded human trainers were able to identify the same model behaviors on the basis of their characteristic sounds. While it thus remains unclear whether the dolphin recognized the motor behaviors via echolocation or via their characteristic sounds, this is the first demonstration of such flexibility in using a new perceptual route to motor imitation in a nonhuman animal.

To date in Sri Lankan waters, there has been limited research on Killer Whales. These animals have been recorded almost all around the island, except in the northernmost waters and in Palk Bay. The highest observed concentrations are from the northeastern, south/southwestern and northwestern coastal waters of Sri Lanka. These have come from both opportunistic observations and dedicated scientific surveys. Seasonal trends in sightings in some locations suggest fairly consistent occupancy. Transient Killer Whales have been documented attacking/killing Sperm Whales from many geographic locations around the world. To date, there is only one published account of Killer Whales feeding in Sri Lankan waters. Our paper presents, for the first time, field observations of Killer Whales preying upon superpods of Sperm Whales in the waters off the Kalpitiya Peninsula (eastern half of the Gulf of Mannar), northwestern Sri Lanka. The incidents took place on two separate occasions during the months of March and April, 2017. [ABSTRACT FROM AUTHOR]

Bottlenose dolphins make many different sounds that have been recorded and described by researchers for over 60 years. This species, Tursiops truncatus, is arguably the most studied marine mammal. They have the ability to hear and produce sounds over a range of at least 150 kilohertz (kHz). Although the human hearing is limited in bandwidth to less than 20 kHz, dolphin sounds have historically been described as humans perceive them (e.g. whistles, squeals, buzzes, barks, quacks, pops, etc.). Often the same names have been used for different sounds and different names have been used for sounds that are apparently the same. In this review, we try and summarize the dolphin sound literature and provide standardized spectrograms where possible. Our goal is to provide a foundation for future research to build upon by providing a tool for identifying whether a sound has been described before. Novel sound types can then be recognized. Also, we encourage future studies that show when dolphins perceive two sound types as different. Detailed reports linking sound and behaviour are also essential. Only then can we have a complete idea of the dolphin repertoire and begin to understand how they use sound for communication. [ABSTRACT FROM AUTHOR]

The monitoring of herpesvirus infection provides useful information when assessing marine mammals’ health. This paper shows the prevalence of herpesvirus infection (80.85%) in 47 cetaceans stranded on the coast of the Valencian Community, Spain. Of the 966 tissues evaluated, 121 tested positive when employing nested-PCR (12.53%). The largest proportion of herpesvirus-positive tissue samples was in the reproductive system, nervous system, and tegument. Herpesvirus was more prevalent in females, juveniles, and calves. More than half the DNA PCR positive tissues contained herpesvirus RNA, indicating the presence of actively replicating virus. This RNA was most frequently found in neonates. Fourteen unique sequences were identified. Most amplified sequences belonged to the Gammaherpesvirinae subfamily, but a greater variation was found in Alphaherpesvirinae sequences. This is the first report of systematic herpesvirus DNA and RNA determination in free-ranging cetaceans. Nine (19.14%) were infected with cetacean morbillivirus and all of them (100%) were coinfected with herpesvirus. Lesions similar to those caused by herpesvirus in other species were observed, mainly in the skin, upper digestive tract, genitalia, and central nervous system. Other lesions were also attributable to concomitant etiologies or were nonspecific. It is necessary to investigate the possible role of herpesvirus infection in those cases.

Unmanned aerial systems (UASs) are powerful tools for research and monitoring of wildlife. However, the effects of these systems on most marine mammals are largely unknown, preventing the establishment of guidelines that will minimize animal disturbance. In this study, we evaluated the behavioral responses of coastal bottlenose dolphins (Tursiops truncatus) and Antillean manatees (Trichechus manatus manatus) to small multi-rotor UAS flight. From 2015 to 2017, we piloted 211 flights using DJI quadcopters (Phantom II Vision +, 3 Professional and 4) to approach and follow animals over shallow-water habitats in Belize. The quadcopters were equipped with high-resolution cameras to observe dolphins during 138 of these flights, and manatees during 73 flights. Aerial video observations of animal behavior were coded and paired with flight data to determine whether animal activity and/or the UAS's flight patterns caused behavioral changes in exposed animals. Dolphins responded to UAS flight at altitudes of 11–30 m and responded primarily when they were alone or in small groups. Single dolphins and one pair responded to the UAS by orienting upward and turning toward the aircraft to observe it, before quickly returning to their pre-response activity. A higher number of manatees responded to the UAS, exhibiting strong disturbance in response to the aircraft from 6 to 104 m. Manatees changed their behavior by fleeing the area and sometimes this elicited the same response in nearby animals. If pursued post-response, manatees repeatedly responded to overhead flight by evading the aircraft's path. These findings suggest that the invasiveness of UAS varies across individuals, species, and taxa. We conclude that careful exploratory research is needed to determine the impact of multi-rotor UAS flight on diverse species, and to develop best practices aimed at reducing the disturbance to wildlife that may result from their use.

The use of aquatic mammals as bait to enhance the harvest of fisheries species has garnered little attention by the scientific and conservation communities, often receiving only brief mention in reports focused on the human consumption or bycatch of aquatic mammals. A number of studies, however, highlight the negative impact of this practice on affected mammal populations. A systematic review of relevant literature published since 1970 yields new insight into the scope of the issue. Findings indicate that the practice of using aquatic mammals for bait has been and continues to be geographically widespread, has affected at least 42 species, and often involves deliberate killing for the express purpose of securing bait. The nature of the fisheries involved is diverse, encompassing a wide range of target species and gear types; however, shark fisheries that employ longlines appear to be the most widely engaged in using aquatic mammals as bait. This practice appears to be most common in Latin America and Asia. It is evident, based on our review, that there is little information on the impact of the direct take on most targeted mammal populations, commonly small cetaceans, and increased monitoring efforts are needed in many locales. In most instances, the ecology and population dynamics of the targeted fishery species is poorly understood and in some cases the species is classified as threatened, suggesting a fishery sustainability issue that cannot be fully addressed with a substitute for the aquatic mammal bait. It is essential that natural resource managers implement mitigation approaches that consider the socio-economic, cultural, political, and ecological circumstances leading to the use of aquatic mammal bait in each fishery.

A bipolar, single-lead electrocardiogram (ECG) device is capable of recording ECGs with an integrated smartphone application. To determine the utility of this device, phone-based ECGs (pECG) were compared with standard six-lead ECGs (sECG) in four female Atlantic bottlenose dolphins (Tursiops truncatus) at the National Aquarium. Study animals were trained to haul out onto a dry deck in ventral recumbency and allow simultaneous 30-sec ECG acquisition using the two devices. The pECG device was held against the thoracic wall caudal to the left axilla. The sECGs were recorded in the frontal plane. Instantaneous heart rates were obtained from identical QRS complexes on both ECGs. Three boarded cardiologists independently evaluated the rhythm and the polarity of the QRS depolarization for each recording and the results were compared. The mean heart rate was 80 beats/min (range 62–92 beats/min) and 80 beats/min (range 60–92 beats/min) for the pECG and sECGs, respectively. All four dolphins displayed sinus respiratory arrhythmia, and one animal had occasional atrial premature contractions. Rhythm diagnosis and QRS polarity were identical for the pECG and sECG. Dolphin vocalizations created artifacts on the pECG that were not present on the sECG, so pECGs had to be acquired without vocalization. The pECG appears to be an accurate and useful method to monitor the heart rate in Atlantic bottlenose dolphins. This system is inexpensive and portable, making it valuable for health examinations, transport monitoring, and stranding responses. [ABSTRACT FROM AUTHOR]

Systemic steroid hormone measurements are often used in the assessment of reproductive, developmental, and stress physiology in vertebrates. In protected wildlife, such as the common bottlenose dolphin ( Tursiops truncatus ), these measures can provide critical information about health and fitness to aid in effective conservation and management. Circulating steroid hormone concentrations are typically measured by immunoassays, which have imperfect specificity and are limited to the measurement of a single hormone per assay. Here we demonstrate that reverse phase solid phase extraction (SPE) coupled to liquid chromatography tandem mass spectrometry (LC–MS/MS) allows for the simultaneous, precise (<15% relative standard deviation), and accurate (between 70% and 120% recovery of spiked quantities) measurement of at least seven steroid hormones in dolphin plasma. These seven steroid hormones include three hormones that have been measured previously in bottlenose dolphin blood (progesterone, testosterone, and cortisol) and three hormones which have never been quantified in dolphin blood (17-hydroxyprogesterone, androstenedione, cortisone, and corticosterone). While 17β-estradiol was not detected endogenously, we were able to accurately and precisely measure spiked quantities estradiol. Measures from plasma were more precise (i.e., lower RSD) than serum, and thus we recommend plasma as the preferred matrix for this analytical method. In order to facilitate comparison of current and future plasma-based studies to previous serum-based studies, we characterized the relationships between hormone measurements in matched plasma and serum, and found that measurements across matrices are significantly and positively correlated. Lastly, to demonstrate potential applications of this method, we examined how steroid hormone profiles vary by pregnancy, sexual maturity, and stress status – pregnancy was associated with elevated progesterone, adult males had higher testosterone, and capture stress was associated with elevated corticosteroids. Overall, we conclude that this method will enable investigators to more thoroughly and efficiently evaluate steroid hormone homeostasis in bottlenose dolphins compared to immunoassay methods. These methods can potentially be applied to the assessment of sexual maturity/seasonality, pregnancy status, and stress in free-ranging bottlenose dolphins as well as those maintained under human care, and potentially other marine mammals. [ABSTRACT FROM AUTHOR]

The study of marine soundscapes is a growing field of research. Recording hardware is becoming more accessible; there are a number of off-the-shelf autonomous recorders that can be deployed for months at a time; software analysis tools exist as shareware; raw or preprocessed recordings are freely and publicly available. However, what is missing are catalogues of commonly recorded sounds. Sounds related to geophysical events (e.g. earthquakes) and weather (e.g. wind and precipitation), to human activities (e.g. ships) and to marine animals (e.g. crustaceans, fish and marine mammals) commonly occur. Marine mammals are distributed throughout Australia's oceans and significantly contribute to the underwater soundscape. However, due to a lack of concurrent visual and passive acoustic observations, it is often not known which species produces which sounds. To aid in the analysis of Australian and Antarctic marine soundscape recordings, a literature review of the sounds made by marine mammals was undertaken. Frequency, duration and source level measurements are summarised and tabulated. In addition to the literature review, new marine mammal data are presented and include recordings from Australia of Omura's whales ( Balaenoptera omurai), dwarf sperm whales ( Kogia sima), common dolphins ( Delphinus delphis), short-finned pilot whales ( Globicephala macrorhynchus), long-finned pilot whales ( G. melas), Fraser's dolphins ( Lagenodelphis hosei), false killer whales ( Pseudorca crassidens), striped dolphins ( Stenella coeruleoalba) and spinner dolphins ( S. longirostris), as well as the whistles and burst-pulse sounds of Australian pygmy killer whales ( Feresa attenuata). To date, this is the most comprehensive acoustic summary for marine mammal species in Australian waters. [ABSTRACT FROM AUTHOR]

Parainfluenza virus (PIV) is a leading cause of respiratory infections in humans. A novel virus closely related to human and bovine parainfluenza viruses types 3 (HPIV-3 and BPIV-3), named Tursiops truncatus parainfluenza virus type 1 (TtPIV-1), was isolated from a dolphin with respiratory disease. We developed a dolphin-specific ELISA to measure acute- and convalescent-phase PIV antibodies in dolphins during 1999–2006 with hemograms similar to that of the positive control. PIV seroconversion occurred concurrently with an abnormal hemogram in 22 animals, of which 7 (31.8%) had respiratory signs. Seroprevalence surveys were conducted on 114 healthy bottlenose dolphins in Florida and California. When the most conservative interpretation of positive was used, 11.4% of healthy dolphins were antibody positive, 29.8% were negative, and 58.8% were inconclusive. PIV appears to be a common marine mammal virus that may be of human health interest because of the similarity of TtPIV-1 to BPIV-3 and HPIV-3.

A 1.5-year-old male, 100 kg, Atlantic bottlenose dolphin, Tursiops truncatus, was evaluated for chronic ulcerative stomatitis of unknown etiology and 1-year duration. Multiple ulcerative lesions were seen on the gingiva and hard palate. Antibiotics and anti-fungal agents had been administered, which had failed to resolve the lesions. From the initial history and traditional Chinese veterinary medicine (TCVM) examination, a diagnosis of Excess Stomach Heat/Fire and Blood Heat was made. The dolphin was treated with the Chinese Herbal medicine, Blood Heat Formula, a proprietary blend of Yu Jin (Curcuma), Dan Shen (Salvia), Chi Shao (Paeonia), Sheng Di Huang (Rehmannia), Huang Bai (Phellodendron), Di Fu Zi (Kochia), Xuan Shen (Scrophularia), Mai Men Dong (Ophiopogon) and Mu Dan Pi (Moutan). The herbal powder (4 g) was placed in fish and fed to the dolphin twice daily for 6 months. No adverse side effects were seen. Four months after initiation of treatment, the lesions had decreased 95% and they had resolved by 9 months. A recurrence of smaller lesions was seen 4 months after discontinuing the herbal medicine. The dolphin was again treated for 6 months with Blood Heat Formula and the lesions improved, but a few did not completely resolve. Stomach Yin Deficiency was then suspected. Qing Wei San was administered for 6 months and all lesions resolved except a small resolving lesion on the mandible. This case is an example of the TCVM examination, pattern identification and use of Chinese herbal medicine to manage a chronic debilitating problem in dolphins. [ABSTRACT FROM AUTHOR]

A hallmark of the dive response, bradycardia, promotes the conservation of onboard oxygen stores and enables marine mammals to submerge for prolonged periods. A paradox exists when marine mammals are foraging underwater because activity should promote an elevation in heart rate (fH) to support increased metabolic demands. To assess the effect of the interaction between the diving response and underwater activity on fH, we integrated interbeat fH with behavioral observations of adult bottlenose dolphins diving and swimming along the coast of the Bahamas. As expected for the dive response, fH while resting during submergence (40±6 beats min-1) was significantly lower than fH while resting at the water surface (105±8 beats min-1). The maximum recorded fH (fH,max) was 128±7beatsmin-1, and occurred during post-dive surface intervals. During submergence, the level of bradycardia was modified by activity. Behaviors such as simple head bobbing at depth increased fa by 40% from submerged resting levels. Higher heart rates were observed for horizontal swimming at depth. Indeed, the dolphins operated at 37-58% of their fH,max while active at depth and approached 57--79% of their fH,max during anticipatory tachycardia as the animals glided to the surface. fH was significantly correlated with stroke frequency (range=0-2.5 strokes s-1 r=0.88, N=25 dives) and calculated swim speed (range=0-5.4ms-1, r=0.88, N= 25 dives). We find that rather than a static reflex, the dive response is modulated by behavior and exercise in a predictable manner. [ABSTRACT FROM AUTHOR]

Steno bredanensis (Cuvier in Lesson, 1828) is a small odontocete commonly called the rough-toothed dolphin. A slender, gray dolphin with a slightly darker cape, this species is most easily distinguished from other small delphinids by a gradually sloping forehead and a long rostrum. It is the only species in the genus Steno. Despite reports of sightings or stranded specimens from all tropical and subtropical oceans, the species is thought to typically occur in low abundance. The conservation status of S. bredanensis is poorly known. [ABSTRACT FROM AUTHOR]

Blubber is a critical component of thermoregulation for marine mammals, particularly for cetaceans. However, the cost of overcoming blubber's buoyant force during descent could constrain blubber deposition. One- to 12-year-old healthy, free-ranging common bottlenose dolphins (Tursiops truncatus) were studied in Sarasota Bay, Florida, during summer (mean water temperature: 29.7°C ± 0.1 SE) and winter (mean water temperature: 19.2 ± 0.4°C) to examine ontogenetic and seasonal trends in morphology and blubber deposition. Surface-area-to-volume ratio decreased significantly with age. During summer, yearlings had significantly thicker blubber than 2- to 12-year-old animals but this difference diminished by winter because blubber deposition in response to the colder water temperature was smaller in yearlings (2-mm increase) compared to 2- to 12-year-old animals (3- to 6-mm increase). During summer, buoyancy was highest in yearlings (6.24 N ± 0.41 SE), compared to a buoyant force of -0.98 ± 0.90 N (neutrally buoyant) for 12-year-old animals. Conversely, all dolphins converged upon a similar buoyant force (8.01 ± 0.56 N) in winter. The elevated buoyancy of yearlings in summer presumably limits seasonal blubber adjustments, because all yearlings (regardless of season) converged upon a similar calculated mass-specific cost of descent that was greater than all other age classes. Balancing energetic demands of thermoregulation and locomotion may limit the flexibility of yearlings to adjust blubber deposition in response to fluctuating water temperatures. [ABSTRACT FROM AUTHOR]

Understanding the effects of natural environmental variation on biodiversity can help predict response to future anthropogenic change. Here we analyse a large, long-term data set of sightings of deep-water cetaceans from the Atlantic, Pacific and Indian Oceans. Seasonal and geographic changes in the diversity of these genera are well predicted by a convex function of sea-surface temperature peaking at c. 21 °C. Thus, diversity is highest at intermediate latitudes – an emerging general pattern for the pelagic ocean. When applied to a range of Intergovernmental Panel on Climate Change global change scenarios, the predicted response is a decline of cetacean diversity across the tropics and increases at higher latitudes. This suggests that deep-water oceanic communities that dominate > 60% of the planet’s surface may reorganize in response to ocean warming, with low-latitude losses of diversity and resilience. [ABSTRACT FROM AUTHOR]

The aerobic dive limit (ADL) and the hypothesis that most dives are aerobic in nature have become fundamental to the understanding of diving physiology and to the interpretation of diving behavior and foraging ecology of marine mammals and seabirds. An ADL, the dive duration associated with the onset of post-dive blood lactate accumulation, has only been documented with blood lactate analyses in five species. Applications to other species have involved behavioral estimates or use of an oxygen store / metabolic rate formula. Both approaches have limitations, but have proved useful to the evaluation of the dive behavior and ecology of many species. Unlabelled Image • Aerobic dive limit (ADL): dive duration associated with the onset of post-dive blood lactate accumulation • ADL concept: most dives of marine mammals and seabirds are aerobic • ADL only determined with blood lactate measurements in five species • Physiological basis of the ADL: muscle O 2 depletion and subsequent glycolysis • Estimation of ADL in other species → widespread application to interpretation of dive behavior and ecology • Behavioral estimation of the ADL: dive duration distribution and dive duration-surface interval criteria • Mathematical estimation of ADL: O 2 stores / diving metabolic rate [ABSTRACT FROM AUTHOR]

Perfluoroalkyl substances (PFASs) are a class of organohalogenated compounds of environmental concern due to similar characteristics as the well-studied legacy persistent organic pollutants (POPs) that typically show environmental persistence, biomagnification and toxicity. Nevertheless, PFAS are still poorly regulated internationally and in many aspects poorly understood. Here, we studied liver and muscle concentrations in five cetacean species stranded at the southeastern coast of Spain during 2009–2018. Twelve of the fifteen targeted compounds were detected in >50% of the liver samples. Hepatic concentrations were significantly higher than those in muscle reflecting the particular toxicokinetics of these compounds. Bottlenose dolphins Tursiops truncatus showed the highest hepatic ΣPFAS (n = 5; 796.8 ± 709.0 ng g−1 ww) concentrations, followed by striped dolphin Stenella coeruleoalba (n = 29; 259.5 ± 136.2 ng g−1 ww), sperm whale Physeter macrocephalus (n = 1; 252.8 ng g−1 ww), short-beaked common dolphin Delphinus delphis (n = 2; 240.3 ± 218.6 ng g−1 ww) and Risso's dolphin Grampus griseus (n = 1; 78.7 ng g−1 ww). These interspecies differences could be partially explained by habitat preferences, although they could generally not be related to trophic position or food chain proxied by stable N (δ15N) and C (δ13C) isotope values, respectively. PFAS profiles in all species showed a similar pattern of concentration prevalence in the order PFOS>PFOSA>PFNA≈PFFUnA>PFDA. The higher number of samples available for striped dolphin allowed for evaluating their PFAS burden and profile in relation to the stranding year, stable isotope values, and biological variables including sex and length. However, we could only find links between δ15N and PFAS burdens in muscle tissue, and between stranding year and PFAS profile composition. Despite reductions in the manufacturing industry, these compounds still appear in high concentrations compared to more than two decades ago in the Mediterranean Sea and PFOS remains the dominating compound. Image 1 • PFASs was measured in five endemic Mediterranean cetacean' species. • PFAS burdens are higher than those reported two decades ago. • PFOS and PFOSA are the dominant PFAS components of profiles. • Concentrations were higher in the coastal bottlenose dolphin. • Trophic position explains PFAS muscle burdens of striped dolphin. Main findings: First study conducted in more than two decades of PFAS in stranded western Mediterranean. Despite its phase-out in the EU some of the PFAS burdens found can be considered high. [ABSTRACT FROM AUTHOR]