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Between June 1987 and March 1988, bottlenose dolphins (Tursiops truncatus Montagu 1821) along the US Atlantic coast experienced an epizootic. Monthly interquartile ranges of strandings during the epizootic were used to propose the Coastal Migratory Stock (CMS) of bottlenose dolphins (Scott et al., 1988). To date, the hypothesised CMS remains poorly understood. The goal of this study was to use a 25-year database to compare stranding patterns during the epizootic to those before (1972-1986) and after (1989-1997) the event. These comparisons reveal that monthly interquartile ranges during the epizootic are dissimilar to those before and after the event. The frequency distribution of total monthly strandings during the epizootic is also significantly different from those observed outside the event. Seasonal stranding patterns from 1989-1997 suggest more complex movements of dolphins along the US Atlantic coast than those of a single group ranging seasonally from Florida to New Jersey. In winter, for example, when the current model for the CMS predicts dolphin distributions concentrated in central Florida, the highest number of strandings occurred in North Carolina. Thus, these comparative analyses suggest that the pattern observed during the epizootic was anomalous, and not representative of stranding distributions for any other time period of the study. During the 15 years before the epizootic, and the nine years following, there was no clear picture of ‘migration’ of mortality along the coast. This study demonstrates how long-term, systematic collection of strandings data can be useful in testing hypotheses regarding the complex stock structure of coastal bottlenose dolphins. This knowledge will greatly enhance the ability to conserve and manage these animals as they recover from historic (i.e. directed takes and epizootic) and current sources of mortality.

In recent years, humpback whales (Megaptera novaeangliae) have been observed in the waters of the US mid-Atlantic states (USMA; New Jersey to North Carolina), notably in winter. The level of the mortality in this area (52 recorded deaths from 1990-2000), makes it important to understand the nature and population identity of this aggregation. Of the approximately 100 humpback whales documented in this study, photographs of 41 (live or dead) were of sufficient quality to be compared to catalogues from the Gulf of Maine (GOM, the closest feeding ground) and elsewhere in the North Atlantic. Of 22 live whales, 10 (45.5%) matched to the GOM, 5 (22.7%) to Newfoundland and 1 (4.5%) to the Gulf of St Lawrence (GSL). Of 19 dead whales, 6 (31.6%) were known GOM whales. Although the population composition of the USMA is dominated by GOM whales, lack of recent photographic effort in Newfoundland makes it likely that the observed match rates under represent the true presence of Canadian whales in the region. Length data from 48 stranded whales (18 females, 22 males and 8 of unknown sex) suggest that 39 (81.2%) were first-year animals, 7 (14.6%) were immature and 2 (4.2%) were adults. However, sighting histories of five of the dead whales indicate that some were small for their age and histories of live whales further indicate that the population contains a greater percentage of mature animals than is suggested by the stranded sample. The authors suggest that the study area primarily represents a supplemental winter feeding ground that is used by humpbacks for more than one purpose. From a management perspective, although the only successful matches of mortalities to date have been to the GOM, the observed mixing of live whales from different summer stocks might suggest that the high numbers of mortalities occurring there may not be impacting this single stock alone. Although further data are required before conclusions can be drawn, the mortality rate may be significant for the GOM population and this warrants further investigation.

In the US mid-Atlantic, multi-disciplinary studies are underway to elucidate the complex stock structure of coastal bottlenose dolphins (Tursiops truncatus), as well as the degree of overlap between coastal and offshore ecotypes. In this study we use geo-referenced data, collected during aerial surveys in 2000-2002, to describe the distribution and relative abundance of bottlenose dolphins along the US midAtlantic coast. Two aerial survey designs were used: (1) onshore/offshore surveys out to 35 n.miles during winter from Georgia to Virginia; and (2) coastal surveys throughout the year along North Carolina (NC). The winter onshore/offshore surveys demonstrated that significantly more bottlenose dolphins occur in Raleigh Bay (between Cape Hatteras and Cape Lookout, NC), than in all other regions. Additionally, in winter most bottlenose dolphins occur in the coastal waters of NC; nearly half of all sightings occurred between the shoreline and 3km from shore. The year-round, coastal surveys demonstrated that this winter distribution pattern is the result of a distinct seasonal increase in the number of dolphins within the coastal waters of NC. Circular statistical analyses demonstrated a strong influence of season on dolphin abundance. Relatively few bottlenose dolphins were observed in late spring, summer, and early autumn, with increased numbers observed during winter. In all seasons but summer, dolphin numbers were highest in Raleigh Bay. Thus, the results of both surveys indicate the importance of the habitat surrounding Cape Hatteras to bottlenose dolphins. Dolphins may preferentially use these waters in response to changes in prey distribution and/or abiotic factors such as water temperature. These results reveal an overall seasonal movement pattern along the US Atlantic coast, which appears to be correlated, at least in part, to water temperature gradients and prey availability. Although the stock identity of dolphins sighted during these aerial surveys could not be ascertained, focused photo-identification efforts, together with enhanced genetic sampling, would provide insights into the movement patterns, and, thus, stock identity, of dolphins in this region.

In this paper the occurrence, distribution and abundance of cetaceans in offshore waters of Onslow Bay, North Carolina, USA is described. Between June 2007 and June 2010 monthly aerial and shipboard line-transect surveys were conducted along ten 74km transects placed perpendicular to the shelf break. In total 42,676km of aerial trackline (218 sightings) and 5,209km of vessel trackline (100 sightings) were observed. Seven species of cetaceans were observed, but the fauna was dominated strongly by common bottlenose and Atlantic spotted dolphins. Both species were present year-round in the study area. Using photo-identification techniques, five bottlenose dolphins and one spotted dolphin were resighted during the three-year period. In general, the abundance of cetaceans in Onslow Bay was low and too few sightings were made to estimate monthly abundances for species other than bottlenose and spotted dolphins. Maximum monthly abundances of bottlenose and spotted dolphins were 4,100 (95% CI: 1,300–9,400) in May 2010 and 6,000 (95% CI: 2,500–17,400) in March 2009, respectively. Bottlenose dolphins were found throughout the study area, although they were encountered most frequently just off the shelf break. In contrast, spotted dolphins exhibited a strong preference for waters over the continental shelf and were not encountered beyond the shelf break.

Compared with terrestrial mammals, marine mammals possess increased muscle myoglobin concentrations (Mb concentration, g Mb · 100g−1 muscle), enhancing their onboard oxygen (O2) stores and their aerobic dive limit. Although myoglobin is not homogeneously distributed, cetacean muscle O2 stores have been often determined by measuring Mb concentration from a single muscle sample (longissimus dorsi) and multiplying that value by the animal’s locomotor muscle or total muscle mass. This study serves to determine the accuracy of previous cetacean muscle O2 stores calculations. For that, body muscles from three delphinid species: Delphinus delphis, Stenella coeruleoalba, and Stenella frontalis, were dissected and weighed. Mb concentration was calculated from six muscles/muscle groups (epaxial, hypaxial and rectus abdominis, mastohumeralis, sternohyoideus, and dorsal scalenus), each representative of different functional groups (locomotion powering swimming, pectoral fin movement, feeding and respiration, respectively). Results demonstrated that the Mb concentration was heterogeneously distributed, being significantly higher in locomotor muscles. Locomotor muscles were the major contributors to total muscle O2 stores (mean 92.8%) due to their high Mb concentration and large muscle masses. Compared to this method, previous studies assuming homogenous Mb concentration distribution likely underestimated total muscle O2 stores by 10% when only considering locomotor muscles and overestimated them by 13% when total muscle mass was considered.

Gut microbiomes perform crucial roles in host health and development, but few studies have explored cetacean microbiomes especially deep divers. We characterized the gut microbiomes of stranded dwarf (Kogia sima) and pygmy (K. breviceps) sperm whales to examine the effects of phylogeny and life stage on microbiome composition and diversity. 16S rRNA gene sequence analysis revealed diverse gut communities (averaging 674 OTUs) dominated by a few symbiont taxa (25 OTUs accounted for 64% of total relative abundance). Both phylogeny and life stage shaped community composition and diversity, with species-specific microbiome differences present early in life. Further analysis showed evidence of microbiome convergence with host maturity, albeit through different processes: symbiont ‘accumulation’ in K. sima and ‘winnowing’ in K. breviceps, indicating different methods of community assembly during host development. Furthermore, culture-based analyses yielded 116 pure cultures matching 25 OTUs, including one isolate positive for chitin utilization. Our findings indicate that kogiid gut microbiomes are highly diverse and species-specific, undergo significant shifts with host development, and can be cultivated on specialized media under anaerobic conditions. These results enhance our understanding of the kogiid gut microbiome and may provide useful information for symbiont assessment in host health.

Beaked whales are vulnerable to the impacts of disturbance from several sources of anthropogenic sound. Here we report the distribution and abundance of beaked whales off Cape Hatteras, North Carolina, USA, an area utilized by the U.S. Navy for training exercises, and of particular interest for seismic geophysical surveys. From May 2011 through November 2015, monthly aerial surveys were conducted at the site. Beaked whales were encountered 74 times (n= 205 individuals) during these surveys. Ziphius cavirostris, the most commonly encountered species, was observed in every month of the year. Mesoplodon spp. were encountered in ten months of the year. Photographs of adult males with erupted teeth permitted six sightings to be identified conclusively as M. europaeus; M. mirus was also photographed just outside the study area. Beaked whale surface densities stratified by depth (0.005 – 0.007/km2) were among the highest reported in the world for small ziphiids. A quantitative comparison of sightings and stranding records suggests that strandings do not accurately reflect the relative abundance of beaked whale species in this area. We conclude that Cape Hatteras, at the convergence of the Labrador Current and Gulf Stream, is a particularly important year-round habitat for several species of beaked whales. Postprint

Mesoplodont beaked whales are extreme divers, diving for over 45 mins and to depths of over 800 m. These dives are of similar depth and duration to those of the giant sperm whale (Physeter macrocephalus) whose body mass can be 50 times larger. Velten et al. (2013) provided anatomical data that demonstrated that on-board oxygen stores were sufficient to aerobically support the extreme dives of mesoplodonts if their diving metabolic rates are low. Because no physiological data yet exist, we utilized an anatomical approach-the body composition technique-to examine the relative metabolic rates of mesoplodonts. We utilized a systematic mass dissection protocol to compare the body composition of mesoplodonts with those of two short duration, shallow divers-the harbor porpoise (Phocoena phocoena) and bottlenose dolphin (Tursiops truncatus). We then investigated the body composition of two other extreme divers, the southern elephant seal (Mirounga leonina) and P. macrocephalus using data from the literature. Our results demonstrate that extreme divers invest a smaller percentage of their total body mass (TBM) in metabolically expensive brain and viscera, and a larger percent of their TBM in inexpensive integument, bone, and muscle, than do the shallow divers. Deep divers also share features of their locomotor muscle that contribute to relatively low tissue metabolic rates and high oxygen storage capacity, including large muscle fiber diameters, low mitochondrial volume densities, and high myoglobin concentrations. One feature of the locomotor muscle of mesoplodonts, though, is unique among deep divers investigated to date. Rather than having an endurance athlete's muscle fiber profile, dominated by slow oxidative fibers, mesoplodonts possess a sprinter's profile, dominated by fast glycolytic fibers. Velten et al. (2013) hypothesized that these fibers are likely inactive during routine swimming and provide a large, metabolically inexpensive oxygen store for the slow oxidative fibers to aerobically power swimming. We suggest that future anatomical analyses, coupled with performance data transduced through tagging studies, will enhance our understanding of the extreme diving capabilities of marine mammals.

Understanding toothed whale (odontocete) diving gas dynamics is important given the recent atypical mass strandings of odontocetes (particularly beaked whales) associated with mid-frequency naval sonar. Some stranded whales have exhibited gas emboli (pathologies resembling decompression sickness) in their specialized intramandibular and extramandibular fat bodies used for echolocation and hearing. These tissues have phylogenetically unique, endogenous lipid profiles with poorly understood biochemical properties. Current diving gas dynamics models assume an Ostwald nitrogen (N2) solubility of 0.07 ml N2 ml−1 oil in odontocete fats, although solubility in blubber from many odontocetes exceeds this value. The present study examined N2 solubility in the blubber and mandibular fats of seven species across five families, relating it to lipid composition. Across all species, N2 solubility increased with wax ester content and was generally higher in mandibular fats (0.083±0.002 ml N2 ml−1 oil) than in blubber (0.069±0.007 ml N2 ml−1 oil). This effect was more pronounced in mandibular fats with higher concentrations of shorter, branched fatty acids/alcohols. Mandibular fats of short-finned pilot whales, Atlantic spotted dolphins and Mesoplodon beaked whales had the highest N2 solubility values (0.097±0.005, 0.081±0.007 and 0.080±0.003 ml N2 ml−1 oil, respectively). Pilot and beaked whales may experience high N2 loads during their relatively deeper dives, although more information is needed about in vivo blood circulation to mandibular fats. Future diving models should incorporate empirically measured N2 solubility of odontocete mandibular fats to better understand N2 dynamics and potential pathologies from gas/fat embolism.

Odontocete echolocation clicks are generated by pneumatically driven phonic lips within the nasal passage, and propagated through specialized structures within the forehead. This study investigated the highly derived echolocation structures of the pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales through careful dissections (N = 18 K. breviceps, 6 K. sima) and histological examinations (N = 5 K. breviceps). This study is the first to show that the entire kogiid sound production and transmission pathway is acted upon by complex facial muscles (likely derivations of the m. maxillonasolabialis). Muscles appear capable of tensing and separating the solitary pair of phonic lips, which would control echolocation click frequencies. The phonic lips are enveloped by the “vocal cap,” a morphologically complex, connective tissue structure unique to kogiids. Extensive facial muscles appear to control the position of this structure and its spatial relationship to the phonic lips. The vocal cap's numerous air crypts suggest that it may reflect sounds. Muscles encircling the connective tissue case that surrounds the spermaceti organ may change its shape and/or internal pressure. These actions may influence the acoustic energy transmitted from the phonic lips, through this lipid body, to the melon. Facial and rostral muscles act upon the length of the melon, suggesting that the sound “beam” can be focused as it travels through the melon and into the environment. This study suggests that the kogiid echolocation system is highly tunable. Future acoustic studies are required to test these hypotheses and gain further insight into the kogiid echolocation system. Anat Rec, 298:1301–1326, 2015. © 2015 Wiley Periodicals, Inc.

Mammals host diverse bacterial and archaeal symbiont communities (i.e. microbiomes) that play important roles in digestive and immune system functioning, yet cetacean microbiomes remain largely unexplored, in part due to sample collection difficulties. Here, fecal samples from stranded pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales were used to characterize the gut microbiomes of two closely-related species with similar diets. 16S rRNA gene sequencing revealed diverse microbial communities in kogiid whales dominated by Firmicutes and Bacteroidetes. Core symbiont taxa were affiliated with phylogenetic lineages capable of fermentative metabolism and sulfate respiration, indicating potential symbiont contributions to energy acquisition during prey digestion. The diversity and phylum-level composition of kogiid microbiomes differed from those previously reported in toothed whales, which exhibited low diversity communities dominated by Proteobacteria and Actinobacteria. Community structure analyses revealed distinct gut microbiomes in K. breviceps and K. sima, driven by differential relative abundances of shared taxa, and unique microbiomes in kogiid hosts compared to other toothed and baleen whales, driven by differences in symbiont membership. These results provide insight into the diversity, composition and structure of kogiid gut microbiomes and indicate that host identity plays an important role in structuring cetacean microbiomes, even at fine-scale taxonomic levels.

Several species of odontocete cetaceans depredate bait and catch and, as a result, become hooked and entangled in pelagic longline fisheries. The present study measured how selected commercial longline hooks, including “weak hooks”, behaved within odontocete mouths. Five hooks (Mustad-16/0, Mustad-18/0, Mustad J-9/0, Korean 16, and Korean 18) were tested on three species of odontocetes known to interact with longline fisheries—short-finned pilot whales (Globicephala macrorhynchus), Risso's dolphins (Grampus griseus), and false killer whales (Pseudorca crassidens). Specimens were secured to a stanchion, hooks were placed in the mouth at multiple positions along the dorsal lip, and the force required to pull each hook free was measured. The soft tissue lips of these odontocetes were capable of resisting forces up to 250 kg before failing. The polished steel M-16, M-18, and J-9 hooks straightened at forces between 50 and 225 kg, depending on hook gauge. When straightened, these hooks exposed the sharpened barb, which sliced through the lip tissue, usually releasing the hook intact. The K-16 and K-18 hooks behaved very differently, breaking at higher forces (110–250 kg) and consistently just at the barb; usually, there was measurable soft-tissue loss and often shards of the hook were retained within those soft tissues. The different behaviours of these two hook types—the M and J type polished steel vs. the K type carbon steel—were consistent across all species tested. Mechanical tests were also conducted to determine if hooks could fracture the mandible of these same odontocetes. Only the M-18 and K-18 hooks had sufficiently large gapes to hook around the mandible, and both hook types fractured bone in short-finned pilot whales and Risso's dolphins. These results support other lines of evidence indicating that longline hooks can cause serious injury to these species, and suggest possible steps to mitigate these impacts.

Cetaceans are protected worldwide but vulnerable to incidental harm from an expanding array of human activities at sea. Managing potential hazards to these highly-mobile populations increasingly requires a detailed understanding of their seasonal distributions and habitats. Pursuant to the urgent need for this knowledge for the U.S. Atlantic and Gulf of Mexico, we integrated 23 years of aerial and shipboard cetacean surveys, linked them to environmental covariates obtained from remote sensing and ocean models, and built habitat-based density models for 26 species and 3 multi-species guilds using distance sampling methodology. In the Atlantic, for 11 well-known species, model predictions resembled seasonal movement patterns previously suggested in the literature. For these we produced monthly mean density maps. For lesser-known taxa, and in the Gulf of Mexico, where seasonal movements were less well described, we produced year-round mean density maps. The results revealed high regional differences in small delphinoid densities, confirmed the importance of the continental slope to large delphinoids and of canyons and seamounts to beaked and sperm whales, and quantified seasonal shifts in the densities of migratory baleen whales. The density maps, freely available online, are the first for these regions to be published in the peer-reviewed literature.

Marine mammal researchers and veterinarians evaluate the health of individuals and populations by using observed ranges for blood values. The goal of this study was to establish observed ranges for dependent (0-4 week) and weanling (4 week) harbor seal (Phoca vitulina) pups that were admitted for rehabilitation at the Marine Animal Lifeline in Portland, Maine from 1998-2003 and to record changes in hematologic and biochemical values as they convalesced. Blood values, measured both at admission to and release from rehabilitation, were quantitatively compared between these two groups. Of the 29 blood analytes measured in this study between dependent and weanling pups upon admission to rehabilitation, 14 were significantly different including white blood cell (WBC), red blood cell (RBC), hemoglobin (Hb), hematocrit (HCT), platelets, lymphocytes, monocytes, potassium, chloride, CO2, total bilirubin, calcium, alanine transaminase (ALT), and alkaline phosphatase. Between admission and release, 14 analytes had significantly changed for dependent pups including RBC, Hb, HCT, mean cell volume (MCV), mean corpuscular hemoglobin (MCH), platelets, lymphocytes, monocytes, potassium, blood urea nitrogen (BUN), total protein, total bilirubin, alkaline phosphatase, and ALT. Between admission and release, 10 analytes had significantly changed for weanlings including RBC, MCV, neutrophils, eosinophils, potassium, chloride, anion gap, total protein, total bilirubin, and calcium. At the time of release, six parameters were significantly different between pups admitted as dependent and those admitted as weanlings including MCV, neutrophils, eosinophils, total protein, globulin, and albumin.

SUMMARYIn Atlantic bottlenose dolphins Tursiops truncatus, both the thickness and lipid content of blubber vary across ontogeny and across individuals of differing reproductive and nutritional status. This study investigates how these changes in blubber morphology and composition influence its thermal properties. Thermal conductivity (W m–1deg.–1, where deg. is °C) and thermal insulation(m2 deg. W–1) of dolphin blubber were measured in individuals across an ontogenetic series (fetus through adult, N=36),pregnant females (N=4) and emaciated animals (N=5). These thermal properties were determined by the simultaneous use of two common experimental approaches, the heat flux disc method and the standard material method. Thickness, lipid and water content were measured for each blubber sample. Thermal conductivity and insulation varied significantly across ontogeny. Blubber from fetuses through sub-adults was less conductive(range=0.11–0.13±0.02 W m–1deg.–1) than that of adults (mean=0.18 W m–1deg.–1). The conductivity of blubber from pregnant females was similar to non-adult categories, while that of emaciated animals was significantly higher (0.24 ± 0.04 W m deg.–1) than all other categories. Blubber from sub-adults and pregnant females had the highest insulation values while fetuses and emaciated animals had the lowest. In nutritionally dependant life history categories, changes in blubber's thermal insulation were characterized by stable blubber quality (i.e. conductivity)and increased blubber quantity (i.e. thickness). In nutritionally independent animals, blubber quantity remained stable while blubber quality varied. A final, unexpected observation was that heat flux measurements at the deep blubber surface were significantly higher than that at the superficial surface, a pattern not observed in control materials. This apparent ability to absorb heat, coupled with blubber's fatty acid composition, suggest that dolphin integument may function as a phase change material.

Nine bottlenose dolphin (Tursiops truncatus) calves that stranded in Virginia in 1996 and 1997 died of severe blunt-force trauma. Injuries were concentrated on the head and chest and multiple rib fractures, lung lacerations, and soft tissue contusions were prominent. Skeletal and/or soft tissue trauma occurred bilaterally in all of the calves. One had a bite wound across the left mandible that exhibited deep punctures consistent with the tooth placement in an adult bottlenose dolphin. The lesions were not compatible with predation, boat strike, fisheries interactions, rough-surf injury, or blast injury. However, they were similar to traumatic injuries described in stranded bottlenose dolphin calves and harbor porpoises (Phocoena phocoena) in Great Britain attributed to violent dolphin interactions. The evidence suggests that violent dolphin behavior was the cause of the trauma in the nine calves reported here and that infanticide occurs in bottlenose dolphins of the western North Atlantic.

The reproductive organs of Florida manatees (Trichechus manatus latirostris) are surrounded by thermogenic locomotory muscles and insulating fat. Manatees are reported to maintain core body temperatures of 35.6°–36.4° C, temperatures known to interfere with production and maturation of viable sperm in terrestrial mammals. We describe two novel venous plexuses associated with the manatee epididymis. Each epididymis is located in a hypogastric fossa at the caudolateral extremity of the abdominal cavity. Each hypogastric fossa is lined by an inguinal venous plexus that receives cooled blood from a superficial thoracocaudal plexus. We conclude that male manatees may prevent hyperthermic insult to their reproductive tissues by feeding cooled superficial blood to venous plexuses deep within their bodies. Female manatees also possess hypogastric fossae and venous structures similar to those found in male manatees. The ovaries, uterine tubes, and distal tips of the uterine horns are located in the hypogastric fossae. We suggest that the thermovascular structures we describe also prevent hypothermic insult to female manatee reproductive tissues. The venous structures in manatees are functionally similar to structures associated with reproductive thermoregulation in cetaceans and phocid seals. Thus, these thermovascular structures appear to be convergent morphological adaptations that occur in three clades of diving mammals with independent evolutionary histories. Anat Rec 264:339–347, 2001. Published 2001 Wiley-Liss, Inc.

The similarity in swimming style and external body shape between dolphins and scombrid fishes, especially tunas, is a textbook example of evolutionary convergence. I identify additional morphological features of the musculoskeletal system shared by dolphins and tunas. Specifically, these swimmers share a pattern of force transmission through a complex, three-dimensional system of collagenous fabrics, which are stiffened by muscular hydrostatic pressure. This force transmission system increases both the displacement advantage and moment arm of contracting axial muscle. These features represent a functionally significant design for steady swimming vertebrates.

Animals can lower the metabolic cost of swimming by using appropriately tuned, elastic springs. Jet-powered invertebrates use springs that lie in functional parallel to their swimming muscles to power half the locomotor cycle. The parallel geometry constrains the spring to be non-linearly elastic; muscle power is diverted to load the spring only when swimming muscles are not capable of producing maximal hydrodynamic thrust. The springs of jellyfish and scallops are forced at or near their resonant frequency, producing large energy savings. Measuring the contribution of elastic energy storage to jet-powered locomotion has been facilitated by the relatively simple geometries of invertebrate locomotor systems. In contrast, complex musculoskeletal systems and kinematics have complicated the study of springs in swimming vertebrates. Skins, tendons and axial skeletons of some vertebrate swimmers have appropriate mechanical properties to act as springs. To date, though, there exist just a handful of studies that have investigated the mechanical behaviors of these locomotor structures in swimming vertebrates, and these data have yet to be integrated with measures of swimming power. Integrating mechanical, kinematic, hydrodynamic and metabolic data are required to understand more fully the role of elastic springs in vertebrate swimming energetics.

Most mammals possess stamina because their locomotor and respiratory (i.e. ventilatory) systems are mechanically coupled. These systems are decoupled, however, in bottlenose dolphins (Tursiops truncatus) as they swim on a breath-hold. Locomotion and ventilation appear to be coupled only during their brief surfacing event, when they respire explosively (up to 90% of total lung volume in approximately 0.3s) (Ridgway et al., 1969). The predominantly slow-twitch fiber profile of their diaphragm (Dearolf, 2003) suggests that this muscle does not likely power their rapid ventilatory event. Based upon Bramble’s (1989) biomechanical model of locomotor-respiratory coupling in galloping mammals, I hypothesized that muscles located within the cranial-cervical and lumbo-pelvic units, which act upon the thoracic unit, function to power ventilation in bottlenose dolphins. I also hypothesized that these muscles would be composed predominantly of fast-twitch fibers to facilitate the bottlenose dolphin’s rapid ventilation. The gross morphology (n=6) of cranio-cervical (sternomastoid, sternohyoid, scalenes), thoracic (intercostals), and lumbo-pelvic (rectus abdominis, abdominal obliques, hypaxialis) muscles and the fiber-type profiles (n=6) of selected muscles (sternohyoid, sternomastoid, and rectus abdominis) of bottlenose dolphins were investigated. Physical manipulations of excised thoracic units were carried out to investigate potential actions of these muscles. Results suggest that the cranio-cervical muscles act to draw the sternum and associated ribs cranio-dorsally, which flares the ribs laterally, and increases thoracic cavity volume required for inspiration. The thoracic muscles physically link the ribs to create a single functional unit; these muscles can also act to control the size of the intercostal space. The lumbo-pelvic muscles act to draw the sternum and caudal ribs caudally, which decreases the volume of the thoracic and abdominal cavities required for expiration. All muscles investigated were composed predominantly of fast-twitch fibers (range 72-88% by area) and appear histochemically poised for rapid contraction. These combined results suggest that dolphins utilize muscles, similar to those used by galloping mammals, to power their explosive ventilation. However, the mechanisms that permit dolphins to selectively couple and uncouple their locomotor and ventilatory systems, depending upon whether they are respiring at the surface or swimming on a breath-hold, remain unknown.

International audience; We present prevalence of Bartonella spp. for multiple cohorts of wild and captive cetaceans. One hundred and six cetaceans including 86 bottlenose dolphins (71 free-ranging, 14 captive in a facility with a dolphin experiencing debility of unknown origin, 1 stranded), 11 striped dolphins, 4 harbor porpoises, 3 Risso's dolphins, 1 dwarf sperm whale and 1 pygmy sperm whale (all stranded) were sampled. Whole blood ($n = 95$ live animals) and tissues ($n = 15$ freshly dead animals) were screened by PCR ($n = 106$ animals), PCR of enrichment cultures ($n = 50$ animals), and subcultures ($n = 50$ animals). Bartonella spp. were detected from 17 cetaceans, including 12 by direct extraction PCR of blood or tissues, 6 by PCR of enrichment cultures, and 4 by subculture isolation. Bartonella spp. were more commonly detected from the captive (6/14, 43%) than from free-ranging (2/71, 2.8%) bottlenose dolphins, and were commonly detected from the stranded animals (9/21, 43%; 3/11 striped dolphins, 3/4 harbor porpoises, 2/3 Risso's dolphins, 1/1 pygmy sperm whale, 0/1 dwarf sperm whale, 0/1 bottlenose dolphin). Sequencing identified a Bartonella spp. most similar to B. henselae San Antonio 2 in eight cases (4 bottlenose dolphins, 2 striped dolphins, 2 harbor porpoises), B. henselae Houston 1 in three cases (2 Risso's dolphins, 1 harbor porpoise), and untyped in six cases (4 bottlenose dolphins, 1 striped dolphin, 1 pygmy sperm whale). Although disease causation has not been established, Bartonella species were detected more commonly from cetaceans that were overtly debilitated or were cohabiting in captivity with a debilitated animal than from free-ranging animals. The detection of Bartonella spp. from cetaceans may be of pathophysiological concern.

An adult male Blainville's beaked whale (Mesoplodon densirostris) was found stranded on the Atlantic coast of the USA on 28 January 2004. Necropsy revealed a focal papilloma-like penile lesion, the cells from which revealed single 4-6 microm basophilic intranuclear inclusions. Total DNA extracted from lesion material was tested using a pan-herpes-virus PCR assay that targets the DNA polymerase gene and found to be positive. When the amplified DNA fragment was cloned, sequenced, and compared to GenBank-deposited herpesvirus DNA polymerase sequences, the detected virus was determined to be a distinct member of the Gammaherpesvirinae subfamily of herpesviruses. This new virus, tentatively named Ziphiid herpesvirus type 1, was associated with but not determined to be the cause of genital disease in the Blainville's beaked whale.

Foetal dolphins (Tursiops truncatus) are bent ventrolaterally, such that the tailflukes and lower jaw are juxtaposed. The lateral flexibility required en utero may compromise the efficiency of the dorsoventral oscillations required of the swimming neonate. The m. intertransversarius caudae dorsalis (IT) is the most laterally placed epaxial muscle. Bilateral contractions of the IT could limit lateral deformations of the flexible tailstock of the early neonate. We test the hypothesis that the IT is functioning as a postural muscle in neonates by examining its morphological, histological and biochemical properties. The neonatal IT has a relatively large cross-sectional area and bending moment, as well as a large proportion of slow-twitch fibres and elevated myoglobin concentrations. Our results demonstrate that the IT is functionally capable of performing this specific postural function in neonatal dolphins. In later life-history stages, when postural control is no longer needed, the IT serves to fine-tune the position of the tailstock during locomotion. The changing function of the adult IT is concomitant with changes in morphology and biochemistry, and most notably, with an increase in the proportion of fast-twitch fibres. We suggest that these changes reflect strong selective pressure to improve locomotor abilities by limiting lateral deformations during this critical life-history stage.

SUMMARYThe dorsal fin of the bottlenose dolphin Tursiops truncatuscontains blood vessels that function either to conserve or to dissipate body heat. Prior studies have demonstrated that heat flux, measured from a single position on the dorsal fin, decreases during body cooling and diving bradycardia and increases after exercise and at the termination of the dive response. While prior studies attributed changes in heat flux to changes in the pattern of blood flow, none directly investigated the influence of vascular structures on heat flux across the dorsal fin. In this study we examined whether heat flux is higher directly over a superficial vein,compared to a position away from a vein, and investigated the temporal relationship between heart rate, respiration and heat flux. Simultaneous records of heat flux and skin temperature at three positions on the dorsal fins of 19 wild bottlenose dolphins (with the fin in air and submerged) were collected, together with heart rate and respiration. When the fin was submerged, heat flux values were highest over superficial veins, usually at the distal tip, suggesting convective delivery of heat, via blood, to the skin's surface. Conversely, in air there was no relationship between heat flux and superficial vasculature. The mean difference in heat flux (48 W m-2) measured between the three fin positions was often equal to or greater than the heat flux that had been recorded from a single position after exercising and diving in prior studies. Tachycardia at a respiratory event was not temporally related to an increase in heat flux across the dorsal fin. This study suggests that the dorsal fin is a spatially heterogeneous thermal surface and that patterns of heat flux are strongly influenced by underlying vasculature.

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidable challenge of collecting and histologically preparing such relatively rare and large specimens. Magnetic resonance imaging offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Furthermore, internal structures can be analyzed in their precise anatomic positions, which is difficult to accomplish after the spatial distortions often accompanying histological processing. In this study, images of the brain of an adult bottlenose dolphin, Tursiops truncatus, were scanned in the coronal plane at 148 antero-posterior levels. From these scans a computer-generated three-dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three-dimensional space, was then resectioned in orthogonal planes to produce corresponding series of virtual sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of major neuroanatomical features such as the arrangement of cortical lobes and subcortical structures such as the inferior and superior colliculi, and demonstrate the utility of MRI for neuroanatomical investigations of dolphin brains.

The survival of North Atlantic right whales ( Eubalaena glacialis ) is seriously threatened by mortality caused by ships and entanglements in fishing gear. Demographic modeling indicates that the population is declining despite efforts to reduce anthropogenic mortalities, and in spite of recent increases in calving. The authors of this Policy Forum recommend immediate emergency management actions to reduce shipping and entanglement mortalities in right whales, so as to avoid a catastrophic population decline and inevitable extinction.