Search

Histopathological and immunohistochemical methods were used to diagnose round cell tumors in 2 subantarctic fur seals Arctocephalus tropicalis with marked anemia. Although wild-born, both individuals were placed under human care while juveniles in a Brazilian aquarium. Both pinnipeds were PCR tested for herpesvirus, and 1 was infected with otariid gammaherpesvirus 5 (OtHV-5), previously described in a subantarctic fur seal stranded in Brazil. Although some gammaherpesviruses can cause sarcomas and other neoplasms, it was not possible to definitively associate OtHV-5 with the neoplasm. To our knowledge, these are the first neoplasm records in subantarctic fur seals.

Secondarily aquatic tetrapods have many unique morphologic adaptations for life underwater compared with their terrestrial counterparts. A key innovation during the land‐to‐water transition was feeding. Pinnipeds, a clade of air‐breathing marine carnivorans that include seals, sea lions, and walruses, have evolved multiple strategies for aquatic feeding (e.g., biting, suction feeding). Numerous studies have examined the pinniped skull and dental specializations for underwater feeding. However, data on the pinniped craniofacial musculoskeletal system and its role in aquatic feeding are rare. Therefore, the objectives of this study were to conduct a comparative analysis of pinniped craniofacial musculature and examine the function of the craniofacial musculature in facilitating different aquatic feeding strategies. We performed anatomic dissections of 35 specimens across six pinniped species. We describe 32 pinniped craniofacial muscles—including facial expression, mastication, tongue, hyoid, and soft palate muscles. Pinnipeds broadly conform to mammalian patterns of craniofacial muscle morphology. Pinnipeds also exhibit unique musculoskeletal morphologies—in muscle position, attachments, and size—that likely represent adaptations for different aquatic feeding strategies. Suction feeding specialists (bearded and northern elephant seals) have a significantly larger masseter than biters. Further, northern elephant seals have large and unique tongue and hyoid muscle morphologies compared with other pinniped species. These morphologic changes likely help generate and withstand suction pressures necessary for drawing water and prey into the mouth. In contrast, biting taxa (California sea lions, harbor, ringed, and Weddell seals) do not exhibit consistent craniofacial musculoskeletal adaptations that differentiate them from suction feeders. Generally, we discover that all pinnipeds have well‐developed and robust craniofacial musculature. Pinniped head musculature plays an important role in facilitating different aquatic feeding strategies. Together with behavioral and kinematic studies, our data suggest that pinnipeds’ robust facial morphology allows animals to switch feeding strategies depending on the environmental context—a critical skill in a heterogeneous and rapidly changing underwater habitat., Pinnipeds (seals, sea lions, and walruses) have strong, powerful craniofacial muscles that reflect their aquatic habitat and underwater feeding strategies. Their well‐developed facial expression, mastication, tongue, and hyoid muscles allow pinnipeds to successfully capture prey in dynamic marine ecosystems across the globe.

Pinnipeds have evolved enlarged ocular bulbs to catch fish in the dark. However, their large protruding eyes are easily damaged, which increases the risk of blindness and death in these animals. In captivity, ophthalmic disorders, manifested as keratitis and cataracts, are common among pinnipeds. In this study, we investigated symptoms of ophthalmic disorders in pinniped species using a questionnaire distributed to 32 zoos and aquariums throughout Japan. We conducted this study in cooperation with the Japanese Association of Zoos and Aquariums. The survey included 295 pinnipeds from four otariid species, five phocid species, and one odobenid species. Of these, 43.1% of the pinnipeds had diseases affecting the lens, cornea, and/or other eye parts. Age was positively associated with lens disorders in California sea lions, South American sea lions, and spotted seals. Conflicts and public appearances were also associated with corneal and/or lens disorders in California sea lions. Treatments were evaluated as effective for corneal disorders and conjunctivitis. The results of this study indicate that ophthalmic disorders in pinnipeds are related to the conditions of their captive environment. Aquariums and zoos should be encouraged to share information regarding optimal maintenance practices to improve the living conditions of pinnipeds.

Regulations designed to mitigate the effects of man-made sounds on marine mammal hearing specify maximum daily sound exposure levels. The limits are lower for impulsive than non-impulsive sounds. The regulations do not indicate how to quantify impulsiveness; instead sounds are grouped by properties at the source. To address this gap, three metrics of impulsiveness (kurtosis, crest factor, and the Harris impulse factor) were compared using values from random noise and real-world ocean sounds. Kurtosis is recommended for quantifying impulsiveness. Kurtosis greater than 40 indicates a sound is fully impulsive. Only sounds above the effective quiet threshold (EQT) are considered intense enough to accumulate over time and cause hearing injury. A functional definition for EQT is proposed: the auditory frequency-weighted sound pressure level (SPL) that could accumulate to cause temporary threshold shift from non-impulsive sound as described in Southall, Finneran, Reichmuth, Nachtigall, Ketten, Bowles, Ellison, Nowacek, and Tyack [(2019). Aquat. Mamm. 45, 125-232]. It is known that impulsive sounds change to non-impulsive as these sounds propagate. This paper shows that this is not relevant for assessing hearing injury because sounds retain impulsive character when SPLs are above EQT. Sounds from vessels are normally considered non-impulsive; however, 66% of vessels analyzed were impulsive when weighted for very-high frequency mammal hearing.

Hypotension is a common adverse effect of general anesthesia that has historically been difficult to measure in pinniped species due to technical challenges. A retrospective case review found seven pinniped cases that demonstrated anesthesia-associated hypotension diagnosed by direct blood pressure measurements during general anesthesia at The Marine Mammal Center (Sausalito, CA) between 2017 and 2019. Cases included five California sea lions (CSL: Zalophus californianus), one Hawaiian monk seal (HMS: Neomonachus schauinslandi), and one northern elephant seal (NES: Mirounga angustirostris). Patients were induced using injectable opioids, benzodiazepines, and anesthetics including propofol and alfaxalone. Excluding the HMS, all patients required supplemental isoflurane with a mask to achieve an anesthetic plane allowing for intubation. Each patient was maintained with inhalant isoflurane in oxygen for the duration of the anesthetic event. Each patient was concurrently administered continuous IV fluids and four patients received fluid boluses prior to administration of ephedrine. All hypotensive anesthetized patients were treated with IV ephedrine (0.05–0.2 mg/kg). The average initial systolic (SAP) and mean (MAP) arterial blood pressures for the CSL prior to ephedrine administration were 71 ± 14 mmHg and 48 ± 12 mmHg respectively. The average SAP and MAP for the CSL increased to 119 ± 32 mmHg and 90 ± 34 mmHg respectively within 5 m of ephedrine administration. The NES initial blood pressure measurement was 59/43 (50) (SAP/diastolic [MAP]) mmHg and increased to 80/51 (62) mmHg within 5 m. The initial HMS blood pressure was 79/68 (73) mmHg and increased to 99/78 (85) mmHg within 5 m following ephedrine administration. All patients recovered from anesthesia. These results support the efficacy of IV ephedrine for the treatment of anesthesia-associated hypotension in pinnipeds.

Understanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

In mammals, the photopigment melanopsin (Opn4) is found in a subset of retinal ganglion cells that serve light detection for circadian photoentrainment and pupil constriction (i.e., mydriasis). For a given species, the efficiency of photoentrainment and length of time that mydriasis occurs is determined by the spectral sensitivity and deactivation kinetics of melanopsin, respectively, and to date, neither of these properties have been described in marine mammals. Previous work has indicated that the absorbance maxima (λmax) of marine mammal rhodopsins (Rh1) have diversified to match the available light spectra at foraging depths. However, similar to the melanopsin λmax of terrestrial mammals (~480 nm), the melanopsins of marine mammals may be conserved, with λmax values tuned to the spectrum of solar irradiance at the water’s surface. Here, we investigated the Opn4 pigments of 17 marine mammal species inhabiting diverse photic environments including the Infraorder Cetacea, as well as the Orders Sirenia and Carnivora. Both genomic and cDNA sequences were used to deduce amino acid sequences to identify substitutions most likely involved in spectral tuning and deactivation kinetics of the Opn4 pigments. Our results show that there appears to be no amino acid substitutions in marine mammal Opn4 opsins that would result in any significant change in λmax values relative to their terrestrial counterparts. We also found some marine mammal species to lack several phosphorylation sites in the carboxyl terminal domain of their Opn4 pigments that result in significantly slower deactivation kinetics, and thus longer mydriasis, compared to terrestrial controls. This finding was restricted to cetacean species previously found to lack cone photoreceptor opsins, a condition known as rod monochromacy. These results suggest that the rod monochromat whales rely on extended pupillary constriction to prevent photobleaching of the highly photosensitive all-rod retina when moving between photopic and scotopic conditions.

Background Two transmission patterns of Sarcoptes scabiei in host mammal communities have been reported based on microsatellite-level genetic studies in the last two decades. While one involves restrictions among different host taxa, the other is associated with predator–prey interactions between different host taxa. In contrast to these observations, the present study reports a possible irregular case of transmission of S. scabiei between herbivorous Japanese serow and omnivorous Caniformia mammals in Japan, though under very weak predator–prey relationships. Methods DNA from 93 Sarcoptes mites isolated from omnivorous Caniformia (such as the domestic dog, raccoon dog, raccoon and Japanese marten), omnivorous Cetartiodactyla (wild boar) and herbivorous Cetartiodactyla (Japanese serow) in Japan were analyzed by amplifying nine microsatellite markers. Principal components analyses (PCA), Bayesian clustering analyses using STRUCTURE software, and phylogenetic analyses by constructing a NeighborNet network were applied to determine the genetic relationships among mites associated with host populations. Results In all the analyses, the genetic differentiation of Sarcoptes mites from wild boars and Japanese serows was observed. Conversely, considerably close genetic relationships were detected between Caniformia-derived and Japanese serow-derived mites. Because the predator–prey interactions between the omnivorous Caniformia and herbivorous Japanese serow are quite limited and epidemiological history shows at least a 10-year lag between the emergence of sarcoptic mange in Japanese serow and that in Caniformia, the transmission of S. scabiei from Caniformia to Japanese serow is highly suspected. Conclusions The close genetic relationships among mites beyond Host–taxon relationships and without obvious predator–prey interactions in Caniformia and Japanese serow deviate from previously reported S. scabiei transmission patterns. This type of cryptic relationship of S. scabiei populations may exist in local mammalian communities worldwide and become a risk factor for the conservation of the remnant and fragmented populations of wild mammals. Electronic supplementary material The online version of this article (10.1186/s13071-019-3630-5) contains supplementary material, which is available to authorized users.

The morphology of the skull contains considerable ecological information about a species, because the skull contains sensory organs that are used to look for food, compete for mates, or to migrate. Spotted seals (Phoca largha) and harbor seals (Phoca vitulina) are similar in body size and pelage color but differ in habitat use and reproductive biology. The current study aims to clarify differences in the shapes of skulls in the spotted and harbor seals using geometric morphometrics and to discuss whether ecological differences can explain morphological differences in skulls. First, we discovered that the age at which the shape of skulls stopped changing was 7 years in both species, using the linear-threshold model. Using a total of 75 landmarks, 54 individuals (25 spotted seals, 29 harbor seals) that were older than the age at which skulls stopped changing were correctly identified at a rate of 100%. The total of 75 landmarks was narrowed down to eight key landmarks that resulted in an identification accuracy rate of 100% using random forests. Of the eight landmarks, seven were related to feeding apparatus, indicated that the harbor seal had a broader mouth and mandible than the spotted seal. Because of both species were dietary generalists and classified as pierce feeders, we suggested that the different features in the shapes of their skulls were caused not only by differences in their feeding behavior but also other differences related to reproductive behavior.

Pinniped vibrissae are well-adapted to sensing in an aquatic environment, by being morphologically diverse and more sensitive than those of terrestrial species. However, it is both challenging and time-consuming to measure vibrissal sensitivity in many species. In terrestrial species, the infraorbital foramen (IOF) area is associated with vibrissal sensitivity and increases with vibrissal number. While pinnipeds are thought to have large IOF areas, this has not yet been systematically measured before. We investigated vibrissal morphology, IOF area, and skull size in 16 species of pinniped and 12 terrestrial Carnivora species. Pinnipeds had significantly larger skulls and IOF areas, longer vibrissae, and fewer vibrissae than the other Carnivora species. IOF area and vibrissal number were correlated in Pinnipeds, just as they are in terrestrial mammals. However, despite pinnipeds having significantly fewer vibrissae than other Carnivora species, their IOF area was not smaller, which might be due to pinnipeds having vibrissae that are innervated more. We propose that investigating normalized IOF area per vibrissa will offer an alternative way to approximate gross individual vibrissal sensitivity in pinnipeds and other mammalian species. Our data show that many species of pinniped, and some species of felids, are likely to have strongly innervated individual vibrissae, since they have high values of normalized IOF area per vibrissa. We suggest that species that hunt moving prey items in the dark will have more sensitive and specialized vibrissae, especially as they have to integrate between individual vibrissal signals to calculate the direction of moving prey during hunting.

Alzheimer’s disease (AD) is characterized by the accumulation of amyloid-β (Aβ) as senile plaques and cerebral amyloid angiopathy, and hyperphosphorylated tau (hp-tau) as neurofibrillary tangles in the brain. The AD-related pathology has been reported in several non-human animals, and most animals develop only the Aβ or tau pathology. We herein describe the Aβ and hp-tau pathology in the brains of aged pinniped species (seal, sea lion, and walrus). Molecular analyses revealed that the sequence of pinniped Aβ was identical to that of human Aβ. Histopathological examinations detected argyrophilic plaques composed of Aβ associated with dystrophic neurites in the cerebral cortex of aged pinnipeds. Astrogliosis and microglial infiltration were identified around Aβ plaques. Aβ deposits were observed in the blood vessel walls of the meninges and cerebrum. Pinniped tau protein was physiologically subjected to alternative splicing at exons 2, 3, and 10, and presented as five isoforms: two 3-repeat tau isoforms (1N3R, 2N3R) and three 4-repeat tau isoforms (0N4R, 1N4R, 2N4R); 0N3R tau isoform was absent. Histopathological examinations revealed argyrophilic fibrillar aggregates composed of hp-tau in the neuronal somata and neurites of aged pinniped brains. Few hp-tau aggregates were found in oligodendrocytes and microglia. Biochemically, hp-tau of the 3-repeat and 4-repeat isoforms was detected in brain sarkosyl-insoluble fractions. Aβ and hp-tau both predominantly accumulated in the neocortex, particularly the frontal cortex. Furthermore, the activation of GSK-3β was detected within cells containing hp-tau aggregates, and activated GSK-3β was strongly expressed in cases with severe hp-tau pathologies. The present results suggest that, in association with Aβ deposition, the activation of GSK-3β contributes to hp-tau accumulation in pinniped brains. Here, we report that pinniped species naturally accumulate Aβ and tau with aging, similar to the human AD pathology.

The gut microbiota may modulate the disposition and toxicity of environmental contaminants within a host but, conversely, contaminants may also impact gut bacteria. Such contaminant-gut microbial connections, which could lead to alteration of host health, remain poorly known and are rarely studied in free-ranging wildlife. The polar bear (Ursus maritimus) is a long-lived, wide-ranging apex predator that feeds on a variety of high trophic position seal and cetacean species and, as such, is exposed to among the highest levels of biomagnifying contaminants of all Arctic species. Here, we investigate associations between mercury (THg; a key Arctic contaminant), diet, and the diversity and composition of the gut microbiota of polar bears inhabiting the southern Beaufort Sea, while accounting for host sex, age class and body condition. Bacterial diversity was negatively associated with seal consumption and mercury, a pattern seen for both Shannon and Inverse Simpson alpha diversity indices (adjusted R2 = 0.35, F1,18 = 8.00, P = 0.013 and adjusted R2 = 0.26, F1,18 = 6.04, P = 0.027, respectively). No association was found with sex, age class or body condition of polar bears. Bacteria known to either be involved in THg methylation or considered to be highly contaminant resistant, including Lactobacillales, Bacillales and Aeromonadales, were significantly more abundant in individuals that had higher THg concentrations. Conversely, individuals with higher THg concentrations showed a significantly lower abundance of Bacteroidales, a bacterial order that typically plays an important role in supporting host immune function by stimulating intraepithelial lymphocytes within the epithelial barrier. These associations between diet-acquired mercury and microbiota illustrate a potentially overlooked outcome of mercury accumulation in polar bears.

Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/1999-4915/13/11/2180 En este artículo de investigación también participan: Manuel Arbelo, Antonio Fernández, Daniel García-Párraga y José Manuel Sánchez-Vizcaíno. Este artículo pertenece al número especial "Ecology of Virus Emergence from Wildilfe". 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 freeranging 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.

The Mediterranean monk seal (Monachus monachus) is a flagship species for marine conservation, but important aspects of its life history remain unknown. Concerns over imminent extinction motivated a nuclear DNA study of the species in its largest continuous subpopulation in the eastern Mediterranean Sea. Despite recent evidence of partial subpopulation recovery, we demonstrate that there is no reason for complacency, as the species still shares several traits that are characteristic of a critically endangered species: Mediterranean monk seals in the eastern Mediterranean survive in three isolated and genetically depauperate population clusters, with small effective population sizes and high levels of inbreeding. Our results indicated male philopatry over short distances, which is unexpected for a polygynous mammal. Such a pattern may be explained by the species’ unique breeding behavior, in which males defend aquatic territories near breeding sites, while females are often forced to search for new pupping areas. Immediate action is necessary to reverse the downward spiral of population decline, inbreeding accumulation and loss of genetic diversity. We propose concrete conservation measures for the Mediterranean monk seal focusing on reducing anthropogenic threats, increasing the population size and genetic diversity, and thus improving the long-term prospects of survival.

Campylobacter pinnipediorum was described recently for isolates recovered from pinnipeds. The novel species was further split into 2 subspecies based on host and geography, with C. pinnipediorum subsp. pinnipediorum recovered from otariid seals in California (USA) and C. pinnipediorum subsp. caledonicus recovered from phocid seals in Scotland. We report details of the infections of 7 pinnipeds from which C. pinnipediorum was isolated: C. pinnipediorum subsp. caledonicus was isolated from 2 harbour seals Phoca vitulina and a single grey seal Halichoerus grypus, and C. pinnipediorum subsp. pinnipediorum was isolated from California sea lions Zalophus californianus. Six of the isolates were recovered from samples collected at post-mortem investigation. In 2 of the Scottish seals and in 3 of the California seals, C. pinnipediorum was the sole bacterial isolate recovered from abscesses present and suggests they may have resulted from conspecific or intraspecific bite wounds.

Although commonly recorded as onset responses, the auditory brainstem response (ABR) can also be elicited at stimulus offset. The offset ABR has not been extensively investigated in marine mammals. Three normal hearing (NH) and three hearing impaired (HI) dolphins were assessed while fully submerged in sea water. Stimulus spectrum, level, rise/fall time (RFT), and plateau duration were manipulated. Onset and offset ABR amplitude were quantified as the rms voltage 1-7 ms following stimulus onset or offset, respectively. For the same stimulus conditions, onset and offset responses were often larger for NH than HI dolphins, and offset responses were typically smaller than onset responses. For the level series, offset response amplitude typically increased with increasing stimulus level, although offset responses were not 3 dB above the noisefloor for 113-kHz tonebursts. Increasing RFT decreased onset and offset response amplitude. For the 40-kHz tonebursts, a RFT of 32 μs produced a large amplitude offset ABR in NH dolphins. Offset responses for 113-kHz tonebursts were 3 dB above the noisefloor at the shortest RFTs. Offset responses were largest for 4 ms duration stimuli (likely due to overlapping onset and offset response analysis windows), but otherwise, offset responses changed little with increasing duration.

Marine mammals endure extended breath-holds while performing active behaviors, which has fascinated scientists for over a century. It is now known that these animals have large onboard oxygen stores and utilize oxygen-conserving mechanisms to prolong aerobically supported dives to great depths, while typically avoiding (or tolerating) hypoxia, hypercarbia, acidosis and decompression sickness (DCS). Over the last few decades, research has revealed that diving physiology is underdeveloped at birth. Here, I review the postnatal development of the body's oxygen stores, cardiorespiratory system and other attributes of diving physiology for pinnipeds and cetaceans to assess how physiological immaturity makes young marine mammals vulnerable to disturbance. Generally, the duration required for body oxygen stores to mature varies across species in accordance with the maternal dependency period, which can be over 2 years long in some species. However, some Arctic and deep-diving species achieve mature oxygen stores comparatively early in life (prior to weaning). Accelerated development in these species supports survival during prolonged hypoxic periods when calves accompany their mothers under sea ice and to the bathypelagic zone, respectively. Studies on oxygen utilization patterns and heart rates while diving are limited, but the data indicate that immature marine mammals have a limited capacity to regulate heart rate (and hence oxygen utilization) during breath-hold. Underdeveloped diving physiology, in combination with small body size, limits diving and swimming performance. This makes immature marine mammals particularly vulnerable to mortality during periods of food limitation, habitat alterations associated with global climate change, fishery interactions and other anthropogenic disturbances, such as exposure to sonar.

BackgroundThe African wild dog (Lycaon pictus), an endangered canid native to southern and eastern Africa, is distinct among canids in being described as entirely tetradactyl and in its nomadic lifestyle and use of exhaustive predation to capture its prey instead of speed, strength, or stealth. These behavioral and morphological traits suggest a potentially unique set of adaptations.MethodsHere, we dissected the forelimbs of an adult maleL. pictusspecimen and performed detailed descriptions and quantitative analyses of the musculoskeletal anatomy.ResultsStatistical comparisons of muscle masses and volumes revealed thatL. pictushas relatively smaller wrist rotators (mm. pronator teres, pronator quadratus, supinator) than any other included carnivoran taxon, suggesting adaptive pressures for antebrachial stability over rotatory movement in the carpus ofL. pictus. While a complete digit I is absent inL. pictus, a vestigial first metacarpal was discovered, resulting in changes to insertions of mm. extensor digiti I et II, abductor (et opponens) digiti I and flexor digiti I brevis. Mm. anconeus, brachialis and flexor carpi ulnaris caput ulnare all have more extensive origins inL. pictusthan other canids suggesting an emphasis on posture and elbow stability. M. triceps brachii caput laterale has a larger origin inL. pictusand m. triceps brachii caput longum has an additional accessory head. Electromyographic studies have shown this muscle is active during the stance phase of trotting and galloping and is important for storing elastic energy during locomotion. We interpret these differences in size and attachments of muscles inL. pictusas adaptations for long distance running in this highly cursorial species, likely important for exhaustive predation. Absence of a full digit I inL. pictusmay increase speed and stride length; however, the retention of a vestigial digit permits the attachment of reduced pollical muscles which may provide additional stability and proprioception to the carpus.

The aim of underwater noise exposure criteria in a regulatory context is to identify at what received levels noise-induced effects are predicted to occur, so that those effects may be appropriately considered in an evaluation or mitigation context under the respective regulatory regime. Special emphasis has been given to hearing related impairment of marine mammals due to their high sensitivity to and reliance on underwater sound. Existing regulations of underwater noise show substantial qualitative and quantitative discrepancies. A dataset acquired during an experiment that induced temporary threshold shift (TTS) in a harbor porpoise (Phocoena phocoena) from Lucke, Siebert, Lepper, and Blanchet [(2009). J. Acoust. Soc. Am. 125, 4060-4070] was reanalyzed to see if various exposure criteria predicted TTS differently for high-frequency cetaceans. This provided an unambiguous quantitative comparison of predicted TTS levels for the existing noise exposure criteria used by regulatory bodies in several countries. The comparative evaluation of the existing noise exposure criteria shows substantial disagreement in the predicted levels for onset for auditory effects. While frequency-weighting functions evolved to provide a better representation of sensitivity to noise exposure when compared to measured results at the criteria's onset, thresholds remain the most important parameter determining a match between criteria and measured results.

This research was funded through a research grant from the Scottish Government as part of the Marine Mammal Scientific Support Program MMSS/002/15. A wide range of anthropogenic structures exist in the marine environment with the extent of these set to increase as the global offshore renewable energy industry grows. Many of these pose acute risks to marine wildlife; for example, tidal energy generators have the potential to injure or kill seals and small cetaceans through collisions with moving turbine parts. Information on fine scale behaviour of animals close to operational turbines is required to understand the likely impact of these new technologies. There are inherent challenges associated with measuring the underwater movements of marine animals which have, so far, limited data collection. Here, we describe the development and application of a system for monitoring the three-dimensional movements of cetaceans in the immediate vicinity of a subsea structure. The system comprises twelve hydrophones and software for the detection and localisation of vocal marine mammals. We present data demonstrating the systems practical performance during a deployment on an operational tidal turbine between October 2017 and October 2019. Three-dimensional locations of cetaceans were derived from the passive acoustic data using time of arrival differences on each hydrophone. Localisation accuracy was assessed with an artificial sound source at known locations and a refined method of error estimation is presented. Calibration trials show that the system can accurately localise sounds to 2m accuracy within 20m of the turbine but that localisations become highly inaccurate at distances greater than 35m. The system is currently being used to provide data on rates of encounters between cetaceans and the turbine and to provide high resolution tracking data for animals close to the turbine. These data can be used to inform stakeholders and regulators on the likely impact of tidal turbines on cetaceans. Publisher PDF

Infectious disease emergence has increased significantly over the last 30 years, with mass mortality events (MMEs) associated with epizootics becoming increasingly common. Factors influencing these events have been widely studied in terrestrial systems, but remain relatively unexplored in marine mammals. Infectious disease-induced MMEs (ID MMEs) have not been reported ubiquitously among marine mammal species, indicating that intrinsic (host) and/or extrinsic (environmental) ecological factors may influence this heterogeneity. We assess the occurrence of ID MMEs (1955-2018) across extant marine mammals (n = 129) in relation to key life-history characteristics (sociality, trophic level, habitat breadth) and environmental variables (season, sea surface temperature [SST] anomalies, El Nino occurrence). Our results show that ID MMEs have been reported in 14% of marine mammal species (95% CI 9%-21%), with 72% (n = 36; 95% CI 56%-84%) of these events caused predominantly by viruses, primarily morbillivirus and influenza A. Bacterial pathogens caused 25% (95% CI 14%-41%) of MMEs, with only one being the result of a protozoan pathogen. Overall, virus-induced MMEs involved a greater number of fatalities per event compared to other pathogens. No association was detected between the occurrence of ID MMEs and host characteristics, such as sociality or trophic level, but ID MMEs did occur more frequently in semiaquatic species (pinnipeds) compared to obligate ocean dwellers (cetaceans; χ2 = 9.6, p = .002). In contrast, extrinsic factors significantly influenced ID MMEs, with seasonality linked to frequency (χ2 = 19.85, p = .0002) and severity of these events, and global yearly SST anomalies positively correlated with their temporal occurrence (Z = 3.43, p = 2.7e-04). No significant association was identified between El Nino and ID MME occurrence (Z = 0.28, p = .81). With climate change forecasted to increase SSTs and the frequency of extreme seasonal weather events, epizootics causing MMEs are likely to intensify with significant consequences for marine mammal survival.

Southern elephant seal (SES) and Antarctic fur seal (AFS) are short Southern Ocean food web top predators and are spatial and temporal trend bioindicators of Antarctic Hg bioavailability. Hg, stable isotope composition (δ 13C and δ 15N) and trophic position (TP) regarding sex were determined using lanugo samples from Antarctic pinnipeds pups (SES n = 35 and AFS n = 11). Hg concentrations in over 50% of the SES pups (mean 5.9 ± 3.1 mg kg−1 dry wt.) are compatible with those found to cause neurologic damage to polar bears in the Arctic. No significant differences regarding sexes for SES or AFS are found based on mean Hg concentrations normalized by body weight. δ 15N values and TPs are similar among both species, indicating that gestating SES and AFS mothers feed at the same trophic level. Significantly different δ 13C values were found, indicating distinct feeding grounds for mothers belonging to both species when pup lanugo is formed in utero; while SES females like to feed in Antarctic waters, AFS females remain in sub-Antarctic waters. The differences in Hg and δ 13C observed for both species reflect not only contrasting feeding habits and anthropogenic Hg inputs, but also maternal foraging strategies.

The challenge of identifying cause of death in discarded bycaught marine mammals stems from a combination of the non-specific nature of the lesions of drowning, the complex physiologic adaptations unique to breath-holding marine mammals, lack of case histories, and the diverse nature of fishing gear. While no pathognomonic lesions are recognized, signs of acute external entanglement, bulging or reddened eyes, recently ingested gastric contents, pulmonary changes, and decompression-associated gas bubbles have been identified in the condition of peracute underwater entrapment (PUE) syndrome in previous studies of marine mammals. We reviewed the gross necropsy and histopathology reports of 36 cetaceans and pinnipeds including 20 directly observed bycaught and 16 live stranded animals that were euthanized between 2005 and 2011 for lesions consistent with PUE. We identified 5 criteria which present at significantly higher rates in bycaught marine mammals: external signs of acute entanglement, red or bulging eyes, recently ingested gastric contents, multi-organ congestion, and disseminated gas bubbles detected grossly during the necropsy and histologically. In contrast, froth in the trachea or primary bronchi, and lung changes (i.e. wet, heavy, froth, edema, congestion, and hemorrhage) were poor indicators of PUE. This is the first study that provides insight into the different published parameters for PUE in bycatch. For regions frequently confronted by stranded marine mammals with non-specific lesions, this could potentially aid in the investigation and quantification of marine fisheries interactions.

Modern pinnipeds (true and eared seals) employ two radically different swimming styles, with true seals (phocids) propelling themselves primarily with their hindlimbs, whereas eared seals (otariids) rely on their wing-like foreflippers.1,2 Current explanations of this functional dichotomy invoke either pinniped diphyly3-5 or independent colonizations of the ocean by related but still largely terrestrial ancestors.6-8 Here, we show that pinniped swimming styles form an anatomical, functional, and behavioral continuum, within which adaptations for forelimb swimming can arise directly from a hindlimb-propelled bauplan. Within phocids, southern seals (monachines) show a convergent trend toward wing-like, hydrodynamically efficient forelimbs used for propulsion during slow swimming, turning, bursts of speed, or when initiating movement. This condition is most evident in leopard seals, which have well-integrated foreflippers with little digit mobility, reduced claws, and hydrodynamic characteristics comparable to those of forelimb-propelled otariids. Using monachines as a model, we suggest that the last common ancestor of modern seals may have been hindlimb-propelled and aquatically adapted, thus resolving the apparent contradiction at the root of pinniped evolution.

Otaria flavescens (SASL) and Arctocephalus australis (SAFS) are endemic of South America. The aims were to assess Cd concentrations in red blood cells (RBC) and plasma from free living females of both species; and to establish metallothioneins (MT) levels in blood fractions and the possible relationship between MTs and Cd. Blood of fifteen SASL and eight SAFS females from Isla de Lobos were analyzed (years 2010–2011). All animals showed Cd levels above the detection limit. Cd concentrations on SAFS were higher than those of SASL, however, no significant differences were observed on metal concentrations between cell fractions by species. Metal levels were associated with a natural presence and ecological-trophic habits of the prey items. On SASL the MT concentrations between fractions were similar; whereas, SAFS plasma concentrations were higher than RBC. The results reported constitute the first information on Cd and MT blood levels in these species. Fil: Polizzi, Paula Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Romero, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Chiodi Boudet, Leila Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Ponce de León, A.. Ministerio de Ganadería, Agricultura y Pesca; Uruguay Fil: Medici, Sandra Karina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Laboratorio de Análisis Fares Taire; Argentina Fil: Costas, A.. Laboratorio de Análisis Fares Taire; Argentina Fil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Gerpe, Marcela Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

The ability of marine mammals to hunt prey at depth is known to rely on enhanced oxygen stores and on selective distribution of blood flow, but the molecular mechanisms regulating blood flow and oxygen transport remain unresolved. To investigate the molecular mechanisms that may be important in regulating blood flow, we measured concentration of nitrite and S-nitrosothiols (SNO), two metabolites of the vasodilator nitric oxide (NO), in the blood of 5 species of marine mammals differing in their dive duration: bottlenose dolphin, South American sea lion, harbor seal, walrus and beluga whale. We also examined oxygen affinity, sensitivity to 2,3-diphosphoglycerate (DPG) and nitrite reductase activity of the hemoglobin (Hb) to search for possible adaptive variations in these functional properties. We found levels of plasma and red blood cells nitrite similar to those reported for terrestrial mammals, but unusually high concentrations of red blood cell SNO in bottlenose dolphin, walrus and beluga whale, suggesting enhanced SNO-dependent signaling in these species. Purified Hbs showed similar functional properties in terms of oxygen affinity and sensitivity to DPG, indicating that reported large variations in blood oxygen affinity among diving mammals likely derive from phenotypic variations in red blood cell DPG levels. The nitrite reductase activities of the Hbs were overall slightly higher than that of human Hb, with the Hb of beluga whale, capable of longest dives, having the highest activity. Taken together, these results underscore adaptive variations in circulatory NO metabolism in diving mammals but not in the oxygenation properties of the Hb. The ability of marine mammals to hunt prey at depth is known to rely on enhanced oxygen stores and on selective distribution of blood flow, but the molecular mechanisms regulating blood flow and oxygen transport remain unresolved. To investigate the molecular mechanisms that may be important in regulating blood flow, we measured concentration of nitrite and S-nitrosothiols (SNO), two metabolites of the vasodilator nitric oxide (NO), in the blood of 5 species of marine mammals differing in their dive duration: bottlenose dolphin, South American sea lion, harbor seal, walrus and beluga whale. We also examined oxygen affinity, sensitivity to 2,3-diphosphoglycerate (DPG) and nitrite reductase activity of the hemoglobin (Hb) to search for possible adaptive variations in these functional properties. We found levels of plasma and red blood cells nitrite similar to those reported for terrestrial mammals, but unusually high concentrations of red blood cell SNO in bottlenose dolphin, walrus and beluga whale, suggesting enhanced SNO-dependent signaling in these species. Purified Hbs showed similar functional properties in terms of oxygen affinity and sensitivity to DPG, indicating that reported large variations in blood oxygen affinity among diving mammals likely derive from phenotypic variations in red blood cell DPG levels. The nitrite reductase activities of the Hbs were overall slightly higher than that of human Hb, with the Hb of beluga whale, capable of longest dives, having the highest activity. Taken together, these results underscore adaptive variations in circulatory NO metabolism in diving mammals but not in the oxygenation properties of the Hb.

OBJECTIVE To identify factors associated with keratopathy in captive pinnipeds and to provide guidance for preventive measures. ANIMALS 319 captive pinnipeds (229 otariids [sea lions and fur seals], 74 phocids [true seals], and 16 odobenids [walrus]) from 25 facilities. PROCEDURES Descriptive data collected from questionnaires completed by facilities and from medical records and physical examinations of pinnipeds were compiled and evaluated. Variables were assessed with χ2 tests of homogeneity to determine potential association with keratopathy, and variables with values of P ≤ 0.25 were inserted into the multivariable logistic regression model. RESULTS Results indicated that variables associated with significantly increased odds of keratopathy in captive pinnipeds included lighter or reflective pool color (OR, 2.11; 95% confidence interval [CI], 1.20 to 3.97), pool water salinity < 29 g/L (OR, 3.48; 95% CI, 1.89 to 6.56), and history of eye disease (OR, 3.30; 95% CI, 1.85 to 5.98), trauma (OR, 3.80; 95% CI, 1.72 to 8.89), and having been tested for leptospirosis (OR, 3.83; 95% CI, 1.54 to 10.26). However, odds of keratopathy decreased with UV index ≤ 6 (OR, 0.39; 95% CI, 0.2 to 0.72) and age < 20 years (OR, 0.32; 95% CI, 0.15 to 0.66). CONCLUSIONS AND CLINICAL RELEVANCE Findings indicated that odds of keratopathy in pinnipeds could be reduced by maintenance of pool water salinity ≥ 29 g/L and reduction of UV radiation exposure (eg, with adequate shade structures and use of darker, natural colors). Because UV radiation exposure is cumulative, even small attempts to reduce lifetime exposure to it could help control keratopathy in pinnipeds.

Nitric oxide (NO) is a potent vasodilator, which improves perfusion and oxygen delivery during tissue hypoxia in terrestrial animals. The vertebrate dive response involves vasoconstriction in select tissues, which persists despite profound hypoxia. Using tissues collected from Weddell seals at necropsy, we investigated whether vasoconstriction is aided by downregulation of local hypoxia signaling mechanisms. We focused on NO–soluble guanylyl cyclase (GC)-cGMP signaling, a well-known vasodilatory transduction pathway. Seals have a lower GC protein abundance, activity, and capacity to respond to NO stimulation than do terrestrial mammals. In seal lung homogenates, GC produced less cGMP (20.1 ± 3.7 pmol·mg protein−1·min−1) than the lungs of dogs (−80 ± 144 pmol·mg protein−1·min−1less than seals), sheep (−472 ± 96), rats (−664 ± 104) or mice (−1,160 ± 104, P < 0.0001). Amino acid sequences of the GC enzyme α-subunits differed between seals and terrestrial mammals, potentially affecting their structure and function. Vasoconstriction in diving Weddell seals is not consistent across tissues; perfusion is maintained in the brain and heart but decreased in other organs such as the kidney. A NO donor increased median GC activity 49.5-fold in the seal brain but only 27.4-fold in the kidney, consistent with the priority of cerebral perfusion during diving. Nos3 expression was high in the seal brain, which could improve NO production and vasodilatory potential. Conversely, Pde5a expression was high in the seal renal artery, which may increase cGMP breakdown and vasoconstriction in the kidney. Taken together, the results of this study suggest that alterations in the NO-cGMP pathway facilitate the diving response.

The U.S. Endangered Species Act (ESA) is a powerful environmental law protecting imperiled plants and animals, and a growing number of marine species have been protected under this law as extinction risk in the oceans has increased. Marine mammals and sea turtles comprise 38% of the 163 ESA-listed marine "species", which includes subspecies and distinct population segments, yet analyses of recovery trends after listing are lacking. Here we gathered the best available annual abundance estimates for geographically delimited populations of all 62 marine mammal and sea turtle species listed under the ESA. Of these, we chose representative populations of species that were listed before 2012, occur and reproduce in U.S. waters, and have data of sufficient quality and timespan for trend analyses. Thus, we quantitatively analyzed population trends, magnitude of population change, and recovery status for 23 and 8 representative populations of 14 marine mammal and 5 sea turtle species, respectively. Using generalized linear and non-linear models, we found that 18 marine mammal (78%) and 6 sea turtle (75%) populations significantly increased after listing; 3 marine mammal (13%) and 2 sea turtle (25%) populations showed non-significant changes; while 2 marine mammal (9%), but no sea turtle populations declined after ESA protection. Overall, the 24 populations that increased in abundance were from species listed for 20 years or more (e.g., large whales, manatees, and sea turtles). Conservation measures triggered by ESA listing such as ending exploitation, tailored species management, and fishery regulations, and other national and international measures, appear to have been largely successful in promoting species recovery, leading to the delisting of some species and to increases in most populations. These findings underscore the capacity of marine mammal and sea turtle species to recover from substantial geographical population declines when conservation actions are implemented in a timely and effective manner.

The protozoans Toxoplasma gondii and Sarcocystis spp. (Sarcocystidae: Apicomplexa) affect a wide variety of vertebrates. Both have been reported to infect pinnipeds, with impacts on health ranging from inapparent to fulminant disease and death. However, little is known regarding their infections and associated pathology in South American pinnipeds. We used histological techniques to survey for the presence of T. gondii and Sarcocystis spp. in 51 stranded pinnipeds from Brazil. Immunohistochemical and molecular assays were employed in those cases consistent with Sarcocystidae infection. T. gondii cysts were detected in the central nervous system and heart of a South American fur seal Arctocephalus australis, associated with meningoencephalitis, myocarditis and endocarditis, and confirmed by immunohistochemistry. Additionally, this animal presented Sarcocystis sp. cysts in brain and heart tissues. Four additional specimens-2 Subantarctic fur seals A. tropicalis, an Antarctic fur seal A. gazella and another South American fur seal-presented intrasarcoplasmic cysts compatible with Sarcocystis spp. in muscle samples. There was no inflammation associated with the Sarcocystis spp. tissue cysts and all cysts were negative for S. neurona immunohistochemistry. The B1 gene of T. gondii was amplified in the 5 pinnipeds infected by Sarcocystidae protozoans. To our knowledge, this is the first report of toxoplasmosis in wild South American pinnipeds and of Sarcocystis spp. in South American fur seals. Detection of terrestrial parasites in aquatic mammals could be an indicator of their presence in the marine environment.

Current climate trends resulting in rapid declines in sea ice and increasing water temperatures are likely to expand the northern geographic range and duration of favorable conditions for harmful algal blooms (HABs), making algal toxins a growing concern in Alaskan marine food webs. Two of the most common HAB toxins along the west coast of North America are the neurotoxins domoic acid (DA) and saxitoxin (STX). Over the last 20 years, DA toxicosis has caused significant illness and mortality in marine mammals along the west coast of the USA, but has not been reported to impact marine mammals foraging in Alaskan waters. Saxitoxin, the most potent of the paralytic shellfish poisoning toxins, has been well-documented in shellfish in the Aleutians and Gulf of Alaska for decades and associated with human illnesses and deaths due to consumption of toxic clams. There is little information regarding exposure of Alaskan marine mammals. Here, the spatial patterns and prevalence of DA and STX exposure in Alaskan marine mammals are documented in order to assess health risks to northern populations including those species that are important to the nutritional, cultural, and economic well-being of Alaskan coastal communities. In this study, 905 marine mammals from 13 species were sampled including; humpback whales, bowhead whales, beluga whales, harbor porpoises, northern fur seals, Steller sea lions, harbor seals, ringed seals, bearded seals, spotted seals, ribbon seals, Pacific walruses, and northern sea otters. Domoic acid was detected in all 13 species examined and had the greatest prevalence in bowhead whales (68%) and harbor seals (67%). Saxitoxin was detected in 10 of the 13 species, with the highest prevalence in humpback whales (50%) and bowhead whales (32%). Pacific walruses contained the highest concentrations of both STX and DA, with DA concentrations similar to those detected in California sea lions exhibiting clinical signs of DA toxicosis (seizures) off the coast of Central California, USA. Forty-six individual marine mammals contained detectable concentrations of both toxins emphasizing the potential for combined exposure risks. Additionally, fetuses from a beluga whale, a harbor porpoise and a Steller sea lion contained detectable concentrations of DA documenting maternal toxin transfer in these species. These results provide evidence that HAB toxins are present throughout Alaska waters at levels high enough to be detected in marine mammals and have the potential to impact marine mammal health in the Arctic marine environment.

Marine mammals are more exposed to mercury (Hg) than any others animals in the world. As many trace elements, Hg it is able to impair the brain function, which could be a cause of population decline. Nevertheless, these issues have been scarcely studied because of the technical and ethical difficulties. We conducted a systematic review about marine mammals’ brain exposition to Hg and other trace elements, and their neurotoxic effects. Information was scarce and the lack of standardization of nomenclature of brain structures, sample collecting and results presentation made it difficult to obtain conclusions. Hg was the most studied metal and toothed whales the most studied group. Despite being its target organ, brain accumulates lesser concentrations of Hg than other tissues as liver. We found a significant positive correlation between both organs’ burden (rho = 0.956 for cetaceans; rho = 0.756 for pinnipeds). Reported Hg values in brain of cetaceans (median 3.00 ppm ww) surpassed by one or two orders of magnitude those values found in other species as pinnipeds (median 0.33 ppm ww) or polar bears (median 0.07 ppm ww). Such values exceeded neurotoxicity thresholds. Although marine mammals ingest mostly the organic and more toxic form MeHg, different fractions of inorganic mercury can appear in brain, which could suggest some detoxification mechanisms. Other suggested mechanisms include Se–Hg interaction and liver sequestration. Although other elements are subjected to a rigid homeostatic control, appear in low concentrations or do not exert an important neurotoxic effect, they should be more studied to elucidate their neurotoxicity potential.

Based on anatomical measurements of refractive structures in the eye, the positions of focused images were computed for several groups of semiaquatic mammals: rodents, a nonpinniped semiaquatic carnivore (the sea otter), and pinniped carnivores (seals, sea lions, and the walrus). In semiaquatic rodents, eye optics enable emmetropia in the air but cause substantial hypermetropia in the water. In semiaquatic carnivores, there are several mechanisms for amphibious vision that focus images on the retina in both air and water. These mechanisms include the potential for a substantial change in the lens shape of sea otters and the presence of the corneal emmetropic window in pinnipeds. The results suggest that several groups of mammals that independently adapted to aquatic environments vary in how their visual systems adapted to aquatic vision.

There is growing concern about the spreading of human microorganisms in relatively untouched ecosystems such as the Antarctic region. For this reason, three pinniped species (Leptonychotes weddellii, Mirounga leonina and Arctocephalus gazella) from the west coast of the Antartic Peninsula were analysed for the presence of Escherichia spp. with the recovery of 158 E. coli and three E. albertii isolates. From those, 23 harboured different eae variants (α1, β1, β2, ε1, θ1, κ, ο), including a bfpA-positive isolate (O49:H10-A-ST206, eae-k) classified as typical enteropathogenic E. coli. Noteworthy, 62 of the 158 E. coli isolates (39.2%) exhibited the ExPEC status and 27 (17.1%) belonged to sequence types (ST) frequently occurring among urinary/bacteremia ExPEC clones: ST12, ST73, ST95, ST131 and ST141. We found similarities >85% within the PFGE-macrorrestriction profiles of pinniped and human clinic O2:H6-B2-ST141 and O16:H5/O25b:H4-B2-ST131 isolates. The in silico analysis of ST131 Cplx genomes from the three pinnipeds (five O25:H4-ST131/PST43-fimH22-virotype D; one O16:H5-ST131/PST506-fimH41; one O25:H4-ST6252/PST9-fimH22-virotype D1) identified IncF and IncI1 plasmids and revealed high core-genome similarities between pinniped and human isolates (H22 and H41 subclones). This is the first study to demonstrate the worrisome presence of human-associated E. coli clonal groups, including ST131, in Antarctic pinnipeds. The sampling was funded by the Spanish Ministry of Science and Innovation (CGL-2005-25073-E/ANT and CTM2008-00570) and the Sea World & Bush Gardens Conservation Fund. Work at USC-LREC was supported by projects AGL2013-47852-R from the Ministerio de Economía y Competitividad (MINECO, Spain) and Fondo Europeo de Desarrollo Regional (FEDER); AGL2016-79343-R from the Agencia Estatal de Investigación (AEI, Spain) and FEDER; PI16/01477 from Plan Estatal de I + D + I 2013-2016, Instituto de Salud Carlos III (ISCIII), Subdirección General de Evaluación y Fomento de la Investigación, and FEDER; CN2012/303 and ED431C 2017/57 from the Consellería de Cultura, Educación e Ordenación Universitaria, (Xunta de Galicia) and FEDER. We would like to thank the military personnel at the Spanish Antarctic Base “Gabriel de Castilla” for their help and assistance and the Marine Technology Unit (CSIC), the Spanish Navy’s Oceanographic Research Ship “Las Palmas” and the Unidad de Tecnología Marítima (UTM, CSIC) for logistics and transport. We also express our gratitude to J. Castro-Urda, F.T. García-Moreno, C. Rengifo-Herrera, S. Rojo-Montejo, I. Ferre, V. Navarro, M. Gómez-Bautista, T. Alvaro-Alvarez and J. Coello-Pérez for their invaluable help in the sample collection. A. Mora acknowledges the Ministerio de Educación, Cultura y Deporte (Spain) for the mobility grant for teachers and researchers from the Programa Estatal de Promoción del Talento y su Empleabilidad, Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–2016. Sí

Background Piroplasms are unicellular, tick-borne parasites. Among them, during the past decade, an increasing diversity of Babesia spp. has been reported from wild carnivores. On the other hand, despite the known contact of domestic and wild carnivores (e.g. during hunting), and a number of ixodid tick species they share, data on the infection of dogs with babesiae from other families of carnivores are rare. Methods In this study blood samples were collected from 90 dogs and five road-killed badgers. Ticks were also removed from these animals. The DNA was extracted from all blood samples, and from 33 ticks of badgers, followed by molecular analysis for piroplasms with PCR and sequencing, as well as by phylogenetic comparison of detected genotypes with piroplasms infecting carnivores. Results Eleven of 90 blood DNA extracts from dogs, and all five samples from badgers were PCR-positive for piroplasms. In addition to the presence of B. canis DNA in five dogs, sequencing identified the DNA of badger-associated “Babesia sp. Meles-Hu1” in six dogs and in all five badgers. The DNA of “Babesia sp. Meles-Hu1” occurred significantly more frequently in dogs often taken to forests (i.e. the preferred habitat of badgers in Hungary), than in dogs without this characteristic. Moreover, detection of DNA from this Babesia sp. was significantly associated with hunting dogs in comparison with dogs not used for hunting. Two PCR-positive dogs (in one of which the DNA of the badger-associated Babesia sp. was identified, whereas in the other the DNA of B. canis was present) showed clinical signs of babesiosis. Engorged specimens of both I. canisuga and I. hexagonus were collected from badgers with parasitaemia, but only I. canisuga contained the DNA of “Babesia sp. Meles-Hu1”. This means a significant association of the DNA from “Babesia sp. Meles-Hu1” with I. canisuga. Phylogenetically, “Babesia sp. Meles-Hu1” belonged to the “B. microti” group. Conclusions This is the first detection of the DNA from a badger-associated Babesia sp. in dogs, one of which also showed relevant clinical signs. Based on the number of dogs with blood samples containing the DNA of “Babesia sp. Meles-Hu1” in this study (i.e. exceeding the number of B. canis-positives), these findings should not be regarded as isolated cases. It is assumed that dogs, which are used for hunting or frequently visit forests, are more likely to be exposed to this piroplasm, probably as a consequence of infestation with I. canisuga from badgers or from the burrows of badgers. The above results suggest that “Babesia sp. Meles-Hu1” should be added to the range of piroplasms, which are naturally capable of infecting hosts from different families of Caniformia.

A sphincter on the inferior vena cava can protect the heart of a diving mammal from overload when elevated abdominal pressures increase venous return, yet sphincters are reported incompetent or absent in some cetacean species. We previously hypothesized that abdominal pressures are elevated and pulsatile in fluking cetaceans, and that collagen is deposited on the diaphragm according to pressure levels to resist deformation. Here we tested the hypothesis that cetaceans generating high abdominal pressures need a more robust sphincter than those generating low pressures. We examined diaphragm morphology in seven cetacean and five pinniped species. All odontocetes had morphologically similar sphincters despite large differences in collagen content, and mysticetes had muscle that could modulate caval flow. These findings do not support the hypothesis that sphincter structure correlates with abdominal pressures. To understand why a sphincter is needed, we simulated the impact of oscillating abdominal pressures on caval flow. Under low abdominal pressures, simulated flow oscillated with each downstroke. Under elevated pressures, a vascular waterfall formed, greatly smoothing flow. We hypothesize cetaceans maintain high abdominal pressures to moderate venous return and protect the heart while fluking, and use their sphincters only during low-fluking periods when abdominal pressures are low. We suggest pinnipeds, which do not fluke, maintain low abdominal pressures. Simulations also showed retrograde oscillations could be transmitted upstream from the cetacean abdomen and into the extradural veins, with potentially adverse repercussions for the cerebral circulation. We propose that locomotion-generated pressures have influenced multiple aspects of the cetacean vascular system.

Acanthocephalans, cestodes, and some species of nematodes acquire nutrients from the lumen contents in the gastrointestinal (GI) tract of their definitive host. These parasites are exposed to toxicants, such as mercury (Hg), through passive or active feeding mechanisms; therefore, the focus of this study was to determine if there is an effect of parasites on the dietary availability of total mercury (THg) within piscivorous pinniped hosts. THg concentrations ([THg]) in selected host tissues, parasites, and GI lumen contents from 22 California sea lions (Zalophus californianus), 15 ringed seals (Phoca hispida), and 4 spotted seals (Phoca largha) were determined. Among all pinnipeds, [THg] in acanthocephalans of the large intestine were significantly higher than concentrations in other samples (host lumen contents, other parasites and host intestinal wall), irrespective of location within the host GI tract. δ15N values of parasites depended both on parasite group and location within the GI tract. δ15N values were consistently higher in parasites inhabiting the large intestine, compared to elsewhere in the GI tract, for both sea lions and seals. δ13C values in parasites did not differ significantly from host GI tissues. Based on both [THg] and stable isotope values, parasites are likely affecting the Hg bioavailability within the GI lumen contents and host tissues, and toxicant-parasite interactions appear to depend on both parasitic taxon as well as their location within the host intestine.

One of the most widely recognized effects of intense noise exposure is a noise-induced threshold shift—an elevation of hearing thresholds following cessation of the noise. Over the past twenty years, as concerns over the potential effects of human-generated noise on marine mammals have increased, a number of studies have been conducted to investigate noise-induced threshold shift phenomena in marine mammals. The experiments have focused on measuring temporary threshold shift (TTS)—a noise-induced threshold shift that fully recovers over time—in marine mammals exposed to intense tones, band-limited noise, and underwater impulses with various sound pressure levels, frequencies, durations, and temporal patterns. In this review, the methods employed by the groups conducting marine mammal TTS experiments are described and the relationships between the experimental conditions, the noise exposure parameters, and the observed TTS are summarized. An attempt has been made to synthesize the major findings across experiments to provide the current state of knowledge for the effects of noise on marine mammal hearing.

Seabirds and pinnipeds play an important role in biogeochemical cycling by transferring nutrients from aquatic to terrestrial environments. Indeed, soils rich in animal depositions have generally high organic carbon, nitrogen and phosphorus contents. Several studies have assessed bacterial diversity in Antarctic soils influenced by marine animals; however most have been conducted in areas with significant human impact. Thus, we chose Cape Shirreff, Livingston Island, an Antarctic Specially Protected Area designated mainly to protect the diversity of marine vertebrate fauna, and selected sampling sites with different types of animals coexisting in a relatively small space, and where human presence and impact are negligible. Using 16S rRNA gene analyses through massive sequencing, we assessed the influence of animal concentrations, via their modification of edaphic characteristics, on soil bacterial diversity and composition. The nutrient composition of soils impacted by Antarctic fur seals and kelp gulls was more similar to that of control soils (i.e. soils without visible presence of plants or animals), which may be due to the more active behaviour of these marine animals compared to other species. Conversely, the soils from concentrations of southern elephant seals and penguins showed greater differences in soil nutrients compared to the control. In agreement with this, the bacterial communities of the soils associated with these animals were most different from those of the control soils, with the soils of penguin colonies also possessing the lowest bacterial diversity. However, all the soils influenced by the presence of marine animals were dominated by bacteria belonging to Gammaproteobacteria, particularly those of the genus Rhodanobacter. Therefore, we conclude that the modification of soil nutrient composition by marine vertebrates promotes specific groups of bacteria, which could play an important role in the recycling of nutrients in terrestrial Antarctic ecosystems.

Internal pressures change throughout a cetacean's body during swimming or diving, and uneven pressures between the thoracic and abdominal compartments can affect the cardiovascular system. Pressure differentials could arise from ventral compression on each fluke downstroke or by a faster equilibration of the abdominal compartment with changing ambient ocean pressures compared with the thoracic compartment. If significant pressure differentials do develop, we would expect the morphology of the diaphragm to adapt to its in vivo loading. Here, we tested the hypothesis that significant pressure differentials develop between the thoracic and abdominal cavities in diving cetaceans by examining diaphragms from several cetacean and pinniped species. We found that: (1) regions of cetacean diaphragms possess subserosal collagen fibres that would stabilize the diaphragm against craniocaudal stretch; (2) subserosal collagen covers 5–60% of the thoracic diaphragm surface, and area correlates strongly with published values for swimming speed of each cetacean species (P

We characterize Brucella infection in a wild southern sea otter ( Enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. This otter stranded twice along the central California coast, US over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. Ultimately the otter was euthanized due to severe, progressive neurologic disease. Necropsy and postmortem radiographs revealed chronic, severe osteoarthritis spanning the proximal interphalangeal joint of the left hind fifth digit. Numerous coccobacilli within the joint were strongly positive on Brucella immunohistochemical labelling, and Brucella sp. was isolated in pure culture from this lesion. Sparse Brucella-immunopositive bacteria were also observed in the cytoplasm of a pulmonary vascular monocyte, and multifocal granulomas were observed in the spinal cord and liver on histopathology. Findings from biochemical characterization, 16S ribosomal DNA, and bp26 gene sequencing of the bacterial isolate were identical to those from marine-origin brucellae isolated from cetaceans and phocids. Although omp2a gene sequencing revealed 100% homology with marine Brucella spp. infecting pinnipeds, whales, and humans, omp2b gene sequences were identical only to pinniped-origin isolates. Multilocus sequence typing classified the sea otter isolate as ST26, a sequence type previously associated only with cetaceans. Our data suggest that the sea otter Brucella strain represents a novel marine lineage that is distinct from both Brucella pinnipedialis and Brucella ceti. Prior reports document the zoonotic potential of the marine brucellae. Isolation of Brucella sp. from a stranded sea otter highlights the importance of wearing personal protective equipment when handling sea otters and other marine mammals as part of wildlife conservation and rehabilitation efforts.

During independent diagnostic screenings of otariid seals in California (USA) and phocid seals in Scotland (UK), Campylobacter-like isolates, which differed from the established taxa of the genus Campylobacter, were cultured from abscesses and internal organs of different seal species. A polyphasic study was undertaken to determine the taxonomic position of these six isolates. The isolates were characterized by 16S rRNA gene and AtpA sequence analysis and by conventional phenotypic testing. The whole-genome sequences were determined for all isolates, and the average nucleotide identity (ANI) was determined. The isolates formed a separate phylogenetic clade, divergent from all other taxa of the genus Campylobacter and most closely related to Campylobactermucosalis. Although all isolates showed 100 % 16S rRNA gene sequence homology, AtpA and ANI analyses indicated divergence between the otariid isolates from California and the phocid isolates from Scotland, which warrants subspecies status for each clade. The two subspecies could also be distinguished phenotypically on the basis of catalase activity. This study shows clearly that the isolates obtained from pinnipeds represent a novel species within the genus Campylobacter, for which the name Campylobacter pinnipediorum sp. nov. is proposed. Within this novel species, the Californian isolates represent a separate subspecies, for which the name C. pinnipediorum subsp. pinnipediorum subsp. nov. is proposed. The type strain for both this novel species and subspecies is RM17260T (=LMG 29472T=CCUG 69570T). The Scottish isolates represent another subspecies, for which the name C. pinnipediorum subsp. caledonicus subsp. nov. is proposed. The type strain of this subspecies is M302/10/6T (=LMG 29473T=CCUG 68650T).

Objective To assess whether corneal lesions in stranded pinnipeds were associated with viral infections, and to identify the potential pathogen(s) associated with the lesions. Animals studied Twenty-nine California sea lions (Zalophus californianus), 18 northern elephant seals (Mirounga angustirostris), and 34 Pacific harbor seals (Phoca vitulina richardsii). Procedure DNA and RNA were extracted from ocular swabs, corneal tissue, and aqueous humor and screened for herpesvirus, adenovirus, poxvirus, and calicivirus families by PCR. Results The results indicated a high overall prevalence of viruses, with adenoviruses and herpesviruses detected in all three host species. Three novel adenoviruses (PhAdV-1, PhAdV-2, OtAdV-2) and two novel herpesviruses (PhHV-6, OtHV-4) were detected. There were no statistical differences in the prevalence of viral infection or coinfection among groups of individuals with or without corneal lesions, nor were lesion type, onset, or presence of concurrent disease significantly associated with a viral infection. Conclusions The results suggested that viral presence in ocular tissues was common, not significantly associated with ocular disease and thus should not preclude release of an otherwise healthy animal. We could not confirm a correlation of virus presence with lesion due to the high percentage of virus-positive, clinically normal animals. This implied that seals and sea lions can have ocular tissues infected with several viruses without having readily evident associated lesions. This difficulty in correlating viral presence, particularly herpesviruses, with ocular lesions was also a common finding in studies with terrestrial species and highlighted the difficulty of confirming a virus as a primary pathogen in ocular lesions.

Interspecies transmission may play a key role in the evolution and ecology of influenza A viruses. The importance of marine mammals as hosts or carriers of potential zoonotic pathogens such as highly pathogenic H5 and H7 influenza viruses is not well understood. The fact that influenza viruses are some of the few zoonotic pathogens known to have caused infection in marine mammals, evidence for direct transmission of influenza A virus H7N7 subtype from seals to man, transmission of pandemic H1N1 influenza viruses to seals and also limited evidence for long-term persistence of influenza B viruses in seal populations without significant genetic change, makes monitoring of influenza viruses in marine mammal populations worth being performed. In addition, such monitoring studies could be a great tool to better understand the ecology of influenza viruses in nature.

We document the first associations of two recently described species of Pasteurellaceae bacteria with lesions in wild pinnipeds in rehabilitation. Samples were collected from nine lesions in four California sea lions (Zalophus californianus) and two Pacific harbor seals (Phoca vitulina) during necropsy or admission examinations at a rehabilitation facility in northern California. Seven Pasteurellaceae isolates were identified using phenotypic tests and partial rpoB gene sequencing. Six strains of Otariodibacter oris were isolated from California sea lions. Otariodibacter oris was isolated in pure culture from four abscesses, an affected lymph node, and a bone lesion consistent with osteomyelitis. Otariodibacter oris was also cultured with Arcanobacterium phocae and β-hemolytic streptococci. A pure culture of Bisgaardia genomospecies 1 was obtained from an abscess in a harbor seal. This is the first time, to our knowledge, that O. oris has been associated with infection. Isolation of these bacteria in pure culture from abscesses and osteomyelitis strongly indicates a pathogenic potential of this organism. Likewise, the isolation of Bisgaardia genomospecies 1 in pure culture from an abscess in a harbor seal implies causality.

Studies on marine mammals can inform our understanding of the environmental health of the ocean. To evaluate the potential for changes in antimicrobial resistance, we analyzed a database spanning 2004-2010 that consisted of bacterial isolate identity and antimicrobial sensitivity for stranded pinnipeds in the Northwest Atlantic. Samples (n = 170) from treated animals yielded 310 bacterial isolates representing 24 taxa. We evaluated changes in antimicrobial class resistance from 2004 to 2010 for eight taxa. Escherichia coli displayed a significant increase in resistance to several antimicrobial classes. Other taxa displayed significant increases in resistance to aminoglycosides, and/or fluoroquinolones. In addition, we observed a significant increase in multiple antimicrobial resistance in cultures from untreated animals. These results demonstrate an increase in resistance among common bacterial pathogens of marine mammals over a time span of 6 years.

Auditory sensitivity in pinnipeds is influenced by the need to balance efficient sound detection in two vastly different physical environments. Previous comparisons between aerial and underwater hearing capabilities have considered media-dependent differences relative to auditory anatomy, acoustic communication, ecology, and amphibious life history. New data for several species, including recently published audiograms and previously unreported measurements obtained in quiet conditions, necessitate a re-evaluation of amphibious hearing in pinnipeds. Several findings related to underwater hearing are consistent with earlier assessments, including an expanded frequency range of best hearing in true seals that spans at least six octaves. The most notable new results indicate markedly better aerial sensitivity in two seals (Phoca vitulina and Mirounga angustirostris) and one sea lion (Zalophus californianus), likely attributable to improved ambient noise control in test enclosures. An updated comparative analysis alters conventional views and demonstrates that these amphibious pinnipeds have not necessarily sacrificed aerial hearing capabilities in favor of enhanced underwater sound reception. Despite possessing underwater hearing that is nearly as sensitive as fully aquatic cetaceans and sirenians, many seals and sea lions have retained acute aerial hearing capabilities rivaling those of terrestrial carnivores.

The prevalence of Bartonella species was investigated among wild carnivores of the suborder Caniformia, including 15 Japanese badgers (Meles anakuma), 8 Japanese martens (Martes melampus), 2 Japanese weasels (Mustela itatsi), 1 Siberian weasel (Mustela sibirica), 171 raccoon dogs (Nyctereutes procyonoides), and 977 raccoons (Procyon lotor) in Japan. Bartonella bacteria were isolated from one Japanese badger (6.7%) and from one Japanese marten (12.5%); however, no Bartonella species was found in other representatives of Caniformia. Phylogenetic analysis was based on concatenated sequences of six housekeeping genes (16S rRNA, ftsZ, gltA, groEL, ribC, and rpoB) and sequence of the 16S–23S internal transcribed spacer region. The sequence analysis indicated that the isolate derived from the Japanese badger (strain JB-15) can represent a novel Bartonella species and the isolate from the Japanese marten (strain JM-1) was closely related to Bartonella washoensis. This is the first report on isolation of Bartonella from badger and marten.

Investigation of the effects of various cycles of compression and decompression on the alveolar volumes of the excised lungs of sea lions and dogs. The results obtained include the finding that, in comparison to dog lungs, sea lion lungs empty more completely on mild compression and much more completely on severe compression. These findings support Scholander's (1940) hypothesis that some marine mammals are protected from decompression sickness by cartilaginous reinforcement of the small airways which permits alveolar emptying during a dive, so isolating compressed gas from pulmonary capillary blood.