Narwhal Monodon Monoceros Research Articles

Alphaherpesvirus infection in a free-ranging narwhal Monodon monoceros from Arctic Canada.

We report the detection of an alphaherpesvirus infecting an adult female narwhal Monodon monoceros captured live during a tagging project in Tremblay Sound, Nunavut, Canada, in August 2018. The individual had 2 open wounds on the dorsum but appeared in good overall health. A blowhole swab was collected, and subsequent virus isolation was performed using a beluga whale primary cell line. Non-syncytial cytopathic effects were seen, in contrast to syncytial cytopathic effects described for monodontid alphaherpesvirus 1 (MoAHV1) isolates previously recovered from beluga whales Delphinapterus leucas from Alaska, USA, and the Northwest Territories, Canada. Next-generation sequencing was performed on a sequencing library generated from the DNA of the viral isolate and the analysis of the assembled contigs permitted the recovery of 6 genes, conserved in all members of the family Orthoherpesviridae, for downstream genetic and phylogenetic analyses. BLASTN (basic local alignment search tool, searching nucleotide databases using a nucleotide query) analyses of the narwhal herpesvirus conserved genes showed the highest nucleotide identities to MoAHV1, ranging between 88.5 and 96.8%. A maximum likelihood phylogenetic analysis based on concatenation of the 6 conserved herpesviruses amino acid alignments revealed the narwhal herpesvirus (NHV) to be the closest relative to MoAHV1, forming a clade within the subfamily Alphaherpesvirinae, genus Varicellovirus. NHV is the first alphaherpesvirus characterized from a narwhal and represents a new viral species, which we propose to be known as Varicellovirus monodontidalpha2. Further research is needed to determine the prevalence and potential clinical impacts of this alphaherpesvirus infection in narwhals.

Narwhals react to ship noise and airgun pulses embedded in background noise.

Anthropogenic activities are increasing in the Arctic, posing a threat to niche-conservative species with high seasonal site fidelity, such as the narwhal Monodon monoceros. In this controlled sound exposure study, six narwhals were live-captured and instrumented with animal-borne tags providing movement and behavioural data, and exposed to concurrent ship noise and airgun pulses. All narwhals reacted to sound exposure with reduced buzzing rates, where the response was dependent on the magnitude of exposure defined as 1/distance to ship. Buzzing rate was halved at 12 km from the ship, and whales ceased foraging at 7–8 km. Effects of exposure could be detected at distances > 40 km from the ship.At only a few kilometres from the ship, the received high-frequency cetacean weighted sound exposure levels were below background noise indicating extreme sensitivity of narwhals towards sound disturbance and demonstrating their ability to detect signals embedded in background noise. The narwhal's reactions to sustained disturbance may have a plethora of consequences both at individual and population levels. The observed reactions of the whales demonstrate their auditory sensitivity but also emphasize, that anthropogenic activities in pristine narwhal habitats needs to be managed carefully if healthy narwhal populations are to be maintained.

Китообразные Баренцева моря: фауна и состояние популяций в начале XXI века

Комплексные научно-исследовательские работы, ежегодно проводимые Полярным филиалом ВНИРО (ПИНРО имени Н. М. Книповича) в Баренцевом море, позволяют получать актуальную информацию о распределении и встречаемости морских млекопитающих, в частности китообразных, которые являются важнейшим звеном в экосистеме Мирового океана. В последние годы необходимость проведения мониторинга морских млекопитающих приобретает всё бόльшую актуальность в связи с изменением климата и повышением температуры морей и океанов, что может привести к смещению ареалов и даже к возможному исчезновению тех или иных видов. В настоящей работе обобщены результаты судовых учётов китообразных, выполненных Полярным филиалом ВНИРО в Баренцевом море в 2010–2019 гг., а также приведены ретроспективные данные по фауне усатых (Mysticeti) и зубатых (Odontoceti) китов. На основе материалов судовых исследований и с учётом сведений из литературных источников определён современный состав китообразных Баренцева моря, который в начале XXI века может быть представлен 16 видами китообразных из 7 семейств. Анализ материалов судовых учётов позволил определить статус пребывания морских млекопитающих в акватории моря и выявить частоту их встречаемости. Приведена численность популяций большинства видов усатых и зубатых китов, указаны наиболее вероятные места их встреч. По данным исследований, самым массовым, часто и круглогодично встречающимся видом определён беломордый дельфин Lagenorhynchus albirostris: на его долю приходится более 80 % от общего количества учтённых морских млекопитающих и около 50 % от всех встреченных китообразных. К постоянно присутствующим в акватории моря видам также отнесены белуха Delphinapterus leucas и обыкновенная морская свинья Phocoena phocoena, местá локализации которых приурочены преимущественно к прибрежной зоне Кольского полуострова. С мая по октябрь в акватории Баренцева моря регулярно встречаются виды, прибывающие сюда для нагула из других районов Атлантики, — малый полосатик Balaenoptera acutorostrata, финвал Balaenoptera physalus и горбач Megaptera novaeangliae. Крайне редко в западном секторе Российской Арктики можно увидеть нарвала Monodon monoceros и высоколобого бутылконоса Hyperoodon ampullatus.

Marine mammal hotspots in the Greenland and Barents Seas

Environmental change and increasing levels of human activity are threats to marine mammals in the Arctic. Identifying marine mammal hotspots and areas of high species richness are essential to help guide management and conservation efforts. Herein, space use based on biotelemetric tracking devices deployed on 13 species (ringed sealPusa hispida, bearded sealErignathus barbatus, harbour sealPhoca vitulina, walrusOdobenus rosmarus, harp sealPagophilus groenlandicus, hooded sealCystophora cristata, polar bearUrsus maritimus, bowhead whaleBalaena mysticetus, narwhalMonodon monoceros, white whaleDelphinapterus leucas, blue whaleBalaenoptera musculus, fin whaleBalaenoptera physalusand humpback whaleMegaptera novaeangliae; total = 585 individuals) in the Greenland and northern Barents Seas between 2005 and 2018 is reported. Getis-OrdGi* hotspots were calculated for each species as well as all species combined, and areas of high species richness were identified for summer/autumn (Jun-Dec), winter/spring (Jan-May) and the entire year. The marginal ice zone (MIZ) of the Greenland Sea and northern Barents Sea, the waters surrounding the Svalbard Archipelago and a few Northeast Greenland coastal sites were identified as key marine mammal hotspots and areas of high species richness in this region. Individual hotspots identified areas important for most of the tagged animals, such as common resting, nursing, moulting and foraging areas. Location hotspots identified areas heavily used by segments of the tagged populations, including denning areas for polar bears and foraging areas. The hotspots identified herein are also important habitats for seabirds and fishes, and thus conservation and management measures targeting these regions would benefit multiple groups of Arctic animals.

Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

Abstract Global biotic and abiotic threats, particularly from pervasive human activities, are progressively pushing large, apex carnivorous mammals into the functional role of mesopredator. Hunters are now becoming the hunted. Despite marked impacts on these animals and the ecosystems in which they live, little is known about the physiological repercussions of this role downgrading from ultimate to penultimate predator. Here we examine how such ecological role reversals alter the physiological processes associated with energy expenditure, and ultimately the cost of survival during peak performance. Taxonomic group, preferred habitat and domestication affected the capacity of the oxygen pathway to support high levels of aerobic performance by carnivorous mammals. Fear responses associated with anthropogenic threats also impacted aerobic performance. Allometric trends for three energetic metrics [maximum oxygen consumption, field metabolic rates (FMRs) and the cost per stride or stroke], showed distinct trends in aerobic capacity for different evolutionary lineages of mammalian predators. Cursorial canids that chase down prey demonstrated the highest relative maximum oxygen consumption rates (10–25 times resting levels) and FMRs, while ambush predators (i.e. felids) and diving marine mammals had aerobic capacities that were similar to or lower than sedentary domestic mammals of comparable size. The maximum energetic cost of performance for apex predators depended on whether the animals were hunters or the hunted. Escape responses were exceptionally costly for marine (narwhal Monodon monoceros) and terrestrial (mountain lion Puma concolor) locomotor specialists, as well as semi‐aquatic (polar bear Ursus maritimus) species; all showed a nearly two‐fold increase in peak energy expenditure when avoiding threats. As the duration and frequency of threats to wild species continue to grow, cumulative energetic costs are becoming more apparent. In view of this, attention to the energy demands of apex predators will provide vital predictive power to anticipate mismatches between a species' functional design and human‐induced pressures, and allow for the development of conservation strategies based on how species are built to survive. A free Plain Language Summary can be found within the Supporting Information of this article.

Updates on Cyamidae (Crustacea: Amphipoda): redescriptions of Cyamus monodontis Lütken, 1870 and Cyamus nodosus Lütken, 1861, a new species of Isocyamus, and new host records for Syncyamus ilheusensis Haney, De Almeida and Reis, 2004

ABSTRACTSpecimens of cyamids were collected from fresh cetacean carcasses from Brazil, Iceland and New Caledonia. Identifications were based on literature and comparative material. Redescriptions based on the type series of Cyamus monodontis and Cyamus nodosus collected from narwhal Monodon monoceros are proposed, and lectotypes and paralectotypes are designated. A new species of Isocyamus was described herein, Isocyamus indopacetus sp. nov., which is characterised by the maxilliped with outer plate and two spine-like processes on the bases of gills. This is the first record of a cyamid parasitising the Longman’s beaked whale (Indopacetus pacificus) from New Caledonia. An updated key to Isocyamus is presented herein. Syncyamus ilheusensis is registered for the first time for the melon-headed whale Peponocephala electra and from the Clymene’s dolphin Stenella clymene from Ceará, Brazil.www.zoobank.org/urn:lsid:zoobank.org:pub:451A4857-9CFC-4C81-AF70-8DFD0D7CEB16

Complete mitochondrial genome of the beluga whale Delphinapterus leucas (Cetacea: Monodontidae)

The beluga whale Delphinapterus leucas (Mammalia: Cetacea: Monodontidae) is a small, toothed, Arctic and sub-Arctic cetacean threatened by human activities and environmental contamination. Herein, we report the first complete mitochondrial genome sequence of D. leucas, comprising 16,386 bp encoding the typical set of 37 mitochondrial genes, one replication origin, and a putative control region. It exhibits the classic vertebrate mitochondrial gene arrangement and demonstrated the highest similarity with the mitochondrial genome of the narwhal Monodon monoceros, a member of the only other extant genus in the Monodontidae family. Phylogenetic analysis using the 35 available Odontoceti (toothed whale) mitochondrial genomes clustered D. leucas with M. monoceros, with a tree topology that accorded well with traditional and recent molecular taxonomies. These data will provide information fundamental to conservation genetic studies of this endangered Arctic whale.

Differences in dive behaviour among the world’s three narwhal Monodon monoceros populations correspond with dietary differences

Differences in dive behaviour among the world’s three narwhal Monodon monoceros populations correspond with dietary differences

Life in the lead: extreme densities of narwhals Monodon monoceros in the offshore pack ice

There is a paucity of information on abundance, densities, and habitat selection of nar- whals Monodon monoceros in the offshore pack ice of Baffin Bay, West Greenland, despite the criti- cal importance of winter foraging regions and considerable sea ice declines in the past decades. We conducted a double-platform visual aerial survey over a narwhal wintering ground to obtain pack ice densities and develop the first fully corrected abundance estimate using point conditional mark- recapture distance sampling. Continuous video recording and digital images taken along the track- line allowed for in situ quantification of winter narwhal habitat and for the estimation of fine-scale narwhal habitat selection and habitat-specific sighting probabilities. Abundance at the surface was estimated at 3484 (coefficient of variation (CV) = 0.46) including whales missed by observers. The fully corrected abundance of narwhals was 18 044 (CV = 0.46), or approximately one-quarter of the entire Baffin Bay population. The narwhal wintering ground surveyed (~9500 km 2 ) had 2.4 to 3.2% open water based on estimates from satellite imagery (NASA Moderate Resolution Imaging Spectro- radiometer) and 1565 digital photographic images collected on the trackline. Thus, the ~18 000 nar- whals had access to 233 km 2 of open water, resulting in an average density of ~77 narwhals km -2 open water. Narwhal sighting probability near habitats with 50% open water, suggesting narwhals select optimal foraging areas in dense pack ice regardless of open water availability. This study pro- vides the first quantitative ecological data on densities and habitat selection of narwhals in pack ice foraging regions that are rapidly being altered with climate change.

The impacts of climate change on marine mammals: early signs of significant problems

Climate change is now known to be affecting the oceans. It is widely anticipated that impacts on marine mammals will be mediated primarily via changes in prey distribution and abundance and that the more mobile (or otherwise adaptable) species may be able to respond to this to some extent. However, the extent of this adaptability is largely unknown. Meanwhile, within the last few years direct observations have been made of several marine mammal populations that illustrate reactions to climate change. These observations indicate that certain species and populations may be especially vulnerable, including those with a limited habitat range, such as the vaquita Phocoena sinus, or those for which sea ice provides an important part of their habitat, such as narwhals Monodon monoceros, bowhead Balaena mysticetus and beluga Delphinapterus leucas whales and polar bears Ursus maritimus. Similarly, there are concerns about those species that migrate to feeding grounds in polar regions because of rapidly changing conditions there, and this includes many baleen whale populations. This review highlights the need to take projected impacts into account in future conservation and management plans, including species assessments. How this should be done in an adequately precautionary manner offers a significant challenge to those involved in such processes, although it is possible to identify at this time at least some species and populations that may be regarded as especially vulnerable. Marine ecosystems modellers and marine mammal experts will need to work together to make such assessments and conservation plans as robust as possible.

Head morphology in perinatal dolphins: A window into phylogeny and ontogeny

In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes.

Deep-diving by narwhals Monodon monoceros: differences in foraging behavior between wintering areas?

Variation in resource selection among sub-populations may elucidate differences in fit- ness and life history strategies. Specifically for top marine predators, differences in movements and behavior may result from responses to variation in a patchy, dynamic environment. Satellite-linked time-depth recorders (SLTDRs) were used to examine differences in narwhal Monodon monoceros diving behavior and habitat selection among 3 sub-populations in Canada and West Greenland (n = 16 individuals). The number of dives to different depths and time allocation within the water column was investigated in 3 seasons, with a focus on 2 discrete wintering grounds in Baffin Bay. Diving parameters were calculated from binned dive data and analyzed using repeated-measures mixed models accounting for temporal autocorrelation and individual variability. The number of surface dives (0 to 50 m) and time at the surface declined between summer and winter. Clear differences were observed between 2 wintering grounds. Whales occupying one wintering ground spent most of their time diving to between 200 and 400 m (25 dives per day, SE 3), confirmed by both depth and temperature recording tags. In contrast, narwhals in a separate wintering ground spent less time at shallow depths and most of their time diving to at least 800 m (13 to 26 dives per day, SE 1 to 3). A model of occupancy time at depth showed that whales making multiple daily deep dives spent over 3 h at > 800 m (SD 0.6) and traveled 13 min (SD 1) per round trip to reach this depth. Whales diving to between 200 and 400 m spent approximately 2.5 h (SD 0.4) at this depth, traveling 5 min per round trip. The observed differences in time allocation and dive behavior indicate local variation between the 2 wintering grounds in the Baffin Bay ecosystem.

Dependence of mechanical properties on fibre angle in narwhal tusk, a highly oriented biological composite

The successful modelling of the mechanical properties of mineralized tissues depends critically on the knowledge of the off-axis behaviour of individual unidirectional lamellae. Information on this is lacking. In this work we attempt to rectify the situation. Young's modulus, measured in bending and tension, and the tensile strength and ultimate strain to failure of the dentine of the narwhal Monodon monoceros, were determined on specimens that had almost unidirectional fibres, whose direction differed considerably from specimen to specimen. Modulus and strength decreased steadily with the degree of off-angle loading, falling to about 45% of maximum for modulus, and 35% of maximum for strength. Ultimate strain showed a less uniform behaviour, and remained remarkebly high at large angles. Differences in mechanical behaviour were not related to the very small differences in mineral content measured between specimens. These findings have strong implications for modelling the anisotropic behaviour of bone, because dentine is very much like bone in most important respects. Predictions using classical composite theory are reasonably satisfactory, as long as the mineral crystals are assumed to be platelets, not rods.

The mechanical design of the tusk of the narwhal (Monodon nonoceros: Cetacea)

The mechanical properties of the tissues of the tusk of a narwhal Monodon monoceros, their histological arrangement, and the gross anatomy of the tusk were examined. The histology of the tusk shows various toughening mechanisms. The tusk tissues are of low stiffness, but are very tough, suiting the tusks for loading on impact, but not for longitudinal loading. These mechanical properties suggest the possible functions of the tusk, namely to be long in order to be sexually attractive, while being tough in order to withstand ‘testing’ blows from other males.

Polar bear attack on a juvenile narwhal

A juvenile female narwhal Monodon monoceros landed at Pond Inlet had several sets of scratches on the posterior part of the body. They were probably made by a polar bear Ursus maritimus in the course of an unsuccessful attack. A successful attack on a young calf has been reported. Polar bears catch beluga (Delphinapterus leucas), and the narwhal is of similar size and habits, but polar bear predation on narwhal is less well documented.

The mechanical properties of the dentine and cement of the tusk of the narwhal Monodon monoceros compared with those of other mineralized tissues

Values for Young's modulus of elasticity, ultimate and yield stresses, ultimate and yield strains, work under the stress-strain curve and work of fracture were obtained from tensile and bending tests on specimens of narwhal tusk dentine and cement, femoral bone from young and mature cattle, and reindeer antler. Compared with the cattle bone the narwhal tissues had low Young's moduli, low yield stresses, rather low ultimate stresses and high ultimate strains. In all these properties they were similar to reindeer antler. The calcium content and hardness of the narwhal tissues were compared with those of human and cattle dental tissues. The narwhal dentine was considerably softer and less mineralized than human and cattle dentine. Human cementum was softer and less mineralized than cattle cementum, and was like narwhal cementum. In general, the mechanical properties of the narwhal tusk tissues were as would be expected from their mineral content, except that the stiffness of the cementum was low. It is likely that narwhal dentine is not very similar to human and cattle dentine in its mechanical properties.

An ultrastructural and fluorescence histochemical investigation of the innervation of retial arteries in Monodon monoceros.

In this study, the innervation of cerebrally related retial arteries in the narwhal Monodon monoceros was examined. Vessels were processed for the demonstration of adrenergic nerve endings by fluorescence histochemistry, and the results were confirmed by electron microscopy. Innervation of cerebrally related retial arteries was compared to that of a system situated in the haemal canal and supplying the tail. The retial arteries were poorly innervated. Adrenergic nerve endings, as indicated by fluorescence, occurred only in caudal portions of the spinal rete. Ultrastructurally, nerves were found in most retial vessels examined. However, except for arteries from caudal portions of the spinal rete, nerve numbers were few and because they occurred in outer layers of the adventitia were probably not functionally significant. In contrast, vessels in the haemal canal were well innervated. Nerve endings possessing neurotransmitter vesicles were adjacent to the smooth muscle cells. The cetacean rete mirabile, a system which supplies blood to the entire central nervous system, is apparently not under extensive nervous control, even though most reports suggest there is a relationship, possibly based on the presence of adjacent nerve trunks. Any vasomotor activity that does occur, possibly does so in response to catecholamines or other vasoactive agents circulating in the blood.