Beluga Whales Delphinapterus Leucas Research Articles

Blood Cell Morphology of the Beluga Whale <i>Delphinapterus leucas</i> (Pallas, 1776)

Clinical blood analysis, combined with cytomorphological examination is an important diagnostic tool for assessing the physiological state of animals. The cytomorphological features of blood cells have been described for terrestrial mammals, and well-illustrated veterinary atlases have been created, in which normal and pathological forms of animal blood cells are displayed. However, such information is virtually non-existent for marine mammals. In this article, we present the results of a study of the morphology of the blood cells of the beluga (also known as white) whale Delphinapterus leucas, obtained by supravital staining of blood smear preparations with brilliant cresyl blue, methylene blue, and utilizing the standard Romanowsky–Giemsa staining technique. We describe the main types of blood cells of marine mammals: erythrocytes, segmented neutrophils, eosinophils, monocytes, lymphocytes, band neutrophils, as well as rare basophils.

Possible occurrence of contact calls in all‐male groups of free‐ranging beluga whales

AbstractSocial toothed whales are known to produce specific vocalizations that may serve for individual or group recognition and maintaining cohesion among group members. In beluga whales Delphinapterus leucas, these vocalizations referred to as “contact calls” are relatively long duration, repeated stereotyped broadband sounds. Although these calls are thought to be critical in mother‐calf communication, they are utilized by individuals of different ages and sex. We investigated possible occurrence of contact calls in all‐male beluga groups from the White Sea, Russia. Among the vocalizations analyzed (n = 1169), a considerable proportion (58%) appeared to be potential contact calls. They were subjectively classified into 61 types of mostly complex broadband sounds combined with a narrow band element. The positive linear relationship (R2 = 0.90) between the number of unique call types identified in the recordings and the number of belugas observed in the research area suggests that the calls serve as individual signatures. Belugas tended to produce these calls in a series, with the intercall intervals between the same and different call types mainly >1 s and <1 s, respectively. This suggests that vocal exchange by individually distinctive calls, like those of captive belugas and some other social species, might take place. The current study provides more insight into contact call usage in wild belugas and may serve as a basis for long‐term monitoring of their seasonal occurrence, abundance, and site fidelity, as well as for investigating their social organization.

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.

Estimating reproductive and juvenile survival rates when offspring ages are uncertain: A novel multievent mark‐resight model with beluga whale case study

Abstract Understanding the survival and reproductive rates of a population is critical to determining its long‐term dynamics and viability. Mark‐resight models are often used to estimate these demographic rates, but estimation of survival and reproductive rates is challenging, especially for wide‐ranging, patchily distributed, or cryptic species. In particular, existing mark‐resight models cannot accommodate data from populations in which offspring remain with parents for multiple years, are not always detected, and cannot be aged with certainty. Here we describe a Bayesian multievent mark‐resight modelling framework that uses all available adult and adult‐offspring sightings (including sightings with older offspring of uncertain age) to estimate reproductive rates and survival rates of adults and juveniles. We extend existing multievent mark‐resight models that typically only incorporate adult breeding state uncertainty by additionally accounting for age uncertainty in unmarked offspring and uncertainty in the duration of the mother‐offspring association. We describe our model in general terms and with a simple illustrative example, then apply it in a more complex empirical setting using 13 years of photo‐ID data from a critically endangered population of beluga whales Delphinapterus leucas. We evaluated model performance using simulated data under a range of sample sizes, and adult and offspring detection rates. Applying our model to the beluga data yielded precise estimates for all demographic rates of interest (despite substantial uncertainty in calf ages), including nonbreeder survival and reproductive rates lower than in other beluga populations. Simulations suggested our model yields asymptotically unbiased parameter estimates with good precision and low bias even with moderate sample sizes and detection rates. This work represents an important new development in multievent mark‐resight modelling, allowing estimation of reproductive and juvenile survival rates for populations with extended adult—offspring associations and uncertain offspring ages (e.g. some marine mammals, elephants, bears, great apes, bats and birds). Our model facilitated estimation of robust demographic rates for an endangered beluga population that were previously inestimable (e.g. nonbreeder and juvenile survival, reproductive rate) and that will yield new insights into this population's continued decline.

Feces DNA analyses track the rehabilitation of a free-ranging beluga whale

Following the sudden appearance, and subsequent efforts to support the survival of a beluga whale (Delphinapterus leucas) speculated to have been previously trained off the coast of Norway, we investigate the animal’s ability to readapt to life in the wild. Dietary DNA (dDNA) analysis was used to assess diet throughout this rehabilitation process, and during a return to unassisted foraging and self-feeding. Metabarcoding of feces collected throughout this process, confirmed the diversification of the beluga whale’s diet to local prey. These findings are indicative of improved foraging behavior, and the ability of this individual to resume wild foraging following a period of dependency in managed care. New insight of digestion rates, and the time window during which prey detection through dDNA analysis is appropriate was also obtained. Beyond the case study presented here, we demonstrate the power of dDNA analysis as a non-intrusive tool to assess the diet of large mammals and track progress adapting to life in the wild following release from captivity and rehabilitation programs.

Dependence of the Testosterone Concentration in the Blood of Male Beluga Whales Delphinapterus leucas on the Age and Season

Dependence of the Testosterone Concentration in the Blood of Male Beluga Whales Delphinapterus leucas on the Age and Season

Congenital defects and herpesvirus infection in beluga whale Delphinapterus leucas calves from the Critically Endangered Cook Inlet population

Cook Inlet beluga whales (CIBs) Delphinapterus leucas are Critically Endangered and genetically distinct from other beluga populations in Alaska. CIBs are exposed to numerous natural and anthropogenic sources of mortality and morbidity. This study describes congenital defects observed in 2 CIB calves. The first case, an aborted fetus, was characterized by lack of a peduncle and flukes, anorectal and genitourinary dysgenesis, and probable biliary dysplasia. The second case, a male calf, had a perineal groove defect and suspected secondary peritonitis; it also had a systemic herpesvirus infection. Further studies are needed to determine if such defects are due to genetic mutation, infectious diseases, nutritional imbalances, or contaminant exposure.

Predation of archival tagged Dolly Varden, Salvelinus malma, reveals predator avoidance behaviour and tracks feeding events by presumed beluga whale, Delphinapterus leucas, in the Beaufort Sea

BackgroundWe report compelling evidence suggesting a predation event of a pop-up satellite archival tagged anadromous Dolly Varden (Salvelinus malma) by a marine mammal during summer in the Beaufort Sea based on abrupt changes in temperature and vertical movements. This observation provides insight on predator avoidance behaviour by Dolly Varden and the predator’s feeding frequency while the tag was ingested. Based on published distribution and ecology information, we presumed the predator was a beluga whale (Delphinapterus leucas). Supplemental satellite telemetry data from previously tagged Dolly Varden and beluga whales were used to determine the extent of spatial and vertical overlap between species in the area where predation occurred.ResultsPrior to the predation event, depths and temperatures occupied by the tagged Dolly Varden averaged 1.1 m and 3.1 °C, respectively. On July 7, 2020, depths remained shallow apart from a sudden dive to 12.5 m (16:45 UTC) followed by a precipitous increase in temperature from 4.4 to 27.1 °C (16:52 UTC) suggesting predation by an endotherm. Subsequent readings indicated the endotherm had a resting stomach temperature of 36.1 °C. Including the predation event, eight separate feeding events were inferred during the 20-h period the tag was ingested (before presumed regurgitation) based on subsequent declines in stomach temperatures (mean decline to 31.1 °C) that took an average of 24.1 min to return to resting temperature. The predator occupied mainly shallow depths (mean = 2.3 m), overlapping with tagged belugas that spent 76.9% of their time occupying waters ≤ 2.5 m when frequenting the area occupied by tagged Dolly Varden in the Canadian Beaufort Sea in July. Back-calculation based on tag drift and mean displacement by tagged belugas indicated the predation likely occurred west of the Mackenzie Delta.ConclusionOur findings provide new information on both anti-predator behaviour by, and marine predators of, Dolly Varden in the Beaufort Sea. We provide the first estimate of feeding frequency and stomach temperature recovery in a presumed wild beluga, and evidence for shallow foraging behaviour by belugas. Elucidating the likely predator and exploring the extent of overlap between Dolly Varden and beluga whales contributes towards knowledge on the trophic interactions in the Beaufort Sea.

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.

Cochlear apical morphology in toothed whales: Using the pairing hair cell-Deiters' cell as a marker to detect lesions.

The apex or apical region of the cochlear spiral within the inner ear encodes for low-frequency sounds. The disposition of sensory hair cells on the organ of Corti is largely variable in the apical region of mammals, and it does not necessarily follow the typical three-row pattern of outer hair cells (OHCs). As most underwater noise sources contain low-frequency components, we expect to find most lesions in the apical region of the cochlea of toothed whales, in cases of permanent noise-induced hearing loss. To further understand how man-made noise might affect cetacean hearing, there is a need to describe normal morphological features of the apex and document interspecific anatomic variations in cetaceans. However, distinguishing between apical normal variability and hair cell death is challenging. We describe anatomical features of the organ of Corti of the apex in 23 ears from five species of toothed whales (harbor porpoise Phocoena phocoena, spinner dolphin Stenella longirostris, pantropical spotted dolphin Stenella attenuata, pygmy sperm whale Kogia breviceps, and beluga whale Delphinapterus leucas) by scanning electron microscopy and immunofluorescence. Our results showed an initial region where the lowest frequencies are encoded with two or three rows of OHCs, followed by the typical configuration of three OHC rows and three rows of supporting Deiters' cells. Whenever two rows of OHCs were detected, there were usually only two corresponding rows of supporting Deiters' cells, suggesting that the number of rows of Deiters' cells is a good indicator to distinguish between normal and pathological features.

Influence of boat tourism on the behaviour of Solovetskiy beluga whales (Delphinapterus leucas) in Onega Bay, the White Sea

Abstract The influence of boat tourism on the beluga whale Delphinapterus leucas in the White Sea, Russia, was studied based on regular observations of belugas near the Solovetskiy Islands from 1995 to 2015. Changes in beluga behaviour, which were affected both by the distance between the boats and the whales and the character of boat activity (e.g. anchoring, drifting, or moving with the engine running) were observed. Boats following the belugas caused the greatest impact on the whales. This negative reaction was observed throughout all periods of observations. The results indicate the need to evaluate the potential long‐term, cumulative anthropogenic impact on beluga behaviour and the development of appropriate mitigation measures.

Seasonal distribution and foraging occurrence of Cook Inlet beluga whales based on passive acoustic monitoring

A paucity of information on the basic biology and ecology of Cook Inlet beluga whalesDelphinapterus leucasremains a decade after the species was listed as endangered in 2008. The causes of its continued decline remain unclear. This lack of knowledge limits our understanding of, and ability to manage, potential threats impeding the recovery of this endangered population. Seasonal distribution and foraging ecology, particularly during winter, are currently among the most basic gaps in knowledge. Therefore, we conducted a year-round passive acoustic monitoring program from 2008-2013, monitoring 13 locations within the belugas’ critical habitat. We identified seasonal occurrence patterns across years at most locations. Detections were higher in the upper inlet during summer, peaking in known concentration areas. The occurrence of whales in the upper inlet when ice coverage peaked during winter was more prevalent than previously suggested. We documented seasonal differences in foraging habitat preference, with foraging behavior more prevalent during summer, particularly near upper inlet rivers, than during winter. Foraging peaks coincided with the presence of different anadromous fish runs from spring to fall. Low levels of feeding activity in winter suggest a lack of feeding aggregation areas, feeding in non-monitored offshore waters, or increased effort on benthic prey. These results represent a substantial contribution to our knowledge of Cook Inlet beluga seasonal distribution and foraging ecology, which will strengthen conservation and management strategies and thus more effectively promote recovery of this endangered population.

Whale tear glands in the bowhead and the beluga whales: Source and function.

Orbital glands are found in many tetrapod vertebrates, and are usually separate structures, consisting of individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. There are few histochemical and immunhistochemical studies to date of these structures. In this study, we examined the orbital glandular region of both the bowhead whale (Balaena mysticetus: Mysticeti) and the beluga whale (Delphinapterus leucas: Odontoceti) using histological, histochemical, and immunohistochemical techniques. Histologically, in the bowhead, three glandular areas were noted (circumorbital, including Harderian and lacrimal poles), palpebral (midway in the lower eyelid), and rim (near the edge of the eyelid). In the beluga, there was only a large, continuous mass within the eyelid itself. Histochemical investigation suggests neither sexual dimorphism nor age-related differences, but both whales had two cell types freely intermingling with each other in all glandular masses. Large cells (cell type 1) were distended by four histochemically distinct intracellular secretory granules. Smaller cells (cell type 2) were not distended (fewer granules) and had two to three histochemically distinct intracellular secretory granules. The beluga orbital glands had additional lipid granules in cell type 1. Counterintuitively, both lipocalin and transferrin were localized to cell type 2 only. This intermingling of cell types is unusual for vertebrates in whom individual orbital glands usually have one cell type with one to two different secretory granules present. The heterogeneity of the orbital fluid produced by cetacean orbital glands implies a complex function, or series of functions, for these orbital glands and their role in producing the tear fluid.

ВАРИАБЕЛЬНОСТЬ СОДЕРЖАНИЯ СЫВОРОТОЧНОГО ТЕСТОСТЕРОНА У БЕЛУХ DELPHINAPTERUS LEUCAS РАЗНЫХ ВОЗРАСТОВ

Recently, the issues of a comprehensive study of the reproductive system of marine mammals, in particular the analysis of hormonal changes in the organism of cetaceans in the process of their growth and development has become urgent. In the present work, the content of serum testosterone in blood samples of male beluga whales Delphinapterus leucas was determined. The studies were carried out on belugas kept in semi-free conditions of an open-air marine enclosure complex in the Barents Sea. Venous blood samples were obtained from animals aged 5 to 10 years, while individuals under 7 years old were considered immature. A total of 5 belugas were examined, 43 samples were obtained. Blood sampling was carried out from the ventral or dorsal vein of the caudal fin using a vacuum blood sampling system in plastic vacuum tubes. The volume of the samples ranged from 3 to 12 ml of native blood. Blood serum for research was obtained by centrifuging the samples at 2000 rpm for 10-15 minutes. About 2.5-3 ml of serum was obtained from 8 ml of native blood. It was frozen, stored and transported to the laboratory at a temperature of -20 ° С. The testosterone content in the samples was determined by the method of heterogeneous enzyme-linked immunosorbent assay (ELISA). A comparative assessment of the concentration of this steroid hormone in young and mature animals showed a positive linear correlation between the level of testosterone secretion and the age of the animal. Studies have shown that the sexual maturity of male beluga whales occurs by the age of 8-10, when serum testosterone levels of 15 nmol / L or higher are reached.

Persistent Mü̈llerian duct syndrome in a beluga whale Delphinapterus leucas.

This case study describes a persistent Mü̈llerian duct syndrome (PMDS), a rare form of XY disorder of sex development (DSD), in a mature (>15 yr) beluga whale Delphinapterus leucas. The phenotypically and genetically male beluga whale had both Mü̈llerian (paramesonephric) and Wolffian (mesonephric) duct derivatives. A mild hydrometra was present. Gross and histological analyses indicated the testes were atrophied. Histopathologic findings in the testes also included fibrosis in addition to ductus deferens ductular dilation, epididymal ductular dilation, lymphoplasmacytic balanitis, uterine glandular atrophy, and endometrial fibrosis. DSDs are rarely reported in cetaceans, and PMDS has never been described in a cetacean.

Environmental drivers of beluga whale Delphinapterus leucas habitat use in the Mackenzie Estuary, Northwest Territories, Canada

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 626:209-226 (2019) - DOI: https://doi.org/10.3354/meps13011 Environmental drivers of beluga whale Delphinapterus leucas habitat use in the Mackenzie Estuary, Northwest Territories, Canada K. Scharffenberg1,*, D. Whalen2, M. Marcoux1,3, J. Iacozza4, G. Davoren1, L. Loseto1,4 1Dept of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada 2Natural Resources Canada, Geological Survey of Canada, Dartmouth, Nova Scotia B2Y 4A2, Canada 3Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, Manitoba R3T 2N6, Canada 4Dept of Environment & Geography, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada *Corresponding author: scharffk@myumanitoba.ca ABSTRACT: Understanding drivers of habitat use and selection of mobile species is critical for understanding the impacts of climate change and formulating management plans. Eastern Beaufort Sea beluga whales Delphinapterus leucas form large summering aggregations in the warm, fresh waters of the Mackenzie Estuary, Northwest Territories, Canada; however, the environmental factors driving spatial and temporal patterns of habitat use within the estuary are not fully understood. We used passive acoustic monitoring to record beluga presence during their summer aggregation (June-August) at known congregation areas and locations with unique oceanographic features in Kugmallit Bay in the Mackenzie River Estuary, while simultaneously recording environmental and oceanographic data. The effectiveness of hydrophones at determining beluga presence/absence was validated using shore-based observations. Multiple logistic regression was used to assess the influence of environmental conditions on presence/absence of belugas. Results indicate that temporal patterns of habitat use varied by location, and were influenced by environmental conditions such as temperature, salinity, and wind speed. Belugas did not frequent commonly used locations during periods with high-speed winds and moved farther into the estuary during periods of cold oceanic influxes. This study provides support for hypotheses that belugas use the location for moulting or to provide a thermal advantage for young belugas. This information can be used to inform decisions by northern communities and policy makers, thus aiding in management of the Beaufort Sea beluga population. KEY WORDS: Passive acoustic monitoring · Oceanography · Estuarine ecology · Arctic Full text in pdf format Supplementary material PreviousNextCite this article as: Scharffenberg K, Whalen D, Marcoux M, Iacozza J, Davoren G, Loseto L (2019) Environmental drivers of beluga whale Delphinapterus leucas habitat use in the Mackenzie Estuary, Northwest Territories, Canada. Mar Ecol Prog Ser 626:209-226. https://doi.org/10.3354/meps13011 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 626. Online publication date: September 12, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Adaptation processes in the auditory system of a beluga whale Delphinapterus leucas.

The effects of prolonged sound stimuli (tone pip trains) on evoked potentials (the rate following response, RFR) were investigated in a beluga whale. The stimuli (rhythmic tone pips) were of 64 kHz frequency at levels from 80 to 140 dB re 1 μPa. During stimulation, every 1000 ms stimulus level either was kept constant (the steady-state stimulation) or changed up/down by 20 or 40 dB. With such stimulus presentation manner, RFR amplitude varied as follows. (i) After a stimulus level increase, the response amplitude increased quickly and then decayed slowly. The more the level increased, the higher the response amplitude increased. (ii) After a stimulus level decrease, the response amplitude was suppressed and then recovered slowly. The more the level decreased, the stronger was the response suppression. (iii) At the end of the 1000 ms window, the response amplitude approached, but did not reach, the amplitude characteristic of the steady-state stimulation. As a result, both after a sound level increase and decrease, the responses were almost stabilized during an analysis time as short as 1 s. This stabilization is attributed to an adaptation process. RFR decay after initial increase could be approximated by an exponent with a time constant of 59.4 ±1.8 (standard error) ms; RFR recovery after initial decrease could be approximated by an exponent with a time constant of 139.2 ±9.9 ms.

Influence of the Background Noise on Recognition of Signals with a Complex Spectrum Structure in the Beluga Whale (Delphinapterus leucas).

The frequency resolving power of hearing (FRP) of the beluga whale Delphinapterus leucas was studied as dependent on influence of lasting low-intensity sounds (of the ultrasonic range from -20 to +10 dB). Testing of the spectrum ripple-phase reversal was used in conjunction with a noninvasive recording of auditory evoked potentials. FRP parameters were found to depend nonmonotonically on the intensity of the background noise. The resultant adaptation effects can be explained by the fact that, in response to the high-intensity signals, the auditory system sensitivity is reduced to the level optimal for analysis of these signals.

Biomarkers of the cholinergic and dopaminergic signaling pathways in Arctic beluga whales (Delphinapterus leucas): relationship to methylmercury and selenium

There are increasing concerns about potential neurotoxicity of chronic methylmercury (MeHg) exposure in Arctic wildlife and human populations. The relationships between mercury (Hg), MeHg, inorganic Hg (iHg), and selenium (Se) exposure, and neurochemical and molecular biomarkers in beluga whales (Delphinapterus leucas (Pallas, 1776)) were characterized. Samples were collected in 2008 (n = 20) and 2010 (n = 15) in the Canadian Arctic from hunter-harvested beluga whales. Total Hg concentrations in the temporal cortex and cerebellum were 21.0 ± 22.6 mg kg−1 dry weight (dw) and 14.9 ± 18.9 mg kg−1 dw, respectively. Monoamine oxidase (MAO) activity was predicted by MeHg and the molar ratio of total Hg to Se (Hg:Se, p < 0.05); MAO-A mRNA transcription levels were predicted by iHg and Se (p < 0.05). Muscarinic AChR binding was predicted by MeHg (p < 0.05) and Hg:Se molar ratio (p < 0.05), and mRNA transcription levels of mAChR m1 was predicted by the Hg:Se molar ratio (p < 0.05). These results suggest that the c...

Qualitative risk assessment of impact of Toxoplasma gondii on health of beluga whales, Delphinapterus leucas from the Eastern Beaufort Sea, Northwest Territories

In recent years, the protozoan parasite Toxoplasma gondii has increasingly been recognized in Arctic fauna, including beluga whales (Delphinapterus leucas) in the Eastern Beaufort Sea (EBS), Northw...