Evidence of hearing impairment was identified in a harbour porpoise (Phocoena phocoena) on the basis of scanning electron microscopy. In addition, based on histopathology and immunohistochemistry, ...there were signs of unrelated cerebral toxoplasmosis. The six-year old individual live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. The most significant gross lesion was multifocal necrosis and haemorrhage of the cerebrum. Histopathology of the brain revealed extensive necrosis and haemorrhage in the cerebrum with multifocal accumulations of degenerated neutrophils, lymphocytes and macrophages, and perivascular lymphocytic cuffing. The diagnosis of cerebral toxoplasmosis was confirmed by positive staining of protozoa with anti-Toxoplasma gondii antibodies. Tachyzoites were not observed histologically in any of the examined tissues. Ultrastructural evaluation of the inner ear revealed evidence of scattered loss of outer hair cells in a 290 µm long segment of the apical turn of the cochlea, and in a focal region of ~ 1.5 mm from the apex of the cochlea, which was compatible with noise-induced hearing loss. This is the first case of concurrent presumptive noise-induced hearing loss and toxoplasmosis in a free-ranging harbour porpoise from the North Sea.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In 1995, one of the largest outbreaks of human toxoplasmosis occurred in the Pacific Northwest region of North America. Genetic typing identified a novel Toxoplasma gondii strain linked to the ...outbreak, in which a wide spectrum of human disease was observed. For this globally-distributed, water-borne zoonosis, strain type is one variable influencing disease, but the inability of strain type to consistently explain variations in disease severity suggests that parasite genotype alone does not determine the outcome of infection. We investigated polyparasitism (infection with multiple parasite species) as a modulator of disease severity by examining the association of concomitant infection of T. gondii and the related parasite Sarcocystis neurona with protozoal disease in wild marine mammals from the Pacific Northwest. These hosts ostensibly serve as sentinels for the detection of terrestrial parasites implicated in water-borne epidemics of humans and wildlife in this endemic region. Marine mammals (151 stranded and 10 healthy individuals) sampled over 6 years were assessed for protozoal infection using multi-locus PCR-DNA sequencing directly from host tissues. Genetic analyses uncovered a high prevalence and diversity of protozoa, with 147/161 (91%) of our sampled population infected. From 2004 to 2009, the relative frequency of S. neurona infections increased dramatically, surpassing that of T. gondii. The majority of T. gondii infections were by genotypes bearing Type I lineage alleles, though strain genotype was not associated with disease severity. Significantly, polyparasitism with S. neurona and T. gondii was common (42%) and was associated with higher mortality and more severe protozoal encephalitis. Our finding of widespread polyparasitism among marine mammals indicates pervasive contamination of waterways by zoonotic agents. Furthermore, the significant association of concomitant infection with mortality and protozoal encephalitis identifies polyparasitism as an important factor contributing to disease severity in marine mammals.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A description and comparison of the four major methods available for studying conservation physiology of large whales, namely analysis of faecal, respiratory vapour, and skin/blubber biopsy samples, ...and photographs.
Large whales are subjected to a variety of conservation pressures that could be better monitored and managed if physiological information could be gathered readily from free-swimming whales. However, traditional approaches to studying physiology have been impractical for large whales, because there is no routine method for capture of the largest species and there is presently no practical method of obtaining blood samples from free-swimming whales. We review the currently available techniques for gathering physiological information on large whales using a variety of non-lethal and minimally invasive (or non-invasive) sample matrices. We focus on methods that should produce information relevant to conservation physiology, e.g. measures relevant to stress physiology, reproductive status, nutritional status, immune response, health, and disease. The following four types of samples are discussed: faecal samples, respiratory samples ('blow'), skin/blubber samples, and photographs. Faecal samples have historically been used for diet analysis but increasingly are also used for hormonal analyses, as well as for assessment of exposure to toxins, pollutants, and parasites. Blow samples contain many hormones as well as respiratory microbes, a diverse array of metabolites, and a variety of immune-related substances. Biopsy dart samples are widely used for genetic, contaminant, and fatty-acid analyses and are now being used for endocrine studies along with proteomic and transcriptomic approaches. Photographic analyses have benefited from recently developed quantitative techniques allowing assessment of skin condition, ectoparasite load, and nutritional status, along with wounds and scars from ship strikes and fishing gear entanglement. Field application of these techniques has the potential to improve our understanding of the physiology of large whales greatly, better enabling assessment of the relative impacts of many anthropogenic and ecological pressures.
Peribullar sinuses of harbour porpoises Phocoena phocoena are parasitized with high prevalence by the nematode Stenurus minor. The effect of S. minor on the hearing ability of this species is still ...undetermined. Here, we review the occurrence of S. minor in the inner ear of harbour porpoises recovered from strandings in the North and Baltic Seas. In particular, we present the results from ears collected in German and Danish waters from 2002 to 2016 and from Dutch waters from 2010 to 2016. While the prevalence of S. minor in pterygoid and peribullar sinuses and tympanic cavity was high in harbour porpoises (66.67% in our cases), its prevalence in the cochlea was rare. Only 1 case out of 129 analysed by either histology, electron microscopy or immunofluorescence showed the presence of a nematode parasite morphologically consistent with S. minor at the most basal portion of the right cochlea. This individual also had severe haemorrhage along the right cochlear spiral, which was likely caused by ectopic S. minor migration. Although this animal might have had impaired hearing in the right ear, it was otherwise in good body condition with evidence of recent feeding. These findings highlight the need to study the effect of parasites on hearing, and other pathological changes that might impair appropriate processing of acoustic information.
Killer whales (
Orcinus orca
) occur seasonally in the eastern Canadian Arctic during the summer months. Increasing killer whale sightings throughout the region, and incursions into areas where they ...have not historically been observed, have been linked with declining sea ice, which has raised questions about the potential ecological impacts of a greater killer whale presence in the Arctic. Here we report on four killer whales that died of starvation after overwintering in southeastern Hudson Bay. This incident is similar to two other reported killer whale ice entrapments in Hudson Bay in 2011 and 2013, which together exceed the incidence of such events over the previous century. The six confirmed, and up to 16 more assumed, deaths due to ice entrapments over the past decade almost certainly represent significant levels of mortality for the population(s) of killer whales in the Canadian Arctic. Ice entrapments of naïve killer whales exploring new Arctic territory may therefore offer a natural check on range expansions in the region, particularly in convoluted inland bays and inlets into which they pursue previously inaccessible prey, but fail to exit prior to ice formation.
The killer whale (
, Linnaeus, 1958) is the largest extant delphinid. Despite its worldwide distribution in the wild and in dolphinariums, its anatomy remains relatively poorly described. In the ...present study, we describe the detailed morphology of a plastinated killer whale heart. The gross description of the arteries and veins reaching the organ and its coronary vessels are reported. Additional endoscopy and CT (computed tomography) scanning were performed to provide extensive measurements of its parts. In many aspects, the killer whale heart conformed to other delphinid heart descriptions, including position, relative size and shape and specific features such as extensive papillary muscles, trabecular endocardium and
. These characteristics are representative of the delphinid family, suggesting that its functions and capacities are similar to that of other, smaller, dolphins and help understand the conditions in which these predators exert their remarkable physical performance necessary for their survival.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Defining baseline mortality and trends in wildlife populations is imperative to understand natural and anthropogenic threats to overall population health and improve conservation measures for ...species, particularly in geographically confined habitats. The Guadalupe fur seal Arctocephalus townsendi (GFS) is a threatened pinniped that ranges throughout the west coast of Mexico with sporadic dispersion to higher latitudes. Their breeding habitat is restricted to Guadalupe Island, Mexico, which is vulnerable to periodic and cyclic warming of the Northeast Pacific Ocean. The impacts of environmental change on GFS health and reproductive success at Guadalupe Island are poorly defined and the aim of this study was to establish baseline pup (GFS
n
) mortality rates and primary causes of death during the 2013-2016 breeding seasons at Guadalupe Island. Interannual mortality rates and causes of death were compared by year, breeding seasons and by geographic location. The highest mortality rate in GFS
n
was in 2015 (14.7%), followed by 2014 (8.2%), 2016 (6.7%) and 2013 (5.6%). The presumptive causes of mortality of GFS
n
were consistent with other published long term otariids health surveys and included: emaciation (49%), trauma (24%), infectious disease (8%), drowning (4%) stillbirth/perinatal mortality (4%) and undetermined (11%). However, in 2015 and coinciding with northeast Pacific marine heatwave in 2014-2016, emaciation accounted for 54% of GFS
n
mortality in contrast to 9% in 2013. For GFS
n
, terrestrial habitat may influence mortality rates and causes of mortality but like other marine predators, marine habitat features, such as an increase in sea surface temperature are associated with changes in maternal care, nutritional status and pups survival. Monitoring mortality rate and causes in GFS
n
at Guadalupe Island is crucial to establish baseline health trends, document potential impacts on species demographics and recruitment during marine heatwaves and potential consequences in population recovery.
The endangered Cook Inlet (Alaska, USA) stock of beluga whales Delphinapterus leucas declined 47% between 1994 and 1998, from an estimated 653 whales to 347 whales, with a continued decline to ...approximately 312 in 2012. Between 1998 and 2013, 164 known dead strandings were reported by the National Marine Fisheries Service. Only 38 of these animals, or 23% of the known stranded carcasses, were necropsied. Carcasses were found between April and October. The majority of animals necropsied were adults (n=25), followed by juveniles (n=6), calves (n=3), and aborted fetuses (n=4). Eight of the 11 mature females were pregnant, post-partum, or lactating. Many (82%) of these belugas were in moderate to advanced autolysis, which hampered determination of a cause of death (COD). Each animal had a single primary COD assigned within a broad set of categories. The CODs were unknown (29%), trauma (18%), perinatal mortality (13%), mass stranding (13%), single stranding (11%), malnutrition (8%), or disease (8%). Other disease processes were coded as contributory or incidental to COD. Multiple animals had mild to moderate verminous pneumonia due to Stenurus arctomarinus, renal granulomas due to Crassicauda giliakiana, and ulcerative gastritis due to Anisakis sp. Each stranding affords a unique opportunity to obtain natural history data and evidence of human interactions, and, by long-term monitoring, to characterize pathologies of importance to individual and population health.
Primary fungal diseases in marine mammals are rare. Mucormycosis, a disease caused by fungi of the order Mucorales, has been documented in few cetaceans and pinnipeds. In 2012, the first case of ...mucormycosis in the Pacific Northwest was documented in a dead stranded harbor porpoise (Phocoena phocoena) in Washington state. Since then, mucormycosis has been detected in a total of 21 marine mammals; fifteen harbor porpoises, five harbor seals (Phoca vitulina), and one southern resident killer whale (Orcinus orca). Infected animals were predominately found in the inland waters of Washington and British Columbia, and one harbor seal was recovered in northern Oregon. Fungal hyphae were detected histologically in a variety of tissues, including brain, lung, spleen, pancreas, kidneys, muscle, lymph nodes, and skin. Three fungal species were identified from seven cases by PCR screening or fungal culture; Rhizomucor pusillus (four cases), Lichtheimia corymbifera (two cases), and Cunninghamella bertholletiae. Underlying conditions such as emaciation, current or recent pregnancy, multisystemic parasitism, protozoal infection, and herpesvirus were found in several affected animals. Reasons for the appearance and subsequent increase of these fungal infections in marine mammals are unknown. The emergence of this disease as a source of marine mammal mortality in the Pacific Northwest is of particular concern for endangered southern resident killer whales that spend time in this region. Current population-level stressors such as insufficient prey, high levels of contaminants, and noise pollution, could predispose them to these fatal infections.
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