Publications

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anisakids (nematoda: anisakidae) from stomachs of northern fur seals (callorhinus ursinus) on st. paul island, alaska: parasitological and pathological analysis.anisakid nematodes parasitize the alimentary tracts of aquatic vertebrates, including northern fur seals (callorhinus ursinus) (nfs). the main purpose of this study was to estimate the prevalence, intensity, and species composition of anisakids in nfss on st. paul island, alaska, and to analyze changes in nfs infection with these nematodes during the last decades. the study was carried out on st. paul island, alaska, in july-august 2011-2013. stomachs of 443 humanely harvested nfs males were col ...201425216781
the cestode community in northern fur seals (callorhinus ursinus) on st. paul island, alaska.the diversity and ecology of cestodes from the northern fur seals, callorhinus ursinus (nfs), were examined using newly collected material from 756 humanely harvested subadult males between 2011 and 2014. nfss were collected from five different haul-outs on st. paul island, alaska. a total of 14,660 tapeworms were collected with a prevalence of 98.5% and intensity up to 107 cestodes per host (mean intensity 19.7 ± 16.5 sd). three species of tapeworms were found: adenocephalus pacificus (diphyllo ...201526101743
high morphological plasticity and global geographical distribution of the pacific broad tapeworm adenocephalus pacificus (syn. diphyllobothrium pacificum): molecular and morphological survey.the most important causative agent of human diphyllobothriosis in south america, diphyllobothrium pacificum, is transferred to the original genus adenocephalus nybelin, 1931; revised and redescribed on the basis of the evaluation of an extensive material collected mainly from northern fur seal, callorhinus ursinus, from st. paul island, alaska. detailed analysis of morphological and morphometrical data shows a high variability in most of the characteristics traditionally used in diagnosis of dip ...201526001974
tooth size variation in pinniped dentitions.it is contentious whether size variation among mammalian teeth is heterogeneous or homogeneous, whether the coefficient of variation is reliable, and whether the standard deviation of log-transformed data and the residual of standard deviation on mean variable size are useful replacements for the coefficient of variation. most studies of tooth size variation have been on mammals with complex-crowned teeth, with relatively little attention paid to taxa with simple-crowned teeth, such as pinnipedi ...201526317362
uridine diphosphate-glucuronosyltransferase (ugt) xenobiotic metabolizing activity and genetic evolution in pinniped species.there are various interspecies differences in xenobiotic-metabolizing enzymes. it is known that cats show slow glucuronidation of drugs such as acetaminophen and strong side effects due to the ugt1a6 pseudogene. recently, the ugt1a6 pseudogene was found in the northern elephant seal and otariidae was suggested to be ugt1a6-deficient. from the results of measurements of uridine diphosphate-glucuronosyltransferase (ugt) activity using liver microsomes, the steller sea lion, northern fur seal, and ...201526179383
stable isotope models predict foraging habitat of northern fur seals (callorhinus ursinus) in alaska.we developed models to predict foraging habitat of adult female northern fur seals (callorhinus ursinus) using stable carbon (δ13c) and nitrogen (δ15n) isotope values from plasma and red blood cells. binomial generalized linear mixed models were developed using blood isotope samples collected from 35 adult female fur seals on three breeding colonies in alaska during july-october 2006. satellite location and dive data were used to define habitat use in terms of the proportion of time spent or div ...201526030280
feeding kinematics and performance of basal otariid pinnipeds, steller sea lions and northern fur seals: implications for the evolution of mammalian feeding.feeding performance studies can address questions relevant to feeding ecology and evolution. our current understanding of feeding mechanisms for aquatic mammals is poor. therefore, we characterized the feeding kinematics and performance of five steller sea lions (eumetopias jubatus) and six northern fur seals (callorhinus ursinus). we tested the hypotheses that both species use suction as their primary feeding mode, and that rapid jaw opening was related to suction generation. steller sea lions ...201526449976
dental and temporomandibular joint pathology of the northern fur seal (callorhinus ursinus).skulls from 145 northern fur seals (callorhinus ursinus) were examined macroscopically according to predefined criteria. the museum specimens were acquired from strandings along the west coast of the usa between 1896 and 2008. seventy-one skulls (49.0%) were from male animals, 56 (38.6%) from female animals and 18 (12.4%) from animals of unknown sex. their age varied from juvenile to adult, with 58 adult animals (40.0%) and 87 juvenile animals (60.0%). the majority of teeth were available for ex ...201525824117
accelerometers identify new behaviors and show little difference in the activity budgets of lactating northern fur seals (callorhinus ursinus) between breeding islands and foraging habitats in the eastern bering sea.we tagged 82 lactating northern fur seals (callorhinus ursinus) with tri-axial accelerometers and magnetometers on two eastern bering sea islands (bogoslof and st. paul) with contrasting population trajectories. using depth data, accelerometer data and spectral analysis we classified time spent diving (30%), resting (~7%), shaking and grooming their pelage (9%), swimming in the prone position (~10%) and two types of previously undocumented rolling behavior (29%), with the remaining time (~15%) u ...201525807552
evaluation of the ability of northern fur seals to perceive and visually discriminate images under the conditions of sleep loss.this is the first study estimating the ability of sea mammals to perceive and analyze information under the conditions of an almost complete sleep deprivation.201526335972
two bacterial genera, sodalis and rickettsia, associated with the seal louse proechinophthirus fluctus (phthiraptera: anoplura).roughly 10% to 15% of insect species host heritable symbiotic bacteria known as endosymbionts. the lice parasitizing mammals rely on endosymbionts to provide essential vitamins absent in their blood meals. here, we describe two bacterial associates from a louse, proechinophthirus fluctus, which is an obligate ectoparasite of a marine mammal. one of these is a heritable endosymbiont that is not closely related to endosymbionts of other mammalian lice. rather, it is more closely related to endosym ...201626994086
prevalence of algal toxins in alaskan marine mammals foraging in a changing arctic and subarctic 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 m ...201628073526
fukushima derived radiocesium in subsistence-consumed northern fur seal and wild celery.in july 2014, our investigative team traveled to st. paul island, alaska to measure concentrations of radiocesium in wild-caught food products, primarily northern fur seal (callorhinus ursinus). the 2011 fukushima daiichi nuclear power plant accident released radiocesium into the atmosphere and into the western pacific ocean; other investigators have detected fukushima-derived radionuclides in a variety of marine products harvested off the western coast of north america. we tested two subsistenc ...201626630034
a novel gammaherpesvirus in northern fur seals (callorhinus ursinus) is closely related to the california sea lion (zalophus californianus) carcinoma-associated otarine herpesvirus-1.otarine herpesvirus 1 (othv1) is strongly associated with california sea lion (csl, zalophus californianus) urogenital carcinoma, the most common cancer documented in marine mammals. in addition to csl, othv1 has also been found in association with carcinoma in south american fur seals (arctocephalus australis), demonstrating it can infect related species. northern fur seals (nfs, callorhinus ursinus) are sympatric with csl, and copulation between these species has been observed; yet, there are ...201626555110
organohalogen contaminants and vitamins in northern fur seals (callorhinus ursinus) collected during subsistence hunts in alaska.during native subsistence hunts from 1987 to 2007, blubber and liver samples from 50 subadult male northern fur seals (callorhinus ursinus) were collected on st. paul island, alaska. samples were analyzed for legacy persistent organic pollutants (pops), recently phased-out/current-use pops, and vitamins. the legacy pops measured from blubber samples included polychlorinated biphenyl congeners, ddt (and its metabolites), chlorobenzenes, chlordanes, and mirex. recently phased-out/current-use pops ...201626142120
monoamine release during unihemispheric sleep and unihemispheric waking in the fur seal.our understanding of the role of neurotransmitters in the control of the electroencephalogram (eeg) has been entirely based on studies of animals with bilateral sleep. the study of animals with unihemispheric sleep presents the opportunity of separating the neurochemical substrates of waking and sleep eeg from the systemic, bilateral correlates of sleep and waking states.201626715233
characterization of species differences in xenobiotic metabolism in non-experimental animals.the ability to metabolize xenobiotics in organisms has a wide degree of variation among organisms. this is caused by differences in the pattern of xenobiotic bioaccumulation among organisms, which affects their tolerance. it has been reported in the veterinary field that glucuronidation (ugt) activity in cats, acetylation activity in dogs and sulfation (sult) activity in pigs are sub-vital in these species, respectively, and require close attention when prescribing the medicine. on the other han ...201728250318
contamination status and accumulation characteristics of heavy metals and arsenic in five seabird species from the central bering sea.seabirds are marine top predators and accumulate high levels of metals and metalloids in their tissues. contamination by metals in the highly productive offshore region has become a matter of public concern. it is home to 80% of the seabird population in the usa, 95% of northern fur seals (callorhinus ursinus), and major populations of steller sea lions (eumetopias jubatus), walruses (odobenus rosmarus) and whales. here, the concentrations of eight heavy metals (hg, cd, cr, co, ni, cu, zn and pb ...201728302954
developmental study of the monophyodont teeth in the northern fur seal (callorhinus ursinus). 20175264597
udp-glucuronosyltransferase (ugt) 2b subfamily interspecies differences in carnivores.udp-glucuronosyltransferases (ugts) are among the most important xenobiotic metabolizing enzymes that conjugate a wide range of chemicals. previous studies showed that felidae and pinnipedia species have very low ugt activities toward some phenolic compounds because of the ugt1a6 pseudogene and small numbers of ugt1a isozymes. in addition to the ugt1as, ugt2bs isozymes also conjugate various endogenous (e.g., estrogens, androgens, and bile acids) and exogenous compounds (opioids, nsaids, and env ...201728453659
activity-specific metabolic rates for diving, transiting, and resting at sea can be estimated from time-activity budgets in free-ranging marine mammals.time and energy are the two most important currencies in animal bioenergetics. how much time animals spend engaged in different activities with specific energetic costs ultimately defines their likelihood of surviving and successfully reproducing. however, it is extremely difficult to determine the energetic costs of independent activities for free-ranging animals. in this study, we developed a new method to calculate activity-specific metabolic rates, and applied it to female fur seals. we atta ...201728479996
normal hematology and serum chemistry of northern fur seals (callorhinus ursinus) in captivity.northern fur seals (callorhinus ursinus) are endemic to the north pacific ocean. they were hunted for their fur and became endangered in the late 1800s, but their populations recovered following the introduction of protection laws. recently, populations have been decreasing again, although the reasons are unclear. for individuals that are bred and reared in captivity as part of ex situ conservation projects, details of blood characteristics are essential to ensure good health. however, the norma ...201728906018
sleep in the northern fur seal.the pattern of sleep in the fur seal, a semiaquatic pinniped, has several striking behavioral and physiological adaptations that allow this species to inhabit both the land and water environment. these features include unihemispheric slow wave sleep (usws, also being unihemispheric waking), the ability to maintain movement for stabilization of the sleep posture and to briefly open one eye while having a sleep electroencephalogram (eeg) in one hemisphere. in vivo microdialysis studies suggest tha ...201728505502
deciphering the evolutionary signatures of pinnipeds using novel genome sequences: the first genomes of phoca largha, callorhinus ursinus, and eumetopias jubatus.the pinnipeds, which comprise seals, sea lions, and walruses, are a remarkable group of marine animals with unique adaptations to semi-aquatic life. however, their genomes are poorly characterized. in this study, we sequenced and characterized the genomes of three pinnipeds (phoca largha, callorhinus ursinus, and eumetopias jubatus), focusing on site-wise sequence changes. we detected rapidly evolving genes in pinniped lineages and substitutions unique to pinnipeds associated with amphibious sou ...201830442995
hair mercury concentrations in the spotted seal (phoca largha) pups from the sea of japan.this publication presents the results of a study of the total mercury (thg) concentration in the fetal hair (lanugo) of the young spotted seals inhabiting the peter the great bay, sea of japan. we analyzed samples from pups that were collected in 2014-2017 at the seal breeding grounds. the concentration of total mercury was determined by atomic absorption spectrometry. the concentration of thg ranged from 1.52 to 6.68 μg/g dry weight. mercury concentration in the lanugo exceeds that found in the ...201830022391
brucella antibodies in alaskan true seals and eared seals-two different stories.brucella pinnipedialis was first isolated from true seals in 1994 and from eared seals in 2008. although few pathological findings have been associated with infection in true seals, reproductive pathology including abortions, and the isolation of the zoonotic strain type 27 have been documented in eared seals. in this study, a brucella enzyme-linked immunosorbent assay (elisa) and the rose bengal test (rbt) were initially compared for 206 serum samples and a discrepancy between the tests was fou ...201829445729
neuroethology: fur seals don't lose sleep over rem lost at sea.northern fur seals forego large amounts of rapid eye movement (rem) sleep when sleeping in water, but remain healthy and do not recover this loss once back on land, challenging current theories for the function of rem sleep.201829920262
fur seals suppress rem sleep for very long periods without subsequent rebound.virtually all land mammals and birds have two sleep states: slow-wave sleep (sws) and rapid eye movement (rem) sleep [1, 2]. after deprivation of rem sleep by repeated awakenings, mammals increase rem sleep time [3], supporting the idea that rem sleep is homeostatically regulated. some evidence suggests that periods of rem sleep deprivation for a week or more cause physiological dysfunction and eventual death [4, 5]. however, separating the effects of rem sleep loss from the stress of repeated a ...201829887309
digeneans of northern fur seals callorhinus ursinus (pinnipedia: otariidae) from five subpopulations on st. paul island, alaska.a parasitological survey of 651 northern fur seals callorhinus ursinus l. from five subpopulations was conducted on st. paul island, alaska, during july-august 2012-2014. digenean trematodes were found in 210 of 651 fur seals with a total prevalence of 32.3%. intensity of infection varied from 1 to 1540 parasites with mean intensity 18.4 ± 111.1 sd and median intensity of 2 specimens per host. significant differences in prevalence and intensity of infection in northern fur seals between separate ...201829435720
pairing ultrasonography with endocrinology to elucidate underlying mechanisms of successful pregnancy in the northern fur seal (callorhinus ursinus).reproductive success is one of the central tenets of conservation management programs, yet the inability to study underlying physiological processes in a minimally-invasive manner and the unpredictable nature of wild animal populations leaves large gaps in our knowledge of factors critical to successful reproduction in wild species. this study integrated ultrasonography of the reproductive tract and analysis of reproductive hormones in 172 northern fur seals (callorhinus ursinus) to identify int ...201829051074
evaluating exposure of northern fur seals, callorhinus ursinus, to microplastic pollution through fecal analysis.environmental microplastics are widely documented in marine life and bioaccumulation may present risks to marine predators. investigations of microplastics in marine mammals are increasing, though none have examined animals routinely consumed by humans. here, we investigate microplastic exposure in the northern fur seal (callorhinus ursinus), a species consumed by humans, using fecal material. we examined 44 feces (scat) at sites encompassing the seals' eastern pacific range. multiple contaminat ...201930660265
links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups.in marine mammals, muscular development has been identified as a rate-limiting factor in achieving adult dive capacities. this study investigates the rate that myosin heavy chain (mhc) composition matures in a postural and locomotor skeletal muscle for four pinniped species with different lactation lengths: hooded seals, cystophora cristata; harp seals, pagophilus groenlandicus; northern fur seals, callorhinus ursinus, and steller sea lions, eumetopias jubatus. the ontogeny of mhc isoform expres ...201931616978
factors affecting energy expenditure in a declining fur seal population.quantifying metabolic rates and the factors that influence them is key to wildlife conservation efforts because anthropogenic activities and habitat alteration can disrupt energy balance, which is critical for reproduction and survival. we investigated the effect of diving behaviour, diet and season on field metabolic rates (fmr) and foraging success of lactating northern fur seals (callorhinus ursinus) from the pribilof islands during a period of population decline. variation in at-sea fmr was ...201931890212
entanglement of northern fur seals (callorhinus ursinus) in marine debris on tyuleniy island (sea of okhotsk) in 1998-2013.the systematic annual observations of the northern fur seal rookery on tyuleniy (= robben) island, sea of okhotsk, were started in 1958. since 1975, all seals entangled in marine debris have been registered. some of the data on this issue, collected on the island in the late 20th century, were published earlier. this report provides data for the period of completion of the commercial sealing (from 1998 to 2013). during this period, a total of 867 fur seals were observed entangled in marine debri ...201931789154
migratory strategies of juvenile northern fur seals (callorhinus ursinus): bridging the gap between pups and adults.in species exhibiting differential migration by sex and age, understanding what differences exist, and the adaptive reasons for these differences is critical for determining how demographic groups will respond to environmental variability and anthropogenic perturbations. we used satellite-telemetered movement and diving data to investigate differential migration and its ontogeny in a highly migratory north pacific ocean predator, the northern fur seal (callorhinus ursinus; nfs), with a focus on ...201931558737
eye state asymmetry during aquatic unihemispheric slow wave sleep in northern fur seals (callorhinus ursinus).unihemispheric slow wave sleep (usws) is a unique form of sleep in which one brain hemisphere maintains low voltage electrical activity indicative of waking while the opposite exhibits slow wave electrical activity indicative of sleep. usws is present in several marine mammals and in some species of birds. one proposed biological function of usws is to enable the animal to monitor the environment to detect predators or conspecifics. while asymmetrical eye state was often observed during behavior ...201931116774
dental integration and modularity in pinnipeds.morphological integration and modularity are important for understanding phenotypic evolution because they constrain variation subjected to selection and enable independent evolution of functional and developmental units. we report dental integration and modularity in representative otariid (eumetopias jubatus, callorhinus ursinus) and phocid (phoca largha, histriophoca fasciata) species of pinnipedia. this is the first study of integration and modularity in a secondarily simplified dentition wi ...201930862801
review of metazoan parasites of the northern fur seal (callorhinus ursinus) and the analysis of the gastrointestinal helminth community of the population on st. paul island, alaska.the northern fur seal (nfs), callorhinus ursinus (mammalia: otariidae), is a marine mammal species included into the iucn red list as the vulnerable species which population is dramatically declining. a significant amount of parasitological data collected previously and our recent data allowed us to clarify the list of nfs metazoan parasites and to perform a comprehensive analysis of the gastrointestinal helminth community. gastrointestinal tracts from 756 nfss (3- to 4-year-old males) were coll ...202033159458
prevalence of serum antibodies to coxiella burnetii in alaska native persons from the pribilof islands.q fever is a febrile illness caused by infection with the bacterium coxiella burnetii. it is most often transmitted by inhalation of the bacteria after it is shed by infected livestock. recent studies have found very high c. burnetii infection rates among marine mammals, but it is not known if shedding by marine mammals creates a risk of q fever among humans. to better understand infection of humans with exposure to marine mammals, the prevalence of antibodies against c. burnetii in serum sample ...202031705592
stress-related and reproductive hormones in hair from three north pacific otariid species: steller sea lions, california sea lions and northern fur seals.assessing the physiological impact of stressors in pinnipeds is logistically challenging, and many hormones are altered by capture and handling, limiting the utility of metabolically active tissues. hair is increasingly being used to investigate stress-related and reproductive hormones in wildlife populations due to less-invasive collection methods, being metabolically inert once grown and containing multiple biomarkers of ecological interest. we validated enzyme immunoassays for measuring aldos ...202032843968
host population expansion and the genetic architecture of the pinniped hookworm uncinaria lucasi.the long-term fidelity of pinniped hosts to their natal rookery site suggests the genetic architecture of their uncinaria spp. hookworms should be strongly structured by host breeding biology. however, historical events affecting host populations may also shape parasite genetic structure. sequences of the mitochondrial cytochrome c oxidase 1 (coi) gene of 86 uncinaria lucasi individuals were obtained to assess genetic variation and structure of nematodes from 2 host species (68 hookworms from no ...202032491171
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