biological characterisation of sarcocystis neurona isolated from a southern sea otter (enhydra lutris nereis).sarcocystis neurona was isolated from the brain of a juvenile, male southern sea otter (enhydra lutris nereis) suffering from cns disease. schizonts and merozoites in tissue sections of the otter's brain reacted with anti-s. neurona antiserum immunohistochemically. development in cell culture was by endopolyogeny and mature schizonts were first observed at 3 days postinoculation. pcr of merozoite dna using primer pairs jnb33/jnb54 and restriction enzyme digestion of the 1100 bp product with dra ...200010779575
biological and molecular characterizations of toxoplasma gondii strains obtained from southern sea otters (enhydra lutris nereis).toxoplasma gondii was isolated from brain or heart tissue from 15 southern sea otters (enhydra lutris nereis) in cell cultures. these strains were used to infect mice that developed antibodies to t. gondii as detected in the modified direct agglutination test and had t. gondii tissue cysts in their brains at necropsy. mouse brains containing tissue cysts from 4 of the strains were fed to 4 cats. two of the cats excreted t. gondii oocysts in their feces that were infectious for mice. molecular an ...200010864250
evaluation of an indirect fluorescent antibody test (ifat) for demonstration of antibodies to toxoplasma gondii in the sea otter (enhydra lutris).an indirect fluorescent antibody test (ifat) for detection of toxoplasma gondii infection was validated using serum from 77 necropsied southern sea otters (enhydra lutris nereis) whose t. gondii infection status was determined through immunohistochemistry and parasite isolation in cell culture. twenty-eight otters (36%) were positive for t. gondii by immunohistochemistry or parasite isolation or both, whereas 49 (64%) were negative by both tests. at a cutoff of 1:320, combined values for ifat se ...200212099433
measurement of serum immunoglobulin concentration in killer whales and sea otters by radial immunodiffusion.killer whales and sea otters maintained in captivity are the subjects of routine health monitoring programs, and interest in immunologic studies in sea otters has been rising recently in response to potential impacts from infectious disease and environmental pollution on the threatened southern sea otter population. development of species-specific reagents for immunologic studies in these two marine mammals is currently in its infancy. in this study, killer whale and sea otter immunoglobulin-spe ...200212383650
characterization and clinical manifestations of arcanobacterium phocae infections in marine mammals stranded along the central california coast.between 1994 and 2000, 141 arcanobacterium phocae isolates were recovered from marine mammals that stranded along the central california coast (usa). arcanobacterium phocae was cultured from tissue sites with abnormal discharge or evidence of inflammation in 66 california sea lions (zalophus californianus), 50 pacific harbor seals (phoca vitulina richardii), 19 northern elephant seals (mirounga angustirostris), five southern sea otters (enhydra lutris nereis), and one common dolphin (delphinus d ...200312685077
molecular and antigenic characterization of bordetella bronchiseptica isolated from a wild southern sea otter (enhydra lutris nereis) with severe suppurative bronchopneumonia.bordetella bronchiseptica was isolated in pure culture from the lung, abdomen, and intestine of a wild free-ranging southern sea otter (enhydra lutris nereis) with severe, suppurative bronchopneumonia. immunohistochemistry, using antiserum raised to b. bronchiseptica, revealed strong positive staining of bacteria attached to bronchial ciliated epithelia as well as scattered positive staining in affected alveoli. western blot analysis demonstrated that virulence factors, filamentous hemagglutinin ...200314667021
clinical pathology and assessment of pathogen exposure in southern and alaskan sea otters.the southern sea otter (enhydra lutris nereis) population in california (usa) and the alaskan sea otter (e. lutris kenyoni) population in the aleutian islands (usa) chain have recently declined. in order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 ...200314733279
an unusual genotype of toxoplasma gondii is common in california sea otters (enhydra lutris nereis) and is a cause of mortality.toxoplasma gondii-associated meningoencephalitis is a significant disease of california sea otters (enhydra lutris nereis), responsible for 16% of total mortality in fresh, beachcast carcasses. toxoplasma gondii isolates were obtained from 35 california otters necropsied between 1998 and 2002. based on multi-locus pcr-restriction fragment length polymorphism and dna sequencing at conserved genes (18s rdna, its-1) and polymorphic genes (b1, sag1, sag3 and gra6), two distinct genotypes were identi ...200415003489
transplacental toxoplasmosis in a wild southern sea otter (enhydra lutris nereis).in september 2004, a neonatal sea otter pup was found alive on the beach in northern monterey bay, ca. efforts to locate the mother were unsuccessful. due to a poor prognosis for successful rehabilitation, the pup was euthanized. postmortem examination revealed emaciation, systemic lymphadenopathy and a malformation of the left cerebral temporal lobe. on histopathology, free tachyzoites and tissue cysts compatible with toxoplasma gondii were observed in the brain, heart, thymus, liver, lymph nod ...200818304737
canine distemper vaccination is a safe and useful preventive procedure for southern sea otters (enhydra lutra nereis).from 2002 to 2006, eight captive southern sea otters (enhydra lutris nereis) at research and display institutions in california at risk of exposure to potentially lethal morbiliviruses were vaccinated with a commercial recombinant poxvirus vectored canine distemper (cd) vaccine. serum-neutralizing (sn) antibody responses were followed for several years. the goal of this study was to determine whether 1) cd vaccination was a safe preventive medicine procedure for this species; 2) sea otters produ ...200920063817
oral papillomatosis caused by enhydra lutris papillomavirus 1 (elpv-1) in southern sea otters (enhydra lutris nereis) in california, usa.the southern sea otter (enhydra lutris nereis) is a threatened marine sentinel. during postmortem investigations of stranded sea otters from 2004 to 2013 in california, us, papillomas were detected in the oral cavity of at least seven otters via necropsy and histopathology. next-generation sequencing of viral particles purified from a single papilloma revealed a novel papillomavirus, enhydra lutris papillomavirus 1 (elpv-1). the genome of elpv-1 was obtained, representing the first fully sequenc ...201525647597
isolation and characterization of a novel marine brucella from a southern sea otter (enhydra lutris nereis), california, usa.we characterize brucella infection in a wild southern sea otter ( enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. this otter stranded twice along the central california coast, us over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. ultimately the otter was euthanized due to severe, progressive neurologic disease. necropsy and postmortem ...201728151078
bartonella spp. exposure in northern and southern sea otters in alaska and california.since 2002, an increased number of northern sea otters (enhydra lutris kenyoni) from southcentral alaska have been reported to be dying due to endocarditis and/or septicemia with infection by streptococcus infantarius subsp. coli. bartonella spp. dna was also detected in northern sea otters as part of mortality investigations during this unusual mortality event (ume) in kachemak bay, alaska. to evaluate the extent of exposure to bartonella spp. in sea otters, sera collected from necropsied and l ...201425514118
a protozoal-associated epizootic impacting marine wildlife: mass-mortality of southern sea otters (enhydra lutris nereis) due to sarcocystis neurona infection.during april 2004, 40 sick and dead southern sea otters (enhydra lutris nereis) were recovered over 18km of coastline near morro bay, california. this event represented the single largest monthly spike in mortality ever recorded during 30 years of southern sea otter stranding data collection. because of the point-source nature of the event and clinical signs consistent with severe, acute neurological disease, exposure to a chemical or marine toxin was initially considered. however, detailed post ...201020615616
endemic infection of stranded southern sea otters (enhydra lutris nereis) with novel parvovirus, polyomavirus, and adenovirus.over the past century, the southern sea otter (sso; enhydra lutris nereis) population has been slowly recovering from near extinction due to overharvest. the sso is a threatened species under federal law and a fully protected species under california law. through a multiagency collaborative program, stranded animals are rehabilitated and released, while deceased animals are necropsied and tissues are cryopreserved to facilitate scientific study. here, we processed archival tissues to enrich part ...201728192039
novel urease-negative helicobacter sp. 'h. enhydrae sp. nov.' isolated from inflamed gastric tissue of southern sea otters.a total of 31 sea otters enhydra lutris nereis found dead or moribund (and then euthanized) were necropsied in california, usa. stomach biopsies were collected and transected with equal portions frozen or placed in formalin and analyzed histologically and screened for helicobacter spp. in gastric tissue. helicobacter spp. were isolated from 9 sea otters (29%); 58% (18 of 31) animals were positive for helicobacter by pcr. the helicobacter sp. was catalase- and oxidase-positive and urease-negative ...201728177288
molecular characterization of sarcocystis neurona strains from opossums (didelphis virginiana) and intermediate hosts from central california.sarcocystis neurona is a significant cause of neurological disease in horses and other animals, including the threatened southern sea otter (enhydra lutris nereis). opossums (didelphis virginiana), the only known definitive hosts for s. neurona in north america, are an introduced species in california. s. neurona dna isolated from sporocysts and/or infected tissues of 10 opossums, 6 horses, 1 cat, 23 southern sea otters, and 1 harbor porpoise (phocoena phocoena) with natural infections was analy ...201020226596
limited genetic diversity among sarcocystis neurona strains infecting southern sea otters precludes distinction between marine and terrestrial isolates.sarcocystis neurona is an apicomplexan parasite identified as a cause of fatal neurological disease in the threatened southern sea otter (enhydra lutris nereis). in an effort to characterize virulent s. neurona strains circulating in the marine ecosystem, this study developed a range of markers relevant for molecular genotyping. highly conserved sequences within the 18s ribosomal gene array, the plastid-encoded rna polymerase (rpob) and the cytochrome c oxidase subunit 1 mitochondrial gene (co1) ...201020071081
enteric bacterial pathogen detection in southern sea otters (enhydra lutris nereis) is associated with coastal urbanization and freshwater runoff.although protected for nearly a century, california's sea otters have been slow to recover, in part due to exposure to fecally-associated protozoal pathogens like toxoplasma gondii and sarcocystis neurona. however, potential impacts from exposure to fecal bacteria have not been systematically explored. using selective media, we examined feces from live and dead sea otters from california for specific enteric bacterial pathogens (campylobacter, salmonella, clostridium perfringens, c. difficile an ...201019720009
prey choice and habitat use drive sea otter pathogen exposure in a resource-limited coastal system.the processes promoting disease in wild animal populations are highly complex, yet identifying these processes is critically important for conservation when disease is limiting a population. by combining field studies with epidemiologic tools, we evaluated the relationship between key factors impeding southern sea otter (enhydra lutris nereis) population growth: disease and resource limitation. this threatened population has struggled to recover despite protection, so we followed radio-tagged se ...200919164513
characterization of beta-hemolytic streptococci isolated from southern sea otters (enhydra lutris nereis) stranded along the california coast.the goal of this study was to characterize the beta-hemolytic streptococci cultured from southern sea otters (enhydra lutris nereis) stranded off the coast of california (usa) and to verify identifications made using the lancefield system. lancefield serotyping and biochemical analysis alone was inadequate for isolate characterization. final identification was based on sequence analysis of a portion of the 16s ribosomal rna gene from 12 of the 35 total isolates. the majority of isolates (10 of 1 ...200919117701
transmission of toxoplasma: clues from the study of sea otters as sentinels of toxoplasma gondii flow into the marine environment.toxoplasma gondii affects a wide variety of hosts including threatened southern sea otters (enhydra lutris nereis) which serve as sentinels for the detection of the parasite's transmission into marine ecosystems. toxoplasmosis is a major cause of mortality and contributor to the slow rate of population recovery for southern sea otters in california. an updated seroprevalence analysis showed that 52% of 305 freshly dead, beachcast sea otters and 38% of 257 live sea otters sampled along the califo ...200516157341
sporulation and survival of toxoplasma gondii oocysts in seawater.we have been collaborating since 1992 in studies on southern sea otters (enhydra lutris nereis) as part of a program to define factors, which may be responsible for limiting the growth of the southern sea otter population. we previously demonstrated toxoplasma gondii in sea otters. we postulated that cat feces containing oocysts could be entering the marine environment through storm run-off or through municipal sewage since cat feces are often disposed down toilets by cat owners. the present stu ...200314736220
patterns of mortality in southern sea otters (enhydra lutris nereis) from 1998-2001.detailed postmortem examination of southern sea otters (enhydra lutris nereis) found along the california (usa) coast has provided an exceptional opportunity to understand factors influencing survival in this threatened marine mammal species. in order to evaluate recent trends in causes of mortality, the demographic and geographic distribution of causes of death in freshly deceased beachcast sea otters necropsied from 1998-2001 were evaluated. protozoal encephalitis, acanthocephalan-related dise ...200314567210
molecular and bioassay-based detection of toxoplasma gondii oocyst uptake by mussels (mytilus galloprovincialis).toxoplasma gondii is associated with morbidity and mortality in a variety of marine mammals, including fatal meningoencephalitis in the southern sea otter (enhydra lutris nereis). the source(s) of t. gondii infection and routes of transmission in the marine environment are unknown. we hypothesise that filter-feeding marine bivalve shellfish serve as paratenic hosts by assimilation and concentration of infective t. gondii oocysts and their subsequent predation by southern sea otters is a source o ...200313129531
helminth parasites of the southern sea otter enhydra lutris nereis in central california: abundance, distribution and pathology.from october 1997 to may 2001, the gastrointestinal tracts from 162 beach-cast southern sea otters enhydra lutris nereis were examined for helminth parasites and associated lesions. carcasses were collected opportunistically in central california between pt. san pedro and pt. arguello. the primary goals of this study were to examine spatial and temporal variability in mortality due to parasite infection, identify factors associated with increased risk of infection, and illustrate the process of ...200312608572
coastal freshwater runoff is a risk factor for toxoplasma gondii infection of southern sea otters (enhydra lutris nereis).the association among anthropogenic environmental disturbance, pathogen pollution and the emergence of infectious diseases in wildlife has been postulated, but not always well supported by epidemiologic data. specific evidence of coastal contamination of the marine ecosystem with the zoonotic protozoan parasite, toxoplasma gondii, and extensive infection of southern sea otters (enhydra lutris nereis) along the california coast was documented by this study. to investigate the extent of exposure a ...200212076629
molecular cloning and sequencing of interleukin 6 cdna fragments from the harbor seal (phoca vitulina), killer whale (orcinus orca), and southern sea otter (enhydra lutris nereis).using polymerase chain reaction, interleukin-6 (il-6) cdna fragments from harbor seal (phoca vitulina), killer whale (orcinus orca), and southern sea otter (enhydra lutris nereis) were cloned and sequenced. for all three species, a continuous open reading frame encoding 203 residues for harbor seal, 199 residues for killer whale, and 201 residues for sea otter with stop codons located at analogous positions were identified. these fragments correspond to nucleotides 71 - 753 of the human il-6 tra ...19968575817
a new pathogen transmission mechanism in the ocean: the case of sea otter exposure to the land-parasite toxoplasma gondii.toxoplasma gondii is a land-derived parasite that infects humans and marine mammals. infections are a significant cause of mortality for endangered southern sea otters (enhydra lutris nereis), but the transmission mechanism is poorly understood. otter exposure to t. gondii has been linked to the consumption of marine turban snails in kelp (macrocystis pyrifera) forests. it is unknown how turban snails acquire oocysts, as snails scrape food particles attached to surfaces, whereas t. gondii oocyst ...201324386100
epidemiology and pathology of toxoplasma gondii in free-ranging california sea lions (zalophus californianus).the coccidian parasite toxoplasma gondii infects humans and warm-blooded animals worldwide. the ecology of this parasite in marine systems is poorly understood, although many marine mammals are infected and susceptible to clinical toxoplasmosis. we summarized the lesions associated with t. gondii infection in the california sea lion (zalophus californianus) population and investigated the prevalence of and risk factors associated with t. gondii exposure, as indicated by antibody. five confirmed ...201525588007
sea otter health: challenging a pet hypothesis.a recent series of studies on tagged sea otters (enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to toxoplasma gondii in central california. counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of di ...201526155464
coccidioidomycosis and other systemic mycoses of marine mammals stranding along the central california, usa coast: 1998-2012.a wide range of systemic mycoses have been reported from captive and wild marine mammals from north america. examples include regionally endemic pathogens such as coccidioides and blastomyces spp., and novel pathogens like cryptococcus gattii, which appear may have been introduced to north america by humans. stranding and necropsy data were analyzed from three marine mammal stranding and response facilities on the central california coast to assess the prevalence, host demographics, and lesion d ...201525647598
evaluation of cardiac lesions and risk factors associated with myocarditis and dilated cardiomyopathy in southern sea otters (enhydra lutris nereis).to describe cardiac lesions and identify risk factors associated with myocarditis and dilated cardiomyopathy (dcm) in beach-cast southern sea otters.200515757130
ultrastructural and molecular confirmation of the development of sarcocystis neurona tissue cysts in the central nervous system of southern sea otters (enhydra lutris nereis).in 2004, three wild sea otters were diagnosed with putative sarcocystis neurona-associated meningoencephalitis by histopathology and immunohistochemistry. schizonts, free merozoites and tissue cysts were observed in the brains of all three infected animals. tissue cysts walls from sea otter 1 (so1) stained positively using anti-s. neurona polyclonal antiserum. however, positive staining does not preclude infection by closely related or cross-reactive tissue cyst-forming coccidian parasites. two ...200919527725
estimating cause-specific mortality rates using recovered carcasses.stranding networks, in which carcasses are recovered and sent to diagnostic laboratories for necropsy and determination of cause of death, have been developed to monitor the health of marine mammal and bird populations. these programs typically accumulate comprehensive, long-term datasets on causes of death that can be used to identify important sources of mortality or changes in mortality patterns that lead to management actions. however, the utility of these data in determining cause-specific ...200919204341
temporal association between land-based runoff events and california sea otter (enhydra lutris nereis) protozoal mortalities.toxoplasma gondii and sarcocystis neurona have caused significant morbidity and mortality in threatened southern sea otters (enhydra lutris nereis) along the central california coast. because only terrestrial animals are known to serve as definitive hosts for t. gondii and s. neurona, infections in otters suggest a land to sea flow of these protozoan pathogens. to better characterize the role of overland runoff in delivery of terrestrially derived fecal pathogens to the near shore, we assessed t ...201222493114
dual congenital transmission of toxoplasma gondii and sarcocystis neurona in a late-term aborted pup from a chronically infected southern sea otter (enhydra lutris nereis).toxoplasma gondii and sarcocystis neurona are protozoan parasites with terrestrial definitive hosts, and both pathogens can cause fatal disease in a wide range of marine animals. close monitoring of threatened southern sea otters (enhydra lutris nereis) in california allowed for the diagnosis of dual transplacental transmission of t. gondii and s. neurona in a wild female otter that was chronically infected with both parasites. congenital infection resulted in late-term abortion due to dissemina ...201626494610
california mussels (mytilus californianus) as sentinels for marine contamination with sarcocystis neurona.sarcocystis neurona is a terrestrial parasite that can cause fatal encephalitis in the endangered southern sea otter (enhydra lutris nereis). to date, neither risk factors associated with marine contamination nor the route of s. neurona infection to marine mammals has been described. this study evaluated coastal s. neurona contamination using california mussels (mytilus californianus) as sentinels for pathogen pollution. a field investigation was designed to test the hypotheses that (1) mussels ...201627003262
epidemiology and potential land-sea transfer of enteric bacteria from terrestrial to marine species in the monterey bay region of california.marine mammals are at risk for infection by fecal-associated zoonotic pathogens when they swim and feed in polluted nearshore marine waters. because of their tendency to consume 25-30% of their body weight per day in coastal filter-feeding invertebrates, southern sea otters (enhydra lutris nereis) can act as sentinels of marine ecosystem health in california. feces from domestic and wildlife species were tested to determine prevalence, potential virulence, and diversity of selected opportunistic ...201222740531
the flehmen response and pseudosuckling in a captive, juvenile southern sea otter (enhydra lutris nereis).a juvenile, female sea otter (enhydra lutris nereis) was observed in 43 instances of the flehmen response over 19 days from may through july of 2015 at the oregon zoo. in all flehmen grimace observations, the juvenile sea otter engaged in nibbling, nosing, or licking the peri-mammary or anogenital areas of a non-lactating, geriatric female sea otter. the flehmen behavior observed was consisted with the sequences of behavior documented in other mammals, lifting the head, elevating the nose to the ...201728111787
ontogenetic scaling of theoretical bite force in southern sea otters (enhydra lutris nereis).sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. although recent studies have indicated that southern sea otters (enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be inve ...201627617357
comparison of human and southern sea otter (enhydra lutris nereis) health risks for infection with protozoa in nearshore waters.cryptosporidium and giardia spp. are waterborne, fecally-transmitted pathogens that cause economic loss due to gastroenteritis and beach closures. we applied quantitative microbial risk assessment (qmra) to determine the health risks for humans and sea otters due to waterborne exposure of cryptosporidium and giardia spp. when swimming in three types of surface waters: river, stormwater and wastewater effluent during the wet and dry seasons in the central coast of california. this is the first ap ...201627525585
evaluating potential conservation conflicts between two listed species: sea otters and black abalone.population consequences of endangered species interacting as predators and prey have been considered theoretically and legally, but rarely investigated in the field. we examined relationships between spatially variable populations of a predator, the california sea otter, enhydra lutris nereis, and a prey species, the black abalone, haliotis cracherodii. both species are federally listed under the endangered species act and co-occur along the coast of california. we compared the local abundance a ...201527070027
the high cost of motherhood: end-lactation syndrome in southern sea otters (enhydra lutris nereis) on the central california coast, usa.sea otters ( enhydra lutris ) have exceptionally high energetic requirements, which nearly double during lactation and pup care. thus, females are extremely vulnerable to caloric insufficiency. despite a number of compensatory strategies, the metabolic challenge of reproduction culminates in numerous maternal deaths annually. massive depletion of energy reserves results in a case presentation that we define as end-lactation syndrome (els), characterized by moderate to severe emaciation not attri ...201626967137
characterization of the temporomandibular joint of southern sea otters (enhydra lutris nereis).the structure-function relationship of the temporomandibular joint (tmj) of southern sea otter has largely not been described. this study aims to describe the histological, biochemical, and biomechanical features of the tmj disk in the southern sea otter. the tmj disks from fresh cadaver heads of southern sea otter adult males (n = 8) and females (n = 8) acquired from strandings were examined. following macroscopical evaluation, the tmjs were investigated for their histological, mechanical, and ...201526664997
ontogeny of oxygen storage capacity and diving ability in the southern sea otter (enhydra lutris nereis): costs and benefits of large lungs.small body size, large lungs, and dense pelage contribute to the unique challenges faced by diving sea otters (enhydra lutris) when compared to other marine mammals. here we determine the consequences of large lungs on the development of diving ability in southern sea otters (enhydra lutris nereis) by examining the ontogeny of blood, muscle, and lung oxygen stores and calculating aerobic dive limits (cadl) for immature and mature age classes. total oxygen storage capacity matures rapidly in sea ...201525860829
the cost of reproduction: differential resource specialization in female and male california sea otters.intraspecific variation in behavior and diet can have important consequences for population and ecosystem dynamics. here, we examine how differences in reproductive investment and spatial ecology influence individual diet specialization in male and female southern sea otters (enhydra lutris nereis). we hypothesize that greater reproductive constraints and smaller home ranges of females lead to more pronounced intraspecific competition and increased specialization. we integrate stable carbon (δ(1 ...201525669450
timescales alter the inferred strength and temporal consistency of intraspecific diet specialization.many populations consist of individuals that differ substantially in their diets. quantification of the magnitude and temporal consistency of such intraspecific diet variation is needed to understand its importance, but the extent to which different approaches for doing so reflect instantaneous vs. time-aggregated measures of individual diets may bias inferences. we used direct observations of sea otter individuals (enhydra lutris nereis) to assess how: (1) the timescale of sampling, (2) under-s ...201525656583
energetic demands of immature sea otters from birth to weaning: implications for maternal costs, reproductive behavior and population-level trends.sea otters (enhydra lutris) have the highest mass-specific metabolic rate of any marine mammal, which is superimposed on the inherently high costs of reproduction and lactation in adult females. these combined energetic demands have been implicated in the poor body condition and increased mortality of female sea otters nearing the end of lactation along the central california coast. however, the cost of lactation is unknown and currently cannot be directly measured for this marine species in the ...201424920834
novel poxvirus infection in northern and southern sea otters (enhydra lutris kenyoni and enhydra lutris neiris), alaska and california, usa.small superficially ulcerated skin lesions were observed between october 2009 and september 2011 during captive care of two orphaned sea otter pups: one northern (enhydra lutris kenyoni) in alaska and one southern (enhydra lutris nereis) in california. inclusions consistent with poxviral infection were diagnosed by histopathology in both cases. virions consistent with poxvirus virions were seen on electron microscopy in the northern sea otter, and the virus was successfully propagated in cell cu ...201424807180
the dental pathology of southern sea otters (enhydra lutris nereis).skulls (n = 1,205) of southern sea otters were examined macroscopically according to defined criteria. the museum specimens, acquired from strandings, varied in age from juvenile to adult, with an equal sex distribution. the results from all young adult and adult specimens were pooled according to tooth type. ninety-two percent of teeth were available for examination, with 6.5% artifactually absent, 0.6% deemed absent due to acquired tooth loss and 0.03% deemed congenitally absent. all teeth wer ...201323348015
osteosarcoma of the maxilla with concurrent osteoma in a southern sea otter (enhydra lutris nereis).southern sea otters (enhydra lutris nereis) are threatened marine mammals that belong to the family mustelidae and are native to the coast of central california. neoplasia is reported infrequently in sea otters. an adult female free-ranging southern sea otter was found alive at pebble beach, monterey county, california, on january 1st, 1994 and died soon after capture. the carcass was submitted to the us geological survey - national wildlife health center for necropsy examination. grossly, a mas ...201622520807
sound production and reception in southern sea otters (enhydra lutris nereis).because of their dependence on a highly restricted coastal habitat, enhydra lutris is especially vulnerable to a variety of different environmental and anthropogenic threats. this species is presently listed as threatened and is protected throughout the northern and southern portions of its range.resource managers are presently faced with uncertainty when responding to and prioritizing potential threats to these animals due to insufficient understanding of the factors that may disturb or disrupt ...201222278472
vitamin a deficiency and hepatic retinol levels in sea otters, enhydra lutris.vitamin a deficiency has rarely been reported in captive or free-ranging wildlife species. necropsy findings in two captively housed southern sea otters (enhydra lutris nereis) included irregular thickening of the calvaria characterized by diffuse hyperostoses on the internal surface. one animal also had moderate squamous metaplasia of the seromucinous glands of the nose. there was no measurable retinol in the liver of either sea otter. for comparison, hepatic retinol concentration was determine ...201122946376
a reanalysis of competing hypotheses for the spread of the california sea otter.from 1938 to 1972, the range of california sea otters (enhydra lutris nereis) expanded with the northern and southern fronts spreading at rates of approximately 1.4 km/yr and 3.1 km/yr, respectively. j. a. lubina and s. a. levin proposed the following three factors to explain the large disparity in spread rates: (1) regional differences in dispersal; (2) regional differences in population growth; and (3) advection due to the known presence of a southerly flowing offshore current. while lubina an ...200919769128
using stable isotopes to investigate individual diet specialization in california sea otters (enhydra lutris nereis).differences in diet composition among conspecifics (dietary specialization) have been documented across a broad range of taxonomic groups and habitats, and such variation at the individual level is increasingly recognized as an important component of diversity in trophic interactions. accurate identification of individual dietary specialization, however, requires longitudinal dietary records that are labor-intensive and cost-prohibitive to obtain for many species. here we explore the use of stab ...200919449691
using demography and movement behavior to predict range expansion of the southern sea addition to forecasting population growth, basic demographic data combined with movement data provide a means for predicting rates of range expansion. quantitative models of range expansion have rarely been applied to large vertebrates, although such tools could be useful for restoration and management of many threatened but recovering populations. using the southern sea otter (enhydra lutris nereis) as a case study, we utilized integro-difference equations in combination with a stage-structu ...200818839772
a comparative analysis of polybrominated diphenyl ethers and polychlorinated biphenyls in southern sea otters that died of infectious diseases and noninfectious causes.southern sea otters (enhydra lutris nereis) from the california coast continue to exhibit a slower population regrowth rate than the population in alaska. infectious diseases have been identified as a frequent cause of death. infectious diseases caused by varied pathogens including bacteria, fungi, and parasites were suggestive of compromised immunological health of mature animals in this population. to test the hypothesis that elevated exposure to immunotoxic contaminants such as polybrominated ...200717587145
incorporating diverse data and realistic complexity into demographic estimation procedures for sea otters.reliable information on historical and current population dynamics is central to understanding patterns of growth and decline in animal populations. we developed a maximum likelihood-based analysis to estimate spatial and temporal trends in age/sex-specific survival rates for the threatened southern sea otter (enhydra lutris nereis), using annual population censuses and the age structure of salvaged carcass collections. we evaluated a wide range of possible spatial and temporal effects and used ...200617205905
the development of methods for immunophenotypic and lymphocyte function analyzes for assessment of southern sea otter (enhydra lutris nereis) health.the southern sea otter (enhydra lutris nereis) is listed as threatened under the endangered species act. the population began a pattern of slow decline in 1995. the decline was attributed to high adult mortality rates with infectious disease being the major cause of death. multiple pathogens were implicated in these deaths including opportunistic pathogens such as coccidiodes immitis and toxoplasma sp. these findings suggested that the immunological health of mature animals in this population mi ...200515661326
isolation and characterization of sarcocystis from brain tissue of a free-living southern sea otter (enhydra lutris nereis) with fatal meningoencephalitis.a protozoan was isolated in cell culture from the brain of a free-ranging sea otter with fatal meningoencephalitis. the biological history of this otter, a study animal being monitored via an intraperitoneal radio transmitter, is summarized. histologically, protozoal parasites were associated with areas of brain inflammation and necrosis in the cerebrum and cerebellum. morphology and measurements of fixed, giemsa-stained protozoal zoites growing on coverslips were consistent with sarcocystis. th ...200111293576
relationships among sarcocystis species transmitted by new world opossums (didelphis spp.).at least three species of sarcocystis (s. neurona, s. falcatula, s. speeri) have recently been shown to use opossums of the genus didelphis as their definitive host. in order to evaluate the evolutionary relationships among sarcocystis spp. isolates from the americas, and to determine whether organisms representing the same parasite lineages are transmitted north and south of the panamanian isthmus, we inferred the phylogenetic relationships from nucleotide sequence variation in parasites isolat ...200111223194
foraging strategies and prey switching in the california sea otter.southern sea otters (enhydra lutris nereis), in recovering from near extinction, are gradually extending their range to include areas from which they have been absent for more than one hundred years. this study took advantage of the otters' relatively sudden arrival in the area near santa cruz, california, to monitor their prey selection in the first two years of residence there. foraging observations revealed that sea urchins (strongly-locentrotus franciscanus) were heavily preyed upon initiall ...198228311106
first report of an adult tapeworm (cestoda: diphyllobothriidea) in a southern sea otter (enhydra lutris nereis).we present a novel case of an intestinal cestode infection in a southern sea otter (enhydra lutris nereis). the cestode species diplogonoporus tetrapterus was confirmed genetically. stable isotope analysis of whiskers collected from the sea otter did not confirm the consumption of fish as the route of exposure.201728640666
serologic detection of subtype-specific antibodies to influenza a viruses in southern sea otters (enhydra lutris nereis).there are approximately 3,000 southern sea otters (enhydra lutris nereis) in the nearshore environment along the california coast, and the species is classified as threatened under the endangered species act. we tested sera from 661 necropsied southern sea otters sampled from 1997 to 2015 to determine overall exposure to influenza a viruses (iavs) and to identify subtype-specific antibody responses. using an enzyme-linked immunosorbent assay (elisa), antibodies to iav nucleoproteins were detecte ...201728513329
modified-closed castration: a novel technique for sea otter (enhydra lutris nereis) orchiectomies.a novel surgical technique was used in the routine castrations of two intact male southern sea otters, enhydra lutris nereis, housed at the georgia aquarium (atlanta, georgia, usa). this technique involved incising the parietal vaginal tunic to allow placement of double ligation of the ductus deferens, testicular artery, and pampiniform plexus en masse. after ligating and transecting these structures, they were introduced back into the tunic, which was closed with a circumferential ligature. the ...201324063115
osteoarthritis of the temporomandibular joint in southern sea otters (enhydra lutris nereis).museum skull specimens (n = 1,008) of southern sea otters (enhydra lutris nereis) were examined macroscopically according to defined criteria for the presence, severity and characteristics of temporomandibular joint osteoarthritis (tmj-oa). the specimens were from stranded young adult to adult animals. overall, 4.1% of the specimens had findings consistent with tmj-oa. of these, 61.0% were from females and 39.0% were from males. in addition, 85.4% of the affected specimens were from adults and 1 ...201323721871
prevalence, pathology, and risk factors associated with streptococcus phocae infection in southern sea otters (enhydra lutris nereis), 2004-10.recent studies have implicated beta-hemolytic streptococci as opportunistic pathogens of marine mammals, including southern sea otters (enhydra lutris nereis), but little is known about their prevalence or pathophysiology. herein, we focus on risk factors for sea otter infection by a single beta-hemolytic streptococcal species, streptococcus phocae. streptococcus phocae was first identified as a marine mammal pathogen in 1994, and the first report in southern sea otters was in 2009. its broad ho ...201626555115
novel bartonella infection in northern and southern sea otters (enhydra lutris kenyoni and enhydra lutris nereis).since 2002, vegetative valvular endocarditis (vve), septicemia and meningoencephalitis have contributed to an unusual mortality event (ume) of northern sea otters in southcentral alaska. streptococcal organisms were commonly isolated from vegetative lesions and organs from these sea otters. bartonella infection has also been associated with bacteremia and vve in terrestrial mammals, but little is known regarding its pathogenic significance in marine mammals. our study evaluated whether streptoco ...201424629902
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