California Sea Lions Zalophus Californianus Research Articles

Hookworms (Uncinaria lyonsi) in Dead California Sea Lion (Zalophus californianus) Pups and Sand in Winter (2014–2015) on San Miguel Island, California

ABSTRACT: Necropsy of dead California sea lion (CSL) (Zalophus californianus) pups (n = 20) born in 2014 was done on San Miguel Island, California, in December 2014 and February 2015. The main objective was to obtain data on prevalence/intensity of hookworms (Uncinaria lyonsi) in pups at that time of the year and to compare the results with data from previous studies conducted in December, January, and February. Fourteen dead pups were examined for adult hookworms in December 2014; all pups were infected (prevalence = 100%) with intensity from 6 to 140 (average 58.9 ± 38.9 SD) nematodes per host. Six dead pups were examined in February 2015. Hookworms were present in the intestines of 2 pups (prevalence=33%); two adult female worms were found in each infected pup. From 1 to 23 (average 7.5) parasitic larvae (L3) were found in the blubber of 4 pups. The findings in this study (2014–2015) verify, from earlier observation, that adult U. lyonsi are shed by pups by late February. The prevalence of parasitic L...

PHARMACOKINETICS OF TRAMADOL HYDROCHLORIDE AND ITS METABOLITE O-DESMETHYLTRAMADOL FOLLOWING A SINGLE, ORALLY ADMINISTERED DOSE IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

Tramadol is a synthetic, centrally acting, opiate-like analgesic that is structurally related to codeine and morphine. The objective of this study was to determine the pharmacokinetics of tramadol hydrochloride and its major active metabolite O-desmethyltramadol (M1) in the California sea lion (Zalophus californianus). A single dose of tramadol was administered orally in fish at 2 mg/kg to a total of 15 wild California sea lions admitted for rehabilitation. Twenty-four total blood samples were collected post drug administration at 10, 20, 30, and 45 min and at 1, 3, 5, 6, 8, 12, and 24 hr. Blood plasma was separated and stored at -80°C until analysis with high-performance liquid chromatography was performed to determine levels of tramadol and M1, the major active metabolite. The results indicate that the plasma levels of parent tramadol are low or negligible during the first 30-45 min and then reach the predicted mean maximum plasma concentration of 358 ng/ml at 1.52 hr. The M1 metabolite was not detectable in 21 of 24 plasma samples, below the level of quantification of 5 ng/ml in one sample, and detectable at 11 and 17 ng/ml in two of the samples. This study suggests that a 2 mg/kg dose would need to be administered every 6-8 hr to maintain concentrations of tramadol above the minimum human analgesic level for mild to moderate pain. Based on dosing simulations, a dose of 4 mg/kg q8 hr or q12 hr, on average, may represent an adequate compromise, but further studies are needed using a larger sample size. Pharmacodynamic studies are warranted to determine if tramadol provides analgesic effects in this species. The potential for tramadol toxicosis at any dose also has not been determined in this species.

PHARMACOKINETICS OF SINGLE-DOSE ORALLY ADMINISTERED CIPROFLOXACIN IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

Ciprofloxacin is commonly selected for clinical use due to its broad-spectrum efficacy and is a frequently administered antibiotic at The Marine Mammal Center, a marine mammal rehabilitation facility. Ciprofloxacin is used for treatment of California sea lions ( Zalophus californianus ) suffering from a variety of bacterial infections at doses extrapolated from other mammalian species. However, as oral absorption is variable both within and across species, a more accurate determination of appropriate dosage is needed to ensure effective treatment and avoid emergence of drug-resistant bacterial strains. A pharmacokinetic study was performed to assess plasma concentrations of ciprofloxacin in California sea lions after a single oral dose. Twenty healthy California sea lions received a single 10-mg/kg oral dose of ciprofloxacin administered in a herring fish. Blood was then collected at two of the following times from each individual: 0.5, 0.75, 1, 2, 4, 8, 10, 12, 18, and 24 hr postingestion. Plasma ciprofloxacin concentration was assessed via high-performance liquid chromatography. A population pharmacokinetics model demonstrated that an oral ciprofloxacin dose of 10 mg/kg achieved an area under the concentration vs. time curve of 6.01 μg hr/ml. Absorption was rapid, with ciprofloxacin detectable in plasma 0.54 hr after drug administration; absorption half-life was 0.09 hr. A maximum plasma concentration of 1.21 μg/ml was observed at 1.01 hr, with an elimination half-life of 3.09 hr. Ciprofloxacin administered orally at 10 mg/kg produced therapeutic antibacterial exposure for only some of the most susceptible bacterial organisms commonly isolated from California sea lions.

Insights into the life history and ecology of a large shortfin mako shark Isurus oxyrinchus captured in southern California.

In June 2013, a record-breaking female Isurus oxyrinchus (total length 373 cm, mass 600 kg) was captured by rod and reel off Huntington Beach, California, where it was subsequently donated to research and provided a rare opportunity to collect the first data for a female I. oxyrinchus of this size. Counts of vertebral band pairs estimate the shark to have been c. 22 years old, depending upon assumptions of band-pair deposition rates, and the distended uteri and spent ovaries indicated that this shark had recently given birth. The stomach contained a c. 4 year-old female California sea lion Zalophus californianus that confirmed the high trophic position of this large I. oxyrinchus, which was corroborated with the high levels of measured contaminants and tissue isotope analyses.

FOCAL BACTERIAL MENINGITIS FOLLOWING ASCENDING BITE WOUND INFECTION LEADING TO PARAPARESIS IN A CAPTIVE CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS)

Magnetic resonance imaging was performed on a 15-yr-old captive female California sea lion (Zalophus californianus) with a 2-wk history of progressive paraparesis and a 9-mo history of exudative skin lesion on the left thoracic wall. Magnetic resonance images showed a well-defined muscle infiltrating lesion ventrolateral to the seventh cervical to the third thoracic vertebra on the left side, which extended through the left intervertebral foramina C7 to T3 into the vertebral canal, causing spinal cord compression and displacement as well as inflammation of the spinal cord and nerves. This lesion surprisingly caused no forelimb deficits. Differential diagnoses included abscess formation or neoplasia. Pathologic examination revealed chronic focal purulent meningitis associated with widespread paraspinal fistulous inflammation originating from a chronic dermal ulcer. Mainly Escherichia coli var. haemolytica and Clostridium perfringens were identified as the underlying agents.

Description of Uncinaria lyonsi n. sp. (Nematoda: Ancylostomatidae) from the California sea lion Zalophus californianus Lesson (Carnivora: Otariidae).

A new species of hookworm, Uncinaria lyonsi n. sp., is described based on morphological studies of the nematodes collected by Dr. E. T. Lyons from the California sea lion Zalophus californianus (Lesson) on San Miguel Island, California, USA. The new species is morphologically similar to three other species of the genus Uncinaria Frölich, 1789 parasitising pinnipeds, U. lucasi Stiles, 1901, U. hamiltoni Baylis, 1933 and U. sanguinis Marcus, Higgins, Šlapeta & Gray, 2014, in the body dimensions, the structure of the buccal capsule, the shape and structure of the male caudal bursa and female genital system. Uncinaria lyonsi n. sp. is differentiated from U. lucasi by having longer spicules and gubernaculum, larger buccal capsule and more slender oesophagus. The new species differs from U. hamiltoni and U. sanguinis in having shorter spicules and narrower buccal capsule. The latter two species also occur in the Southern Hemisphere and are geographically separated from U. lyonsi n. sp. The present study confirms the existence of a host-specific species of Uncinaria in the California sea lion, previously revealed by molecular and biological investigations.

Can Sea Lions’ (Zalophus californianus) Use Mirrors to Locatean Object?

Although California sea lions (Zalophus californianus) are capable of forming complex mental concepts, they have failed to demonstrate mirror self-recognition, a skill that requires both a mental representation of one’s physical features and knowledge of a reflective surface. Many non-human species that do not recognize themselves in mirrors can nonetheless learn to use mirror reflections to locate and retrieve objects. A total of 7 sea lions housed at 2 separate facilities were tested on their ability to detect an object using a mirror. The results of a preliminary detection task in which sea lions were reinforced for looking at a mirror to locate an object suggested that 4 sea lions reliably learned to locate an object positioned below a mirror in one of three locations. A follow-up study was conducted to determine if 3 different sea lions could learn the task without training the animals to use the mirrors. Two of the 3 sea lions located a single object in 1 of the 3 locations statistically above chance when the mirrors were added to the task for the first time. With additional mirror exposure, 1 sea lion successfully achieved 100% accuracy in detecting familiar objects placed in 1 of 3 familiar locations. This sea lion also demonstrated her ability to detect an object via a mirror located in a novel, fourth position with 100% accuracy. When two novel objects were tested with four locations, the sea lion again performed well, detecting the objects 87.5%. The results suggest that sea lions have the ability to use mirrors to locate an object with minimal exposure to a mirror, but likely need additional experience with mirrors to efficiently use the properties of these reflective surfaces and understand that the image is a two-dimensional representation of a three-dimensional object.

Short Note: Unprecedented Resighting in Mexico of a Male California Sea Lion (Zalophus californianus) from Oregon During the 2014 Breeding Season

Short Note: Unprecedented Resighting in Mexico of a Male California Sea Lion (Zalophus californianus) from Oregon During the 2014 Breeding Season

Development of a real-time PCR for the detection of pathogenic Leptospira spp. in California sea lions.

Several real-time PCR assays are currently used for detection of pathogenic Leptospira spp.; however, few methods have been described for the successful evaluation of clinical urine samples. This study reports a rapid assay for the detection of pathogenic Leptospira spp. in California sea lions Zalophus californianus using real-time PCR with primers and a probe targeting the lipL32 gene. The PCR assay had high analytic sensitivity-the limit of detection was 3 genome copies per PCR volume using L. interrogans serovar Pomona DNA and 100% analytic specificity; it detected all pathogenic leptospiral serovars tested and none of the non-pathogenic Leptospira species (L. biflexa and L. meyeri serovar Semaranga), the intermediate species L. inadai, or the non-Leptospira pathogens tested. Our assay had an amplification efficiency of 1.00. Comparisons between the real-time PCR assay and culture isolation for detection of pathogenic Leptospira spp. in urine and kidney tissue samples from California sea lions showed that samples were more often positive by real-time PCR than by culture methods. Inclusion of an internal amplification control in the real-time PCR assay showed no inhibitory effects in PCR negative samples. These studies indicated that our real-time PCR assay has high analytic sensitivity and specificity for the rapid detection of pathogenic Leptospira species in urine and kidney tissue samples.

Two‐sex matrix models in assessing population viability: when do male dynamics matter?

SummaryWhile most demographic population models used in conservation rely on female vital rates, recent empirical evidence suggests that male dynamics should be included in population models used for assessing extinction risk.UsingCalifornia sea lionsZalophus californianusas an applied example, we demonstrate that there are situations in which two‐sex models are more appropriate than the commonly used female‐based model.Two‐sex models are relevant in cases where vital rates for sexes differ and for polygamous species such as sea lions. Vital rates targeted for management may therefore respond differently for males and females and for different assumptions about sex ratio.Synthesis and applications. Conservation biologists should carefully consider the social structure and sex ratio of focal species in order to determine whether a two‐sex matrix model will yield more accurate estimates of extinction risk than standard one‐sex models.

OCCURRENCE OFPASTEURELLACEAEBACTERIA IN THE ORAL CAVITY OF SELECTED MARINE MAMMAL SPECIES

The occurrence of bacteria belonging to Pasteurellaceae in the oral cavity of captive marine mammals was investigated using culture and subsequent geno- and phenotypic characterization and phylogenetic analyses. A total of 89 bacterial isolates from pinnipeds tentatively classified with the family Pasteurellaceae were further characterized by phylogenetic analysis of rpoB gene sequences, which showed that the isolates investigated formed five distinct groups. Four strains from California sea lions (Zalophus californianus) made up group I, which was classified with Pasteurella canis. Group II comprised four strains from harbor seals (Phoca vitulina) and grey seals (Halichoerus grypus) classified with Pasteurella stomatis. Group III consisted of 28 strains, isolated from harbor and gray seals and represented Bisgaardia genomospecies 1. Two strains from a harbor and a grey seal, group IV, were classified with Bisgaardia hudsonensis. Fifty-two strains from northern fur seals (Callorhinus ursinus), walruses (Odobenus rosmarus), and California and Steller sea lions (Eumetopias jubatus) formed group V and represented Otariodibacter oris. No Pasteurellaceae isolates were obtained from cetaceans, but Pasteurellaceae were isolated from all sampled pinnipeds. On the basis of these results, it is very likely that Pasteurellaceae bacteria represent a part of the normal oral flora in pinnipeds.

Clinical relevance of novel Otarine herpesvirus-3 in California sea lions (Zalophus californianus): lymphoma, esophageal ulcers, and strandings

Herpesviruses have been recognized in marine mammals, but their clinical relevance is not always easy to assess. A novel otarine herpesvirus-3 (OtHV3) was detected in a geriatric California sea lion (Zalophus californianus), and using a newly developed quantitative PCR assay paired with histology, OtHV3 was associated with esophageal ulcers and B cell lymphoblastic lymphoma in this animal. The prevalence and quantities of OtHV3 were then determined among buffy coats from 87 stranded and managed collection sea lions. Stranded sea lions had a higher prevalence of OtHV3 compared to managed collection sea lions (34.9% versus 12.5%; p = 0.04), and among the stranded sea lions, yearlings were most likely to be positive. Future epidemiological studies comparing the presence and viral loads of OtHV3 among a larger population of California sea lions with and without lymphoid neoplasia or esophageal ulcers would help elucidate the relevance of OtHV3-associated pathologies to these groups.

Skin histology and its role in heat dissipation in three pinniped species.

BackgroundPinnipeds have a thick blubber layer and may have difficulty maintaining their body temperature during hot weather when on land. The skin is the main thermoregulatory conduit which emits excessive body heat.MethodsThorough evaluation of the skin histology in three pinniped species; the California sea lion-Zalophus californianus, the Pacific harbor seal-Phoca vitulina richardsi, and the Northern elephant seal-Mirounga angustirostris, was conducted to identify the presence, location and distribution of skin structures which contribute to thermoregulation. These structures included hair, adipose tissue, sweat glands, vasculature, and arteriovenous anastomoses (AVA). Thermal imaging was performed on live animals of the same species to correlate histological findings with thermal emission of the skin.ResultsThe presence and distribution of skin structures directly relates to emissivity of the skin in all three species. Emissivity of skin in phocids (Pacific harbor and Northern elephant seals) follows a different pattern than skin in otariids (California sea lions). The flipper skin in phocids tends to be the most emissive region during hot weather and least emissive during cold weather. On the contrary in otariids, skin of the entire body has a tendency to be emissive during both hot and cold weather.ConclusionHeat dissipation of the skin directly relates to the presence and distribution of skin structures in all three species. Different skin thermal dissipation patterns were observed in phocid versus otariid seals. Observed thermal patterns can be used for proper understanding of optimum thermal needs of seals housed in research facilities, rescue centers and zoo exhibits.

Use of Radiotelemetry and Direct Observations to Evaluate Sea Lion Predation on Adult Pacific Salmonids at Bonneville Dam

AbstractManagement of protected species becomes increasingly complex when one protected population negatively affects another. This occurs along coastlines and in rivers and estuaries of the U.S. Pacific Northwest, where protected marine mammals prey on threatened and endangered Pacific salmonids Oncorhynchus spp. Over 9 years, we observed a growing aggregation of California sea lions Zalophus californianus and Steller sea lions Eumetopias jubatus preying upon adult Chinook salmon O. tshawytscha and steelhead O. mykiss at Bonneville Dam on the Columbia River. Both before and concurrent with the observation study, we monitored radio‐tagged salmon at Bonneville Dam and during their upriver spawning migrations. Springtime sea lion abundance steadily increased from 2002 to 2010 and the aggregation formed earlier each winter. The principal prey species in winter were resident white sturgeon Acipenser transmontanus and migratory steelhead and then shifted to predominantly Chinook salmon when the spring run arrived. Observation‐based estimates of salmonid consumption from January to May varied 12‐fold among years (0.4–4.9%, mean = 2.6% of adult salmonids counted at the dam), and radiotelemetry results corroborated these estimates. The highest proportional impact was in winter and early spring. As salmonid abundance increased, per capita consumption by sea lions increased (Type II functional response) but individual salmonid risk decreased (due to prey swamping). Population‐specific risk analyses indicated predation was substantially higher for early‐timed than for late‐timed salmon populations. The most at‐risk group included Snake River and upper Columbia River Chinook salmon listed as threatened under the U.S. Endangered Species Act. These predation indices should help managers simultaneously tasked with salmon recovery and marine mammal management.

THORACIC AUSCULTATION IN CAPTIVE BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS), CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS), AND SOUTH AFRICAN FUR SEALS (ARCTOCEPHALUS PUSILLUS) WITH AN ELECTRONIC STETHOSCOPE

Thoracic auscultation is an important diagnostic method used in cases of suspected pulmonary disease in many species, as respiratory sounds contain significant information on the physiology and pathology of the lungs and upper airways. Respiratory diseases are frequent in marine mammals and are often listed as one of their main causes of death. The aim of this study was to investigate and report baseline parameters for the electronic-mediated thoracic auscultation of one cetacean species and two pinniped species in captivity. Respiratory sounds from 20 captive bottlenose dolphins (Tursiops truncatus), 6 California sea lions (Zalophus californianus), and 5 South African fur seals (Arctocephalus pusillus) were recorded with an electronic stethoscope. The sounds were analyzed for duration of the respiratory cycle, adventitious sounds, and peak frequencies of recorded sounds during expiration and inspiration as well as for sound intensity as reflected by waveform amplitude during the respiratory cycle. In respiratory cycles of the bottlenose dolphins' expiring "on command," the duration of the expiration was significantly shorter than the duration of the inspiration. In the examined pinnipeds of this study, there was no clear pattern concerning the duration of one breathing phase: Adventitious sounds were detected most often in bottlenose dolphins that were expiring on command and could be compared with "forced expiratory wheezes" in humans. This is the first report of forced expiratory wheezes in bottlenose dolphins; they can easily be misinterpreted as pathologic respiratory sounds. The peak frequencies of the respiratory sounds reached over 2,000 Hz in bottlenose dolphins and over 1,000 Hz in California sea lions and South African fur seals, but the variation of the frequency spectra was very high in all animals. To the authors' knowledge, this is the first systematic analysis of respiratory sounds of bottlenose dolphins and two species of pinnipeds.

Multicentric Neurofibromatosis With Rectal Prolapse in a California Sea Lion (Zalophus californianus)

An approximately 31-yr-old California sea lion (Zalophus californianus) with a history of chronic visual impairment and corneal disease presented with slow onset, progressive neurologic deficits. Treatment for rear flipper paresis was not effective and the animal was euthanatized. Histopathologic findings included hepatocellular and biliary neoplasia, ocular amyloidosis, adrenal adenoma and pheochromocytoma, and spinal cord changes consistent with multicentric neurofibromatosis. This is the first documentation of these conditions in a California sea lion.

Evidence of injury caused by gas bubbles in a live marine mammal: barotrauma in a California sea lion Zalophus californianus

A yearling male California sea lion Zalophus californianus with hypermetric ataxia and bilateral negative menace reflexes was brought to The Marine Mammal Center, Sausalito, California, U.S.A., in late 2009 for medical assessment and treatment. The clinical signs were due to multiple gas bubbles within the cerebellum. These lesions were intraparenchymal, multifocal to coalescing, spherical to ovoid, and varied from 0.5 to 2.4 cm diameter. The gas composed 21.3% of the total cerebellum volume. Three rib fractures were also noted during diagnostic evaluation and were presumed to be associated with the gas bubbles in the brain. The progression of clinical signs and lesion appearance were monitored with magnetic resonance imaging, cognitive function testing and computed tomography. Gas filled voids in the cerebellum were filled with fluid on follow up images. Clinical signs resolved and the sea lion was released with a satellite tag attached. Post release the animal travelled approximately 75 km north and 80 km south of the release site and the tag recorded dives of over 150 m depth. The animal re-stranded 25 d following release and died of a subacute bronchopneumonia and pleuritis. This is the first instance of clinical injury due to gas bubble formation described in a living pinniped and the first sea lion with quantifiable cerebellar damage to take part in spatial learning and memory testing.

Isolation of a novel adenovirus from California sea lions Zalophus californianus

Viral hepatitis associated with adenoviral infection has been reported in California sea lions Zalophus californianus admitted to rehabilitation centers along the California coast since the 1970s. Canine adenovirus 1 (CAdV-1) causes viral hepatitis in dogs and infects a number of wildlife species. Attempts to isolate the virus from previous sea lion hepatitis cases were unsuccessful, but as the hepatitis had morphologic features resembling canine infectious hepatitis, and since the virus has a wide host range, it was thought that perhaps the etiologic agent was CAdV-1. Here, we identify a novel adenovirus in 2 stranded California sea lions and associate the infection with viral hepatitis and endothelial cell infection. Phylogenetic analysis confirmed the classification of the sea lion adenovirus in the Mastadenovirus genus with the most similarity to tree shrew adenovirus 1 (TSAdV-1, 77%). However, as the sea lion adenovirus appeared to be equally distant from the other Mastadenovirus species based on phylogenetic analysis, results indicate that it represents an independent lineage and species. Although sequences from this novel virus, otarine adenovirus 1 (OtAdV-1), show some similarity to CAdV-1 and 2, it is clearly distinct and likely the cause of the viral hepatitis in the stranded California sea lions.

Antemortem diagnosis of a ventricular septal defect in a California sea lion Zalophus californianus

A yearling California sea lion Zalophus californianus stranded in poor body condition, and on physical examination a heart murmur was audible bilaterally. The sea lion was diagnosed with a left-to-right shunting membranous ventricular septal defect (VSD) using B-mode, color-flow Doppler and continuous-wave Doppler echocardiography. A left-to-right intracardiac shunting lesion was confirmed during cardiac angiographic computed tomography. The VSD defect was verified during the necropsy examination. On histologic examination concurrent mild multifocal myocarditis with focal mild ventricular free-wall myocardial necrosis were identified. A specific cause for the myocarditis and myocardial necrosis was not found, and association with the VSD and resultant myocardial dysfunction was presumed. This is the first report of the antemortem diagnosis of a VSD in a marine mammal and the first report of a VSD in a California sea lion.

Complexity of domoic acid-related sea lion strandings in Monterey Bay, California: foraging patterns, climate events, and toxic blooms

The neurotoxin domoic acid (DA) produced by the diatoms Pseudo-nitzschia has been responsible for deaths of marine mammals and birds in Monterey Bay, California, USA. In this study we examined links between DA-related strandings of the seasonally migratory California sea lion Zalophus californianus and regional occurrences of DA-producing diatoms using a decade-long time series. Results suggest a more complex pattern of stranding than anticipated, one not related simply to regional abundance of the toxin producers. Stranding patterns of sea lions exhibiting signs of acute DA toxicosis may be best explained by multiple causative factors including timing of toxic blooms with respect to the sea lion breeding cycle, adequacy of sea lion prey during the breeding season, as well as the geographic range of this pinniped outside of the breeding season. Three DA-related stranding events occurred in Monterey Bay in 1998, 2000 and 2007, when toxic DA blooms were pre- sent in the Bay and the California coast was experiencing El Nino/Southern Oscillation conditions. Foraging centers near the breeding site likely provided inadequate food for individuals, leading to northerly movement of these highly mobile predators to other geographic sites resulting in exposure to toxic DA-producing blooms. High toxic Pseudo-nitzschia and DA concentrations did not, however, result in DA-related stranding events in 2002, 2003 and 2004, when weaker than normal upwelling events were present in the Bay. Relative productivity of central versus southern California with respect to the breeding season thus appears to strongly influence the frequency of DA-related strand- ings in Monterey Bay, California.