Phylogeography of California and Galápagos sea lions and population structure within the California sea lion

2009 ◽  
Vol 156 (7) ◽  
pp. 1375-1387 ◽  
Author(s):  
Yolanda Schramm ◽  
S. L. Mesnick ◽  
J. de la Rosa ◽  
D. M. Palacios ◽  
M. S. Lowry ◽  
...  
Keyword(s):  
Population Structure ◽  
Sea Lion ◽  
California Sea Lion ◽  
Sea Lions

Quantifying errors associated with using fecal samples to determine the diet of the California sea lion (Zalophus californianus)

2001 ◽  
Vol 79 (6) ◽  
pp. 1080-1087 ◽  
Author(s):  
Anthony J Orr ◽  
James T Harvey
Keyword(s):  
Zalophus Californianus ◽  
Correction Factors ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Fecal Samples ◽  
Sea Lions ◽  
Mesh Bag ◽  
Estimate Number ◽  
Fish Otoliths

The purpose of this study was to quantify the errors associated with using fecal samples to determine the diet of the California sea lion (Zalophus californianus). Fishes and squids of known size and number were fed to five sea lions held in enclosures with seawater-filled pools. Enclosures were washed and pools were drained periodically so that sea lion feces could be collected using a 0.5 mm mesh bag. Fish otoliths and squid beaks were collected from feces and used to estimate number and size of prey eaten. An average of 50.7% (SE = 6.4%) of 430 fishes and 73.5% (SE = 12.0%) of 49 cephalopods fed to sea lions were represented by otoliths and beaks in feces, respectively. Estimated lengths of fish from feces were less than lengths of fish fed to sea lions by an average of 30.1% (SE = 2.8%). Beaks were not digested significantly; estimated lengths of squid were underestimated by an average of only 3.3% (SE = 1.5%) relative to actual lengths. Passage rates of otoliths varied, but more than 70% were recovered within 48 h after the fish was consumed. Passage rates of beaks were generally less than those of otoliths; six beaks (11%) were collected in feces 4 days after the squid were eaten. Correction factors were created to more reliably estimate the number and size of fishes and cephalopods eaten by California sea lions.

scholarly journals Transformation of the genital epithelial tract occurs early in California sea lion development

2016 ◽  
Vol 3 (3) ◽  
pp. 150419 ◽  
Author(s):  
Cecilia Barragán-Vargas ◽  
Jorge Montano-Frías ◽  
Germán Ávila Rosales ◽  
Carlos R. Godínez-Reyes ◽  
Karina Acevedo-Whitehouse
Keyword(s):  
Mhc Class Ii ◽  
Gulf Of California ◽  
Class Ii ◽  
Type I ◽  
Sea Lion ◽  
California Sea Lion ◽  
Viral Pathogen ◽  
Sea Lions ◽  
Adult Females ◽  
Urogenital Carcinoma

An unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging California sea lions stranded off the coast of California in the past two decades. No cases have been reported for sea lions in the relatively unpolluted Gulf of California. We investigated occurrence of genital epithelial transformation in 60 sea lions ( n =57 pups and 3 adult females) from the Gulf of California and examined whether infection by a viral pathogen previously found to be associated with urogenital carcinoma accounted for such alterations. We also explored the contribution of MHC class II gene expression on transformation. Cellular alterations, such as squamous cell atypia (ASC), atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions were observed in 42% of the pups and in 67% of the adult females. Normal genital epithelium was more common in male than female pups. ASC was five times more likely to occur in older pups. Epithelial alterations were unrelated to infection by the potentially oncogenic otarine type I gammaherpesvirus (OtHV-1), but ASCUS was more common in pups with marked and severe inflammation. Expression of MHC class II DRB loci ( Zaca DRB-D ) by peripheral antigen-presenting leucocytes showed a slightly ‘protective’ effect for ASC. We propose that transformation of the California sea lion genital epithelium is relatively common in young animals, increases with age and is probably the result of infection by an unidentified pathogen. Expression of a specific MHC class II gene, suggestive of presentation of specific antigenic peptides to immune effectors, appears to lower the risk of transformation. Our study provides the first evidence that epithelial transformation of the California sea lion genital tract is relatively common, even from an early age, and raises questions regarding differences in sea lion cancer-detection and -repair success between geographical regions.

Development, Comparison, and Validation Using ELISAs for the Determination of Domoic Acid in California Sea Lion Body Fluids

2014 ◽  
Vol 97 (2) ◽  
pp. 345-355 ◽  
Author(s):  
Erica L Seubert ◽  
Meredith D A Howard ◽  
Raphael M Kudela ◽  
Thomas N Stewart ◽  
R Wayne Litaker ◽  
...  
Keyword(s):  
Domoic Acid ◽  
Matrix Effects ◽  
Body Fluids ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Sea Lions ◽  
Technical Capability ◽  
Analytical Platforms

Abstract Mortalities of California sea lions (Zalophus californianus) attributed to the neurotoxin domoic acid (DA) produced by the diatom Pseudo-nitzschia have occurred repeatedly along the U.S. west coast since the late 1990s. Quantifying the amount of DA in these animals and correlating this information with the presence of DA in phytoplankton and the local food web has become a research focus for many scientists. However, differences in materials, equipment, technical capability, budgets, and objectives of the various groups and/or agencies involved in this work have influenced the DAquantification platforms used. The goal of the present study was to compare the performance of two commercially available ELISAs for the determination of DAin a spectrum of California sea lion body fluids andto compare the results with LC/MS of the same samples. The results indicated differences among these approaches, presumably owing to matrix effects (particularly urine) and antibody reactivities. This information implies that care should be taken in attemptingto compare datasets generated using different analytical platforms and interpreting the results of published studies.

scholarly journals Swimming in the California sea lion: morphometrics, drag and energetics

1987 ◽  
Vol 131 (1) ◽  
pp. 117-135 ◽  
Author(s):  
S. D. Feldkamp
Keyword(s):  
Drag Coefficient ◽  
Minimum Cost ◽  
Mechanical Efficiency ◽  
Energetic Cost ◽  
Sea Lion ◽  
California Sea Lion ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Aquatic Vertebrates ◽  
Wetted Surface Area

During swimming, the California sea lion, Zalophus californianus (Lesson), generates thrust forces solely by means of its pectoral flippers. This study examines the drag, energetic cost and efficiency associated with this method of locomotion. Sea lions are highly streamlined, with a fineness ratio of 5.5 and maximum girth at 40% of body length. This profile leads to reduced drag and swimming power requirements. Films of gliding animals showed the drag coefficient (based on wetted surface area) to be 0.0042 at a Reynolds number of 2.0 X 10(6). This value is comparable to that found for other aquatic vertebrates and suggests that the sea lion's morphology helps to delay turbulent separation and maintain laminar flow over the forward portion of its body. Swimming metabolism was measured in a water flume at velocities up to 1.3 ms-1. Effective swimming speeds up to 2.7 ms-1 were attained by increasing each animal's drag. Oxygen consumption rose exponentially with velocity and for two animals was best described as VO2 = 6.27e0.48U, where VO2 is in mlO2 min-1 kg-1 and U is in ms-1. Minimum cost of transport for these animals was 0.12 ml O2 kg-1 m-1 at a relative speed of 1.4 body lengths s-1. This is 2.5 times that predicted for a fish of similar size. Swimming efficiencies were determined from these results using power output values calculated from the measured drag coefficient and standard hydrodynamic equations. At the highest velocity, aerobic efficiency reached a maximum of 15% while mechanical efficiency of the foreflippers was 80%. The results demonstrate that foreflipper propulsion is a highly efficient and comparatively inexpensive method of locomotion in aquatic mammals.

Verminous Pneumonia in the California Sea Lion (Zalophus californianus)

1970 ◽  
Vol 7 (2) ◽  
pp. 89-101 ◽  
Author(s):  
Robert W. Fleischman ◽  
Robert A. Squire
Keyword(s):  
Bronchial Epithelium ◽  
Zalophus Californianus ◽  
Gastric Ulcers ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Sea Lions ◽  
Verminous Pneumonia ◽  
Liver Flukes ◽  
Underlying Pathogenesis

Verminous bronchitis and pneumonia due to Parafiaroides decorus infection is described in California sea lions ( Zalapbus californianus). Marked edema and multiple nodules occurred throughout the lungs. Histologically, both intact and degenerate lungworms occurred and the inflammatory response was pleomophic. A hyaline eosinophilic structure occurring beneath the tracheal and bronchial epithelium was morphologically similar to a structure seen in several human pulmonary diseases. Hypersensitivity may have been important in the underlying pathogenesis of This disease. Liver flukes ( Zalophotrema hepaaticum) and gastric ulcers containing nematodes ( Contraceacum osculalum) occurred in several animals.

scholarly journals Common cancer in a wild animal: the California sea lion ( Zalophus californianus ) as an emerging model for carcinogenesis

2015 ◽  
Vol 370 (1673) ◽  
pp. 20140228 ◽  
Author(s):  
Helen M. Browning ◽  
Frances M. D. Gulland ◽  
John A. Hammond ◽  
Kathleen M. Colegrove ◽  
Ailsa J. Hall
Keyword(s):  
Marine Mammals ◽  
Wild Animal ◽  
Zalophus Californianus ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Sea Lions ◽  
Terrestrial Mammals ◽  
The Usa ◽  
Urogenital Carcinoma

Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California sea lions ( Zalophus californianus ) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California sea lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews research to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California sea lion as an important and currently underexploited wild animal model of carcinogenesis.

scholarly journals New Records on Acanthocephalans from California Sea Lions Zalophus californianus (Pinnipedia, Otariidae) from California, USA

2018 ◽  
Vol 52 (3) ◽  
pp. 181-192 ◽  
Author(s):  
O. I. Lisitsyna ◽  
O. Kudlai ◽  
T. R. Spraker ◽  
T. A. Kuzmina
Keyword(s):  
New Records ◽  
Age Groups ◽  
Zalophus Californianus ◽  
Adult Males ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Sea Lions ◽  
Males And Females ◽  
First Time

Abstract To increase the currently limited knowledge addressing acanthocephalans parasitizing California sea lions (Zalophus californianus), 33 animals including pups, juvenile and adult males and females from the Marine Mammal Center (TMMC), Sausalito, California, USA were examined. Totally, 2,268 specimens of acanthocephalans representing five species from the genera Andracantha (A. phalacrocoracis and Andracantha sp.), Corynosoma (C. strumosum and C. obtuscens) and Profilicollis (P. altmani) were found. Profilicollis altmani and A. phalacrocoracis, predominantly parasitize fish-eating birds; they were registered in Z. californianus for the first time. Prevalence and intensity of California sea lion infection and transmission of acanthocephalans in these hosts of different age groups were analyzed and discussed. We provide brief morphological descriptions of the five species of acanthocephalan found in California sea lions.

Pupillometry in seals and sea lions: ecological implications

1997 ◽  
Vol 75 (12) ◽  
pp. 2050-2057 ◽  
Author(s):  
David Hendrik Levenson ◽  
Ronald J. Schusterman
Keyword(s):  
Sensory Modality ◽  
Maximum Size ◽  
Harbor Seal ◽  
Elephant Seal ◽  
Mirounga Angustirostris ◽  
Sea Lion ◽  
Northern Elephant Seal ◽  
California Sea Lion ◽  
Sea Lions ◽  
Light Levels

Phocid and otariid pinnipeds forage almost exclusively under water, where observing them is difficult. As a result, little is known of how their senses are used while diving to locate and capture prey. In this study we used pupillometric methods to describe the relative visual abilities of three pinniped species: the northern elephant seal (Mirounga angustirostris), the harbor seal (Phoca vitulina), and the California sea lion (Zalophus californianus). The range of pupillary area and lower limit of pupillary adjustment were determined for each species. The northern elephant seal exhibited the largest range of pupillary area of the species examined. Furthermore, the elephant seal's pupil was found to reach maximum size only under extremely dim conditions. Both the harbor seal and California sea lion exhibited maximum pupillary dilation in conditions several log units brighter. These results indicate that the elephant seal's visual system is designed to function in dimmer conditions and to respond to greater changes in light levels than those of the harbor seal and sea lion. Such findings support the hypothesis that the visual systems of these pinnipeds are adapted for use in their respective foraging environments, and thus suggest that the visual sense is probably an important sensory modality used to locate and capture prey while diving.

CYTOGENETIC COMPARISON OF SOME PINNIPEDS (MAMMALIA: EUTHERIA)

1967 ◽  
Vol 45 (5) ◽  
pp. 773-778 ◽  
Author(s):  
F. H. Fay ◽  
V. R. Rausch ◽  
E. T. Feltz
Keyword(s):  
Harbor Seal ◽  
Weddell Seal ◽  
Ringed Seal ◽  
Sea Lion ◽  
California Sea Lions ◽  
California Sea Lion ◽  
Weddell Seals ◽  
Sea Lions ◽  
Fur Seal ◽  
Pusa Hispida

Karyotypes of the harbor seal, Phoca vitulina (2N = 32), the bearded seal, Erignathus barbatus (2N = 34), the Weddell seal, Leptonychotes weddelli (2N = 34), the walrus, Odobenus rosmarus (2N = 32), the Steller sea lion, Eumetopias jubata (2N = 36), and the northern fur seal, Callorhinus ursinus (2N = 36), are described and compared with those of the ringed seal, Pusa hispida, and California sea lion, Zalophus californianus, reported by other workers. These are discussed with reference to current theories of pinniped phylogeny and systematics. The number and morphology of chromosomes in these eight species, representing each family and subfamily of pinnipeds, were found to be remarkably similar. This is interpreted as evidence of close interrelationship, commensurate with the theory of monophyletic origin. Karyograms of the harbor seal and ringed seal are virtually identical, as are those of the bearded and Weddell seals and those of the Steller and California sea lions. The karyotype of the fur seal is similar to the sea lions', while that of the walrus resembles the phocids' in some ways and the otariids' in others. A need for thorough comparative studies and reappraisal of pinniped systematics at the subfamilial and generic levels is indicated.

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