Pulmonary surfactant is a complex mixture of lipids and proteins that lowers surface tension, increases lung compliance, and prevents the adhesion of respiratory surfaces and pulmonary oedema. Pressure can have an enormous impact on respiratory function, by mechanically compressing tissues, increasing gas tension resulting in increased gas absorption and by increasing dissolved gas tensions during diving, resulting in the formation of bubbles in the blood and tissues. The lungs of diving mammals have a huge range of morphological adaptations to enable them to endure the extremely high pressures associated with deep diving. Here, I hypothesise that surfactant will also be modified, to complement the morphological changes and enable more efficient lung function during diving. Molecular adaptations to diving were examined in surfactant protein C (SP-C) using phylogenetic analyses. The composition and function of pulmonary surfactant from several species of diving mammals was examined using biochemical assays, mass spectrometry and captive bubble surfactometry. The development of surfactant in one species of diving mammal (California sea lion), and the control of surfactant secretion using chemical and mechanical stimuli were also determined. Diving mammals showed modifications to SP-C, which are likely to lead to stronger binding to the monolayer, thereby increasing its fluidity. Phospholipid molecular species concentrations were altered to increase the concentration of more fluid species. There was also an increase in the percentage of alkyl molecular species, which may increase the stability of the monolayer during compression and facilitate rapid respreading. Levels of SP-B were much lower in the diving species, and cholesterol was inversely proportional to the maximum dive depth of the three species. Surface activity of surfactant from diving mammals was very poor compared to surfactant from terrestrial mammals. The newborn California sea lion surfactant was similar to terrestrial mammal surfactant, suggesting that these animals develop the diving-type of surfactant after they first enter the water. The isolated cells of California sea lions also showed a similar response to neuro-hormonal stimulation as terrestrial mammals, but were insensitive to pressure. These findings showed diving mammal surfactant to have a primarily anti-adhesive function that develops after the first entry into the water, with a surfactant monolayer, which would be better suited to repeated collapse and respreading. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Pulmonary surfactant is a complex mixture of lipids and proteins that lowers surface tension, increases lung compliance, and prevents the adhesion of respiratory surfaces and pulmonary oedema. Pressure can have an enormous impact on respiratory function, by mechanically compressing tissues, increasing gas tension resulting in increased gas absorption and by increasing dissolved gas tensions during diving, resulting in the formation of bubbles in the blood and tissues. The lungs of diving mammals have a huge range of morphological adaptations to enable them to endure the extremely high pressures associated with deep diving. Here, I hypothesise that surfactant will also be modified, to complement the morphological changes and enable more efficient lung function during diving. Molecular adaptations to diving were examined in surfactant protein C (SP-C) using phylogenetic analyses. The composition and function of pulmonary surfactant from several species of diving mammals was examined using biochemical assays, mass spectrometry and captive bubble surfactometry. The development of surfactant in one species of diving mammal (California sea lion), and the control of surfactant secretion using chemical and mechanical stimuli were also determined. Diving mammals showed modifications to SP-C, which are likely to lead to stronger binding to the monolayer, thereby increasing its fluidity. Phospholipid molecular species concentrations were altered to increase the concentration of more fluid species. There was also an increase in the percentage of alkyl molecular species, which may increase the stability of the monolayer during compression and facilitate rapid respreading. Levels of SP-B were much lower in the diving species, and cholesterol was inversely proportional to the maximum dive depth of the three species. Surface activity of surfactant from diving mammals was very poor compared to surfactant from terrestrial mammals. The newborn California sea lion surfactant was similar to terrestrial mammal surfactant, suggesting that these animals develop the diving-type of surfactant after they first enter the water. The isolated cells of California sea lions also showed a similar response to neuro-hormonal stimulation as terrestrial mammals, but were insensitive to pressure. These findings showed diving mammal surfactant to have a primarily anti-adhesive function that develops after the first entry into the water, with a surfactant monolayer, which would be better suited to repeated collapse and respreading. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Thesis (Ph. D.)--University of Adelaide, 2005. / Title from PDF title page (viewed on Feb. 3, 2006). Includes bibliographical references.

As changing ocean conditions lead to declining fish stocks and movement of forage fish, sea lions on the Oregon coast are subject to the pressures of declining prey availability and increasing conflicts with commercial and recreational fisheries. An analysis of strandings of California sea lions, Zalophus californianus, and Steller sea lions, Eumetopias jubatus, from 2006 to 2014, included cause of death, changing ocean conditions, and anthropogenic activity. Causes of death included disease, injury, and human interaction, such as gunshot wounds, fisheries net entanglements and boat strikes. Oregon and Washington strandings of California sea lions are primarily adult and subadult males that migrate north from California rookeries, while Steller sea lions are year-round residents and strandings are comprised of males and females of all ages. While the California sea lion population is currently at or near carrying capacity, the Eastern Pacific population of Steller sea lions was designated as Threatened under the Endangered Species Act until October 2013. Understanding impacts to these two pinniped species is vital to implementing effective management and conservation policies. Oregon and southern Washington strandings of California sea lions and Steller sea lions from 2006 to 2014 were analyzed spatially using the geographic information system (GIS), and temporally to identify possible correlations with prey availability and human interaction. Strandings were found to follow seasonal patterns from year to year: Steller sea lion strandings were highest from May to July, California sea lions peaked in September, October, and November. There was a correlation between significantly high numbers of strandings and the three largest commercial fisheries in Oregon: Chinook salmon, Coho salmon, and Dungeness crab. This analysis provides a format for continuing to monitor primary ecological and anthropogenic drivers of pinniped mortality in Oregon and southern Washington.

Domoic acid (DA) is a neurotoxin produced by the harmful algae Pseudo-nitzschia that has been directly linked to mass stranding events of the California Sea Lion (CSL). The purpose of this paper is to review the anthropogenic influence on the production of this neurotoxin and examine how human activities are impacting this marine mammal species. A comprehensive and interdisciplinary literature review was conducted to evaluate the future sustainability of the CSL population. It was found that while Pseudo-nitzschia bloom developments are vulnerable to anthropogenic influences, the incontestable existence of natural contributing factors adds a certain complexity to the determination of causalities and the development of solutions. Strong evidence exists to show that DA can cause major and irreversible neurological damage in CSLs. Rehabilitation of DA-impacted CSLs is a polarizing issue in the U.S. and presents interesting implications for sustainable development. While the CSL population is currently healthy and plenteous, the strong abundance of future uncertainties warrants concern. A balance must be found between the involving social, economic, and environmental factors to ensure a promising future for the CSL species.

Introduction California sea lion (Zalophus californianus) health is severely compromised by domoic acid toxicosis, which occurs in high levels during harmful algal blooms of Pseudonitzschia australis along the coast of California. Current diagnostic protocols are often inconclusive due to a 2-48 hour window of detectability within the urinary, circulatory, and gastric systems (Cook, et al. 2011 and Monte, Pers Comm, 2012). Past studies suggest that Z. californianus, with domoic acid toxicosis, commonly display abnormal behaviors (Goldstein, et al. 2008). However, many of these abnormal behaviors are also associated with other diagnoses and are therefore unreliable as diagnostic indicators. This study fills in a knowledge gap relating to abnormal behavior types and their correlation to domoic acid toxicosis and helps solve the problem of current, inconclusive, diagnostic protocols. In this study, my objectives were to identify abnormal behaviors correlated to domoic acid toxicosis, create a diagnostic ethogram, determine the applicability of the method in the field, and determine the applicability of triage based on the relationship between abnormal behaviors and domoic acid levels. Methods I conducted focal animal continuous scans (continuous observation of a single animal at a time, for a set period) with continuous data entry, on animals admitted to the Marine Mammal Center (main study location during 2011-2013) and the Marine Mammal Care Center (comparison location, 2013). I conducted my observations from behind a blind to prevent both human habituation and behavioral influence of the observer. Observations lasted between 10-15 minutes (10 minutes per pen in 2011, 15 minutes per animal in 2012-2013). Subjects were selected based on an admit date no later than 7 days from the observation date. I conducted focal animal continuous scans at Pier 39, a haul out location, in the San Francisco Bay. Animals included in the study had identifying marks or were isolated from other animals (making them easy to identify). I observed animals once per observation day with a total observation period not exceeding 15 minutes per animal. I logged domoic acid levels in feces, urine, and serum (collected by veterinary staff and analyzed with liquid chromatography and bioassays for the presence of domoic acid). I then compared these results to the types and severity of abnormal behaviors displayed by the domoic acid toxicosis sample. Results Results from data collected at the Marine Mammal Center suggest that head weaving (Wilcoxon, p Results from the Pier 39 study suggest that behavioral criteria may be applicable for ruling out domoic acid toxicosis in groups of animals. However, I did not test the method during times of harmful algal blooms. Therefore, the applicability of the method for use as a diagnostic tool in the field is unknown and further research is required. Results for the triage study were inconclusive. The number of animals that tested positive for domoic acid was small and not suitable for statistical analysis. I suggest further research into triage abilities. Conclusion Based on the results of these studies, I can conclude that behavioral analysis offers a reliable diagnostic tool for rescued Z. californianus. Practitioners can use behavioral diagnostic criteria with confidence for the diagnosis of domoic acid toxicosis in Z. californianus.

An increase in marine mammal stranding and die-off events has been observed along the California coast. The exact cause to explain for these recent events is unknown, but El Niño and harmful algal blooms are established sources for temporary decreases in marine mammal health. To determine whether El Niño could be causing and amplifying harmful algal blooms, particularly in Monterey Bay where they occur frequently, data was analyzed from the Marine Mammal Center in Sausalito, California. Data analysis focused on California sea lions (Zalophus californianus), because they have the largest data set and are directly affected by harmful blooms from domoic acid. Results indicated that El Niño events could be significantly harming California sea lions in Monterey Bay during the fall season. Because agricultural runoff is a known factor in causing harmful algal blooms and Monterey Bay experiences them consistently, online research was conducted on agricultural activity, agricultural runoff and nitrogen contamination from fertilizer in the water-sheds surrounding Monterey Bay. Nitrogen contamination from agricultural use is a prominent issue, therefore, I proposed some possible solutions, including cap and trade, a water recycling plant, and eco-certification, to minimize nitrogen’s impact on the environment and wildlife while allowing farmers to continue using nitrogen on crops.

California sea lions (CSLs) have an unusually high occurrence of urogenital cancer (UGC), with studies revealing metastatic carcinoma in 26 % of CSLs admitted to a rehabilitation centre between 1998 and 2012. It is likely that the aetiology of this disease is multi-factorial as genetics, viral infection and exposure to contaminants have been associated with this cancer to date. The goal of this study was to investigate the association of a number of factors using a case-control study design on animals admitted to a rehabilitation centre. The study additionally concentrates on two main areas; (i) genetic factors and (ii) the presence of herpesvirus. Previous investigations identified cancer to be more likely in animals with specific microsatellite alleles. In the present study genotyping of CSLs at three microsatellite loci revealed that homozygosity at one marker (Pv11) was significantly associated with the presence of the disease. Pv11 was found to be located within a gene called heparanase 2 (HPSE2) and investigations into the expression of its protein revealed differences according to Pv11 genotype. The presence of herpesvirus was investigated by two PCR methods and identified the gammaherpesvirus OtHV-1. The results of the two methods were contradictory with one method identifying a highly significant relationship between the presence of OtHV-1 and UGC whereas the other did not. Complicating factors such as potential differences in sensitivity of the tests along with the possible presence of closely related viruses or variants of OtHV-1 may explain this. The availability of necropsy data for the CSLs in the study allowed the inclusion of body condition data in the statistical analysis to evaluate other potential risk factors. Final analysis revealed the presence of three risk factors; Pv11 genotype, OtHV-1 presence and thinner blubber. This study is the largest study undertaken so far in order to investigate the involvement of risk factors associated with UGC in the CSL and supports a multi-factorial aetiology of this disease.

Muscle samples from 105 marine mammals stranded along the Oregon-Washington coasts (2002-2009) were tested for levels of total mercury by Cold Vapor Atomic Fluorescence Spectrometry. The total mercury present is predominantly in the form of highly toxic methylmercury. After normalizing muscle tissue to 75% water weight, due to variance in water content, Steller sea lions (Eumetopias jubatus) and northern elephant seals (Mirounga angustirostris) exhibited the highest mean concentrations of total mercury followed by harbor seals (Phoca vitulina), harbor porpoises (Phocoena phocoena), and California sea lions (Zalophus californianus); 0.34 ± 0.278, 0.34 ± 0.485, 0.21 ± 0.216, 0.17 ± 0.169 and 0.15 ± 0.126 mg/kg normalized weight, respectively. Mean normalized values demonstrated limited muscle methylmercury accumulation in these species in the Pacific Northwest. Normalizing muscle mercury concentrations eliminated variability from desiccation, and allowed for a clearer indication of the amount of mercury the animal accumulated before stranding. However, actual wet weight concentrations in some of the stranded carcasses were high enough to pose a risk to scavengers.