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    Klebsiella pneumoniae in New Zealand sea lions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2018) Pinpimai, Komkiew
    Klebsiella pneumoniae has been circulating in New Zealand sea lions since the outbreaks during the breeding seasons of 2001/02 and 2002/03 in Sandy Bay, on Enderby Island, Auckland Islands. A large number of pups have since died from K. pneumoniae every year during the breeding season. In order to prevent and control this infection, baseline data including bacterial phenotype and genotype, geographic distribution of the pathogen, and the immune response to the pathogen, have to be established. In this study, hypervirulent (HV) K. pneumoniae was isolated from different sources including New Zealand sea lion (NZSL) pups from different breeding sites, and characterised using a combination of biochemical, phenotypic tests, serological analysis and genotyping via whole genome sequencing. Isolates from pups, substrate samples from different breeding sites, a NZSL adult and birds, all had a close genetic relationship. The isolates have the same basic characteristics including a hypermucoviscous phenotype, serotype 2, and sequence type 86. This suggested clonality of this pathogen. The geographic distribution of the pathogen was found to be Enderby Island, Dundas Island, Campbell Island, and the Otago Peninsula (New Zealand mainland). The isolates analysed were all susceptible to commonly used antibiotics, with the exception of ampicillin. The HV isolates from pups were able to utilise a wide panel of carbon and nitrogen sources and had activity in a wide range of pH from 4.5 to 10, supporting the ability of this pathogen to survive in diverse environments. The findings in this thesis also suggest that the environment can be a reservoir for a short time period. For the long term, between breeding seasons, New Zealand sea lion adults and birds that live around the breeding site are potential reservoirs. The HV isolates from pups were resistant to some innate immune responses, including serum killing ability, oxidative killing ability and phagocytosis by neutrophils and monocytes. Overall, this study provided phenotypic and genotypic information on K. pneumoniae isolated from NZSL pups, as well as some information about innate immune responses to this pathogen, which can aid in the prevention and control of this infection.
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    An investigation of vitamin D metabolism in kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus) and New Zealand sea lion (Phocarctos hookeri) and the relationship of vitamin D metabolism with their life history characteristics : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies at Massey University, Turitea, Palmerston North, New Zealand
    (Massey University, 2016) Kale, Madhumita Sanjay
    Vitamin D, a fat-soluble vitamin, has a wide range of functions in vertebrates. The aim of the study was to determine if the evolutionary history of different animal species affects their predominant route of vitamin D metabolism. The species chosen in this study were Brown kiwi (Apteryx mantelli) for their nocturnalism, tuatara (Sphenodon punctatus) for their diurnal sun basking nature and New Zealand sea lion (Phocarctos hookeri), as a marine mammal species. A survey of plasma or serum concentrations of 25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3) in kiwi, tuatara and New Zealand sea lion and analysed the ability of skin to produce vitamin D3 in response to UV exposure from post mortem samples of these three species. Assessment of morepork (Ninox novaseelandiae) skin was also carried out as an additional example of a nocturnal species. Wild kiwi had lower plasma 25(OH)D3 concentrations than captive kiwi and this variation was most likely of dietary origin. The low concentrations of plasma 25(OH)D3 in wild kiwi in their natural habitat, suggest that these minimal levels are sufficient to fulfill their vitamin D requirements in the body or they utilise calcium independent of vitamin D. Captive diets for kiwi may be over-supplemented with vitamin D. In contrast to this finding, the skin of both kiwi and morepork was able to produce small but measureable amounts of vitamin D3 in response to UV exposure. This result was unexpected, considering their nocturnal nature and the overall pattern of vitamin D metabolism in the kiwi is still unclear. Vitamin D metabolism in tuatara suggests that both dietary and dermal pathways are important. The survey of plasma 25(OH)D3 concentrations in captive tuatara showed variation between the five zoological institutions, which was correlated to the variation in the dietary vitamin D provided between captive institutions. However, analysis of tuatara skin showed that tuatara had a strong ability to synthesise vitamin D dermally, indicating that it is an important route of vitamin D metabolism in tuatara. New Zealand sea lion showed overall higher serum 25(OH)D3 concentrations than kiwi and tuatara, which might be attributed to the high UV-B radiation exposure they receive in their natural habitat. New Zealand sea lion skin also had comparatively higher vitamin D concentrations both prior to and in response to UV exposure, which shows that dermal route of vitamin D is an important route of metabolism in these marine mammals.
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    Causes of mortality and characterisation of Mycobacteriosis in adult New Zealand sea lions (Phocarctos Hookeri) at Enderby Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science in Wildlife Health at Massey University, Manawatū, Palmerston North, New Zealand
    (Massey University, 2017) Lenting, Baukje Mirjam
    The New Zealand sea lion (Phocarctos hookeri) is classified as endangered and “Nationally Critical” due to a declining population and restricted population range. There have been recent bacterial epizootic events at the breeding colonies of this species, however the role of disease in the population decline is not known. As part of the investigation into the population decline, the species management plan recommends investigation of disease agents affecting this species, their epidemiology and their long-term effects on population dynamics. Since the 1998/1999 breeding season, post mortem examinations have been performed on deceased New Zealand sea lions at the Enderby Island breeding colonies during each breeding season, including the collection of samples for histology and bacteriology. This study describes the causes of mortality in New Zealand sea lions one year of age and older at Enderby Island between the 1998/99 to 2010/11 breeding seasons inclusive, using the archived post mortem reports, histology samples and bacteriology samples. Conspecific trauma was found to be a significant cause of mortality (34.3%), as were various infectious causes (35.7%). The organism Klebsiella pneumoniae was isolated from non-pup New Zealand sea lions both from individuals that died from other causes and individuals that showed apparent morbidity as a result of this bacteria. These findings suggest that older animals may be reservoirs of infection for K. pneumoniae, which causes significant mortality in neonatal New Zealand sea lions. Another important infectious agent that was described in non-pup New Zealand sea lions was Mycobacterium pinnipedii, which caused both subclinical and clinical disease. Mycobacteriosis of the lymph nodes, lungs, pleura, liver, peritoneum and reproductive tract was described in this study. Strain determination of the M. pinnipedii isolates grown show only minor strain variation among isolates, which may reflect the isolated geographic distribution of these animals. There was no apparent association between the individual strains of M. pinnipedii and their pathogenicity as indicated by the pathology present in infected animals.
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    Assessing the impacts of infectious disease on reproductive success in New Zealand sea lions (Phocarctos hookeri) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science in Wildlife Health at Massey University, Palmerston North, Manawatū, New Zealand
    (Massey University, 2014) Michael, Sarah Anne
    Poor reproductive success is one factor that may be perpetuating the population decline of the threatened New Zealand (NZ) sea lion (Phocarctos hookeri). The species has a severely restricted distribution, with 99% of breeding occurring on the remote NZ sub-Antarctic islands and amongst the lowest expected reproductive outputs compared to other otariids. Infectious disease, particularly septicaemia caused by the bacterium Klebsiella pneumoniae is known to be a major mediator of early pup mortality, but the role of infectious disease in impairment of reproductive success has not been investigated. This thesis aimed to fill this knowledge gap by investigating three areas of concern. Firstly, the role of infectious disease in stillbirth of NZ sea lion pups was examined with a histopathological study of archived necropsy tissues. Secondly, the seroprevalence of adult and juvenile NZ sea lions to Toxoplasma gondii, a known cause of reproductive failure, at several locations was evaluated. Finally, a survival analysis was conducted to model the long term survival and reproductive success of pups that were treated with ivermectin as pups, to assess ongoing benefits of early hookworm burden removal. In contrast to the mass mortalities seen with bacterial disease in NZ sea lion colonies, at least in the topics covered in this thesis, the role of infectious disease contributing to poor reproductive success is apparently minimal. No specific infectious agents were identified to have caused the death of the stillborn pups examined, however pneumonia was diagnosed in four animals. A low seroprevalence to T. gondii was found in mainland but not sub-Antarctic colonies, however those animals with strongly positive titres showed no clinical signs and had reproduced normally. Finally, although the survival analysis was limited by small sample size and very poor juvenile survival, it depicted promising trends for improved survival for those pups treated with ivermectin as pups. All studies have generated areas for future research and recommendations for further conservation management of this vulnerable species.
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    The role of long-term diet change in the decline of the New Zealand sea lion population : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Manawatū, New Zealand
    (Massey University, 2013) Stewart-Sinclair, Phoebe
    The New Zealand sea lion (Phocarctos hookeri) is an endangered pinniped endemic to New Zealand (Wilkinson, Burges et al. 2003). Declared “nationally critical” under the NZ threat classification system and “vulnerable in decline” by IUCN, they have shown a 49% decline in pup production since 1995 (Chilvers, Wilkinson et al. 2010). I investigated the role of long-term changes in diet on the population ecology of NZ sea lions. I was interested in the role played by long-term changes in diet into the observed decline of the sea lion population. My study is set apart from others in that it spans 13 years of routine sampling, and represents one of the longest timelines of diet data for any pinniped species. I used scat and regurgitate samples from New Zealand sea lions that were collected at the Auckland Islands between the summer of 1995/1996 and 2012/2013. I identified 11 main prey types from hard parts including otoliths, beaks and other diagnostic bones. In scats these main prey types were opalfish (Hemerocoetes spp.), rattail (Macrouridae), red cod (Pseudophycis bachus), octopus (Octopus sp.) and arrow squid (Ommastrephidae), Ling (Genypterus blacodes), smallscaled cod (Paranotothenia sp.), hoki (Macruronus novaezelandiae), triplefin (Tripterygiidae), fur seal (Arctocephalus forsteri) and giant octopus (Enteroctopus zealandicus). Main prey types found in regurgitates were similar but there was a higher proportion of cephalopods than in scat samples. When assessing long-term trends in occurrence of main prey species I found that smaller prey types such as opalfish and Octopus sp. have been increasing in the diet over time, while larger species hoki and giant octopus have been decreasing. The ratio of fish:cephalopods in NZ sea lion diet has also been decreasing with time, possibly indicating an overall reduction in diet quality. I used catch per unit effort as a proxy for prey availability in the environment and compared this to frequency of occurrence (%FO) of main prey types over time. The best models for functional response by sea lions to increased prey availability were those that incorporated random variation among years, suggesting that abundance of prey species is not the only variable affecting intake of prey by NZ sea lions. Resource competition or habitat destruction imposed by fisheries could restrict intake by sea lions, or force prey shifts to species not commercially harvested. Lastly, I investigated age-related survival and breeding probability of NZ sea lions with reference to the amount of main prey species in the diet over time. Models were run to test the relationship between each prey type, and breeding and survival probabilities over time. Survival probability is best explained by the null model, indicating that survival is not significantly affected by the amount of any one prey type in the diet. Smallscaled cod and hoki have the best predictive capacity after the null; hoki was correlated with an increase in survival for all age groups, while smallscaled cod predicted an increase in survival for all age classes except individuals over 15 years. In contrast, breeding probability is better explained by the amount of hoki and ling in the diet than by the null model. Consequently, the estimated finite rate of increase (λ) of the sea lion population rises with increased hoki in the diet. λ was estimated to be < 1 (population decline) under observed conditions (hoki found in 0-15% of scats depending on year), but λ was extrapolated to become >1 (population increase) if hoki were sufficiently abundant to be found in 35% of scats, a level that may have been reached historically (pre 1988). Similarly, λ was extrapolated to become > 1 if ling was found in > 30% of scats. The greater effect of prey types on breeding over survival makes biological sense when resources may be limiting population growth. Adult female NZ sea lions limited by prey availability may have enough food to survive but may choose not to invest in energetically expensive breeding. This would buffer the observed effect on survival since we would re-sight individuals that are alive but perhaps not in body condition to breed. If valuable prey stocks like ling and hoki continue to decline in the diet we could also see a significant impact on survival. Hoki has begun to recover but stock levels are still low in the Auckland Islands’ region (MPI 2013).
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    A study of brain injury in New Zealand sea lion pups : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand
    (Massey University, 2011) Roe, Wendi Dianne
    The New Zealand sea lion (Phocarctos hookeri) is a threatened species endemic to New Zealand. The majority of breeding in this species occurs on the Auckland Islands in the sub-Antarctic, and recent population estimates indicate that pup production is declining. Trauma is a significant cause of mortality in New Zealand sea lion pups, and much of this is believed to be caused by adult and subadult males, that bite, crush, shake and throw young pups. In this thesis, a number of techniques are used to determine the role played by traumatic brain injury in the mortality of NZ sea lion pups. The findings of gross necropsy examinations show that pups have numerous lesions indicative of traumatic brain injury, including skull fractures and subdural haemorrhages, and that pups die due to crushing and impact injuries. Although some pups have gross lesions considered in human paediatric medicine to be indicative of shaking injury, detailed histological and microbiological studies of sea lion pups show that most of these are associated with meningitis due to Klebsiella pneumoniae. This bacterium is a common cause of pup mortality. Immunohistochemical techniques are used to demonstrate that axonal injury is common in sea lion pups, but show that shaking is not a common mechanism of this pathological process. Instead, most axonal injury is found to be due to hypoxia-ischaemia, and evidence that raised intracranial pressure has occurred is comparatively common in dead pups. The combined findings of histological and immunohistochemical studies suggest that lesions such as optic sheath haemorrhage, intracranial subdural haemorrhage, spinal sub-meningeal haemorrhage, and optic nerve axonal injury could be caused by pertubations to vascular, intra-ocular, intracranial and subarachnoid pressure rather than being a direct result of trauma as is proposed in shaken baby syndrome.