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Start date: 2022Subject: search.filters.subject.Geographical distribution

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    Studies of the life history of school sharks (Galeorhinus galeus) : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Ecology at Massey University, Albany, New Zealand
    (Massey University, 2025-09-26) Burton, Alex J. C.
    The school shark (Galeorhinus galeus) is a globally distributed, migratory species that was recently reclassified, globally, as Critically Endangered due to all but the New Zealand population having collapsed due to overfishing. Effective management and recovery of these populations is currently limited by a lack of accurate biological information, which is increasingly difficult to obtain due to the scarcity of school sharks throughout their range. By studying the last stable school shark population, located in New Zealand, the aim of this thesis is to provide accurate information on the biology of school sharks to better inform their management worldwide. Specifically, this thesis examines allometric relationships, inter-population variation in life-history stage transitions, intra-population variation in juvenile growth rates, extent of the transfer of elements from mother to pups, and the spatio-temporal connectivity of habitats important to life-history. To enable better standardisation of length data when combining datasets, the optimal model for converting between different length measurements of school sharks was first identified. After standardising length and life-history stage data, a novel Bayesian generative classifier model suggested that length at life-history stage transitions varied among several, globally distributed, school shark populations. A study of juvenile school shark growth across several regions in New Zealand (i.e., Kaipara Harbour, Tasman and Golden Bays, and the Canterbury Bight) revealed that somatic (increase in body length with age) and hepatosomatic (increase of energy stores in the liver with age) growth was consistent among regions, but body condition was generally greater in the Canterbury Bight compared to other two regions. Tracking the year-long, three-dimensional movements of large female school sharks tagged in the Kaipara Harbour with satellite tags showed these sharks dispersed to several potentially important reproductive and feeding habitats around New Zealand. Finally, nutrients and essential and non-essential elements maternally provided to developing young were likely sourced from those assimilated from the mother’s diet during vitellogenesis. This thesis has national and international implications for school sharks and other elasmobranch species, as it provides information and techniques crucial to better understanding the biology of species that is needed to inform more effective management and recovery efforts.
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    Population dynamics and anthropogenic threats to New Zealand fur seal (Arctocephalus forsteri) in New Zealand : a thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Veterinary Science at Massey University, Palmerston North, Aotearoa New Zealand
    (Massey University, 2025) Hall, Alasdair
    New Zealand fur seals (Arctocephalus forsteri; ‘NZFS’) are New Zealand’s most encountered pinniped. However, substantial gaps exist in the knowledge of their abundance and distribution. This study provides NZFS abundance and distribution data for Kaikōura and Banks Peninsula and investigates anthropogenic risks in both locations. Additionally, the thesis undertakes the first nationwide NZFS abundance estimate in ca. 50 years. The Kaikōura population study was the first since the 2016 earthquake. Kaikōura’s NZFS population has grown and spread post-earthquake, with an upper population estimate of 21,560 – 28,327 NZFS in the 2022/23 breeding season. However, pup production at Ōhau Point, the most impacted colony, has not grown, and breeding distribution has changed significantly. Following earthquake damage, State Highway 1 (SH1), which runs close to NZFS colonies, was reconstructed. This study detected an almost fivefold increase in the annual number of NZFS recorded on SH1 from 2012 – 2022, compared to 1996 – 2005. Ten statistically significant NZFS incident clusters were located, representing 89% of the incidents. Cluster location shifted following post-earthquake road reconstruction. Monthly NZFS incident numbers were significantly positively associated with traffic and windspeed, and significantly negatively associated with temperature and rainfall. Road-abutting NZFS breeding explained most of the spatial variation in NZFS incidents. An abundance estimate of 13,147 – 17,675 NZFS was calculated for Banks Peninsula in 2023/24, and 25 previously unrecorded colonies were assessed. This study considered response strategies for an oil spill impacting Banks Peninsula’s NZFS, as the region is classified as ‘high risk’ for such incidents. Priority response strategies include preventing oil from reaching colonies, and hazing individuals away from waterborne slicks. From the most recently available count data, a minimum nationwide population estimate of 131,338 – 168,269 NZFS was calculated. Using recent counts and stage-structured population modelling, a more reliable estimate of 181,646 – 239,473 NZFS was calculated, a substantial increase on the most cited nationwide abundance figure, 100,000 NZFS. This thesis’ population findings provide useful baselines and highlight the need for improved NZFS population monitoring. This is particularly important due to the changing human-NZFS relationship, evidenced by the Kaikōura road reconstruction and the risk of oil spills in Banks Peninsula.
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    Wild bovid habitat and infectious disease risk in Thailand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, School of Veterinary Sciences, Massey University
    (Massey University, 2024-11-07) Horpiencharoen, Wantida
    Wild bovids are a diverse group of typically large, hoofed ruminant mammals that play crucial functions in ecosystems as seed transporters and prey for predators to maintain biodiversity. However, their conservation status varies from least concern to critically endangered with extinction, depending on the regions and remaining population. The expansion of agricultural areas and livestock farming has led to habitat loss and natural resource sharing, likely increasing the risk of disease transmission and pathogen circulation between humans, wildlife, and domestic animals at the shared habitats or the interface areas. This thesis aims to identify the habitat suitability of five wild bovids remaining in Thailand, understand the consequences of introducing infectious disease into the population, and identify where there is a risk of disease transmission. Therefore, three main studies were conducted: 1) identifying suitable areas for five wild bovid species, including gaur, banteng, wild water buffalo, mainland serow and Chinese goral in Thailand; 2) simulating the impact of infectious diseases of cattle on wild bovid populations, and; 3) mapping potential risk areas between wild bovids and cattle. Initially, I used ecological niche modelling to identify the habitat suitability of five wild bovids remaining in Thailand. Due to poor model predictions for two species (mainland serow and Chinese goral), I excluded these two models from further analyses. The results indicated that over 50% of the potentially suitable areas for the three modelled species (gaur, banteng, wild water buffalo) were located outside protected areas close to human populations and agricultural areas. Then, I simulated the number of animals in a model gaur population with and without infections over 100 years with 100 repetitions using stochastic mathematical models. I selected six bovine infectious diseases with different traits, such as incubation and infectious periods or fatality probabilities, including anthrax, bovine tuberculosis, haemorrhagic septicaemia, lumpy skin disease, foot and mouth disease and brucellosis. I introduced an individual infected animal into a closed population for each infectious disease. The disease-free gaur population grew over time, with infections with different traits having different impacts. The populations infected with chronic diseases (e.g. bovine tuberculosis and bovine brucellosis) showed the greatest decline, while diseases with high mortality but acute disease or high transmission rates with low mortality had less impact on the populations. Finally, I mapped the potential risk areas for disease transmission, assuming that high cattle density and habitat suitability increased transmission risk between wild bovids and livestock. The results also indicated that the potential high-risk areas were at the interface areas at the forest edges where interactions between wildlife and cattle occur. All my studies and findings will require further investigation and validation to gain a deeper and better understanding of the complexity of infectious diseases within wildlife populations and the dynamics of their distributions, but they contribute to supporting wildlife conservation and implementing disease mitigation measures to prevent disease transmission among the populations by highlighting where wild bovids might have suitable habitat, what types of infections may be problems and where mitigation may be better targeted.
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    Historical biogeography of marine ray-finned fishes (Actinopterygii) of the Southwest Pacific : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Marine Evolutionary Ecology at Massey University, Auckland, New Zealand
    (Massey University, 2023) Samayoa, André Philippe
    Current environmental and anthropogenic pressures are driving significant biodiversity loss and range shifts in marine environments. Understanding how biodiversity is generated and how it responded to past environmental changes is fundamental to inform future management strategies for marine resources. As the largest ubiquitous taxonomic group among marine vertebrates, ray-finned fishes (Actinopterygii) represent the best model to understand the generation of biodiversity and the processes that shaped contemporary geographic patterns in the sea. In this sense, centers of marine endemism are of evolutionary value as they translate evolutionary and ecological mechanisms that drive biodiversity dynamics. In the Pacific Ocean, endemism centers for marine fishes are mainly located in remote oceanic islands at the periphery of the tropical West Pacific which harbors the highest levels of biodiversity. Biogeographic research suggests that marine fish endemism in the oceanic islands of the Central Pacific originated via multiple independent jump-dispersal colonization events, and that the islands have acted as sources of new unique biodiversity. However, as the evolutionary setting starts to be revealed for marine fish endemism in the Pacific, processes that generate and maintain biodiversity in other peripheral islands remain unknown. My thesis aims to fill this gap by studying the origin, evolution, and processes that have shaped endemism and biodiversity of marine fishes in the Southwest Pacific. I examined the historical biogeography of the region´s marine fish fauna using open-access molecular data to infer evolutionary histories, and geographic distribution information to assess spatial patterns of endemism and biodiversity. Data were analyzed across three research projects based on time-calibrated phylogenies, probabilistic biogeographic modeling, and statistical analysis of phylogenetic measures of endemism and biodiversity. My results confirm the role of the subtropical islands of the Southwest Pacific as sources of new unique biodiversity, identify mainland Australia as the major source of endemic lineages, highlight the significance of jump-dispersal and vicariance in shaping endemism patterns, and reveal that the processes shaping patterns of endemism and biodiversity differ at local scales. My thesis contributes to the understanding of unique contemporary biogeographic patterns in the marine fish fauna of the Southwest Pacific.
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    Range shifts and the population dynamics of tropical, subtropical, and rare fishes in New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Auckland, New Zealand
    (Massey University, 2022) Middleton, Irene
    The rate of species re-distribution during the Anthropocene is unprecedented. The expectation is that as global temperatures continue to rise, tropical regions will become increasingly inhospitable, and temperate regions will become more tropicalised and biodiverse as species track favourable conditions poleward. Climate change mediated range shifts are causing the distinctness of species assemblages and biogeographic regions to erode, and the most significant biodiversity changes are currently occurring in the coastal marine environment. Identifying the species currently undergoing range shifts and predicting where and when future climate-mediated range shifts will occur is critical to proactively manage changes in resource-based human livelihoods and meet conservation goals. However, identifying range shifts is often hampered by a lack of baseline distributional data. In the marine environment, large areas remain under-surveyed, and given that marine species are often cryptic, wide-ranging, and highly mobile, our knowledge of geographic distributions is far from complete. This thesis aimed to fill this knowledge gap by using a combination of novel data sources and methods to set an accurate baseline for the spatio-temporal distribution of tropical, subtropical and rare teleost fishes in a temperate marine setting and develop methods to allow us to monitor future biodiversity change. Teleost fishes are valuable indicators of current and future change; they are early responders to climate-mediated ocean warming and are charismatic and highly visible, increasing the ease of monitoring, particularly by citizen scientists. First, data sourced from published accounts, scientific surveys, commercial catches, and citizen science sources were examined to determine the spatio-temporal distribution of tropical, subtropical, and rare fish in NZ waters. I characterise their contribution to New Zealand’s marine biodiversity and set a baseline for future monitoring of climate-driven biodiversity changes. I found that the contribution of tropical, subtropical, and rare fishes to New Zealand biodiversity is significant, and their occurrences and diversity have increased over the past 50 years. Second, I present and test a novel method that combines citizen science with expert knowledge to classify out-of-range occurrences for marine fishes as potential range extensions or human-mediated dispersal events. The stepwise approach uses qualitative decision making and scoring tools to classify citizen science observations of tropical, subtropical and rare fishes and combines these classifications with expert validation to increase confidence. By applying the method to a range of focal species, I successfully identified species that had undergone range shift into or within New Zealand waters and one species whose range shift was facilitated by human-mediated dispersal. The ease of our approach and the intuitive outputs should appeal to managers and science practitioners concerned with climate-induced biodiversity changes and alien species detection. Third, I apply the classification methods and distributional baselines from Chapters 2 and 3 to citizen science occurrence data for tropical, subtropical and rare fishes in New Zealand waters to identify those species that are tohu (indicators) of change and identify the areas where biogeographic change is occurring. Labrids and Pomacentrids disproportionately contributed to out-of-range occurrences, and 87% of all out-of-range occurrences represented potential and actual range extensions. Locations with a high occurrence of potentially range shifting fishes were centred in north-eastern New Zealand, with occurrences of potentially range shifting fishes decreasing with increasing latitude. I surmise that climate-mediated biodiversity change in New Zealand fishes is occurring and present a list of species contributing to range shifts by region to facilitate effective monitoring and impact mitigation. Overall, this thesis contributes new knowledge regarding the rate of poleward climate-mediated range shifts of marine teleost fishes to New Zealand and a suite of novel tools to facilitate future monitoring and impact mitigation of climate-mediated range shifts. I successfully demonstrate the capacity of ocean-going citizen scientists to identify range shifts in the marine environment and overcome some of the common biases and sampling errors associated with citizen science data by incorporating expert validation and knowledge. My results suggest that New Zealand is currently not a hotspot for climate-mediated biodiversity shifts but biodiversity shifts are occurring and the contribution of tropical, subtropical and rare fishes to New Zealand diversity is increasing. These contributions of this thesis will provide a baseline and framework for resource managers, science practitioners and citizens, to monitor range shifts and manage the impacts of climate change on New Zealand’s marine ecosystem.