List of Titles

Catchment and River Management in Graduate Teacher Education: A Case Study of Student Teacher Learning and Teaching in the Upper uThukela Valley, KwaZulu-Natal

- Heath, Gavin Edward Craig

Authors: Heath, Gavin Edward Craig
Date: 2021-10-29
Subjects: Geography Study and teaching (Higher) South Africa KwaZulu-Natal , Watershed management Study and teaching (Higher) South Africa KwaZulu-Natal , Pedagogical content knowledge , Environmental education South Africa KwaZulu-Natal , Teacher effectiveness South Africa KwaZulu-Natal , Curriculum and Assessment Policy Statement (CAPS)
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/190635 , vital:45012 , 10.21504/10962/190635
Description: This study developed as a progressive focus on a design research process towards the inclusion of new environmental knowledge in teacher education. It is centred on the clarification of pedagogical content knowledge for the teaching of catchment and river management in Geography teacher education. The study was developed as a design research case study with three phases or iterations of experiential engagement and data collection during the teaching of Postgraduate Certificate in Education students at the University of KwaZulu-Natal where I lecture Geography Education. The study’s iterative design was developed around pedagogical content knowledge refinement with curriculum knowledge analysis (phase 1) that was followed by lecture delivery and analysis (phase 2) and analysis of student engagement during fieldwork, and on teaching practice in rural classroom contexts (phase 3). Data and insights were generated across the successive stages of knowledge differentiation and teaching and learning interactions over time, and included reflection with students involved in the lectures, fieldwork and teaching practice programme. The analytical work covered a review of trajectories in new environmental knowledge, social-ecological systems, sustainability competencies, practice architecture and fieldwork pedagogy. This was done using three research lenses, namely social-ecological systems, social learning and practice architectures. All the design research and review processes served to develop, clarify and refine pedagogical content knowledge for sustainability-oriented teacher education. Thus the study conformed to the tenets of design-based research that was centred on clarification and review of pedagogical content knowledge that was carried into phases two and three. Research was focused at the nexus of pedagogical content knowledge and sustainability concerns that is necessary for the teaching of catchment and river basin management within a social-ecological systems perspective for integrated water resources management in South Africa and globally. The findings informed an illustrative model on how the research was carried out. Six design research insights and principles conclude the study and encapsulate the contribution it makes to new knowledge on how teacher education practice can be progressively aligned with new content knowledge teaching and the teaching of sustainability concerns. Specific findings in the form of six research insights indicated that the fieldworkbased teaching practice experience proved a successful learning crucible to develop sustainability competences. The cohort of student teachers passed their fieldwork teaching practice despite inadequate covering of foundational concepts in school and university. The teaching of a catchment management strategy case study was valuable in all three phases of research. A multi-contextual teaching and learning environment was successfully negotiated and navigated by the student teachers. The present Curriculum and Assessment Policy Statement does not speak to the reality on the ground, particularly in deep rural environments. A compulsory virtual Geography teacher training experience is recommended. Lastly, varied and broad responses to the noted multi-contextual challenges are needed in order to prepare and equip student teachers for the demands of the new environmental knowledge in the curriculum. Based on the groundwork provided by this study, there is scope for further research especially regarding the varied and broad responses to this new environmental knowledge in the curriculum. , Thesis (PhD) -- Faculty of Education, Education, 2021
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Baseline description of the Benthic Biotopes for two Long-Term Ecological Research (LTER) stations in Algoa Bay, Agulhas ecoregion, South Africa

- Parker-Nance, Shirley

Authors: Parker-Nance, Shirley
Date: 2021-10-29
Subjects: Benthic ecology South Africa Algoa Bay , Long-Term Ecological Research Program , Marine invertebrates South Africa Algoa Bay , Reef ecology South Africa Algoa Bay , Coastal zone management South Africa Algoa Bay , Reef fishes South Africa Algoa Bay , Ecological mapping South Africa Algoa Bay
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/191680 , vital:45147 , 10.21504/10962/191680
Description: Shallow coastal marine ecosystems provide important resources to society but are increasingly under threat from anthropogenic impacts. These systems form an interface between land and sea, providing valuable resources. Global environmental change, overexploitation, habitat transformation, pollution and policies aimed at short-term socio-economic gains are driving the loss of natural resources, productivity and biodiversity. Consequently, a comprehensive and holistic understanding of the current and future states of marine ecosystems is essential. This requires insight into the processes involved in maintaining genetic, species, habitat, community and biotope diversity at an ecosystem level. An understanding of ecosystem processes and the ability to detect changes in biodiversity, biotopes, seascape composition and ecosystem functioning require observation made over time and space. In response to this need, Long-Term Ecological Research (LTER) programmes such as those established by the South African Environmental Observation Network (SAEON) supported by the Department of Science and Innovation’s (DSI) Shallow Marine and Coastal Research Infrastructure (SMCRI) collect long–term observational data from different environments and systems. This study aimed to evaluate data collected as part of the developmental phase of a newly established benthic research platform. The datasets constructed are used to develop a baseline description of the benthic biotopes of two study areas within Algoa Bay. It aimed to gain insight into the feasibility of the methods used and the value of the data and derived essential biological variables (EVB). Assessing the sustainability of the programme over time was done through a practical evaluation of the methodology to be used and the technical feasibility of data collection and analysis. It furthermore aimed to assess the data usefulness in describing biodiversity at various scales and its sensitivity in reporting change. This pilot study provides valuable insight into data collection methodologies and introduces new sampling platforms. The baseline dataset consisted of data collected during the first 18 months of the SAEON Benthic Ecosystem Long-Term Ecological Research (BELTER) platform in Algoa Bay, Agulhas ecoregion, Western Indian Ocean, South Africa. This comprised of the collection of images for 150 m2 of the researched benthic seascape and 306 stereo video data streams. The 77 760 point dataset allowed the identification of 12 substrate types, 7 biotopes, 44 sub-biotope units, 377 sessile and sedentary benthic species and 51 ichthyofauna species. The described habitat and benthic communities and the defined benthic biotopes allowed for the assessment of biotope heterogeneity and the construction of a provisional distribution map for the broader biotopes. This work includes a study into the infra- and supra-benthic ichthyofauna associated with the defined biotopes and investigates the role habitat and benthic communities play in the distribution of these fish 3 assemblages. Lastly, it assesses the value of morphological traits and diversity indices for describing and comparing abiotic and biotic components of observed systems within the shallow coastal marine seascape. This study shows that species composition differs significantly between biotopes with habitat type playing a key role in the composition of the benthos. Substrate type, consolidated or unconsolidated, depth and the composition of the soft sediment is the most important determining factors. The White Sands Reef station has a higher species diversity than the St Croix Island Complex station with a higher percentage cover associated with the hard substrate. The dissimilarity between biotopes and communities are generally high although similarity within the biotopes or communities was found to be relatively low. This was considered indicative of high heterogeneity within the biotopes and a patch or mosaic-like distribution of communities within the broader biotope. A fine-scale a posteriori analysis of the data collected confirmed the high heterogeneous nature of both habitat and communities within the broader biotope. The description of the abiotic and biotic variables resulted in the identification of a diverse suite of biotope subunits. The character of the biotope hinges not only on the composition of the substrate and biota present but the contribution of smaller distinct biotopes subunits, their distribution and representation within broader biotopes and the degree these are shared with other broader biotopes. The distribution of these biotope units at different scales is believed to be important in understanding inherent diversity, niche partitioning and connectivity within a highly heterogeneous seascape. Ichthyofauna associated with the broader biotopes were indicative of the substrate type. Low profile reef systems with interspaced sandy stretches supported both reef fish and those typically associated with sandy substrates. Benthic biotopes associated characteristically with higher profile reef systems and less sand or soft sediment were mainly utilized by reef-associated fish species. Substrate type, depth and seasonality were found to be important factors in the observed composition and distribution of ichthyofauna over the seascape. Although fish species were found to have a wide distribution and made use of multiple biotopes the average abundance of the species within the observed assemblages differed. Analysis of ichthyofauna species composition indicated that observed fish assemblages were homogeneous within five of the seven biotopes. Broader biotopes that were found to be significantly different between sample locations are characterised by a diverse complement of biotope subunits and are highly heterogeneous. Traits and diversity indices are important tools for assessing and comparing different systems within the seascape, both spatially and temporally. The classification of the biota into broader phylogenetic groups indicated a significant difference between biotopes. This is especially useful when detailed 4 analysis or species identification is not possible or the skill set is not available. Morphological traits included in this study informed on the physical structure of the communities present and in combination with substrate type provided insight into the three-dimensional structure of the biotope. Species diversity, abundance, density estimates and the Shannon-Weiner diversity index were found to be the most useful diversity indices characterising and comparing biotopes. This was less so for ichthyofauna. Significant differences in the number of species observed were evident only between consolidated and unconsolidated dominated substrates. Although there was no significant difference in the number of individuals observed, both the Shannon-Weiner and Simpson Diversity indices were able to highlight differences in the fish assemblages observed for the different biotopes. The data collected, although permitting a comprehensive baseline assessment of the benthic environment for two research stations within the SAEON Algoa Bay LTER Sentinel Site, is temporally limited. The ichthyofauna dataset used was small and it is understood that the addition of length-frequency analysis of observed ichthyofauna will benefit our understanding of the biotope use by infra- and supra-benthic fish species over their life history within the larger seascape. Seasonal differences were evident and it is expected that datasets spanning several years, including LTER stations within different marine ecosystems types, will provide valuable insights on system dynamics in the short and long term both spatially and temporally. This study is the first attempt to evaluate the methodology developed and data collected in the South African Environmental Observation Network’s, Elwandle Coastal Node as part of the Shallow Marine and Coastal Research Infrastructure Benthic Ecosystem Long-Term Ecological Research (BELTER) platform. Newly designed and developed sample equipment and a sampling regime allowed for the collection of data on a long-term basis. The study was successful in the description of the biotope and biotope subunits for two research stations in Algoa Bay. It permitted the construction of comprehensive species lists for both benthic sessile and sedentary biota and the associated ichthyofauna. The subset of data used was successful in reporting on both spatial and temporal change. This work demonstrates that in the absence of detailed species identifications, traits may be used to describe habitat and community structure and report on abiotic and biotic biotope characteristics. This study furthermore allowed for the comparison of a comprehensive suite of diversity indices highlighting indices that may be especially useful in routine BELTER reporting. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
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Competing policy imperatives in Post-Apartheid South Africa: An analysis of the effects and larger significance of ESKOM restructuring on the South African automotive industry, 2005-2014

- Sibuyi, Lucas Nkosana

Authors: Sibuyi, Lucas Nkosana
Date: 2021-10-29
Subjects: Eskom (Firm) , South Africa Colonial influence , Electric power Conservation South Africa , Electric utilities Government ownership South Africa , Electric utilities Privatization South Africa , Import substitution South Africa , Government business enterprises South Africa
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/192911 , vital:45278 , 10.21504/10962/192911
Description: The state has played an indispensable, major role in the industrialisation of South Africa, and its transformation from an economy of agriculture and mining to one based on manufacturing and services by the 1970s. Large state-owned corporations in communications and transportation, finance, industry and power have been key to this process, which also involved an extensive (and racist form of) import substitution industrialisation (ISI) from the 1920s. The 1970s saw a shift towards neoliberal policies, first under the National-Party-led apartheid government and then under the African-National-Congress-led democratic government formed in 1994. Since the 1980s, this restructuring has profoundly affected state-owned enterprises (SOEs), including the monopoly electricity utility ESKOM, and manufacturing industries, such as the automotive sector. This thesis examines the evolution of and interaction between different areas of neoliberal policy, and their evolution over time through a consideration of the relationship between the restructuring of SOEs and manufacturing, with a focus on ESKOM and autotomotives respectively. Relying on interviews with senior officials, policymakers, union leaders and industrialists, as well as primary documents, the study examines the responses of OEMs in South Africa (BMW, Ford, General Motors, Mercedes Benz/Daimler, Nissan, Toyota and Volkswagen) to ESKOM’s actions, and analyses the root of these actions. It argues that while restructuring has been framed by a common framework, policy development and implementation is not coordinated or cohesive. ESKOM, for example, gutted investment in electricity and maintenance generation capacity to become profitable and create space for Independent Power Providers (IPPs) – neoliberal measures for which it was rewarded and lauded. This took place at a time when national policy emphasised the need to grow manufacturing and attract direct investment by creating an investor-friendly climate resting on infrastructure. It also took place when the Department of Trade and Industry (DTI) rolled out highly successful plans – also praised and rewarded – to help adjust automotives to open markets; the sector grew much larger than under ISI, while other sectors like textiles collapsed. ESKOM’s measures, however, led to a rapid decline in the capacity and stability of the power system, and directly contradicted the drive to expand and globalise manufacturing, in which automotives was now the leading edge. Corruption in the utility worsened, much of it through subcontracting measures rooted in neoliberal reforms, but this did not cause the basic problems. It is argued that this situation of competing policy imperatives reflects deeper, long-term problems in the South African state, including contradictory policies, uneven capacity and a lack of coordination. For example, there was no coordination between the DTI and stakeholder departments that regulate ESKOM, being the shareholder ministry, the Department of Public Enterprises (DPE) and its policy ministry, and the Department of Mineral Resources and Energy (DMRE). These types of problems did not start postapartheid, and post-1994 reforms have not adequately addressed them. What exists is not a “developmental” state, as policymakers hope, but a fractured state of an intermediate type that combines “developmental” and “predatory” features in a oneparty dominant system in which lines between ruling party and state blur, and state resources are leveraged for elite class formation. Such was the case under apartheid skippered by the NP, with Afrikanerisation, and it continues today post-apartheid under the ANC with BEE. Major reforms are needed, but not just in SOE governance or budgets, as many have suggested. If we are to take the nation forward, the basic design of the state must be reformed. The state needs professionalised, coherent policy-making and implementation, proper coordination of state entities and hard decisions. It should manage high levels of public infrastructure, guarantee political stability and credit ratings, and provide policy certainty and predictability. Without big reforms it will remain a chronic underperformer. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
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Date Issued: 2021-10-29

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Application of environmental magnetism to trace sediment sources contributing to Kruger National Park reservoirs

- Miller, Jordan Katherine

Authors: Miller, Jordan Katherine
Date: 2021-10-29
Subjects: Geomagnetism South Africa Kruger National Park , Sediments (Geology) South Africa Kruger National Park , Sedimentation and deposition South Africa Kruger National Park , Petrology South Africa Kruger National Park , Sediments (Geology) Magnetic properties South Africa Kruger National Park
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/192842 , vital:45269 , 10.21504/10962/192842
Description: Sediment source fingerprinting using environmental magnetism has successfully differentiated between sediment sources in different regions of South Africa. The method was applied in the natural landscape of the Kruger National Park to trace sediment sources delivered to four reservoirs (Hartbeesfontein, Marheya, Nhlanganzwani, Silolweni) whose contributing catchments were underlain by a range of igneous, metamorphic, and sedimentary rocks. This research attempted to evaluate the impact of vegetation, lithology, and particle size controls on the ability of magnetic signatures to discriminate between lithology-defined potential sources. Potential source samples were collected from each lithology present in all catchments, except for the Lugmag catchment where the lithology was uniform, but the vegetation type varied significantly between woodland and grassland. One sediment core was taken in each of the four catchment reservoirs where there was more than one lithology present in order to unmix and apportion contributing sediment sources. Sampling time in the field was often restricted to short periods, dependent on anti-poaching activities and movement of free-roaming wildlife across the Park. This occasionally led to the sub-optimal collection of enough source samples to capture source signature variability. Mineral magnetic parameters were unable to discriminate between vegetation-defined sediment sources in the Lugmag catchment (homogenous underlying lithology) but were able to discriminate between lithology-defined sediment sources (to varying degrees) in the other four catchments. The contributions of each lithology-defined sediment source were estimated using a straightforward statistical protocol frequently used in published literature that included a Mann-Whitney U or Kruskal-Wallis H test, mass conservation test, discriminant function analysis, and an (un)mixing model. A contribution from each lithology source to reservoir sediment was estimated. Connectivity was a significant factor in understanding erosion in each of the catchments. Both longitudinal (e.g., drainage density) and lateral connectivity (e.g., floodplain - river) were important. Travel distance of eroded sediment to reservoirs was also an essential element in two of the four catchments. There are no defined floodplains, so channel bank soils are very similar to the catchment soils. Therefore, channel bank storage potential would be similar to the storage potential within the catchment. Vegetation played a crucial role in protecting soils, by reducing ii erosion potential as well as trapping and storing sediment, thereby interrupting lateral connectivity. Underlying geology and soils are determining factors of vegetation type and density. A published study estimated catchment area-specific sediment yields for different KNP catchments, including the Hartbeesfontein, Marheya, Nhlanganzwani and Silolweni catchments. The published data was used in combination with the (un)mixing model source contribution estimates of this thesis to determine specific sediment yields by lithology, i.e., for each catchment source. The polymodal particle size characteristics of the sample material led to an investigation into particle size controls on the ability of magnetic signatures to discriminate between potential sources. Due to time constraints, only the Hartbeesfontein and Marheya catchments were tested for grain size differences. For each catchment, one bulk sample was created for each lithology source. This bulk sample was divided into 10 subsamples. The samples were then fractionated into four particle size fraction groups: coarse (250 – 500 μm), medium (125 – 250 μm), fine (63 – 125 μm), and very fine (<63 μm). Reservoir samples were also bulked to create 10 down-core samples for each reservoir, and the samples were also fractionated into the four fraction groups. The same statistical protocol was applied to the fractionated samples and contribution estimates were obtained by lithology for each particle size fraction group. The goodness of fit and uncertainty of the (un)mixing model varied in each catchment, with the two measures of accuracy often showing an inverse relationship. The fractionated modelling estimated the same primary source in the two catchments as in the unfractionated modelling. However, additional information on the secondary and tertiary sources was obtained. Connectivity remained a significant factor in interpreting the results of the fractionated analysis. Specific sediment yields were estimated for each catchment source per particle size fraction group. These sediment yields provided a deeper understanding of sediment transport through a catchment and which particle size groups are most important in catchment erosion. An original contribution to research was made by estimating source contribution estimates for the four reservoirs, quantifying sediment yields for each catchment lithology and then for each catchment lithology by particle size. Mineral magnetic tracing of the catchments was applied for the first time in this region of South Africa. , Thesis (PhD) -- Faculty of Science, Geography, 2021
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Date Issued: 2021-10-29

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Museums for the Planet: Critical Realist Philosophy and the Possibility of an Eco-decolonial Museology

- Jeffery, Thomas Carnegie

Authors: Jeffery, Thomas Carnegie
Date: 2021-10-29
Subjects: Museums Management , Critical realism , Ontology , Decolonization , Organizational change , Social ecology , Eco-decolonial
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/192692 , vital:45251 , 10.21504/10962/192692
Description: This study introduces dialectical critical realism into museology as a philosophical underlabourer for the development of new theoretical potentials for the transformation of museum practice. The idea of the museum is in a moment of fluidity evident in emergent decolonial and ecological perspectives and in the International Council of Museum’s process of redefinition of the museum. The potential to reimagine the museum lacks a coherent philosophical and theoretical foundation. The persistence of museological dualism separates the social from the ecological and absents the emergence of relational modes of thinking and practice. This study conceives an ecological-decolonial or eco-decolonial mode of museology that is disruptive of dualism and generative of relationality, and is thus generative of agency for deeper, more effective and enduring social-ecological justice. The core of this thesis is the development of the eco-decolonial mode of museology through the DCR onto-axiological chain or ‘MELD’ schema. At 1M a depth ontological analysis augmented by interviews with key informants establishes a dialectic of society and ecology in the museological context. 1M surfaces capitalism and the implicit neoliberal ontology of museology as deep causal mechanisms of the 2E persistence of museological human-nature dualism. The paradox of ‘emancipatory neoliberalism’ is a policy-practice contradiction that absents potentials for transformation of the museum and that is held in place by the grounding ontological activity of museology, collection. The 2E perspective on absences enables the emergence of new transformative pathways towards the 3L vision of the eco-decolonial mode of museology as a (4D) new way of thinking and working to resolve neoliberal restrictions. The fundamental 4D change envisioned for museum philosophy, theory and practice is an ontological transformation from traditionalist human-nature dualism to a progressive human-nature dialectic. A case study considers instances where museum workers exercised the agency to expand practice in this way. Future work using the expansive learning methodology of Change Laboratories will develop and implement the potentials generated by the onto-axiological chain for the eco-decolonial mode to bring real change to traditional, dualist museum practice, in order to ensure the relevance and the agency of the museum as a social structure in and for a changing world. , Thesis (PhD) -- Faculty of Education, Education, 2021
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Date Issued: 2021-10-29

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An interpretation of the deeming provisions in legislation in the context of a good tax system: a South African perspective

- Mostert, Tarita

Authors: Mostert, Tarita
Date: 2021-10-29
Subjects: Organisation for Economic Co-operation and Development , Taxation Law and legislation South Africa , South Africa. Income Tax Act, 1962 , Taxpayer compliance South Africa , Tax evasion (International law) , Deeming provisions
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/190897 , vital:45039 , 10.21504/10962/190897
Description: The goal of this thesis is to analyse the relationship between deeming provisions in legislation and the principles of a good tax system. The need for a positive relationship between deeming provisions and the principles of a good tax system is demonstrated in the thesis. The research explains the historical development of deeming provisions, legal principles relevant to the interpretation of tax legislation, as well as the principles of a good tax system. Approaches to the interpretation of legislation are then described and illustrated by means of case law. Following this, the research focuses on a selection of provisions in the South African Income Tax Act, 58 of 1962, to determine whether the deeming provisions included in the Act reflect the application of the principles of a good tax system. In addition to the analysis of the selected statutory provisions, related case law is discussed, again in relation to the deeming provisions. A discussion of deeming provisions in two publications of the Organisation for Economic Co-Operation and Development (OECD) – the OECD Model Tax Convention and the OECD Multilateral Convention to Implement Tax Treaty Measures to Prevent Base Erosion and Profit Shifting – follows, with an analysis of two related deeming provisions in the Income Tax Act, to illustrate the international approach to deeming provisions and the principles of a good tax system. Finally, the administration of tax legislation is discussed, together with organisations whose mission is to promote the principles of a good tax system in tax administration. The research is qualitative in nature and follows a legal doctrinal research methodology. This methodology is both reform-oriented and theoretical and focuses on understanding the application of the legal concepts: deeming provisions, legal principles and principles of a good tax system. The research concludes that, from a theoretical perspective, a positive relationship exists between deeming provisions in the Income Tax Act and the OECD Model Tax Convention and the principles of a good tax system, and therefore creates a positive environment for tax compliance. , Thesis (PhD) -- Faculty of Commerce, Accounting, 2021
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Date Issued: 2021-10-29

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Evaluating and predicting impacts of Australian redclaw crayfish Cherax quadricarinatus and Louisiana red swamp crayfish Procambarus clarkii invasions

- Madzivanzira, Takudzwa Comfort

Authors: Madzivanzira, Takudzwa Comfort
Date: 2021-10-29
Subjects: Cherax Africa , Procambarus clarkii Africa , Freshwater crabs Africa , Crayfish Zambezi River , Crayfish Food Zambezi River , Aquatic biodiversity Africa , Conservation biology Zambezi River , Fishing Catch effort Africa , Introduced freshwater organisms Africa , Fish populations Africa , Functional response (FR)
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/191137 , vital:45064 , 10.21504/10962/191137
Description: Freshwater crayfish have become one of the most widely introduced freshwater taxa globally. Crayfish introductions have not spared the African continent, which, apart from Madagascar, is naturally devoid of native freshwater crayfish. These introductions are of concern because invasive crayfish have generally been shown to cause strong impacts on recipient ecosystems outside Africa. This study therefore set out to compile up-to-date information regarding crayfish introductions in Africa, their pathways and distributions and to improve our understanding of the nature and magnitude of their environmental impacts. A systematic review revealed that nine crayfish species have been introduced into the continent with five of those, Astacus astacus, Cherax quadricarinatus, Faxonius limosus, Procambarus clarkii and Procambarus virginalis, having established naturalised populations in fourteen African countries (Chapter 2). The main driver of these crayfish introductions was to provide socio-economic benefits but there is limited evidence of success. The thesis further documents attempts made to address crayfish knowledge gaps in Africa, including standardisation of C. quadricarinatus sampling gear (Chapter 3), determination of the distribution of C. quadricarinatus in the recently invaded Upper Zambezi Basin (Chapter 4), and predicting ecological and socioeconomic impacts of two crayfish species that are spreading rapidly in Southern Africa, namely, C. quadricarinatus and P. clarkii (Chapters 5 – 8). To standardise C. quadricarinatus sampling methods in Africa, two methods used in Southern Africa were compared and the Promar® collapsible trap baited with dry pellets was recommended as the best approach for C. quadricarinatus abundance studies due to the high catch per unit effort (CPUE), probability of capture and the suitability of dry dog food as a standard bait. This standard approach was used for crayfish surveys in the Zambezi Basin to comprehensively determine the spread and establishment of C. quadricarinatus across the basin. The establishment of C. quadricarinatus in the Barotse Floodplain, Upper Zambezi Floodplains freshwater ecoregion was confirmed. Although the probability of capture and catch per unit effort (CPUE) of C. quadricarinatus in the Barotse floodplain were similar to that of older invasions in the basin (Lake Kariba and Kafue River), morphometric differences among C. quadricarinatus populations sampled from these invaded regions were detected. Although crayfish were not detected in other regions, for example, the Okavango Floodplains ecoregions, C. quadricarinatus have the potential to spread at a downstream and upstream rate of 49 and 12 km·year-1, impacting native biota therein. To evaluate the potential for ecological impacts, the consumer-resource dynamics of C. quadricarinatus and P. clarkii were described in comparison to a native trophic analogue, the freshwater crab of the Potamonautes genus, preying on various native taxa ubiquitous to African aquatic and terrestrial ecosystems. The use of functional response (FR) and consumption experiments in this study showed the potential impacts of the two crayfish species on native resources and on resources that support livelihoods in invaded ecosystems. This in most cases was a result of their high attack parameter, which also resulted in high functional responses ratios (FRRs) compared to native crabs. The crayfish FR, FRRs and consumption rates were mostly enhanced under the high temperature treatments. The FRs and consumption results were then combined with the field biomasses of crayfish and crabs to calculate the relative impact potential (RIP) to successfully predict the degree of impact caused by crayfish species relative to crabs. Crayfish species consistently displayed RIP scores > 1 relative to the native crab irrespective of region, which were higher for the summer than the winter season, suggesting greater impact of the invaders compared to the native species. This study further estimated the socioeconomic losses due to catch spoilage by C. quadricarinatus which are up to 1500 t per year in the invaded Kafue River Basin, which translates to an annual income loss of US$ 2 million. Information provided in this study is vital for conservation management and to compel policymakers to develop appropriate conservation management tools within regulatory frameworks, which could stop or minimise the spread of crayfish species and protect Africa from further losing aquatic biodiversity. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
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Date Issued: 2021-10-29

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Plant-fungal mutualism as a strategy for the bioremediation of hydrocarbon polluted soils

- Keshinro, Olajide Muritala

Authors: Keshinro, Olajide Muritala
Date: 2021-10-29
Subjects: Mutualism (Biology) , Plant-fungus relationships , Bioremediation , Mucilage , Plant exudates , Extracellular polymeric substances , Laccase , Peroxidase , Phytoremediation , Ligninolytic enzymes
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/190918 , vital:45041 , 10.21504/10962/190918
Description: Inasmuch as coal remains the linchpin for the generation of electricity and liquid petroleum products in South Africa, hydrocarbon waste and coal discard will continue to pose a threat to the environment. Therefore, the onus is on the associated industries to develop and implement efficient and sustainable strategies to mitigate the negative impacts of energy generating activities on the environment. Most conventional efforts in this regard, although successful for soil repair and the initiation of vegetation, have been deemed unsustainable. In an effort to find a sustainable remediation strategy a novel technology termed “FungCoal” was conceptualized and patented as a strategy for the rehabilitation of open cast coal mines, carbonaceous-rich spoils and coal wastes. This biotechnology, which exploits plant-fungal mutualism to achieve effective biodegradation of coal on discard dumps and the breakdown of the carbonaceous component in spoils, promotes revegetation to facilitate rehabilitation of mining-disturbed land. However, one limiting factor of the FungCoal bioprocess is that it requires oxidized weathered coal, a highly complex and variable resource for use as a co-substrate, for growth and proliferation of the coal degrading microorganisms. To fully exploit the potential of plant-fungal mutualism and its interaction for use in the remediation of coal contaminated soils, this study investigated the proposed relationship between plant roots, root exudate and the coal degrading fungus “Aspergillus sp.” (previously Neosartorya fischeri) strain 84 in more detail, in an effort to gain further insight into the mechanisms underpinning plant-fungal mutualism as a strategy for re-vegetation of coal discard dumps and the rehabilitation of hydrocarbon-contaminated soil using the FungCoal approach. A pot-on-beaker (PoB) method was developed for the easy cultivation and collection of extracellular polymeric substance (EPS)-containing exudates from Zea mays L. (maize) and Abelmuschus esculentus (okra). Characterisation of the EPS material from these exudates was carried out using a combination of physicochemical and biochemical methods. The results from analysis of phenolics and indoles showed that exudates contain some form of indoles and phenolic compounds, although in little proportions, which may fulfil a signalling function, responsible for attracting soil microorganisms into the rhizosphere. Spectroscopic analysis of the exudates using FT-IR revealed vibrations corresponding to functional groups of alkanes, alkenes, alkynes, and carboxylic acids. These compounds likely provide an easily accessible source of carbon to soil microorganisms and are also a better alternative to the poly-aromatics which are an inherent component locked-up in the supposed recalcitrant coal material. The results from biochemical analyses also revealed the presence of carbohydrate, proteins, lipids, and low amounts of α-amino-nitrogen in the EPS of maize and okra. These components of EPS are all essential for the stimulation of enzymatic activities in soil microorganisms and, which may in turn aid biodegradation. The action of the root EPS from maize was further tested on three coal-degrading fungal isolates identified as Aspergillus strain ECCN 84, Aspergillus strain ECCN 225 and Penicillium strain ECCN 243 for manganese peroxidase (MnP) and laccase (LAC) activities. The results revealed that the Aspergillus species, strains ECCN 84 and ECCN 225, showed with or without EPS, observable black halos surrounding each of the colonies after 7d incubation indicative of positive MnP activity, while no activity was observed for the Penicillium sp. strain ECCN 243. Analysis for LAC revealed little or no activity in any of the coal degrading fungi following addition of pulverized coal to the growth medium. Interestingly, the addition of EPS-containing exudate to the coal-containing medium resulted in increased LAC activity for all fungal isolates. This finding affirmed the positive contribution of EPS to extracellular LAC activity, purported as an important enzyme in the coal biodegradation process. Finally, the impact of plant-derived exudate on the colonisation and biodegradation of coal was investigated in situ using rhizoboxes, to simulate a coal environment, and was carried out for 16 weeks. Microscopic examination of coal samples after termination of the experiment showed fungal proliferation and attachment to coal particles. All of the rhizoboxes that contained plants had higher medium pH and EC, and the concentration of phenolics, indoles and humic acids was greater than that of control treatments. These observations indicated better rhizosphere colonisation, substrate biodegradation and humification. Therefore, root exudate appears to play a significant role in coordination of soil microorganisms within the rhizosphere and likely serves both as a scaffold for rhizospheric interactions by providing microorganisms with accessible carbon and as a likely ‘trigger’ for induction of coal-degrading enzymes such as fungal LAC for mobilisation of recalcitrant carbon. This study has shown that EPS exuded from roots of Zea mays together with coal degrading fungus Aspergillus strain ECCN 84 can alkalinise the coal substrate and facilitate introduction of oxygen, possibly as a result of increased laccase activity, and increase availability of nutrients (as indicated by higher EC) in a coal-polluted rhizosphere, to provide plants and their associated mycorrhizae and presumably other beneficial microorganisms a more mesic environment for sustained phytoremediation with enhanced rehabilitation potential. In conclusion, this study confirms the positive role of root exudate in mediating a mutualistic rehabilitation strategy involving plants and fungi such as the FungCoal bioprocess. , Thesis (PhD) -- Faculty of Science, Institute for Environmental Biotechnology, 2021
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Date Issued: 2021-10-29

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Reactor development and process optimisation for the bioremediation of phenolic wastewaters by trametes species

- Ryan, Daniel Reginald

Authors: Ryan, Daniel Reginald
Date: 2004-04
Subjects: Uncatalogued
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/191487 , vital:45103
Description: In many service industries, the source of a company’s value has shifted from capital to knowledge and ideas, the quality of which is dependent on its employees (Wooldridge, 2006). In fact, human resources can be considered part of factor conditions which can positively impact on a firm’s competitive context. This impact can ultimately translate into improved financial results (Porter and Kramer, 2002). There is therefore a growing interest in ways to attract and retain talent. According to the managers of many big companies, well communicated corporate responsibility practices can improve staff attraction as well as retention rates by improving morale (CSRwire, 2002). To explore this, a small, creative company in Johannesburg which engages in charity work was selected as a case study, with the goal being to understand whether their culture of good deeds has a positive impact on staff wellbeing. While the owner of the company actively attempts to make the company an enjoyable place to work at, he appears to have initiated the philanthropic activities in a true spirit of giving, rather than with the motive of engaging staff in order to make more money. Nevertheless, the researcher’s investigative stance is that of an enlightened egoist, and the study focuses on the business case of giving being beneficial to the giver (ultimately the company) in the long term, as well as to the recipient. While the danger of suggesting that philanthropy could be instrumentalised is acknowledged (Morton, 2004), the investigation explores the possibility because such evidence could persuade other companies to become more socially concerned. Through a qualitative approach involving interviews, observation and analysis of video footage, it becomes apparent that there is clearly value for the staff in the charity work they do. Unfortunately the multiple initiatives undertaken to keep staff morale high at the company make it impossible to establish a clear link between the philanthropy and overall wellbeing, but as the study was conducted in the phenomenological paradigm the main concern was with understanding the experience of participants. However, an unexpected finding was that the employees derive great satisfaction from using their professional skills for charity work rather than just donating money to the charity. They feel that their skills uniquely position them to make significant changes to the lives of others, which gives them a sense of pride and achievement that they don’t necessarily experience in their ordinary activities at work. On the basis of this, it is recommended that companies look to involve staff with projects that require their specific expertise when evaluating philanthropic initiatives. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2004
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Date Issued: 2004-04

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Tense and aspect in Xhosa

- Savić, Stefan

Authors: Savić, Stefan
Date: 2021-10-29
Subjects: Xhosa language , Xhosa language Grammar , Xhosa language Semantics , Xhosa language Tense , Xhosa language Aspect , Xhosa language Syntax , Xhosa language Morphology , Xhosa language Grammar, Comparative , Information structure
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/192897 , vital:45277 , 10.21504/10962/192897
Description: This dissertation investigates the semantics of each tense and aspect in Xhosa. Since tense and aspect perform important pragmatic functions, the analysis takes into account the correlation between the verb and the wider discourse in which it is embedded. Tense reflects the temporal relation between the time of the utterance (speech time) and an interval the speaker makes the assertion about (reference time). The Remote Past and the Remote Future tenses differ from their Recent/Immediate counterparts in that they denote events which occurred in a significantly different situation than the speech time and/or events in the surrounding discourse. Aspect does not only indicate the relation between the time occupied by the real world event and the reference time chosen by the speaker. The Perfective aspect represents an event as a unique change-of-state that pertains to a single point on the timeline which at the same time functions as the reference time. By contrast, for the Imperfective aspect temporally links the event to a contextually provided reference time, e.g. the utterance time, a time adverbial, a period of time previously introduced in the preceding discourse, or the interlocutors’ shared experience. At the pragmatic level, the Perfective aspect tends to introduce an event’s resulting state into the discourse, whereas the Imperfective aspect tends to rule it out. Like the Imperfective aspect, the Anterior and the Prospective aspects assert an event’s occurrence from a contextually defined reference time. They refer to the consequent and the preparatory states of an event, respectively. On the pragmatic level, the Anterior aspect may also indicate that the truth-conditionality of the event’s resulting state is contradicted in the immediate discourse. This study shows that tense and aspect temporally represent different means of temporally assigning an event to a particular portion of the timeline. I further argue that aspect indicates whether the reference time is provided in the context (Imperfective, Anterior, Prospective) or whether it is introduced by the verb itself (Perfective). Furthermore, this study shows that aspect exhibits a pragmatic function by laying focus on different parts of the event that are relevant in the upcoming discourse. , Thesis (PhD) -- Faculty of Humanities, Linguistics and Applied Languages Studies, 2021
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Date Issued: 2021-10-29

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A personality-based behavioural model: Susceptibility to phishing on social networking sites

- Frauenstein, Edwin Donald

Authors: Frauenstein, Edwin Donald
Date: 2021-10-29
Subjects: Phishing , Social networks , Personality , Self-presentation in mass media , Internet fraud , Internet users Habits and behavior , Big Five model , Human information processing , Heuristic-Systematic Model (HSM)
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/190306 , vital:44982 , 10.21504/10962/190306
Description: The worldwide popularity of social networking sites (SNSs) and the technical features they offer users have created many opportunities for malicious individuals to exploit the behavioral tendencies of their users via social engineering tactics. The self-representation and social interactions on SNSs encourage users to reveal their personalities in a way which characterises their behaviour. Frequent engagement on SNSs may also reinforce the performance of certain activities, such as sharing and clicking on links, at a “habitual” level on these sites. Subsequently, this may also influence users to overlook phishing posts and messages on SNSs and thus not apply sufficient cognitive effort in their decision-making. As users do not expect phishing threats on these sites, they may become accustomed to behaving in this manner which may consequently put them at risk of such attacks. Using an online survey, primary data was collected from 215 final-year undergraduate students. Employing structural equation modelling techniques, the associations between the Big Five personality traits, habits and information processing were examined with the aim to identify users susceptible to phishing on SNSs. Moreover, other behavioural factors such as social norms, computer self-efficacy and perceived risk were examined in terms of their influence on phishing susceptibility. The results of the analysis revealed the following key findings: 1) users with the personality traits of extraversion, agreeableness and neuroticism are more likely to perform habitual behaviour, while conscientious users are least likely; 2) users who perform certain behaviours out of habit are directly susceptible to phishing attacks; 3) users who behave out of habit are likely to apply a heuristic mode of processing and are therefore more susceptible to phishing attacks on SNSs than those who apply systematic processing; 4) users with higher computer self-efficacy are less susceptible to phishing; and 5) users who are influenced by social norms are at greater risk of phishing. This study makes a contribution to scholarship and to practice, as it is the first empirical study to investigate, in one comprehensive model, the relationship between personality traits, habit and their effect on information processing which may influence susceptibility to phishing on SNSs. The findings of this study may assist organisations in the customisation of an individual anti-phishing training programme to target specific dispositional factors in vulnerable users. By using a similar instrument to the one used in this study, pre-assessments could determine and classify certain risk profiles that make users vulnerable to phishing attacks. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2021
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Date Issued: 2021-10-29

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Distribution, ecological and economic impacts and competition of the invasive alien aquatic weeds (Pontederia crassipes Mart., Pistia stratiotes L., Salvinia molesta D.S. Mitch. and Azolla filiculoides Lam.) in Madagascar

- Lehavana, Adolphe

Authors: Lehavana, Adolphe
Date: 2021-10-29
Subjects: Pontederiaceae Madagascar , Water lettuce Madagascar , Salvinia molesta Madagascar , Azolla filiculoides Madagascar , Introduced aquatic organisms , Aquatic weeds Economic aspects , Aquatic weeds Social aspects , Aquatic weeds Geographical distribution
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/191225 , vital:45072
Description: In Madagascar, as in several countries in the world, the invasion by four aquatic weeds (Pontederia crassipes Mart. (Pontederiaceae), Pistia stratiotes L. (Araceae), Salvinia molesta D.S. Mitch Salviniaceae) and Azolla filiculoides Lam. (Azollaceae) are among the drivers of environmental and socio-economic deterioration in aquatic ecosystems. Pistia stratiotes was first recorded on the island in the 19th century, and P. crassipes from the beginning of the 20th century, while S. molesta and A. filiculoides were only documented during in the 21st century. From the 1920s, botanists such as Henri Perrier de la Bathie and Raymond Decary were already aware of the dangers caused, in particular by P. crassipes in other countries, and raised the alarm, but little attention has been paid to these species. The aim of the research conducted for this thesis was to determine the distribution, socio-economic and ecological impacts of these four invasive alien aquatic weeds in Madagascar and to make recommendations for their control. First, the distributions of these four aquatic weeds were mapped. This mapping exercise compiled data from different sources including herbarium records, online data and field visits across Madagascar. The mapping study was undertaken from August 2015 to June 2020. Except for mountainous areas above 1800 m (Tsaratanana Massif, Ankaratra Massif and Andringitra Massif) where no data were available, all of Madagascar's bioclimates were invaded by at least one of the four aquatic weeds. In total, at least one species was recorded in 18 of the 22 Regions. Pontederia crassipes was recorded in 13 Regions, S. molesta in 14 Regions, P. stratiotes in 12 Regions, and A. filiculoides in 13 Regions. Herbarium records revealed the oldest record for P. stratiotes to be 1847, 1931 for P. crassipes, 1995 for S. molesta and there were no herbarium specimens for A. filiculoides prior to the start of the current study in 2015. We now know where these four weeds occur and how abundant they are. An objective of this research was to assess the impacts of the four invasive aquatic plants on the socio-economy of the island, mainly on rice production and fishing. Between 2016 and 2019, 102 households in three regions, Soanierana Ivongo, Foulpointe and Antananarivo, were randomly selected and questioned on the impact of these weeds in their aquatic ecosystems and their livelihoods such as fishing and rice growing. Surveys revealed that the four aquatic weeds significantly threatened household activities. On the east coast of Madagascar, the invasions of these four invasive species decreased fish and freshwater shrimp production by 82%. On the high plateau of Madagascar, they reduced rice yield by 30% despite requiring an additional expense of US$ 1,107/ha for control. Although farmers surveyed only used manual control to manage these weeds, they were receptive to other control methods, including integrated control using herbicides and biological control. Another objective of this research was to determine the ecological impacts of the four weeds and specifically if freshwater ecosystem functioning would return after control. To assess the ecological impact, between February 2017 to August 2019, on Lake Antsokafina, the following abiotic and biotic factors were considered: physico-chemistry of water, succession of macrophyte community and animal diversity. With the exception of turbidity, the values of the physico-chemical parameters of the water (pH, electrical conductivity, water temperature and turbidity), were similar between the infested zone and cleared zone. A study on the invasion process of aquatic weeds showed that the plant community succession of the lake changed over time in the areas that had been cleared. The submerged species Ceratophyllum demersum was the pioneer, followed by creeping species such as Echinochloa colona and Ipomoea aquatica, before the area was recolonized by aquatic weeds. Among the aquatic weeds, S. molesta was the most aggressive, covering 92% of the area one year after the start of the experiment. For animal diversity, bird, shrimp and fish community were assessed. The cleaning of the plots in the lake allowed the resumption of fishing activity providing 50 to 200g/catch for shrimp and from 0.25 to 0.5kg/catch for fish per person per day, while no catch was obtained in the areas infested by aquatic weeds were fishermen still attempting to harvest fish/shrimp from the aquatic weed infested areas. Three species of birds, Humblot’s Heron (Ardea humbloti), the white-faced whistling duck (Dendrocygna viduata) and red-billed teal (Anas erythrorhyncha) returned once the areas had been cleared. A manipulated outdoor as descriptor for laboratory experiment was conducted to determine the level and nature of competition of four aquatic weeds species against the indigenous floating fern, Salvinia hastata Desv. (Salviniaceae), using an additive series density model. It was shown that all four invasive species outcompeted S. hastata, with P. crassipes being 24 times more dominant, followed by P. stratiotes at 12 times, S. molesta at 8 times, and finally A. filiculoides at 1.2 times more dominant. This study provided direct evidence of the biodiversity impact of these four species and thus also provided an environmental argument for their control. Based on the findings of this study, a series of recommendations was formulated to manage the invasions of alien species in Madagascar with particular attention to invasive aquatic weeds. These recommendations mainly concern the establishment of management structures and legal instruments such as the creation of a lead government agency at national level and a cross-sectorial invasive species advisory committee, which should review legislation and regulations related to invasive species. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
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Date Issued: 2021-10-29

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Modifcations to gravitational waves due to matter shells

- Naidoo, Monogaran

Authors: Naidoo, Monogaran
Date: 2021-10-29
Subjects: Gravitational waves , General relativity (Physics) , Einstein field equations , Cosmology , Matter shells
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10962/191118 , vital:45062 , 10.21504/10962/191119
Description: As detections of gravitational waves (GWs) mount, the need to investigate various effects on the propagation of these waves from the time of emission until detection also grows. We investigate how a thin low density dust shell surrounding a gravitational wave source affects the propagation of GWs. The Bondi-Sachs (BS) formalism for the Einstein equations is used for the problem of a gravitational wave (GW) source surrounded by a spherical dust shell. Using linearised perturbation theory, we and the geometry of the regions exterior to, interior to and within the shell. We and that the dust shell causes the gravitational wave to be modified both in magnitude and phase, but without any energy being transferred to or from the dust. This finding is novel. In the context of cosmology, apart from the gravitational redshift, the effects are too small to be measurable; but the effect would be measurable if a GW event were to occur with a source surrounded by a massive shell and with the radius of the shell and the wavelength of the GWs of the same order. We extended our investigation to astrophysical scenarios such as binary black hole (BBH) mergers, binary neutron star (BNS) mergers, and core collapse supernovae (CCSNe). In these scenarios, instead of a monochromatic GW source, as we used in our initial investigation, we consider burst-like GW sources. The thin density shell approach is modified to include thick shells by considering concentric thin shells and integrating. Solutions are then found for these burst-like GW sources using Fourier transforms. We show that GW echoes that are claimed to be present in the Laser Interferometer Gravitational-Wave Observatory (LIGO) data of certain events, could not have been caused by a matter shell. We do and, however, that matter shells surrounding BBH mergers, BNS mergers, and CCSNe could make modifications of order a few percent to a GW signal. These modifications are expected to be measurable in GW data with current detectors if the event is close enough and at a detectable frequency; or in future detectors with increased frequency range and amplitude sensitivity. Substantial use is made of computer algebra in these investigations. In setting the scene for our investigations, we trace the evolution of general relativity (GR) from Einstein's postulation in 1915 to vindication of his theory with the confirmation of the existence of GWs a century later. We discuss the implications of our results to current and future considerations. Calculations of GWs, both analytical and numerical, have normally assumed their propagation from source to a detector on Earth in a vacuum spacetime, and so discounted the effect of intervening matter. As we enter an era of precision GW measurements, it becomes important to quantify any effects due to propagation of GWs through a non-vacuum spacetime Observational confirmation of the modification effect that we and in astrophysical scenarios involving black holes (BHs), neutron stars (NSs) and CCSNe, would also enhance our understanding of the details of the physics of these bodies. , Thesis (PhD) -- Faculty of Science, Mathematics (Pure and Applied), 2021
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Date Issued: 2021-10-29

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