Foraging in a dynamic environment: movement and stable isotope ecology of marine top predators breeding at the Prince Edward Archipelago
- Authors: Carpenter-Kling, Tegan
- Date: 2020
- Subjects: Marine ecology , Stable isotope tracers , Estuarine ecology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49049 , vital:41596
- Description: Marine ecosystems are experiencing rapid changes due to climate change. The associated temporal and spatial changes in resource distribution impacts on the foraging behaviour of marine top predators. If these changes negatively affect the ability of marine predators to forage efficiently, there may be dire consequences for their populations. However, evidence of foraging plasticity during adverse conditions, or generalist foraging behaviour, can allow inference about the resilience of species to environmental change and provide essential knowledge towards effective and proactive conservation measures. I examined plasticity in the trophic ecology of 12 marine predator species breeding on Marion Island, southern Indian Ocean, over three years (2015 – 2018), a period characterized by pronounced environmental variability. Firstly, I correlated behavioural states inferred along the GPS tracks of incubating wandering, grey-headed, sooty and light-mantled albatrosses to environmental variables that are indicative of biologically productive oceanographic features. Secondly, I analysed δ13C and δ15N blood values in 12 marine predator species (the afore-mentioned albatrosses as well as king, gentoo, macaroni and eastern rockhopper penguins, northern and southern giant petrels and Antarctic and sub-Antarctic fur seals) over two seasons: summer and autumn. My results revealed that the foraging behaviour of all the species is, to some degree, either plastic (temporally variable isotopic niche) or general (large isotopic niche which remained similar over time), except for the king penguin (small isotopic niche which remained similar over time), a known foraging specialist. Furthermore, despite their dynamic foraging behaviour, resource partitioning among the predators was maintained over time. Due to the ease and relatively low cost of collecting tissues for stable isotope analysis it has the potential to be a powerful tool to monitor the trophic ecology of marine predators. I thus used my simultaneously collected dataset of GPS tracks with the stable isotope blood compositions to investigate some of the assumptions underlying the inferences made from marine predator δ13C and δ15N blood values. I reconstructed species- and guild- specific δ13C and δ15N isoscapes for eight seabird species. Following this, I coupled individual-based movement models of northern giant petrels with global marine isotope models to explore the sensitivity of tissue δ13C values to a range of extrinsic (environmental) and intrinsic (behavioural, physiological) drivers. My results demonstrate the strong influence of reference isoscapes on the inference of stable isotope compositions of marine predators. Furthermore, I show that caution should be used when using non-species-specific or temporally inaccurate isoscapes. I furthermore demonstrate that biological interactions, such as competition for food resources, either past or present, as well as spatio-temporal distribution of food patches strongly influence the foraging behaviour of marine predators. These findings highlight the importance of integrating biological interactions in species distribution models which are used to predict possible distributional shifts of marine predators in the context of global changes. My thesis further developed previously available methods and presents a novel approach to investigate sources of variance in the stable isotopic composition of animals’ tissues.
- Full Text:
- Date Issued: 2020
- Authors: Carpenter-Kling, Tegan
- Date: 2020
- Subjects: Marine ecology , Stable isotope tracers , Estuarine ecology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49049 , vital:41596
- Description: Marine ecosystems are experiencing rapid changes due to climate change. The associated temporal and spatial changes in resource distribution impacts on the foraging behaviour of marine top predators. If these changes negatively affect the ability of marine predators to forage efficiently, there may be dire consequences for their populations. However, evidence of foraging plasticity during adverse conditions, or generalist foraging behaviour, can allow inference about the resilience of species to environmental change and provide essential knowledge towards effective and proactive conservation measures. I examined plasticity in the trophic ecology of 12 marine predator species breeding on Marion Island, southern Indian Ocean, over three years (2015 – 2018), a period characterized by pronounced environmental variability. Firstly, I correlated behavioural states inferred along the GPS tracks of incubating wandering, grey-headed, sooty and light-mantled albatrosses to environmental variables that are indicative of biologically productive oceanographic features. Secondly, I analysed δ13C and δ15N blood values in 12 marine predator species (the afore-mentioned albatrosses as well as king, gentoo, macaroni and eastern rockhopper penguins, northern and southern giant petrels and Antarctic and sub-Antarctic fur seals) over two seasons: summer and autumn. My results revealed that the foraging behaviour of all the species is, to some degree, either plastic (temporally variable isotopic niche) or general (large isotopic niche which remained similar over time), except for the king penguin (small isotopic niche which remained similar over time), a known foraging specialist. Furthermore, despite their dynamic foraging behaviour, resource partitioning among the predators was maintained over time. Due to the ease and relatively low cost of collecting tissues for stable isotope analysis it has the potential to be a powerful tool to monitor the trophic ecology of marine predators. I thus used my simultaneously collected dataset of GPS tracks with the stable isotope blood compositions to investigate some of the assumptions underlying the inferences made from marine predator δ13C and δ15N blood values. I reconstructed species- and guild- specific δ13C and δ15N isoscapes for eight seabird species. Following this, I coupled individual-based movement models of northern giant petrels with global marine isotope models to explore the sensitivity of tissue δ13C values to a range of extrinsic (environmental) and intrinsic (behavioural, physiological) drivers. My results demonstrate the strong influence of reference isoscapes on the inference of stable isotope compositions of marine predators. Furthermore, I show that caution should be used when using non-species-specific or temporally inaccurate isoscapes. I furthermore demonstrate that biological interactions, such as competition for food resources, either past or present, as well as spatio-temporal distribution of food patches strongly influence the foraging behaviour of marine predators. These findings highlight the importance of integrating biological interactions in species distribution models which are used to predict possible distributional shifts of marine predators in the context of global changes. My thesis further developed previously available methods and presents a novel approach to investigate sources of variance in the stable isotopic composition of animals’ tissues.
- Full Text:
- Date Issued: 2020
Friction stir welding of thin section aluminium extrusions for marine applications
- Authors: Chikamhi, Prince Philhelene
- Date: 2020
- Subjects: Friction welding , Welding
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46030 , vital:39410
- Description: This dissertation focuses on the development of a welding extrusion feeder, tool and schedule for implementation of defect-free butt welds on long, thin and complex-shape aluminium extrusions, as used by the marine industry. Viability of employing Friction Stir Welding (FSW) as a welding technology for joining long extrusions with a short-bed and bolt-on feeder to facilitate onsite fabrication of flat structures in shipbuilding is evaluated. An FSW feeder, tool and process control unit were designed, developed and integrated with an existing FSW platform, to facilitate implementation of continuous welds. Weld data acquired from literature review, experimentation, mechanical testing and metallographic analysis was used in design considerations for the development of a feeder. Subsequently, butt welds were implemented successfully on long 3 mm AA6082-T6 extrusions, during continuous FSW on the feeder. A specially adapted tool, the Floating Bobbin Tool, used with the feeder to implement butt welds was designed and developed from literature tool heuristics and weld trials. The tool eliminated the need for a backing bar and enabled tool-workpiece auto-alignment, beneficial with thin-section extrusions. Effect of rotational and weld speed and tool geometry of two tools (Tool 1 and 2), on weld forces and quality was tested, to establish optimum parameters for attaining high quality welds. Tool geometry had a profound effect on weld forces and integrity; Tool 2 welds exhibited superior and consistent weld quality, meeting maritime rules and standards and proving the adequacy of using FSW for joining long thin extrusions. Feeder process control, automation and optimisation, was implemented by process control unit devices, in addition to force and position control provided by the existing FSW platform. Owing to process control, automation and optimisation during continuous FSW of thin long and complex-shape aluminium extrusions, welding setup times and process variations are minimised and chances for defect-free welds increased, boosting production and cost savings in large panel fabrication in shipbuilding.
- Full Text:
- Date Issued: 2020
- Authors: Chikamhi, Prince Philhelene
- Date: 2020
- Subjects: Friction welding , Welding
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46030 , vital:39410
- Description: This dissertation focuses on the development of a welding extrusion feeder, tool and schedule for implementation of defect-free butt welds on long, thin and complex-shape aluminium extrusions, as used by the marine industry. Viability of employing Friction Stir Welding (FSW) as a welding technology for joining long extrusions with a short-bed and bolt-on feeder to facilitate onsite fabrication of flat structures in shipbuilding is evaluated. An FSW feeder, tool and process control unit were designed, developed and integrated with an existing FSW platform, to facilitate implementation of continuous welds. Weld data acquired from literature review, experimentation, mechanical testing and metallographic analysis was used in design considerations for the development of a feeder. Subsequently, butt welds were implemented successfully on long 3 mm AA6082-T6 extrusions, during continuous FSW on the feeder. A specially adapted tool, the Floating Bobbin Tool, used with the feeder to implement butt welds was designed and developed from literature tool heuristics and weld trials. The tool eliminated the need for a backing bar and enabled tool-workpiece auto-alignment, beneficial with thin-section extrusions. Effect of rotational and weld speed and tool geometry of two tools (Tool 1 and 2), on weld forces and quality was tested, to establish optimum parameters for attaining high quality welds. Tool geometry had a profound effect on weld forces and integrity; Tool 2 welds exhibited superior and consistent weld quality, meeting maritime rules and standards and proving the adequacy of using FSW for joining long thin extrusions. Feeder process control, automation and optimisation, was implemented by process control unit devices, in addition to force and position control provided by the existing FSW platform. Owing to process control, automation and optimisation during continuous FSW of thin long and complex-shape aluminium extrusions, welding setup times and process variations are minimised and chances for defect-free welds increased, boosting production and cost savings in large panel fabrication in shipbuilding.
- Full Text:
- Date Issued: 2020
Functional conversion of commercial buildings in South Africa
- Authors: Kuliti, Gerald
- Date: 2020
- Subjects: Commercial buildings -- South Africa , Buildings -- Conservation and restoration Buildings -- Maintenance and repair
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46075 , vital:39485
- Description: In the major cities of South Africa, there is a prevalence of originally built commercial buildings that are being converted into residential apartments or other industrial economic spaces. These secondary users refurbish the original structures to accommodate their new specialised requirements and this mostly happens after the buildings have been lying vacant for a long period of time. The study by Y.Long et al. (2011) narrates the changes in land use, identification of driving forces and the mapping of areas that are experiencing intense land use transformation. Properties that were developed for a focused particular use, were found to have been redeveloped within a few years for other functions. Subjects that were included in the sample were selected to meet specific criteria. The stakeholders had to meet the following criteria to be included in the sample: They were registered professionals in the built environment such as: Architecture, Engineering (civil, electrical, mechanical and structural), Quantity Surveying, Town Planning, Construction Management and Estate management The method that was used to collect data was self-completion questionnaire that was given out by electronic mail. After the data was collected, it was organised and analysed. For the analysis of closed-ended questions, an online programme called QuestionPro, was used, data was analysed by using descriptive statistics and frequency tables were drawn and from these, the data was presented in pie diagrams and bar graphs. While it is necessary to expand the horizons of the ever-growing global population, it is imperative that all stakeholders in the building industry work together to find sustainable solutions to residential and industrial development.
- Full Text:
- Date Issued: 2020
- Authors: Kuliti, Gerald
- Date: 2020
- Subjects: Commercial buildings -- South Africa , Buildings -- Conservation and restoration Buildings -- Maintenance and repair
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46075 , vital:39485
- Description: In the major cities of South Africa, there is a prevalence of originally built commercial buildings that are being converted into residential apartments or other industrial economic spaces. These secondary users refurbish the original structures to accommodate their new specialised requirements and this mostly happens after the buildings have been lying vacant for a long period of time. The study by Y.Long et al. (2011) narrates the changes in land use, identification of driving forces and the mapping of areas that are experiencing intense land use transformation. Properties that were developed for a focused particular use, were found to have been redeveloped within a few years for other functions. Subjects that were included in the sample were selected to meet specific criteria. The stakeholders had to meet the following criteria to be included in the sample: They were registered professionals in the built environment such as: Architecture, Engineering (civil, electrical, mechanical and structural), Quantity Surveying, Town Planning, Construction Management and Estate management The method that was used to collect data was self-completion questionnaire that was given out by electronic mail. After the data was collected, it was organised and analysed. For the analysis of closed-ended questions, an online programme called QuestionPro, was used, data was analysed by using descriptive statistics and frequency tables were drawn and from these, the data was presented in pie diagrams and bar graphs. While it is necessary to expand the horizons of the ever-growing global population, it is imperative that all stakeholders in the building industry work together to find sustainable solutions to residential and industrial development.
- Full Text:
- Date Issued: 2020
Gender, rock and the electrical guitar : A post -structural reading
- Fourie, Jeandre, Potgieter, Zelda
- Authors: Fourie, Jeandre , Potgieter, Zelda
- Date: 2020
- Subjects: Rock Music -- History -- Criticism , Gender identity in Music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: http://hdl.handle.net/10948/46880 , vital:39721
- Description: Rock ‘n’ roll and, by extension, the electric guitar, is widely considered as a “gendered field of practice” (Leonard 2015: 184), governed by the hyper-masculine ideal (Hartman and Schmid 2014: 60). Both function as extensions of masculinity, representing an ideological binary of male superiority and female inferiority. This manifests concretely in the perceived disparity regarding gender representation amongst rock musicians, particularly guitarists, and often leads to somewhat one-dimensional views about the misogyny associated with the genre (Gracyk 2001: 182-183). However, by applying a post-structural reading and deconstructing the binary according to a theoretical framework inspired by the works of Julia Kristeva -- presented in a Hegelian dialectical model, with additional insight drawn from the works of Jacques Lacan and Sigmund Freud- it becomes apparent that the male claim to, and overrepresentation within,the genre is a multifaceted issue, born of a combination of natural and social constructionist factors.
- Full Text:
- Date Issued: 2020
- Authors: Fourie, Jeandre , Potgieter, Zelda
- Date: 2020
- Subjects: Rock Music -- History -- Criticism , Gender identity in Music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: http://hdl.handle.net/10948/46880 , vital:39721
- Description: Rock ‘n’ roll and, by extension, the electric guitar, is widely considered as a “gendered field of practice” (Leonard 2015: 184), governed by the hyper-masculine ideal (Hartman and Schmid 2014: 60). Both function as extensions of masculinity, representing an ideological binary of male superiority and female inferiority. This manifests concretely in the perceived disparity regarding gender representation amongst rock musicians, particularly guitarists, and often leads to somewhat one-dimensional views about the misogyny associated with the genre (Gracyk 2001: 182-183). However, by applying a post-structural reading and deconstructing the binary according to a theoretical framework inspired by the works of Julia Kristeva -- presented in a Hegelian dialectical model, with additional insight drawn from the works of Jacques Lacan and Sigmund Freud- it becomes apparent that the male claim to, and overrepresentation within,the genre is a multifaceted issue, born of a combination of natural and social constructionist factors.
- Full Text:
- Date Issued: 2020
Genetic connectivity in sandy beach macroinfauna with contrasting life histories and zonation patterns
- Authors: Bezuidenhout, Karien
- Date: 2020
- Subjects: Fishes -- Genetics , Seashore ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/45944 , vital:39380
- Description: Open-ocean sandy beaches are highly dynamic ecosystems that continuously respond to waves, tides and storms. These beaches support a suite of uniquely adapted fauna that exhibits a high degree of endemism. This diversity, which also includes some economically important resource species, contributes to the great socio-economic and ecological value of sandy beach systems, which provide ecosystem services such as nutrient recycling and water purification, fish nursery habitat (surf zone), and natural buffering against storms. Despite their broad global distribution comprising ~70 % of the world’s ice-free coastline, beaches are naturally fragmented by other intertidal marine habitats and extensive coastal development. Sea-level rise is now threatening beaches, particularly along developed coasts through coastal squeeze, with an increased risk of habitat loss and exacerbated fragmentation. Such habitat loss has important implications for population and species persistence, depending on the level of connectivity among populations. While sandy beach macroinfauna tend to be highly mobile across and along shore, they also show a strong bias towards direct, or aplanktonic, development; the latter could reduce opportunities for dispersal and sustained population connectivity. However, comparatively little is known about population connectivity on sandy beaches, limiting scientifically sound management of much of the world’s coastline. This study aims to address this knowledge gap by working towards a conceptual model quantifying population connectivity, and by investigating the specific roles of life history, across-shore zonation, and geographic range as putative indicators and possibly drivers of genetic differentiation (ΦST) and connectivity (gene flow) among beach macroinvertebrate populations. The main hypotheses are that 1) species with a pelagic larval stage will display lower genetic differentiation with higher rates of gene flow among populations than species with a benthic lecithotrophic larval stage or direct development; and 2) genetic differentiation among populations will decrease along an across-shore axis, from the supratidal to the low water mark. Two opposing hypotheses were tested concerning the relationship between genetic structure and distributional range: 3a) Species with a large range (measured as distance and number of latitudes) will show less genetic differentiation than those with a narrow range, because they are more able to disperse; or 3b) more widely distributed species may occur across more phylogenetic | v breaks, and thus show higher genetic differentiation than species restricted to a smaller ranges and single biogeographic provinces. First, the extent and likely drivers of population connectivity were investigated for a suite of temperate South African macroinfauna. Very low, non-significant genetic differentiation was demonstrated for the beach clam Donax serra, thus supporting the hypothesis that pelagic larval dispersers display low/no genetic differentiation among populations (Chapter 2). Statistical power of the COI locus was, however, low in this species, due to reduced genetic variability which could be attributed to an expansion from a small source population into extant habitats. The results highlighted the need for caution when interpreting a lack of genetic differentiation as evidence for population connectivity. Nevertheless, COI sequences verified that D. serra occupying the cool and warm-temperate regions of the South African coast, constitute a single species, despite morphological and behavioural differences between inhabitants of these two bioregions. D. sordidus, a congener of D. serra, and endemic to the warm-temperate (Agulhas) bioregion of South Africa, was investigated to test two opposing hypotheses (Chapter 3): 1) this pelagic larval disperser lack genetic differentiation with high rates of gene flow across its range, or alternatively 2) these clams are genetically structured across their range due to the influence of freshwater input (measured as distance to nearest estuary), and morphodynamics of the surf zone (represented by surf-zone width). Significant global ΦST was estimated for D. sordidus, with differentiation predominantly driven by haplotype frequencies at a single study site and estimates of gene flow among most sample locations generally high. Tentative evidence suggested that natural selection driven by differences in water salinity due to estuarine runoff and surf-zone width, might be maintaining two dominant haplotypes across the range of this species. Beach clams from the Southern Hemisphere, occupying different distributional ranges, were compared to test the hypothesis that genetic structure decreases with an increase in range. This hypothesis was poorly supported by the results; opposite (yet mostly non-significant) trends demonstrated for ΦST and haplotype diversity, thus providing some support for the alternative hypothesis that more phylogeographic breaks in broad-ranging species results in higher estimates of genetic structure in these species.
- Full Text:
- Date Issued: 2020
- Authors: Bezuidenhout, Karien
- Date: 2020
- Subjects: Fishes -- Genetics , Seashore ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/45944 , vital:39380
- Description: Open-ocean sandy beaches are highly dynamic ecosystems that continuously respond to waves, tides and storms. These beaches support a suite of uniquely adapted fauna that exhibits a high degree of endemism. This diversity, which also includes some economically important resource species, contributes to the great socio-economic and ecological value of sandy beach systems, which provide ecosystem services such as nutrient recycling and water purification, fish nursery habitat (surf zone), and natural buffering against storms. Despite their broad global distribution comprising ~70 % of the world’s ice-free coastline, beaches are naturally fragmented by other intertidal marine habitats and extensive coastal development. Sea-level rise is now threatening beaches, particularly along developed coasts through coastal squeeze, with an increased risk of habitat loss and exacerbated fragmentation. Such habitat loss has important implications for population and species persistence, depending on the level of connectivity among populations. While sandy beach macroinfauna tend to be highly mobile across and along shore, they also show a strong bias towards direct, or aplanktonic, development; the latter could reduce opportunities for dispersal and sustained population connectivity. However, comparatively little is known about population connectivity on sandy beaches, limiting scientifically sound management of much of the world’s coastline. This study aims to address this knowledge gap by working towards a conceptual model quantifying population connectivity, and by investigating the specific roles of life history, across-shore zonation, and geographic range as putative indicators and possibly drivers of genetic differentiation (ΦST) and connectivity (gene flow) among beach macroinvertebrate populations. The main hypotheses are that 1) species with a pelagic larval stage will display lower genetic differentiation with higher rates of gene flow among populations than species with a benthic lecithotrophic larval stage or direct development; and 2) genetic differentiation among populations will decrease along an across-shore axis, from the supratidal to the low water mark. Two opposing hypotheses were tested concerning the relationship between genetic structure and distributional range: 3a) Species with a large range (measured as distance and number of latitudes) will show less genetic differentiation than those with a narrow range, because they are more able to disperse; or 3b) more widely distributed species may occur across more phylogenetic | v breaks, and thus show higher genetic differentiation than species restricted to a smaller ranges and single biogeographic provinces. First, the extent and likely drivers of population connectivity were investigated for a suite of temperate South African macroinfauna. Very low, non-significant genetic differentiation was demonstrated for the beach clam Donax serra, thus supporting the hypothesis that pelagic larval dispersers display low/no genetic differentiation among populations (Chapter 2). Statistical power of the COI locus was, however, low in this species, due to reduced genetic variability which could be attributed to an expansion from a small source population into extant habitats. The results highlighted the need for caution when interpreting a lack of genetic differentiation as evidence for population connectivity. Nevertheless, COI sequences verified that D. serra occupying the cool and warm-temperate regions of the South African coast, constitute a single species, despite morphological and behavioural differences between inhabitants of these two bioregions. D. sordidus, a congener of D. serra, and endemic to the warm-temperate (Agulhas) bioregion of South Africa, was investigated to test two opposing hypotheses (Chapter 3): 1) this pelagic larval disperser lack genetic differentiation with high rates of gene flow across its range, or alternatively 2) these clams are genetically structured across their range due to the influence of freshwater input (measured as distance to nearest estuary), and morphodynamics of the surf zone (represented by surf-zone width). Significant global ΦST was estimated for D. sordidus, with differentiation predominantly driven by haplotype frequencies at a single study site and estimates of gene flow among most sample locations generally high. Tentative evidence suggested that natural selection driven by differences in water salinity due to estuarine runoff and surf-zone width, might be maintaining two dominant haplotypes across the range of this species. Beach clams from the Southern Hemisphere, occupying different distributional ranges, were compared to test the hypothesis that genetic structure decreases with an increase in range. This hypothesis was poorly supported by the results; opposite (yet mostly non-significant) trends demonstrated for ΦST and haplotype diversity, thus providing some support for the alternative hypothesis that more phylogeographic breaks in broad-ranging species results in higher estimates of genetic structure in these species.
- Full Text:
- Date Issued: 2020
Gentrification in the Nelson Mandela Bay central business district
- Mageda, Nomthandazo Christellene
- Authors: Mageda, Nomthandazo Christellene
- Date: 2020
- Subjects: Gentrification , Urban renewal-- South Africa -- Nelson Mandela Metropolitan Municipality Neighborhoods -- South Africa -- Nelson Mandela Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46119 , vital:39498
- Description: Gentrification is the process by which middle-class residents settle inner city neighborhood previously occupied by working-class. Gentrification has long been viewed as a consumption phenomenon, which is triggered by the urge of a certain fraction of a middle class – gentrifies – to create and maintain distinction. The research is designed as a socio-economic account to discuss the development in the NMB CBD area. In my research I examine the multiscalar forces affecting neighborhood change. This study will also examine the elements affecting and also the benefits of the gentrification process using quantitative methods. The CBD of the NMB represents certain universalities of gentrification in an old city. Today the city is no longer the regular of development but instead its progenitor. Adopting the language of “urbanization” and “cities of the future” will be considered in gearing the economic development arm. It does so by an extensive mapping of gentrification processes in Port Elizabeth. It also contains a smaller study on gentrification in Cape Town and also on an international level. The outcomes provide telling insights into gentrification as a generic process affecting not just low income areas (classical gentrification) and high income areas (super-gentrification), but also a wide-ranging spectrum of medium-income areas (ordinary gentrification). This study examines the interdependent variables of gentrification, going beyond a profitable analysis and incorporating the voice of all the actors involved in the process of gentrification, using quantitative analysis. By taking into account all perspectives, this study permits a holistic understanding of the social costs and benefits associated with gentrification. As multifaceted as gentrification is, it is becoming more pervasive in cities globally, a holistic tally of the social costs and benefits of revitalization projects becoming imperative. The study concludes with discussions of the contributions, limitations, recommendations for the NMB CBD and other cities that are considering revitalizing their urban cores and implications for future research.
- Full Text:
- Date Issued: 2020
- Authors: Mageda, Nomthandazo Christellene
- Date: 2020
- Subjects: Gentrification , Urban renewal-- South Africa -- Nelson Mandela Metropolitan Municipality Neighborhoods -- South Africa -- Nelson Mandela Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46119 , vital:39498
- Description: Gentrification is the process by which middle-class residents settle inner city neighborhood previously occupied by working-class. Gentrification has long been viewed as a consumption phenomenon, which is triggered by the urge of a certain fraction of a middle class – gentrifies – to create and maintain distinction. The research is designed as a socio-economic account to discuss the development in the NMB CBD area. In my research I examine the multiscalar forces affecting neighborhood change. This study will also examine the elements affecting and also the benefits of the gentrification process using quantitative methods. The CBD of the NMB represents certain universalities of gentrification in an old city. Today the city is no longer the regular of development but instead its progenitor. Adopting the language of “urbanization” and “cities of the future” will be considered in gearing the economic development arm. It does so by an extensive mapping of gentrification processes in Port Elizabeth. It also contains a smaller study on gentrification in Cape Town and also on an international level. The outcomes provide telling insights into gentrification as a generic process affecting not just low income areas (classical gentrification) and high income areas (super-gentrification), but also a wide-ranging spectrum of medium-income areas (ordinary gentrification). This study examines the interdependent variables of gentrification, going beyond a profitable analysis and incorporating the voice of all the actors involved in the process of gentrification, using quantitative analysis. By taking into account all perspectives, this study permits a holistic understanding of the social costs and benefits associated with gentrification. As multifaceted as gentrification is, it is becoming more pervasive in cities globally, a holistic tally of the social costs and benefits of revitalization projects becoming imperative. The study concludes with discussions of the contributions, limitations, recommendations for the NMB CBD and other cities that are considering revitalizing their urban cores and implications for future research.
- Full Text:
- Date Issued: 2020
Grandmothers’ perceptions regarding breastfeeding following training for breastfeeding support in Nelson Mandela Bay Health District: a qualitative study
- Authors: Manyange, Rumbidzai Lynda
- Date: 2020
- Subjects: Breastfeeding promotion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46441 , vital:39583
- Description: Rationale: Although there has been active promotion of breastfeeding for the past decades in South Africa, there has been inadequate support from multiple role players. Strategies that do not engage important family members, such as grandmothers in supporting breastfeeding are likely to fail. In many African countries, grandmothers often make critical decisions about early child feeding practices, particularly for first-time mothers. Despite the influence grandmothers have, limited studies have been done in South Africa to assess whether it is possible to change breastfeeding outcomes by empowering grandmothers as well as including them in intervention programmes. Nelson Mandela University, in collaboration with the United Nations Children Education Fund (UNICEF) and a local Non-Governmental Organisation (NGO), recently launched a breastfeeding support programme, Sakha Esethu. The aim was to capacitate both primary and secondary caregivers to enable them to provide optimal breastfeeding support for mothers in various communities. However, it was important to explore the perceptions of grandmothers regarding breastfeeding to assess whether improved breastfeeding knowledge will translate into changed perceptions and therefore improved support for exclusive breastfeeding in communities in Nelson Mandela Bay. Aim: The study aimed to describe and explore the perceptions of grandmothers regarding breastfeeding after participating in a breastfeeding support programme in Nelson Mandela Bay health district (NMBHD). Methodology: The study followed a descriptive-exploratory, contextual study design with a qualitative approach. The four ethical principles that guided the study were: autonomy, non-maleficence, beneficence and justice. The researcher conducted five focus group discussions (FGD) at ECD centres in NMBHD, where 34 grandmothers participated in the study. Participants were chosen using a purposively sampling technique and data was collected using FGD interviews. Verbatim transcription was done after every FGD and data was analysed using the eight steps of Tesch’s analysis technique. An independent coder with experience in qualitative data analysis assisted to verify the codes generated. vi Results: Four major themes and eleven subthemes emerged through data analysis. The identified themes were: (1)Participant knowledge regarding breastfeeding. Participants reflected on poor knowledge on the perceived maternal benefits of breastfeeding, variance on the optimal duration of breastfeeding and recognised myths and cultural taboos related to breastfeeding, such as the use of traditional mixes, “dirty” breastmilk and perceived milk insufficiency; (2) Views on complementary feeding. The subthemes that emerged included: Participants shared their views on the age of introduction for complementary foods and feeding practices for infants; (3) Challenges related to breastfeeding. The challenges identified included: challenges for working mothers and those attending school, lack of family support and societal support for EBF, lack of support from healthcare professionals relating to initiation and continuation of breastfeeding and difficulties coping with breast health. (4) Participants enthused about the impact of being supported to optimise breastfeeding.Participants were able to share on the camaraderie benefits experienced from the Sakha Esethu group as well as on the support grandmothers can provide. Conclusion and Recommendations: This study confirmed that participation of grandmothers in the Sakha Esethu programme had an impact on changes in grandmothers’ perceptions regarding breastfeeding. However, the programme can be further improved by placing more emphasis on aspects i.e. maternal benefits of breastfeeding, during mentor training. Furthermore, there is a need to strengthen healthcare worker support and training, especially with regards to adapting counselling strategies to include breastfeeding challenges and cultural beliefs.
- Full Text:
- Date Issued: 2020
- Authors: Manyange, Rumbidzai Lynda
- Date: 2020
- Subjects: Breastfeeding promotion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46441 , vital:39583
- Description: Rationale: Although there has been active promotion of breastfeeding for the past decades in South Africa, there has been inadequate support from multiple role players. Strategies that do not engage important family members, such as grandmothers in supporting breastfeeding are likely to fail. In many African countries, grandmothers often make critical decisions about early child feeding practices, particularly for first-time mothers. Despite the influence grandmothers have, limited studies have been done in South Africa to assess whether it is possible to change breastfeeding outcomes by empowering grandmothers as well as including them in intervention programmes. Nelson Mandela University, in collaboration with the United Nations Children Education Fund (UNICEF) and a local Non-Governmental Organisation (NGO), recently launched a breastfeeding support programme, Sakha Esethu. The aim was to capacitate both primary and secondary caregivers to enable them to provide optimal breastfeeding support for mothers in various communities. However, it was important to explore the perceptions of grandmothers regarding breastfeeding to assess whether improved breastfeeding knowledge will translate into changed perceptions and therefore improved support for exclusive breastfeeding in communities in Nelson Mandela Bay. Aim: The study aimed to describe and explore the perceptions of grandmothers regarding breastfeeding after participating in a breastfeeding support programme in Nelson Mandela Bay health district (NMBHD). Methodology: The study followed a descriptive-exploratory, contextual study design with a qualitative approach. The four ethical principles that guided the study were: autonomy, non-maleficence, beneficence and justice. The researcher conducted five focus group discussions (FGD) at ECD centres in NMBHD, where 34 grandmothers participated in the study. Participants were chosen using a purposively sampling technique and data was collected using FGD interviews. Verbatim transcription was done after every FGD and data was analysed using the eight steps of Tesch’s analysis technique. An independent coder with experience in qualitative data analysis assisted to verify the codes generated. vi Results: Four major themes and eleven subthemes emerged through data analysis. The identified themes were: (1)Participant knowledge regarding breastfeeding. Participants reflected on poor knowledge on the perceived maternal benefits of breastfeeding, variance on the optimal duration of breastfeeding and recognised myths and cultural taboos related to breastfeeding, such as the use of traditional mixes, “dirty” breastmilk and perceived milk insufficiency; (2) Views on complementary feeding. The subthemes that emerged included: Participants shared their views on the age of introduction for complementary foods and feeding practices for infants; (3) Challenges related to breastfeeding. The challenges identified included: challenges for working mothers and those attending school, lack of family support and societal support for EBF, lack of support from healthcare professionals relating to initiation and continuation of breastfeeding and difficulties coping with breast health. (4) Participants enthused about the impact of being supported to optimise breastfeeding.Participants were able to share on the camaraderie benefits experienced from the Sakha Esethu group as well as on the support grandmothers can provide. Conclusion and Recommendations: This study confirmed that participation of grandmothers in the Sakha Esethu programme had an impact on changes in grandmothers’ perceptions regarding breastfeeding. However, the programme can be further improved by placing more emphasis on aspects i.e. maternal benefits of breastfeeding, during mentor training. Furthermore, there is a need to strengthen healthcare worker support and training, especially with regards to adapting counselling strategies to include breastfeeding challenges and cultural beliefs.
- Full Text:
- Date Issued: 2020
Guidelines for the use of machine learning to predict student project group academic performance
- Authors: Evezard, Ryan
- Date: 2020
- Subjects: Academic achievement , Machine learning
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/46042 , vital:39476
- Description: Education plays a crucial role in the growth and development of a country. However, in South Africa, there is a limited capacity and an increasing demand of students seeking an education. In an attempt to address this demand, universities are pressured into accepting more students to increase their throughput. This pressure leads to educators having less time to give students individual attention. This study aims to address this problem by demonstrating how machine learning can be used to predict student group academic performance so that educators may allocate more resources and attention to students and groups at risk. The study focused on data obtained from the third-year capstone project for the diploma in Information Technology at the Nelson Mandela University. Learning analytics and educational data mining and their processes were discussed with an in-depth look at the machine learning techniques involved therein. Artificial neural networks, decision trees and naïve Bayes classifiers were proposed and motivated for prediction modelling. An experiment was performed resulting in proposed guidelines, which give insight and recommendations for the use of machine learning to predict student group academic performance.
- Full Text:
- Date Issued: 2020
- Authors: Evezard, Ryan
- Date: 2020
- Subjects: Academic achievement , Machine learning
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/46042 , vital:39476
- Description: Education plays a crucial role in the growth and development of a country. However, in South Africa, there is a limited capacity and an increasing demand of students seeking an education. In an attempt to address this demand, universities are pressured into accepting more students to increase their throughput. This pressure leads to educators having less time to give students individual attention. This study aims to address this problem by demonstrating how machine learning can be used to predict student group academic performance so that educators may allocate more resources and attention to students and groups at risk. The study focused on data obtained from the third-year capstone project for the diploma in Information Technology at the Nelson Mandela University. Learning analytics and educational data mining and their processes were discussed with an in-depth look at the machine learning techniques involved therein. Artificial neural networks, decision trees and naïve Bayes classifiers were proposed and motivated for prediction modelling. An experiment was performed resulting in proposed guidelines, which give insight and recommendations for the use of machine learning to predict student group academic performance.
- Full Text:
- Date Issued: 2020
High-intensity Interval Training utilising a standardised versus customised training programme among endurance trained male cyclists
- Authors: Salzwedel, Jarred Wayne
- Date: 2020
- Subjects: Cycling South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46423 , vital:39596
- Description: The primary aim of this study was to compare the effect of a standardised versus customised high-intensity interval training programmeon performance indicators of endurance trained male cyclists utilising a standardised method of prescribing intervals in comparison to a customised method of prescribing intervals based on training feedback. The study was exploratory and quasi-experimental in nature and utilized a quantitative approach. A quasi-experimental, pretest-postestcontrol group study design was used. A total number of 22 participants that met the inclusion criteria were included in the study by means of purposive sampling. The participants were subdivided into an experimental group (n=11) and a control group (n=11)by means of random stratification in order to ensure performance equality between the two groups. The experimental group completed a High-Intensity Interval Training (HIIT) block of 28 days (four weeks) with three weeks of interval-based sessions and one recovery week ending off the block. The programmeutilised the same “anaerobic” type intervals (10 x 30 seconds at 170% PPO with 4 minutes 30 seconds recovery) as the control group, performed twice per week for three consecutive weeks. The Lamberts and Lambert submaximal cycling test (LSCT) was used to determine whether a participant in the experimental group could start his HIIT session on a particular day.Participants were notallowed to start their HIIT session if twoor more of the set criteria weremet.If the participants did not qualify to participate in a HIIT session they were required to perform a low intensity training session in the same venue. Differences between the pre-and post-test showed statistically non-significant improvements (p>0.05) from pre-to post-test for both the experimental and control groups in respect of the physiological variables measured (gas exchange threshold, respiratory compensation point, maximal oxygen consumption). The experimental group did however show more positive, but statistically non-significantimprovements in peak power output. The findings of this study therefore showed that no significant within group nor between group improvements were achieved utilizing a standised versus customised HIIT training programme over the four-week study period. The findings do however suggest that the LSCT may have merit in prescribing HIIT sessions in trained athletesas suggested by the improvements of the experimental group’s peak power output.
- Full Text:
- Date Issued: 2020
- Authors: Salzwedel, Jarred Wayne
- Date: 2020
- Subjects: Cycling South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46423 , vital:39596
- Description: The primary aim of this study was to compare the effect of a standardised versus customised high-intensity interval training programmeon performance indicators of endurance trained male cyclists utilising a standardised method of prescribing intervals in comparison to a customised method of prescribing intervals based on training feedback. The study was exploratory and quasi-experimental in nature and utilized a quantitative approach. A quasi-experimental, pretest-postestcontrol group study design was used. A total number of 22 participants that met the inclusion criteria were included in the study by means of purposive sampling. The participants were subdivided into an experimental group (n=11) and a control group (n=11)by means of random stratification in order to ensure performance equality between the two groups. The experimental group completed a High-Intensity Interval Training (HIIT) block of 28 days (four weeks) with three weeks of interval-based sessions and one recovery week ending off the block. The programmeutilised the same “anaerobic” type intervals (10 x 30 seconds at 170% PPO with 4 minutes 30 seconds recovery) as the control group, performed twice per week for three consecutive weeks. The Lamberts and Lambert submaximal cycling test (LSCT) was used to determine whether a participant in the experimental group could start his HIIT session on a particular day.Participants were notallowed to start their HIIT session if twoor more of the set criteria weremet.If the participants did not qualify to participate in a HIIT session they were required to perform a low intensity training session in the same venue. Differences between the pre-and post-test showed statistically non-significant improvements (p>0.05) from pre-to post-test for both the experimental and control groups in respect of the physiological variables measured (gas exchange threshold, respiratory compensation point, maximal oxygen consumption). The experimental group did however show more positive, but statistically non-significantimprovements in peak power output. The findings of this study therefore showed that no significant within group nor between group improvements were achieved utilizing a standised versus customised HIIT training programme over the four-week study period. The findings do however suggest that the LSCT may have merit in prescribing HIIT sessions in trained athletesas suggested by the improvements of the experimental group’s peak power output.
- Full Text:
- Date Issued: 2020
Hydrogeochemistry of shallow karoo basin aquifers in the border-kei region flanking the Indian Ocean, Eastern Cape, South Africa
- Authors: Jeppesen, Keegan
- Date: 2020
- Subjects: Water chemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48401 , vital:40856
- Description: As the potential for shale gas exploitation becomes a real possibility across parts of the Karoo in South Africa, and groundwater is one of the systems that could become heavily stressed if the shale gas industry becomes operational, it is important therefore to gain a better understanding into the hydrogeochemical systems and processes that occur within the Karoo Basin. Groundwater systems are very complex and are heavily relied upon in many areas across the Karoo that are surface water deficient. Groundwater is used domestically, for irrigation and livestock as well as in industry. A hydrogeochemical baseline investigation was undertaken in the shallow Karoo Basin aquifers (< 100 m) of the Border-Kei region with in the Eastern Cape of South Africa, which flanks the Indian Ocean. Since it has been suggested that seawater might be used as a potential fracking fluid, it is important to also establish baseline data linked to potential seawater salinisation in the coastal aquifers. This was achieved by sampling water from both 35 production and 3 non-production boreholes (by making use of a bailer and discrete interval sampler). Water from all 38 samples was analysed for major anions and cations, trace elements as well as for δ 18O and δ 2H stable isotopes. Results indicate that the majority of the groundwater in the study area falls within acceptable limits for domestic use, and although slightly saline, is exploitable for other uses as well. It was also found that dolerite dykes that have intruded into the Karoo Basin sediments have slight effects on the groundwater chemistry, but that these effects are also masked by the water-rock interactions occurring with the aquifer. It was also determined with major ions and stable isotopes that although the coastal aquifers do have saline signatures (EC > 200 mS/m) this is not due to salinisation via seawater intrusion. It is instead postulated that the salinity arises from marine aerosols that have introduced NaCl onto the soil layer, and which then leaches into the groundwater system through precipitation or irrigation. In the event of shale gas extraction through fracking or the expansion of rural and urban centres, this project serves as a preliminary hydrogeochemical baseline before any of these processes proceed within the Karoo Basin.
- Full Text:
- Date Issued: 2020
- Authors: Jeppesen, Keegan
- Date: 2020
- Subjects: Water chemistry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48401 , vital:40856
- Description: As the potential for shale gas exploitation becomes a real possibility across parts of the Karoo in South Africa, and groundwater is one of the systems that could become heavily stressed if the shale gas industry becomes operational, it is important therefore to gain a better understanding into the hydrogeochemical systems and processes that occur within the Karoo Basin. Groundwater systems are very complex and are heavily relied upon in many areas across the Karoo that are surface water deficient. Groundwater is used domestically, for irrigation and livestock as well as in industry. A hydrogeochemical baseline investigation was undertaken in the shallow Karoo Basin aquifers (< 100 m) of the Border-Kei region with in the Eastern Cape of South Africa, which flanks the Indian Ocean. Since it has been suggested that seawater might be used as a potential fracking fluid, it is important to also establish baseline data linked to potential seawater salinisation in the coastal aquifers. This was achieved by sampling water from both 35 production and 3 non-production boreholes (by making use of a bailer and discrete interval sampler). Water from all 38 samples was analysed for major anions and cations, trace elements as well as for δ 18O and δ 2H stable isotopes. Results indicate that the majority of the groundwater in the study area falls within acceptable limits for domestic use, and although slightly saline, is exploitable for other uses as well. It was also found that dolerite dykes that have intruded into the Karoo Basin sediments have slight effects on the groundwater chemistry, but that these effects are also masked by the water-rock interactions occurring with the aquifer. It was also determined with major ions and stable isotopes that although the coastal aquifers do have saline signatures (EC > 200 mS/m) this is not due to salinisation via seawater intrusion. It is instead postulated that the salinity arises from marine aerosols that have introduced NaCl onto the soil layer, and which then leaches into the groundwater system through precipitation or irrigation. In the event of shale gas extraction through fracking or the expansion of rural and urban centres, this project serves as a preliminary hydrogeochemical baseline before any of these processes proceed within the Karoo Basin.
- Full Text:
- Date Issued: 2020
Ichthyofaunal and isotope changes along the rivere-stuarine continuum in a fluvially dominated Southern African coastal system
- Authors: Nashima, Festus Panduleni
- Date: 2020
- Subjects: Fishes -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48555 , vital:40890
- Description: Catchment to coast and the continuum concept recognize linkages and make it imperative to take an ecosystem approach to catchment management, water allocation, fisheries management and environmental management as a whole. Fishes that utilise estuarine environments are influenced by physical and chemical conditions as well as biological interactions. Community structure, drivers and trophic linkages between species of different origin, utilising the low salinity waters along the riverestuarine continuum remain poorly understood in the lower Orange River and estuary. This body of work investigated the spatio-temporal dynamics structuring fishes in the lower Orange River Estuary Continuum (OREC) within the context of River Continuum (Vannote et al., 1980). Eight years (2004 - 2018) of seasonal sampling at 18 sites comprised of multi-species catches were analysed, including three years (2016 - 2018) exploring trophic linkages between the dominant species of marine, estuarine and freshwater fishes in the system. In total, 30 species belonging to 16 families were collected in the lower OREC. The Family Mugilidae dominated all catches. Fish species composition was comprised mostly of freshwater (47%), followed by the marine (33%) and estuarine species (20%). Numerically, the marine euryhaline Chelon richardsonii and solely estuarine Gilchristella aestuaria were the dominant species in the estuary region (site 1 - 11) with 95% and 4% contribution, respectively. Chelon richardsonii also dominated all catches (67%) upstream into the river (site 12 - 18), followed by freshwater Labeobarbus aeneus (13%) and Pseudocrenilabrus philander (8%). This highlights the point that besides the marine Chelon richardsonii, other species albeit marine, estuarine and freshwater are utilising unique areas within the OREC. Temporal differentiation in fish abundance (catch-per-unit-effort, CPUE), diversity, richness and evenness were higher in the high-flow season than the low-flow season. Mean CPUE was higher at the mouth of the estuary and declined upstream into the river, whilst species diversity (including richness and evenness) increased upstream. High catches but low species diversity observed close to the mouth of the estuary were attributed to the domination of Chelon richardsonii. However, species diversity increased upstream in the river due to the dominance of freshwater fishes coupled with several marine and estuarine species. This diversity patterns were inconsistent with the general Remane and revised model for estuaries, hence a new RiverEstuarine Continuum concept suitable for OREC was developed. With the exception of Chelon richardsonii, spatial variability in the length-frequency distribution of most fishes was observed. Physico-chemical drivers provided valuable information on adaptation limits of species movement and distribution. Fishes were structured along a salinity gradient and interaction between temperature and salinity influenced community structure and diversity patterns in the OREC. Fish species utilising the lower OREC are predominantly zoobenthivores but a few detritivores/planktivores dominate numerically. Trophic inferences from stable isotope analysis showed increased carbon isotope values (δ 13C) with salinity toward the mouth of the estuary, whilst nitrogen isotope values (δ 15N) increased upstream into the river. Ontogenetic shifts in the SI ratios of all five fish species (marine Chelon richardsonii; estuarine Gilchristella aestuaria; freshwater Labeobarbus aeneus, Pseudocrenilabrus philander and Mesobola brevianalis) were observed in the OREC. Variability in seasons and salinity gradient influenced the SI ratios of several fish species. Seasonal changes influenced the δ 13C ratios of all species, except for Labeobarbus aeneus and Pseudocrenilabrus philander whereas the δ 15N ratios of all species (except for Mesobola brevianalis) differed significantly between the high-flow and low-flow season. This can be due to their feeding on specific life-history stages, such as eggs, larvae, gametophytes, sporophytes or zoospores of prey. Stable isotope ratios revealed that Mesobola brevianalis fed at a higher trophic level than Chelon richardsonii and Gilchristella aestuaria. Mesobola brevianalis feed on planktonic crustacean and insects. Chelon richardsonii feed on a wide range of prey, with prey switching between planktonic and detritivore food resources, whilst Gilchristella aestuaria feed selectively on zooplankton but switched to filter feeding modes in turbid water. Generally, δ 15N SI ratios increase with growth, however, for Labeobarbus aeneus, it was significantly higher in small size length than in large size individuals, probably because most of the juveniles assessed were caught upstream where δ 15N increases. Juveniles of Labeobarbus aeneus mainly feed on zoobenthos whilst in larger fish phytoplankton becomes increasingly important, suggesting the possibility that zoobenthos was more 15N enriched than plant materials. The trophic niches of Mesobola brevianalis were isotopically distinguishable from Chelon richardsonii and Gilchristella aestuaria during the low-flow season, revealing that these species are probably accessing carbon sources from different food chains. During high-flow season, the isotopic niche overlapped among several species, indicating that these species are probably deriving carbon sources from the same or similar food chains. Results from Layman isotope-based metrics revealed that Chelon richardsonii, Pseudocrenilabrus philander and Labeobarbus aeneus occupied the widest isotopic niche in the lower OREC, suggesting that these species are utilising food sources which may be derived from a wide variety of carbon sources. Mesobola brevianalis had the narrowest isotopic niche, however this does not imply "a narrow range of food sources’’ for the species. Overall, the potential carbon sources for selected fish species revealed that they are supported by a variety of food sources (mainly phyto-and zooplanktonic) or their food items constituted different basal sources which enable them to coexist. This study represents the first, integrated investigation of trophic relations among fishes of different origin using δ 13C and δ15N SI analyses. The current study provides a broader understanding of fish ecology within the River-Estuarine Continuum in the lower Orange River and estuary. By filling research gaps identified in the lower OREC, this synthesis of work also supports and informs management, conservation and responsible utilisation of estuarine fishery resources, in particular within the OREC.
- Full Text:
- Date Issued: 2020
- Authors: Nashima, Festus Panduleni
- Date: 2020
- Subjects: Fishes -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48555 , vital:40890
- Description: Catchment to coast and the continuum concept recognize linkages and make it imperative to take an ecosystem approach to catchment management, water allocation, fisheries management and environmental management as a whole. Fishes that utilise estuarine environments are influenced by physical and chemical conditions as well as biological interactions. Community structure, drivers and trophic linkages between species of different origin, utilising the low salinity waters along the riverestuarine continuum remain poorly understood in the lower Orange River and estuary. This body of work investigated the spatio-temporal dynamics structuring fishes in the lower Orange River Estuary Continuum (OREC) within the context of River Continuum (Vannote et al., 1980). Eight years (2004 - 2018) of seasonal sampling at 18 sites comprised of multi-species catches were analysed, including three years (2016 - 2018) exploring trophic linkages between the dominant species of marine, estuarine and freshwater fishes in the system. In total, 30 species belonging to 16 families were collected in the lower OREC. The Family Mugilidae dominated all catches. Fish species composition was comprised mostly of freshwater (47%), followed by the marine (33%) and estuarine species (20%). Numerically, the marine euryhaline Chelon richardsonii and solely estuarine Gilchristella aestuaria were the dominant species in the estuary region (site 1 - 11) with 95% and 4% contribution, respectively. Chelon richardsonii also dominated all catches (67%) upstream into the river (site 12 - 18), followed by freshwater Labeobarbus aeneus (13%) and Pseudocrenilabrus philander (8%). This highlights the point that besides the marine Chelon richardsonii, other species albeit marine, estuarine and freshwater are utilising unique areas within the OREC. Temporal differentiation in fish abundance (catch-per-unit-effort, CPUE), diversity, richness and evenness were higher in the high-flow season than the low-flow season. Mean CPUE was higher at the mouth of the estuary and declined upstream into the river, whilst species diversity (including richness and evenness) increased upstream. High catches but low species diversity observed close to the mouth of the estuary were attributed to the domination of Chelon richardsonii. However, species diversity increased upstream in the river due to the dominance of freshwater fishes coupled with several marine and estuarine species. This diversity patterns were inconsistent with the general Remane and revised model for estuaries, hence a new RiverEstuarine Continuum concept suitable for OREC was developed. With the exception of Chelon richardsonii, spatial variability in the length-frequency distribution of most fishes was observed. Physico-chemical drivers provided valuable information on adaptation limits of species movement and distribution. Fishes were structured along a salinity gradient and interaction between temperature and salinity influenced community structure and diversity patterns in the OREC. Fish species utilising the lower OREC are predominantly zoobenthivores but a few detritivores/planktivores dominate numerically. Trophic inferences from stable isotope analysis showed increased carbon isotope values (δ 13C) with salinity toward the mouth of the estuary, whilst nitrogen isotope values (δ 15N) increased upstream into the river. Ontogenetic shifts in the SI ratios of all five fish species (marine Chelon richardsonii; estuarine Gilchristella aestuaria; freshwater Labeobarbus aeneus, Pseudocrenilabrus philander and Mesobola brevianalis) were observed in the OREC. Variability in seasons and salinity gradient influenced the SI ratios of several fish species. Seasonal changes influenced the δ 13C ratios of all species, except for Labeobarbus aeneus and Pseudocrenilabrus philander whereas the δ 15N ratios of all species (except for Mesobola brevianalis) differed significantly between the high-flow and low-flow season. This can be due to their feeding on specific life-history stages, such as eggs, larvae, gametophytes, sporophytes or zoospores of prey. Stable isotope ratios revealed that Mesobola brevianalis fed at a higher trophic level than Chelon richardsonii and Gilchristella aestuaria. Mesobola brevianalis feed on planktonic crustacean and insects. Chelon richardsonii feed on a wide range of prey, with prey switching between planktonic and detritivore food resources, whilst Gilchristella aestuaria feed selectively on zooplankton but switched to filter feeding modes in turbid water. Generally, δ 15N SI ratios increase with growth, however, for Labeobarbus aeneus, it was significantly higher in small size length than in large size individuals, probably because most of the juveniles assessed were caught upstream where δ 15N increases. Juveniles of Labeobarbus aeneus mainly feed on zoobenthos whilst in larger fish phytoplankton becomes increasingly important, suggesting the possibility that zoobenthos was more 15N enriched than plant materials. The trophic niches of Mesobola brevianalis were isotopically distinguishable from Chelon richardsonii and Gilchristella aestuaria during the low-flow season, revealing that these species are probably accessing carbon sources from different food chains. During high-flow season, the isotopic niche overlapped among several species, indicating that these species are probably deriving carbon sources from the same or similar food chains. Results from Layman isotope-based metrics revealed that Chelon richardsonii, Pseudocrenilabrus philander and Labeobarbus aeneus occupied the widest isotopic niche in the lower OREC, suggesting that these species are utilising food sources which may be derived from a wide variety of carbon sources. Mesobola brevianalis had the narrowest isotopic niche, however this does not imply "a narrow range of food sources’’ for the species. Overall, the potential carbon sources for selected fish species revealed that they are supported by a variety of food sources (mainly phyto-and zooplanktonic) or their food items constituted different basal sources which enable them to coexist. This study represents the first, integrated investigation of trophic relations among fishes of different origin using δ 13C and δ15N SI analyses. The current study provides a broader understanding of fish ecology within the River-Estuarine Continuum in the lower Orange River and estuary. By filling research gaps identified in the lower OREC, this synthesis of work also supports and informs management, conservation and responsible utilisation of estuarine fishery resources, in particular within the OREC.
- Full Text:
- Date Issued: 2020
Identifying a Successful Accounting Student: Profiling of Postgraduate Accounting Students in the Eastern Cape
- Authors: Weldon, Lana Joy
- Date: 2020
- Subjects: Personality -- South Africa -- Eastern Cape , Accounting -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50699 , vital:42343
- Description: Throughput rates and transformation have long been considered major challenges to accounting departments in South Africa. While much research has been done on various aspects of study techniques in an attempt to assist students to succeed, little attention has been paid to profiling students to ascertain whether there are common traits in terms of personality, aptitude, values and motives, which distinguish successful students from others. This study looks at these factors and uses sub-tests of the Differential Aptitude Test (DAT), selected with reference to the South African Institute of Chartered Accountants (SAICA) Competency Framework, to determine the correlation between these aptitudes and the success of accounting students. In addition, the impact of biographical data, including gender, race and type of school attended, is considered on the success of the students and the individual sub-tests of aptitude. The study then considers the impact of various personality types, personality traits and values on the success or failure of accounting students, and finally seeks to ascertain whether there is a holistic profile of a student who has a statistically significant chance of succeeding in accounting studies. Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended. accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended.
- Full Text:
- Date Issued: 2020
- Authors: Weldon, Lana Joy
- Date: 2020
- Subjects: Personality -- South Africa -- Eastern Cape , Accounting -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50699 , vital:42343
- Description: Throughput rates and transformation have long been considered major challenges to accounting departments in South Africa. While much research has been done on various aspects of study techniques in an attempt to assist students to succeed, little attention has been paid to profiling students to ascertain whether there are common traits in terms of personality, aptitude, values and motives, which distinguish successful students from others. This study looks at these factors and uses sub-tests of the Differential Aptitude Test (DAT), selected with reference to the South African Institute of Chartered Accountants (SAICA) Competency Framework, to determine the correlation between these aptitudes and the success of accounting students. In addition, the impact of biographical data, including gender, race and type of school attended, is considered on the success of the students and the individual sub-tests of aptitude. The study then considers the impact of various personality types, personality traits and values on the success or failure of accounting students, and finally seeks to ascertain whether there is a holistic profile of a student who has a statistically significant chance of succeeding in accounting studies. Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended. accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended.
- Full Text:
- Date Issued: 2020
Identifying the causes of widespread illegal dumping in Buffalo City Metropolitan Municipality and innovative waste management mechanism
- Authors: Brown, Drayton
- Date: 2020
- Subjects: Waste minimization -- law and legislation -- South Africa -- Buffalo City Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10948/49767 , vital:41798
- Description: South Africa faces the daily challenge of illegal dumping and authorities cannot seem to contain the problem. This is particularly the case in Buffalo City Metropolitan Municipality (BCMM) as the same non-effective means of curbing illegal dumping is attempted again and again. This study sought to gain insight into why residents would illegally dump waste near their homes considering the numerous negative health and environmental consequences. While many studies have focused on the quantitative aspects of waste management and illegal dumping, none have been conducted in the Eastern Cape or BCMM or enquired as to how citizens felt about the phenomena. This research utilised in-depth semi-structured interviews to gain insight into the problem of illegal dumping through the lenses of both residents and BCMM staff members. One of the key themes within the findings of the study is the apathetic nature of citizens towards their environment. There are also two predominant ways illegal dumping sites form. The first is through ‘Systemic Dumping’ which arises through the lack of waste infrastructure in low income communities and the second is ‘Ad-hoc Illegal Dumping’which form when BCMM does not provide a timely waste management service.
- Full Text:
- Date Issued: 2020
- Authors: Brown, Drayton
- Date: 2020
- Subjects: Waste minimization -- law and legislation -- South Africa -- Buffalo City Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10948/49767 , vital:41798
- Description: South Africa faces the daily challenge of illegal dumping and authorities cannot seem to contain the problem. This is particularly the case in Buffalo City Metropolitan Municipality (BCMM) as the same non-effective means of curbing illegal dumping is attempted again and again. This study sought to gain insight into why residents would illegally dump waste near their homes considering the numerous negative health and environmental consequences. While many studies have focused on the quantitative aspects of waste management and illegal dumping, none have been conducted in the Eastern Cape or BCMM or enquired as to how citizens felt about the phenomena. This research utilised in-depth semi-structured interviews to gain insight into the problem of illegal dumping through the lenses of both residents and BCMM staff members. One of the key themes within the findings of the study is the apathetic nature of citizens towards their environment. There are also two predominant ways illegal dumping sites form. The first is through ‘Systemic Dumping’ which arises through the lack of waste infrastructure in low income communities and the second is ‘Ad-hoc Illegal Dumping’which form when BCMM does not provide a timely waste management service.
- Full Text:
- Date Issued: 2020
Identifying the causes of widespread illegal dumping in buffalo city metropolitan municipality and innovative waste management mechanisms
- Authors: Brown, Drayton
- Date: 2020
- Subjects: Refuse and refuse disposal -- South Africa -- Eastern Cape , Municipal Services -- South Africa -- Eastern Cape Waste minimization -- South Africa -- Buffalo City Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/50444 , vital:42168
- Description: South Africa faces the daily challenge of illegal dumping and authorities cannot seem to contain the problem. This is particularly the case in Buffalo City Metropolitan Municipality (BCMM) as the same non-effective means of curbing illegal dumping is attempted again and again. This study sought to gain insight into why residents would illegally dump waste near their homes considering the numerous negative health and environmental consequences. While many studies have focused on the quantitative aspects of waste management and illegal dumping, none have been conducted in the Eastern Cape or BCMM or enquired as to how citizens felt about the phenomena. This research utilised in-depth semi-structured interviews to gain insight into the problem of illegal dumping through the lenses of both residents and BCMM staff members. One of the key themes within the findings of the study is the apathetic nature of citizens towards their environment. There are also two predominant ways illegal dumping sites form. The first is through ‘Systemic Dumping’ which arises through the lack of waste infrastructure in low income communities and the second is ‘Ad-hoc Illegal Dumping’ which form when BCMM does not provide a timely waste management service.
- Full Text:
- Date Issued: 2020
- Authors: Brown, Drayton
- Date: 2020
- Subjects: Refuse and refuse disposal -- South Africa -- Eastern Cape , Municipal Services -- South Africa -- Eastern Cape Waste minimization -- South Africa -- Buffalo City Metropolitan Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/50444 , vital:42168
- Description: South Africa faces the daily challenge of illegal dumping and authorities cannot seem to contain the problem. This is particularly the case in Buffalo City Metropolitan Municipality (BCMM) as the same non-effective means of curbing illegal dumping is attempted again and again. This study sought to gain insight into why residents would illegally dump waste near their homes considering the numerous negative health and environmental consequences. While many studies have focused on the quantitative aspects of waste management and illegal dumping, none have been conducted in the Eastern Cape or BCMM or enquired as to how citizens felt about the phenomena. This research utilised in-depth semi-structured interviews to gain insight into the problem of illegal dumping through the lenses of both residents and BCMM staff members. One of the key themes within the findings of the study is the apathetic nature of citizens towards their environment. There are also two predominant ways illegal dumping sites form. The first is through ‘Systemic Dumping’ which arises through the lack of waste infrastructure in low income communities and the second is ‘Ad-hoc Illegal Dumping’ which form when BCMM does not provide a timely waste management service.
- Full Text:
- Date Issued: 2020
Impact of climate finance on environmental quality in Sub-Sahara Africa
- Authors: Doku, Isaac
- Date: 2020
- Subjects: Climatic changes -- Economic aspects , Economic development -- Environmental aspects Macroeconomics -- Econometric models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50513 , vital:42206
- Description: Most climate finances available to Sub-Sahara Africa countries tries to assist governmental and non-governmental institutions decarbonise by reducing greenhouse gases or promote conservation of forests through REDD+ programs. On that backdrop, three main general objectives arises for this study; (1) to examine the impact of climate finance on greenhouse gas emissions (2) To find the impact of climate finance on deforestation in Sub-Sahara Africa (3) To determine the major recipient characteristics that attracts more climate finance to Sub-Sahara Africa. The first general objective looked at three greenhouse gas variables; carbon emission, methane and nitrous oxide emission. Data was analysed using system GMM for all countries in Sub-Sahara Africa for the period 2006-2017 based on data availability. The first general objective of the study employed system GMM robust standard errors and triangulates the result by using DOLS and FMOLS for robustness check. The findings show that climate finance is not reducing nitrous oxide, methane and total greenhouse gas emissions into the atmosphere, whereas carbon emission showed mixed results. System GMM results affirmed the existence of EKC, but DOLS and FMOLS results gave a contradictory finding. Based on that, we cannot conclude the existence of EKC for our studies. Energy consumption showed a positive significant impact on carbon, methane and total greenhouse gas for all three models in accordance to prior studies and affirming pollution haven hypothesis, but a mixed result for nitrous oxide. Finally, the findings from governance readiness showed governments in Africa’s unwillingness to reduce carbon but very keen in reducing the other greenhouses gases for all three models. Existence of pollution haven hypothesis shows that more hazardous and dirty investments are moving from developed countries to developing countries with less strict environmental rules like Sub-Sahara Africa. The second and third general objectives of the study employed system-GMM estimation technique to take care of time series variations in the data, as well as capture the unobserved country-specific time-invariant effect. Three and four stages hierarchical regressions are carried out for objectives two and three respectively and a panel quantile regression is employed to test sensitivity of the results for both analysis. The findings for objective two showed that increase in climate climate finance increases deforestation in two models and one model showing a decrease in deforestation, making the result very difficult to interpret and mixed. The study did not also get support for EKC but indicated that forest transition curve is rather U-shaped for all countries in Sub-Sahara Africa and two sub-regional blocks; EAC and CEMAC. Population growth and agricultural land use have been found to be major drivers of deforestation. Most of the governance indicators showed adverse impact on deforestation. The result for objective three indicates that Sub-Sahara African countries with high population growth rate, higher poverty levels, better ease of doing business profile, weaker governance policies, weaker control of corruption, stronger rule of law enforcement, deepened social inequality and better ICT usage have attracted more climate finance. Based on that, we recommend Africa countries to strengthen their practice of rule of law and more stringent rules to prevent or minimize corruption in the system. Climate finance managers should also undertake rigorous monitoring and supervision when funds are extended to reduce misappropriation of funds by recipients.
- Full Text:
- Date Issued: 2020
- Authors: Doku, Isaac
- Date: 2020
- Subjects: Climatic changes -- Economic aspects , Economic development -- Environmental aspects Macroeconomics -- Econometric models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50513 , vital:42206
- Description: Most climate finances available to Sub-Sahara Africa countries tries to assist governmental and non-governmental institutions decarbonise by reducing greenhouse gases or promote conservation of forests through REDD+ programs. On that backdrop, three main general objectives arises for this study; (1) to examine the impact of climate finance on greenhouse gas emissions (2) To find the impact of climate finance on deforestation in Sub-Sahara Africa (3) To determine the major recipient characteristics that attracts more climate finance to Sub-Sahara Africa. The first general objective looked at three greenhouse gas variables; carbon emission, methane and nitrous oxide emission. Data was analysed using system GMM for all countries in Sub-Sahara Africa for the period 2006-2017 based on data availability. The first general objective of the study employed system GMM robust standard errors and triangulates the result by using DOLS and FMOLS for robustness check. The findings show that climate finance is not reducing nitrous oxide, methane and total greenhouse gas emissions into the atmosphere, whereas carbon emission showed mixed results. System GMM results affirmed the existence of EKC, but DOLS and FMOLS results gave a contradictory finding. Based on that, we cannot conclude the existence of EKC for our studies. Energy consumption showed a positive significant impact on carbon, methane and total greenhouse gas for all three models in accordance to prior studies and affirming pollution haven hypothesis, but a mixed result for nitrous oxide. Finally, the findings from governance readiness showed governments in Africa’s unwillingness to reduce carbon but very keen in reducing the other greenhouses gases for all three models. Existence of pollution haven hypothesis shows that more hazardous and dirty investments are moving from developed countries to developing countries with less strict environmental rules like Sub-Sahara Africa. The second and third general objectives of the study employed system-GMM estimation technique to take care of time series variations in the data, as well as capture the unobserved country-specific time-invariant effect. Three and four stages hierarchical regressions are carried out for objectives two and three respectively and a panel quantile regression is employed to test sensitivity of the results for both analysis. The findings for objective two showed that increase in climate climate finance increases deforestation in two models and one model showing a decrease in deforestation, making the result very difficult to interpret and mixed. The study did not also get support for EKC but indicated that forest transition curve is rather U-shaped for all countries in Sub-Sahara Africa and two sub-regional blocks; EAC and CEMAC. Population growth and agricultural land use have been found to be major drivers of deforestation. Most of the governance indicators showed adverse impact on deforestation. The result for objective three indicates that Sub-Sahara African countries with high population growth rate, higher poverty levels, better ease of doing business profile, weaker governance policies, weaker control of corruption, stronger rule of law enforcement, deepened social inequality and better ICT usage have attracted more climate finance. Based on that, we recommend Africa countries to strengthen their practice of rule of law and more stringent rules to prevent or minimize corruption in the system. Climate finance managers should also undertake rigorous monitoring and supervision when funds are extended to reduce misappropriation of funds by recipients.
- Full Text:
- Date Issued: 2020
Impact of fracking fluid on Karoo plants based on field and greenhouse experiments
- Authors: Liddell, Duncan Carlyle
- Date: 2020
- Subjects: Plants -- South Africa -- Little Karoo , Desert ecology -- South Africa Great Karoo (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49125 , vital:41603
- Description: Fracking fluid has been indicated to be detrimental to vegetation. In forest vegetation the fracking fluid caused ground vegetation to be extensively damaged with high mortality rates and trees showing premature leaf loss following application. A study by Martin (2017) investigated these effects on Karoo vegetation in a greenhouse and found it to increase stress and reduced the growth with some life forms being identified as sensitive. The current study followed on the work of Martin testing additional species in the same greenhouse and applying different treatments of fracking fluid to Karoo vegetation in their habitat. The plants were monitored by measuring their height, photosynthetic efficiency (stress), biomass allocation and the temperature of the sites. The greenhouse plants had increased growth associated with repeated fracking fluid treatments while having variable stress levels with different treatments of the fracking fluid. The farm had mixed results being generally more stressed due to the treatments, the repeated fracking fluid treatments showed greater growth. The farm vegetation was more sensitive due to prolonged drought which is suspected to play a large role in the different response to fracking fluid between the two sites. The several hypotheses based on the finding of Martin (2017) were not supported by the data in this study. However, the application of fracking fluid did affect the tree species as they were found to be sensitive, while the other plant species was generally stressed after the applications. The greenhouse study cannot accurately represent the effects of fracking fluid on the farm vegetation, due to the large difference in the environment thus, more field studies would need to be conducted to determine the effects of fracking fluid.
- Full Text:
- Date Issued: 2020
- Authors: Liddell, Duncan Carlyle
- Date: 2020
- Subjects: Plants -- South Africa -- Little Karoo , Desert ecology -- South Africa Great Karoo (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49125 , vital:41603
- Description: Fracking fluid has been indicated to be detrimental to vegetation. In forest vegetation the fracking fluid caused ground vegetation to be extensively damaged with high mortality rates and trees showing premature leaf loss following application. A study by Martin (2017) investigated these effects on Karoo vegetation in a greenhouse and found it to increase stress and reduced the growth with some life forms being identified as sensitive. The current study followed on the work of Martin testing additional species in the same greenhouse and applying different treatments of fracking fluid to Karoo vegetation in their habitat. The plants were monitored by measuring their height, photosynthetic efficiency (stress), biomass allocation and the temperature of the sites. The greenhouse plants had increased growth associated with repeated fracking fluid treatments while having variable stress levels with different treatments of the fracking fluid. The farm had mixed results being generally more stressed due to the treatments, the repeated fracking fluid treatments showed greater growth. The farm vegetation was more sensitive due to prolonged drought which is suspected to play a large role in the different response to fracking fluid between the two sites. The several hypotheses based on the finding of Martin (2017) were not supported by the data in this study. However, the application of fracking fluid did affect the tree species as they were found to be sensitive, while the other plant species was generally stressed after the applications. The greenhouse study cannot accurately represent the effects of fracking fluid on the farm vegetation, due to the large difference in the environment thus, more field studies would need to be conducted to determine the effects of fracking fluid.
- Full Text:
- Date Issued: 2020
Impacts of cattle grazing pressure on vegetation and soil characteristics in an arid grassland of South Africa
- Authors: Botha, Gert Stephanus
- Date: 2020
- Subjects: Grazing -- Environmental aspects -- South Africa , Cattle -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/${Handle} , vital:39749
- Description: Natural rangelands are often degraded due to the implementation of incorrect grazing systems. One potential solution is the use of short duration, high intensity grazing. The impacts of this grazing system on, inter alia, vegetation and soil properties have not yet been comprehensively tested within the arid rangelands of South Africa. This study aimed to determine the impacts of grazing intensity on vegetation composition, forage quantity and quality, and soil compaction, soil water infiltration rates and soil chemical properties in an arid grassland in South Africa. The following three grazing treatments were compared: no grazing (NG), low intensity grazing (LIG) and high intensity grazing (HIG). A total of 18 plots (six replicates per treatment) were grazed with Bonsmara cattle. Each plot, 4 ha in size, was surveyed pre-grazing, directly after grazing, and again three, six and 12 months post-grazing. The results indicated that different grazing intensities did not affect grass diversity and the veld condition a year after grazing. Phytomass was influenced by grazing intensity, with no grazing having the highest phytomass throughout the study period. Soil compaction differed among seasons but not among treatments, with summer surveys recording the lowest soil compaction rates. The soil water infiltration rates did not differ between the three different treatments, indicating that grazing intensity did not affect infiltration rates. However, grazing did seem to improve soil nutrient levels when compared to NG. The grazed treatments had higher NH4+, K+, and organic carbon than the NG treatment. Nevertheless, there was no significant difference in nutrients levels when comparing the LIG system to the HIG system. When comparing the soil nutrients levels within a treatment over time, only the HIG treatment showed an increase in soil nutrient levels (Mg2+) over time, whereas the LIG and NG treatments showed no changed throughout the study period. Generally, the study results indicated that in the short term there was no advantage to using higher grazing intensity, although the presence of grazing (as opposed to no grazing) is advantageous to arid grassland functioning.
- Full Text:
- Date Issued: 2020
- Authors: Botha, Gert Stephanus
- Date: 2020
- Subjects: Grazing -- Environmental aspects -- South Africa , Cattle -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/${Handle} , vital:39749
- Description: Natural rangelands are often degraded due to the implementation of incorrect grazing systems. One potential solution is the use of short duration, high intensity grazing. The impacts of this grazing system on, inter alia, vegetation and soil properties have not yet been comprehensively tested within the arid rangelands of South Africa. This study aimed to determine the impacts of grazing intensity on vegetation composition, forage quantity and quality, and soil compaction, soil water infiltration rates and soil chemical properties in an arid grassland in South Africa. The following three grazing treatments were compared: no grazing (NG), low intensity grazing (LIG) and high intensity grazing (HIG). A total of 18 plots (six replicates per treatment) were grazed with Bonsmara cattle. Each plot, 4 ha in size, was surveyed pre-grazing, directly after grazing, and again three, six and 12 months post-grazing. The results indicated that different grazing intensities did not affect grass diversity and the veld condition a year after grazing. Phytomass was influenced by grazing intensity, with no grazing having the highest phytomass throughout the study period. Soil compaction differed among seasons but not among treatments, with summer surveys recording the lowest soil compaction rates. The soil water infiltration rates did not differ between the three different treatments, indicating that grazing intensity did not affect infiltration rates. However, grazing did seem to improve soil nutrient levels when compared to NG. The grazed treatments had higher NH4+, K+, and organic carbon than the NG treatment. Nevertheless, there was no significant difference in nutrients levels when comparing the LIG system to the HIG system. When comparing the soil nutrients levels within a treatment over time, only the HIG treatment showed an increase in soil nutrient levels (Mg2+) over time, whereas the LIG and NG treatments showed no changed throughout the study period. Generally, the study results indicated that in the short term there was no advantage to using higher grazing intensity, although the presence of grazing (as opposed to no grazing) is advantageous to arid grassland functioning.
- Full Text:
- Date Issued: 2020
Inclusion in organisations following disability
- Authors: Durrheim, Zenita Beth
- Date: 2020
- Subjects: People with disabilities -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/47818 , vital:40380
- Description: Given the prevalence of disability in South Africa and specifically amongst the working population, this study explores the experiences of individuals who have been rendered disabled following injury and have returned to work. This study used a qualitative research design, specifically from an interpretative perspective to gain an understanding of individuals’ experiences of inclusion in organisations following disability due to injury. The phenomenological approach was best suited to this study in terms of its provision of valuable data collection directly from the participants, based on their own unique experiences. The research methodology was based on a multiple case study approach. Semi-structured interviews were conducted with 11 identified participants through purposive sampling. Through thematic analysis, five themes of inclusion were identified including ‘supportive relationships’, ‘organisational support, accommodation and policies’, ‘nature of the working environment’, ‘work ability and financial implications’ and finally ‘personal well-being’. Furthermore, for each of the primary themes, 12 sub-themes were identified. These themes and sub-themes were explored in relation to participant experiences of inclusion as well as linking specific literature of inclusion, return-to-work and disability models to the themes presented. Linking the findings to existing theoretical models of inclusion provided context with many of the themes identified also evident within the theoretical models. The factors identified within the themes of inclusion were conceptualised at different systemic levels with eight factors identified at the macro-organisational level, nine factors at the meso-group level and eight factors at the micro-group level. These identified factors could aid organisations and policymakers to ensure the effective inclusion of individuals with disabilities in organisations.
- Full Text:
- Date Issued: 2020
- Authors: Durrheim, Zenita Beth
- Date: 2020
- Subjects: People with disabilities -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/47818 , vital:40380
- Description: Given the prevalence of disability in South Africa and specifically amongst the working population, this study explores the experiences of individuals who have been rendered disabled following injury and have returned to work. This study used a qualitative research design, specifically from an interpretative perspective to gain an understanding of individuals’ experiences of inclusion in organisations following disability due to injury. The phenomenological approach was best suited to this study in terms of its provision of valuable data collection directly from the participants, based on their own unique experiences. The research methodology was based on a multiple case study approach. Semi-structured interviews were conducted with 11 identified participants through purposive sampling. Through thematic analysis, five themes of inclusion were identified including ‘supportive relationships’, ‘organisational support, accommodation and policies’, ‘nature of the working environment’, ‘work ability and financial implications’ and finally ‘personal well-being’. Furthermore, for each of the primary themes, 12 sub-themes were identified. These themes and sub-themes were explored in relation to participant experiences of inclusion as well as linking specific literature of inclusion, return-to-work and disability models to the themes presented. Linking the findings to existing theoretical models of inclusion provided context with many of the themes identified also evident within the theoretical models. The factors identified within the themes of inclusion were conceptualised at different systemic levels with eight factors identified at the macro-organisational level, nine factors at the meso-group level and eight factors at the micro-group level. These identified factors could aid organisations and policymakers to ensure the effective inclusion of individuals with disabilities in organisations.
- Full Text:
- Date Issued: 2020
Index of coordination for swimming and running in triathletes: a comparative study
- Authors: Van Den Bergh, Katelyne Mei
- Date: 2020
- Subjects: Triathletes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46406 , vital:39598
- Description: The primary aim of this study was to compare the Index of Coordination (IdC) for both sprint and endurance swimming and running of less-skilled level triathletes. The researchutilised a quantitative approach, specifically exploratory, with a one group post-test-only research design. Twenty participants from the triathlon community, ages 18 years and older, were selected via purposive and convenient sampling. The participants were expected to complete a total of four physical tests, namely 50 m sprint swim, 1500 m endurance swim, 50 m sprint run,and 5000 m endurance run, on four separate days, over a period of two weeks. The data was collected by video recording each participant performing each of the four different tests andcoded frame-by-frame onDartfish Video Solution (10.0).The IdCwas derived by identifying the time-in markers and time-out markers for both left and right arms when swimming; and by identifying the time-on markers and time-off markers for both left and right legs when running. The results revealed significant differencesbetweenthe IdCvalues ofsprint swimming and endurance swimming(p<0.001); sprint running andendurance running(p<0.001); sprint swimming andsprint running(p<0.001); andendurance swimmingandendurance running(p<0.001).The top performersin each testwere significantly faster than bottom performers(sprint swimming: p<0.001; sprint running:p<0.001; endurance swimming: p<0.001; endurance running: p<0.001) but no significant group differences on associated IdC were found(sprint swimming: p=0.535; sprint running: p=0.857; endurance swimming: p=0.132; endurance running: p=0.775).Bothendurance tests were divided into three equal portions and it was found that 23% ofthe fastest trial endurance swim time can be explained by the IdC obtained in portion three(p=0.032); and that 62% of the fastest trial endurance run time can be explained by the IdC obtained in portion one(p<0.001). The overall findings of the study suggest that an IdC mode is considered efficient relative to the environmental contextand thatIdCis relative to skill level or alternatively independent of performance times. The IdC, therefore, remains inconclusive as an alternative method but warrants further investigation particularly in longer distance endurance events.
- Full Text:
- Date Issued: 2020
- Authors: Van Den Bergh, Katelyne Mei
- Date: 2020
- Subjects: Triathletes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46406 , vital:39598
- Description: The primary aim of this study was to compare the Index of Coordination (IdC) for both sprint and endurance swimming and running of less-skilled level triathletes. The researchutilised a quantitative approach, specifically exploratory, with a one group post-test-only research design. Twenty participants from the triathlon community, ages 18 years and older, were selected via purposive and convenient sampling. The participants were expected to complete a total of four physical tests, namely 50 m sprint swim, 1500 m endurance swim, 50 m sprint run,and 5000 m endurance run, on four separate days, over a period of two weeks. The data was collected by video recording each participant performing each of the four different tests andcoded frame-by-frame onDartfish Video Solution (10.0).The IdCwas derived by identifying the time-in markers and time-out markers for both left and right arms when swimming; and by identifying the time-on markers and time-off markers for both left and right legs when running. The results revealed significant differencesbetweenthe IdCvalues ofsprint swimming and endurance swimming(p<0.001); sprint running andendurance running(p<0.001); sprint swimming andsprint running(p<0.001); andendurance swimmingandendurance running(p<0.001).The top performersin each testwere significantly faster than bottom performers(sprint swimming: p<0.001; sprint running:p<0.001; endurance swimming: p<0.001; endurance running: p<0.001) but no significant group differences on associated IdC were found(sprint swimming: p=0.535; sprint running: p=0.857; endurance swimming: p=0.132; endurance running: p=0.775).Bothendurance tests were divided into three equal portions and it was found that 23% ofthe fastest trial endurance swim time can be explained by the IdC obtained in portion three(p=0.032); and that 62% of the fastest trial endurance run time can be explained by the IdC obtained in portion one(p<0.001). The overall findings of the study suggest that an IdC mode is considered efficient relative to the environmental contextand thatIdCis relative to skill level or alternatively independent of performance times. The IdC, therefore, remains inconclusive as an alternative method but warrants further investigation particularly in longer distance endurance events.
- Full Text:
- Date Issued: 2020
Influence of process energy on stress corrosion susceptibility of a friction hydro pillar repaired steam turbine rotor disc blade locating hole
- Authors: Pentz, Willem Gerhard
- Date: 2020
- Subjects: Friction welding , Mechanical engineering
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/47106 , vital:39810
- Description: Currently the power generation industry is struggling to keep older coal power plants running efficiently. One of the major hurdles is to keep repair and service cost low. Over time stress corrosion cracking (SCC) occurs in the locating pinholes of tier type rotors which locate the turbine blades. This is where this research aims to assist with an alternative repair technique, Friction Hydro Pillar Processing (FHPP) welding, to have longer service intervals thus saving cost and time. The same material can be used for welding and a new aligned hole can be drilled. FHPP welding is a solid state friction welding process. Four different FHPP axial forces were selected to compare their respective performance in subsequent tensile testing, impact testing and SCC testing. All the tensile samples extracted from preheated welds and post weld heat treated welds fracture in the parent material, which indicates good weld efficiency. The impact crack route from the weld nugget towards the parent material was identified in the energy and force graph. Axial force which promote impact toughness can be selected with this curve. SCC occurs when a tensile stress is applied to a susceptible material when in a conducive environment for cracking. A new SCC W-shape was designed and performed well during initial testing. With the SCC W-shape two specimens can be extracted opposite each other and tested. Both the preheated weld samples and the post weld heat treatment (PWHT) weld samples had improved SCC performance over their respective parent material samples. A high axial force, low process energy, and high process energy rate (low process energy and low weld time) produced a weld with improved SCC resistance. FHPP (with PWHT) is a promising repair technique as it improved on the SCC resistance and impact toughness as well as having 100% bond efficiency. More research is still required to identify the SCC mechanism of the FHPP weld.
- Full Text:
- Date Issued: 2020
- Authors: Pentz, Willem Gerhard
- Date: 2020
- Subjects: Friction welding , Mechanical engineering
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/47106 , vital:39810
- Description: Currently the power generation industry is struggling to keep older coal power plants running efficiently. One of the major hurdles is to keep repair and service cost low. Over time stress corrosion cracking (SCC) occurs in the locating pinholes of tier type rotors which locate the turbine blades. This is where this research aims to assist with an alternative repair technique, Friction Hydro Pillar Processing (FHPP) welding, to have longer service intervals thus saving cost and time. The same material can be used for welding and a new aligned hole can be drilled. FHPP welding is a solid state friction welding process. Four different FHPP axial forces were selected to compare their respective performance in subsequent tensile testing, impact testing and SCC testing. All the tensile samples extracted from preheated welds and post weld heat treated welds fracture in the parent material, which indicates good weld efficiency. The impact crack route from the weld nugget towards the parent material was identified in the energy and force graph. Axial force which promote impact toughness can be selected with this curve. SCC occurs when a tensile stress is applied to a susceptible material when in a conducive environment for cracking. A new SCC W-shape was designed and performed well during initial testing. With the SCC W-shape two specimens can be extracted opposite each other and tested. Both the preheated weld samples and the post weld heat treatment (PWHT) weld samples had improved SCC performance over their respective parent material samples. A high axial force, low process energy, and high process energy rate (low process energy and low weld time) produced a weld with improved SCC resistance. FHPP (with PWHT) is a promising repair technique as it improved on the SCC resistance and impact toughness as well as having 100% bond efficiency. More research is still required to identify the SCC mechanism of the FHPP weld.
- Full Text:
- Date Issued: 2020