An eco-physiological investigation of fisheries-induced evolution: comparing the resilience of larvae from exploited and unexploited commercial reef fish populations to projected ocean acidification
- Authors: Muller, Cuen
- Date: 2022-04-08
- Subjects: Ocean acidification , Fishes Climatic factors , Fishes Physiology , Fishes Metabolism , Fishes Respiration , Fishes Larvae , Fishery management , Chrysoblephus laticeps (Red roman)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232579 , vital:50004 , DOI 10.21504/10962/232579
- Description: It is now accepted that anthropogenic-induced climate change is resulting in unprecedented rates of change to marine environments. Marine organisms are being challenged by rapidly increasing temperatures, acidification, expansion of oxygen dead zones, and higher frequencies and magnitudes of extreme weather events. Exploited fish populations are also undergoing selective harvesting. Certain traits, such as large size, fast growth, and/or bold/active behaviours, are being actively targeted and removed from the population gene pool. This selective removal of individuals may compromise the capacity of fish populations to resist or recover from environmental disturbances and reduce their ability to adapt to a changing environment as many of these traits are heritable. As most marine fishes' embryonic and larval stages represent the period when individuals are most sensitive to environmental disturbances, they are a critical bottleneck to population persistence in the face of exploitation and climate change. This thesis aimed to quantify and compare the metabolic physiology, growth, and development of an exploited and endemic sparid, the roman seabream Chrysoblephus laticeps, during the early larval stages under 1) ocean acidification conditions expected by the year 2100 and 2) from populations experiencing dissimilar rates of exploitation. To quantify and compare the physiology of larvae, adult C. laticeps from an exploited population were captured and field-spawned. Fertilised eggs were placed into either control/present-day conditions (pH = 8.03, pCO2 ≈ 420 μatm) or high-pCO2/hypercapnic treatment conditions (pH = 7.63, pCO2 ≈ 1400 μatm). The metabolic physiology of individual larvae was determined using a novel rolling-regression technique on static respirometry data. Here, estimates of the minimum and maximum oxygen consumption rates (VO2) could be determined with high test-retest reliability. The very early developmental stages (yolk-sac stage) appeared resilient to high pCO2 conditions despite being exposed to treatment conditions throughout the embryonic stage. Preflexion larvae showed sensitivity to treatment conditions by exhibiting reduced metabolic and growth rates, consistent with metabolic depression, associated with environmental stress. However, by the onset of flexion, which coincides with gill development, acid-base regulation, and muscle differentiation, metabolic and growth rates of treatment larvae were significantly greater than that of controls. This suggests that acid-base regulation imposes a high cost to maintain internal pH homeostasis. Importantly, these elevated metabolic costs were likely mediated through increased feeding rates in experimental conditions where food was ad libitum. In natural conditions, where food availability may be varied, high pCO2 conditions could be associated with higher mortality rates. Based on evidence that protected/unexploited populations are more genetically diverse and are composed of individuals representing a greater range of metabolic phenotypes, offspring were collected from a protected population experiencing otherwise similar environmental conditions to the exploited population. Metabolic rates of control larvae were generally similar to those of the exploited population. However, minimum rates of VO2 were typically higher for larvae from the protected population at comparable life stages. Preflexion treatment larvae from the protected population did not appear to undergo a period of reduced metabolism or growth compared to their control counterparts. While metabolic rates at the onset of flexion were significantly higher for treatment larvae, this was not associated with growth differences. Growth over-compensation following periods of growth depression is often associated with deleterious effects, such as organ damage and body or developmental malformations. This suggests somewhat improved resilience to ocean acidification conditions. This thesis found evidence that larval C. laticeps are sensitive to ocean acidification conditions expected by 2100. When this stressor is combined with increasing thermal variability, changing current coastal regimes, and heterogeneous food availability, also expected to occur by 2100, ocean acidification may compromise the population persistence of this species. However, an energetics approach to stress-tolerance suggests that larvae from the protected population may inherently show greater resilience to climate change-related environmental stressors. Evidence that exploitation affects the resilience of fish larvae to climate change highlights the need for an evolutionary approach to fisheries management and the importance of spatial protection in maintaining larger and more resilient populations while providing the raw material essential for adaptation. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Muller, Cuen
- Date: 2022-04-08
- Subjects: Ocean acidification , Fishes Climatic factors , Fishes Physiology , Fishes Metabolism , Fishes Respiration , Fishes Larvae , Fishery management , Chrysoblephus laticeps (Red roman)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232579 , vital:50004 , DOI 10.21504/10962/232579
- Description: It is now accepted that anthropogenic-induced climate change is resulting in unprecedented rates of change to marine environments. Marine organisms are being challenged by rapidly increasing temperatures, acidification, expansion of oxygen dead zones, and higher frequencies and magnitudes of extreme weather events. Exploited fish populations are also undergoing selective harvesting. Certain traits, such as large size, fast growth, and/or bold/active behaviours, are being actively targeted and removed from the population gene pool. This selective removal of individuals may compromise the capacity of fish populations to resist or recover from environmental disturbances and reduce their ability to adapt to a changing environment as many of these traits are heritable. As most marine fishes' embryonic and larval stages represent the period when individuals are most sensitive to environmental disturbances, they are a critical bottleneck to population persistence in the face of exploitation and climate change. This thesis aimed to quantify and compare the metabolic physiology, growth, and development of an exploited and endemic sparid, the roman seabream Chrysoblephus laticeps, during the early larval stages under 1) ocean acidification conditions expected by the year 2100 and 2) from populations experiencing dissimilar rates of exploitation. To quantify and compare the physiology of larvae, adult C. laticeps from an exploited population were captured and field-spawned. Fertilised eggs were placed into either control/present-day conditions (pH = 8.03, pCO2 ≈ 420 μatm) or high-pCO2/hypercapnic treatment conditions (pH = 7.63, pCO2 ≈ 1400 μatm). The metabolic physiology of individual larvae was determined using a novel rolling-regression technique on static respirometry data. Here, estimates of the minimum and maximum oxygen consumption rates (VO2) could be determined with high test-retest reliability. The very early developmental stages (yolk-sac stage) appeared resilient to high pCO2 conditions despite being exposed to treatment conditions throughout the embryonic stage. Preflexion larvae showed sensitivity to treatment conditions by exhibiting reduced metabolic and growth rates, consistent with metabolic depression, associated with environmental stress. However, by the onset of flexion, which coincides with gill development, acid-base regulation, and muscle differentiation, metabolic and growth rates of treatment larvae were significantly greater than that of controls. This suggests that acid-base regulation imposes a high cost to maintain internal pH homeostasis. Importantly, these elevated metabolic costs were likely mediated through increased feeding rates in experimental conditions where food was ad libitum. In natural conditions, where food availability may be varied, high pCO2 conditions could be associated with higher mortality rates. Based on evidence that protected/unexploited populations are more genetically diverse and are composed of individuals representing a greater range of metabolic phenotypes, offspring were collected from a protected population experiencing otherwise similar environmental conditions to the exploited population. Metabolic rates of control larvae were generally similar to those of the exploited population. However, minimum rates of VO2 were typically higher for larvae from the protected population at comparable life stages. Preflexion treatment larvae from the protected population did not appear to undergo a period of reduced metabolism or growth compared to their control counterparts. While metabolic rates at the onset of flexion were significantly higher for treatment larvae, this was not associated with growth differences. Growth over-compensation following periods of growth depression is often associated with deleterious effects, such as organ damage and body or developmental malformations. This suggests somewhat improved resilience to ocean acidification conditions. This thesis found evidence that larval C. laticeps are sensitive to ocean acidification conditions expected by 2100. When this stressor is combined with increasing thermal variability, changing current coastal regimes, and heterogeneous food availability, also expected to occur by 2100, ocean acidification may compromise the population persistence of this species. However, an energetics approach to stress-tolerance suggests that larvae from the protected population may inherently show greater resilience to climate change-related environmental stressors. Evidence that exploitation affects the resilience of fish larvae to climate change highlights the need for an evolutionary approach to fisheries management and the importance of spatial protection in maintaining larger and more resilient populations while providing the raw material essential for adaptation. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-04-08
An epistemic justice account of students’ experiences of feedback
- Authors: Vilakazi, Bella Phetheni
- Date: 2022-04-08
- Subjects: Feedback (Psychology) , Experience , Narrative inquiry (Research method) , Critical thinking , Caring Moral and ethical aspects , Epistemic access
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232599 , vital:50006 , DOI 10.21504/10962/232599
- Description: I am a storyteller. I believe in the power of stories to share experiences and to elucidate thoughts and ideas and to help us to make sense of complex social practices. This thesis includes the stories of five young women who were learning to become teachers. As they shared their stories with me, I share them with you. This study includes their stories of receiving feedback. These stories are structured within the Narrative Inquiry dimensions of temporality, place and context. These dimensions suggest that stories are historical and move through time, stories are shaped by place and the context in which they unfold (Clandinin, 2013). Furthermore, these stories demonstrate how feedback can serve to give access to powerful knowledge and can serve to recognise who our students are and what they bring to the academy (Hordern, 2018). But feedback can also serve to misrecognise. Much has been written and reported about the barriers preventing students from acting on the feedback on their assignment tasks in higher education. In this study, I argue that feedback is a pedagogic practice that can support students to gain epistemic access. Feedback can only achieve this if it makes the expectations explicit for students to make sense of and make meaning for themselves and if it is offered in a dialogical format which recognises the students, their attempts, their identities, and their knowledge. The research question of this study, ‘How do experiences of forms of feedback affect female undergraduate student teachers’ chances of epistemic access?’, is not unusual. There have been many research projects that have been carried out that examine students’ experiences of feedback (for example, Evans, 2013; Basey, Maines, & Francis, 2014; Nicol et al.; 2014; Carless, 2019; Winstone et al., 2021). But I identified a gap where feedback has not, to my knowledge, been studied directly through the lenses of Epistemic Justice towards Parity of Participation. This study interpreted five undergraduate student teachers’ feedback experiences through these lenses. Narrative inquiry enabled me to design this study in ways that foregrounded experience. Data was collected through multiple conversations during which I organised the participants’ life stories of feedback within the dimensions of temporality, place and context, and sociality. Miranda Fricker’s (2007) theory of Epistemic Justice and Fraser’s norm of Parity of Participation (2000) framed this study. I engaged with Fricker and Fraser’s literature meaningfully as a reader and researcher. I established an understanding of how the lenses offered by Fraser and Fricker allowed me to make sense of the literature more generally, in social life and on the pedagogic practice of feedback. Fricker’s theory of Epistemic Justice considers the epistemically unjust, gendered, raced and classed, experiences of epistemic agents. Fricker (2007) draws on two central concepts to account for epistemic injustices: Testimonial Injustice and Hermeneutical Injustice. Fricker (2007; 2003) explains that testimonial injustice occurs within a testimonial exchange setting, when an epistemic agent as a speaker gives testimony of the epistemic agent’s experiences and knowledge but is not awarded the credibility the speaker deserves (Fricker, 2003). Epistemic agents who participate in a testimonial exchange need to overcome bias and prejudice in order to evaluate testimonies with the degree of fairness the testimony deserves (Fricker, 2013; 2016). Hermeneutical injustice occurs when an epistemic agent is unable to make sense and make meaning of their social experiences. Hermeneutical injustice strengthens when the epistemic agent is prevented from gaining access to resources that might help with sense making and meaning making of these social experiences (Dielman, 2012; Fricker, 2016). To ensure that meaning can be made between people and groups of people, there needs to be some shared understandings of the purpose and process of sense making and meaning-making – or a willingness to co-create such shared understandings. Fraser’s norm of Participatory Parity enabled a consideration of the larger world of political and economic systems that give rise to social injustice. In this study, the theories of Fricker and Fraser are used to illuminate experiences of feedback of the five undergraduate student teachers who are the participants in this study and how these translate to epistemic and social injustice. The norm of Participatory Parity is considered where feedback allowed or restricted participants from participating on an equal footing in the feedback process. Narrative inquiry, a research methodology that is used to study experiences, was used to inform research strategies of this study. Participants’ experiences, data collection and organising the narratives demonstrated the dimensions of temporality and space. The thesis includes biographical vignettes for each of the participants in the study, interspersed with data from across all five participants. The key findings of this study show that feedback generally operates at the surface levels of grammar correction. In light of the theoretical lenses of this study, I argue that the feedback experiences they shared generally did not recognise their attempts and the identities and knowledges they brought to the tasks. Because the focus was on superficial correction of the specific task, the feedback failed to create conditions for the (re)distribution of knowledge. At times the feedback exerted power on participants. Because the feedback was generally in the form of one directional correction (with little space for interaction with the feedback or dialogue with the assessor), this caused status subordination of participants in the epistemic spaces of teaching practice. Lastly, the lack of clarity of feedback was harmful to the potential for dialogical feedback. Such feedback caused participants to experience forms of epistemic injustice in the form of hermeneutical injustice where it failed to create conditions for the distribution of knowledge. Feedback also caused participants to experience testimonial injustice where it failed to create conditions for recognising participants’ processes of sense-making and meaning-making in the various assignment tasks. Participatory Parity could not occur because the processes of recognition and redistribution were constrained. Feedback then created fertile conditions of epistemic injustice to occur, and participants were likely to have failed to gain the much needed epistemic access. This study is not the story of bad, uncaring academics; the study acknowledges the context of large classes and heavy workloads in which feedback is or is not given. Rather, this is the story of five women trying to make their way through the university and out into the world as teachers. The study calls for better theorising of feedback and more support for both academics and students to develop feedback literacy so that feedback might serve as a dialogical pedagogic practice that enables epistemic justice. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Vilakazi, Bella Phetheni
- Date: 2022-04-08
- Subjects: Feedback (Psychology) , Experience , Narrative inquiry (Research method) , Critical thinking , Caring Moral and ethical aspects , Epistemic access
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232599 , vital:50006 , DOI 10.21504/10962/232599
- Description: I am a storyteller. I believe in the power of stories to share experiences and to elucidate thoughts and ideas and to help us to make sense of complex social practices. This thesis includes the stories of five young women who were learning to become teachers. As they shared their stories with me, I share them with you. This study includes their stories of receiving feedback. These stories are structured within the Narrative Inquiry dimensions of temporality, place and context. These dimensions suggest that stories are historical and move through time, stories are shaped by place and the context in which they unfold (Clandinin, 2013). Furthermore, these stories demonstrate how feedback can serve to give access to powerful knowledge and can serve to recognise who our students are and what they bring to the academy (Hordern, 2018). But feedback can also serve to misrecognise. Much has been written and reported about the barriers preventing students from acting on the feedback on their assignment tasks in higher education. In this study, I argue that feedback is a pedagogic practice that can support students to gain epistemic access. Feedback can only achieve this if it makes the expectations explicit for students to make sense of and make meaning for themselves and if it is offered in a dialogical format which recognises the students, their attempts, their identities, and their knowledge. The research question of this study, ‘How do experiences of forms of feedback affect female undergraduate student teachers’ chances of epistemic access?’, is not unusual. There have been many research projects that have been carried out that examine students’ experiences of feedback (for example, Evans, 2013; Basey, Maines, & Francis, 2014; Nicol et al.; 2014; Carless, 2019; Winstone et al., 2021). But I identified a gap where feedback has not, to my knowledge, been studied directly through the lenses of Epistemic Justice towards Parity of Participation. This study interpreted five undergraduate student teachers’ feedback experiences through these lenses. Narrative inquiry enabled me to design this study in ways that foregrounded experience. Data was collected through multiple conversations during which I organised the participants’ life stories of feedback within the dimensions of temporality, place and context, and sociality. Miranda Fricker’s (2007) theory of Epistemic Justice and Fraser’s norm of Parity of Participation (2000) framed this study. I engaged with Fricker and Fraser’s literature meaningfully as a reader and researcher. I established an understanding of how the lenses offered by Fraser and Fricker allowed me to make sense of the literature more generally, in social life and on the pedagogic practice of feedback. Fricker’s theory of Epistemic Justice considers the epistemically unjust, gendered, raced and classed, experiences of epistemic agents. Fricker (2007) draws on two central concepts to account for epistemic injustices: Testimonial Injustice and Hermeneutical Injustice. Fricker (2007; 2003) explains that testimonial injustice occurs within a testimonial exchange setting, when an epistemic agent as a speaker gives testimony of the epistemic agent’s experiences and knowledge but is not awarded the credibility the speaker deserves (Fricker, 2003). Epistemic agents who participate in a testimonial exchange need to overcome bias and prejudice in order to evaluate testimonies with the degree of fairness the testimony deserves (Fricker, 2013; 2016). Hermeneutical injustice occurs when an epistemic agent is unable to make sense and make meaning of their social experiences. Hermeneutical injustice strengthens when the epistemic agent is prevented from gaining access to resources that might help with sense making and meaning making of these social experiences (Dielman, 2012; Fricker, 2016). To ensure that meaning can be made between people and groups of people, there needs to be some shared understandings of the purpose and process of sense making and meaning-making – or a willingness to co-create such shared understandings. Fraser’s norm of Participatory Parity enabled a consideration of the larger world of political and economic systems that give rise to social injustice. In this study, the theories of Fricker and Fraser are used to illuminate experiences of feedback of the five undergraduate student teachers who are the participants in this study and how these translate to epistemic and social injustice. The norm of Participatory Parity is considered where feedback allowed or restricted participants from participating on an equal footing in the feedback process. Narrative inquiry, a research methodology that is used to study experiences, was used to inform research strategies of this study. Participants’ experiences, data collection and organising the narratives demonstrated the dimensions of temporality and space. The thesis includes biographical vignettes for each of the participants in the study, interspersed with data from across all five participants. The key findings of this study show that feedback generally operates at the surface levels of grammar correction. In light of the theoretical lenses of this study, I argue that the feedback experiences they shared generally did not recognise their attempts and the identities and knowledges they brought to the tasks. Because the focus was on superficial correction of the specific task, the feedback failed to create conditions for the (re)distribution of knowledge. At times the feedback exerted power on participants. Because the feedback was generally in the form of one directional correction (with little space for interaction with the feedback or dialogue with the assessor), this caused status subordination of participants in the epistemic spaces of teaching practice. Lastly, the lack of clarity of feedback was harmful to the potential for dialogical feedback. Such feedback caused participants to experience forms of epistemic injustice in the form of hermeneutical injustice where it failed to create conditions for the distribution of knowledge. Feedback also caused participants to experience testimonial injustice where it failed to create conditions for recognising participants’ processes of sense-making and meaning-making in the various assignment tasks. Participatory Parity could not occur because the processes of recognition and redistribution were constrained. Feedback then created fertile conditions of epistemic injustice to occur, and participants were likely to have failed to gain the much needed epistemic access. This study is not the story of bad, uncaring academics; the study acknowledges the context of large classes and heavy workloads in which feedback is or is not given. Rather, this is the story of five women trying to make their way through the university and out into the world as teachers. The study calls for better theorising of feedback and more support for both academics and students to develop feedback literacy so that feedback might serve as a dialogical pedagogic practice that enables epistemic justice. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2022
- Full Text:
- Date Issued: 2022-04-08
Demersal fish distribution in the shallow marine nearshore and estuarine seascape of Algoa Bay: Nursery areas and the effect of environmental drivers
- Authors: Nodo, Phakama
- Date: 2022-04-08
- Subjects: Groundfishes South Africa Algoa Bay , Estuarine fishes South Africa Algoa Bay , Marine nurseries South Africa Algoa Bay , Estuarine fishes Habitat South Africa Algoa Bay , Estuarine fishes Physiology South Africa Algoa Bay , Estuarine fishes Effect of pollution on South Africa Algoa Bay , Estuarine fishes Larvae South Africa Algoa Bay , Estuarine fishes Effect of human beings on South Africa Algoa Bay
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232399 , vital:49988 , DOI 10.21504/10962/232399
- Description: Estuaries and shallow marine nearshore areas are highly productive and valuable ecosystems, which provide numerous habitats for fish and support fundamental ecological links with other environments. Assessing fish distribution across estuarine and marine nearshore habitats is important to identify ecologically important habitats and develop effective management strategies for coastal fishes, many of which are important fishery species. Despite this, only a few studies have focussed on fish community patterns across an estuary and marine nearshore gradient concurrently, particularly including early life history stages, to determine the nursery value of both environments, and to examine whether these two coastal environments have distinct fish assemblages in relation to physical factors. The main aim of this study was to assess the environmental drivers of demersal fish communities in soft-bottom benthic habitats in two permanently open estuaries and adjacent marine nearshore areas (5 – 10 m) of Algoa Bay, South Africa, as well as to assess the relative roles of these two habitats as settlement and nursery areas for demersal fish species. A 1.5 m, conical shoeless beam trawl net was used to sample the demersal fish community concurrently in each habitat between July 2017 and September 2019. Sampling was conducted in July 2017, February, March, May, July, August, October and November 2019 and February, April and September 2019. DNA barcoding was used to verify identification of the early life history stages of fish caught in the estuarine and marine nearshore areas of Algoa Bay. In addition, since the two estuaries (Swartkops and Sundays) are heavily polluted, the effect of low dissolved oxygen and hypoxia and associated shifts in spatial distribution of demersal species was investigated. The two sampled estuaries had a higher abundance of demersal fishes, with a total of 6437 fishes (28 species) caught (3752 and 2685 individuals with 24 and 20 species recorded in the Sundays and Swartkops estuaries, respectively). Species richness was higher in the marine nearshore of Algoa Bay, with 29 species (797 individuals) caught. Of the 7234 individuals caught, the identification of 100 specimens, in either a larval or early juvenile phase, were uncertain and therefore DNA barcoding was used to verify their identification. Of these 100 individuals, 86 were positively identified to species level using COI sequences. Fourteen failed to amplify by PCR and could only be identified morphologically. The marine nearshore sites were dominated by species which spawn in the marine environment and are not dependent on estuaries (marine species and marine estuary-opportunists), whilst the estuaries were dominated by estuarine spawners or marine spawners dependent on estuaries to some degree. Two discrete demersal fish assemblages were identified representing the marine nearshore and the estuary, with no significant differences observed between the two estuaries (Sundays and Swartkops). The differences observed between the marine nearshore and estuary were mostly driven by salinity, turbidity, silt and organic content of the sediment. These distinct fish assemblages might be considered as indicators for the respective environments they inhabit. Both habitats were dominated by early life history stages (larvae to juveniles), indicating the nursery function of both habitats. Early life stages collectively comprised 97% of the catch in the marine nearshore and 68% in the estuary. Young-of-the-year (YOY) juveniles (< 1-year-old juveniles) and transformation stages (when changes in body shape and pigment pattern occur) dominated the total catch in the marine nearshore, while YOY juveniles dominated the estuarine fish assemblages. Ariidae Galeichthys feliceps, Haemulidae Pomadasys olivaceus, Sciaenidae Argyrosomus inodorus and Cynoglossidae Cynoglossus zanzibarensis, comprised the largest proportion of YOY juveniles in the marine nearshore. The transformation stage in the marine nearshore was numerically dominated by P. olivaceus and G. feliceps. In the estuarine environment, YOY juveniles were mostly dominated by Sparidae Rhabdosargus holubi, Soleidae Heteromycteris capensis and Gobiidae Caffrogobius gilchristi. The greatest abundance of early life stage fishes was observed in the lower reaches of the Sundays Estuary and the upper reaches of the Swartkops Estuary, as well as nearshore sites located in close proximity to the estuary mouths, particularly during spring and summer. Despite the fact that these coastal ecosystems are important nursery areas, they are threatened by a number of factors, including habitat loss and modification due to urban development, intensification of agriculture and subsequent eutrophication, climate change, and overfishing, all of which reduce ecosystem functioning and reduce the ecological and economic value of these habitats around the world. Hypoxia is one of the major threats to the functioning of coastal ecosystems, particularly estuaries. The Sundays and Swartkops estuaries both experience persistent eutrophic conditions, with frequent phytoplankton blooms (> 20 μg Chl-a l-1) that result in instances of bottom water oxygen depletion (< 4 mg/l). During the present study in the Sundays Estuary, low oxygen waters were recorded in the middle reaches (Site S5) mostly during summer (four months of low DO conditions). In the Swartkops Estuary, low dissolved oxygen was recorded in the upper reaches during spring. The lowest dissolved oxygen concentration recorded was 0.5 mg/l and 2.4 mg/l in the bottom waters of the Sundays and Swartkops estuaries, respectively. Selected dominant species were only absent from areas where dissolved oxygen was < 1 mg/l and present in the adjacent sites (for example Site S4, and S3) where DO was higher mostly during January 2019. As such, the low dissolved oxygen concentrations recorded in the Swartkops Estuary did not have a noticeable impact on fish distribution, although the total abundance of species did show a slight decline when dissolved oxygen was < 3 mg/l. This study demonstrates the importance of concurrently examining estuarine and nearshore marine habitats in order to identify ecologically important habitats, which has important implications for the development of effective management strategies for coastal fish populations, particularly in the light of anthropogenic change. In addition, in order to identify nursery hotspots it is crucial to correctly identify all the species occupying these areas. As such, this study confirms the importance of also using DNA barcoding for fish identification, particularly for the early life history stages of cryptic species (e.g. Argyrosomus inodorus and Argyrosomus japonicus). , Thesis (PhD) -- Faculty of Science, Ichthyology & Fisheries Sciences, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Nodo, Phakama
- Date: 2022-04-08
- Subjects: Groundfishes South Africa Algoa Bay , Estuarine fishes South Africa Algoa Bay , Marine nurseries South Africa Algoa Bay , Estuarine fishes Habitat South Africa Algoa Bay , Estuarine fishes Physiology South Africa Algoa Bay , Estuarine fishes Effect of pollution on South Africa Algoa Bay , Estuarine fishes Larvae South Africa Algoa Bay , Estuarine fishes Effect of human beings on South Africa Algoa Bay
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232399 , vital:49988 , DOI 10.21504/10962/232399
- Description: Estuaries and shallow marine nearshore areas are highly productive and valuable ecosystems, which provide numerous habitats for fish and support fundamental ecological links with other environments. Assessing fish distribution across estuarine and marine nearshore habitats is important to identify ecologically important habitats and develop effective management strategies for coastal fishes, many of which are important fishery species. Despite this, only a few studies have focussed on fish community patterns across an estuary and marine nearshore gradient concurrently, particularly including early life history stages, to determine the nursery value of both environments, and to examine whether these two coastal environments have distinct fish assemblages in relation to physical factors. The main aim of this study was to assess the environmental drivers of demersal fish communities in soft-bottom benthic habitats in two permanently open estuaries and adjacent marine nearshore areas (5 – 10 m) of Algoa Bay, South Africa, as well as to assess the relative roles of these two habitats as settlement and nursery areas for demersal fish species. A 1.5 m, conical shoeless beam trawl net was used to sample the demersal fish community concurrently in each habitat between July 2017 and September 2019. Sampling was conducted in July 2017, February, March, May, July, August, October and November 2019 and February, April and September 2019. DNA barcoding was used to verify identification of the early life history stages of fish caught in the estuarine and marine nearshore areas of Algoa Bay. In addition, since the two estuaries (Swartkops and Sundays) are heavily polluted, the effect of low dissolved oxygen and hypoxia and associated shifts in spatial distribution of demersal species was investigated. The two sampled estuaries had a higher abundance of demersal fishes, with a total of 6437 fishes (28 species) caught (3752 and 2685 individuals with 24 and 20 species recorded in the Sundays and Swartkops estuaries, respectively). Species richness was higher in the marine nearshore of Algoa Bay, with 29 species (797 individuals) caught. Of the 7234 individuals caught, the identification of 100 specimens, in either a larval or early juvenile phase, were uncertain and therefore DNA barcoding was used to verify their identification. Of these 100 individuals, 86 were positively identified to species level using COI sequences. Fourteen failed to amplify by PCR and could only be identified morphologically. The marine nearshore sites were dominated by species which spawn in the marine environment and are not dependent on estuaries (marine species and marine estuary-opportunists), whilst the estuaries were dominated by estuarine spawners or marine spawners dependent on estuaries to some degree. Two discrete demersal fish assemblages were identified representing the marine nearshore and the estuary, with no significant differences observed between the two estuaries (Sundays and Swartkops). The differences observed between the marine nearshore and estuary were mostly driven by salinity, turbidity, silt and organic content of the sediment. These distinct fish assemblages might be considered as indicators for the respective environments they inhabit. Both habitats were dominated by early life history stages (larvae to juveniles), indicating the nursery function of both habitats. Early life stages collectively comprised 97% of the catch in the marine nearshore and 68% in the estuary. Young-of-the-year (YOY) juveniles (< 1-year-old juveniles) and transformation stages (when changes in body shape and pigment pattern occur) dominated the total catch in the marine nearshore, while YOY juveniles dominated the estuarine fish assemblages. Ariidae Galeichthys feliceps, Haemulidae Pomadasys olivaceus, Sciaenidae Argyrosomus inodorus and Cynoglossidae Cynoglossus zanzibarensis, comprised the largest proportion of YOY juveniles in the marine nearshore. The transformation stage in the marine nearshore was numerically dominated by P. olivaceus and G. feliceps. In the estuarine environment, YOY juveniles were mostly dominated by Sparidae Rhabdosargus holubi, Soleidae Heteromycteris capensis and Gobiidae Caffrogobius gilchristi. The greatest abundance of early life stage fishes was observed in the lower reaches of the Sundays Estuary and the upper reaches of the Swartkops Estuary, as well as nearshore sites located in close proximity to the estuary mouths, particularly during spring and summer. Despite the fact that these coastal ecosystems are important nursery areas, they are threatened by a number of factors, including habitat loss and modification due to urban development, intensification of agriculture and subsequent eutrophication, climate change, and overfishing, all of which reduce ecosystem functioning and reduce the ecological and economic value of these habitats around the world. Hypoxia is one of the major threats to the functioning of coastal ecosystems, particularly estuaries. The Sundays and Swartkops estuaries both experience persistent eutrophic conditions, with frequent phytoplankton blooms (> 20 μg Chl-a l-1) that result in instances of bottom water oxygen depletion (< 4 mg/l). During the present study in the Sundays Estuary, low oxygen waters were recorded in the middle reaches (Site S5) mostly during summer (four months of low DO conditions). In the Swartkops Estuary, low dissolved oxygen was recorded in the upper reaches during spring. The lowest dissolved oxygen concentration recorded was 0.5 mg/l and 2.4 mg/l in the bottom waters of the Sundays and Swartkops estuaries, respectively. Selected dominant species were only absent from areas where dissolved oxygen was < 1 mg/l and present in the adjacent sites (for example Site S4, and S3) where DO was higher mostly during January 2019. As such, the low dissolved oxygen concentrations recorded in the Swartkops Estuary did not have a noticeable impact on fish distribution, although the total abundance of species did show a slight decline when dissolved oxygen was < 3 mg/l. This study demonstrates the importance of concurrently examining estuarine and nearshore marine habitats in order to identify ecologically important habitats, which has important implications for the development of effective management strategies for coastal fish populations, particularly in the light of anthropogenic change. In addition, in order to identify nursery hotspots it is crucial to correctly identify all the species occupying these areas. As such, this study confirms the importance of also using DNA barcoding for fish identification, particularly for the early life history stages of cryptic species (e.g. Argyrosomus inodorus and Argyrosomus japonicus). , Thesis (PhD) -- Faculty of Science, Ichthyology & Fisheries Sciences, 2022
- Full Text:
- Date Issued: 2022-04-08
Environmental governance, agency and multi-actor dynamics in Southern Africa
- Authors: Falayi, Menelisi
- Date: 2022-04-08
- Subjects: Environmental law South Africa , Environmental law Zimbabwe , Natural resources Management , Conservation of natural resources South Africa Eastern Cape , Natural resources Co-management South Africa Eastern Cape , Range policy South Africa Eastern Cape , Range management South Africa Eastern Cape , Forest reserves Law and legislation Zimbabwe , Agent (Philosophy)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232355 , vital:49984 , DOI 10.21504/10962/232355
- Description: Natural resources have, since the beginning of time, played a central role in supporting human wellbeing. In southern Africa resource consumption has drastically increased over the past 50 years, resulting in biodiversity loss and land degradation. To reduce land degradation and biodiversity loss rates in the region, great emphasis has been placed on building effective governance structures that can deliver environmentally and socially sustainable outcomes. However, environmental governance continues to be a major challenge in the management and conservation of natural resources in the region. Thus, there is renewed scientific and policy interest in strengthening the capacity of governance systems. This thesis is timely; there is an increasing desire by policymakers and land users in the region to develop governance options that enhance multi-actor participation and collaboration. Therefore, this thesis explores the dynamics that influence the capacity of natural resource governance systems in southern Africa, predominately in Machubeni, South Africa (chapters 3 and 4) and in State forests in Zimbabwe (chapter 5). To achieve this aim, four stand-alone manuscripts that answer the following questions are included: 1. How have governance challenges manifested in natural resource management between 2010 and 2020 in southern Africa? 2. How were the governance objectives and attributes applied per historical period and what were the influencing drivers? a. What key drivers influenced rangeland condition over time in Machubeni? 3. How have multi-actor ties changed since the external investment in landscape governance and management in Machubeni, South Africa? 4. What role has agency played in the effectiveness of co-management initiatives in southern Africa? To answer the questions, I applied Bennett and Satterfield’s practical framework for understanding the objectives, attributes and elements of governance and Archer’s ii morphogenetic framework. The study employed a mixed-methods approach which included a scoping review methodology (chapter 2), household surveys, historical records, life history interviews, focus group discussions (chapters 3 and 4), social network analysis (chapter 4) and secondary data analysis (chapter 5). Results from the scoping review (chapter 2) show that research on governance challenges has not increased since 2010. Results suggest that governance challenges related to the maintenance of system integrity and functioning, specifically lack of coordination, accountability, skills, and resources to define effective natural resource management, were the most reported in the literature. Chapter 3 elucidates the importance of history in evaluating the application of governance objectives and rangeland condition in resource-poor areas. The results show that the residual impacts of the ‘ghost of environmental history’ still influence governance dynamics in Machubeni, South Africa. Furthermore, contemporary challenges are linked to history. Chapter 4 shows that transformative spaces enhance collaboration and knowledge sharing between land users, government, and researchers. Finally, chapter 5 employs the morphogenetic framework to assess how agency (the capacity of people and organisations to make choices and decisions about their lives) influenced the effectiveness of co-management initiatives in southern Africa. The results suggest that in attempts to shift governance towards greater effectiveness, more attention should be paid to building individual and group agency. Based on the results from the empirical chapters, the study identified three key focus areas that require more attention in order to build effective landscape governance and management in southern Africa:(i) acknowledging the role of historical legacies and context,(ii) building and developing agency, capacity and trust amongst actors and (iii) the development of sustainable landscape financing mechanisms that will enable governance systems to deliver socially and environmentally sustainable outcomes. , Ubutyebi bendalo buqhubekile budlala indima ebalulekileyo ekuxhaseni impilo-ntle yoluntu. Ngenxa yokubaluleka kobutyebi bendalo kubomi babantu, ukusetyenziswa kobutyebi kuye kwanda kakhulu kule minyaka eyi-50 idlulileyo, okubangela ulahleko lweentlobo-ntlobo yezityalo nezilwanyana eziphilayo kunye nokhukhuliseko komhlaba kumazantsi e-Afrika. Ukunciphisa ukhukhuliseko komhlaba kunye namazinga alahleko eentlobo-ntlobo zezityalo nezilwanyana eziphilayo kummandla, ugxininiso olukhulu luye lwabekwa ekwakhiweni kweziseko zolawulo ezisebenzayo ezinokuzisa iziphumo ezizinzileyo ngokwemeko yendalo nentlalo. Nangona kunjalo, ulawulo lwendalo lusaqhubeka lungumceli mngeni omkhulu kulawulo nolondolozo lobutyebi bendalo kulo mmandla. Ngoko ke, kukho umdla ohlaziyiweyo wenzululwazi nomgaqo-nkqubo ekomelezeni isakhono seenkqubo zolawulo. Le ithisisi ifike ngexesha kuba kukho umnqweno okhulayo kummandla ngabaqulunqi bomgaqo-nkqubo kunye nabasebenzisi bomhlaba ukuphuhlisa iinketho zolawulo eziphakamisa ukuthatha inxaxheba kwabantu abaninzi kunye nentsebenziswano. Ke ngoko, le ithisisi iphonononga izinto eziphembelela isakhono seenkqubo zolawulo lobutyebi bendalo kumazantsi eAfrika, ikakhulu eMachubeni, eMzantsi Afrika (isahluko 3 no 4) nakumahlathi kaRhulumente eZimbabwe (isahluko 5). Ukuphumeza le njongo, kufakwe layo: 1. Ibonakaliswe njani imiceli mngeni yolawulo kulawulo lwendalo phakathi ko-2010 no 2020 kumazantsi eAfrika? 2. Zeziphi injongo zolawulo kunye neempawu ezisetyenzisiweyo ngokwexesha lembali? a. Zeziphi ezona zinto eziqhuba phambili eziphembelele ukusetyenziswa kweenjongo zolawulo kunye neempawu ngokuhamba kwexesha? b. Zeziphi iindlela ezibalulekileyo ezichaphazele ngayo iimeko zamadlelo ekuhambeni kwexesha? 3. Atshintshe njani amakhonkco obudlelwane phakathi kwabathathi-nxaxheba ukusukela oko kutyalo-mali lwangaphandle kulawulo lobume bomhlaba eMachubeni, eMzantsi Afrika? 4. Yiyiphi indima edlalwe sisakhono sokwenza ukhetho kunye nezigqibo malunga nobomi bakho ekusebenzeni ngempumelelo kwamalinge olawulo ngokubambisana kumazantsi e-Afrika? Ukuphendula imibuzo, ndisebenzise isakhelo esisebenzayo sikaBennett kunye noSatterfield ukuqonda iinjongo kunye neempawu zolawulo kunye nesakhelo se-Archer's morphogenetic. Uphononongo lusebenzise iindlela ezixubeneyo ezibandakanya indlela yokuphonononga iincwadi zophando (isahluko 2), uphando lwamakhaya, iirekhodi zembali, udliwano-ndlebe lwembali yobomi, iingxoxo zeqela eligxininisiweyo (isahluko 3 kunye no 4), uhlalutyo lonxibelelwano nobudlelwane boluntu (isahluko 4) kunye nohlalutyo lwedatha ethathwe ngomnye umntu. (isahluko 5). Iziphumo ezivela kuphononongo lweencwadi zophando (isahluko 2) zibonakalisa ukuba uphando ngemiceli mngeni yolawulo alunyukanga ukusukela ngo-2010. Iziphumo zibonisa ukuba imiceli mngeni yolawulo enxulumene nokugcinwa kwemfezeko nokusebenza kwenkqubo, ngokukodwa ukungabikho kolungelelwaniso, uxanduva, izakhono, kunye nezibonelelo zokuchaza ulawulo lwemithombo yendalo olusebenzayo, yayiyeyona ichazwe kwiincwadi. Isahluko sesi-3 sicacisa ukubaluleka kwembali ekuvavanyeni ukusetyenziswa kweenjongo zolawulo kunye nemeko yemihlaba ekwiindawo ezihlwempuzekileyo ngezibonelelo. Iziphumo zibonisa ukuba uchaphazeleko oshiyekileyo we-‘ghost of environmental history’ zisenefuthe kulawulo lwenguquko eMachubeni, eMzantsi Afrika. Ngaphezu koko, imiceli mngeni yangoku inxulunyaniswa nembali. Isahluko sesi-4 sibonisa ukuba iindawo eziguqulayo ziphucula intsebenziswano nokwabelana ngolwazi phakathi kwabasebenzisi bomhlaba, urhulumente nabaphandi. Ekugqibeleni, isahluko sesi-5 sisebenzisa isakhelo se-morphogenetic ukuvavanya indlela isakhono sabantu kunye nemibutho sokwenza ukhetho kunye nezigqibo malunga nobomi babo ibe nefuthe ekusebenzeni kwamanyathelo olawulo ngokubambisana kumazantsi e-Afrika. Iziphumo zibonisa ukuba kwiinzame zokutshintsha ulawulo ukuze lusebenze kangangoko, ingqwalasela engaphezulu kufuneka ibekwe ekwakheni isakhono, somntu neseqela, sokwenza ukhetho kunye nezigqibo malunga nobomi babo. Ngokusekelwe kwiziphumo ezivela kwizahluko zobungqina, uphononongo luchonge imiba emithathu engundoqo ekugxilwe kuzo ezifuna ingqwalaselo ethe kratya ukuze kwakhiwe ulawulo lwemihlaba olusebenzayo kumazantsi e-Afrika. Ngokukodwa: (i) ukuqaphela indima yelifa lembali kunye nomxholo (ii) ukwakha nokuphuhlisa isakhono v sokwenza ukhetho kunye nezigqibo malunga nobomi, isakhono kunye nokuthembana phakathi kwabathathi-nxaxheba kunye (iii) nokuphuhliswa kweendlela ezizinzileyo zenkxaso-mali yendawo eziya kwenza ukuba iinkqubo zolawulo zinike iziphumo ezizinzileyo ngokwentlalo nendalo. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Falayi, Menelisi
- Date: 2022-04-08
- Subjects: Environmental law South Africa , Environmental law Zimbabwe , Natural resources Management , Conservation of natural resources South Africa Eastern Cape , Natural resources Co-management South Africa Eastern Cape , Range policy South Africa Eastern Cape , Range management South Africa Eastern Cape , Forest reserves Law and legislation Zimbabwe , Agent (Philosophy)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232355 , vital:49984 , DOI 10.21504/10962/232355
- Description: Natural resources have, since the beginning of time, played a central role in supporting human wellbeing. In southern Africa resource consumption has drastically increased over the past 50 years, resulting in biodiversity loss and land degradation. To reduce land degradation and biodiversity loss rates in the region, great emphasis has been placed on building effective governance structures that can deliver environmentally and socially sustainable outcomes. However, environmental governance continues to be a major challenge in the management and conservation of natural resources in the region. Thus, there is renewed scientific and policy interest in strengthening the capacity of governance systems. This thesis is timely; there is an increasing desire by policymakers and land users in the region to develop governance options that enhance multi-actor participation and collaboration. Therefore, this thesis explores the dynamics that influence the capacity of natural resource governance systems in southern Africa, predominately in Machubeni, South Africa (chapters 3 and 4) and in State forests in Zimbabwe (chapter 5). To achieve this aim, four stand-alone manuscripts that answer the following questions are included: 1. How have governance challenges manifested in natural resource management between 2010 and 2020 in southern Africa? 2. How were the governance objectives and attributes applied per historical period and what were the influencing drivers? a. What key drivers influenced rangeland condition over time in Machubeni? 3. How have multi-actor ties changed since the external investment in landscape governance and management in Machubeni, South Africa? 4. What role has agency played in the effectiveness of co-management initiatives in southern Africa? To answer the questions, I applied Bennett and Satterfield’s practical framework for understanding the objectives, attributes and elements of governance and Archer’s ii morphogenetic framework. The study employed a mixed-methods approach which included a scoping review methodology (chapter 2), household surveys, historical records, life history interviews, focus group discussions (chapters 3 and 4), social network analysis (chapter 4) and secondary data analysis (chapter 5). Results from the scoping review (chapter 2) show that research on governance challenges has not increased since 2010. Results suggest that governance challenges related to the maintenance of system integrity and functioning, specifically lack of coordination, accountability, skills, and resources to define effective natural resource management, were the most reported in the literature. Chapter 3 elucidates the importance of history in evaluating the application of governance objectives and rangeland condition in resource-poor areas. The results show that the residual impacts of the ‘ghost of environmental history’ still influence governance dynamics in Machubeni, South Africa. Furthermore, contemporary challenges are linked to history. Chapter 4 shows that transformative spaces enhance collaboration and knowledge sharing between land users, government, and researchers. Finally, chapter 5 employs the morphogenetic framework to assess how agency (the capacity of people and organisations to make choices and decisions about their lives) influenced the effectiveness of co-management initiatives in southern Africa. The results suggest that in attempts to shift governance towards greater effectiveness, more attention should be paid to building individual and group agency. Based on the results from the empirical chapters, the study identified three key focus areas that require more attention in order to build effective landscape governance and management in southern Africa:(i) acknowledging the role of historical legacies and context,(ii) building and developing agency, capacity and trust amongst actors and (iii) the development of sustainable landscape financing mechanisms that will enable governance systems to deliver socially and environmentally sustainable outcomes. , Ubutyebi bendalo buqhubekile budlala indima ebalulekileyo ekuxhaseni impilo-ntle yoluntu. Ngenxa yokubaluleka kobutyebi bendalo kubomi babantu, ukusetyenziswa kobutyebi kuye kwanda kakhulu kule minyaka eyi-50 idlulileyo, okubangela ulahleko lweentlobo-ntlobo yezityalo nezilwanyana eziphilayo kunye nokhukhuliseko komhlaba kumazantsi e-Afrika. Ukunciphisa ukhukhuliseko komhlaba kunye namazinga alahleko eentlobo-ntlobo zezityalo nezilwanyana eziphilayo kummandla, ugxininiso olukhulu luye lwabekwa ekwakhiweni kweziseko zolawulo ezisebenzayo ezinokuzisa iziphumo ezizinzileyo ngokwemeko yendalo nentlalo. Nangona kunjalo, ulawulo lwendalo lusaqhubeka lungumceli mngeni omkhulu kulawulo nolondolozo lobutyebi bendalo kulo mmandla. Ngoko ke, kukho umdla ohlaziyiweyo wenzululwazi nomgaqo-nkqubo ekomelezeni isakhono seenkqubo zolawulo. Le ithisisi ifike ngexesha kuba kukho umnqweno okhulayo kummandla ngabaqulunqi bomgaqo-nkqubo kunye nabasebenzisi bomhlaba ukuphuhlisa iinketho zolawulo eziphakamisa ukuthatha inxaxheba kwabantu abaninzi kunye nentsebenziswano. Ke ngoko, le ithisisi iphonononga izinto eziphembelela isakhono seenkqubo zolawulo lobutyebi bendalo kumazantsi eAfrika, ikakhulu eMachubeni, eMzantsi Afrika (isahluko 3 no 4) nakumahlathi kaRhulumente eZimbabwe (isahluko 5). Ukuphumeza le njongo, kufakwe layo: 1. Ibonakaliswe njani imiceli mngeni yolawulo kulawulo lwendalo phakathi ko-2010 no 2020 kumazantsi eAfrika? 2. Zeziphi injongo zolawulo kunye neempawu ezisetyenzisiweyo ngokwexesha lembali? a. Zeziphi ezona zinto eziqhuba phambili eziphembelele ukusetyenziswa kweenjongo zolawulo kunye neempawu ngokuhamba kwexesha? b. Zeziphi iindlela ezibalulekileyo ezichaphazele ngayo iimeko zamadlelo ekuhambeni kwexesha? 3. Atshintshe njani amakhonkco obudlelwane phakathi kwabathathi-nxaxheba ukusukela oko kutyalo-mali lwangaphandle kulawulo lobume bomhlaba eMachubeni, eMzantsi Afrika? 4. Yiyiphi indima edlalwe sisakhono sokwenza ukhetho kunye nezigqibo malunga nobomi bakho ekusebenzeni ngempumelelo kwamalinge olawulo ngokubambisana kumazantsi e-Afrika? Ukuphendula imibuzo, ndisebenzise isakhelo esisebenzayo sikaBennett kunye noSatterfield ukuqonda iinjongo kunye neempawu zolawulo kunye nesakhelo se-Archer's morphogenetic. Uphononongo lusebenzise iindlela ezixubeneyo ezibandakanya indlela yokuphonononga iincwadi zophando (isahluko 2), uphando lwamakhaya, iirekhodi zembali, udliwano-ndlebe lwembali yobomi, iingxoxo zeqela eligxininisiweyo (isahluko 3 kunye no 4), uhlalutyo lonxibelelwano nobudlelwane boluntu (isahluko 4) kunye nohlalutyo lwedatha ethathwe ngomnye umntu. (isahluko 5). Iziphumo ezivela kuphononongo lweencwadi zophando (isahluko 2) zibonakalisa ukuba uphando ngemiceli mngeni yolawulo alunyukanga ukusukela ngo-2010. Iziphumo zibonisa ukuba imiceli mngeni yolawulo enxulumene nokugcinwa kwemfezeko nokusebenza kwenkqubo, ngokukodwa ukungabikho kolungelelwaniso, uxanduva, izakhono, kunye nezibonelelo zokuchaza ulawulo lwemithombo yendalo olusebenzayo, yayiyeyona ichazwe kwiincwadi. Isahluko sesi-3 sicacisa ukubaluleka kwembali ekuvavanyeni ukusetyenziswa kweenjongo zolawulo kunye nemeko yemihlaba ekwiindawo ezihlwempuzekileyo ngezibonelelo. Iziphumo zibonisa ukuba uchaphazeleko oshiyekileyo we-‘ghost of environmental history’ zisenefuthe kulawulo lwenguquko eMachubeni, eMzantsi Afrika. Ngaphezu koko, imiceli mngeni yangoku inxulunyaniswa nembali. Isahluko sesi-4 sibonisa ukuba iindawo eziguqulayo ziphucula intsebenziswano nokwabelana ngolwazi phakathi kwabasebenzisi bomhlaba, urhulumente nabaphandi. Ekugqibeleni, isahluko sesi-5 sisebenzisa isakhelo se-morphogenetic ukuvavanya indlela isakhono sabantu kunye nemibutho sokwenza ukhetho kunye nezigqibo malunga nobomi babo ibe nefuthe ekusebenzeni kwamanyathelo olawulo ngokubambisana kumazantsi e-Afrika. Iziphumo zibonisa ukuba kwiinzame zokutshintsha ulawulo ukuze lusebenze kangangoko, ingqwalasela engaphezulu kufuneka ibekwe ekwakheni isakhono, somntu neseqela, sokwenza ukhetho kunye nezigqibo malunga nobomi babo. Ngokusekelwe kwiziphumo ezivela kwizahluko zobungqina, uphononongo luchonge imiba emithathu engundoqo ekugxilwe kuzo ezifuna ingqwalaselo ethe kratya ukuze kwakhiwe ulawulo lwemihlaba olusebenzayo kumazantsi e-Afrika. Ngokukodwa: (i) ukuqaphela indima yelifa lembali kunye nomxholo (ii) ukwakha nokuphuhlisa isakhono v sokwenza ukhetho kunye nezigqibo malunga nobomi, isakhono kunye nokuthembana phakathi kwabathathi-nxaxheba kunye (iii) nokuphuhliswa kweendlela ezizinzileyo zenkxaso-mali yendawo eziya kwenza ukuba iinkqubo zolawulo zinike iziphumo ezizinzileyo ngokwentlalo nendalo. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
Ethnobotany and conservation biology of Warburgia salutaris (G.Bertol.) Chiov., a threatened medicinal plant in southern Mozambique
- Authors: Senkoro, Annae Maria
- Date: 2022-04-08
- Subjects: Ethnobotany Mozambique , Conservation biology Mozambique , Canellaceae Habitat Mozambique , Canellaceae Genetics , Warburgia salutaris Habitat Mozambique , Warburgia salutaris Genetics , Endangered plants Mozambique , Biogeography Climatic factors Mozambique , Traditional medicine Mozambique , Traditional ecological knowledge Mozambique
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232967 , vital:50042 , DOI 10.21504/10962/232967
- Description: Warburgia salutaris, locally known as “chibaha” (Ronga, Tsonga), “isiBhaha” (Zulu) and “siBhaha” (Siswati), is one of the most highly-valued medicinal plant species in southern Africa. Its bark has long been employed to treat bacterial and fungal infections, and it is often a front line herbal treatment for malaria. The species is popular in rural and urban areas due to its lower price compared to commercial pharmaceuticals and because of its long-standing spiritual and symbolic significance. Consequently, W. salutaris is threatened in Malawi, South Africa and Swaziland and is believed to be extincted in the wild in Zimbabwe. In Mozambique, where the tree is confined to the southern part of the country, it is considered vulnerable due to high local demand and cross-border export. Although there is limited research, further work is urgently needed to provide the basis for options and strategies to achieve desired outcomes. This study aimed to explore different approaches for the conservation of W. salutaris in the Lebombo Mountains (LM), the Tembe River (TR) and the Futi Corridor (FC) areas, in southern Mozambique. For this, potential distribution, socio cultural factors that influenced sustainable management of the species, demography, harvest impact, genetic diversity and population differentiation were considered. The kuenm package in R, 2 846 occurrence and 11 environmental data were used to model the potential current and future distribution in 2050 and 2070 using four general circulation models (CESM1(BGC), ACCESS1.3, FIO-ESM and IPSL-CM5A-MR) under representative concentration pathways (RCPs) 4.5 and 8.5. The extent of occurrence (EOO) and habitat suitability (HS) were also determined. Stratified random semi-structured interviews with 182 heads of households were carried out to explore cultural and socio incentives of use, compared knowledge distribution, determine local management practices and explore local ecological knowledge related to the species in the three study areas. In addition, 17 focus group discussion were conducted to clarify issues raised during household interviews. One hundred and twenty four quadrants were used to determine the abundance and population structure. The Simpson index of dominance, permutation index and quotient between consecutive classes were used to assess population stability, and an eight point scale was used to evaluate the extent of bark damages. Genomic deoxyribonucleic acid (gDNA) (n=48) was used to assessed genetic diversity and population structure through the newly developed single sequence repeats (SSR) molecular markers. Model selected was statistical significant for prediction of potential distribution of W. salutaris in southern Mozambique (partial ROC =0.00, omission rate = 0.04 and delta AICc = 0.00). The current environmental conditions mostly explained by climatic predictor, indicated in general, the potential distribution on areas of occurrence observed during the field work in southern Mozambique. Future project suggested an increase of climatic suitable areas in all the general circulation models in both conservative and pessimistic climatic scenarios (RCPs 4.5 and 8.5, respectively) in 2050 and 2070, and consequently the increase of HS and the EOO. Results of this work suggests W. salutaris would not extinct at least in the coming 50 years due to climate change but other threats such as overexploitation of the species need to be addressed. With increase of climatic suitable areas, conservation and management of this species could focus on reintroduction and cultivation for recovery of the species, with the help of time. W. salutaris was used for medicinal purposes to treat 12 health problems, with the bark being the most commonly used part (92% of informants). Knowledge of the species uses differed significantly between the three study areas but not with respondent gender or age. Informants also mentioned a considerable number of alternative species of W. salutaris (37 species in LM, 33 species in TR and 17 species in FC). Local ecological knowledge on the ecological niche of the species also varied substantial in the three areas with both types of knowledge generally higher in the Tembe River area. Local management practises were revealed mostly on harvesting through vertical bark stripping cited by 100% of informants in TR, 61.6% FC and 51.7 LM (71% of all informants). Yet most (64.3% of all informants, corresponding to 98.4% in TR, 51.7% in Fc and 41.7% LM) used non-traditional harvesting tools (machete) bark removal. For sustainable use of the species, consideration should be given to combined conservation strategies such as the use of alternative species with the same application, substitution of bark by leaves, and increases in alternative sources of plant material through cultivation. The densities of alive stems were not statistically different in the three areas but was higher in LM (mean of 4500.3±9209.8 stems/ha). Equally the mean densities of recruits (diameter ≤2 cm) were not considerable different but was higher in the FC (3296.8±9116.7 stems/ha). The regression analyses for the three study area revealed negative slopes, indicating more recruits and fewer individuals in larger classes. The Simpson indexes of dominance, permutation indexes and quotients between the consecutive size classes suggested some levels of population instability in the three areas. Harvesting took place in the eight point scale, all size classes were harvested but preference was higher on intermediate (15.1-20 cm) or larger (>20 cm) size classes in all the study areas but gatherers avoided harvesting bark from recruits. Although the mean densities of harvested stem was not significant this work indicated higher levels of stem destruction in FC. Harvested dead stems ware significant in the three areas and FC had the higher of (39.5±85.9 stems/ha) compared to 7.6±19.1 and 2.1±4.3 in TR and LM, respectively. Equally, the density of physiologically stressed stems differed substantially in the three areas with higher in FC 20.5± 75.5 stems/ha compared to 18.7±82.9 stems/ha in TR and 3.8±11.8 stems/ha in LM. This results suggests implementation of protection measures such as the inclusion of the species in the national CITES list to regulated cross-border trade and strengthening of the law enforcement. Genetic diversity, structure and gene flow in the exiting populations of southern Mozambique revealed that despite fragmentation and overexploitation, this species maintains a relatively high level of genetic diversity supporting the existence of random mating. Two genetic groups were found corresponding to the northern (LM and TR) and southern (FC) areas. The study suggests that, if local extinctions occurred in Mozambique, the pepper-bark tree persisted in sufficient numbers to retain a large proportion of genetic diversity. Management plans should concentrate on maintaining this high level of genetic variability through both in and ex-situ conservation actions. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Senkoro, Annae Maria
- Date: 2022-04-08
- Subjects: Ethnobotany Mozambique , Conservation biology Mozambique , Canellaceae Habitat Mozambique , Canellaceae Genetics , Warburgia salutaris Habitat Mozambique , Warburgia salutaris Genetics , Endangered plants Mozambique , Biogeography Climatic factors Mozambique , Traditional medicine Mozambique , Traditional ecological knowledge Mozambique
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232967 , vital:50042 , DOI 10.21504/10962/232967
- Description: Warburgia salutaris, locally known as “chibaha” (Ronga, Tsonga), “isiBhaha” (Zulu) and “siBhaha” (Siswati), is one of the most highly-valued medicinal plant species in southern Africa. Its bark has long been employed to treat bacterial and fungal infections, and it is often a front line herbal treatment for malaria. The species is popular in rural and urban areas due to its lower price compared to commercial pharmaceuticals and because of its long-standing spiritual and symbolic significance. Consequently, W. salutaris is threatened in Malawi, South Africa and Swaziland and is believed to be extincted in the wild in Zimbabwe. In Mozambique, where the tree is confined to the southern part of the country, it is considered vulnerable due to high local demand and cross-border export. Although there is limited research, further work is urgently needed to provide the basis for options and strategies to achieve desired outcomes. This study aimed to explore different approaches for the conservation of W. salutaris in the Lebombo Mountains (LM), the Tembe River (TR) and the Futi Corridor (FC) areas, in southern Mozambique. For this, potential distribution, socio cultural factors that influenced sustainable management of the species, demography, harvest impact, genetic diversity and population differentiation were considered. The kuenm package in R, 2 846 occurrence and 11 environmental data were used to model the potential current and future distribution in 2050 and 2070 using four general circulation models (CESM1(BGC), ACCESS1.3, FIO-ESM and IPSL-CM5A-MR) under representative concentration pathways (RCPs) 4.5 and 8.5. The extent of occurrence (EOO) and habitat suitability (HS) were also determined. Stratified random semi-structured interviews with 182 heads of households were carried out to explore cultural and socio incentives of use, compared knowledge distribution, determine local management practices and explore local ecological knowledge related to the species in the three study areas. In addition, 17 focus group discussion were conducted to clarify issues raised during household interviews. One hundred and twenty four quadrants were used to determine the abundance and population structure. The Simpson index of dominance, permutation index and quotient between consecutive classes were used to assess population stability, and an eight point scale was used to evaluate the extent of bark damages. Genomic deoxyribonucleic acid (gDNA) (n=48) was used to assessed genetic diversity and population structure through the newly developed single sequence repeats (SSR) molecular markers. Model selected was statistical significant for prediction of potential distribution of W. salutaris in southern Mozambique (partial ROC =0.00, omission rate = 0.04 and delta AICc = 0.00). The current environmental conditions mostly explained by climatic predictor, indicated in general, the potential distribution on areas of occurrence observed during the field work in southern Mozambique. Future project suggested an increase of climatic suitable areas in all the general circulation models in both conservative and pessimistic climatic scenarios (RCPs 4.5 and 8.5, respectively) in 2050 and 2070, and consequently the increase of HS and the EOO. Results of this work suggests W. salutaris would not extinct at least in the coming 50 years due to climate change but other threats such as overexploitation of the species need to be addressed. With increase of climatic suitable areas, conservation and management of this species could focus on reintroduction and cultivation for recovery of the species, with the help of time. W. salutaris was used for medicinal purposes to treat 12 health problems, with the bark being the most commonly used part (92% of informants). Knowledge of the species uses differed significantly between the three study areas but not with respondent gender or age. Informants also mentioned a considerable number of alternative species of W. salutaris (37 species in LM, 33 species in TR and 17 species in FC). Local ecological knowledge on the ecological niche of the species also varied substantial in the three areas with both types of knowledge generally higher in the Tembe River area. Local management practises were revealed mostly on harvesting through vertical bark stripping cited by 100% of informants in TR, 61.6% FC and 51.7 LM (71% of all informants). Yet most (64.3% of all informants, corresponding to 98.4% in TR, 51.7% in Fc and 41.7% LM) used non-traditional harvesting tools (machete) bark removal. For sustainable use of the species, consideration should be given to combined conservation strategies such as the use of alternative species with the same application, substitution of bark by leaves, and increases in alternative sources of plant material through cultivation. The densities of alive stems were not statistically different in the three areas but was higher in LM (mean of 4500.3±9209.8 stems/ha). Equally the mean densities of recruits (diameter ≤2 cm) were not considerable different but was higher in the FC (3296.8±9116.7 stems/ha). The regression analyses for the three study area revealed negative slopes, indicating more recruits and fewer individuals in larger classes. The Simpson indexes of dominance, permutation indexes and quotients between the consecutive size classes suggested some levels of population instability in the three areas. Harvesting took place in the eight point scale, all size classes were harvested but preference was higher on intermediate (15.1-20 cm) or larger (>20 cm) size classes in all the study areas but gatherers avoided harvesting bark from recruits. Although the mean densities of harvested stem was not significant this work indicated higher levels of stem destruction in FC. Harvested dead stems ware significant in the three areas and FC had the higher of (39.5±85.9 stems/ha) compared to 7.6±19.1 and 2.1±4.3 in TR and LM, respectively. Equally, the density of physiologically stressed stems differed substantially in the three areas with higher in FC 20.5± 75.5 stems/ha compared to 18.7±82.9 stems/ha in TR and 3.8±11.8 stems/ha in LM. This results suggests implementation of protection measures such as the inclusion of the species in the national CITES list to regulated cross-border trade and strengthening of the law enforcement. Genetic diversity, structure and gene flow in the exiting populations of southern Mozambique revealed that despite fragmentation and overexploitation, this species maintains a relatively high level of genetic diversity supporting the existence of random mating. Two genetic groups were found corresponding to the northern (LM and TR) and southern (FC) areas. The study suggests that, if local extinctions occurred in Mozambique, the pepper-bark tree persisted in sufficient numbers to retain a large proportion of genetic diversity. Management plans should concentrate on maintaining this high level of genetic variability through both in and ex-situ conservation actions. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-04-08
Neutral winds and tides over South Africa
- Authors: Ojo, Taiwo Theophilus
- Date: 2022-04-08
- Subjects: Atmospheric tides , Ionosondes , Fabry-Perot interferometers , Thermospheric winds , Servomechanisms , Climatology , Neutral winds , Horizontal Wind Model (HWM)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232459 , vital:49993 , DOI 10.21504/10962/232459
- Description: This thesis presents the first results of a climatology of nighttime thermospheric neutral winds between February 2018 and January 2019 measured by a Fabry-Perot interferometer (FPI) in Sutherland, South Africa (32.2°S, 20.48°E; geomagnetic latitude: 40.7°S). This FPI measures the nighttime oxygen airglow emission at 630.0 nm, which has a peak intensity at an altitude of roughly 250 km. The performance of the Horizontal Wind Model (HWM14) was evaluated by comparing results from HWM14 with the FPI measurements. The results showed that the model had a better agreement with the measurements for meridional component compared to the zonal component. In addition, the HWM14 zonal wind consistently peaked several hours (~3 h) prior to the measured wind, creating what looks like a phase shift compared to the measured wind. An investigation of this apparent phase shift revealed it to be a consequence of a difference in phase shift of the terdiunal tide. Since ionosondes are more prolific with wider temporal and spatial coverage than FPIs, nighttime meridional winds aligned to the magnetic meridian were inferred from the peak height (hmF2) of ionospheric data taken from South Africa ionosonde network using the servo model during February 2018-June 2019. These were compared with FPI measured meridional wind and benchmarked with HWM14 and Magnetic mEridional NeuTrAl Thermospheric (MENTAT) model. The amplitudes and trends of the calculated meridional winds across all four ionosonde stations agreed relatively well with the observed data, especially during the summer months. Furthermore, the results confirmed that the ionosonde station located closest to the FPI, i.e. Hermanus station, had better agreement with measurements compared to the stations located at further distances. The extraction and analysis of atmospheric tides, namely the diurnal, semidiurnal, terdiurnal and 6-hour components from the FPI as well as the long-term tidal winds variations from the thermospheric wind measurements were investigated. The results showed that the semidiurnal peak mostly had the highest peak across all the months, indicating that the semidiurnal tides dominate the dynamic structure of the upper mesosphere at midlatitudes, consistent with previous observation over midlatitudes. Futhermore, the signature of the diurnal tide in the meridional (zonal) wind was stronger in winter (summer) and weaker in summer (winter). Also, semidiurnal tide didn't show any trend with season, while the terdiurnal tide was dominant in summer (zonal) and winter (meridional). Lastly, the 6 hour tide was detected intermittently during the period of the study and had the weakest signature (i.e. lowest amplitudes). , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Ojo, Taiwo Theophilus
- Date: 2022-04-08
- Subjects: Atmospheric tides , Ionosondes , Fabry-Perot interferometers , Thermospheric winds , Servomechanisms , Climatology , Neutral winds , Horizontal Wind Model (HWM)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232459 , vital:49993 , DOI 10.21504/10962/232459
- Description: This thesis presents the first results of a climatology of nighttime thermospheric neutral winds between February 2018 and January 2019 measured by a Fabry-Perot interferometer (FPI) in Sutherland, South Africa (32.2°S, 20.48°E; geomagnetic latitude: 40.7°S). This FPI measures the nighttime oxygen airglow emission at 630.0 nm, which has a peak intensity at an altitude of roughly 250 km. The performance of the Horizontal Wind Model (HWM14) was evaluated by comparing results from HWM14 with the FPI measurements. The results showed that the model had a better agreement with the measurements for meridional component compared to the zonal component. In addition, the HWM14 zonal wind consistently peaked several hours (~3 h) prior to the measured wind, creating what looks like a phase shift compared to the measured wind. An investigation of this apparent phase shift revealed it to be a consequence of a difference in phase shift of the terdiunal tide. Since ionosondes are more prolific with wider temporal and spatial coverage than FPIs, nighttime meridional winds aligned to the magnetic meridian were inferred from the peak height (hmF2) of ionospheric data taken from South Africa ionosonde network using the servo model during February 2018-June 2019. These were compared with FPI measured meridional wind and benchmarked with HWM14 and Magnetic mEridional NeuTrAl Thermospheric (MENTAT) model. The amplitudes and trends of the calculated meridional winds across all four ionosonde stations agreed relatively well with the observed data, especially during the summer months. Furthermore, the results confirmed that the ionosonde station located closest to the FPI, i.e. Hermanus station, had better agreement with measurements compared to the stations located at further distances. The extraction and analysis of atmospheric tides, namely the diurnal, semidiurnal, terdiurnal and 6-hour components from the FPI as well as the long-term tidal winds variations from the thermospheric wind measurements were investigated. The results showed that the semidiurnal peak mostly had the highest peak across all the months, indicating that the semidiurnal tides dominate the dynamic structure of the upper mesosphere at midlatitudes, consistent with previous observation over midlatitudes. Futhermore, the signature of the diurnal tide in the meridional (zonal) wind was stronger in winter (summer) and weaker in summer (winter). Also, semidiurnal tide didn't show any trend with season, while the terdiurnal tide was dominant in summer (zonal) and winter (meridional). Lastly, the 6 hour tide was detected intermittently during the period of the study and had the weakest signature (i.e. lowest amplitudes). , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-08
Sequence, structure, dynamics, and substrate specificity analyses of bacterial Glycoside Hydrolase 1 enzymes from several activities
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
The characterization of GTP Cyclohydrolase I and 6-Pyruvoyl Tetrahydropterin Synthase enzymes as potential anti-malarial drug targets
- Khairallah, Afrah Yousif Huseein
- Authors: Khairallah, Afrah Yousif Huseein
- Date: 2022-04-08
- Subjects: Antimalarials , Plasmodium falciparum , Malaria Chemotherapy , Malaria Africa , Drug resistance , Drug development , Molecular dynamics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233784 , vital:50127 , DOI 10.21504/10962/233784
- Description: Malaria remains a public health problem and a high burden of disease, especially in developing countries. The unicellular protozoan malaria parasite of the genus Plasmodium infects about a quarter of a billion people annually, with an estimated 409 000 death cases. The majority of malaria cases occurred in Africa; hence, the region is regarded as endemic for malaria. Global efforts to eradicate the disease led to a decrease in morbidity and mortality rates. However, an enormous burden of malaria infection remains, and it cannot go unnoticed. Countries with limited resources are more affected by the disease, mainly on its public health and socio-economic development, due to many factors besides malaria itself, such as lack of access to adequate, affordable treatments and preventative regimes. Furthermore, the current antimalarial drugs are losing their efficacy because of parasite drug resistance. The emerged drug resistance has reduced the drug efficacy in clearing the parasite from the host system, causing prolonged illness and a higher risk of death. Therefore, the emerged antimalarial drug resistance has hindered the global efforts for malaria control and elimination and established an urgent need for new treatment strategies. When the resistance against classical antimalarial drugs emerged, the class of antifolate antimalarial medicines became the most common alternative. The antifolate antimalarial drugs target the malaria parasite de novo folate biosynthesis pathway by limiting folate derivates, which are essential for the parasite cell growth and survival. Yet again, the malaria parasite developed resistance against the available antifolate drugs, rendering the drugs ineffective in many cases. Given the previous success in targeting the malaria parasite de novo folate biosynthesis pathway, alternative enzymes within this pathway stand as good targets and can be explored to develop new antifolate drugs with novel mechanisms of action. The primary focus of this thesis is to contribute to the existing and growing knowledge of antimalarial drug discovery. The study aims to characterise the malaria parasite de novo folate synthesis pathway enzymes guanosine-5'-triphosphate (GTP) cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS) as alternative drug targets for malaria treatment by using computational approaches. Further, discover new allosteric drug targeting sites within the two enzymes' 3D structures for future drug design and discovery. Sequence and structural analysis were carried out to characterise and pinpoint the two enzymes' unique sequence and structure-based features. From the analyses, key sequence and structure differences were identified between the malaria parasite enzymes relative to their human homolog; the identified sites can aid significantly in designing and developing new antimalarial antifolate drugs with good selectivity toward the parasites’ enzymes. GCH1 and PTPS contain a catalytically essential metal ion in their active site; therefore, force field parameters were needed to study their active sites accurately during all-atom molecular dynamic simulations (MD). The force field parameters were derived through quantum mechanics potential energy surface scans of the metals bonded terms and evaluated via all-atom MD simulations. Proteins structural dynamics is imperative for many biological processes; thus, it is essential to consider the structural dynamics of proteins whilst understanding their function. In this regard, the normal mode analysis (NMA) approach based on the elastic network model (ENM) was employed to study the intrinsic dynamics and conformations changes of GCH1 and PTPS enzymes. The NMA disclosed essential structural information about the protein’s intrinsic dynamics and mechanism of allosteric modulation of their binding properties, further highlighting regions that govern their conformational changes. The analysis also disclosed hotspot residues that are crucial for the proteins' fold stability and function. The NMA was further combined with sequence motif results and showed that conserved residues of GCH1 and PTPS were located within the identified key structural sites modulating the proteins' conformational rearrangement. The characterized structural features and hotspot residues were regarded as potential allosteric sites of important value for the design and development of allosteric drugs. Both GCH1 and PTPS enzymes have never been targeted before and can provide an excellent opportunity to overcome the antimalarial antifolate drug resistance problem. The data presented in this thesis contribute to the understanding of the sequence, structure, and global dynamics of both GCH1 and PTPS, further disclose potential allosteric drug targeting sites and unique structural features of both enzymes that can establish a solid starting point for drug design and development of new antimalarial drugs of a novel mechanism of actions. Lastly, the reported force field parameters will be of value for MD simulations for future in-silico drug discovery studies involving the two enzymes and other enzymes with the same Zn2+ binding motifs and coordination environments. The impact of this research can facilitate the discovery of new effective antimalarial medicines with novel mechanisms of action. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Khairallah, Afrah Yousif Huseein
- Date: 2022-04-08
- Subjects: Antimalarials , Plasmodium falciparum , Malaria Chemotherapy , Malaria Africa , Drug resistance , Drug development , Molecular dynamics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233784 , vital:50127 , DOI 10.21504/10962/233784
- Description: Malaria remains a public health problem and a high burden of disease, especially in developing countries. The unicellular protozoan malaria parasite of the genus Plasmodium infects about a quarter of a billion people annually, with an estimated 409 000 death cases. The majority of malaria cases occurred in Africa; hence, the region is regarded as endemic for malaria. Global efforts to eradicate the disease led to a decrease in morbidity and mortality rates. However, an enormous burden of malaria infection remains, and it cannot go unnoticed. Countries with limited resources are more affected by the disease, mainly on its public health and socio-economic development, due to many factors besides malaria itself, such as lack of access to adequate, affordable treatments and preventative regimes. Furthermore, the current antimalarial drugs are losing their efficacy because of parasite drug resistance. The emerged drug resistance has reduced the drug efficacy in clearing the parasite from the host system, causing prolonged illness and a higher risk of death. Therefore, the emerged antimalarial drug resistance has hindered the global efforts for malaria control and elimination and established an urgent need for new treatment strategies. When the resistance against classical antimalarial drugs emerged, the class of antifolate antimalarial medicines became the most common alternative. The antifolate antimalarial drugs target the malaria parasite de novo folate biosynthesis pathway by limiting folate derivates, which are essential for the parasite cell growth and survival. Yet again, the malaria parasite developed resistance against the available antifolate drugs, rendering the drugs ineffective in many cases. Given the previous success in targeting the malaria parasite de novo folate biosynthesis pathway, alternative enzymes within this pathway stand as good targets and can be explored to develop new antifolate drugs with novel mechanisms of action. The primary focus of this thesis is to contribute to the existing and growing knowledge of antimalarial drug discovery. The study aims to characterise the malaria parasite de novo folate synthesis pathway enzymes guanosine-5'-triphosphate (GTP) cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS) as alternative drug targets for malaria treatment by using computational approaches. Further, discover new allosteric drug targeting sites within the two enzymes' 3D structures for future drug design and discovery. Sequence and structural analysis were carried out to characterise and pinpoint the two enzymes' unique sequence and structure-based features. From the analyses, key sequence and structure differences were identified between the malaria parasite enzymes relative to their human homolog; the identified sites can aid significantly in designing and developing new antimalarial antifolate drugs with good selectivity toward the parasites’ enzymes. GCH1 and PTPS contain a catalytically essential metal ion in their active site; therefore, force field parameters were needed to study their active sites accurately during all-atom molecular dynamic simulations (MD). The force field parameters were derived through quantum mechanics potential energy surface scans of the metals bonded terms and evaluated via all-atom MD simulations. Proteins structural dynamics is imperative for many biological processes; thus, it is essential to consider the structural dynamics of proteins whilst understanding their function. In this regard, the normal mode analysis (NMA) approach based on the elastic network model (ENM) was employed to study the intrinsic dynamics and conformations changes of GCH1 and PTPS enzymes. The NMA disclosed essential structural information about the protein’s intrinsic dynamics and mechanism of allosteric modulation of their binding properties, further highlighting regions that govern their conformational changes. The analysis also disclosed hotspot residues that are crucial for the proteins' fold stability and function. The NMA was further combined with sequence motif results and showed that conserved residues of GCH1 and PTPS were located within the identified key structural sites modulating the proteins' conformational rearrangement. The characterized structural features and hotspot residues were regarded as potential allosteric sites of important value for the design and development of allosteric drugs. Both GCH1 and PTPS enzymes have never been targeted before and can provide an excellent opportunity to overcome the antimalarial antifolate drug resistance problem. The data presented in this thesis contribute to the understanding of the sequence, structure, and global dynamics of both GCH1 and PTPS, further disclose potential allosteric drug targeting sites and unique structural features of both enzymes that can establish a solid starting point for drug design and development of new antimalarial drugs of a novel mechanism of actions. Lastly, the reported force field parameters will be of value for MD simulations for future in-silico drug discovery studies involving the two enzymes and other enzymes with the same Zn2+ binding motifs and coordination environments. The impact of this research can facilitate the discovery of new effective antimalarial medicines with novel mechanisms of action. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
The systematic assembly of prostate specific antigen electrochemical sensors based on asymmetric Co(II) phthalocyanines, graphitic quantum dots and an aptamer
- Authors: Nxele, Siphesihle Robin
- Date: 2022-04-08
- Subjects: Prostate-specific antigen , Electrochemical sensors , Phthalocyanines , Quantum dots , Co(II) phthalocyanines , Aptamer
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232893 , vital:50035 , DOI 10.21504/10962/232893
- Description: The need for low-cost, efficient and simple diagnostic tools has led to more research going into this subject, with the aim of making such medical devices more accessible where they are needed. This has led to more researchers developing point-of-care devices for this purpose worldwide, by sensor fabrication. This thesis focuses on electrochemical sensor development for the early diagnosis of prostate cancer. It is common knowledge that prostate cancer is one of the most prevalent carcinomas that have claimed lives due to late diagnosis where even the most invasive treatments have failed. For this reason, development of early detection devices that can even be used in the comfort of home is necessary and quite crucial. Electrochemical sensors have gained much attention due to their ease of fabrication, cost effectiveness, simplicity, ease of use and high efficiency. Using nanocomposites as modifiers has also become popular as they provide greater stability and improve detection limits when used together with biomolecules. With that said, the work reported herein has combined nanocomposites of graphenebased quantum dots, gold nanoparticles, phthalocyanines and an aptamer in order to fabricate aptasensors for the electrochemical detection of prostate cancer biomarker. The aptamer is specifically designed to bind to the biomarker, and the nanocomposites are expected to enhance current output thus lowering detection limits and increasing stability and efficiency. Reproducible results are also expected. Prior to the detection of the prostate cancer biomarker, the quantum dots-phthalocyanine nanohybrids were used to detect L-cysteine, which is an amino acid, in order to verify the synergistic effects as electrode modifiers that lead to the enhancement of current output. This increase in current output is then v exploited for the improvement of aptasensor functionality upon incorporation of the aptamer, for the detection of prostate specific antigen. The research in this thesis has been carried out with the intention of contributing to the world of medical research, more so because of the ever-increasing need for medical care to become accessible to all and not only to those who can afford expensive technologies and treatments. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Nxele, Siphesihle Robin
- Date: 2022-04-08
- Subjects: Prostate-specific antigen , Electrochemical sensors , Phthalocyanines , Quantum dots , Co(II) phthalocyanines , Aptamer
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232893 , vital:50035 , DOI 10.21504/10962/232893
- Description: The need for low-cost, efficient and simple diagnostic tools has led to more research going into this subject, with the aim of making such medical devices more accessible where they are needed. This has led to more researchers developing point-of-care devices for this purpose worldwide, by sensor fabrication. This thesis focuses on electrochemical sensor development for the early diagnosis of prostate cancer. It is common knowledge that prostate cancer is one of the most prevalent carcinomas that have claimed lives due to late diagnosis where even the most invasive treatments have failed. For this reason, development of early detection devices that can even be used in the comfort of home is necessary and quite crucial. Electrochemical sensors have gained much attention due to their ease of fabrication, cost effectiveness, simplicity, ease of use and high efficiency. Using nanocomposites as modifiers has also become popular as they provide greater stability and improve detection limits when used together with biomolecules. With that said, the work reported herein has combined nanocomposites of graphenebased quantum dots, gold nanoparticles, phthalocyanines and an aptamer in order to fabricate aptasensors for the electrochemical detection of prostate cancer biomarker. The aptamer is specifically designed to bind to the biomarker, and the nanocomposites are expected to enhance current output thus lowering detection limits and increasing stability and efficiency. Reproducible results are also expected. Prior to the detection of the prostate cancer biomarker, the quantum dots-phthalocyanine nanohybrids were used to detect L-cysteine, which is an amino acid, in order to verify the synergistic effects as electrode modifiers that lead to the enhancement of current output. This increase in current output is then v exploited for the improvement of aptasensor functionality upon incorporation of the aptamer, for the detection of prostate specific antigen. The research in this thesis has been carried out with the intention of contributing to the world of medical research, more so because of the ever-increasing need for medical care to become accessible to all and not only to those who can afford expensive technologies and treatments. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-04-08
An investigation of traveling ionospheric disturbances (TIDs) in the SANAE HF radar data
- Authors: Atilaw, Tsige Yared
- Date: 2022-04-07
- Subjects: Ionospheric storms Antarctica , Radar Antarctica , Range time-intensity (RTI) , South African National Antarctic Expedition (SANAE) , Super Dual Auroral Radar Network (SuperDARN)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232377 , vital:49986 , DOI 10.21504/10962/232377
- Description: This thesis aims to study the characteristics of traveling ionospheric disturbances (TIDs) as identified in the radar data of the South African National Antarctic Expedition (SANAE) Super Dual Auroral Radar Network (SuperDARN) radar located in Antarctica. For this project, 22 TIDs were identified from visual inspection of range time-intensity (RTI) plots of backscattered power and Doppler velocity parameters of the SANAE radar between 2005âAS2015. These events were studied to determine their characteristics and driving mechanisms. Where good quality data were available, the SANAE HF radar data were supplemented by Halley radar data, which has large area of overlapping field of view (FOV) with the SANAE radar, and also by GPS TEC data. This provided a multi-instrument data analysis of some TID events. Different spectral analysis methods, namely the multitaper method (MTM), Fast Fourier transform (FFT) and the Lomb-Scargle periodogram were used to obtain spectral information of the observed waves. The advantage of using multiple windowing in MTM over the traditional windowing method was illustrated using one of the TID events. In addition, the analytic signal of the wave from the MTM method was used to estimate the instantaneous phase velocity and propagation azimuth of the wave, which was able to track the change in the characteristics of the medium-scale TID (MSTID) efficiently throughout the duration of the event. This is a clear advantage over other windowing techniques. The energy contribution by this MSTID through Joule heating was estimated over the region where spectral analysis of both SANAE and Halley data showed it to be present. The majority of the TIDs (65.4%) could be classified as MSTIDs with periods of 20–60 minutes, velocities of 50–333 ms1 and wavelengths of 129–833 km. The TID occurrence rate was high around the March equinox with 12 out of the 16 event days being during March–May. March had a particularly high number of occurrences of TIDs (46%). The majority of the TIDs observed during this month propagated northward or southeastward. In terms of prevailing geomagnetic conditions, 6 out of 16 event days were geomagnetically quiet, while 10 occurred during geomagnetic storms and substorms. During quiet conditions, TIDs could be linked to Es and polarised electric fields in 2 of these events. The other quiet time events could not be related to Es instability and polarised electric field either because their exact propagation direction could not be determined or data quality from the Es region scatter was too poor to perform spectral analysis. The storm-/substorm-related TIDs are possibly generated through Joule heating, the Lorentz force and energetic particle precipitation. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-07
- Authors: Atilaw, Tsige Yared
- Date: 2022-04-07
- Subjects: Ionospheric storms Antarctica , Radar Antarctica , Range time-intensity (RTI) , South African National Antarctic Expedition (SANAE) , Super Dual Auroral Radar Network (SuperDARN)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232377 , vital:49986 , DOI 10.21504/10962/232377
- Description: This thesis aims to study the characteristics of traveling ionospheric disturbances (TIDs) as identified in the radar data of the South African National Antarctic Expedition (SANAE) Super Dual Auroral Radar Network (SuperDARN) radar located in Antarctica. For this project, 22 TIDs were identified from visual inspection of range time-intensity (RTI) plots of backscattered power and Doppler velocity parameters of the SANAE radar between 2005âAS2015. These events were studied to determine their characteristics and driving mechanisms. Where good quality data were available, the SANAE HF radar data were supplemented by Halley radar data, which has large area of overlapping field of view (FOV) with the SANAE radar, and also by GPS TEC data. This provided a multi-instrument data analysis of some TID events. Different spectral analysis methods, namely the multitaper method (MTM), Fast Fourier transform (FFT) and the Lomb-Scargle periodogram were used to obtain spectral information of the observed waves. The advantage of using multiple windowing in MTM over the traditional windowing method was illustrated using one of the TID events. In addition, the analytic signal of the wave from the MTM method was used to estimate the instantaneous phase velocity and propagation azimuth of the wave, which was able to track the change in the characteristics of the medium-scale TID (MSTID) efficiently throughout the duration of the event. This is a clear advantage over other windowing techniques. The energy contribution by this MSTID through Joule heating was estimated over the region where spectral analysis of both SANAE and Halley data showed it to be present. The majority of the TIDs (65.4%) could be classified as MSTIDs with periods of 20–60 minutes, velocities of 50–333 ms1 and wavelengths of 129–833 km. The TID occurrence rate was high around the March equinox with 12 out of the 16 event days being during March–May. March had a particularly high number of occurrences of TIDs (46%). The majority of the TIDs observed during this month propagated northward or southeastward. In terms of prevailing geomagnetic conditions, 6 out of 16 event days were geomagnetically quiet, while 10 occurred during geomagnetic storms and substorms. During quiet conditions, TIDs could be linked to Es and polarised electric fields in 2 of these events. The other quiet time events could not be related to Es instability and polarised electric field either because their exact propagation direction could not be determined or data quality from the Es region scatter was too poor to perform spectral analysis. The storm-/substorm-related TIDs are possibly generated through Joule heating, the Lorentz force and energetic particle precipitation. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Date Issued: 2022-04-07
Exploring structures and beliefs underlying textbook praxis in German foreign language courses at a South African university – a social realist perspective
- Authors: Engelbrecht, Natasha
- Date: 2022-04-07
- Subjects: German language Study and teaching (Higher) English speakers , Curriculum change South Africa , German language Textbooks History and criticism , Common European Framework of Reference for Languages (Project) , Decolonization South Africa , Educational change South Africa , Social realism
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232657 , vital:50011 , DOI https://doi.org/10.21504/10962/232657
- Description: Commercial textbooks, aligned with the Common European Framework of Reference for Languages (CEFR), are prescribed in almost all undergraduate GFL courses offered at South African universities. Although providing practical relevance and quality assurance, the CEFR-level descriptors were developed for the European context. The projected relevance and appropriateness of teaching materials presently implemented in German curricula in South African higher education have been determined in Germany, not for local contexts, but for learners vaguely described as “Anfänger” (Evans, et al., 2012, p. 8) and “Erwachsene und Jugendliche ab 16 Jahren” (Hueber, 2019, p. 11), often with a focus on learning for prospective German immigrants or for the use in refugee- or immigrant integration courses. However, the textbook occupies a central position in the GFL course because of the structured grammar progression that it lends to the curriculum. The variety of resources available to lecturers (tests, worksheets, online learning platform) and students (exercises, English-German glossary, English grammar explanations) is also an asset to GFL courses. Calls for the transformation and decolonisation of higher education have prompted academic disciplines to re-evaluate the common-sense assumptions which underpin knowledge practices in their curriculum. Following a social realist perspective and an exploratory case-study approach, this study presents a critical analysis of the textbook prescribed in the German Studies 1 course at Rhodes University and student experiences of the textbook to disentangle the complex relations which cause textbook praxis and lay bare power structures and tensions in the system. , Thesis (PhD) -- Humanities, School of Languages and Literatures, 2022
- Full Text:
- Date Issued: 2022-04-07
- Authors: Engelbrecht, Natasha
- Date: 2022-04-07
- Subjects: German language Study and teaching (Higher) English speakers , Curriculum change South Africa , German language Textbooks History and criticism , Common European Framework of Reference for Languages (Project) , Decolonization South Africa , Educational change South Africa , Social realism
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232657 , vital:50011 , DOI https://doi.org/10.21504/10962/232657
- Description: Commercial textbooks, aligned with the Common European Framework of Reference for Languages (CEFR), are prescribed in almost all undergraduate GFL courses offered at South African universities. Although providing practical relevance and quality assurance, the CEFR-level descriptors were developed for the European context. The projected relevance and appropriateness of teaching materials presently implemented in German curricula in South African higher education have been determined in Germany, not for local contexts, but for learners vaguely described as “Anfänger” (Evans, et al., 2012, p. 8) and “Erwachsene und Jugendliche ab 16 Jahren” (Hueber, 2019, p. 11), often with a focus on learning for prospective German immigrants or for the use in refugee- or immigrant integration courses. However, the textbook occupies a central position in the GFL course because of the structured grammar progression that it lends to the curriculum. The variety of resources available to lecturers (tests, worksheets, online learning platform) and students (exercises, English-German glossary, English grammar explanations) is also an asset to GFL courses. Calls for the transformation and decolonisation of higher education have prompted academic disciplines to re-evaluate the common-sense assumptions which underpin knowledge practices in their curriculum. Following a social realist perspective and an exploratory case-study approach, this study presents a critical analysis of the textbook prescribed in the German Studies 1 course at Rhodes University and student experiences of the textbook to disentangle the complex relations which cause textbook praxis and lay bare power structures and tensions in the system. , Thesis (PhD) -- Humanities, School of Languages and Literatures, 2022
- Full Text:
- Date Issued: 2022-04-07
Institutional innovations for improved water security in smallholder irrigation schemes in KwaZulu-Natal and Eastern Cape Provinces, South Africa
- Authors: Phakathi, Sandile
- Date: 2022-04-06
- Subjects: Water security South Africa , Rural development projects South Africa , Institutional cooperation South Africa , Irrigation farming South Africa , Food security South Africa , Agricultural innovations South Africa , Irrigation Technological innovations South Africa , Smallholder irrigation schemes
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232341 , vital:49983 , DOI 10.21504/10962/232341
- Description: Smallholder irrigation schemes are regarded as a key strategy to eliminate poverty and increase food security in rural areas in South Africa. While the South African government has invested heavily in rural development schemes, most irrigation schemes face a myriad of challenges, including deficient infrastructure, weak institutional arrangements and water insecurity. Weak institutions have been identified as a major bottleneck in the performance of smallholder irrigation schemes in developing countries, including South Africa. Two main reasons have been identified for this challenge. Firstly, the agency of the irrigators was ignored during the design of the schemes. Treating farmers as passive rather than active agents resulted in institutional arrangements that were not context-specific, as well as weak farmer commitment to the ownership and management of the schemes, leading to system breakdown. Despite being noble in intention or design, institutions designed by outsiders often fail due to a lack of legitimacy. Secondly, institutions have failed to evolve to cope with dynamic challenges and opportunities in the sector. Stability over a reasonable period is required for institutions to effectively perform their crucial role of establishing reasonable expectations in dealings among people. Institutional innovations are required to keep up with the changing nature of development. In particular, farmer-led institutional innovations have been touted as key to improving the management of water resources in irrigation schemes. Farmer-led institutional innovation refers to a process, in which farmers themselves initiate, establish, and improve institutions based on their context-specific challenges or opportunities. Farmers’ groups are regarded as an important institutional arrangement to reduce transaction costs, improve social networks, and increase livelihood outcomes. However, little is known about the internal dynamics of these farmer groups, how they operate, and whether or not they are inclusive and innovative, as well as what makes certain groups more successful than others. Furthermore, there is a paucity of research on whether these farmer groups embrace institutional innovations to improve water security and strengthen their design principles that are crucial for collective action. It is against this background that this study aimed to examine the internal group dynamics within the farmer groups; determine whether smallholder farmers are capable of implementing institutional innovations that are novel, useful and legitimate; determine the nature of these innovations (incremental or radical) and their role in improving water security. The main theories that underpinned the study were induced institutional innovation theory, collective action theory, random utility theory and Ostrom’s eight design principles. Multistage sampling was used to collect data from 28 farmer groups and 401 irrigators in smallholder irrigation schemes in KwaZulu-Natal (Tugela Ferry and Mooi River) and the Eastern Cape (Qamata and Zanyokwe). Data were gathered by means of focus group discussions, key informant interviews and household surveys. Several empirical tools were employed to analyse the data (descriptive statistics, thematic analysis, logit model, propensity score matching, PCA and OLS). The study found that group membership was associated with higher levels of water access, adoption of inorganic fertiliser, incomes and assets. Group members had an additional four days’ access to water in a month and applied at least 130 kg/ha more inorganic fertiliser than non-group members. Group members also had a higher household income per capita and more assets than non-group members. However, the results revealed a heterogeneous effect among group members, with the benefits varying according to members’ socio-economic characteristics as well as internal group dynamics. The results suggest that organising farmers into groups should be promoted to improve farmers’ access to productive assets such as water, technology adoption and welfare outcomes. However, the study findings also indicate that smaller groups should be promoted, programmes targeted at empowering women should be prioritised, and that it is imperative to invest in improving farmers’ human capital through various training initiatives. The results indicated that farmers could develop and implement institutional innovations that are novel, useful and legitimate. Of the 28 groups, 21 (75%) had implemented institutional innovations in the past three years. Examples of innovations include, among others, the introduction of a secret voting system to improve marginalised people’s participation in decision-making processes, designing daily rotation rosters to reduce conflict, using an attendance register for participation in group activities, and rewarding members according to their participation levels. Most of these innovations were designed to improve the graduated sanction mechanism (22.2%), enhance the penalty system for non-compliance; improve collective action arrangements (27.8%); monitor attendance of group meetings (18.5%); democratise decision making; and ensure equitable water distribution. However, they mainly focused on addressing challenges rather than exploiting opportunities and were largely incremental (94%), involving an adjustment or reinterpretation of rules and regulations. Furthermore, the innovative groups were small in size and were dominated by male farmers. Based on these results, it is recommended that the government should build on the irrigators’ agency to improve the effectiveness and legitimacy of institutional arrangements in irrigation schemes. The findings also suggest that small groups should be actively promoted, while tailored training should be offered based on the groups’ specific needs to improve institutional innovations in the smallholder irrigation sector in South Africa. A positive association was established between belonging to an innovative group and water security, highlighting the importance of institutional innovations in water security. The propensity score matching indicated that water secure irrigators produced an additional 569-622 kg of maize and earned additional income of R2 037.81. The study’s findings suggest that organising farmers into groups is a promising strategy to improve farmers livelihoods and water security. The government and private donors should thus continue to promote the formation and organisation of farmers into groups. The innovative agency of the irrigators should be acknowledged and harnessed to strengthen institutional innovations. The focus should be on strengthening the institutions designed by farmers themselves, as these are locally contextualised and socially embedded, and hence legitimate. It is recommended that small groups should be actively promoted, while tailored training should be offered based on groups’ specific needs to improve institutional innovations in the smallholder irrigation sector in South Africa. , Thesis (PhD) -- Faculty of Commerce, Economics and Economic History, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Phakathi, Sandile
- Date: 2022-04-06
- Subjects: Water security South Africa , Rural development projects South Africa , Institutional cooperation South Africa , Irrigation farming South Africa , Food security South Africa , Agricultural innovations South Africa , Irrigation Technological innovations South Africa , Smallholder irrigation schemes
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232341 , vital:49983 , DOI 10.21504/10962/232341
- Description: Smallholder irrigation schemes are regarded as a key strategy to eliminate poverty and increase food security in rural areas in South Africa. While the South African government has invested heavily in rural development schemes, most irrigation schemes face a myriad of challenges, including deficient infrastructure, weak institutional arrangements and water insecurity. Weak institutions have been identified as a major bottleneck in the performance of smallholder irrigation schemes in developing countries, including South Africa. Two main reasons have been identified for this challenge. Firstly, the agency of the irrigators was ignored during the design of the schemes. Treating farmers as passive rather than active agents resulted in institutional arrangements that were not context-specific, as well as weak farmer commitment to the ownership and management of the schemes, leading to system breakdown. Despite being noble in intention or design, institutions designed by outsiders often fail due to a lack of legitimacy. Secondly, institutions have failed to evolve to cope with dynamic challenges and opportunities in the sector. Stability over a reasonable period is required for institutions to effectively perform their crucial role of establishing reasonable expectations in dealings among people. Institutional innovations are required to keep up with the changing nature of development. In particular, farmer-led institutional innovations have been touted as key to improving the management of water resources in irrigation schemes. Farmer-led institutional innovation refers to a process, in which farmers themselves initiate, establish, and improve institutions based on their context-specific challenges or opportunities. Farmers’ groups are regarded as an important institutional arrangement to reduce transaction costs, improve social networks, and increase livelihood outcomes. However, little is known about the internal dynamics of these farmer groups, how they operate, and whether or not they are inclusive and innovative, as well as what makes certain groups more successful than others. Furthermore, there is a paucity of research on whether these farmer groups embrace institutional innovations to improve water security and strengthen their design principles that are crucial for collective action. It is against this background that this study aimed to examine the internal group dynamics within the farmer groups; determine whether smallholder farmers are capable of implementing institutional innovations that are novel, useful and legitimate; determine the nature of these innovations (incremental or radical) and their role in improving water security. The main theories that underpinned the study were induced institutional innovation theory, collective action theory, random utility theory and Ostrom’s eight design principles. Multistage sampling was used to collect data from 28 farmer groups and 401 irrigators in smallholder irrigation schemes in KwaZulu-Natal (Tugela Ferry and Mooi River) and the Eastern Cape (Qamata and Zanyokwe). Data were gathered by means of focus group discussions, key informant interviews and household surveys. Several empirical tools were employed to analyse the data (descriptive statistics, thematic analysis, logit model, propensity score matching, PCA and OLS). The study found that group membership was associated with higher levels of water access, adoption of inorganic fertiliser, incomes and assets. Group members had an additional four days’ access to water in a month and applied at least 130 kg/ha more inorganic fertiliser than non-group members. Group members also had a higher household income per capita and more assets than non-group members. However, the results revealed a heterogeneous effect among group members, with the benefits varying according to members’ socio-economic characteristics as well as internal group dynamics. The results suggest that organising farmers into groups should be promoted to improve farmers’ access to productive assets such as water, technology adoption and welfare outcomes. However, the study findings also indicate that smaller groups should be promoted, programmes targeted at empowering women should be prioritised, and that it is imperative to invest in improving farmers’ human capital through various training initiatives. The results indicated that farmers could develop and implement institutional innovations that are novel, useful and legitimate. Of the 28 groups, 21 (75%) had implemented institutional innovations in the past three years. Examples of innovations include, among others, the introduction of a secret voting system to improve marginalised people’s participation in decision-making processes, designing daily rotation rosters to reduce conflict, using an attendance register for participation in group activities, and rewarding members according to their participation levels. Most of these innovations were designed to improve the graduated sanction mechanism (22.2%), enhance the penalty system for non-compliance; improve collective action arrangements (27.8%); monitor attendance of group meetings (18.5%); democratise decision making; and ensure equitable water distribution. However, they mainly focused on addressing challenges rather than exploiting opportunities and were largely incremental (94%), involving an adjustment or reinterpretation of rules and regulations. Furthermore, the innovative groups were small in size and were dominated by male farmers. Based on these results, it is recommended that the government should build on the irrigators’ agency to improve the effectiveness and legitimacy of institutional arrangements in irrigation schemes. The findings also suggest that small groups should be actively promoted, while tailored training should be offered based on the groups’ specific needs to improve institutional innovations in the smallholder irrigation sector in South Africa. A positive association was established between belonging to an innovative group and water security, highlighting the importance of institutional innovations in water security. The propensity score matching indicated that water secure irrigators produced an additional 569-622 kg of maize and earned additional income of R2 037.81. The study’s findings suggest that organising farmers into groups is a promising strategy to improve farmers livelihoods and water security. The government and private donors should thus continue to promote the formation and organisation of farmers into groups. The innovative agency of the irrigators should be acknowledged and harnessed to strengthen institutional innovations. The focus should be on strengthening the institutions designed by farmers themselves, as these are locally contextualised and socially embedded, and hence legitimate. It is recommended that small groups should be actively promoted, while tailored training should be offered based on groups’ specific needs to improve institutional innovations in the smallholder irrigation sector in South Africa. , Thesis (PhD) -- Faculty of Commerce, Economics and Economic History, 2022
- Full Text:
- Date Issued: 2022-04-06
Ownership and occupation contestations in South Africa: the case of state housing in Buffalo City Municipality, Eastern Cape
- Authors: Msindo, Esteri Makotore
- Date: 2022-04
- Subjects: Public housing South Africa Buffalo City , Squatters South Africa Buffalo City , Occupancy (Law) South Africa , Acquisition of property South Africa Buffalo City , Right of property South Africa Buffalo City , Sociology, Urban South Africa Buffalo City , Marginality, Social South Africa Buffalo City , Human rights South Africa , Acquisition of property Moral and ethical aspects South Africa Buffalo City , Urban poor South Africa Buffalo City Social conditions
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232790 , vital:50025 , DOI 10.21504/10962/232790
- Description: This thesis examines contestations around access to state-provided housing or simply state housing in South Africa, using a case study of two sites in Buffalo City Municipality, and with a particular focus on occupation without ownership through informal and illegal means. While the South African state, based on an official human rights discourse and regime, seeks to provide state housing to the urban poor, massive housing backlogs continue to exist within urban spaces. As a result, the urban poor turn to self-provisioning through the construction of informal settlements or backyard shacks, waiting at times indefinitely to be allocated a state house via the official housing waiting lists. To overcome this problem, some amongst the urban poor opt to circumvent the process by invading and illegally occupying state houses, leading to occupation without ownership. In doing so, they draw upon their own moral rights-claims to justify their actions. The thesis examines the multiple causes for occupation and ownership contestations in the two research sites as well as the different forms that these contestations take. The study is framed theoretically in terms of a sociology of human rights, identifying and analysing how moral claims to rights amongst ordinary people often come into conflict with a legal-institutional conception of rights adopted by the state. The study also draws on a diverse array of theorists whose work speaks to the manner in which ordinary citizens develop their own ways of acting contrary to state officialdom. Using interpretive sociology, the study considers the views and practices of those illegally occupying houses without ownership and those who feel victimised by these informal actions. It considers these intra-community dynamics in light of the machinations of local state powerholders at municipal level. As with interpretive sociology, then, the thesis privileges social realms of meanings, interpretations, experiences and practices of human agents. Informal state housing occupations in the Buffalo City Municipality are caused by a number of factors related to state incapacity, weak policies and poor planning, corruption, resource constraints and so on. The study vividly demonstrates the tensions arising and existing between the South African state’s legal human rights regime and locally-constructed moral-rights regimes amongst the urban poor. This tension is seen in the interrelated phenomena of ‘occupation without ownership’ and ‘ownership without occupation’, as the poor draw upon and use ordinary logics of rights for recourse. The thesis shows how diverse rights regimes lead to intra-community conflict, in particular along generational and racial lines. , Thesis (PhD) -- Humanities, Sociology, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Msindo, Esteri Makotore
- Date: 2022-04
- Subjects: Public housing South Africa Buffalo City , Squatters South Africa Buffalo City , Occupancy (Law) South Africa , Acquisition of property South Africa Buffalo City , Right of property South Africa Buffalo City , Sociology, Urban South Africa Buffalo City , Marginality, Social South Africa Buffalo City , Human rights South Africa , Acquisition of property Moral and ethical aspects South Africa Buffalo City , Urban poor South Africa Buffalo City Social conditions
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232790 , vital:50025 , DOI 10.21504/10962/232790
- Description: This thesis examines contestations around access to state-provided housing or simply state housing in South Africa, using a case study of two sites in Buffalo City Municipality, and with a particular focus on occupation without ownership through informal and illegal means. While the South African state, based on an official human rights discourse and regime, seeks to provide state housing to the urban poor, massive housing backlogs continue to exist within urban spaces. As a result, the urban poor turn to self-provisioning through the construction of informal settlements or backyard shacks, waiting at times indefinitely to be allocated a state house via the official housing waiting lists. To overcome this problem, some amongst the urban poor opt to circumvent the process by invading and illegally occupying state houses, leading to occupation without ownership. In doing so, they draw upon their own moral rights-claims to justify their actions. The thesis examines the multiple causes for occupation and ownership contestations in the two research sites as well as the different forms that these contestations take. The study is framed theoretically in terms of a sociology of human rights, identifying and analysing how moral claims to rights amongst ordinary people often come into conflict with a legal-institutional conception of rights adopted by the state. The study also draws on a diverse array of theorists whose work speaks to the manner in which ordinary citizens develop their own ways of acting contrary to state officialdom. Using interpretive sociology, the study considers the views and practices of those illegally occupying houses without ownership and those who feel victimised by these informal actions. It considers these intra-community dynamics in light of the machinations of local state powerholders at municipal level. As with interpretive sociology, then, the thesis privileges social realms of meanings, interpretations, experiences and practices of human agents. Informal state housing occupations in the Buffalo City Municipality are caused by a number of factors related to state incapacity, weak policies and poor planning, corruption, resource constraints and so on. The study vividly demonstrates the tensions arising and existing between the South African state’s legal human rights regime and locally-constructed moral-rights regimes amongst the urban poor. This tension is seen in the interrelated phenomena of ‘occupation without ownership’ and ‘ownership without occupation’, as the poor draw upon and use ordinary logics of rights for recourse. The thesis shows how diverse rights regimes lead to intra-community conflict, in particular along generational and racial lines. , Thesis (PhD) -- Humanities, Sociology, 2022
- Full Text:
- Date Issued: 2022-04
Rethinking our understanding of career decision making: the views of students at a selected South African TVET colleges on what influences their career decisions
- Authors: Maluleke, Lucky
- Date: 2022-04
- Subjects: Career -- Decision making , Postsecondary education -- South Africa , Career development
- Language: English
- Type: Doctoral thesis , Thesis
- Identifier: http://hdl.handle.net/10948/56044 , vital:54946
- Description: In South Africa, technical and vocational education and training (TVET) has been identified as a potential solution to the triple challenge of inequality, poverty and unemployment. The 2013 White Paper for Post-School Education and Training: Building on Expanded, Effective and Integrated Post-School Education (DHET, 2013) identifies TVET colleges as an area of great expansion. Although such an expansion is important and necessary, it is unfortunate that in South Africa, research has paid little to no attention to what influences TVET college students' career decision making. Concerning this, the study reported in this dissertation aimed to investigate what influences the career decision making of TVET college students in the Nelson Mandela Bay Metro, Eastern Cape, South Africa. This qualitative study, located within the subjectivist ontology and interpretivist epistemology, contributes to understanding what influences the career decision making of TVET college students in a developing context of South Africa. Drawing on qualitative (individual and group) interviews with students, it examined the career decisions of a small sample of students enrolled at one South African public TVET college in the Nelson Mandela Bay Metro. In so doing, the study brings four elements to the study of career decision making. Firstly, empirically, it brings a fresh and subjective perspective of what 'TVET' and 'career' means to TVET students. Secondly, it brings to the literature on TVET, an analysis of the Careership Theory that draws from the TVET college students' experiences. Thirdly, it brings to our understanding of career decision making, the role of structure and agency from a Bourdieusian2 perspective. Fourthly, it transcends the heavily critiqued Bourdieusian model to encompass the notion of capacity to aspire, borrowed from Arjun Appadurai, to better explain the role of culture in social action. Data were collected using individual and group interview methods, which were later transcribed and analysed thematically. The findings show that career decision making is dependent on the perceptions of the primary decision makers and other social agents that learners interacted with in the field. Career decision making is situated in the vast social inequalities and unequal power relations shaped by unequal access to cultural, economic and social capital. However, as much as social structures influence career decision making, the role of agency must not be underestimated. The findings further reveal that career decisions are located in the objective and social structures, and these are influenced by capital (cultural, economic and social). Furthermore, career decisions are influenced by the capacity of the individuals to choose, to know what to choose, as well as structural enablers like finance. In short, the findings reveal that inequalities matter, for example, socio-economic and gender disparities. , Thesis (DEd) -- Faculty of Education, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Maluleke, Lucky
- Date: 2022-04
- Subjects: Career -- Decision making , Postsecondary education -- South Africa , Career development
- Language: English
- Type: Doctoral thesis , Thesis
- Identifier: http://hdl.handle.net/10948/56044 , vital:54946
- Description: In South Africa, technical and vocational education and training (TVET) has been identified as a potential solution to the triple challenge of inequality, poverty and unemployment. The 2013 White Paper for Post-School Education and Training: Building on Expanded, Effective and Integrated Post-School Education (DHET, 2013) identifies TVET colleges as an area of great expansion. Although such an expansion is important and necessary, it is unfortunate that in South Africa, research has paid little to no attention to what influences TVET college students' career decision making. Concerning this, the study reported in this dissertation aimed to investigate what influences the career decision making of TVET college students in the Nelson Mandela Bay Metro, Eastern Cape, South Africa. This qualitative study, located within the subjectivist ontology and interpretivist epistemology, contributes to understanding what influences the career decision making of TVET college students in a developing context of South Africa. Drawing on qualitative (individual and group) interviews with students, it examined the career decisions of a small sample of students enrolled at one South African public TVET college in the Nelson Mandela Bay Metro. In so doing, the study brings four elements to the study of career decision making. Firstly, empirically, it brings a fresh and subjective perspective of what 'TVET' and 'career' means to TVET students. Secondly, it brings to the literature on TVET, an analysis of the Careership Theory that draws from the TVET college students' experiences. Thirdly, it brings to our understanding of career decision making, the role of structure and agency from a Bourdieusian2 perspective. Fourthly, it transcends the heavily critiqued Bourdieusian model to encompass the notion of capacity to aspire, borrowed from Arjun Appadurai, to better explain the role of culture in social action. Data were collected using individual and group interview methods, which were later transcribed and analysed thematically. The findings show that career decision making is dependent on the perceptions of the primary decision makers and other social agents that learners interacted with in the field. Career decision making is situated in the vast social inequalities and unequal power relations shaped by unequal access to cultural, economic and social capital. However, as much as social structures influence career decision making, the role of agency must not be underestimated. The findings further reveal that career decisions are located in the objective and social structures, and these are influenced by capital (cultural, economic and social). Furthermore, career decisions are influenced by the capacity of the individuals to choose, to know what to choose, as well as structural enablers like finance. In short, the findings reveal that inequalities matter, for example, socio-economic and gender disparities. , Thesis (DEd) -- Faculty of Education, 2022
- Full Text:
- Date Issued: 2022-04
The mechanisms conditioning doctoral supervision development in public universities across South Africa
- Authors: Motshoane, Puleng Lorraine
- Date: 2022-04
- Subjects: Doctoral students South Africa , Graduate students Supervision of South Africa , Agent (Philosophy) , Public universities and colleges South Africa , Supervisors Training of South Africa , Supervision South Africa , Mentoring in education South Africa
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232305 , vital:49980 , DOI 10.21504/10962/232305
- Description: This study offers a social realist account of how South African public institutions develop emerging supervisors. The study addresses the need for supervision development across South African public higher education universities. The purpose of the study was to answer the question “What mechanisms condition the development and support of emerging doctoral supervisors across South African public universities?” To examine this question, analytical dualism was used to separate the roles of the ‘people’ (agents) from the ‘parts’ (structure and culture) to examine their interplay. The study was qualitative, and the data was generated through documents, an online survey, and semi-structured interviews. One hundred and eighty-six participants responded to the survey and fifty-four people were interviewed. The participants came from twenty of the twenty-six public higher education universities and represent a large range of disciplines. The study findings revealed that emerging supervisors were often simply ‘thrown into the deep-end’ as they had to work out how to supervise by learning from their students and using the experience gained while they were being supervised. This was experienced as highly problematic by the participants who shared this understanding. Secondly, the findings suggest that where there were developmental events in place, some were not well received. For example where those providing the training were not regarded as credible because they lacked the supervision experience or because the interventions were seen to be too ad hoc and generic. There were calls for more discipline-specific interventions and collaborative spaces where emerging supervisors could engage with experienced supervisors rather than being instructed in a generic best-practice of ‘how to supervise’. The findings indicated that the lines between co-supervision and mentoring were often blurred, and both were used as another form of supervision development. Such relationships provided a useful means for emerging supervisors to come to understand the complex pedagogy of postgraduate supervision but were at times constrained by power imbalances. It was evident across the data that supervision is a special form of teaching and needs to be conceptualised at least in part as a pedagogy. Moreover, the issue of institutional differentiation needs to be considered for the sector to achieve its intended goals of increasing doctoral output and to be able to participate fully in the knowledge economy. , Phuputso ena e fana ka tlaleho ea 'nete ea kahisano ea kamoo litsi tsa Afrika Boroa li ntlafatsang batsamaisi ba ntseng ba hlaha. Phuputso ena e sebetsana le tlhokeho ya ntshetsopele ya bolebedi ho tswa ho diyunibesithing tsa thuto e phahameng tsa setjhaba tsa Aforika Borwa. Sepheo sa phuputso e ne e le ho araba potso e mabapi le "Ke mekhoa efe e behang nts'etsopele le tšehetso ea baokameli ba ntseng ba tsoela pele ho pholletsa le liunivesithi tsa sechaba tsa Afrika Boroa?" E le ho hlahloba potso ena, ho ile ha sebelisoa li-analytical dualism ho arola likarolo tsa "batho" (baemeli) ho "likarolo" (sebopeho le setso) ho hlahloba likamano tsa bona. Thuto e ne e le ea boleng, 'me lintlha li ile tsa hlahisoa ka litokomane, phuputso ea inthaneteng, le lipuisano tse hlophisitsoeng hantle. Barupeluoa ba lekholo le mashome a robeli a metso e tšeletseng ba ile ba arabela phuputsong eo, 'me batho ba 54 ba botsoa. Barupeluoa ba ne ba tsoa liunivesithing tse mashome a mabeli ho tse mashome a mabeli a metso e tšeletseng tsa thuto e phahameng ea sechaba 'me ba emetse mefuta e mengata ea lithuto. Liphuputso tsa phuputso li senotse hore baokameli ba ntseng ba hlaha hangata ba ne ba ‘lahleloa botebong ba pelo kaha ba ne ba lokela ho etsa qeto ea ho laola ka ho ithuta ho liithuti tsa bona le ho sebelisa phihlelo eo ba e fumaneng ha ba ntse ba behiloe leihlo. Phihlelo ena e bile bothata haholo ho barupeluoa ba arolelanang boiphihlelo bona. Taba ea bobeli, liphuputso li fana ka maikutlo a hore ha liketsahalo tsa nts'etsopele li ntse li le teng, tse ling ha lia ka tsa amoheloa hantle, mohlala, hobane ba fanang ka koetliso ba ne ba sa nkoe e le ba ka tšeptjoang hobane ba ne ba se na boiphihlelo ba bolebeli kapa hobane ho ne ho bonahala hore ho na le mehato ea nakoana. . Ho bile le meipiletso ea hore ho be le litšebetso tse khethehileng tsa khalemelo le libaka tse kopanetsoeng moo baokameli ba neng ba ka buisana le baokameli ba nang le phihlelo ho e-na le ho rutoa ka mokhoa o tloaelehileng oa 'ho laola'. Liphuputso li bonts'itse hore litsela tse pakeng tsa ts'ebelisano-'moho le boeletsi hangata li ne li sa hlaka. Ho feta moo, ka bobeli li ne li sebelisoa e le mofuta o mong oa ntlafatso ea tlhokomelo. Likamano tse joalo li ne li fana ka mokhoa oa bohlokoa bakeng sa baokameli ba ba qalang ho utloisisa thuto e rarahaneng ea bolebeli ba morao-rao empa ka linako tse ling ba ne ba sitisoa ke ho se leka-lekane ha matla. Ho ile ha totobala ho pholletsa le data hore tsamaiso ke mokhoa o ikhethileng oa ho ruta 'me o hloka ho nahanoa bonyane e le mokhoa oa ho ruta. Ho feta moo, taba ea karohano ea litsi e lokela ho shejoa hore lekala le fihlele lipheo tsa lona tse reriloeng tsa ho eketsa tlhahiso ea bongaka le ho kenya letsoho ka botlalo moruong oa tsebo. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Motshoane, Puleng Lorraine
- Date: 2022-04
- Subjects: Doctoral students South Africa , Graduate students Supervision of South Africa , Agent (Philosophy) , Public universities and colleges South Africa , Supervisors Training of South Africa , Supervision South Africa , Mentoring in education South Africa
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232305 , vital:49980 , DOI 10.21504/10962/232305
- Description: This study offers a social realist account of how South African public institutions develop emerging supervisors. The study addresses the need for supervision development across South African public higher education universities. The purpose of the study was to answer the question “What mechanisms condition the development and support of emerging doctoral supervisors across South African public universities?” To examine this question, analytical dualism was used to separate the roles of the ‘people’ (agents) from the ‘parts’ (structure and culture) to examine their interplay. The study was qualitative, and the data was generated through documents, an online survey, and semi-structured interviews. One hundred and eighty-six participants responded to the survey and fifty-four people were interviewed. The participants came from twenty of the twenty-six public higher education universities and represent a large range of disciplines. The study findings revealed that emerging supervisors were often simply ‘thrown into the deep-end’ as they had to work out how to supervise by learning from their students and using the experience gained while they were being supervised. This was experienced as highly problematic by the participants who shared this understanding. Secondly, the findings suggest that where there were developmental events in place, some were not well received. For example where those providing the training were not regarded as credible because they lacked the supervision experience or because the interventions were seen to be too ad hoc and generic. There were calls for more discipline-specific interventions and collaborative spaces where emerging supervisors could engage with experienced supervisors rather than being instructed in a generic best-practice of ‘how to supervise’. The findings indicated that the lines between co-supervision and mentoring were often blurred, and both were used as another form of supervision development. Such relationships provided a useful means for emerging supervisors to come to understand the complex pedagogy of postgraduate supervision but were at times constrained by power imbalances. It was evident across the data that supervision is a special form of teaching and needs to be conceptualised at least in part as a pedagogy. Moreover, the issue of institutional differentiation needs to be considered for the sector to achieve its intended goals of increasing doctoral output and to be able to participate fully in the knowledge economy. , Phuputso ena e fana ka tlaleho ea 'nete ea kahisano ea kamoo litsi tsa Afrika Boroa li ntlafatsang batsamaisi ba ntseng ba hlaha. Phuputso ena e sebetsana le tlhokeho ya ntshetsopele ya bolebedi ho tswa ho diyunibesithing tsa thuto e phahameng tsa setjhaba tsa Aforika Borwa. Sepheo sa phuputso e ne e le ho araba potso e mabapi le "Ke mekhoa efe e behang nts'etsopele le tšehetso ea baokameli ba ntseng ba tsoela pele ho pholletsa le liunivesithi tsa sechaba tsa Afrika Boroa?" E le ho hlahloba potso ena, ho ile ha sebelisoa li-analytical dualism ho arola likarolo tsa "batho" (baemeli) ho "likarolo" (sebopeho le setso) ho hlahloba likamano tsa bona. Thuto e ne e le ea boleng, 'me lintlha li ile tsa hlahisoa ka litokomane, phuputso ea inthaneteng, le lipuisano tse hlophisitsoeng hantle. Barupeluoa ba lekholo le mashome a robeli a metso e tšeletseng ba ile ba arabela phuputsong eo, 'me batho ba 54 ba botsoa. Barupeluoa ba ne ba tsoa liunivesithing tse mashome a mabeli ho tse mashome a mabeli a metso e tšeletseng tsa thuto e phahameng ea sechaba 'me ba emetse mefuta e mengata ea lithuto. Liphuputso tsa phuputso li senotse hore baokameli ba ntseng ba hlaha hangata ba ne ba ‘lahleloa botebong ba pelo kaha ba ne ba lokela ho etsa qeto ea ho laola ka ho ithuta ho liithuti tsa bona le ho sebelisa phihlelo eo ba e fumaneng ha ba ntse ba behiloe leihlo. Phihlelo ena e bile bothata haholo ho barupeluoa ba arolelanang boiphihlelo bona. Taba ea bobeli, liphuputso li fana ka maikutlo a hore ha liketsahalo tsa nts'etsopele li ntse li le teng, tse ling ha lia ka tsa amoheloa hantle, mohlala, hobane ba fanang ka koetliso ba ne ba sa nkoe e le ba ka tšeptjoang hobane ba ne ba se na boiphihlelo ba bolebeli kapa hobane ho ne ho bonahala hore ho na le mehato ea nakoana. . Ho bile le meipiletso ea hore ho be le litšebetso tse khethehileng tsa khalemelo le libaka tse kopanetsoeng moo baokameli ba neng ba ka buisana le baokameli ba nang le phihlelo ho e-na le ho rutoa ka mokhoa o tloaelehileng oa 'ho laola'. Liphuputso li bonts'itse hore litsela tse pakeng tsa ts'ebelisano-'moho le boeletsi hangata li ne li sa hlaka. Ho feta moo, ka bobeli li ne li sebelisoa e le mofuta o mong oa ntlafatso ea tlhokomelo. Likamano tse joalo li ne li fana ka mokhoa oa bohlokoa bakeng sa baokameli ba ba qalang ho utloisisa thuto e rarahaneng ea bolebeli ba morao-rao empa ka linako tse ling ba ne ba sitisoa ke ho se leka-lekane ha matla. Ho ile ha totobala ho pholletsa le data hore tsamaiso ke mokhoa o ikhethileng oa ho ruta 'me o hloka ho nahanoa bonyane e le mokhoa oa ho ruta. Ho feta moo, taba ea karohano ea litsi e lokela ho shejoa hore lekala le fihlele lipheo tsa lona tse reriloeng tsa ho eketsa tlhahiso ea bongaka le ho kenya letsoho ka botlalo moruong oa tsebo. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-04
A reflective multiple case study approach to understanding partner relationships within the context of community engagement at Rhodes University
- Authors: Bobo, Azola Benita Dorothea
- Date: 2021-05-06
- Subjects: Community development South Africa Makhanda , Community and college South Africa Makhanda , Community psychology South Africa Makhanda , Decolonization South Africa , Social action South Africa Makhanda , Transformative learning South Africa Makhanda , Rhodes University , Rhodes University Community Engagement (RUCE)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/253854 , vital:52406 , DOI 10.21504/10962/253854
- Description: Using a social constructivist approach, within the social action model of community psychology, this research interrogates the features of successful community engagement partnerships that exist within the context of higher education. It draws on the co-management model that the Rhodes University Community Engagement (RUCE) division proposes, where partnerships are seen to be mutually beneficial. This research further interrogates whether the principles of community engagement that RUCE propose play out in reality, and whether systems of power are deconstructed, in working towards more equitable engagements. Drawing on the Early Childhood Development (ECD) Residence Programme for case studies, this research used a reflective multiple case study design in attempting to answer the research question. Four partner groups (i.e., 4 community partners and 4 community engagement representatives) were selected for this research. Each participant was interviewed twice (with a 6-month time gap) and also participated in two focus group discussions. Thematic analysis was used to analyse the findings. In taking a social justice approach, it can be argued that RUCE has made strides towards forming collaborative partnerships based on the ethics of ubuntu and aspects of transformative learning, which may lead to the decolonisation of higher education. However, critical engagement with the research findings suggests that in many cases the principles that RUCE propose are aspirational. More work needs to be done with both students and community partners to develop the kinds of partnerships that RUCE aspires to. This research provides valuable insight into how carefully managed community engagement partnerships in higher education have the potential to contribute to the transformation agenda of higher education institutions, while promoting equitable societies. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
- Date Issued: 2021-05-06
- Authors: Bobo, Azola Benita Dorothea
- Date: 2021-05-06
- Subjects: Community development South Africa Makhanda , Community and college South Africa Makhanda , Community psychology South Africa Makhanda , Decolonization South Africa , Social action South Africa Makhanda , Transformative learning South Africa Makhanda , Rhodes University , Rhodes University Community Engagement (RUCE)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/253854 , vital:52406 , DOI 10.21504/10962/253854
- Description: Using a social constructivist approach, within the social action model of community psychology, this research interrogates the features of successful community engagement partnerships that exist within the context of higher education. It draws on the co-management model that the Rhodes University Community Engagement (RUCE) division proposes, where partnerships are seen to be mutually beneficial. This research further interrogates whether the principles of community engagement that RUCE propose play out in reality, and whether systems of power are deconstructed, in working towards more equitable engagements. Drawing on the Early Childhood Development (ECD) Residence Programme for case studies, this research used a reflective multiple case study design in attempting to answer the research question. Four partner groups (i.e., 4 community partners and 4 community engagement representatives) were selected for this research. Each participant was interviewed twice (with a 6-month time gap) and also participated in two focus group discussions. Thematic analysis was used to analyse the findings. In taking a social justice approach, it can be argued that RUCE has made strides towards forming collaborative partnerships based on the ethics of ubuntu and aspects of transformative learning, which may lead to the decolonisation of higher education. However, critical engagement with the research findings suggests that in many cases the principles that RUCE propose are aspirational. More work needs to be done with both students and community partners to develop the kinds of partnerships that RUCE aspires to. This research provides valuable insight into how carefully managed community engagement partnerships in higher education have the potential to contribute to the transformation agenda of higher education institutions, while promoting equitable societies. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
- Date Issued: 2021-05-06
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