Schema therapy for anorexia nervosa: an intensive systematic individual case study
- Authors: Alexander, Graham
- Date: 2021-10-29
- Subjects: Eating disorders , Anorexia nervosa , Anorexia nervosa Treatment , Anorexia nervosa Case studies , Schema-focused cognitive therapy , Anorexic overcontroller , Interpretative phenomenological analysis (IPA)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/196082 , vital:45724 , DOI https://doi.org/10.21504/10962/196082
- Description: Developed more than three decades ago, schema therapy (ST) was born out of a need for a more effective way of working with difficult and challenging cases where patients were clearly unresponsive to the existing short-term cognitive therapies. While anchored in the primary theoretical orientation of cognitive therapy, ST has carefully integrated techniques and principles from attachment and object-relations therapies, as well as humanistic, gestalt and experiential therapies. The mode model emphasises the concept of “multiplicity” in terms of which the self is functionally divided into parts or schema modes. For a little more than a decade there has been growing interest amongst researcher-clinicians in the application of ST for the treatment of eating disorders (EDs) (Waller, et al., 2007; Simpson, 2012; Edwards, 2015; Munro et al., 2016; Simpson, 2016; Munro et al., 2016). While multivariate studies can provide quantifiable evidence for the efficacy of ST for treating EDs, systematic case-based research offers a means of engaging in an intensive analysis and description of the complex and subtle processes that unfold over time in a real-life therapeutic environment (Edwards et al., 2004; Yin, 1994). This research method also provides an opportunity for the refining of the clinical treatment model as well as its testing. Ten participants were assessed and treated with schema therapy. However, because of the large amount of data gathered, a decision was made to write up only one as an intensive systematic individual case study. Alison, an elderly woman with a longstanding history of AN who had been largely unresponsive to considerable previous therapies, received 100 ST sessions over a two-year period and showed a very positive response. The many challenges that arose and the way these were addressed within the ST framework provide an in-depth account of the application of the ST mode model for the treatment of AN. This is presented in a detailed therapy narrative. After results of the quantitative measures are provided, the next three chapters address three interpretative questions pertaining to the Healthy Adult/Vulnerable Child dyadic relationship, the processes of working with the Angry Child mode, and the conceptualising of an AN-specific coping mode. Several conclusions are drawn about the strengths of the schema therapy model and its particular application to AN. Amongst these is the importance of having a comprehensive case conceptualisation that serves as a collaborative “road map” with which to negotiate the unfolding collaborative therapeutic process. Another is the identifying of the “Anorexic Overcontroller” as a stand-alone coping mode that clarifies the functions of AN to hinder schema-based emotional injury, but paradoxically, still denies the individual’s basic core needs being met. Such a conceptualisation significantly assisted in the suspension of anorexic behaviour. A further significant observation is how emotion-focused work (especially within the context of chair work and imagery) brought therapy to life and was particularly effective in mobilising the conflict between internal voices. Another outstanding feature is how the building of a strong Healthy Adult mode proved vital in the healing process and the development of patient autonomy. Finally, therapy revealed how central the establishment of a sturdy, warm and loving therapeutic relationship is, and how influential the resonance between the therapist and patient is in the outcome of treatment. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Alexander, Graham
- Date: 2021-10-29
- Subjects: Eating disorders , Anorexia nervosa , Anorexia nervosa Treatment , Anorexia nervosa Case studies , Schema-focused cognitive therapy , Anorexic overcontroller , Interpretative phenomenological analysis (IPA)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/196082 , vital:45724 , DOI https://doi.org/10.21504/10962/196082
- Description: Developed more than three decades ago, schema therapy (ST) was born out of a need for a more effective way of working with difficult and challenging cases where patients were clearly unresponsive to the existing short-term cognitive therapies. While anchored in the primary theoretical orientation of cognitive therapy, ST has carefully integrated techniques and principles from attachment and object-relations therapies, as well as humanistic, gestalt and experiential therapies. The mode model emphasises the concept of “multiplicity” in terms of which the self is functionally divided into parts or schema modes. For a little more than a decade there has been growing interest amongst researcher-clinicians in the application of ST for the treatment of eating disorders (EDs) (Waller, et al., 2007; Simpson, 2012; Edwards, 2015; Munro et al., 2016; Simpson, 2016; Munro et al., 2016). While multivariate studies can provide quantifiable evidence for the efficacy of ST for treating EDs, systematic case-based research offers a means of engaging in an intensive analysis and description of the complex and subtle processes that unfold over time in a real-life therapeutic environment (Edwards et al., 2004; Yin, 1994). This research method also provides an opportunity for the refining of the clinical treatment model as well as its testing. Ten participants were assessed and treated with schema therapy. However, because of the large amount of data gathered, a decision was made to write up only one as an intensive systematic individual case study. Alison, an elderly woman with a longstanding history of AN who had been largely unresponsive to considerable previous therapies, received 100 ST sessions over a two-year period and showed a very positive response. The many challenges that arose and the way these were addressed within the ST framework provide an in-depth account of the application of the ST mode model for the treatment of AN. This is presented in a detailed therapy narrative. After results of the quantitative measures are provided, the next three chapters address three interpretative questions pertaining to the Healthy Adult/Vulnerable Child dyadic relationship, the processes of working with the Angry Child mode, and the conceptualising of an AN-specific coping mode. Several conclusions are drawn about the strengths of the schema therapy model and its particular application to AN. Amongst these is the importance of having a comprehensive case conceptualisation that serves as a collaborative “road map” with which to negotiate the unfolding collaborative therapeutic process. Another is the identifying of the “Anorexic Overcontroller” as a stand-alone coping mode that clarifies the functions of AN to hinder schema-based emotional injury, but paradoxically, still denies the individual’s basic core needs being met. Such a conceptualisation significantly assisted in the suspension of anorexic behaviour. A further significant observation is how emotion-focused work (especially within the context of chair work and imagery) brought therapy to life and was particularly effective in mobilising the conflict between internal voices. Another outstanding feature is how the building of a strong Healthy Adult mode proved vital in the healing process and the development of patient autonomy. Finally, therapy revealed how central the establishment of a sturdy, warm and loving therapeutic relationship is, and how influential the resonance between the therapist and patient is in the outcome of treatment. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2021
- Full Text:
- Date Issued: 2021-10-29
Shifting Norms and Practices of International Criminal Justice: Exploring African State and Non-State Agency at the International Criminal Court
- Authors: Mtero, Shingirai
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192875 , vital:45273
- Description: Thesis (PhD) -- Faculty of Humanities, Political and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mtero, Shingirai
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192875 , vital:45273
- Description: Thesis (PhD) -- Faculty of Humanities, Political and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
Stable Covalent pH-Sensitive Metallophthalocyanines Thin Monolayer Films for Selective Detection of Neurotransmitters
- Idowu, Abosede Omowumi Atinuke
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Synthesis, characterization and antiparasitic evaluation of chalcone hybrids
- Authors: Zulu, Ayanda Ignatia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192853 , vital:45271
- Description: Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Zulu, Ayanda Ignatia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192853 , vital:45271
- Description: Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Systematics of the Afrotropical Chalcididae (Hymenoptera: Chalcidoidea)
- Authors: Faure, Sariana
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192808 , vital:45266
- Description: Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Faure, Sariana
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192808 , vital:45266
- Description: Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
Taxonomic, ecological and biogeographic re-evaluation of temperate stream fishes in Southern Africa: a case study of the enteromius anoplus complex
- Authors: Kambikambi, Manda Juliet
- Date: 2021-10-29
- Subjects: Stream ecology South Africa , Barbs (Fish) Ecology South Africa Cape Fold Belt , Barbs (Fish) Ecology South Africa Highveld (Region) , Barbs (Fish) Ecology South Africa Amathole District Municipality , Biotic communities South Africa , Fishes Classification , Cryptic species , Chubbyhead barb
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191023 , vital:45051 , 10.21504/10962/191023
- Description: Worldwide, cryptic species, which comprise two or more distinct species that are classified as one due to their morphological similarity, are more common than previously thought. In South Africa, the chubbyhead barb, Enteromius anoplus (Weber, 1897), is the most widespread freshwater fish species. The widespread occurrence of this species across different river basins raised questions on its taxonomic status due to the likely occurrence of hidden diversity. This further raised the need to evaluate the ecological patterns associated with likely occurrence of such hidden diversity. Phylogenetic analyses of the cytochrome b gene of E. anoplus populations across South Africa revealed the occurrence of four genetically distinct species. These findings supported the restoration Enteromius cernuus (Barnard 1943) stat. rev. from the Olifants River system; the restoration of Enteromius anoplus sensu stricto (Weber 1897) stat. rev. from the Gouritz River system; the redescription of Enteromius oraniensis (Barnard 1943) stat. rev. from the Orange River system; and the description of a new species, Enteromius mandelai sp. nov. from the Eastern Cape rivers. Analyses of morphometric and meristic data revealed that these species were differentiated based on barbel length and number of lateral line scales. Ecological studies on Enteromius mandelai were conducted within headwater streams of major river systems in the Eastern Cape region. These headwater streams had different catchment characteristics ranging from near-natural to anthropogenically-perturbed mainly due to agriculture-related disturbances and invasion of riparian zones by non-native plants. Stable isotope analysis provided evidence of trophic plasticity for E. mandelai across the different headwater streams. Specifically, E. mandelai exhibited large isotopic niches in agriculture-disturbed headwater streams, whereas small isotopic niches were observed in headwater streams invaded by non-native plants. Because of the evidence of trophic plasticity for E. mandelai, this study further hypothesized that this species would exhibit variable environmental niche patterns related to its distribution, abundance and the presence of contra-specifics due to different abiotic factors across its range. Enteromius mandelai was generally most abundant at sites with high total dissolved solids and sand substratum, which was characteristic of large pool habitats, and least abundant at sites with high turbidity. In the Great Fish River, E. mandelai occurred as the only species in most headwater sites, whereas in the Keiskamma and Buffalo River systems, it co-occurred with Amatolacypris trevelyani and Sandelia bainsii. Enteromius mandelai was, nevertheless, found to be ubiquitous together with having wide environmental niches, and exhibited no discernible patterns in its habitat associations. The taxonomic re-evaluation of the E. anoplus complex, which provided evidence of the existence of new species, has implications for the biogeographic zonation of the ichthyofauna of the Cape Fold Ecoregion (CFE), Amathole-Winterberg Highlands Ecoregion (AWHE) and the Southern Temperate Highveld Ecoregion (STHE). For example, the currently recognised southern limit of the STHE, which encompasses the AWHE, is based on the occurrence of E. anoplus, Enteromius pallidus and Labeo umbratus. However, evidence from this and other recent studies indicate the occurrence of either new species or distinct lineages in the southern-most section of the STHE, which is consistent with the patterns observed in the CFE. Comparison of taxonomic composition showed that species in the eastern part of the CFE were similar to species in the AWHE and the southern-most section of the STHE. Because of the close affinities among most of the new taxa in these regions, this study proposes that the current delimitation of the CFE should be reviewed by extending it to include the AWHE and sections of the STHE. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Kambikambi, Manda Juliet
- Date: 2021-10-29
- Subjects: Stream ecology South Africa , Barbs (Fish) Ecology South Africa Cape Fold Belt , Barbs (Fish) Ecology South Africa Highveld (Region) , Barbs (Fish) Ecology South Africa Amathole District Municipality , Biotic communities South Africa , Fishes Classification , Cryptic species , Chubbyhead barb
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191023 , vital:45051 , 10.21504/10962/191023
- Description: Worldwide, cryptic species, which comprise two or more distinct species that are classified as one due to their morphological similarity, are more common than previously thought. In South Africa, the chubbyhead barb, Enteromius anoplus (Weber, 1897), is the most widespread freshwater fish species. The widespread occurrence of this species across different river basins raised questions on its taxonomic status due to the likely occurrence of hidden diversity. This further raised the need to evaluate the ecological patterns associated with likely occurrence of such hidden diversity. Phylogenetic analyses of the cytochrome b gene of E. anoplus populations across South Africa revealed the occurrence of four genetically distinct species. These findings supported the restoration Enteromius cernuus (Barnard 1943) stat. rev. from the Olifants River system; the restoration of Enteromius anoplus sensu stricto (Weber 1897) stat. rev. from the Gouritz River system; the redescription of Enteromius oraniensis (Barnard 1943) stat. rev. from the Orange River system; and the description of a new species, Enteromius mandelai sp. nov. from the Eastern Cape rivers. Analyses of morphometric and meristic data revealed that these species were differentiated based on barbel length and number of lateral line scales. Ecological studies on Enteromius mandelai were conducted within headwater streams of major river systems in the Eastern Cape region. These headwater streams had different catchment characteristics ranging from near-natural to anthropogenically-perturbed mainly due to agriculture-related disturbances and invasion of riparian zones by non-native plants. Stable isotope analysis provided evidence of trophic plasticity for E. mandelai across the different headwater streams. Specifically, E. mandelai exhibited large isotopic niches in agriculture-disturbed headwater streams, whereas small isotopic niches were observed in headwater streams invaded by non-native plants. Because of the evidence of trophic plasticity for E. mandelai, this study further hypothesized that this species would exhibit variable environmental niche patterns related to its distribution, abundance and the presence of contra-specifics due to different abiotic factors across its range. Enteromius mandelai was generally most abundant at sites with high total dissolved solids and sand substratum, which was characteristic of large pool habitats, and least abundant at sites with high turbidity. In the Great Fish River, E. mandelai occurred as the only species in most headwater sites, whereas in the Keiskamma and Buffalo River systems, it co-occurred with Amatolacypris trevelyani and Sandelia bainsii. Enteromius mandelai was, nevertheless, found to be ubiquitous together with having wide environmental niches, and exhibited no discernible patterns in its habitat associations. The taxonomic re-evaluation of the E. anoplus complex, which provided evidence of the existence of new species, has implications for the biogeographic zonation of the ichthyofauna of the Cape Fold Ecoregion (CFE), Amathole-Winterberg Highlands Ecoregion (AWHE) and the Southern Temperate Highveld Ecoregion (STHE). For example, the currently recognised southern limit of the STHE, which encompasses the AWHE, is based on the occurrence of E. anoplus, Enteromius pallidus and Labeo umbratus. However, evidence from this and other recent studies indicate the occurrence of either new species or distinct lineages in the southern-most section of the STHE, which is consistent with the patterns observed in the CFE. Comparison of taxonomic composition showed that species in the eastern part of the CFE were similar to species in the AWHE and the southern-most section of the STHE. Because of the close affinities among most of the new taxa in these regions, this study proposes that the current delimitation of the CFE should be reviewed by extending it to include the AWHE and sections of the STHE. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
Tense and aspect in Xhosa
- Authors: Savić, Stefan
- Date: 2021-10-29
- Subjects: Xhosa language , Xhosa language Grammar , Xhosa language Semantics , Xhosa language Tense , Xhosa language Aspect , Xhosa language Syntax , Xhosa language Morphology , Xhosa language Grammar, Comparative , Information structure
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192897 , vital:45277 , 10.21504/10962/192897
- Description: This dissertation investigates the semantics of each tense and aspect in Xhosa. Since tense and aspect perform important pragmatic functions, the analysis takes into account the correlation between the verb and the wider discourse in which it is embedded. Tense reflects the temporal relation between the time of the utterance (speech time) and an interval the speaker makes the assertion about (reference time). The Remote Past and the Remote Future tenses differ from their Recent/Immediate counterparts in that they denote events which occurred in a significantly different situation than the speech time and/or events in the surrounding discourse. Aspect does not only indicate the relation between the time occupied by the real world event and the reference time chosen by the speaker. The Perfective aspect represents an event as a unique change-of-state that pertains to a single point on the timeline which at the same time functions as the reference time. By contrast, for the Imperfective aspect temporally links the event to a contextually provided reference time, e.g. the utterance time, a time adverbial, a period of time previously introduced in the preceding discourse, or the interlocutors’ shared experience. At the pragmatic level, the Perfective aspect tends to introduce an event’s resulting state into the discourse, whereas the Imperfective aspect tends to rule it out. Like the Imperfective aspect, the Anterior and the Prospective aspects assert an event’s occurrence from a contextually defined reference time. They refer to the consequent and the preparatory states of an event, respectively. On the pragmatic level, the Anterior aspect may also indicate that the truth-conditionality of the event’s resulting state is contradicted in the immediate discourse. This study shows that tense and aspect temporally represent different means of temporally assigning an event to a particular portion of the timeline. I further argue that aspect indicates whether the reference time is provided in the context (Imperfective, Anterior, Prospective) or whether it is introduced by the verb itself (Perfective). Furthermore, this study shows that aspect exhibits a pragmatic function by laying focus on different parts of the event that are relevant in the upcoming discourse. , Thesis (PhD) -- Faculty of Humanities, Linguistics and Applied Languages Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Savić, Stefan
- Date: 2021-10-29
- Subjects: Xhosa language , Xhosa language Grammar , Xhosa language Semantics , Xhosa language Tense , Xhosa language Aspect , Xhosa language Syntax , Xhosa language Morphology , Xhosa language Grammar, Comparative , Information structure
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192897 , vital:45277 , 10.21504/10962/192897
- Description: This dissertation investigates the semantics of each tense and aspect in Xhosa. Since tense and aspect perform important pragmatic functions, the analysis takes into account the correlation between the verb and the wider discourse in which it is embedded. Tense reflects the temporal relation between the time of the utterance (speech time) and an interval the speaker makes the assertion about (reference time). The Remote Past and the Remote Future tenses differ from their Recent/Immediate counterparts in that they denote events which occurred in a significantly different situation than the speech time and/or events in the surrounding discourse. Aspect does not only indicate the relation between the time occupied by the real world event and the reference time chosen by the speaker. The Perfective aspect represents an event as a unique change-of-state that pertains to a single point on the timeline which at the same time functions as the reference time. By contrast, for the Imperfective aspect temporally links the event to a contextually provided reference time, e.g. the utterance time, a time adverbial, a period of time previously introduced in the preceding discourse, or the interlocutors’ shared experience. At the pragmatic level, the Perfective aspect tends to introduce an event’s resulting state into the discourse, whereas the Imperfective aspect tends to rule it out. Like the Imperfective aspect, the Anterior and the Prospective aspects assert an event’s occurrence from a contextually defined reference time. They refer to the consequent and the preparatory states of an event, respectively. On the pragmatic level, the Anterior aspect may also indicate that the truth-conditionality of the event’s resulting state is contradicted in the immediate discourse. This study shows that tense and aspect temporally represent different means of temporally assigning an event to a particular portion of the timeline. I further argue that aspect indicates whether the reference time is provided in the context (Imperfective, Anterior, Prospective) or whether it is introduced by the verb itself (Perfective). Furthermore, this study shows that aspect exhibits a pragmatic function by laying focus on different parts of the event that are relevant in the upcoming discourse. , Thesis (PhD) -- Faculty of Humanities, Linguistics and Applied Languages Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
The biological control of Egeria densa Planch. (Hydrocharitaceae) in South Africa
- Authors: Smith, Rosali
- Date: 2021-10-29
- Subjects: Egeria (Plant genus) Biological control South Africa , Hydrocharitaceae Biological control South Africa , Aquatic weeds Biological control South Africa , Leafminers South Africa , Plant invasions South Africa , Resilience (Ecology) South Africa , Freshwater ecology South Africa , Hydrellia South Africa , Submerged macrophyte
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191102 , vital:45060 , 10.21504/10962/191102
- Description: Over the last thirty years, biological control, the use of host-specific natural enemies, has been a huge asset in the management exotic aquatic macrophytes such as Pistia stratiotes L. (Araceae), Pontederia crassipes Mart. (Solms) (Pontederiaceae), Azolla filiculoides Lam. (Azollaceae), Salvinia molesta D.S. Mitch (Salviniaceae) and Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae), also known as the “Big Bad Five” in South Africa. Despite these successes, freshwater ecosystems in South Africa have been harder to restore to an invasive macrophyte-free space, due to chronic disturbances such eutrophication, propagule dispersal and hydrological alterations. In the Anthropocene, where human activities have profound effects on their environment, these disturbances weakens ecological resilience and drive aquatic plant invasions. Due to long periods of invasions and the presence of a new suite of exotic aquatic plant propagules, native vegetation recolonization has been slow or even absent. Instead, the release of resources, such as sunlight, nutrient and space through aquatic weed management acts as a catalyst for secondary biological invasion. New invasive aquatic weeds include submerged and rooted emergent growth types, with Egeria densa Planch. (Hydrocharitaceae) the most widely distributed submerged aquatic weed in South Africa. It can quickly form dense monoculture stands that have ecological, economic and social impacts. Because of its ability to regenerate from plant fragments with double nodes, mechanical control is inappropriate. Additionally, mechanical and chemical control not only affects E. densa but have significant non-target effects. In response to its rapid spread over the last 20 years, especially following floating invasive aquatic management, a biological control programme was initiated, and in 2018, the leaf-mining fly, Hydrellia egeriae Rodrigues (Diptera: Ephydridae) was released. This was the first release of a biological control agent against E. densa in the world, and the first agent released against a submerged aquatic weed in South Africa. This thesis comprises the subsequent step of a biological control program when permission for the release of an agent have been obtained. A brief history of macrophyte invasions in South Africa’s unique freshwater systems are given in the literature review. Contributing factors to secondary invasions within the context of ecological resilience are introduced. An argument for the benefit of biological control as nuisance control is given, especially because E. densa and its natural enemy, H. egeriae is the focus species of this thesis. The main goal after permission for the release of an agent have been obtained, is to establish and build-up field populations. Research questions in this thesis aimed to investigate factors that contribute to or negate this goal. Through laboratory and field experiments we investigated the thermal physiology of the agent, and its climatic suitability to its novel range; different release strategies on field establishment and biotic resistance through the acquisition of novel parasitoids. Considering the longevity of this biological control program, we investigated the effects of elevated CO2 on the interaction between E. densa and H. egeriae through open top chamber experiments. Laboratory thermal physiology results showed that the agent is able to survive, develop and proliferate at all E. densa sites throughout the year. This is confirmed with the establishment of the agent at two release sites, the Nahoon River in the Eastern Cape Province and the Midmar Dam in KwaZulu-Natal. Post-release surveys showed that H. egeriae requires augmentative releases to sustain field populations. Without augmentative releases, H. egeriae herbivory levels were almost negligent. However, a contributing factor to low field-populations was parasitism. The biological control agent acquired three parasitoids, which have previously been described from Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a specific herbivore to Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). These results provide information on the immediate establishment and effectiveness of the H. egeriae. Results from the elevated CO2 study suggest that E. densa will become less nutritious through a shift in leaf C/N ratio, when ambient 800ppm is bubbled into experimental growth chambers. Hydrellia egeriae feeding was affected by ambient CO2 levels and plant nutrient availability. The set levels of ambient CO2 levels used in this experiment produced dissolved inorganic carbon levels that were lower than dissolved inorganic carbon levels in E. densa invaded sites. This suggests that, submerged aquatic plant-insect interactions may be harder to predict from only laboratory experiments. Further investigations are necessary to establish system-specific characteristics i.e. dissolved inorganic carbon and target plant nutritional quality. The biological control of E. densa in South Africa is still in its infancy. This study presents results from post-release surveys up until two years after the agent was released. From this study, Hydrellia egeriae exhibits the potential to be an effective biological control agent, but release strategies should be adapted to sustain field populations and to limit field parasitism effects. Continued post-release surveys will provide a more comprehensive idea of the seasonal fluctuations of field-populations and parasitism. Surveys at multiple sites will provide information on potential site specific characteristics that contribute to or negate biological effort. Considering the high nutrient status of South African freshwater systems, a more holistic approach to E. densa management is necessary. This will require the strengthening of ecological resilience to prevent systems from shifting into an alternate invasive stable state. In addition, aquatic weed management needs to be addressed by a resilient social network, which ultimately calls for the strengthening of socio-ecological resilience. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Smith, Rosali
- Date: 2021-10-29
- Subjects: Egeria (Plant genus) Biological control South Africa , Hydrocharitaceae Biological control South Africa , Aquatic weeds Biological control South Africa , Leafminers South Africa , Plant invasions South Africa , Resilience (Ecology) South Africa , Freshwater ecology South Africa , Hydrellia South Africa , Submerged macrophyte
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191102 , vital:45060 , 10.21504/10962/191102
- Description: Over the last thirty years, biological control, the use of host-specific natural enemies, has been a huge asset in the management exotic aquatic macrophytes such as Pistia stratiotes L. (Araceae), Pontederia crassipes Mart. (Solms) (Pontederiaceae), Azolla filiculoides Lam. (Azollaceae), Salvinia molesta D.S. Mitch (Salviniaceae) and Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae), also known as the “Big Bad Five” in South Africa. Despite these successes, freshwater ecosystems in South Africa have been harder to restore to an invasive macrophyte-free space, due to chronic disturbances such eutrophication, propagule dispersal and hydrological alterations. In the Anthropocene, where human activities have profound effects on their environment, these disturbances weakens ecological resilience and drive aquatic plant invasions. Due to long periods of invasions and the presence of a new suite of exotic aquatic plant propagules, native vegetation recolonization has been slow or even absent. Instead, the release of resources, such as sunlight, nutrient and space through aquatic weed management acts as a catalyst for secondary biological invasion. New invasive aquatic weeds include submerged and rooted emergent growth types, with Egeria densa Planch. (Hydrocharitaceae) the most widely distributed submerged aquatic weed in South Africa. It can quickly form dense monoculture stands that have ecological, economic and social impacts. Because of its ability to regenerate from plant fragments with double nodes, mechanical control is inappropriate. Additionally, mechanical and chemical control not only affects E. densa but have significant non-target effects. In response to its rapid spread over the last 20 years, especially following floating invasive aquatic management, a biological control programme was initiated, and in 2018, the leaf-mining fly, Hydrellia egeriae Rodrigues (Diptera: Ephydridae) was released. This was the first release of a biological control agent against E. densa in the world, and the first agent released against a submerged aquatic weed in South Africa. This thesis comprises the subsequent step of a biological control program when permission for the release of an agent have been obtained. A brief history of macrophyte invasions in South Africa’s unique freshwater systems are given in the literature review. Contributing factors to secondary invasions within the context of ecological resilience are introduced. An argument for the benefit of biological control as nuisance control is given, especially because E. densa and its natural enemy, H. egeriae is the focus species of this thesis. The main goal after permission for the release of an agent have been obtained, is to establish and build-up field populations. Research questions in this thesis aimed to investigate factors that contribute to or negate this goal. Through laboratory and field experiments we investigated the thermal physiology of the agent, and its climatic suitability to its novel range; different release strategies on field establishment and biotic resistance through the acquisition of novel parasitoids. Considering the longevity of this biological control program, we investigated the effects of elevated CO2 on the interaction between E. densa and H. egeriae through open top chamber experiments. Laboratory thermal physiology results showed that the agent is able to survive, develop and proliferate at all E. densa sites throughout the year. This is confirmed with the establishment of the agent at two release sites, the Nahoon River in the Eastern Cape Province and the Midmar Dam in KwaZulu-Natal. Post-release surveys showed that H. egeriae requires augmentative releases to sustain field populations. Without augmentative releases, H. egeriae herbivory levels were almost negligent. However, a contributing factor to low field-populations was parasitism. The biological control agent acquired three parasitoids, which have previously been described from Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a specific herbivore to Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). These results provide information on the immediate establishment and effectiveness of the H. egeriae. Results from the elevated CO2 study suggest that E. densa will become less nutritious through a shift in leaf C/N ratio, when ambient 800ppm is bubbled into experimental growth chambers. Hydrellia egeriae feeding was affected by ambient CO2 levels and plant nutrient availability. The set levels of ambient CO2 levels used in this experiment produced dissolved inorganic carbon levels that were lower than dissolved inorganic carbon levels in E. densa invaded sites. This suggests that, submerged aquatic plant-insect interactions may be harder to predict from only laboratory experiments. Further investigations are necessary to establish system-specific characteristics i.e. dissolved inorganic carbon and target plant nutritional quality. The biological control of E. densa in South Africa is still in its infancy. This study presents results from post-release surveys up until two years after the agent was released. From this study, Hydrellia egeriae exhibits the potential to be an effective biological control agent, but release strategies should be adapted to sustain field populations and to limit field parasitism effects. Continued post-release surveys will provide a more comprehensive idea of the seasonal fluctuations of field-populations and parasitism. Surveys at multiple sites will provide information on potential site specific characteristics that contribute to or negate biological effort. Considering the high nutrient status of South African freshwater systems, a more holistic approach to E. densa management is necessary. This will require the strengthening of ecological resilience to prevent systems from shifting into an alternate invasive stable state. In addition, aquatic weed management needs to be addressed by a resilient social network, which ultimately calls for the strengthening of socio-ecological resilience. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
The construction of phthalocyanine- carbon nanoparticle conjugates for applications in photodynamic therapy and non-linear optics
- Matshitse, Refilwe Manyama Stephina
- Authors: Matshitse, Refilwe Manyama Stephina
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanodiamonds , Photochemotherapy , Nonlinear optics , Quantum dots
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188397 , vital:44750 , 10.21504/10962/188397
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position and sometimes positively charged are reported. The Pcs had either H2, zinc or silicon as central metals and have pyridyloxy, benzothiozole phenoxy, and respective cationic analogues as ring substituents. The Pcs were linked to carbon based nanoparticles such as graphene quantum dots, carbon dots, and detonation nanodiamonds (DNDs) via an ester, amide bond and/or π - π stacking. The physicochemical characteristics of the Pcs were assessed when alone and when in a conjugated system. Both symmetrically and asymmetrically substituted benzothiozole Pcs when quaternised displayed higher triplet and singlet oxygen quantum yields than their unquaternised counterparts. Linkage to carbon nanoparticles (especially to detonation nanodiamonds) had an increasing effect on triplet and singlet oxygen quantum yield. However, a general decrease in singlet oxygen quantum yield on linkage to doped detonation nanodiamonds was associated with the screening effect of DNDs. Heteroatom doped DNDs-Pc nanohybrids have less singlet oxygen than Pcs alone due to molecular structural stability associated with strain that is relatively reduced upon linking Pcs. The In vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. When Pc complexes are alone, there is less phototoxicity with >22% cell viability at concentrations ≤ 50 μg/mL relative to conjugates with <22% cell viability at concentrations ≤ 50 μg/mL. There was no direct relationship between PDT and singlet oxygen quantum yields. Nonlinear optical characteristics of complexes was improved upon conjugation of DNDs. Absorbance, input energy, percentage loading, central metal, substituent of Pc and nature of interaction (covalent, noncovalent) are amongst some of the factors that influence nonlinear absorption properties of materials used in this study. All materials followed reverse saturable absorption through two photon absorption mechanism at the excitation wavelength of 532 nm. Aggregates reduce excited state lifetime and Beff under high concentrations/absorbance. A direct relationship between absorbance and Beff of DNDs nanoconjugated systems at low concentrations result in increased optical limiting characteristics of materials. The findings from this work show the importance of linking (nonlinear optics and photodynamic therapy) and doping (photodynamic therapy) photosensitisers such as phthalocyanines and sometimes boron dipyrromethenes onto carbon based nanoparticles for the enhanced characteristics in variable applications. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Matshitse, Refilwe Manyama Stephina
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanodiamonds , Photochemotherapy , Nonlinear optics , Quantum dots
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188397 , vital:44750 , 10.21504/10962/188397
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position and sometimes positively charged are reported. The Pcs had either H2, zinc or silicon as central metals and have pyridyloxy, benzothiozole phenoxy, and respective cationic analogues as ring substituents. The Pcs were linked to carbon based nanoparticles such as graphene quantum dots, carbon dots, and detonation nanodiamonds (DNDs) via an ester, amide bond and/or π - π stacking. The physicochemical characteristics of the Pcs were assessed when alone and when in a conjugated system. Both symmetrically and asymmetrically substituted benzothiozole Pcs when quaternised displayed higher triplet and singlet oxygen quantum yields than their unquaternised counterparts. Linkage to carbon nanoparticles (especially to detonation nanodiamonds) had an increasing effect on triplet and singlet oxygen quantum yield. However, a general decrease in singlet oxygen quantum yield on linkage to doped detonation nanodiamonds was associated with the screening effect of DNDs. Heteroatom doped DNDs-Pc nanohybrids have less singlet oxygen than Pcs alone due to molecular structural stability associated with strain that is relatively reduced upon linking Pcs. The In vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. When Pc complexes are alone, there is less phototoxicity with >22% cell viability at concentrations ≤ 50 μg/mL relative to conjugates with <22% cell viability at concentrations ≤ 50 μg/mL. There was no direct relationship between PDT and singlet oxygen quantum yields. Nonlinear optical characteristics of complexes was improved upon conjugation of DNDs. Absorbance, input energy, percentage loading, central metal, substituent of Pc and nature of interaction (covalent, noncovalent) are amongst some of the factors that influence nonlinear absorption properties of materials used in this study. All materials followed reverse saturable absorption through two photon absorption mechanism at the excitation wavelength of 532 nm. Aggregates reduce excited state lifetime and Beff under high concentrations/absorbance. A direct relationship between absorbance and Beff of DNDs nanoconjugated systems at low concentrations result in increased optical limiting characteristics of materials. The findings from this work show the importance of linking (nonlinear optics and photodynamic therapy) and doping (photodynamic therapy) photosensitisers such as phthalocyanines and sometimes boron dipyrromethenes onto carbon based nanoparticles for the enhanced characteristics in variable applications. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Towards effective monitoring, control and surveillance policy and implementation in South Africa and its relevance to other Southern African States
- Authors: Fikizolo, Lisolomzi Assaph
- Date: 2021-10-29
- Subjects: Fishery management Africa, Southern , Fisheries Monitoring Africa, Southern , Fishery policy Africa, Southern , Fishery law and legislation Africa, Southern , South Africa. Fisheries Management Branch
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190886 , vital:45038 , 10.21504/10962/190886
- Description: The responsibility of Fisheries Governance Authorities (FGAs) is to ensure that there is sustainable utilisation and exploitation of marine living resources through effective Monitoring, Control and Surveillance (MCS). MCS is a mechanism used to implement agreed policies, plans and strategies for oceans and fisheries governance, and it is key to their successful implementation. In the continent, the African Union (AU), through its agencies, economic and regional structures encourage and supports national and regional MCS programs. South Africa is a SADC coastal State with a fisheries governance branch mandated to ensure sustainable marine living resources’ utilisation with support from a national MCS program. This support depends on the effectiveness of the current national MCS organisational structure, capacity, legislative and policy framework, as well as regional cooperation. In addition to an extensive literature review, this study developed a MCS framework, following international fisheries legislation and guidelines, for testing the South African MCS’ conformity to such a model. Furthermore, Namibia and Mozambique were included as examples of SADC coastal States to determine their responsiveness to regional cooperation and coordination. Based on the framework, a questionnaire with four parts, Part A: Background Information; Part B: Evaluation of MCS Enablers; Part C: Evaluation of an MCS system process and its effectiveness – reactive approach; and Part D: - proactive approach was developed to collect information. The data was analysed, using appropriate statistical methods to determine, against set characteristics, the level of information that the government respondents could provide to the research topic, and to determine the effectiveness of the South African MCS program. Limited information from Namibia and Mozambique showed readiness in their respective MCS programs for a regional MCS integrated approach, as is the case with South Africa, but there is no serious engagement to implement any regional MCS program. Results showed that the South African MCS program's effectiveness is generally adequate, but there are challenges with planning; financial resources; MCS equipment; stakeholder engagement processes, and governance. A primary recommendation from this study was that business plans, as utilised in the private sector, should be developed by South African Fisheries Governance Authority (FGA) to address MCS governance shortcomings as revealed by this study. A reconfiguration of the MCS organisational structure to include a resource mobilisation unit is considered necessary to effect the much needed improvements. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Fikizolo, Lisolomzi Assaph
- Date: 2021-10-29
- Subjects: Fishery management Africa, Southern , Fisheries Monitoring Africa, Southern , Fishery policy Africa, Southern , Fishery law and legislation Africa, Southern , South Africa. Fisheries Management Branch
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190886 , vital:45038 , 10.21504/10962/190886
- Description: The responsibility of Fisheries Governance Authorities (FGAs) is to ensure that there is sustainable utilisation and exploitation of marine living resources through effective Monitoring, Control and Surveillance (MCS). MCS is a mechanism used to implement agreed policies, plans and strategies for oceans and fisheries governance, and it is key to their successful implementation. In the continent, the African Union (AU), through its agencies, economic and regional structures encourage and supports national and regional MCS programs. South Africa is a SADC coastal State with a fisheries governance branch mandated to ensure sustainable marine living resources’ utilisation with support from a national MCS program. This support depends on the effectiveness of the current national MCS organisational structure, capacity, legislative and policy framework, as well as regional cooperation. In addition to an extensive literature review, this study developed a MCS framework, following international fisheries legislation and guidelines, for testing the South African MCS’ conformity to such a model. Furthermore, Namibia and Mozambique were included as examples of SADC coastal States to determine their responsiveness to regional cooperation and coordination. Based on the framework, a questionnaire with four parts, Part A: Background Information; Part B: Evaluation of MCS Enablers; Part C: Evaluation of an MCS system process and its effectiveness – reactive approach; and Part D: - proactive approach was developed to collect information. The data was analysed, using appropriate statistical methods to determine, against set characteristics, the level of information that the government respondents could provide to the research topic, and to determine the effectiveness of the South African MCS program. Limited information from Namibia and Mozambique showed readiness in their respective MCS programs for a regional MCS integrated approach, as is the case with South Africa, but there is no serious engagement to implement any regional MCS program. Results showed that the South African MCS program's effectiveness is generally adequate, but there are challenges with planning; financial resources; MCS equipment; stakeholder engagement processes, and governance. A primary recommendation from this study was that business plans, as utilised in the private sector, should be developed by South African Fisheries Governance Authority (FGA) to address MCS governance shortcomings as revealed by this study. A reconfiguration of the MCS organisational structure to include a resource mobilisation unit is considered necessary to effect the much needed improvements. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10-29
Traversing Doctoral Borderlands: Black doctoral students’ experiences of identity construction in South Africa
- Authors: Hwami, Rudo Fortunate
- Date: 2021-10-29
- Subjects: Doctoral students South Africa , College students, Black South Africa , Marginality, Social South Africa , Public spaces Social aspects , Culture Social aspects , Rhythm , Identity (Psychology) , Borderlands Theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191062 , vital:45055 , 10.21504/10962/191062
- Description: Doctoral studies are described as a process of formation and becoming. This is an in-between space between unknowing and knowing, within and without the ivory tower of academia. In this in-between space the doctoral candidate takes the role of a novice and apprentice unlearning the student/unknowing past and learning to become a professional in academia. This project utilises the borderlands theory to understand the experiences of doctoral students as they undergo the process of becoming and intellectual identity formation. Whilst ‘journey’ and other metaphors that have been used to understand doctoral student experiences capture the process of becoming as a progression through the liminal stages – proposal, literature review, context, writing, reading etc. These stages presuppose temporality of being leading to stasis/completion. I argue that such conceptualisation of doctoral studies, although useful, depict one side of the story and provide a limited, monolithic, and homogenising understanding of the spatial configurations of doctoral space and intellectual identity formation. The dominant discourses of doctoral conceived and perceived space, liminal stages and understanding of doctoral student experiences, mask the more latent and intimate liminal stages of intellectual identity formation. Drawing from borderlands theory, I firstly argue for a holistic approach to understanding the spatiality of doctorate studies. Secondly, I argue that liminality is an everyday process integral to human existence where one is always in a state of ideological transition. An important state of liminality is the awareness of ‘Self’ in perpetual motion, caught between two worlds dominated/dominator and two ideologies of oppression/resistance. If this side of liminality is not made visible, institutional spaces, such as the doctorate, privileged with the power to disseminate and position onto-epistemologies as universal can be used to reproduce and reinforce exclusionary onto-epistemologies that subsequently impact intellectual identity formation. Using Lefebvre’s (1991) rhythmanalysis method, I use student experiences not as mere data for analysis, but as an act of envisioning, reinventing and coknowledge production to propose borderlands as a new metaphor to study doctoral spatial realities and the experiences of the students that traverse through it. , Thesis (PhD) -- Faculty of Humanities, Politics and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Hwami, Rudo Fortunate
- Date: 2021-10-29
- Subjects: Doctoral students South Africa , College students, Black South Africa , Marginality, Social South Africa , Public spaces Social aspects , Culture Social aspects , Rhythm , Identity (Psychology) , Borderlands Theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191062 , vital:45055 , 10.21504/10962/191062
- Description: Doctoral studies are described as a process of formation and becoming. This is an in-between space between unknowing and knowing, within and without the ivory tower of academia. In this in-between space the doctoral candidate takes the role of a novice and apprentice unlearning the student/unknowing past and learning to become a professional in academia. This project utilises the borderlands theory to understand the experiences of doctoral students as they undergo the process of becoming and intellectual identity formation. Whilst ‘journey’ and other metaphors that have been used to understand doctoral student experiences capture the process of becoming as a progression through the liminal stages – proposal, literature review, context, writing, reading etc. These stages presuppose temporality of being leading to stasis/completion. I argue that such conceptualisation of doctoral studies, although useful, depict one side of the story and provide a limited, monolithic, and homogenising understanding of the spatial configurations of doctoral space and intellectual identity formation. The dominant discourses of doctoral conceived and perceived space, liminal stages and understanding of doctoral student experiences, mask the more latent and intimate liminal stages of intellectual identity formation. Drawing from borderlands theory, I firstly argue for a holistic approach to understanding the spatiality of doctorate studies. Secondly, I argue that liminality is an everyday process integral to human existence where one is always in a state of ideological transition. An important state of liminality is the awareness of ‘Self’ in perpetual motion, caught between two worlds dominated/dominator and two ideologies of oppression/resistance. If this side of liminality is not made visible, institutional spaces, such as the doctorate, privileged with the power to disseminate and position onto-epistemologies as universal can be used to reproduce and reinforce exclusionary onto-epistemologies that subsequently impact intellectual identity formation. Using Lefebvre’s (1991) rhythmanalysis method, I use student experiences not as mere data for analysis, but as an act of envisioning, reinventing and coknowledge production to propose borderlands as a new metaphor to study doctoral spatial realities and the experiences of the students that traverse through it. , Thesis (PhD) -- Faculty of Humanities, Politics and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
Traversing Sonic Spaces: Expressions of Identity, Gender, and Power in the Musical Traditions of the Nupe in Northern Nigeria
- Authors: Njoku, Obianuju Akunna
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192886 , vital:45276
- Description: Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Njoku, Obianuju Akunna
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192886 , vital:45276
- Description: Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2021
- Full Text:
- Date Issued: 2021-10-29
Uncoupling the exploitation and climate change effects on the biology of Cape monkfish, Lophius vomerinus Valenciennes 1837 in Namibia
- Authors: Erasmus, Victoria Ndinelago
- Date: 2021-10-29
- Subjects: Lophius Namibia , Lophius Climatic factors Namibia , Lophius Effect of human beings on Namibia , Lophius Food Namibia , Lophius Reproduction Namibia , Lophius Age Namibia , Lophius Growth Namibia , Lophius Habitat Namibia , Lophius Conservation Namibia , Fisheries Namibia , Overfishing Namibia , Fishery management Namibia , Lophius vomerinus (Valenciennes, 1837) , Cape monkfish
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188329 , vital:44744 , 10.21504/10962/188329
- Description: Cape monkfish, Lophius vomerinus Valenciennes 1837, has supported the Namibian fishing industry for decades, historically as by-catch and recently as a target species. This species is also an important predator in this region. With increasing levels of exploitation and unprecedented climate change, an understanding of the changes in the long-term biological parameters of this species is critical. To date, there has been a scarcity of spatio-temporal studies that have examined and compared the biological aspects of Cape monkfish in relation to climate change and exploitation pressure. Investigations into changes in feeding habits, reproduction strategy, age and growth can provide valuable information for the sustainable management and conservation of this species. This thesis aimed to improve our understanding of the impacts of exploitation and climate variability on the biological parameters of Cape monkfish in the Namibian marine waters, thereby contributing to efforts directed at sustainable harvest and management of this resource. This was achieved through temporal and spatial comparisons of feeding, reproductive scope, age and growth, and catch statistics. The study used data collected during the monkfish swept-area biomass surveys of 2001–2005 and for 2007–2018, hake (deep-water hake Merluccius paradoxus Franca 1960 and shallow-water hake M. capensis Castelnau 1861) swept-area biomass surveys of 2017 and 2019, port sampling programme data collected from April 2014 to December 2019, and monkfish commercial fishing activities collected between April 2001 and December 2019. Based on historical feeding data (1986 – 1987) and contemporary feeding data (2015-2018), Cape monkfish feeds on a variety of prey species from seven groups: Teleost, Cephalopoda, Crustacea, Echinoidea, Elasmobranchii, Gastropod and Porifera. The diet was characterised by a high prevalence of empty stomachs (43.9%), showing low feeding intensity, but most prevalent in juveniles (52.9%). Although the diet composition varied at different life stages, Teleosts (especially deep-water hake Merluccius paradoxus Franca 1960) were the main constituents of the diet for all size classes as per the Index of Relative Importance (%IRI). The results highlight the particular importance of the deep-water hake M. paradoxus (by %IRI) in the diet of Cape monkfish across all size classes. There is a clear dominance of hake in both studies, which means that any overexploitation or climate-driven population decline in hake will most likely have an impact on Cape monkfish. Feeding composition was dependent on the season (p < 0.05), with the type and quantity of prey ingested changing seasonally, showing the ability of Cape monkfish to adjust its diet, depending on possible environmental parameters which consequently influence prey availability. In general, the spatial and temporal variability of the main prey items suggests that the species is highly opportunistic with a broad trophic adaptability. Comparison of historical and contemporary stomach content data indicates that Cape monkfish appear to have changed their diet, probably reflecting the availability of forage species over time and space, possibly due to climate change, fishing pressure, or both. The broad trophic adaptability for Cape monkfish highlights their adaptive potential to increasing anthropogenic stressors such as climate change. However, the dominance of the commercially important deep-water hake, M. paradoxus, in the diet during contemporary times highlights that complex trophic interactions may play a role in altering the northern Benguela fisheries. The general male to female sex ratio was measured at 1:1.67, with significant variation across depth, size class, and year (p < 0.05). Comparison of length at 50% maturity (L50) for Cape monkfish between historical (2004–2006) and contemporary time (2015–2019) showed no significant differences in both sexes, with no significant changes in the L50 for females (χ2 = 1.53, df = 1, p = 0.2154), and males (χ2 = 0.41, df = 1, p = 0.5204) between the two periods. The monthly gonadosomatic index (GSI) showed that Cape monkfish spawn throughout the year with peaks between July and September for females and August for males, similar to those observed 20 years ago. Spawning hotspot areas were identified and were consistently located between 22⁰ and 25⁰S in deeper water (> 250 m) for the 2001–2018 time series. Comparison of the contemporary (2015–2019) proportions of developing, ripe and spent gonads to the historical study data (1996 – 2000) show minimal differences. Ripe ovaries capable of spawning (Stage IV) were dominant in July (23.8%) and August (26.2%), while ripe testes were prevalent in April (52.5%) and November (28.5%). The discovery of the veil (a gelatinous, flat ribbon structure containing individual eggs) off Namibia for the first time (during this study) is a significant because this result provides important reproduction activities information of this species, which were never recorded off Namibia. The location where the veil was discovered, off Swakopmund (22⁰30'S, 13⁰25'E), provides further evidence of the identified spawning hotspot areas, this location is also identified as a monkfish consecutive hotspot fishing area. The ages, growth rates, and length-weight relationships were compared between fish collected during monkfish commercial fishing activities between 1996 and 1998 (Period 1) and during monkfish routine monitoring surveys from 2014 to 2016 (Period 2). A total of 607 (size range: 9–96 cm total length (TL)) and 852 (size range: 9–96 cm TL) Cape monkfish were aged by reading sectioned illicia, during Periods 1 and 2, respectively. The length-weight relationships were W = 0.012L3.035 (r2 = 0.98) and W = 0.014L 2.989 (r2 = 0.98) for females and males, respectively, during Period 1, and W = 0.01L2.97 (r2 = 0.98) and W = 0.01L 3.03 (r2 = 0.98) for females and males, respectively, in Period 2. The growth of Cape monkfish (in cm) for combined sexes was described by Lt = 94(1 − e(−0.10(t−(-0.31))) in Period 1 and Lt = 98(1 − e(−0.10(t−(-0.33))) in Period 2. Females grew significantly faster during Period 1 (LRT results from Maartens et al., 1999), while male and female growth was not significantly different during Period 2 (F = 0.65, p = 0.58). There were no significant differences between the male and female growth curve in Period 2 (F = 0.65, p = 0.58). Although the growth curves are similar between Period 1 and Period 2, the larger fish are in Period 2 are lighter than those in Period 1. This finding is important to the monkfish fishing industry because fish is sold by weight. This finding may suggest that although the fish grow similarly by length, changes in the environmental conditions may have resulted in a reduced condition of the fish. In terms of mean age, the historical Period 1 had a slightly lower mean age of 4.40 compared with a mean age of 5.49 during Period 2. Slight differences were also observed in the age structure between the two periods, with 2-year-olds (20.3%) the most abundant age class in the historical period while 5-year-old fish (18.3%) were most abundant in Period 2. Although the spatial distribution of the catch was not available for Period 1, 0-year-old fish were distributed from 22⁰ to 24⁰S, and 25⁰ to 26⁰S in shallower waters of 166–290 m during Period 2. Only fish between 5 and 16 years old were found off the documented historical nursery area off 28º S. The similar growth curves and spatial overlap of nursery habitats between Period 1 and Period 2 suggest that Cape monkfish may be fairly resilient to the rapid environmental change reported in this region and to the extensive levels of exploitation for the species. However, the recent spatial shifts in the nursery areas are sensitive to disturbance and may indicate that these changes could be having an impact on the early life stages of the species. Continued monitoring may be necessary to understand the consequences of these spatial shifts for the age and growth and resilience of the species. Analysis of the overall spatial and temporal catches of monkfish (both Cape monkfish and shortspine African monkfish) off Namibia between 1998 and 2018 identified noticeable spatio-temporal trends. The pattern of fishing activities for Cape monkfish is heterogeneous, with identified ‘hotspots’ in specific areas. Of particular importance is the consecutive hotspot, between 1998 to 2018 for monkfish fishing activities between 25⁰ and 26⁰ S. The kernel density analysis indicated that the area around 24⁰S, and between 26º and 27 ⁰S, between Walvis Bay and Lüderitz, had the highest total catch densities (~300 kg/km2), suggesting that this is the core of the stock abundance. Annual monkfish catches have fluctuated since the inception of the fishery in 1994, with a drastic decline in the catch recorded after 2003 through to 2018. Generally, there has been an underutilisation of the total allowable catch (TAC) for most of the years. The decrease in catches and the underutilisation of the TAC might be indicative of the reduction in the stock abundance. However, external factors such as lack of capacity of the fishing industry and the administration can contribute to underutilisation of TAC. Basic regression analysis between total monthly catches and monthly sea surface temperature (SST) yielded low r-squared values indicate that in all three grids, only ~ 1% of the variation is explained between SST and total monkfish catches in these areas. The most prominent points to consider from this study are the results of the comparative feeding study (Chapter 3), reproductive indicators (Chapter 4) and age and growth (Chapter 5). Certainly, there have been changes in feeding, demography, and distribution of the species in the last two decades – climate-driven changes were recorded in the feeding habits of Cape monkfish, spatially and temporally – but despite the changes in prey species composition, distribution and abundance in various habits and periods, Cape monkfish was able to switch prey species, reflecting wide trophic adaptability. The dominance of M. paradoxus at all size classes in all analysed habitats is a significant result because. The peak spawning period has remained the same between July and September, as previously reported in Period 1. The consecutive spawning hotspots were identified in the areas between 22º and 25ºS. From a fisheries management perspective, the spawning ground and spawning season should be protected (by means of closure). The evidence of changes in length at 50% maturity presented in this study hints at both climate change and extensive exploitation pressure. The discovery of the veil for the first time in this study is very important; however, it might be sampling related and not driven by climate or exploitation pressure. Finally, the change in the Cape monkfish distribution discussed in Chapter 6 may be attributed to a shift in the distribution or fishing effort as a consequence of shallow water depletion. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Erasmus, Victoria Ndinelago
- Date: 2021-10-29
- Subjects: Lophius Namibia , Lophius Climatic factors Namibia , Lophius Effect of human beings on Namibia , Lophius Food Namibia , Lophius Reproduction Namibia , Lophius Age Namibia , Lophius Growth Namibia , Lophius Habitat Namibia , Lophius Conservation Namibia , Fisheries Namibia , Overfishing Namibia , Fishery management Namibia , Lophius vomerinus (Valenciennes, 1837) , Cape monkfish
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188329 , vital:44744 , 10.21504/10962/188329
- Description: Cape monkfish, Lophius vomerinus Valenciennes 1837, has supported the Namibian fishing industry for decades, historically as by-catch and recently as a target species. This species is also an important predator in this region. With increasing levels of exploitation and unprecedented climate change, an understanding of the changes in the long-term biological parameters of this species is critical. To date, there has been a scarcity of spatio-temporal studies that have examined and compared the biological aspects of Cape monkfish in relation to climate change and exploitation pressure. Investigations into changes in feeding habits, reproduction strategy, age and growth can provide valuable information for the sustainable management and conservation of this species. This thesis aimed to improve our understanding of the impacts of exploitation and climate variability on the biological parameters of Cape monkfish in the Namibian marine waters, thereby contributing to efforts directed at sustainable harvest and management of this resource. This was achieved through temporal and spatial comparisons of feeding, reproductive scope, age and growth, and catch statistics. The study used data collected during the monkfish swept-area biomass surveys of 2001–2005 and for 2007–2018, hake (deep-water hake Merluccius paradoxus Franca 1960 and shallow-water hake M. capensis Castelnau 1861) swept-area biomass surveys of 2017 and 2019, port sampling programme data collected from April 2014 to December 2019, and monkfish commercial fishing activities collected between April 2001 and December 2019. Based on historical feeding data (1986 – 1987) and contemporary feeding data (2015-2018), Cape monkfish feeds on a variety of prey species from seven groups: Teleost, Cephalopoda, Crustacea, Echinoidea, Elasmobranchii, Gastropod and Porifera. The diet was characterised by a high prevalence of empty stomachs (43.9%), showing low feeding intensity, but most prevalent in juveniles (52.9%). Although the diet composition varied at different life stages, Teleosts (especially deep-water hake Merluccius paradoxus Franca 1960) were the main constituents of the diet for all size classes as per the Index of Relative Importance (%IRI). The results highlight the particular importance of the deep-water hake M. paradoxus (by %IRI) in the diet of Cape monkfish across all size classes. There is a clear dominance of hake in both studies, which means that any overexploitation or climate-driven population decline in hake will most likely have an impact on Cape monkfish. Feeding composition was dependent on the season (p < 0.05), with the type and quantity of prey ingested changing seasonally, showing the ability of Cape monkfish to adjust its diet, depending on possible environmental parameters which consequently influence prey availability. In general, the spatial and temporal variability of the main prey items suggests that the species is highly opportunistic with a broad trophic adaptability. Comparison of historical and contemporary stomach content data indicates that Cape monkfish appear to have changed their diet, probably reflecting the availability of forage species over time and space, possibly due to climate change, fishing pressure, or both. The broad trophic adaptability for Cape monkfish highlights their adaptive potential to increasing anthropogenic stressors such as climate change. However, the dominance of the commercially important deep-water hake, M. paradoxus, in the diet during contemporary times highlights that complex trophic interactions may play a role in altering the northern Benguela fisheries. The general male to female sex ratio was measured at 1:1.67, with significant variation across depth, size class, and year (p < 0.05). Comparison of length at 50% maturity (L50) for Cape monkfish between historical (2004–2006) and contemporary time (2015–2019) showed no significant differences in both sexes, with no significant changes in the L50 for females (χ2 = 1.53, df = 1, p = 0.2154), and males (χ2 = 0.41, df = 1, p = 0.5204) between the two periods. The monthly gonadosomatic index (GSI) showed that Cape monkfish spawn throughout the year with peaks between July and September for females and August for males, similar to those observed 20 years ago. Spawning hotspot areas were identified and were consistently located between 22⁰ and 25⁰S in deeper water (> 250 m) for the 2001–2018 time series. Comparison of the contemporary (2015–2019) proportions of developing, ripe and spent gonads to the historical study data (1996 – 2000) show minimal differences. Ripe ovaries capable of spawning (Stage IV) were dominant in July (23.8%) and August (26.2%), while ripe testes were prevalent in April (52.5%) and November (28.5%). The discovery of the veil (a gelatinous, flat ribbon structure containing individual eggs) off Namibia for the first time (during this study) is a significant because this result provides important reproduction activities information of this species, which were never recorded off Namibia. The location where the veil was discovered, off Swakopmund (22⁰30'S, 13⁰25'E), provides further evidence of the identified spawning hotspot areas, this location is also identified as a monkfish consecutive hotspot fishing area. The ages, growth rates, and length-weight relationships were compared between fish collected during monkfish commercial fishing activities between 1996 and 1998 (Period 1) and during monkfish routine monitoring surveys from 2014 to 2016 (Period 2). A total of 607 (size range: 9–96 cm total length (TL)) and 852 (size range: 9–96 cm TL) Cape monkfish were aged by reading sectioned illicia, during Periods 1 and 2, respectively. The length-weight relationships were W = 0.012L3.035 (r2 = 0.98) and W = 0.014L 2.989 (r2 = 0.98) for females and males, respectively, during Period 1, and W = 0.01L2.97 (r2 = 0.98) and W = 0.01L 3.03 (r2 = 0.98) for females and males, respectively, in Period 2. The growth of Cape monkfish (in cm) for combined sexes was described by Lt = 94(1 − e(−0.10(t−(-0.31))) in Period 1 and Lt = 98(1 − e(−0.10(t−(-0.33))) in Period 2. Females grew significantly faster during Period 1 (LRT results from Maartens et al., 1999), while male and female growth was not significantly different during Period 2 (F = 0.65, p = 0.58). There were no significant differences between the male and female growth curve in Period 2 (F = 0.65, p = 0.58). Although the growth curves are similar between Period 1 and Period 2, the larger fish are in Period 2 are lighter than those in Period 1. This finding is important to the monkfish fishing industry because fish is sold by weight. This finding may suggest that although the fish grow similarly by length, changes in the environmental conditions may have resulted in a reduced condition of the fish. In terms of mean age, the historical Period 1 had a slightly lower mean age of 4.40 compared with a mean age of 5.49 during Period 2. Slight differences were also observed in the age structure between the two periods, with 2-year-olds (20.3%) the most abundant age class in the historical period while 5-year-old fish (18.3%) were most abundant in Period 2. Although the spatial distribution of the catch was not available for Period 1, 0-year-old fish were distributed from 22⁰ to 24⁰S, and 25⁰ to 26⁰S in shallower waters of 166–290 m during Period 2. Only fish between 5 and 16 years old were found off the documented historical nursery area off 28º S. The similar growth curves and spatial overlap of nursery habitats between Period 1 and Period 2 suggest that Cape monkfish may be fairly resilient to the rapid environmental change reported in this region and to the extensive levels of exploitation for the species. However, the recent spatial shifts in the nursery areas are sensitive to disturbance and may indicate that these changes could be having an impact on the early life stages of the species. Continued monitoring may be necessary to understand the consequences of these spatial shifts for the age and growth and resilience of the species. Analysis of the overall spatial and temporal catches of monkfish (both Cape monkfish and shortspine African monkfish) off Namibia between 1998 and 2018 identified noticeable spatio-temporal trends. The pattern of fishing activities for Cape monkfish is heterogeneous, with identified ‘hotspots’ in specific areas. Of particular importance is the consecutive hotspot, between 1998 to 2018 for monkfish fishing activities between 25⁰ and 26⁰ S. The kernel density analysis indicated that the area around 24⁰S, and between 26º and 27 ⁰S, between Walvis Bay and Lüderitz, had the highest total catch densities (~300 kg/km2), suggesting that this is the core of the stock abundance. Annual monkfish catches have fluctuated since the inception of the fishery in 1994, with a drastic decline in the catch recorded after 2003 through to 2018. Generally, there has been an underutilisation of the total allowable catch (TAC) for most of the years. The decrease in catches and the underutilisation of the TAC might be indicative of the reduction in the stock abundance. However, external factors such as lack of capacity of the fishing industry and the administration can contribute to underutilisation of TAC. Basic regression analysis between total monthly catches and monthly sea surface temperature (SST) yielded low r-squared values indicate that in all three grids, only ~ 1% of the variation is explained between SST and total monkfish catches in these areas. The most prominent points to consider from this study are the results of the comparative feeding study (Chapter 3), reproductive indicators (Chapter 4) and age and growth (Chapter 5). Certainly, there have been changes in feeding, demography, and distribution of the species in the last two decades – climate-driven changes were recorded in the feeding habits of Cape monkfish, spatially and temporally – but despite the changes in prey species composition, distribution and abundance in various habits and periods, Cape monkfish was able to switch prey species, reflecting wide trophic adaptability. The dominance of M. paradoxus at all size classes in all analysed habitats is a significant result because. The peak spawning period has remained the same between July and September, as previously reported in Period 1. The consecutive spawning hotspots were identified in the areas between 22º and 25ºS. From a fisheries management perspective, the spawning ground and spawning season should be protected (by means of closure). The evidence of changes in length at 50% maturity presented in this study hints at both climate change and extensive exploitation pressure. The discovery of the veil for the first time in this study is very important; however, it might be sampling related and not driven by climate or exploitation pressure. Finally, the change in the Cape monkfish distribution discussed in Chapter 6 may be attributed to a shift in the distribution or fishing effort as a consequence of shallow water depletion. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
Impact of press freedom on reportage of corruption in the Nigerian oil and gas industry : a comparative content analysis of four Nigerian Newspapers
- Ayodeji-Falade, Monisola Bolajoko
- Authors: Ayodeji-Falade, Monisola Bolajoko
- Date: 2021-10
- Subjects: Newspapers -- Nigeria , Freedom of the press , Mass media -- Nigeria
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21805 , vital:51787
- Description: A free press is pivotal to eradication of corruption in the society as the press remains the most powerful channel of communication that cut across all publics. Thus, this study seeks to evaluate the impact of press freedom on reportage of corruption in the oil and gas industry through a content analysis of four Nigerian newspapers (The Punch, Vanguard, Guardian and Nigerian Tribune). The study adopted a mixed research method involving both quantitative and qualitative approaches. Quantitative data were collected and analysed through content analysis of the selected newspapers while the qualitative data collected through interview of the respective newspaper correspondents were analysed using thematic analysis. The study revealed that 534 stories were published on corruption in the Nigerian oil and gas sector by all the newspapers within the study period (July 2018-June 2019), with the Punch having the highest magnitude of stories (n = 196, 36.70percent) while Nigerian Tribune had the highest number of stories reported on its front and back pages (n = 143, 92.25percent). However, Guardian had the highest number of full-paged stories (n = 15, 20percent) whereas the Punch and Nigerian Tribune adopted the widest range of publication formats with news being the most dominant format employed by all the dailies (n = 462, 86.52percent). Although, all the newspapers employed more episodic frame (n = 432, 80.89percent) than thematic frame (n = 93,17.41percent), framing analysis revealed oil theft, vandalism, alleged-fraud, environmental consequences and economic consequences as the major frames used in the coverage of stories on corruption in the Nigerian oil and gas industry. Thematic analysis showed that the newspaper correspondents did not have access to adequate information on corruption in the sector while journalists in the country are still being subjected to intimidation, arrest and imprisonment. These findings suggest that the selected newspapers gave prominence to reportage of corruption in the oil and gas sector in country, which implies that the newspapers are fulfilling their agenda-setting roles and social responsibility in the society. Nevertheless, the level of press freedom in Nigeria has partly affected the reportage of corruption in the oil and gas sector of the country as this has restricted the use of investigative reporting occasioned by the lack of access to classified information on corruption and envisaged harm by potential sources and journalists. Nevertheless, this study proposes an anticorruption-media model, which focuses on the significance of the media as an anticorruption agent in a developing country. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Ayodeji-Falade, Monisola Bolajoko
- Date: 2021-10
- Subjects: Newspapers -- Nigeria , Freedom of the press , Mass media -- Nigeria
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21805 , vital:51787
- Description: A free press is pivotal to eradication of corruption in the society as the press remains the most powerful channel of communication that cut across all publics. Thus, this study seeks to evaluate the impact of press freedom on reportage of corruption in the oil and gas industry through a content analysis of four Nigerian newspapers (The Punch, Vanguard, Guardian and Nigerian Tribune). The study adopted a mixed research method involving both quantitative and qualitative approaches. Quantitative data were collected and analysed through content analysis of the selected newspapers while the qualitative data collected through interview of the respective newspaper correspondents were analysed using thematic analysis. The study revealed that 534 stories were published on corruption in the Nigerian oil and gas sector by all the newspapers within the study period (July 2018-June 2019), with the Punch having the highest magnitude of stories (n = 196, 36.70percent) while Nigerian Tribune had the highest number of stories reported on its front and back pages (n = 143, 92.25percent). However, Guardian had the highest number of full-paged stories (n = 15, 20percent) whereas the Punch and Nigerian Tribune adopted the widest range of publication formats with news being the most dominant format employed by all the dailies (n = 462, 86.52percent). Although, all the newspapers employed more episodic frame (n = 432, 80.89percent) than thematic frame (n = 93,17.41percent), framing analysis revealed oil theft, vandalism, alleged-fraud, environmental consequences and economic consequences as the major frames used in the coverage of stories on corruption in the Nigerian oil and gas industry. Thematic analysis showed that the newspaper correspondents did not have access to adequate information on corruption in the sector while journalists in the country are still being subjected to intimidation, arrest and imprisonment. These findings suggest that the selected newspapers gave prominence to reportage of corruption in the oil and gas sector in country, which implies that the newspapers are fulfilling their agenda-setting roles and social responsibility in the society. Nevertheless, the level of press freedom in Nigeria has partly affected the reportage of corruption in the oil and gas sector of the country as this has restricted the use of investigative reporting occasioned by the lack of access to classified information on corruption and envisaged harm by potential sources and journalists. Nevertheless, this study proposes an anticorruption-media model, which focuses on the significance of the media as an anticorruption agent in a developing country. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-10
Investigating the feasibility of using remote sensing in index-based crop insurance for South Africa’s smallholder farming systems
- Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Authors: Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Date: 2021-10
- Subjects: Precision farming , Agricultural engineering , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23000 , vital:54890
- Description: Crop farming in Sub-Saharan Africa (SSA) is largely practiced by resource-poor farmers under rain-fed and unpredictable weather conditions. Since agriculture is the mainstay of SSA’s economy, the lack of improved and adapted agricultural technologies in this region sets back economic development and the fight against poverty. Overcoming this constraint and achieving the sustainable development goal to end poverty, requires innovative tools that can be used for weather risk management. One tool that has been gaining momentum recently is index-based crop insurance (IBCI). Since the launch of the first IBCI program in Africa around 2005, the number of IBCI programs has increased. Unfortunately, these programs are constrained by poor product design, basis risk, and low uptake of contracts. When these issues were first pointed-out in the earliest IBCI programs, many reports suggested satellite remote sensing (RS) as a viable solution. Hence, the first objective of this study was to assess how RS has been used in IBCI, the challenges RS faces, and potential contributions of RS that have not yet been meaningfully exploited. The literature shows that IBCI programs are increasingly adopting RS. RS has improved demarcation of unit areas of insurance and enabled IBCI to reach inaccessible areas that do not have sufficient meteorological infrastructure. However, the literature also shows that IBCI is still tainted by basis risk, which emanates from poor contract designs, the influence of non-weather factors on crop yields, imperfect correlations between satellite-based indices and crop yields, and the lack of historical data for calibration. Although IBCI reports cover vegetation and crop health monitoring, few to none cover crop type and crop area mapping. Furthermore, areas including high-resolution mapping, data fusion, microwave RS, machine learning, and computer vision have not been sufficiently tested in IBCI. The second objective of this study was to assess how RS and machine learning techniques can be used to enhance the mapping of smallholder crop farming landscapes. The findings show that machine learning ensembles and the combination of optical and microwave data can map a smallholder farming landscape with a maximum accuracy of 97.71 percent. The third objective was to identify factors that influence crop yields and crop losses in order to improve IBCI design. Results demonstrated that the pervasive notion that low yields in smallholder farms are related to rainfall is an oversimplification. Factors including fertilizer use, seed variety, soil properties, soil moisture, growing degree-days, management, and socioeconomic conditions are some of the most important factors influencing crop yields and crop losses in smallholder farming systems. This shows why IBCI needs to be part of a comprehensive risk management system that understands and approaches smallholder crop farming as complex by linking insurance with advisories and input supplies. Improved inputs and good farming practices could reduce the influence of non-weather factors on crop losses, and thereby reduce basis risk in weather-based index insurance (WII) contracts. The fourth objective of this study was to assess how well the combination of synthetic aperture radar (SAR) and optical indices estimate soil moisture. As stated earlier, soil moisture was found to be one of the most important factors affecting crop yields. Although this method better estimated soil moisture over the first half of the growing season, estimation accuracies were comparable to those found in studies that had used similar datasets (RMSE = 0.043 m3 m-3, MAE = 0.034 m3 m- 3). Further interrogation of interaction effects between the variables used in this study and consideration of other factors that affect SAR backscatter could improve the method. More importantly, incorporating high-resolution satellite-based monitoring of soil moisture into IBCI could potentially reduce basis risk. The fifth objective of this study was to develop an IBCI for smallholder crop farming systems. The proposed IBCI scheme covers maize and derives index thresholds from crop water requirements and satellite-based rainfall estimates. It covers rainfall deficits over the vegetative, mid-season, and late-season stages of maize growth. The key contribution of this system is the derivation of index thresholds from CWR and site-specific rainfall conditions. The widely used approach, which calibrates IBCI by correlating yields and rainfall, exposes contracts to basis risk because, by simply correlating yield and rainfall data, it overlooks the influence of non-weather factors on crop yields and losses. The proposed system must be linked or bundled with non-weather variables that affect crop yields. Effectively, this means that the insurance must be linked or bundled with advisories and input supplies to address the influence of non-weather factors on crop losses. This system also incorporates a crop area-mapping component, which was found to be lacking in many IBCI systems. In conclusion, an IBCI that is based on crop water requirements, which incorporates crop area mapping and links insurance with non-weather crop yield-determining factors, is potentially capable of improving crop insurance for smallholder farming systems. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Date: 2021-10
- Subjects: Precision farming , Agricultural engineering , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23000 , vital:54890
- Description: Crop farming in Sub-Saharan Africa (SSA) is largely practiced by resource-poor farmers under rain-fed and unpredictable weather conditions. Since agriculture is the mainstay of SSA’s economy, the lack of improved and adapted agricultural technologies in this region sets back economic development and the fight against poverty. Overcoming this constraint and achieving the sustainable development goal to end poverty, requires innovative tools that can be used for weather risk management. One tool that has been gaining momentum recently is index-based crop insurance (IBCI). Since the launch of the first IBCI program in Africa around 2005, the number of IBCI programs has increased. Unfortunately, these programs are constrained by poor product design, basis risk, and low uptake of contracts. When these issues were first pointed-out in the earliest IBCI programs, many reports suggested satellite remote sensing (RS) as a viable solution. Hence, the first objective of this study was to assess how RS has been used in IBCI, the challenges RS faces, and potential contributions of RS that have not yet been meaningfully exploited. The literature shows that IBCI programs are increasingly adopting RS. RS has improved demarcation of unit areas of insurance and enabled IBCI to reach inaccessible areas that do not have sufficient meteorological infrastructure. However, the literature also shows that IBCI is still tainted by basis risk, which emanates from poor contract designs, the influence of non-weather factors on crop yields, imperfect correlations between satellite-based indices and crop yields, and the lack of historical data for calibration. Although IBCI reports cover vegetation and crop health monitoring, few to none cover crop type and crop area mapping. Furthermore, areas including high-resolution mapping, data fusion, microwave RS, machine learning, and computer vision have not been sufficiently tested in IBCI. The second objective of this study was to assess how RS and machine learning techniques can be used to enhance the mapping of smallholder crop farming landscapes. The findings show that machine learning ensembles and the combination of optical and microwave data can map a smallholder farming landscape with a maximum accuracy of 97.71 percent. The third objective was to identify factors that influence crop yields and crop losses in order to improve IBCI design. Results demonstrated that the pervasive notion that low yields in smallholder farms are related to rainfall is an oversimplification. Factors including fertilizer use, seed variety, soil properties, soil moisture, growing degree-days, management, and socioeconomic conditions are some of the most important factors influencing crop yields and crop losses in smallholder farming systems. This shows why IBCI needs to be part of a comprehensive risk management system that understands and approaches smallholder crop farming as complex by linking insurance with advisories and input supplies. Improved inputs and good farming practices could reduce the influence of non-weather factors on crop losses, and thereby reduce basis risk in weather-based index insurance (WII) contracts. The fourth objective of this study was to assess how well the combination of synthetic aperture radar (SAR) and optical indices estimate soil moisture. As stated earlier, soil moisture was found to be one of the most important factors affecting crop yields. Although this method better estimated soil moisture over the first half of the growing season, estimation accuracies were comparable to those found in studies that had used similar datasets (RMSE = 0.043 m3 m-3, MAE = 0.034 m3 m- 3). Further interrogation of interaction effects between the variables used in this study and consideration of other factors that affect SAR backscatter could improve the method. More importantly, incorporating high-resolution satellite-based monitoring of soil moisture into IBCI could potentially reduce basis risk. The fifth objective of this study was to develop an IBCI for smallholder crop farming systems. The proposed IBCI scheme covers maize and derives index thresholds from crop water requirements and satellite-based rainfall estimates. It covers rainfall deficits over the vegetative, mid-season, and late-season stages of maize growth. The key contribution of this system is the derivation of index thresholds from CWR and site-specific rainfall conditions. The widely used approach, which calibrates IBCI by correlating yields and rainfall, exposes contracts to basis risk because, by simply correlating yield and rainfall data, it overlooks the influence of non-weather factors on crop yields and losses. The proposed system must be linked or bundled with non-weather variables that affect crop yields. Effectively, this means that the insurance must be linked or bundled with advisories and input supplies to address the influence of non-weather factors on crop losses. This system also incorporates a crop area-mapping component, which was found to be lacking in many IBCI systems. In conclusion, an IBCI that is based on crop water requirements, which incorporates crop area mapping and links insurance with non-weather crop yield-determining factors, is potentially capable of improving crop insurance for smallholder farming systems. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
Rethinking the role of councilors in a digital era governance:: a critical analysis of Shinyanga Municipality and Nzega District Council in Tanzania
- Linje, Anna Peter https://orcid.org/0000-0003-1990-3309
- Authors: Linje, Anna Peter https://orcid.org/0000-0003-1990-3309
- Date: 2021-10
- Subjects: Internet in public administration , Information technology Political aspects
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21759 , vital:51749
- Description: This study endeavored to rethink the roles of councilors in a digital era governance. The essence of councils’ role according to Adams (2013), is that they are the only level of government with a legislative mandate for the well-being of people and responsive to local risks and opportunities. Therefore, it is important to rethink their roles as they require a full range of interactions which can now be facilitated by the use of digital potentials (Adams, 2013). The study explored the councilors’ undertakings to understand the current situation and if they embrace the new forms of digital governance. Also, the researcher reviewed the laws and policies guiding the councilors in their undertakings and if they accommodated the digital era requirements. Moreover, the researcher examined the capacity of councilors and the challenges they face in their undertakings. The study employed a qualitative approach, whereby semistructured interviews, observation and documentary review were used to collect data. The findings revealed that councils’ practices and processes continue to be outside the digital age. One of the major factors was a dearth of limited practical experiences to upkeep the digital governance opportunities and tailor their decisions accordingly. Regarding legislatives, the findings showed that there was evidence of formulation of new legislatives including the current ICT policy (2016) that respond to the digital governance. Yet, it was indicated that the digital legislatives were not well captured by the individual councilors, while the enforcement mechanisms were still at its infancy. Also, councils could not provide a clear digital platform framework. The capacity of councilors was found to be insufficient, they were not well equipped in terms of facilities, skills and digital technicalities. Generally, lack of political readiness, spirit of fear and poor digital infrastructure were major challenges. The study recommended councils adopt new ways in parallel with the existing ones, this should be inclusive of frequent trainings. , Thesis (PhD) -- Faculty of Management and Commerce, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Linje, Anna Peter https://orcid.org/0000-0003-1990-3309
- Date: 2021-10
- Subjects: Internet in public administration , Information technology Political aspects
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21759 , vital:51749
- Description: This study endeavored to rethink the roles of councilors in a digital era governance. The essence of councils’ role according to Adams (2013), is that they are the only level of government with a legislative mandate for the well-being of people and responsive to local risks and opportunities. Therefore, it is important to rethink their roles as they require a full range of interactions which can now be facilitated by the use of digital potentials (Adams, 2013). The study explored the councilors’ undertakings to understand the current situation and if they embrace the new forms of digital governance. Also, the researcher reviewed the laws and policies guiding the councilors in their undertakings and if they accommodated the digital era requirements. Moreover, the researcher examined the capacity of councilors and the challenges they face in their undertakings. The study employed a qualitative approach, whereby semistructured interviews, observation and documentary review were used to collect data. The findings revealed that councils’ practices and processes continue to be outside the digital age. One of the major factors was a dearth of limited practical experiences to upkeep the digital governance opportunities and tailor their decisions accordingly. Regarding legislatives, the findings showed that there was evidence of formulation of new legislatives including the current ICT policy (2016) that respond to the digital governance. Yet, it was indicated that the digital legislatives were not well captured by the individual councilors, while the enforcement mechanisms were still at its infancy. Also, councils could not provide a clear digital platform framework. The capacity of councilors was found to be insufficient, they were not well equipped in terms of facilities, skills and digital technicalities. Generally, lack of political readiness, spirit of fear and poor digital infrastructure were major challenges. The study recommended councils adopt new ways in parallel with the existing ones, this should be inclusive of frequent trainings. , Thesis (PhD) -- Faculty of Management and Commerce, 2021
- Full Text:
- Date Issued: 2021-10
Access to justice for female victims of crime: a study of girls and women with disabilities in Mashonaland Central Province of Zimbabwe
- Authors: Shumba, Nyaradzo Dorcas
- Date: 2021-09
- Subjects: Criminal justice, Administration of -- Zimbabwe , Women -- Crimes against , Victims of crimes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22176 , vital:51994
- Description: This thesis utilized a thematic content analysis, looked at how significant barriers affect Mashonaland Central girls and women living with disabilities as victims of crime from accessing justice. Zimbabwe is an optimal case to apply this study, due to its contradictory legislation and evidence of high rate of human rights violations. Mashonaland Central Province is an ideal case study due to the extant records that indicate that it has the highest incidences of violence against women. This study is therefore based in a Victimological epoch with the aim to fill the research gap in acknowledging the process of accessing justice as an important step for protecting and promoting human right. By analyzing interviews conducted with 3 different women aged 18-65 and 3 girls living with disability who were under the age of 18, through the theoretical framework of basic human rights theory and victim dynamics, this thesis contributes to the existing body of knowledge, with suggestions of how these barriers which are inclusive of societal and cultural structures tend to affect the respondents’ everyday lives and in a most pertinent manner towards their right to access justice. This thesis is also governed by the perspectives of key actors in the judicial process including but not limited to the Victim Friendly Unit. The theoretical framework is also operationalized into themes and criteria, which are then applied to analyze the conducted interviews. The emerging findings illuminate that there is a discrepancy between government policy surrounding girls and women living with disabilities and the practical experiences of the respondents. The respondents experienced a lack of accessibility to basic rights such as health care, the law, and to sex education – which are all rights ensured by government policy. Identified consequences included: discouragement in seeking justice due to fears of cultural and social stigma, discouragement in reporting crimes, and receiving adequate support, as well as information from secondhand sources. This study therefore concludes lack of access to justice is a violation of security of person, human dignity and rights to health and life to women and girls living with disability. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Shumba, Nyaradzo Dorcas
- Date: 2021-09
- Subjects: Criminal justice, Administration of -- Zimbabwe , Women -- Crimes against , Victims of crimes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22176 , vital:51994
- Description: This thesis utilized a thematic content analysis, looked at how significant barriers affect Mashonaland Central girls and women living with disabilities as victims of crime from accessing justice. Zimbabwe is an optimal case to apply this study, due to its contradictory legislation and evidence of high rate of human rights violations. Mashonaland Central Province is an ideal case study due to the extant records that indicate that it has the highest incidences of violence against women. This study is therefore based in a Victimological epoch with the aim to fill the research gap in acknowledging the process of accessing justice as an important step for protecting and promoting human right. By analyzing interviews conducted with 3 different women aged 18-65 and 3 girls living with disability who were under the age of 18, through the theoretical framework of basic human rights theory and victim dynamics, this thesis contributes to the existing body of knowledge, with suggestions of how these barriers which are inclusive of societal and cultural structures tend to affect the respondents’ everyday lives and in a most pertinent manner towards their right to access justice. This thesis is also governed by the perspectives of key actors in the judicial process including but not limited to the Victim Friendly Unit. The theoretical framework is also operationalized into themes and criteria, which are then applied to analyze the conducted interviews. The emerging findings illuminate that there is a discrepancy between government policy surrounding girls and women living with disabilities and the practical experiences of the respondents. The respondents experienced a lack of accessibility to basic rights such as health care, the law, and to sex education – which are all rights ensured by government policy. Identified consequences included: discouragement in seeking justice due to fears of cultural and social stigma, discouragement in reporting crimes, and receiving adequate support, as well as information from secondhand sources. This study therefore concludes lack of access to justice is a violation of security of person, human dignity and rights to health and life to women and girls living with disability. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-09
Compartmentalization of mineral elements, nutritional factors, biological potentials and phytochemical profiles in the fruits of Musa sinensis L.(Banana) and Musa paradisiaca L.(Plantain): A comparison among soft flesh, peel and boiled peel extract
- Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Conflict-induced displacement: a study of risk and support for the older refugees in South Africa
- Yusuf, Mohammed Sanusi https://orcid.org/0000-0002-6871-0186
- Authors: Yusuf, Mohammed Sanusi https://orcid.org/0000-0002-6871-0186
- Date: 2021-09
- Subjects: Migration, Internal , Displacement (Psychology) , Refugees -- Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22231 , vital:52001
- Description: With the exponential rise in conflict scenarios globally, the number of internally displaced persons (IDPs) and refugees in foreign countries continues to grow. Although there has been several international efforts and conventions aimed at alleviating the global refugee crisis, the international community has not found a sustainable answer to this knotty problem. In Africa, with some of the worst conflict situations, the scourge of social displacement resulting in migrations have caused different levels of risks and vulnerability for the refugees, as well as capacity constraints for the host communities, governments of host countries and non-governmental bodies working with refugees. In South Africa, with one of the highest numbers of refugees in Africa, especially those coming from African countries, contention for socio-economic space and cultural differences occasionally result in violence between refugees and local people. For the older refugees, the level of risk exposure and hardship have generated interests for both scholars and officials. This thesis explores the risks and support systems for older refugees in South Africa, with specific focus on the Eastern Cape province. Various stakeholders (such as government, NGOs, host communities and the older refugees) in refugee management in South Africa have argued differently on ‘how best’ to manage older refugees in the country. Using qualitative data gathered from refugee communities in the Eastern Cape province and documentary analysis, the study found that the experiences of older refugees in the Eastern Cape province are nuanced. The dominant narrative on the experiences of older refugees indicate peaceful coexistence and resilient organic community support systems, with minor conflicts – often associated with contestations for scarce economic opportunities. Although the study focuses on one province of South Africa, this finding challenges the often-overgeneralised perception of South Africa as ‘xenophobic’. It unpacks the hidden resilient social systems and networks of relationships that bind local populations and the refugees, especially the older ones. In the search for national, regional and global answers on the best way to manage refugee crisis, this study provides insights into community-level structures and dynamics that would benefit policymaking at the national and international levels , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Yusuf, Mohammed Sanusi https://orcid.org/0000-0002-6871-0186
- Date: 2021-09
- Subjects: Migration, Internal , Displacement (Psychology) , Refugees -- Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22231 , vital:52001
- Description: With the exponential rise in conflict scenarios globally, the number of internally displaced persons (IDPs) and refugees in foreign countries continues to grow. Although there has been several international efforts and conventions aimed at alleviating the global refugee crisis, the international community has not found a sustainable answer to this knotty problem. In Africa, with some of the worst conflict situations, the scourge of social displacement resulting in migrations have caused different levels of risks and vulnerability for the refugees, as well as capacity constraints for the host communities, governments of host countries and non-governmental bodies working with refugees. In South Africa, with one of the highest numbers of refugees in Africa, especially those coming from African countries, contention for socio-economic space and cultural differences occasionally result in violence between refugees and local people. For the older refugees, the level of risk exposure and hardship have generated interests for both scholars and officials. This thesis explores the risks and support systems for older refugees in South Africa, with specific focus on the Eastern Cape province. Various stakeholders (such as government, NGOs, host communities and the older refugees) in refugee management in South Africa have argued differently on ‘how best’ to manage older refugees in the country. Using qualitative data gathered from refugee communities in the Eastern Cape province and documentary analysis, the study found that the experiences of older refugees in the Eastern Cape province are nuanced. The dominant narrative on the experiences of older refugees indicate peaceful coexistence and resilient organic community support systems, with minor conflicts – often associated with contestations for scarce economic opportunities. Although the study focuses on one province of South Africa, this finding challenges the often-overgeneralised perception of South Africa as ‘xenophobic’. It unpacks the hidden resilient social systems and networks of relationships that bind local populations and the refugees, especially the older ones. In the search for national, regional and global answers on the best way to manage refugee crisis, this study provides insights into community-level structures and dynamics that would benefit policymaking at the national and international levels , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-09
Determination of acaricide resistance profiles, and geographic range of boophilid Rhipicephalus tick spp. (Acari: Ixodidae), and sero-status of tick-borne pathogens on communal cattle in the north-eastern regions of the Eastern Cape Province, South Africa
- Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Authors: Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Date: 2021-09
- Subjects: Cattle -- Diseases , Ticks as carriers of disease , Ticks
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21590 , vital:49356
- Description: Cattle industry improves livelihoods for many developing farmers in South Africa, however, ticks and tick-borne diseases (TBDs) pose a detriment impact on cattle success; this is due to their resistance to acaricide application. Thus, this study was conducted to determine the extent of acaricide resistance, serostatus of tick-borne pathogens, and geographic range of boophilid ticks in communal grazing cattle in the north-eastern regions of the Eastern Cape Province (ECP), South Africa. A total of 160 structured questionnaires were prepared and randomly administered to cattle farmers to investigate their knowledge, attitudes, and practice on ticks and TBDs affecting cattle, tick control methods used, and their knowledge of acaricide resistance. Engorged visible cattle ticks were collected seasonally from 10 randomly selected cattle from the community cattle herds during dipping days between October 2018 and September 2019, and stored into the labelled test tubes containing 70 percent ethanol. For TBDs determination, a total of 240 cattle from Elundini and Senqu Municipalities were seasonally used to investigate the prevalence of ticks and TBDs, packed cell volume (PCV), and body condition scores (BCS). Shaw Larval Immersion Test (SLIT) method was used to determine the resistance of Rhipicephalus decoloratus larvae to various acaricides such as amidines, organophosphate, and synthetic pyrethroids. This study indicates that approximately 59 percent of the interviewed cattle farmers had no knowledge of the effect of TBDs affecting cattle production, and 78 percent of respondents considered ticks are the major challenge to the success of their cattle farming. Pour-on (61 percent) was the most commonly used acaricidal treatment system with fortnightly (40 percent and 31percent) treatment frequencies during the summer and winter seasons respectively. Synthetic pyrethroids (73 percent) were the most used acaricide compounds to control ticks. Moreover, approximately 85 percent of respondents perceived that they do not practice acaricide rotation, and 88 percent of the respondents had no knowledge of acaricide resistance. Interestingly, the current study record Rhipicephalus microplus for the first time at Elundini, Senqu, and Walter Sisulu. Based on the morphological traits, a total of 6176 ticks belonging to two boophilid tick species of Rhipicephalus were identified: R. decoloratus (98 percent) and R. microplus (2 percent). Rhipicephalus decoloratus was significantly higher (P<0.05) in Elundini during the hot-dry (3.37±0.121) and hot-wet (3.35±0.121) seasons compared to other localit ies. In Senqu, R. microplus had high counts (P<0.05) during the post-rainy season (1.06±0.027) compared to other localities. From this present study, it was observed that Ehrlichia ruminantium was the most prevalent at Elundini (16 percent) and (14 percent) during post-rainy and hot-dry seasons respectively and 15 percent at Senqu during the post-rainy season. Babesia bigemina was more frequent at Elundini (18 percent) and Senqu (16 percent) during the post-rainy season and hot-wet season, respectively. Cattle BCS were significantly negatively correlated with E. ruminantium (P<0.01; r = -0.203), B. bovis (P<0.01; r = -0.125), and A. marginale (P < 0.01; r = -0.122). On the other hand, PCV was significantly negatively correlated with B. bigemina (P<0.01; r =-0.138). E. ruminantium was strongly positively correlated with Amblyomma hebraeum (P<0.05; r = 0.112), while B. bovis (P<0.05; r = 0.134) and B. bigemina (P<0.05; r = 0.188) were strong positively correlated with Rhipicephalus microplus infestation and B. bigemina (P<0.05; r = 0.077) with Rhipicephalus decoloratus. During acaricide resistance testing, Shaw Larvae Immersion Testing (SLIT) was only performed on R. decoloratus larvae as engorged R. microplus ticks could not meet the required sample size for resistance testing. The current study found that the majority of the tick were susceptible at exposure to differe nt acaricide field concentrations of amidines (49 percent at 250ppm), organophosphates (33 percent and 47 percent at 300ppm and 500ppm, respectively), and synthetic pyrethroids (44 percent and 23 percent at 150ppm and 300ppm, respectively). In conclusion, less knowledge of cattle farmers on the threat pose by ticks on their cattle production results in the spatio-temporal spread of boophilid tick from region to region and from season to season thus increases incidence and risk for tick resistance. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Date: 2021-09
- Subjects: Cattle -- Diseases , Ticks as carriers of disease , Ticks
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21590 , vital:49356
- Description: Cattle industry improves livelihoods for many developing farmers in South Africa, however, ticks and tick-borne diseases (TBDs) pose a detriment impact on cattle success; this is due to their resistance to acaricide application. Thus, this study was conducted to determine the extent of acaricide resistance, serostatus of tick-borne pathogens, and geographic range of boophilid ticks in communal grazing cattle in the north-eastern regions of the Eastern Cape Province (ECP), South Africa. A total of 160 structured questionnaires were prepared and randomly administered to cattle farmers to investigate their knowledge, attitudes, and practice on ticks and TBDs affecting cattle, tick control methods used, and their knowledge of acaricide resistance. Engorged visible cattle ticks were collected seasonally from 10 randomly selected cattle from the community cattle herds during dipping days between October 2018 and September 2019, and stored into the labelled test tubes containing 70 percent ethanol. For TBDs determination, a total of 240 cattle from Elundini and Senqu Municipalities were seasonally used to investigate the prevalence of ticks and TBDs, packed cell volume (PCV), and body condition scores (BCS). Shaw Larval Immersion Test (SLIT) method was used to determine the resistance of Rhipicephalus decoloratus larvae to various acaricides such as amidines, organophosphate, and synthetic pyrethroids. This study indicates that approximately 59 percent of the interviewed cattle farmers had no knowledge of the effect of TBDs affecting cattle production, and 78 percent of respondents considered ticks are the major challenge to the success of their cattle farming. Pour-on (61 percent) was the most commonly used acaricidal treatment system with fortnightly (40 percent and 31percent) treatment frequencies during the summer and winter seasons respectively. Synthetic pyrethroids (73 percent) were the most used acaricide compounds to control ticks. Moreover, approximately 85 percent of respondents perceived that they do not practice acaricide rotation, and 88 percent of the respondents had no knowledge of acaricide resistance. Interestingly, the current study record Rhipicephalus microplus for the first time at Elundini, Senqu, and Walter Sisulu. Based on the morphological traits, a total of 6176 ticks belonging to two boophilid tick species of Rhipicephalus were identified: R. decoloratus (98 percent) and R. microplus (2 percent). Rhipicephalus decoloratus was significantly higher (P<0.05) in Elundini during the hot-dry (3.37±0.121) and hot-wet (3.35±0.121) seasons compared to other localit ies. In Senqu, R. microplus had high counts (P<0.05) during the post-rainy season (1.06±0.027) compared to other localities. From this present study, it was observed that Ehrlichia ruminantium was the most prevalent at Elundini (16 percent) and (14 percent) during post-rainy and hot-dry seasons respectively and 15 percent at Senqu during the post-rainy season. Babesia bigemina was more frequent at Elundini (18 percent) and Senqu (16 percent) during the post-rainy season and hot-wet season, respectively. Cattle BCS were significantly negatively correlated with E. ruminantium (P<0.01; r = -0.203), B. bovis (P<0.01; r = -0.125), and A. marginale (P < 0.01; r = -0.122). On the other hand, PCV was significantly negatively correlated with B. bigemina (P<0.01; r =-0.138). E. ruminantium was strongly positively correlated with Amblyomma hebraeum (P<0.05; r = 0.112), while B. bovis (P<0.05; r = 0.134) and B. bigemina (P<0.05; r = 0.188) were strong positively correlated with Rhipicephalus microplus infestation and B. bigemina (P<0.05; r = 0.077) with Rhipicephalus decoloratus. During acaricide resistance testing, Shaw Larvae Immersion Testing (SLIT) was only performed on R. decoloratus larvae as engorged R. microplus ticks could not meet the required sample size for resistance testing. The current study found that the majority of the tick were susceptible at exposure to differe nt acaricide field concentrations of amidines (49 percent at 250ppm), organophosphates (33 percent and 47 percent at 300ppm and 500ppm, respectively), and synthetic pyrethroids (44 percent and 23 percent at 150ppm and 300ppm, respectively). In conclusion, less knowledge of cattle farmers on the threat pose by ticks on their cattle production results in the spatio-temporal spread of boophilid tick from region to region and from season to season thus increases incidence and risk for tick resistance. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09