Fishing for resilience : herbivore and algal dynamics on coral reefs in Kenya.
- Authors: Humphries, Austin Turner
- Date: 2014
- Subjects: Coral reef conservation -- Kenya , Coral reef ecology -- Kenya , Coral reef biology -- Kenya , Coral reef fishes -- Kenya , Herbivores -- Kenya , Algae -- Control -- Kenya , Fishery management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5877 , http://hdl.handle.net/10962/d1013147
- Description: Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
- Full Text:
- Authors: Humphries, Austin Turner
- Date: 2014
- Subjects: Coral reef conservation -- Kenya , Coral reef ecology -- Kenya , Coral reef biology -- Kenya , Coral reef fishes -- Kenya , Herbivores -- Kenya , Algae -- Control -- Kenya , Fishery management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5877 , http://hdl.handle.net/10962/d1013147
- Description: Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
- Full Text:
Food security in a perfect storm: using the ecosystem services framework to increase understanding
- Poppy, G M, Chiotha, S, Eigenbrod, Felix, Harvey, C A, Honzák, M, Hudson, M D, Jarvis, A, Madise, N J, Schreckenberg, Kate, Shackleton, Charlie M, Villa, F, Dawson, T P
- Authors: Poppy, G M , Chiotha, S , Eigenbrod, Felix , Harvey, C A , Honzák, M , Hudson, M D , Jarvis, A , Madise, N J , Schreckenberg, Kate , Shackleton, Charlie M , Villa, F , Dawson, T P
- Date: 2014
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60952 , vital:27900 , http://dx.doi.org/10.1098/rstb.2012.0288
- Description: Achieving food security in a ‘perfect storm’ scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.
- Full Text:
- Authors: Poppy, G M , Chiotha, S , Eigenbrod, Felix , Harvey, C A , Honzák, M , Hudson, M D , Jarvis, A , Madise, N J , Schreckenberg, Kate , Shackleton, Charlie M , Villa, F , Dawson, T P
- Date: 2014
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60952 , vital:27900 , http://dx.doi.org/10.1098/rstb.2012.0288
- Description: Achieving food security in a ‘perfect storm’ scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.
- Full Text:
Formalisation, informalisation and the labour process within the minibus taxi industry in East London, South Africa
- Fobosi, Siyabulela Christopher
- Authors: Fobosi, Siyabulela Christopher
- Date: 2014
- Subjects: Taxicab industry -- South Africa -- East London , Taxicab industry -- South Africa -- East London -- Personnel management , Informal sector (Economics) -- South Africa -- East London , Economics -- Sociological aspects , Industrial relations -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3367 , http://hdl.handle.net/10962/d1012076 , Taxicab industry -- South Africa -- East London , Taxicab industry -- South Africa -- East London -- Personnel management , Informal sector (Economics) -- South Africa -- East London , Economics -- Sociological aspects , Industrial relations -- South Africa -- East London
- Description: This thesis focuses on the labour process within the minibus taxi industry in East London, South Africa. This industry is structurally situated within the informal sector or economy but is marked by contradictory processes of formalisation and in-formalisation. Though the taxi industry seems to straddle the formal and informal economies in South Africa, the study is conceptually framed in terms of the informal sector but in a critically-engaged fashion. The very distinction between formal and informal economies, whether in South Africa or elsewhere, is open to dispute; and, even if accepted, there are differing conceptualisations of the relationship between the ‘two’ economies. Also, the conceptual clarity of the term ‘informal economy’ has been subject to scrutiny, given the vast range of activities it is said to incorporate. While the distinction between formal and informal economies may be a useful conceptual starting-point, this thesis demonstrates that it is analytically useful to speak of degrees and forms of formalisation and in-formalisation along a continuum, rather than to dichotomize economies. The thesis therefore analyses in depth the competing and tension-riddled processes of formalisation and in-formalisation in the minibus taxi industry, and with a specific focus on the labour process.
- Full Text:
- Authors: Fobosi, Siyabulela Christopher
- Date: 2014
- Subjects: Taxicab industry -- South Africa -- East London , Taxicab industry -- South Africa -- East London -- Personnel management , Informal sector (Economics) -- South Africa -- East London , Economics -- Sociological aspects , Industrial relations -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3367 , http://hdl.handle.net/10962/d1012076 , Taxicab industry -- South Africa -- East London , Taxicab industry -- South Africa -- East London -- Personnel management , Informal sector (Economics) -- South Africa -- East London , Economics -- Sociological aspects , Industrial relations -- South Africa -- East London
- Description: This thesis focuses on the labour process within the minibus taxi industry in East London, South Africa. This industry is structurally situated within the informal sector or economy but is marked by contradictory processes of formalisation and in-formalisation. Though the taxi industry seems to straddle the formal and informal economies in South Africa, the study is conceptually framed in terms of the informal sector but in a critically-engaged fashion. The very distinction between formal and informal economies, whether in South Africa or elsewhere, is open to dispute; and, even if accepted, there are differing conceptualisations of the relationship between the ‘two’ economies. Also, the conceptual clarity of the term ‘informal economy’ has been subject to scrutiny, given the vast range of activities it is said to incorporate. While the distinction between formal and informal economies may be a useful conceptual starting-point, this thesis demonstrates that it is analytically useful to speak of degrees and forms of formalisation and in-formalisation along a continuum, rather than to dichotomize economies. The thesis therefore analyses in depth the competing and tension-riddled processes of formalisation and in-formalisation in the minibus taxi industry, and with a specific focus on the labour process.
- Full Text:
Formulation, development and assessment of efavirenz-loaded lipid nanocarriers
- Authors: Makoni, Pedzisai Anotida
- Date: 2014
- Subjects: Nanomedicine , Drug delivery systems , Antiretroviral agents Psychotropic effects , AIDS dementia complex
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/209981 , vital:47448
- Description: The feasibility of incorporating efavirenz (EFV) into innovative solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) using the hot high-pressure homogenization (HHPH) technique was investigated in an attempt to address the shortcomings in therapy associated with the use of conventional dosage forms. The shortcomings include the unpalatable taste of API in solution, instability in the presence of light when in solution and psychiatric side effects of the API. In particular, sustained release approaches may reduce or limit the incidence of adverse psychiatric effects of EFV and alleviate Acquired Immune Deficiency Syndrome (AIDS)-related complications such as AIDS Dementia Complex (ADC) in patients, ultimately improving their quality of life. Prior to initiating pre-formulation, formulation development and optimization studies of EFV-loaded SLN and/or NLC, Response Surface Methodology (RSM) in conjunction with central composite design (CCD), was used to develop and validate suitable methods for the quantitative determination of EFV in pharmaceutical formulations and for monitoring EFV release from SLN and/or NLC in vitro. Simple, accurate, precise, sensitive and stabilityindicating reversed phase-high performance liquid chromatography (RP-HPLC) methods with UV and electrochemical (EC) detection were developed, validated and optimized for in vitro analysis of EFV in formulations. On the basis of risk-to-benefit ratio the RP-HPLC method with UV detection was selected as the most suitable for the quantitative determination of EFV in pharmaceutical formulations, and was applied to in vitro release studies of EFV from SLN and/or NLC. Pre-formulation studies were undertaken to investigate the thermal stability of EFV so as to facilitate the selection of lipid excipients for the manufacture of nanocarriers, and to establish their compatibility with EFV. It was found that EFV was thermostable up to a temperature of approximately 200°C, indicating that HHPH could be used for the manufacture of EFV-loaded SLN and/or NLC. Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate and Transcutol® HP showing the best solubilizing potential for EFV. Glyceryl monostearate exists in a stable β-modification prior to exposure to heat, but exists in the α-polymorphic modification following exposure to heat. It was established that the addition of Transcutol® HP to glyceryl monostearate revealed the co-existence of the α- and β’-polymorphic modifications, thereby revealing the existence of the modifications in NLC produced from the optimum lipid combination. Furthermore, an investigation of binary mixtures of EFV/glyceryl monostearate and glyceryl monostearate/Transcutol® HP, in addition to eutectic mixtures of EFV, glyceryl monostearate and Transcutol® HP, revealed no interaction between EFV and the lipids selected for the production of the nanocarriers. Due to the significantly higher solubility of EFV in Transcutol® HP than in to glyceryl monostearate, NLC are most likely to have a higher LC and EE than SLN. In addition, the existence of both the α- and β’-polymorphic modifications in the binary mixture of the lipid implies that EFV expulsion on prolonged storage is unlikely to occur from NLC when compared to SLN. Consequently formulation development and optimization studies of SLN and NLC were performed to investigate the potential to deliver EFV from a novel technology with an appropriate LC and EE for EFV. Tween®80 was selected for use in these formulations as the use of this surfactant facilitates the targeting of nanocarriers to the CNS. RSM in conjunction with a Box-Behnken Design (BBD) was used to establish the effects of process variables, such as number of homogenization cycles and pressure, in addition to formulation variables such as amount of EFV and Tween®80 on the particle size (PS), polydispersity index (PDI), zeta potential (ZP), visual assessment (VA) and release rate (RR) of EFV after 24 hours. In addition the LC and EE, degree of crystallinity and lipid modification, shape and surface morphology of the optimized batches were investigated to ensure that EFV-loaded SLN and NLC of desirable quality were produced. On the day of manufacture the mean PS and PDI of EFV-loaded SLN was 59.00 ± 23.16 nm and 0.382 ± 0.054 respectively. The mean PS and PDI of EFV-loaded NLC was 34.73 ± 0.7709 nm and 0.394 ± 0.027 respectively. The formulations were in the nanometer range and exhibited a narrow particle size distribution, as indicated by the PDI values. The ZP values for optimized SLN and NLC generated on the day of manufacture using HPLC grade water as the dispersion medium were -32.5 ± 4.99 mV and -22.4 ± 3.72 mV respectively. In addition the optimized batches of SLN and NLC revealed a decrease in crystallinity in comparison to bulk lipid material. DSC, WAXS and FT-IR revealed that EFV was molecularly dispersed in the nanocarriers. In addition EFV-loaded SLN existed in a single α-polymorphic form, whereas EFV-loaded NLC exhibited the co-existence of α- and β’-polymorphic forms. Generally SLN and NLC were spherically shaped when viewed under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the day of manufacture the EE and LC of EFVloaded SLN was found to be 96.77 ± 0.453 % and 9.68 ± 1.772 % respectively. The EE and LC of EFV-loaded NLC was 99.93 ± 0.413 and 9.995 ± 0.672 respectively. The release profiles for the optimized formulations of SLN and NLC exhibited an initial burst release over the first 0-3 hours of testing, after which the release was sustained for up to 24 hours. The cumulative % EFV released over 24 hours was higher from SLN (91.5±3.423 %) than that observed for NLC (73.6±4.34 %). Stability studies performed for 8 weeks on the optimized batches of the SLN and the NLC were also conducted so as to ensure product quality. The formulations were assessed in terms of parameters considered benchmarks of stability, and included ZP, PS, PDI, LC and EE. Generally these parameters remained unchanged following storage for 8 weeks at 25°C/60% RH but showed considerable changes following storage for 8 weeks at 40°C/75% RH. These studies reveal that SLN and NLC when stored at 25°C/60% RH have the potential to be used as colloidal delivery systems for EFV that have the potential to protect EFV from photodegradation and sustain release into brain tissue. The latter will ultimately reduce or limit the incidence of adverse psychiatric effects and potentially alleviate AIDS-related complications such as ADC in patients with HIV/AIDS, ultimately improving their quality of life. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2014
- Full Text:
- Authors: Makoni, Pedzisai Anotida
- Date: 2014
- Subjects: Nanomedicine , Drug delivery systems , Antiretroviral agents Psychotropic effects , AIDS dementia complex
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/209981 , vital:47448
- Description: The feasibility of incorporating efavirenz (EFV) into innovative solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) using the hot high-pressure homogenization (HHPH) technique was investigated in an attempt to address the shortcomings in therapy associated with the use of conventional dosage forms. The shortcomings include the unpalatable taste of API in solution, instability in the presence of light when in solution and psychiatric side effects of the API. In particular, sustained release approaches may reduce or limit the incidence of adverse psychiatric effects of EFV and alleviate Acquired Immune Deficiency Syndrome (AIDS)-related complications such as AIDS Dementia Complex (ADC) in patients, ultimately improving their quality of life. Prior to initiating pre-formulation, formulation development and optimization studies of EFV-loaded SLN and/or NLC, Response Surface Methodology (RSM) in conjunction with central composite design (CCD), was used to develop and validate suitable methods for the quantitative determination of EFV in pharmaceutical formulations and for monitoring EFV release from SLN and/or NLC in vitro. Simple, accurate, precise, sensitive and stabilityindicating reversed phase-high performance liquid chromatography (RP-HPLC) methods with UV and electrochemical (EC) detection were developed, validated and optimized for in vitro analysis of EFV in formulations. On the basis of risk-to-benefit ratio the RP-HPLC method with UV detection was selected as the most suitable for the quantitative determination of EFV in pharmaceutical formulations, and was applied to in vitro release studies of EFV from SLN and/or NLC. Pre-formulation studies were undertaken to investigate the thermal stability of EFV so as to facilitate the selection of lipid excipients for the manufacture of nanocarriers, and to establish their compatibility with EFV. It was found that EFV was thermostable up to a temperature of approximately 200°C, indicating that HHPH could be used for the manufacture of EFV-loaded SLN and/or NLC. Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate and Transcutol® HP showing the best solubilizing potential for EFV. Glyceryl monostearate exists in a stable β-modification prior to exposure to heat, but exists in the α-polymorphic modification following exposure to heat. It was established that the addition of Transcutol® HP to glyceryl monostearate revealed the co-existence of the α- and β’-polymorphic modifications, thereby revealing the existence of the modifications in NLC produced from the optimum lipid combination. Furthermore, an investigation of binary mixtures of EFV/glyceryl monostearate and glyceryl monostearate/Transcutol® HP, in addition to eutectic mixtures of EFV, glyceryl monostearate and Transcutol® HP, revealed no interaction between EFV and the lipids selected for the production of the nanocarriers. Due to the significantly higher solubility of EFV in Transcutol® HP than in to glyceryl monostearate, NLC are most likely to have a higher LC and EE than SLN. In addition, the existence of both the α- and β’-polymorphic modifications in the binary mixture of the lipid implies that EFV expulsion on prolonged storage is unlikely to occur from NLC when compared to SLN. Consequently formulation development and optimization studies of SLN and NLC were performed to investigate the potential to deliver EFV from a novel technology with an appropriate LC and EE for EFV. Tween®80 was selected for use in these formulations as the use of this surfactant facilitates the targeting of nanocarriers to the CNS. RSM in conjunction with a Box-Behnken Design (BBD) was used to establish the effects of process variables, such as number of homogenization cycles and pressure, in addition to formulation variables such as amount of EFV and Tween®80 on the particle size (PS), polydispersity index (PDI), zeta potential (ZP), visual assessment (VA) and release rate (RR) of EFV after 24 hours. In addition the LC and EE, degree of crystallinity and lipid modification, shape and surface morphology of the optimized batches were investigated to ensure that EFV-loaded SLN and NLC of desirable quality were produced. On the day of manufacture the mean PS and PDI of EFV-loaded SLN was 59.00 ± 23.16 nm and 0.382 ± 0.054 respectively. The mean PS and PDI of EFV-loaded NLC was 34.73 ± 0.7709 nm and 0.394 ± 0.027 respectively. The formulations were in the nanometer range and exhibited a narrow particle size distribution, as indicated by the PDI values. The ZP values for optimized SLN and NLC generated on the day of manufacture using HPLC grade water as the dispersion medium were -32.5 ± 4.99 mV and -22.4 ± 3.72 mV respectively. In addition the optimized batches of SLN and NLC revealed a decrease in crystallinity in comparison to bulk lipid material. DSC, WAXS and FT-IR revealed that EFV was molecularly dispersed in the nanocarriers. In addition EFV-loaded SLN existed in a single α-polymorphic form, whereas EFV-loaded NLC exhibited the co-existence of α- and β’-polymorphic forms. Generally SLN and NLC were spherically shaped when viewed under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the day of manufacture the EE and LC of EFVloaded SLN was found to be 96.77 ± 0.453 % and 9.68 ± 1.772 % respectively. The EE and LC of EFV-loaded NLC was 99.93 ± 0.413 and 9.995 ± 0.672 respectively. The release profiles for the optimized formulations of SLN and NLC exhibited an initial burst release over the first 0-3 hours of testing, after which the release was sustained for up to 24 hours. The cumulative % EFV released over 24 hours was higher from SLN (91.5±3.423 %) than that observed for NLC (73.6±4.34 %). Stability studies performed for 8 weeks on the optimized batches of the SLN and the NLC were also conducted so as to ensure product quality. The formulations were assessed in terms of parameters considered benchmarks of stability, and included ZP, PS, PDI, LC and EE. Generally these parameters remained unchanged following storage for 8 weeks at 25°C/60% RH but showed considerable changes following storage for 8 weeks at 40°C/75% RH. These studies reveal that SLN and NLC when stored at 25°C/60% RH have the potential to be used as colloidal delivery systems for EFV that have the potential to protect EFV from photodegradation and sustain release into brain tissue. The latter will ultimately reduce or limit the incidence of adverse psychiatric effects and potentially alleviate AIDS-related complications such as ADC in patients with HIV/AIDS, ultimately improving their quality of life. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2014
- Full Text:
Foundation Phase teachers’ responses to curriculum change in South Africa over the past two decades: a case study of two schools
- Authors: Nakaonga, Ruth
- Date: 2014
- Subjects: Curriculum change -- South Africa , Educational change -- South Africa , Education, Primary -- South Africa , Teachers -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2002 , http://hdl.handle.net/10962/d1015648
- Description: South Africa has experienced three significant curriculum reforms since 1994. The first of these replaced the ‘apartheid’ curriculum with C2005 based largely on Outcomes Based Education. In the second stage C2005 gave way to the National Curriculum Statements, a simplified version of C2005. Finally, the NCS was replaced with CAPS. This research study investigates the perceptions, attitudes and experiences of teachers implementing these curriculum changes. It focuses in particular on Foundation Phase in 2012, the year in which CAPS was implemented in that phase. It took the form of an interpretive case study, using qualitative data generating and analysis techniques. Principals and selected teachers of two primary schools in Grahamstown – an ex-Model C school and a performing ‘township’ school - were the respondents of the study. Data were generated chiefly through questionnaires and semi-structured interviews, supplemented by document analysis and observation. The findings revealed that the teachers in this study are frustrated and angry about the frequency of curriculum change in South Africa. Respondents are particularly critical of OBE and the NCS. While they welcome the need for a departure from ‘apartheid’ curricula, they feel the pedagogical underpinning of the NCS – with its emphasis on learner-centredness – disempowered them as teachers. Hence, they welcomed CAPS which seems to return to content – rather than skills and attitudes – and re-instates the teacher as the chief giver of knowledge and manager of learning.
- Full Text:
- Authors: Nakaonga, Ruth
- Date: 2014
- Subjects: Curriculum change -- South Africa , Educational change -- South Africa , Education, Primary -- South Africa , Teachers -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2002 , http://hdl.handle.net/10962/d1015648
- Description: South Africa has experienced three significant curriculum reforms since 1994. The first of these replaced the ‘apartheid’ curriculum with C2005 based largely on Outcomes Based Education. In the second stage C2005 gave way to the National Curriculum Statements, a simplified version of C2005. Finally, the NCS was replaced with CAPS. This research study investigates the perceptions, attitudes and experiences of teachers implementing these curriculum changes. It focuses in particular on Foundation Phase in 2012, the year in which CAPS was implemented in that phase. It took the form of an interpretive case study, using qualitative data generating and analysis techniques. Principals and selected teachers of two primary schools in Grahamstown – an ex-Model C school and a performing ‘township’ school - were the respondents of the study. Data were generated chiefly through questionnaires and semi-structured interviews, supplemented by document analysis and observation. The findings revealed that the teachers in this study are frustrated and angry about the frequency of curriculum change in South Africa. Respondents are particularly critical of OBE and the NCS. While they welcome the need for a departure from ‘apartheid’ curricula, they feel the pedagogical underpinning of the NCS – with its emphasis on learner-centredness – disempowered them as teachers. Hence, they welcomed CAPS which seems to return to content – rather than skills and attitudes – and re-instates the teacher as the chief giver of knowledge and manager of learning.
- Full Text:
General structural and functional features of molecular chaperones:
- Edkins, Adrienne L, Boshoff, Aileen
- Authors: Edkins, Adrienne L , Boshoff, Aileen
- Date: 2014
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/164808 , vital:41174 , ISBN 978-94-007-7437-7 , DOI: 10.1007/978-94-007-7438-4_2
- Description: Molecular chaperones are a group of structurally diverse and highly conserved ubiquitous proteins. They play crucial roles in facilitating the correct folding of proteins in vivo by preventing protein aggregation or facilitating the appropriate folding and assembly of proteins. Heat shock proteins form the major class of molecular chaperones that are responsible for protein folding events in the cell. This is achieved by ATP-dependent (folding machines) or ATP-independent mechanisms (holders). Heat shock proteins are induced by a variety of stresses, besides heat shock. The large and varied heat shock protein class is categorised into several subfamilies based on their sizes in kDa namely, small Hsps (HSPB), Hsp40 (DNAJ), Hsp60 (HSPD/E; Chaperonins), Hsp70 (HSPA), Hsp90 (HSPC), and Hsp100.
- Full Text:
- Authors: Edkins, Adrienne L , Boshoff, Aileen
- Date: 2014
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/164808 , vital:41174 , ISBN 978-94-007-7437-7 , DOI: 10.1007/978-94-007-7438-4_2
- Description: Molecular chaperones are a group of structurally diverse and highly conserved ubiquitous proteins. They play crucial roles in facilitating the correct folding of proteins in vivo by preventing protein aggregation or facilitating the appropriate folding and assembly of proteins. Heat shock proteins form the major class of molecular chaperones that are responsible for protein folding events in the cell. This is achieved by ATP-dependent (folding machines) or ATP-independent mechanisms (holders). Heat shock proteins are induced by a variety of stresses, besides heat shock. The large and varied heat shock protein class is categorised into several subfamilies based on their sizes in kDa namely, small Hsps (HSPB), Hsp40 (DNAJ), Hsp60 (HSPD/E; Chaperonins), Hsp70 (HSPA), Hsp90 (HSPC), and Hsp100.
- Full Text:
Genesis of BIF-hosted hematite iron ore deposits in the central part of the Maremane anticline, Northern Cape Province, South Africa
- Authors: Land, Jarred
- Date: 2014
- Subjects: Hematite -- South Africa -- Northern Cape , Anticlines -- South Africa -- Northern Cape , Geology, Stratigraphic -- Proterozoic , Hydrothermal deposits -- Northern Cape , Rare earth metals -- Northern Cape , Iron ores -- Geology -- Northern Cape , Transvaal Supergroup (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5095 , http://hdl.handle.net/10962/d1020905
- Description: The Paleoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to high-grade BIF-hosted hematite iron-ore deposits and is the country’s most important source of iron to date. Previous work has failed to provide a robust and all-inclusive genetic model for such deposits in the Transvaal Supergroup; in particular, the role of hydrothermal processes in ore-genesis has not been adequately clarified. Recent studies by the author have produced evidence for hydrothermal alteration in shales (Olifantshoek Supergroup) stratigraphically overlying the iron-ore intervals; this has highlighted the need to reassess current ore-forming models which place residual supergene processes at the core of oregenesis. This thesis focuses on providing new insights into the processes responsible for the genesis of hematite iron ores in the Maremane anticline through the use of newly available exploration drill-core material from the centre of the anticline. The study involved standard mineralogical investigations using transmitted/reflected light microscopy as well as instrumental techniques (XRD, EPMA); and the employment of traditional whole-rock geochemical analysis on samples collected from two boreholes drilled in the centre of the Maremane anticline, Northern Cape Province. Rare earth element analysis (via ICP-MS) and oxygen isotope data from hematite separates complement the whole-rock data. Iron-ore mineralisation examined in this thesis is typified by the dominance of Fe-oxide (as hematite), which reaches whole-rock abundances of up to 98 wt. % Fe₂O₃. Textural and whole-rock geochemical variations in the ores likely reflect a variable protolith, from BIF to Fe-bearing shale. A standard supergene model invoking immobility and residual enrichment of iron is called into question on the basis of the relative degrees of enrichment recorded in the ores with respect to other, traditionally immobile elements during chemical weathering, such as Al₂O₃ and TiO₂. Furthermore, the apparently conservative behaviour of REE in the Fe ore (i.e. low-grade and high-grade iron ore) further emphasises the variable protolith theory. Hydrothermally-induced ferruginisation is suggested to post-date the deposition of the post-Transvaal Olifantshoek shales, and is likely to be linked to a sub-surface transgressive hydrothermal event which indiscriminately transforms both shale and BIF into Fe-ore. A revised, hydrothermal model for the formation of BIF-hosted high-grade hematite iron ore deposits in the central part of the Maremane anticline is proposed, and some ideas of the author for further follow-up research are presented.
- Full Text:
- Authors: Land, Jarred
- Date: 2014
- Subjects: Hematite -- South Africa -- Northern Cape , Anticlines -- South Africa -- Northern Cape , Geology, Stratigraphic -- Proterozoic , Hydrothermal deposits -- Northern Cape , Rare earth metals -- Northern Cape , Iron ores -- Geology -- Northern Cape , Transvaal Supergroup (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5095 , http://hdl.handle.net/10962/d1020905
- Description: The Paleoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to high-grade BIF-hosted hematite iron-ore deposits and is the country’s most important source of iron to date. Previous work has failed to provide a robust and all-inclusive genetic model for such deposits in the Transvaal Supergroup; in particular, the role of hydrothermal processes in ore-genesis has not been adequately clarified. Recent studies by the author have produced evidence for hydrothermal alteration in shales (Olifantshoek Supergroup) stratigraphically overlying the iron-ore intervals; this has highlighted the need to reassess current ore-forming models which place residual supergene processes at the core of oregenesis. This thesis focuses on providing new insights into the processes responsible for the genesis of hematite iron ores in the Maremane anticline through the use of newly available exploration drill-core material from the centre of the anticline. The study involved standard mineralogical investigations using transmitted/reflected light microscopy as well as instrumental techniques (XRD, EPMA); and the employment of traditional whole-rock geochemical analysis on samples collected from two boreholes drilled in the centre of the Maremane anticline, Northern Cape Province. Rare earth element analysis (via ICP-MS) and oxygen isotope data from hematite separates complement the whole-rock data. Iron-ore mineralisation examined in this thesis is typified by the dominance of Fe-oxide (as hematite), which reaches whole-rock abundances of up to 98 wt. % Fe₂O₃. Textural and whole-rock geochemical variations in the ores likely reflect a variable protolith, from BIF to Fe-bearing shale. A standard supergene model invoking immobility and residual enrichment of iron is called into question on the basis of the relative degrees of enrichment recorded in the ores with respect to other, traditionally immobile elements during chemical weathering, such as Al₂O₃ and TiO₂. Furthermore, the apparently conservative behaviour of REE in the Fe ore (i.e. low-grade and high-grade iron ore) further emphasises the variable protolith theory. Hydrothermally-induced ferruginisation is suggested to post-date the deposition of the post-Transvaal Olifantshoek shales, and is likely to be linked to a sub-surface transgressive hydrothermal event which indiscriminately transforms both shale and BIF into Fe-ore. A revised, hydrothermal model for the formation of BIF-hosted high-grade hematite iron ore deposits in the central part of the Maremane anticline is proposed, and some ideas of the author for further follow-up research are presented.
- Full Text:
Genesis of karst-hosted manganese ores of the Postmasburg Manganese Field, South Africa with emphasis on evidence for hydrothermal processes
- Authors: Fairey, Brenton John
- Date: 2014
- Subjects: Karst -- South Africa -- Postmasburg , Manganese ores -- South Africa -- Postmasburg , Hydrothermal alteration -- South Africa -- Postmasburg , Manganese mines and mining -- South Africa -- Northern Cape , Petrology , Mineralogical chemistry , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5094 , http://hdl.handle.net/10962/d1020904
- Description: The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, once represented one of the largest sources of manganese ore worldwide. However, the discovery of the giant manganese deposits of the Kalahari Manganese Field (KMF) led to the gradual decline in manganese mining activity in the PMF. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes in ore formation and metasomatic alteration is not addressed. The identification of an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in the PMF ores studied in this thesis, is indicative of the influence of hydrothermal activity. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for the majority of samples analysed through bulk-rock techniques. The discovery of a Ba-Mn arsenate/vanadate similar to gamagarite may also indicate that the hydrothermal fluid affecting the ores was not only alkali-rich but also probably contained some As and V. The fluid was likely to be oxidized and alkaline in nature and is thought to have been a mature basinal brine. Various replacement textures, particularly of Na- and Krich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as oreminerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and the deviation of their character from the pigeon-hole-type classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. The discovery of hydrothermallydeposited alkali-rich assemblages in the PMF and KMF provides grounding for further investigation into a possible regional-scale hydrothermal event at least re-constituting the ores. Some shortcomings in previous works include disregard for the highly variable nature of the PMF deposits, the effects of hydrothermal activity of the ores and the existence of stratigraphic discrepancies. This study provides a single, broad model for the development of all manganese deposits of the PMF. The source of metals is attributed to all formations that stratigraphically overly the Reivilo Formation of the Campbellrand Subgroup (including the Reivilo Formation itself). The main process by which metals are accumulated is attributed to karstification of the dolomites. The interaction of oxidized, alkaline brines with the ores is considered and the overlying Asbestos Hills Subgroup BIF is suggested as a potential source of alkali metals.
- Full Text:
- Authors: Fairey, Brenton John
- Date: 2014
- Subjects: Karst -- South Africa -- Postmasburg , Manganese ores -- South Africa -- Postmasburg , Hydrothermal alteration -- South Africa -- Postmasburg , Manganese mines and mining -- South Africa -- Northern Cape , Petrology , Mineralogical chemistry , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5094 , http://hdl.handle.net/10962/d1020904
- Description: The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, once represented one of the largest sources of manganese ore worldwide. However, the discovery of the giant manganese deposits of the Kalahari Manganese Field (KMF) led to the gradual decline in manganese mining activity in the PMF. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes in ore formation and metasomatic alteration is not addressed. The identification of an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in the PMF ores studied in this thesis, is indicative of the influence of hydrothermal activity. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for the majority of samples analysed through bulk-rock techniques. The discovery of a Ba-Mn arsenate/vanadate similar to gamagarite may also indicate that the hydrothermal fluid affecting the ores was not only alkali-rich but also probably contained some As and V. The fluid was likely to be oxidized and alkaline in nature and is thought to have been a mature basinal brine. Various replacement textures, particularly of Na- and Krich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as oreminerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and the deviation of their character from the pigeon-hole-type classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. The discovery of hydrothermallydeposited alkali-rich assemblages in the PMF and KMF provides grounding for further investigation into a possible regional-scale hydrothermal event at least re-constituting the ores. Some shortcomings in previous works include disregard for the highly variable nature of the PMF deposits, the effects of hydrothermal activity of the ores and the existence of stratigraphic discrepancies. This study provides a single, broad model for the development of all manganese deposits of the PMF. The source of metals is attributed to all formations that stratigraphically overly the Reivilo Formation of the Campbellrand Subgroup (including the Reivilo Formation itself). The main process by which metals are accumulated is attributed to karstification of the dolomites. The interaction of oxidized, alkaline brines with the ores is considered and the overlying Asbestos Hills Subgroup BIF is suggested as a potential source of alkali metals.
- Full Text:
Genetic and biological characterisation of a novel South African Plutella xylostella granulovirus (PlxyGV) isolate
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
Genetic and morphometric variation of Octopus vulgaris in the Benguela Current region
- Authors: De Beer, Chénelle Lesley
- Date: 2014
- Subjects: Common octopus -- Africa, Southern , Common octopus -- Genetics , Common octopus -- Morphology , Common octopus -- Geographical distribution , Variation (Biology) , Benguela Current
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5362 , http://hdl.handle.net/10962/d1012971
- Description: The Benguela Current is a cold eastern boundary current located on the south-western coast of the African continent. The establishment of its present day features approximately two million years ago has triggered allopatric events which have driven genetic and/or phenotypic differentiation in many of the warm-temperate organisms that previously had continuous distributions along the south and west coast of southern Africa. However, since many of these species have responded differently, despite similar isolation times, research in this region provides a unique opportunity to increase our understanding of evolutionary processes. The common octopus (Octopus vulgaris, Cuvier 1797) is a coastal, sedentary species, inhabiting coral reefs or rocky environments at depths of up to a 100m. It is considered to be one of the most extensively studied cephalopod species due to its worldwide distribution. However, very little research has been conducted on O. vulgaris in southern Africa. In order to gain a holistic understanding of the effects of the Benguela Current on population connectivity, genetic and phenotypic diversity, and evolutionary history of O. vulgaris, a comparative genetic and morphological study was conducted across the Benguela region. A total of 168 specimens of O. vulgaris were collected from four different regions across the Benguela system. A small tissue sample was preserved in ethanol for molecular analysis, and the specimen was frozen whole for morphometric analysis in the laboratory. Octopus vulgaris genetic population structure and evolutionary history was investigated using a 580bp fragment of the mitochondrial cytochrome b (cytb) gene for 76 individuals located within the Benguela region, yielding 10 different haplotypes. AMOVA and pairwise FST analyses revealed significant genetic differentiation suggesting a northern-southern Benguela divergence. Estimates of time since most recent common ancestor, based on biogeographical calibrators and coalescent analyses, indicated that isolation between the Angolan and South African population occurred between ~231 Ka and 1 Ma. Mismatch distribution analyses revealed a past population expansion within the South African O. vulgaris roughly 129.31 Ka, whilst Bayesian skyline plots were indicative of gradual demographic growth within the Angolan population in the last ~100 Ka. Observed O. vulgaris population structure and demographic history was likely the result of historical climate-induced change within the system. Reconstruction of phylogenetic relationships within the Octopus genus, using cytb and COI suggest that O. vulgaris is not a monophyletic group and a major systematic revision is required. Furthermore, unidentified individuals from South Africa were found to group with species from Indo-West Pacific Oceans and were therefore considered to have been translocated through ballast water from Asia. While the molecular analysis indicated a significant northern-southern Benguela structure results from the principle component analysis (PCA) and discriminate function analysis (DFA) were unable to distinguish between O. vulgaris from different sampling localities throughout the Benguela Current region based on soft-parts, hard-parts and meristic characters. The lack of phenotypic variation, despite significant genetic divergence, highlights the importance of multi-method approaches in gaining a holistic understanding of the taxonomy and biogeography of species.
- Full Text:
- Authors: De Beer, Chénelle Lesley
- Date: 2014
- Subjects: Common octopus -- Africa, Southern , Common octopus -- Genetics , Common octopus -- Morphology , Common octopus -- Geographical distribution , Variation (Biology) , Benguela Current
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5362 , http://hdl.handle.net/10962/d1012971
- Description: The Benguela Current is a cold eastern boundary current located on the south-western coast of the African continent. The establishment of its present day features approximately two million years ago has triggered allopatric events which have driven genetic and/or phenotypic differentiation in many of the warm-temperate organisms that previously had continuous distributions along the south and west coast of southern Africa. However, since many of these species have responded differently, despite similar isolation times, research in this region provides a unique opportunity to increase our understanding of evolutionary processes. The common octopus (Octopus vulgaris, Cuvier 1797) is a coastal, sedentary species, inhabiting coral reefs or rocky environments at depths of up to a 100m. It is considered to be one of the most extensively studied cephalopod species due to its worldwide distribution. However, very little research has been conducted on O. vulgaris in southern Africa. In order to gain a holistic understanding of the effects of the Benguela Current on population connectivity, genetic and phenotypic diversity, and evolutionary history of O. vulgaris, a comparative genetic and morphological study was conducted across the Benguela region. A total of 168 specimens of O. vulgaris were collected from four different regions across the Benguela system. A small tissue sample was preserved in ethanol for molecular analysis, and the specimen was frozen whole for morphometric analysis in the laboratory. Octopus vulgaris genetic population structure and evolutionary history was investigated using a 580bp fragment of the mitochondrial cytochrome b (cytb) gene for 76 individuals located within the Benguela region, yielding 10 different haplotypes. AMOVA and pairwise FST analyses revealed significant genetic differentiation suggesting a northern-southern Benguela divergence. Estimates of time since most recent common ancestor, based on biogeographical calibrators and coalescent analyses, indicated that isolation between the Angolan and South African population occurred between ~231 Ka and 1 Ma. Mismatch distribution analyses revealed a past population expansion within the South African O. vulgaris roughly 129.31 Ka, whilst Bayesian skyline plots were indicative of gradual demographic growth within the Angolan population in the last ~100 Ka. Observed O. vulgaris population structure and demographic history was likely the result of historical climate-induced change within the system. Reconstruction of phylogenetic relationships within the Octopus genus, using cytb and COI suggest that O. vulgaris is not a monophyletic group and a major systematic revision is required. Furthermore, unidentified individuals from South Africa were found to group with species from Indo-West Pacific Oceans and were therefore considered to have been translocated through ballast water from Asia. While the molecular analysis indicated a significant northern-southern Benguela structure results from the principle component analysis (PCA) and discriminate function analysis (DFA) were unable to distinguish between O. vulgaris from different sampling localities throughout the Benguela Current region based on soft-parts, hard-parts and meristic characters. The lack of phenotypic variation, despite significant genetic divergence, highlights the importance of multi-method approaches in gaining a holistic understanding of the taxonomy and biogeography of species.
- Full Text:
Geographical variation in effects of nutrient levels and grazing intensity on community structure between upwelling and non-upwelling regions of South Africa
- Authors: Steele, Nikita
- Date: 2014
- Subjects: Upwelling (Oceanography) , Upwelling (Oceanography) -- Indian Ocean , Algae -- Indian Ocean , Algae -- Effect of grazing on -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5873 , http://hdl.handle.net/10962/d1013013
- Description: The aim of this thesis was to assess the influence of upwelling on alga-grazer interactions in rocky shore communities along the south coast of South Africa using grazer exclusion treatments with controls and procedural controls set out in a block design and monitored for algal cover roughly monthly for one year. In the first experiment grazers were excluded from treatment plots at two upwelling and two non-upwelling sites and the rates of algal biomass accumulation were then compared. The upwelling sites showed significantly faster algal colonisation rates, with Ulva rigida being the first species to colonise the rocks. Final algal cover and biomass did not differ significantly between upwelling and non-upwelling sites in control plots open to grazers, but were significantly higher in grazer exclusion plots at upwelling sites indicating stronger grazing effects. This was confirmed by estimating the intensity of grazing using the log-response ratio (LRR), which was calculated from treatment and control plots. Upwelling sites had significantly lower LLR values indicating stronger grazing effects, than at non-upwelling sites, despite no difference in grazer abundances. The second experiment examined the effects of nutrient addition on algal growth and community composition by comparing high nutrient enrichment plots with low enrichment plots at one upwelling and one non-upwelling site. ANOVA indicated faster growth rates and significantly higher final algal biomass in high enrichment plots compared to low enrichment and control plots at both upwelling and non-upwelling sites. A two-way ANOVA indicated significantly higher algal cover in high enrichment plots compared to the data from the grazer exclusion plots in experiment 1 at both sites, suggesting that nutrient addition plays a major role in algal growth and community composition. The findings of these studies have shown significant differences between treatments, sites and seasons, with significant differences not only occurring in algal cover but also accumulation of algal biomass and recruitment patterns between treatments. The small scale local processes acting within a few centimetres (plots) or tens of meters (among blocks) can also be reflected over larger scales such as sites (upwelling/non-upwelling shores). Further, these studies have demonstrated that various factors such as the effects from increased nutrients at upwelling cells and the change in grazing effects due to enhanced nutrients can determine the abundance and diversity of the community structure, including an increase in the abundance of the fast growing algae Ulva rigida, and a slow recovery of the brown and red algae.
- Full Text:
- Authors: Steele, Nikita
- Date: 2014
- Subjects: Upwelling (Oceanography) , Upwelling (Oceanography) -- Indian Ocean , Algae -- Indian Ocean , Algae -- Effect of grazing on -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5873 , http://hdl.handle.net/10962/d1013013
- Description: The aim of this thesis was to assess the influence of upwelling on alga-grazer interactions in rocky shore communities along the south coast of South Africa using grazer exclusion treatments with controls and procedural controls set out in a block design and monitored for algal cover roughly monthly for one year. In the first experiment grazers were excluded from treatment plots at two upwelling and two non-upwelling sites and the rates of algal biomass accumulation were then compared. The upwelling sites showed significantly faster algal colonisation rates, with Ulva rigida being the first species to colonise the rocks. Final algal cover and biomass did not differ significantly between upwelling and non-upwelling sites in control plots open to grazers, but were significantly higher in grazer exclusion plots at upwelling sites indicating stronger grazing effects. This was confirmed by estimating the intensity of grazing using the log-response ratio (LRR), which was calculated from treatment and control plots. Upwelling sites had significantly lower LLR values indicating stronger grazing effects, than at non-upwelling sites, despite no difference in grazer abundances. The second experiment examined the effects of nutrient addition on algal growth and community composition by comparing high nutrient enrichment plots with low enrichment plots at one upwelling and one non-upwelling site. ANOVA indicated faster growth rates and significantly higher final algal biomass in high enrichment plots compared to low enrichment and control plots at both upwelling and non-upwelling sites. A two-way ANOVA indicated significantly higher algal cover in high enrichment plots compared to the data from the grazer exclusion plots in experiment 1 at both sites, suggesting that nutrient addition plays a major role in algal growth and community composition. The findings of these studies have shown significant differences between treatments, sites and seasons, with significant differences not only occurring in algal cover but also accumulation of algal biomass and recruitment patterns between treatments. The small scale local processes acting within a few centimetres (plots) or tens of meters (among blocks) can also be reflected over larger scales such as sites (upwelling/non-upwelling shores). Further, these studies have demonstrated that various factors such as the effects from increased nutrients at upwelling cells and the change in grazing effects due to enhanced nutrients can determine the abundance and diversity of the community structure, including an increase in the abundance of the fast growing algae Ulva rigida, and a slow recovery of the brown and red algae.
- Full Text:
Geomorphic origin and dynamics of deep, peat-filled, valley bottom wetlands dominated by palmiet (Prionium serratum) : a case study based on the Goukou Wetland, Western Cape
- Authors: Job, Nancy Merle
- Date: 2014
- Subjects: Wetlands -- South Africa -- Western Cape , Peatlands -- South Africa -- Western Cape , Peatland conservation -- South Africa -- Western Cape , Peatland management -- South Africa , Aquatic plants -- South Africa -- Western Cape , Geomorphology -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4782 , http://hdl.handle.net/10962/d1013122
- Description: The Goukou Wetland is a 700 ha unchannelled valley bottom wetland near the town of Riversdale in the Western Cape of South Africa. The wetland is approximately 16 km long and between 200 and 800 m wide, with peat deposits up to 8 m deep that get progressively shallower downstream. The Goukou Wetland is one of the last remaining intact peatlands of significant size in the Western Cape. However, there is increasing human pressure on these peat wetlands, where the dominant plant is palmiet (Prionium serratum), which is endemic to the Western and Eastern Cape Provinces of South Africa. Palmiet is viewed as a problem plant by farmers as it is believed to block waterways and promote inundation of arable land and infrastructure. Many landowners therefore actively remove palmiet from peatlands, threatening the integrity of these wetlands. Although the hydrogeomorphic origin of large, non-peat floodplain and valley bottom wetlands has been investigated in South Africa, unchannelled valley-bottom wetlands with deep peat accumulations are rare features and have not been well studied. The hydrogeomorphic factors leading to peat accumulation have been documented elsewhere in Southern Africa, where aggradation due to sedimentation along trunk streams may block a tributary stream, elevating the local base level of the tributary, creating the accommodation space for organic sedimentation. Alternatively, sedimentation along a trunk stream at the toe of a tributary stream may similarly block a trunk stream, promoting organic sedimentation along the trunk stream upstream of the tributary. This pattern of peat accumulation is associated with declining peat thickness upstream of the blocked valley. In the case of the Goukou Wetland, however, peat depth and organic content was found to increase consistently upstream from the toe to the head of the wetland. The Goukou Wetland was graded along its length, with gradient increasing consistently upstream in response to longitudinal variation in discharge. There was no clear relationship between peat formation and tributary streams blocking the wetland. Instead, the distribution of peat and the extent of the wetland appeared to be controlled by the plant palmiet, whose clonal nature and robust root, rhizome and stem system allowed it to grow from channel banks and islands into fast-flowing river channels, slowing river flows and ultimately blocking the channel. The promotion of diffuse flows within the dense, monospecific stands of palmiet creates conditions conducive to water retention and peat accumulation. By growing across the full width of the valley floor, the plant is able to constrict the stream, trapping sediment and slowing flows such that the fluvial environment is changed from a fast flowing stream to one with slow, diffuse flow. These processes appear to lead to the formation of organic sediment, accumulating to form a deep peat basin. The sustained input of water from the folded and fractured quartzite lithologies of the Cape Supergroup that make up the Langeberg Mountains, which provide the bulk of the water supply to the wetland, is also important in promoting permanent flooding in the wetland. A feature that characterized the wetland was the fact that bedrock across the valley beneath the peat deposits exhibited a remarkably uniform elevation. This suggests that over long periods of time (tens to hundreds of thousands of years), bedrock has been laterally planed across the valley floor. It is proposed that valley widening associated with lateral planning of Uitenhage Formation rocks has taken place during periods of episodic very high flows. During these episodes, erosion cuts into the peat wetland and valley sides, cutting to bedrock and planing the valley floor to a uniform elevation for a given distance from the head of the wetland. Periods of episodic degradation are followed by periods of renewed peat accumulation associated with palmiet establishment, such that the wetland valley is shaped by repeated cycles of cutting and filling. Palmiet can be considered an “ecosystem engineer” that is integral to the formation of these deep peat basins. Removal of palmiet from these systems is likely to have negative consequences for the wetland and its functions in that water storage will be reduced, erosion will increase dramatically, and the water-purification function of the wetlands will be lost. Management of these wetlands, which are close to the geomorphic threshold slopes for their size, is therefore essential if they are to be preserved for the benefit of human well-being.
- Full Text:
- Authors: Job, Nancy Merle
- Date: 2014
- Subjects: Wetlands -- South Africa -- Western Cape , Peatlands -- South Africa -- Western Cape , Peatland conservation -- South Africa -- Western Cape , Peatland management -- South Africa , Aquatic plants -- South Africa -- Western Cape , Geomorphology -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4782 , http://hdl.handle.net/10962/d1013122
- Description: The Goukou Wetland is a 700 ha unchannelled valley bottom wetland near the town of Riversdale in the Western Cape of South Africa. The wetland is approximately 16 km long and between 200 and 800 m wide, with peat deposits up to 8 m deep that get progressively shallower downstream. The Goukou Wetland is one of the last remaining intact peatlands of significant size in the Western Cape. However, there is increasing human pressure on these peat wetlands, where the dominant plant is palmiet (Prionium serratum), which is endemic to the Western and Eastern Cape Provinces of South Africa. Palmiet is viewed as a problem plant by farmers as it is believed to block waterways and promote inundation of arable land and infrastructure. Many landowners therefore actively remove palmiet from peatlands, threatening the integrity of these wetlands. Although the hydrogeomorphic origin of large, non-peat floodplain and valley bottom wetlands has been investigated in South Africa, unchannelled valley-bottom wetlands with deep peat accumulations are rare features and have not been well studied. The hydrogeomorphic factors leading to peat accumulation have been documented elsewhere in Southern Africa, where aggradation due to sedimentation along trunk streams may block a tributary stream, elevating the local base level of the tributary, creating the accommodation space for organic sedimentation. Alternatively, sedimentation along a trunk stream at the toe of a tributary stream may similarly block a trunk stream, promoting organic sedimentation along the trunk stream upstream of the tributary. This pattern of peat accumulation is associated with declining peat thickness upstream of the blocked valley. In the case of the Goukou Wetland, however, peat depth and organic content was found to increase consistently upstream from the toe to the head of the wetland. The Goukou Wetland was graded along its length, with gradient increasing consistently upstream in response to longitudinal variation in discharge. There was no clear relationship between peat formation and tributary streams blocking the wetland. Instead, the distribution of peat and the extent of the wetland appeared to be controlled by the plant palmiet, whose clonal nature and robust root, rhizome and stem system allowed it to grow from channel banks and islands into fast-flowing river channels, slowing river flows and ultimately blocking the channel. The promotion of diffuse flows within the dense, monospecific stands of palmiet creates conditions conducive to water retention and peat accumulation. By growing across the full width of the valley floor, the plant is able to constrict the stream, trapping sediment and slowing flows such that the fluvial environment is changed from a fast flowing stream to one with slow, diffuse flow. These processes appear to lead to the formation of organic sediment, accumulating to form a deep peat basin. The sustained input of water from the folded and fractured quartzite lithologies of the Cape Supergroup that make up the Langeberg Mountains, which provide the bulk of the water supply to the wetland, is also important in promoting permanent flooding in the wetland. A feature that characterized the wetland was the fact that bedrock across the valley beneath the peat deposits exhibited a remarkably uniform elevation. This suggests that over long periods of time (tens to hundreds of thousands of years), bedrock has been laterally planed across the valley floor. It is proposed that valley widening associated with lateral planning of Uitenhage Formation rocks has taken place during periods of episodic very high flows. During these episodes, erosion cuts into the peat wetland and valley sides, cutting to bedrock and planing the valley floor to a uniform elevation for a given distance from the head of the wetland. Periods of episodic degradation are followed by periods of renewed peat accumulation associated with palmiet establishment, such that the wetland valley is shaped by repeated cycles of cutting and filling. Palmiet can be considered an “ecosystem engineer” that is integral to the formation of these deep peat basins. Removal of palmiet from these systems is likely to have negative consequences for the wetland and its functions in that water storage will be reduced, erosion will increase dramatically, and the water-purification function of the wetlands will be lost. Management of these wetlands, which are close to the geomorphic threshold slopes for their size, is therefore essential if they are to be preserved for the benefit of human well-being.
- Full Text:
Gold mineralisation at Masumbi Au-Cu Prospect, west Kenya : implication for gold exploration in the Archaean Ndori Greenstone Belt of Kenya
- Authors: Salimo, Luckmore
- Date: 2014
- Subjects: Gold mines and mining -- Kenya -- Nyanza Province , Copper -- Kenya -- Nyanza Province , Prospecting -- Kenya -- Nyanza Province , Chalcopyrite -- Kenya -- Nyanza Province , Metamorphism (Geology) , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5096 , http://hdl.handle.net/10962/d1020961
- Description: The Masumbi Au-Cu deposit in the Ndori Greenstone Belt of western Kenya is hosted in dacitic volcanics of the Nyanzian Group (2710 ± 340 Ma) and dioritic to granodioritic felsic intrusives (2504 ± 48 Ma). The deposit is characterised by gold and copper mineralisation that is associated with quartz-sulphide veins and veinlets. The copper mineralisation typically occurs as chalcopyrite. Gold is closely associated with pyrite in mineralogy and its pathfinder elements silver, bismuth, tellurium and selenium in geochemistry. The gold occurs in two forms that may indicate two generations of precipitation: the equant and the elongate forms. Based on Au/Ag ratios, the equant gold grains can be classified as native gold as their gold content is greater than 90 wt%. The elongate gold grains can be classified as electrums as their silver content is greater than 38 wt%. While there is a strong Au-Ag association within individual gold grains supporting an orogenic model for the gold mineralisation, mineralisation at the Masumbi Prospect appears atypical of Archaean orogenic gold deposits because of the abundance of copper (up to 0.43%). The enrichment of silver, copper, bismuth and tellurium in ore assemblages is common in porphyry, VMS and epithermal systems, but their presence at Masumbi does not preclude the formation as an orogenic deposit. Assay results from three Masumbi diamond drill-holes show an apparent correlation between gold and copper. However, petrography and electron probe microanalyses results from this study indicate that chalcopyrite is an earlier phase than pyrite as it occasionally occurs as inclusions in pyrite. This petrogenetic relationship between pyrite and chalcopyrite suggests that there is no temporal relationship between gold and copper mineralisation. Statistical analysis of the assays shows no linear correlation between gold and copper thereby supporting the above findings. The gold and copper mineralisation have been interpreted as forming as two separate events with copper forming first followed by gold. These events are both related to the intrusion of the felsic rocks that are associated with the Aruan metamorphic event that has been responsible for the bulk of the gold mineralisation on the Tanzanian Craton. The common alteration assemblage in the Masumbi rocks comprises chlorite and epidote. This alteration assemblage is typical of regional greenschist metamorphic facies grading into amphibolite metamorphic facies in the Nyanzian Group of Kenya. However, these alteration minerals could possibly be products of propylitic alteration in the rock groundmass. Other alteration mineral assemblages, possibly of hydrothermal origin, comprise muscovite, sericite, quartz, carbonate, associated with the sulphides pyrite and chalcopyrite. Although the occurrence of gold appears to be controlled by the presence of pyrite, it is also associated with silicification. Exploration methods have been proposed to target undiscovered gold deposits in the Ndori Greenstone Belt that are similar to the Masumbi deposit. These methods could probably be applied to vein-type gold deposits in other granite-greenstone terranes in the Lake Victoria Goldfields.
- Full Text:
- Authors: Salimo, Luckmore
- Date: 2014
- Subjects: Gold mines and mining -- Kenya -- Nyanza Province , Copper -- Kenya -- Nyanza Province , Prospecting -- Kenya -- Nyanza Province , Chalcopyrite -- Kenya -- Nyanza Province , Metamorphism (Geology) , Geochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5096 , http://hdl.handle.net/10962/d1020961
- Description: The Masumbi Au-Cu deposit in the Ndori Greenstone Belt of western Kenya is hosted in dacitic volcanics of the Nyanzian Group (2710 ± 340 Ma) and dioritic to granodioritic felsic intrusives (2504 ± 48 Ma). The deposit is characterised by gold and copper mineralisation that is associated with quartz-sulphide veins and veinlets. The copper mineralisation typically occurs as chalcopyrite. Gold is closely associated with pyrite in mineralogy and its pathfinder elements silver, bismuth, tellurium and selenium in geochemistry. The gold occurs in two forms that may indicate two generations of precipitation: the equant and the elongate forms. Based on Au/Ag ratios, the equant gold grains can be classified as native gold as their gold content is greater than 90 wt%. The elongate gold grains can be classified as electrums as their silver content is greater than 38 wt%. While there is a strong Au-Ag association within individual gold grains supporting an orogenic model for the gold mineralisation, mineralisation at the Masumbi Prospect appears atypical of Archaean orogenic gold deposits because of the abundance of copper (up to 0.43%). The enrichment of silver, copper, bismuth and tellurium in ore assemblages is common in porphyry, VMS and epithermal systems, but their presence at Masumbi does not preclude the formation as an orogenic deposit. Assay results from three Masumbi diamond drill-holes show an apparent correlation between gold and copper. However, petrography and electron probe microanalyses results from this study indicate that chalcopyrite is an earlier phase than pyrite as it occasionally occurs as inclusions in pyrite. This petrogenetic relationship between pyrite and chalcopyrite suggests that there is no temporal relationship between gold and copper mineralisation. Statistical analysis of the assays shows no linear correlation between gold and copper thereby supporting the above findings. The gold and copper mineralisation have been interpreted as forming as two separate events with copper forming first followed by gold. These events are both related to the intrusion of the felsic rocks that are associated with the Aruan metamorphic event that has been responsible for the bulk of the gold mineralisation on the Tanzanian Craton. The common alteration assemblage in the Masumbi rocks comprises chlorite and epidote. This alteration assemblage is typical of regional greenschist metamorphic facies grading into amphibolite metamorphic facies in the Nyanzian Group of Kenya. However, these alteration minerals could possibly be products of propylitic alteration in the rock groundmass. Other alteration mineral assemblages, possibly of hydrothermal origin, comprise muscovite, sericite, quartz, carbonate, associated with the sulphides pyrite and chalcopyrite. Although the occurrence of gold appears to be controlled by the presence of pyrite, it is also associated with silicification. Exploration methods have been proposed to target undiscovered gold deposits in the Ndori Greenstone Belt that are similar to the Masumbi deposit. These methods could probably be applied to vein-type gold deposits in other granite-greenstone terranes in the Lake Victoria Goldfields.
- Full Text:
Gold mineralization in a high grade metamorphic terrane in the Handeni District, Eastern Tanzania
- Bitesigirwe, Godfrey Stephen
- Authors: Bitesigirwe, Godfrey Stephen
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54756 , vital:26609
- Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
- Full Text:
- Authors: Bitesigirwe, Godfrey Stephen
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54756 , vital:26609
- Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
- Full Text:
Good-Gooder-Goodest
- Authors: Majola, Fundile Lawrence
- Date: 2014
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century , Short stories, South African -- 21st century , Short stories, Xhosa -- 21st century , Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Fiction , South African fiction -- Study and teaching (Higher)
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:5982 , http://hdl.handle.net/10962/d1015657
- Description: My stories are set in the townships, and move with the vigorous rhythms and jagged structures of township life. Some of them are written in English and others in isiXhosa. Some of the dialogue is township slang, a mixture of languages; and pure isiXhosa. The stories follow no particular pattern and are arranged according to any form of chronology, and different voices, at times as a man/boy and in others as a girl. The characters are not related each story perfectly stands for itself. Some of the stories hark back to the days of apartheid and are seen through the eyes of a child confused by the humiliations of his elders. , Amabali am asekelwe ezilokishini yaye ahambelana neemeko ezimaxongo zokuphila zasezilokishini apho yaye amanye asukela kwixesha lengcinezelo yesizwe esimnyama. Imiba echatshazelwa kula mabali iquka intlupheko, intiyo kwakunye nokuphilisana koluntu ezilokishini, phantsi kwezo meko. Amabali la ndizame ukuwenza alandele indlela yokubalisa yhenkwenkwana enguSkhumba, ethi ibone iqwalasele iimeko zokuphila zabantu bohlanga lwayo. Ingqokelela esisiqendu sokuqala yona ibhalwe ze yangeniswa ngesiNgesi. , This thesis is presented in two parts: English and isiXhosa.
- Full Text:
- Authors: Majola, Fundile Lawrence
- Date: 2014
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century , Short stories, South African -- 21st century , Short stories, Xhosa -- 21st century , Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Fiction , South African fiction -- Study and teaching (Higher)
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:5982 , http://hdl.handle.net/10962/d1015657
- Description: My stories are set in the townships, and move with the vigorous rhythms and jagged structures of township life. Some of them are written in English and others in isiXhosa. Some of the dialogue is township slang, a mixture of languages; and pure isiXhosa. The stories follow no particular pattern and are arranged according to any form of chronology, and different voices, at times as a man/boy and in others as a girl. The characters are not related each story perfectly stands for itself. Some of the stories hark back to the days of apartheid and are seen through the eyes of a child confused by the humiliations of his elders. , Amabali am asekelwe ezilokishini yaye ahambelana neemeko ezimaxongo zokuphila zasezilokishini apho yaye amanye asukela kwixesha lengcinezelo yesizwe esimnyama. Imiba echatshazelwa kula mabali iquka intlupheko, intiyo kwakunye nokuphilisana koluntu ezilokishini, phantsi kwezo meko. Amabali la ndizame ukuwenza alandele indlela yokubalisa yhenkwenkwana enguSkhumba, ethi ibone iqwalasele iimeko zokuphila zabantu bohlanga lwayo. Ingqokelela esisiqendu sokuqala yona ibhalwe ze yangeniswa ngesiNgesi. , This thesis is presented in two parts: English and isiXhosa.
- Full Text:
Grieving forests
- Authors: Bila, Freddy Vonani
- Date: 2014
- Subjects: Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Poetry , South African poetry (English) -- Study and teaching (Higher) , South African poetry (English) -- 21st century , English language -- Writing
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5997 , http://hdl.handle.net/10962/d1020880
- Description: This is a collection of village narrative poems mainly set in rural Limpopo that searches into the complexity of the past and how historical events impact on the present. Although the poems are imagined along the Marxist dialectic, they’re fresh imaginative creations featuring a strong element of surprise, spiritual mysticism, experimenting with form, delving into unknown poetic avenues, creating new music, exploring new sounds and taking risks. The long and intense poem, Ancestral wealth, which is a tribute to the poet’s father, reflects on death and its impact through the effective application of various stylistic elements and poetic devices, thus immortalising the life of a rural South African. Overall the poems, including retrospective and experimental ones, condemn the free market economic system and all that it seems to necessitate: the degradation of ecology, indifference to human suffering and the alienation of vulnerable social groups.
- Full Text:
- Authors: Bila, Freddy Vonani
- Date: 2014
- Subjects: Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Poetry , South African poetry (English) -- Study and teaching (Higher) , South African poetry (English) -- 21st century , English language -- Writing
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5997 , http://hdl.handle.net/10962/d1020880
- Description: This is a collection of village narrative poems mainly set in rural Limpopo that searches into the complexity of the past and how historical events impact on the present. Although the poems are imagined along the Marxist dialectic, they’re fresh imaginative creations featuring a strong element of surprise, spiritual mysticism, experimenting with form, delving into unknown poetic avenues, creating new music, exploring new sounds and taking risks. The long and intense poem, Ancestral wealth, which is a tribute to the poet’s father, reflects on death and its impact through the effective application of various stylistic elements and poetic devices, thus immortalising the life of a rural South African. Overall the poems, including retrospective and experimental ones, condemn the free market economic system and all that it seems to necessitate: the degradation of ecology, indifference to human suffering and the alienation of vulnerable social groups.
- Full Text:
Guardian of the furnace: mitochondria, TRAP1, ROS and stem cell maintenance
- Kadye, Rose, Kramer, Adam H, Joos-Vandewalle, Julia, Parsons, Michelle, Njengele, Zikhona, Hoppe, Heinrich, Prinsloo, Earl
- Authors: Kadye, Rose , Kramer, Adam H , Joos-Vandewalle, Julia , Parsons, Michelle , Njengele, Zikhona , Hoppe, Heinrich , Prinsloo, Earl
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431119 , vital:72745 , xlink:href="https://doi.org/10.1002/iub.1234"
- Description: Mitochondria are key to eukaryotic cell survival and their activity is linked to generation of reactive oxygen species (ROS) which in turn acts as both an intracellular signal and an effective executioner of cells with regards to cellular senescence. The mitochondrial molecular chaperone tumor necrosis factor receptor associated protein 1 (TRAP1) is often termed the cytoprotective chaperone for its role in cancer cell survival and protection from apoptosis. Here, we hypothesize that TRAP1 serves to modulate mitochondrial activity in stem cell maintenance, survival and differentiation.
- Full Text:
- Authors: Kadye, Rose , Kramer, Adam H , Joos-Vandewalle, Julia , Parsons, Michelle , Njengele, Zikhona , Hoppe, Heinrich , Prinsloo, Earl
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431119 , vital:72745 , xlink:href="https://doi.org/10.1002/iub.1234"
- Description: Mitochondria are key to eukaryotic cell survival and their activity is linked to generation of reactive oxygen species (ROS) which in turn acts as both an intracellular signal and an effective executioner of cells with regards to cellular senescence. The mitochondrial molecular chaperone tumor necrosis factor receptor associated protein 1 (TRAP1) is often termed the cytoprotective chaperone for its role in cancer cell survival and protection from apoptosis. Here, we hypothesize that TRAP1 serves to modulate mitochondrial activity in stem cell maintenance, survival and differentiation.
- Full Text:
Habitual transience : orientation and disorientation within non-places
- Authors: Heymans, Simone
- Date: 2014
- Subjects: Beeck, Hans Op de, 1969- , Space perception , Place (Philosophy) , Liminality , Art and society , Art, Modern -- 21st century , Art, Abstract -- 21st century
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2493 , http://hdl.handle.net/10962/d1013141
- Description: This mini-thesis is a supporting document to the exhibition titled via: a phenomenological site-specific series of intermedia interventions and installations at the 1820 Settlers National Monument in Grahamstown. This mini-thesis examines ways in which one negotiates the movement of the self and interactions with others within the non-place. Non-places are ‘habitually transient’ spaces for passage, communication and consumption, often viewed from highways, vehicles, hotels, petrol stations, airports and supermarkets. Characteristic of these generic and somewhat homogenous spaces is the paradox of material excess and concurrent psychological lack where a feeling of disorientation and disconnection is established due to the excesses of Supermodernity: excess of the individual, time and space. The non-place is a contested space as it does not hold enough significance to be regarded as a place and yet, despite its banality, is necessary – and in many ways a privilege – in everyday living. I explore the concept of non-places in relation to the intricate notions of space and place, and draw on empirical research as a means to interrogate how one perceives the phenomenological qualities of one’s surroundings. I discuss the implications of the multiplication of the non-place in relation to globalisation, time–space compression, site-specific art and absentmindedness, as theoretical themes which underpin the practical component of my research. In addition, I situate my artistic practice in relation to other contemporary artists dealing with the non-place as a theme, and critically engage with the multi-disciplinary and sensory installations and video pieces of Belgian artist Hans Op de Beeck.
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- Authors: Heymans, Simone
- Date: 2014
- Subjects: Beeck, Hans Op de, 1969- , Space perception , Place (Philosophy) , Liminality , Art and society , Art, Modern -- 21st century , Art, Abstract -- 21st century
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2493 , http://hdl.handle.net/10962/d1013141
- Description: This mini-thesis is a supporting document to the exhibition titled via: a phenomenological site-specific series of intermedia interventions and installations at the 1820 Settlers National Monument in Grahamstown. This mini-thesis examines ways in which one negotiates the movement of the self and interactions with others within the non-place. Non-places are ‘habitually transient’ spaces for passage, communication and consumption, often viewed from highways, vehicles, hotels, petrol stations, airports and supermarkets. Characteristic of these generic and somewhat homogenous spaces is the paradox of material excess and concurrent psychological lack where a feeling of disorientation and disconnection is established due to the excesses of Supermodernity: excess of the individual, time and space. The non-place is a contested space as it does not hold enough significance to be regarded as a place and yet, despite its banality, is necessary – and in many ways a privilege – in everyday living. I explore the concept of non-places in relation to the intricate notions of space and place, and draw on empirical research as a means to interrogate how one perceives the phenomenological qualities of one’s surroundings. I discuss the implications of the multiplication of the non-place in relation to globalisation, time–space compression, site-specific art and absentmindedness, as theoretical themes which underpin the practical component of my research. In addition, I situate my artistic practice in relation to other contemporary artists dealing with the non-place as a theme, and critically engage with the multi-disciplinary and sensory installations and video pieces of Belgian artist Hans Op de Beeck.
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Happiness, socioeconomic status, and family functioning in South African households
- Botha, Ferdie, Booysen, Frikkie
- Authors: Botha, Ferdie , Booysen, Frikkie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396075 , vital:69148 , xlink:href="https://doi.org/10.1007/s11205-013-0485-6"
- Description: This paper examines how SES relates to individual happiness, while also controlling for family functioning; the latter measured by the Family Attachment and Changeability Index 8 (FACI8). An individual-, household-, and subjective SES index are developed via multiple correspondence analyses (MCA). Using data from the 2012 South African Social Attitudes Survey (SASAS), the paper employs structural equation modelling (SEM) to explore the relationship between happiness, SES, and family functioning. Multiple-group SEM (MGSEM) is employed to examine the association between happiness and family functioning across quartiles of the three SES indices. The results reveal that higher SES is significantly related to greater happiness, with the role of household- and subjective SES being stronger than individual SES. Furthermore, improved levels of family changeability are positively associated with happiness, whereas there is no relationship between happiness and family attachment. Overall, levels of family changeability and individual happiness are likely to benefit from improvements in socioeconomic status.
- Full Text:
- Authors: Botha, Ferdie , Booysen, Frikkie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396075 , vital:69148 , xlink:href="https://doi.org/10.1007/s11205-013-0485-6"
- Description: This paper examines how SES relates to individual happiness, while also controlling for family functioning; the latter measured by the Family Attachment and Changeability Index 8 (FACI8). An individual-, household-, and subjective SES index are developed via multiple correspondence analyses (MCA). Using data from the 2012 South African Social Attitudes Survey (SASAS), the paper employs structural equation modelling (SEM) to explore the relationship between happiness, SES, and family functioning. Multiple-group SEM (MGSEM) is employed to examine the association between happiness and family functioning across quartiles of the three SES indices. The results reveal that higher SES is significantly related to greater happiness, with the role of household- and subjective SES being stronger than individual SES. Furthermore, improved levels of family changeability are positively associated with happiness, whereas there is no relationship between happiness and family attachment. Overall, levels of family changeability and individual happiness are likely to benefit from improvements in socioeconomic status.
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Higher education studies as a field of research
- Authors: McKenna, Sioux
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187405 , vital:44631 , xlink:href="https://hdl.handle.net/10520/EJC161436"
- Description: The field of Higher Education Studies is a rapidly growing one in South Africa and abroad but there has been little systematic review of the form this growth is taking. This article presents a case study of higher education research by considering a newly formed Higher Education Studies doctoral programme. The programme comprises 29 PhD scholars in 2014, all engaged in research on some aspect of higher education. The description of the PhD programme, the PhD scholars and what their research topics are, reveals a picture of the broad range of concerns within the field of Higher Education Studies and suggests that the field is a region, in Bernstein's terms. This means that it draws on multiple disciplines and looks both to the values and structures of those disciplines and to the professional world of work. It is argued that the strengthening of the epistemological base of Higher Education Studies is necessary for higher education research to move forwards with enhanced relational and positional autonomy.
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- Authors: McKenna, Sioux
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187405 , vital:44631 , xlink:href="https://hdl.handle.net/10520/EJC161436"
- Description: The field of Higher Education Studies is a rapidly growing one in South Africa and abroad but there has been little systematic review of the form this growth is taking. This article presents a case study of higher education research by considering a newly formed Higher Education Studies doctoral programme. The programme comprises 29 PhD scholars in 2014, all engaged in research on some aspect of higher education. The description of the PhD programme, the PhD scholars and what their research topics are, reveals a picture of the broad range of concerns within the field of Higher Education Studies and suggests that the field is a region, in Bernstein's terms. This means that it draws on multiple disciplines and looks both to the values and structures of those disciplines and to the professional world of work. It is argued that the strengthening of the epistemological base of Higher Education Studies is necessary for higher education research to move forwards with enhanced relational and positional autonomy.
- Full Text: