The potential of Elephantorrhiza elephantina as an anthelmintic of goats in the Eastern Cape province, South Africa
- Authors: Mazhangara, Irene Rumbidza
- Date: 2017
- Subjects: Bioactive compounds -- South Africa -- Eastern Cape Medicinal plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15068 , vital:40160
- Description: The main objective of the study was to investigate the potential of Elephantorrhiza elephantina in the control of gastro-intestinal worms in goats in the Eastern Cape Province, South Africa. The ethanolic, methanolic and aqueous phytochemical composition of E. elephantina root bark extracts were determined. The phytochemical analysis revealed a high concentration of alkaloids, condensed tannins, flavonoids, phenols and saponins in E. elephantina root extracts. Quantitative phytochemical analysis of alkaloids in water extract was 932.44 ± 1.23 mg. Condensed tannins, phenols and saponins in ethanol extract were 450.52 ± 4.56 mg CE/g, 476.11 ± 0.03 mg GAE/g and 832.85 ± 1.45 mg respectively. Flavonoids was 803.93 ± 0.02 mg QE/g in methanol extract as the highest recordings. In vitro screening of ethanol, methanol and water extracts of E. elephantina for potential anthelminthic activity against adult Paramphistomum cervi worm motility showed time and dose-dependent significant effects after 12 hours of treatment. Ethanolic extracts showed a highly significant (P < 0.05) inhibition of motility (86.67 and 96.67 percent) at concentrations 7.5 and 15 mg/ml, respectively. Methanolic and aqueous extracts exhibited a significant (P < 0.05) motility inhibition (96.67 and 66.67 percent, respectively) at concentration of 15 mg/ml 16 hours post-exposure. In vitro assessment of structural changes to adult gastro-intestinal worms following exposure to E. elephantina extracts was done using scanning electron microscopy (SEM). The SEM observations revealed structural changes in the worms after contact with E. elephantina extracts in comparison with the control worms kept in Phosphate-buffered saline (PBS). The major alterations were around the cuticle, posterior and anterior areas. These changes included longitudinal and transversal folds and thicker cuticula ridges, material aggregates around the posterior and anterior areas. The study showed that ethanol, methanol and water extracts of E. elephantina root contained significant amounts of alkaloids, condensed tannins, flavanoids, phenols and saponins. Validation studies showed that extracts of E. elephantina possess anthelminthic activities. The structural changes found in the worms exposed to extracts of E. elephantina root extracts affected their motility and nutrition, resulting in mortality.
- Full Text:
- Date Issued: 2017
- Authors: Mazhangara, Irene Rumbidza
- Date: 2017
- Subjects: Bioactive compounds -- South Africa -- Eastern Cape Medicinal plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15068 , vital:40160
- Description: The main objective of the study was to investigate the potential of Elephantorrhiza elephantina in the control of gastro-intestinal worms in goats in the Eastern Cape Province, South Africa. The ethanolic, methanolic and aqueous phytochemical composition of E. elephantina root bark extracts were determined. The phytochemical analysis revealed a high concentration of alkaloids, condensed tannins, flavonoids, phenols and saponins in E. elephantina root extracts. Quantitative phytochemical analysis of alkaloids in water extract was 932.44 ± 1.23 mg. Condensed tannins, phenols and saponins in ethanol extract were 450.52 ± 4.56 mg CE/g, 476.11 ± 0.03 mg GAE/g and 832.85 ± 1.45 mg respectively. Flavonoids was 803.93 ± 0.02 mg QE/g in methanol extract as the highest recordings. In vitro screening of ethanol, methanol and water extracts of E. elephantina for potential anthelminthic activity against adult Paramphistomum cervi worm motility showed time and dose-dependent significant effects after 12 hours of treatment. Ethanolic extracts showed a highly significant (P < 0.05) inhibition of motility (86.67 and 96.67 percent) at concentrations 7.5 and 15 mg/ml, respectively. Methanolic and aqueous extracts exhibited a significant (P < 0.05) motility inhibition (96.67 and 66.67 percent, respectively) at concentration of 15 mg/ml 16 hours post-exposure. In vitro assessment of structural changes to adult gastro-intestinal worms following exposure to E. elephantina extracts was done using scanning electron microscopy (SEM). The SEM observations revealed structural changes in the worms after contact with E. elephantina extracts in comparison with the control worms kept in Phosphate-buffered saline (PBS). The major alterations were around the cuticle, posterior and anterior areas. These changes included longitudinal and transversal folds and thicker cuticula ridges, material aggregates around the posterior and anterior areas. The study showed that ethanol, methanol and water extracts of E. elephantina root contained significant amounts of alkaloids, condensed tannins, flavanoids, phenols and saponins. Validation studies showed that extracts of E. elephantina possess anthelminthic activities. The structural changes found in the worms exposed to extracts of E. elephantina root extracts affected their motility and nutrition, resulting in mortality.
- Full Text:
- Date Issued: 2017
Assessing MODIS evapotranspiration data for hydrological modelling in South Africa
- Mazibuko, Sbongiseni Christian
- Authors: Mazibuko, Sbongiseni Christian
- Date: 2017
- Subjects: Evapotranspiration , Evapotranspiration -- Measurement , Hydrologic models , Hydrologic models -- South Africa , MODIS (Spectroradiometer)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8009 , vital:21334
- Description: Evapotranspiration as a major component of the water balance has been identified as a key factor in hydrological modelling. Water management can be improved by means of increased use of reliable methods for estimating evapotranspiration. The limited availability of measured climate and discharge data sets, particularly in the developing world, restricts the reliability of hydrological models in these regions. Furthermore, rapid changes in hydrological systems with increasing development mean uncertainties in water resource estimation are growing. These changes are related to the modification of catchment hydrological processes with increasing human activity. Dealing with data uncertainty and quantifying the impacts of catchment activities are significant challenges that scientists in the field of hydrology face today. Uncertainties in hydrometeorological data are associated with poor observation networks that provide data at point scales which are not adequately representative of the inherent heterogeneity within catchment processes. Using uncertain data in model applications reduces the predictive power of hydrological models as well as the ability to validate the model outcomes. This study examines the potential of using remote sensing-based evapotranspiration data to reduce uncertainty in the climatic forcing data and constraining the output of a rainfall-runoff hydrological model. It is common to use fixed seasonally variable potential evapotranspiration (PET) instead of temporally varying PET data as inputs to standard rainfall-runoff models. Part of the reason is that there are relatively few stations available to measure a variety of meteorological input data needed to compute PET, as well as the apparent lack of sensitivity of rainfall-runoff models to different types of PET inputs. As hydrometeorological data become more readily available through the use of earth observation systems, it is important to determine whether rainfall-runoff models are sensitive to time-varying PET derived from these earth observations systems. Further potential includes the use of actual evapotranspiration (ETa) from this type of data to constrain model outputs and improve model realism. It is assumed that a better representation of evapotranspiration demands could improve the efficiency of models, and this study explores some of these issues. The study used evapotranspiration estimates (PET and ETa) from the MOD16 global product with one of the most widely used hydrological models in South Africa. The investigation included applying the Pitman model in a number of case study catchments located in different climatic regions of the country. The main objectives of the study included (i) the establishment of behavioural model parameter sets that generate acceptable hydrological response under both naturalised and present-day conditions, (ii) the use of time-varying PET estimates derived from MOD16 data to force the model, and (iii) the use of MOD16 ETa estimates to constrain model-simulated ETa. Before examining the use of different PET forcing data in the model, a two-step modelling approached was employed both a single-run and an uncertainty version of the Pitman model. During the first step (using a single-run version), available information on catchment physical properties and regionalised groundwater recharge together with model calibration principles were used to develop model functionality understanding and establish initial parameter sets. The outcomes from the first step were used to define uncertain parameter ranges for the use in the uncertainty version of the Pitman model (second step). Further, catchment water uses were quantified to ensure comparability with present-day flow conditions represented by the stream flow records. The effects of forcing the Pitman model with MOD16-based time-varying PET data inputs were evaluated using static and dynamic sensitivity analysis approaches. In the static approach, parameter sets calibrated using fixed seasonal distributions of PET data remain unchanged when forcing the model with other forms of PET, whereas in the dynamic method, the model is recalibrated with changing PET inputs. In both approaches, model sensitivity was assessed by comparing objective function statistics of reference flow simulations with those simulations incorporating changing PET data inputs. The use of the MOD16 ETa data to constrain model- simulated evapotranspiration losses was conducted by calibrating the parameters such that the simulated-ETa matched the evapotranspiration loss estimated from the MOD16 data. Despite issues around model equifinality and significant uncertainty within water use information, the Pitman model simulations were generally satisfactory and compared with observed stream flow data where available. The use of time-varying PET data does not improve the efficiency of the model when both static and dynamic sensitivity approaches are used. This was highly expected with the static approach where fixed model parameter sets do not account for the changes in evapotranspiration demands. However, with the dynamic approach, it was difficult to conclude why the model efficiency did not improve given the flexibility of the model to achieve appropriate parameter sets to different forms of PET. The study noted that the insensitivity of the model to changes in PET demands could be due to uncertainties in the model structure and MOD16 data. Attempts to constrain the model-simulated actual evapotranspiration with MOD16 ETa estimates were hampered by large errors in the MOD16 data and resulted in the non-closure of the catchment annual water balance, even when likely errors in the other components of the water balance were accounted for. There is still a great deal of work that needs to be done to reduce uncertainties associated with the use of earth observation data in hydrological modelling. This study has identified some of the specific gaps within the application of evapotranspiration data from earth observation information. While the MOD16 data applied with the Pitman model did not achieve improved simulations, the study has demonstrated the enormous potential of the data product in the future should the identified uncertainties be resolved. Lastly, the investigation highlighted some of the possible model structural uncertainties specifically associated with the simplified soil-moisture accounting routines within the model. It is possible that amending the model structure through investigating the dynamics of the relationship between soil moisture and evapotranspiration losses would assist in the improved utilisation of earth observation products related to the MOD16 ET data.
- Full Text:
- Date Issued: 2017
- Authors: Mazibuko, Sbongiseni Christian
- Date: 2017
- Subjects: Evapotranspiration , Evapotranspiration -- Measurement , Hydrologic models , Hydrologic models -- South Africa , MODIS (Spectroradiometer)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8009 , vital:21334
- Description: Evapotranspiration as a major component of the water balance has been identified as a key factor in hydrological modelling. Water management can be improved by means of increased use of reliable methods for estimating evapotranspiration. The limited availability of measured climate and discharge data sets, particularly in the developing world, restricts the reliability of hydrological models in these regions. Furthermore, rapid changes in hydrological systems with increasing development mean uncertainties in water resource estimation are growing. These changes are related to the modification of catchment hydrological processes with increasing human activity. Dealing with data uncertainty and quantifying the impacts of catchment activities are significant challenges that scientists in the field of hydrology face today. Uncertainties in hydrometeorological data are associated with poor observation networks that provide data at point scales which are not adequately representative of the inherent heterogeneity within catchment processes. Using uncertain data in model applications reduces the predictive power of hydrological models as well as the ability to validate the model outcomes. This study examines the potential of using remote sensing-based evapotranspiration data to reduce uncertainty in the climatic forcing data and constraining the output of a rainfall-runoff hydrological model. It is common to use fixed seasonally variable potential evapotranspiration (PET) instead of temporally varying PET data as inputs to standard rainfall-runoff models. Part of the reason is that there are relatively few stations available to measure a variety of meteorological input data needed to compute PET, as well as the apparent lack of sensitivity of rainfall-runoff models to different types of PET inputs. As hydrometeorological data become more readily available through the use of earth observation systems, it is important to determine whether rainfall-runoff models are sensitive to time-varying PET derived from these earth observations systems. Further potential includes the use of actual evapotranspiration (ETa) from this type of data to constrain model outputs and improve model realism. It is assumed that a better representation of evapotranspiration demands could improve the efficiency of models, and this study explores some of these issues. The study used evapotranspiration estimates (PET and ETa) from the MOD16 global product with one of the most widely used hydrological models in South Africa. The investigation included applying the Pitman model in a number of case study catchments located in different climatic regions of the country. The main objectives of the study included (i) the establishment of behavioural model parameter sets that generate acceptable hydrological response under both naturalised and present-day conditions, (ii) the use of time-varying PET estimates derived from MOD16 data to force the model, and (iii) the use of MOD16 ETa estimates to constrain model-simulated ETa. Before examining the use of different PET forcing data in the model, a two-step modelling approached was employed both a single-run and an uncertainty version of the Pitman model. During the first step (using a single-run version), available information on catchment physical properties and regionalised groundwater recharge together with model calibration principles were used to develop model functionality understanding and establish initial parameter sets. The outcomes from the first step were used to define uncertain parameter ranges for the use in the uncertainty version of the Pitman model (second step). Further, catchment water uses were quantified to ensure comparability with present-day flow conditions represented by the stream flow records. The effects of forcing the Pitman model with MOD16-based time-varying PET data inputs were evaluated using static and dynamic sensitivity analysis approaches. In the static approach, parameter sets calibrated using fixed seasonal distributions of PET data remain unchanged when forcing the model with other forms of PET, whereas in the dynamic method, the model is recalibrated with changing PET inputs. In both approaches, model sensitivity was assessed by comparing objective function statistics of reference flow simulations with those simulations incorporating changing PET data inputs. The use of the MOD16 ETa data to constrain model- simulated evapotranspiration losses was conducted by calibrating the parameters such that the simulated-ETa matched the evapotranspiration loss estimated from the MOD16 data. Despite issues around model equifinality and significant uncertainty within water use information, the Pitman model simulations were generally satisfactory and compared with observed stream flow data where available. The use of time-varying PET data does not improve the efficiency of the model when both static and dynamic sensitivity approaches are used. This was highly expected with the static approach where fixed model parameter sets do not account for the changes in evapotranspiration demands. However, with the dynamic approach, it was difficult to conclude why the model efficiency did not improve given the flexibility of the model to achieve appropriate parameter sets to different forms of PET. The study noted that the insensitivity of the model to changes in PET demands could be due to uncertainties in the model structure and MOD16 data. Attempts to constrain the model-simulated actual evapotranspiration with MOD16 ETa estimates were hampered by large errors in the MOD16 data and resulted in the non-closure of the catchment annual water balance, even when likely errors in the other components of the water balance were accounted for. There is still a great deal of work that needs to be done to reduce uncertainties associated with the use of earth observation data in hydrological modelling. This study has identified some of the specific gaps within the application of evapotranspiration data from earth observation information. While the MOD16 data applied with the Pitman model did not achieve improved simulations, the study has demonstrated the enormous potential of the data product in the future should the identified uncertainties be resolved. Lastly, the investigation highlighted some of the possible model structural uncertainties specifically associated with the simplified soil-moisture accounting routines within the model. It is possible that amending the model structure through investigating the dynamics of the relationship between soil moisture and evapotranspiration losses would assist in the improved utilisation of earth observation products related to the MOD16 ET data.
- Full Text:
- Date Issued: 2017
The impact of rangeland degradation on vegetation cover and soil quality in semi-arid communal rangelands of the Eastern Cape province, South Africa
- Authors: Maziko, Yonela
- Date: 2017
- Subjects: Communal rangelands -- South Africa -- Eastern Cape Land degradation -- South Africa -- Eastern Cape Vegetation management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15056 , vital:40159
- Description: This study was conducted to investigate the influence of degradation on vegetation and soil quality in two semi-arid rangelands in the Eastern Cape Province of South Africa. The study was undertaken in Kwezana and Esigingqini communal areas that showed signs id degradation. The assessment incorporated the soil and grass layer in different degradation levels, namely nondegraded, slightly degraded, moderately and severely degraded. The non-degraded has a sufficient amount of vegetation cover and species composition. The slightly degraded site consists of a few visible bare patches. The moderately degraded areas showed signs of active sheet erosion such as pedestals and a higher percentage of bare areas and the severely degraded area is characterized by dongas and gullies, with vast areas that have no ground cover or top fertile soil layer. Using a step point method, herbaceous species composition was determined within three transects from three plots 100 m x 40 m in each degradation level. The aboveground phytomass production was determined by harvesting herbaceous species within four randomly placed 0.25 m2 quadrats in each transect. Bare ground was determined by counting and recording the distance between tufts within each quadrat. Litter cover was determined by visual observation and rated on a scale of 1 to 5. A number of physical and chemical soil properties were used to quantify the effects of degradation on soil quality. To determine soil chemical properties, three soil samples were collected at a depth of 20 cm, in each plot and analyzed for pH, soil macro (N, C, K, P, Ca, Mg) and micro (Zn, Fe, Mn and Cu) nutrients. Soil compaction was determined using a soil pocket penetrometer. Readings were taken at 5 mm from 30 points placed at 1 m intervals and distributed in a randomly established straight line in each plot. Soil loss was determined using a rainfall simulator. Splash cups were filled with soil and placed under the rainfall simulator for 8 minutes per rainstorm at 360 mm-1 intensity. Results showed that at Esigingqini a total of 20 herbaceous species were identified, 17 of which were grasses. About 60percent of the identified grasses were Increaser II species, 15percent were Increaser II and 25percent Decreasers. In terms of palatability, 50percent of the grass species had poor palatability and the remaining had either average or high palatability. At Kwezana, 18 herbaceous species were identified of which 28percent were Decreasers and 61percent were Increaser II species. Half of the species had low palatability and only 28percent had high palatability. In both communal areas, litter cover was highest (P < 0.05) in the non-degraded areas followed by the slightly degraded sites and this was to be expected. Similarly, in both communal areas, there was a shift in species composition of decreasers and perennial grasses being replaced by annual species of poor quality and low palatability as the degradation levels increased. Results on soil chemical properties showed that the non-degraded areas had higher (P < 0.05) pH levels (8.5) than the severely degraded soils (5). A similar trend following a degradation gradient was observed for some soil nutrients such as N, P or Mg. Both the macro and micro nutrient concentrations were relatively higher (P < 0.05) in summer than in winter in both communal areas. Results on physical properties showed that soil loss and compaction were relatively lower (P <0.05) in the slightly degraded and non-degraded sites and increased with severity of degradation. In both communal areas, the severely degraded areas lost soil up to 1.1 t ha-1 due to degradation and the non-degraded areas had a soil loss of less than 0.8 t ha-1. The rate of soil loss between the severely and non-degraded areas is significantly different. The differences may be attributed to the differences in the vegetation cover which influences the rate of erosion on the various degradation gradients. These results suggest that both the grass layer and soil quality is negatively affected by degradation. Therefore, there is a need for land use practices that promote the sustainable use of rangeland resources. Such practices may include rotational grazing, reseeding, veld resting and fire. Measures to control the consequences of degradation and rehabilitate these deteriorated rangelands must be a priority.
- Full Text:
- Date Issued: 2017
- Authors: Maziko, Yonela
- Date: 2017
- Subjects: Communal rangelands -- South Africa -- Eastern Cape Land degradation -- South Africa -- Eastern Cape Vegetation management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15056 , vital:40159
- Description: This study was conducted to investigate the influence of degradation on vegetation and soil quality in two semi-arid rangelands in the Eastern Cape Province of South Africa. The study was undertaken in Kwezana and Esigingqini communal areas that showed signs id degradation. The assessment incorporated the soil and grass layer in different degradation levels, namely nondegraded, slightly degraded, moderately and severely degraded. The non-degraded has a sufficient amount of vegetation cover and species composition. The slightly degraded site consists of a few visible bare patches. The moderately degraded areas showed signs of active sheet erosion such as pedestals and a higher percentage of bare areas and the severely degraded area is characterized by dongas and gullies, with vast areas that have no ground cover or top fertile soil layer. Using a step point method, herbaceous species composition was determined within three transects from three plots 100 m x 40 m in each degradation level. The aboveground phytomass production was determined by harvesting herbaceous species within four randomly placed 0.25 m2 quadrats in each transect. Bare ground was determined by counting and recording the distance between tufts within each quadrat. Litter cover was determined by visual observation and rated on a scale of 1 to 5. A number of physical and chemical soil properties were used to quantify the effects of degradation on soil quality. To determine soil chemical properties, three soil samples were collected at a depth of 20 cm, in each plot and analyzed for pH, soil macro (N, C, K, P, Ca, Mg) and micro (Zn, Fe, Mn and Cu) nutrients. Soil compaction was determined using a soil pocket penetrometer. Readings were taken at 5 mm from 30 points placed at 1 m intervals and distributed in a randomly established straight line in each plot. Soil loss was determined using a rainfall simulator. Splash cups were filled with soil and placed under the rainfall simulator for 8 minutes per rainstorm at 360 mm-1 intensity. Results showed that at Esigingqini a total of 20 herbaceous species were identified, 17 of which were grasses. About 60percent of the identified grasses were Increaser II species, 15percent were Increaser II and 25percent Decreasers. In terms of palatability, 50percent of the grass species had poor palatability and the remaining had either average or high palatability. At Kwezana, 18 herbaceous species were identified of which 28percent were Decreasers and 61percent were Increaser II species. Half of the species had low palatability and only 28percent had high palatability. In both communal areas, litter cover was highest (P < 0.05) in the non-degraded areas followed by the slightly degraded sites and this was to be expected. Similarly, in both communal areas, there was a shift in species composition of decreasers and perennial grasses being replaced by annual species of poor quality and low palatability as the degradation levels increased. Results on soil chemical properties showed that the non-degraded areas had higher (P < 0.05) pH levels (8.5) than the severely degraded soils (5). A similar trend following a degradation gradient was observed for some soil nutrients such as N, P or Mg. Both the macro and micro nutrient concentrations were relatively higher (P < 0.05) in summer than in winter in both communal areas. Results on physical properties showed that soil loss and compaction were relatively lower (P <0.05) in the slightly degraded and non-degraded sites and increased with severity of degradation. In both communal areas, the severely degraded areas lost soil up to 1.1 t ha-1 due to degradation and the non-degraded areas had a soil loss of less than 0.8 t ha-1. The rate of soil loss between the severely and non-degraded areas is significantly different. The differences may be attributed to the differences in the vegetation cover which influences the rate of erosion on the various degradation gradients. These results suggest that both the grass layer and soil quality is negatively affected by degradation. Therefore, there is a need for land use practices that promote the sustainable use of rangeland resources. Such practices may include rotational grazing, reseeding, veld resting and fire. Measures to control the consequences of degradation and rehabilitate these deteriorated rangelands must be a priority.
- Full Text:
- Date Issued: 2017
An analysis of flood activity over the past century based on the sedimentary deposits in the Mfolozi floodplain
- Authors: Mbao, Chabala
- Date: 2017
- Subjects: Floodplain morphology -- South Africa -- Mfolozi River , Floodplains -- South Africa -- Kwazulu-Natal , Sedimentation and deposition -- South Africa -- Kwazulu-Natal , Floods -- South Africa -- Kwazulu-Natal -- Measurement , Hydrology -- Research -- South Africa -- Kwazulu-Natal , Stream measurements -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/53711 , vital:26312
- Description: Floods are natural phenomena that are of widespread interest to the scientific community, particularly in the context of understanding the impact of climate change as well as changing land use patterns and the security of infrastructure such as towns and roads. In northern KwaZulu-Natal, large flood events have been a reoccurring feature over the past century. The geographical position and extent of the region means that is affected by both inland and coastal weather phenomena, each with the potential to cause large flood events. While information pertaining to large floods in the region in the form of flow data is readily available, flow data is often incomplete and limited in terms of how far back in time the records extend. The Mfolozi River floodplain itself also houses a record of flood activity in the region in the form of sedimentary deposits, which have the potential to reveal flood activity over a much longer timescale, even when monitoring of flood activity in the region was not present. Establishing a link between the hydrological and sedimentary features of floods may be useful in establishing a record of flood activity extending beyond the limits of historical records. The aim of this project was to construct a record of major flood events on the Mfolozi River floodplain over the last century and determine their source. The first objective involved establishing the history of flood events in the Mfolozi River catchment utilising hydrological data recorded throughout the catchment. Thirty nine different large floods (defined as being over 800 m3.s-1) were recorded on the floodplain over the past century. The data also highlighted differences in the extent of known coastal and inland systems (tropical cyclones and cut-off lows respectively), allowing for inferences to be made about the area of the catchment most likely affected by each event; some flood events were identified as having mostly affected the upper reaches of the catchment, while others mostly affected the lower reaches, closer to the coast. The second objective was to identify the various physical, mineralogical and geochemical features of the sediment deposited on the Mfolozi floodplain. Multiple individual flood deposits were identified in the sedimentary record, with sediment tracing analysis providing insight into the source of the deposits within the catchment; no traces of igneous or metamorphic material could be found within the sediment. The source rocks were identified as mostly quartzite, with minor shale and sandstone deposits as well. This put the source of the sediment in the upper to middle reaches of the catchment. The sedimentary analysis was combined with the hydrological records to establish a chronology of flood events extending back to the 1960's. Unfortunately, this record could not be extended further due to the limited amount of sediment collected as well the limits of readily available analytical techniques; radionuclide dating methods were unsuccessful due to the low amounts of fallout radionuclides present in the sediment. The study has however successfully established a history of flood events in the region, as well as providing a link between the hydrological and sedimentary features of flood events that could potentially be useful for current and future research.
- Full Text:
- Date Issued: 2017
- Authors: Mbao, Chabala
- Date: 2017
- Subjects: Floodplain morphology -- South Africa -- Mfolozi River , Floodplains -- South Africa -- Kwazulu-Natal , Sedimentation and deposition -- South Africa -- Kwazulu-Natal , Floods -- South Africa -- Kwazulu-Natal -- Measurement , Hydrology -- Research -- South Africa -- Kwazulu-Natal , Stream measurements -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/53711 , vital:26312
- Description: Floods are natural phenomena that are of widespread interest to the scientific community, particularly in the context of understanding the impact of climate change as well as changing land use patterns and the security of infrastructure such as towns and roads. In northern KwaZulu-Natal, large flood events have been a reoccurring feature over the past century. The geographical position and extent of the region means that is affected by both inland and coastal weather phenomena, each with the potential to cause large flood events. While information pertaining to large floods in the region in the form of flow data is readily available, flow data is often incomplete and limited in terms of how far back in time the records extend. The Mfolozi River floodplain itself also houses a record of flood activity in the region in the form of sedimentary deposits, which have the potential to reveal flood activity over a much longer timescale, even when monitoring of flood activity in the region was not present. Establishing a link between the hydrological and sedimentary features of floods may be useful in establishing a record of flood activity extending beyond the limits of historical records. The aim of this project was to construct a record of major flood events on the Mfolozi River floodplain over the last century and determine their source. The first objective involved establishing the history of flood events in the Mfolozi River catchment utilising hydrological data recorded throughout the catchment. Thirty nine different large floods (defined as being over 800 m3.s-1) were recorded on the floodplain over the past century. The data also highlighted differences in the extent of known coastal and inland systems (tropical cyclones and cut-off lows respectively), allowing for inferences to be made about the area of the catchment most likely affected by each event; some flood events were identified as having mostly affected the upper reaches of the catchment, while others mostly affected the lower reaches, closer to the coast. The second objective was to identify the various physical, mineralogical and geochemical features of the sediment deposited on the Mfolozi floodplain. Multiple individual flood deposits were identified in the sedimentary record, with sediment tracing analysis providing insight into the source of the deposits within the catchment; no traces of igneous or metamorphic material could be found within the sediment. The source rocks were identified as mostly quartzite, with minor shale and sandstone deposits as well. This put the source of the sediment in the upper to middle reaches of the catchment. The sedimentary analysis was combined with the hydrological records to establish a chronology of flood events extending back to the 1960's. Unfortunately, this record could not be extended further due to the limited amount of sediment collected as well the limits of readily available analytical techniques; radionuclide dating methods were unsuccessful due to the low amounts of fallout radionuclides present in the sediment. The study has however successfully established a history of flood events in the region, as well as providing a link between the hydrological and sedimentary features of flood events that could potentially be useful for current and future research.
- Full Text:
- Date Issued: 2017
The growth and recovery of mangroves at three South African study sites
- Authors: Mbense, Sinegugu
- Date: 2017
- Subjects: Mangrove forests -- South Africa Mangrove ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11931 , vital:27008
- Description: Mangroves in South Africa are prone to anthropogenic pressures such as browsing and trampling by livestock and by natural disturbances such as drought and floods. These mangroves exist at one of the most southerly limits in the world providing a unique opportunity to study recovery and resilience to change. This study used long term data at three South African study sites located in the subtropical (St Lucia Estuary) and warm temperate regions (Nxaxo and Kobonqaba estuaries) to compare mangrove growth rate, population structure and responses to disturbance. The first objective was investigated at St Lucia Estuary where site specific or microhabitat differences were measured to assess the influence of these on mangrove growth and population structure. It was suggested that site - specific variability would ensure mangrove survival and analysis showed that seedlings were present at different sites in different years. There was always some recruitment but often little survival to the next size class. Over time seedling numbers were quite variable and self – thinning of adults was evident. The second objective was to identify the environmental factors influencing population density and growth. Results showed that sediment moisture and salinity influenced seedling and adult density due to fluctuations in estuary water level. Mangrove growth rates for Avicennia marina in terms of height was faster (40 – 75 cm yr-1 ) at Site 1 where conditions were waterlogged and moderately saline and slower (5 – 25 cm yr1 ) in dry and hypersaline conditions at Site 4. Overall mangroves at St Lucia have shown persistence through drought and fluctuations in environmental conditions however resilience may be hindered at sites that are subjected to partially flooding and prolonged waterlogging. The second site was Nxaxo Estuary in the Eastern Cape where cattle exclusion plots (nonbrowsed) and control plots (browsed) were used to assess the recovery of A. marina trees from cattle browsing. Trees in the browsed plots showed no vertical growth while trees in the non-browsed plots grew significantly faster (5.4 ± 0.5 cm yr-1). When cattle were prevented from entering the mangrove area, the trees recovered fairly quickly and within 3 years growth was similar in both the non – browsed (17.9 ± 3.2 cm yr -1) and browsed plots (18 ± 1.6 cm yr -1). Lastly, mangrove recovery was investigated at Kobonqaba Estuary where long-term closure of the mouth to the sea resulted in high water levels, inundation of pneumatophores and die-back of the majority of the mangroves. This study measured the recovery of the mangroves by assessing changes in vegetation cover and sediment characteristics along transects. High initial porewater nutrient concentrations promoted salt marsh growth and plants increased average cover from 0% in 2011 to 18.9% (2013) and 50% in 2015. The total number of A. marina individuals increased from only seven to 27 individuals over four years. Salt marsh competition and facilitation will likely influence mangrove recovery in the future. Overall it was concluded that when a short term pressure (cattle browsing) is alleviated, mangrove forests even at warm temperate sites are able to recovery rapidly by increasing growth and seedling establishment. However, mangroves in the subtropical sites show more resilience and recovery potential to long term pressures such as fluctuating environmental conditions because of faster growth rates.
- Full Text:
- Date Issued: 2017
- Authors: Mbense, Sinegugu
- Date: 2017
- Subjects: Mangrove forests -- South Africa Mangrove ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11931 , vital:27008
- Description: Mangroves in South Africa are prone to anthropogenic pressures such as browsing and trampling by livestock and by natural disturbances such as drought and floods. These mangroves exist at one of the most southerly limits in the world providing a unique opportunity to study recovery and resilience to change. This study used long term data at three South African study sites located in the subtropical (St Lucia Estuary) and warm temperate regions (Nxaxo and Kobonqaba estuaries) to compare mangrove growth rate, population structure and responses to disturbance. The first objective was investigated at St Lucia Estuary where site specific or microhabitat differences were measured to assess the influence of these on mangrove growth and population structure. It was suggested that site - specific variability would ensure mangrove survival and analysis showed that seedlings were present at different sites in different years. There was always some recruitment but often little survival to the next size class. Over time seedling numbers were quite variable and self – thinning of adults was evident. The second objective was to identify the environmental factors influencing population density and growth. Results showed that sediment moisture and salinity influenced seedling and adult density due to fluctuations in estuary water level. Mangrove growth rates for Avicennia marina in terms of height was faster (40 – 75 cm yr-1 ) at Site 1 where conditions were waterlogged and moderately saline and slower (5 – 25 cm yr1 ) in dry and hypersaline conditions at Site 4. Overall mangroves at St Lucia have shown persistence through drought and fluctuations in environmental conditions however resilience may be hindered at sites that are subjected to partially flooding and prolonged waterlogging. The second site was Nxaxo Estuary in the Eastern Cape where cattle exclusion plots (nonbrowsed) and control plots (browsed) were used to assess the recovery of A. marina trees from cattle browsing. Trees in the browsed plots showed no vertical growth while trees in the non-browsed plots grew significantly faster (5.4 ± 0.5 cm yr-1). When cattle were prevented from entering the mangrove area, the trees recovered fairly quickly and within 3 years growth was similar in both the non – browsed (17.9 ± 3.2 cm yr -1) and browsed plots (18 ± 1.6 cm yr -1). Lastly, mangrove recovery was investigated at Kobonqaba Estuary where long-term closure of the mouth to the sea resulted in high water levels, inundation of pneumatophores and die-back of the majority of the mangroves. This study measured the recovery of the mangroves by assessing changes in vegetation cover and sediment characteristics along transects. High initial porewater nutrient concentrations promoted salt marsh growth and plants increased average cover from 0% in 2011 to 18.9% (2013) and 50% in 2015. The total number of A. marina individuals increased from only seven to 27 individuals over four years. Salt marsh competition and facilitation will likely influence mangrove recovery in the future. Overall it was concluded that when a short term pressure (cattle browsing) is alleviated, mangrove forests even at warm temperate sites are able to recovery rapidly by increasing growth and seedling establishment. However, mangroves in the subtropical sites show more resilience and recovery potential to long term pressures such as fluctuating environmental conditions because of faster growth rates.
- Full Text:
- Date Issued: 2017
Cultural and heritage tourism trends in the Amathole District Municipality of the Eastern Cape Province, South Africa, 2004-2014
- Authors: Mboniswa, Mncedi Justice
- Date: 2017
- Subjects: Heritage tourism -- South Africa -- Eastern Cape Cultural property -- Repatriation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7897 , vital:30798
- Description: The promotion of tourism in a country, especially those with high levels of poverty is one of the strategies that can potentially improve socio-economic conditions of citizens. In South Africa, cultural and heritage tourism is seen as one of the ways in which cultural resources can be utilised to benefit marginalised communities and individuals. Such resources can also serve as source of income since both domestic and international tourists can activate industry as they are interested in learning more about other cultures and heritage. There are on-going debates, however on what constitutes cultural and heritage tourism, who it benefits and how this enterprise is located within various communities of South Africa. This research therefore aims to fill this gap through investigating cultural and heritage tourism development trends within the Amathole District Municipality (ADM) and how this development trend impacts on employment creation and improving the socio-economic conditions of citizens within this area of ADM. To realise this aim, the study looks at the availability of cultural and heritage tourism structures within the ADM and the database records on these structures. This study adopts the community benefit tourism initiatives approach to tourism development in the Amathole District Municipality of the Eastern Cape Province. This qualitative study reveals how the community benefit tourism approach encompasses rewards to local communities, in as much as it enhances sustainability of tourism initiatives. In bringing out these aspects, the study also examines efforts of the government and private sector in the up-keeping of tourism initiatives, especially for marginalised communities of South Africa.
- Full Text:
- Date Issued: 2017
- Authors: Mboniswa, Mncedi Justice
- Date: 2017
- Subjects: Heritage tourism -- South Africa -- Eastern Cape Cultural property -- Repatriation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7897 , vital:30798
- Description: The promotion of tourism in a country, especially those with high levels of poverty is one of the strategies that can potentially improve socio-economic conditions of citizens. In South Africa, cultural and heritage tourism is seen as one of the ways in which cultural resources can be utilised to benefit marginalised communities and individuals. Such resources can also serve as source of income since both domestic and international tourists can activate industry as they are interested in learning more about other cultures and heritage. There are on-going debates, however on what constitutes cultural and heritage tourism, who it benefits and how this enterprise is located within various communities of South Africa. This research therefore aims to fill this gap through investigating cultural and heritage tourism development trends within the Amathole District Municipality (ADM) and how this development trend impacts on employment creation and improving the socio-economic conditions of citizens within this area of ADM. To realise this aim, the study looks at the availability of cultural and heritage tourism structures within the ADM and the database records on these structures. This study adopts the community benefit tourism initiatives approach to tourism development in the Amathole District Municipality of the Eastern Cape Province. This qualitative study reveals how the community benefit tourism approach encompasses rewards to local communities, in as much as it enhances sustainability of tourism initiatives. In bringing out these aspects, the study also examines efforts of the government and private sector in the up-keeping of tourism initiatives, especially for marginalised communities of South Africa.
- Full Text:
- Date Issued: 2017
Calibration and imaging with variable radio sources
- Authors: Mbou Sob, Ulrich Armel
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/37977 , vital:24721
- Description: Calibration of radio interferometric data is one of the most important steps that are required to produce high dynamic range radio maps with high fidelity. However, naive calibration (inaccurate knowledge of the sky and instruments) leads to the formation of calibration artefacts: the generation of spurious sources and the deformations in the structure of extended sources. A particular class of calibration artefacts, called ghost sources, which results from calibration with incomplete sky models has been extensively studied by Grobler et al. (2014, 2016) and Wijnholds et al. (2016). They developed a framework which can be used to predict the fluxes and positions of ghost sources. This work uses the approach initiated by these authors to study the calibration artefacts and ghost sources that are produced when variable sources are not considered in sky models during calibration. This work investigates both long-term and short-term variability and uses the root mean square (rms) and power spectrum as metrics to evaluate the “quality” of the residual visibilities obtained through calibration. We show that the overestimation and underestimation of source flux density during calibration produces similar but symmetrically opposite results. We show that calibration artefacts from sky model errors are not normally distributed. This prevents them from being removed by employing advanced techniques, such as stacking. The power spectrums measured from the residuals with a variable source was significantly higher than those from residuals without a variable source. This implies advanced calibration techniques and sky model completeness will be required for studies such as probing the Epoch of Reoinization, where we seek to detect faint signals below thermal noise.
- Full Text:
- Date Issued: 2017
- Authors: Mbou Sob, Ulrich Armel
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/37977 , vital:24721
- Description: Calibration of radio interferometric data is one of the most important steps that are required to produce high dynamic range radio maps with high fidelity. However, naive calibration (inaccurate knowledge of the sky and instruments) leads to the formation of calibration artefacts: the generation of spurious sources and the deformations in the structure of extended sources. A particular class of calibration artefacts, called ghost sources, which results from calibration with incomplete sky models has been extensively studied by Grobler et al. (2014, 2016) and Wijnholds et al. (2016). They developed a framework which can be used to predict the fluxes and positions of ghost sources. This work uses the approach initiated by these authors to study the calibration artefacts and ghost sources that are produced when variable sources are not considered in sky models during calibration. This work investigates both long-term and short-term variability and uses the root mean square (rms) and power spectrum as metrics to evaluate the “quality” of the residual visibilities obtained through calibration. We show that the overestimation and underestimation of source flux density during calibration produces similar but symmetrically opposite results. We show that calibration artefacts from sky model errors are not normally distributed. This prevents them from being removed by employing advanced techniques, such as stacking. The power spectrums measured from the residuals with a variable source was significantly higher than those from residuals without a variable source. This implies advanced calibration techniques and sky model completeness will be required for studies such as probing the Epoch of Reoinization, where we seek to detect faint signals below thermal noise.
- Full Text:
- Date Issued: 2017
Estimating maize grain yield from crop growth stages using remote sensing and GIS in the Free State Province, South Africa
- Authors: Mditshwa, Sithembele
- Date: 2017
- Subjects: Crop yields Crops -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6016 , vital:29481
- Description: Early yield prediction of a maize crop is important for planning and policy decisions. Many countries, including South Africa use the conventional techniques of data collection for maize crop monitoring and yield estimation which are based on ground-based visits and reports. These methods are subjective, very costly and time consuming. Empirical models have been developed using weather data. These are also associated with a number of problems due to the limited spatial distribution of weather stations. Efforts are being made to improve the accuracy and timeliness of yield prediction methods. With the launching of satellites, satellite data are being used for maize crop monitoring and yield prediction. Many studies have revealed that there is a correlation between remotely sensed data (vegetation indices) and crop yields. The satellite based approaches are less expensive, save time, data acquisition covers large areas and can be used to estimate maize grain yields before harvest. This study applied Landsat 8 satellite based vegetation indices, Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and Moisture Stress Index (MSI) to predict maize crop yield. These vegetation indices were derived at different growth stages. The investigation was carried out in the Kopanong Local Municipality of the Free State Province, South Africa. Ground-based data (actual harvested maize yields) was collected from Department of Agriculture, Forestry and Fisheries (DAFF). Satellite images were acquired from Geoterra Image (Pty) Ltd and weather data was from the South African Weather Service (SAWS). Multilinear regression approaches were used to relate yields to the remotely sensed indices and meteorological data was used during the development of yield estimation models. The results showed that there are significant correlations between remotely sensed vegetation indices and maize grain yield; up to 63 percent maize yield was predicted from vegetation indices. The study also revealed that NDVI and SAVI are better yield predictors at reproductive growth stages of maize and MSI is a better index to estimate maize yield at both vegetative and reproductive growth stages. The results obtained in this study indicated that maize grain yields can be estimated using satellite indices at different maize growth stages.
- Full Text:
- Date Issued: 2017
- Authors: Mditshwa, Sithembele
- Date: 2017
- Subjects: Crop yields Crops -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6016 , vital:29481
- Description: Early yield prediction of a maize crop is important for planning and policy decisions. Many countries, including South Africa use the conventional techniques of data collection for maize crop monitoring and yield estimation which are based on ground-based visits and reports. These methods are subjective, very costly and time consuming. Empirical models have been developed using weather data. These are also associated with a number of problems due to the limited spatial distribution of weather stations. Efforts are being made to improve the accuracy and timeliness of yield prediction methods. With the launching of satellites, satellite data are being used for maize crop monitoring and yield prediction. Many studies have revealed that there is a correlation between remotely sensed data (vegetation indices) and crop yields. The satellite based approaches are less expensive, save time, data acquisition covers large areas and can be used to estimate maize grain yields before harvest. This study applied Landsat 8 satellite based vegetation indices, Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI) and Moisture Stress Index (MSI) to predict maize crop yield. These vegetation indices were derived at different growth stages. The investigation was carried out in the Kopanong Local Municipality of the Free State Province, South Africa. Ground-based data (actual harvested maize yields) was collected from Department of Agriculture, Forestry and Fisheries (DAFF). Satellite images were acquired from Geoterra Image (Pty) Ltd and weather data was from the South African Weather Service (SAWS). Multilinear regression approaches were used to relate yields to the remotely sensed indices and meteorological data was used during the development of yield estimation models. The results showed that there are significant correlations between remotely sensed vegetation indices and maize grain yield; up to 63 percent maize yield was predicted from vegetation indices. The study also revealed that NDVI and SAVI are better yield predictors at reproductive growth stages of maize and MSI is a better index to estimate maize yield at both vegetative and reproductive growth stages. The results obtained in this study indicated that maize grain yields can be estimated using satellite indices at different maize growth stages.
- Full Text:
- Date Issued: 2017
Maize stalk fibre reinforced natural rubber/tyre-tread reclaimed rubber composites
- Authors: Mente, Pumza
- Date: 2017
- Subjects: Polymeric composites Rubber
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19332 , vital:28852
- Description: This research project focuses on the production of reclaimed rubber composites reinforced with natural fibres obtained from agricultural waste. The prepared natural fibre composites were characterized through evaluation of curing characteristics, tensile properties, thermal properties, dynamic mechanical properties and electron microscopy imaging. Untreated composites generally showed poor properties which were attributed to poor compatibility and fibre agglomeration. Various treatments were then employed in attempts to improve the composite properties. Fibre treatments used were water treatment and silane treatments using two different silane coupling agents. Torque, reaction rate and tensile modulus were observed to increase with addition of reclaimed rubber and natural fibres. Tensile strength and elongation at break increased with addition of natural rubber. An increase in thermal stability was observed with addition of reclaimed rubber. Dynamic mechanical analysis (DMA) results have shown that addition of reclaimed rubber resulted to an increase in glass transition temperature. Scanning electron microscopy (SEM) images of tensile fractured composites showed evidence of fibre pull-outs from the matrix. Removal of lignin from treated natural fibres was evident from thermogravimetric analysis (TGA) for all fibre treatments. There were no noticeable improvements in composites properties with use of fibre treatments and there were no statistical differences observed among the different fibre treatments. Generally, the composites prepared showed high stiffness and low tensile strength.
- Full Text:
- Date Issued: 2017
- Authors: Mente, Pumza
- Date: 2017
- Subjects: Polymeric composites Rubber
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19332 , vital:28852
- Description: This research project focuses on the production of reclaimed rubber composites reinforced with natural fibres obtained from agricultural waste. The prepared natural fibre composites were characterized through evaluation of curing characteristics, tensile properties, thermal properties, dynamic mechanical properties and electron microscopy imaging. Untreated composites generally showed poor properties which were attributed to poor compatibility and fibre agglomeration. Various treatments were then employed in attempts to improve the composite properties. Fibre treatments used were water treatment and silane treatments using two different silane coupling agents. Torque, reaction rate and tensile modulus were observed to increase with addition of reclaimed rubber and natural fibres. Tensile strength and elongation at break increased with addition of natural rubber. An increase in thermal stability was observed with addition of reclaimed rubber. Dynamic mechanical analysis (DMA) results have shown that addition of reclaimed rubber resulted to an increase in glass transition temperature. Scanning electron microscopy (SEM) images of tensile fractured composites showed evidence of fibre pull-outs from the matrix. Removal of lignin from treated natural fibres was evident from thermogravimetric analysis (TGA) for all fibre treatments. There were no noticeable improvements in composites properties with use of fibre treatments and there were no statistical differences observed among the different fibre treatments. Generally, the composites prepared showed high stiffness and low tensile strength.
- Full Text:
- Date Issued: 2017
Influence of sedimentological and hydrological processes on the distribution of the Spartina maritima salt marsh in the Keurbooms Estuary, Western Cape
- Authors: Mfikili, Athi Nkosibonile
- Date: 2017
- Subjects: Salt marshes -- South Africa -- Western Cape Estuarine hydrology -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13004 , vital:27143
- Description: Salt marshes are some of the most productive ecosystems in the world and have been the centre of attention over the past few decades, due to their decline as a result of global climate change and anthropogenic impacts. The growth of salt marshes is determined by substrate type, soil conductivity and elevation. The permanently open Keurbooms Estuary along the south-east coast of South Africa is subjected to occasional fluvial flooding and its intertidal area lacks well developed salt marshes, with Spartina maritima restricted to the lower reaches of the Bitou tributary and a few sections of the Keurbooms tributary. Presumeably because of fine sediment habitat in the confluence and lower Bitou tributary. The salinity of the estuarine water ranges between 0.1 – 26.9 and 3.2 – 35.3 in the Bitou and Keurbooms tributaries respectively. A typical salt wedge salinity pattern is common in the Keurbooms tributary where saline water often intrudes underneath the freshwater, especially during high river flows. The following hypotheses were developed and tested in this study: The limited spatial distribution of S. maritima in the Keurbooms Estuary is due to limited availability of fine sediment habitat; and the source of the fine sediment in the estuary is the Bitou tributary rather than the Keurbooms tributary or the sea. It was further postulated that after sediment characteristics, floods are the major hydrological driver determining the distribution of S. maritima in the Keurbooms Estuary. The results of the surveys of the estuarine channel bottom sediments showed that the Keurbooms tributary was mostly characterized by the sand-size sediment fraction derived from the feldspathic and sandstone with evidence of fine sediment fractions restricted to the upper reaches at the confluence with Whiskey Creek. The Bitou was almost always composed of coarse sized sediments in the upper reaches, fine sediment deposits in the middle and lower reaches and medium sorted sand with almost no clay or calcium carbonate in the estuarine component below the confluence of the tributaries. These findings were further supported by the surface sediment deposited within the S. maritima intertidal salt marsh, which showed finer sediment deposits in the Bitou marsh compared to the Keurbooms marsh surface. Similar results were also found in the sediment cores, with the Keurbooms marsh sediment becoming finer with increasing depth whereas fine sediments reduced with depth in the Bitou marsh. The results of the sediment mineralogy indicated that the increased concentrations of clay minerals in the S. maritima surface sediments are derived from the Bokkeveld shale, siltstone and clay slate exposed above the N2 Bridge in the Keurbooms Estuary. GIS mapping shows that S. maritima has been declining over the past two decades, with rapid decreases especially evident after big flooding events. The GIS mapping also indicates that the patches of the S. maritima in the Keurbooms tributary are more exposed to big floods than the Bitou marsh. Despite showing an overall decline, S. maritima area coverage remained more consistent in the lower reaches of the Bitou tributary than in the Keurbooms tributary. Despite the larger and more persistent area cover, the S. maritima plants were shorter and less dense than the plants growing in the sandy substrate. The black/grey colouration of soil with increasing depth in the Bitou tributary was an indication of the reduced state of the soil caused by prolonged waterlogged conditions. The roots of S. maritima in both tributaries were mostly restricted to the sub-surface substrate layer (i.e. 0 – 0.25 m), although the Bitou populations showed more vegetative propagation than the Keurbooms populations. This mechanism of reproduction was also demonstrated during the transplant experiment which showed a greater number of new stem production in the fine sediment substrates compared to the sandy silt substrates. Although accretion rates were not determined in this study, the short-term sediment deposition rates revealed that sedimentation is active in the marshes of the Keurbooms Estuary. Therefore, in spite of showing a decline in area cover, the production of viable seed and observed vegetative propagation suggest that the S. maritima is likely to colonize open stable intertidal mudflats / sandflats, thus maintaining its distribution as an intertidal species in the salt marshes of the Keurbooms Estuary.
- Full Text:
- Date Issued: 2017
- Authors: Mfikili, Athi Nkosibonile
- Date: 2017
- Subjects: Salt marshes -- South Africa -- Western Cape Estuarine hydrology -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13004 , vital:27143
- Description: Salt marshes are some of the most productive ecosystems in the world and have been the centre of attention over the past few decades, due to their decline as a result of global climate change and anthropogenic impacts. The growth of salt marshes is determined by substrate type, soil conductivity and elevation. The permanently open Keurbooms Estuary along the south-east coast of South Africa is subjected to occasional fluvial flooding and its intertidal area lacks well developed salt marshes, with Spartina maritima restricted to the lower reaches of the Bitou tributary and a few sections of the Keurbooms tributary. Presumeably because of fine sediment habitat in the confluence and lower Bitou tributary. The salinity of the estuarine water ranges between 0.1 – 26.9 and 3.2 – 35.3 in the Bitou and Keurbooms tributaries respectively. A typical salt wedge salinity pattern is common in the Keurbooms tributary where saline water often intrudes underneath the freshwater, especially during high river flows. The following hypotheses were developed and tested in this study: The limited spatial distribution of S. maritima in the Keurbooms Estuary is due to limited availability of fine sediment habitat; and the source of the fine sediment in the estuary is the Bitou tributary rather than the Keurbooms tributary or the sea. It was further postulated that after sediment characteristics, floods are the major hydrological driver determining the distribution of S. maritima in the Keurbooms Estuary. The results of the surveys of the estuarine channel bottom sediments showed that the Keurbooms tributary was mostly characterized by the sand-size sediment fraction derived from the feldspathic and sandstone with evidence of fine sediment fractions restricted to the upper reaches at the confluence with Whiskey Creek. The Bitou was almost always composed of coarse sized sediments in the upper reaches, fine sediment deposits in the middle and lower reaches and medium sorted sand with almost no clay or calcium carbonate in the estuarine component below the confluence of the tributaries. These findings were further supported by the surface sediment deposited within the S. maritima intertidal salt marsh, which showed finer sediment deposits in the Bitou marsh compared to the Keurbooms marsh surface. Similar results were also found in the sediment cores, with the Keurbooms marsh sediment becoming finer with increasing depth whereas fine sediments reduced with depth in the Bitou marsh. The results of the sediment mineralogy indicated that the increased concentrations of clay minerals in the S. maritima surface sediments are derived from the Bokkeveld shale, siltstone and clay slate exposed above the N2 Bridge in the Keurbooms Estuary. GIS mapping shows that S. maritima has been declining over the past two decades, with rapid decreases especially evident after big flooding events. The GIS mapping also indicates that the patches of the S. maritima in the Keurbooms tributary are more exposed to big floods than the Bitou marsh. Despite showing an overall decline, S. maritima area coverage remained more consistent in the lower reaches of the Bitou tributary than in the Keurbooms tributary. Despite the larger and more persistent area cover, the S. maritima plants were shorter and less dense than the plants growing in the sandy substrate. The black/grey colouration of soil with increasing depth in the Bitou tributary was an indication of the reduced state of the soil caused by prolonged waterlogged conditions. The roots of S. maritima in both tributaries were mostly restricted to the sub-surface substrate layer (i.e. 0 – 0.25 m), although the Bitou populations showed more vegetative propagation than the Keurbooms populations. This mechanism of reproduction was also demonstrated during the transplant experiment which showed a greater number of new stem production in the fine sediment substrates compared to the sandy silt substrates. Although accretion rates were not determined in this study, the short-term sediment deposition rates revealed that sedimentation is active in the marshes of the Keurbooms Estuary. Therefore, in spite of showing a decline in area cover, the production of viable seed and observed vegetative propagation suggest that the S. maritima is likely to colonize open stable intertidal mudflats / sandflats, thus maintaining its distribution as an intertidal species in the salt marshes of the Keurbooms Estuary.
- Full Text:
- Date Issued: 2017
The interaction of selected bacteria with tailored electrospun fibres: towards future applications in bioremediation, bacterial inactivation and electricity generation
- Authors: Mfuku, Aphiwe
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65123 , vital:28693
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
- Authors: Mfuku, Aphiwe
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65123 , vital:28693
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
Microencapsulation of anti-tuberculosis drugs using sporopollenin
- Authors: Mhlana, Kanyisile
- Date: 2017
- Subjects: Mycobacterium tuberculosis -- South Africa -- Prevention Microencapsulation , Plant spores
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13912 , vital:27357
- Description: In this thesis, we explore the benefits of microencapsulating isoniazid and pyrazinamide within sporopollenin exine capsules derived from Lycopodium clavatum. Sporopollenin is a natural biopolymer, which is extracted from the outer shell of pollen grains. These hollow microcapsules can encapsulate and release drug actives in a controlled manner and possess many other advantages such as homogeneity in morphology and size, resilience to both strong acids and bases, they have antioxidant properties as well as UV protection to protect the material inside the microcapsule. Compared to artificial microcapsules, sporopollenin’s muco-adhesion to intestinal tissues contributes greatly to the extended contact of the sporopollenin with the intestines leading to an increased efficiency of delivery of drugs. The hollow microcapsules can be easily filled with a solution of the active or active in a liquid form by simply mixing both together. The drug actives are released in the human body depending on pH factors. Active release can otherwise have controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell so that high drug concentrations are delivered to the site of infection. Encapsulation of the drug active will possibly improve therapeutic abilities of the drugs; simplify the treatment of TB-HIV coinfections by eliminating troublesome drug-drug interactions and drastically reduce or eliminates side effects. The SECs were loaded using a passive filling method. The drug active (0.1 g) was dissolved in a solvent and mixed with the SECs (0.1 g) for 10 minutes. After mixing for 10 minutes, the solvent was removed by a rotary evaporator and dried to a constant mass. The surface of the sporopollenin exines were analysed on a FTIR to observe if there are any drug deposits on the surface of the SECs. The loading efficiency and drug release percentage was determined by using calibrations curves and analysed on a UV-vis spectrophotometer. Further work has been proposed in which to characterize the SECs further and producing coated tablets from loaded SECs.
- Full Text:
- Date Issued: 2017
- Authors: Mhlana, Kanyisile
- Date: 2017
- Subjects: Mycobacterium tuberculosis -- South Africa -- Prevention Microencapsulation , Plant spores
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13912 , vital:27357
- Description: In this thesis, we explore the benefits of microencapsulating isoniazid and pyrazinamide within sporopollenin exine capsules derived from Lycopodium clavatum. Sporopollenin is a natural biopolymer, which is extracted from the outer shell of pollen grains. These hollow microcapsules can encapsulate and release drug actives in a controlled manner and possess many other advantages such as homogeneity in morphology and size, resilience to both strong acids and bases, they have antioxidant properties as well as UV protection to protect the material inside the microcapsule. Compared to artificial microcapsules, sporopollenin’s muco-adhesion to intestinal tissues contributes greatly to the extended contact of the sporopollenin with the intestines leading to an increased efficiency of delivery of drugs. The hollow microcapsules can be easily filled with a solution of the active or active in a liquid form by simply mixing both together. The drug actives are released in the human body depending on pH factors. Active release can otherwise have controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell so that high drug concentrations are delivered to the site of infection. Encapsulation of the drug active will possibly improve therapeutic abilities of the drugs; simplify the treatment of TB-HIV coinfections by eliminating troublesome drug-drug interactions and drastically reduce or eliminates side effects. The SECs were loaded using a passive filling method. The drug active (0.1 g) was dissolved in a solvent and mixed with the SECs (0.1 g) for 10 minutes. After mixing for 10 minutes, the solvent was removed by a rotary evaporator and dried to a constant mass. The surface of the sporopollenin exines were analysed on a FTIR to observe if there are any drug deposits on the surface of the SECs. The loading efficiency and drug release percentage was determined by using calibrations curves and analysed on a UV-vis spectrophotometer. Further work has been proposed in which to characterize the SECs further and producing coated tablets from loaded SECs.
- Full Text:
- Date Issued: 2017
Molecular cloning and expression of equine CYP1A2 in Escherichia coli
- Authors: Mkabayi, Lithalethu
- Date: 2017
- Subjects: Escherichia coli , Escherichia coli infections in animals , Cytochrome P-450 , Cytochromes , Horses -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4830 , vital:20734
- Description: Information regarding drug metabolism in veterinary species, especially horses, remains fragmented and incomplete. This information is essential for detection of metabolites of potential performance-enhancing substances in horseracing and for veterinary drug development. Equine liver microsomes have been used to study metabolism of a limited number of drugs, but these provide little information about individual drug metabolizing enzymes. Recombinant CYP enzyme systems are commonly used to determine contribution of individual CYP to metabolism of specific drugs. A limited number of recombinant equine CYPs have been expressed in insect cells and mammalian cell lines. However, there are no reports of recombinant equine CYP1A2 enzyme. In this study, equine CYP1A2 was identified, codon-optimized, cloned and expressed in E. coli BL21 cells. Multiple sequence alignments of equine CYP1A2 revealed an amino acid sequence identity of 83.69% to its human homolog which has previously been expressed in E. coli. The enzyme was expressed using both auto-induction and IPTG induction. Expressed equine CYP1A2 had a size of about 55 kDa, and was insoluble after cell lysis. Sarkosyl- solubilized CYP1A2 was purified using nickel affinity chromatography and gel filtration. For activity reconstitution, yeast NADPH-cytochrome P450 reductase was first expressed in E. coli BL21 cells and exhibited activity of 0.13 U/ml. Activity assay with Glo-P450 CYP1A2 assay kit indicated that CYP1A2 was inactive. Despite numerous attempts to obtain the activity, the CYP1A2 remained inactive. Although expression of equine CYP1A2 in E. coli produced non- catalytically active enzyme, this study could be used as the first step in an effort to fully develop a recombinant equine CYP1A2 system.
- Full Text:
- Date Issued: 2017
- Authors: Mkabayi, Lithalethu
- Date: 2017
- Subjects: Escherichia coli , Escherichia coli infections in animals , Cytochrome P-450 , Cytochromes , Horses -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4830 , vital:20734
- Description: Information regarding drug metabolism in veterinary species, especially horses, remains fragmented and incomplete. This information is essential for detection of metabolites of potential performance-enhancing substances in horseracing and for veterinary drug development. Equine liver microsomes have been used to study metabolism of a limited number of drugs, but these provide little information about individual drug metabolizing enzymes. Recombinant CYP enzyme systems are commonly used to determine contribution of individual CYP to metabolism of specific drugs. A limited number of recombinant equine CYPs have been expressed in insect cells and mammalian cell lines. However, there are no reports of recombinant equine CYP1A2 enzyme. In this study, equine CYP1A2 was identified, codon-optimized, cloned and expressed in E. coli BL21 cells. Multiple sequence alignments of equine CYP1A2 revealed an amino acid sequence identity of 83.69% to its human homolog which has previously been expressed in E. coli. The enzyme was expressed using both auto-induction and IPTG induction. Expressed equine CYP1A2 had a size of about 55 kDa, and was insoluble after cell lysis. Sarkosyl- solubilized CYP1A2 was purified using nickel affinity chromatography and gel filtration. For activity reconstitution, yeast NADPH-cytochrome P450 reductase was first expressed in E. coli BL21 cells and exhibited activity of 0.13 U/ml. Activity assay with Glo-P450 CYP1A2 assay kit indicated that CYP1A2 was inactive. Despite numerous attempts to obtain the activity, the CYP1A2 remained inactive. Although expression of equine CYP1A2 in E. coli produced non- catalytically active enzyme, this study could be used as the first step in an effort to fully develop a recombinant equine CYP1A2 system.
- Full Text:
- Date Issued: 2017
Evaluation of some pseudomonas species isolated from Hogsback forest reserve for the production of antibacterial compounds
- Authors: Mkono, Yonela Pelokazi
- Date: 2017
- Subjects: Bacteriology -- South Africa -- Eastern Cape Pseudomonas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5961 , vital:29458
- Description: Pseudomonas species are Gram-negative bacteria most abundant in soil and water bodies, with the capacity to thrive in varied environments. They are largely associated with resistant pathogenic bacteria linked to human and plant diseases. Species such as Pseudomonas aeruginosa have been particularly targeted as case studies due to the extremity to which they pose a threat to human health. With more focus directed at using these species for biocontrol and bioremediation purposes, their role in bioactive compound production may be equally important. As the crisis on antimicrobial resistance still persists, the need for effective antimicrobial compounds is ever more urgent and solutions may possibly still be dormant in bacterial species whose potential has not been fully investigated. On a bid to source out potential antimicrobial compound producers, soil samples were collected from Hogback forest reserve in the province of the Eastern Cape, South Africa. For bacterial screening, M1 and R2A agar were used and the cultures grown at 37˚C for a period of seven days. After the presumed Pseudomonas species were identified, antimicrobial production was determined by submerged fermentation method using nutrient broth as media of choice. Active isolates were further studied to determine the optimum conditions which best facilitate for antimicrobial compound production, with parameters such as temperature (25˚C – 40˚C) and pH (4 – 9) considered. The role plasmids play in antimicrobial compound production was also investigated. Each isolate was grown in fermentation media containing Sodium dodecyl sulphate and Ethedium Bromide, at varying concentrations, to facilitate for plasmid curing. With each sample, distinct colonies were identified with varying pigmentations most dominant being a cream colour. The identity of the isolated strains was achieved through sequencing of 16S rDNA. Phylogenetic analysis showed that isolate A16 had 80 percent homology with Pseudomonas plecoglossicida strain P4 and share a close ancestor with isolates Y52 and Y81, also isolate Y89 showed a 90 percent homology with Pseudomonas sp. Co-11a. With the exception of isolate A16, the isolates which were active against Gram-negative bacteria lost activity as the screening processes continued. When looking at temperature variations, isolates Y81 and A16 were highly active with maximum activity observed at 35˚C while Y89 performed best at 25˚C and Y52 showed constant activity across all studied temperatures. The plasmids in all isolates were found to be 48.5 kb in size with the exception of isolate Y89 which was 20 kb. The plasmids were cured at concentrations of (1 mg/ml; 5 mg/ml; 7 mg/ml; 10 mg/ml; 11 mg/ml) SDS and (125 μg/ml; 6.5 μg/ml; 5μg/ml) EtBr. The curing process also showed changes in both the antimicrobial activity of the isolates as well as their physical characteristics. The isolates are the first reported Pseudomonas species from Hogsback forest reserve with the ability to produce antimicrobial compounds which are active against Gram-positive and Gram-negative bacteria. These mesophilic bacteria also show that plasmids do not pay any role in the production of antimicrobial compounds and that the biosynthesis genes are highly likely to be chromosomal borne meaning that the production cannot be linked to horizontal transfer of genes. Therefore, these isolated Pseudomonas species provide a potential reservoir of antimicrobial compounds which may play an important role in the antimicrobial resistance phenomenon.
- Full Text:
- Date Issued: 2017
- Authors: Mkono, Yonela Pelokazi
- Date: 2017
- Subjects: Bacteriology -- South Africa -- Eastern Cape Pseudomonas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5961 , vital:29458
- Description: Pseudomonas species are Gram-negative bacteria most abundant in soil and water bodies, with the capacity to thrive in varied environments. They are largely associated with resistant pathogenic bacteria linked to human and plant diseases. Species such as Pseudomonas aeruginosa have been particularly targeted as case studies due to the extremity to which they pose a threat to human health. With more focus directed at using these species for biocontrol and bioremediation purposes, their role in bioactive compound production may be equally important. As the crisis on antimicrobial resistance still persists, the need for effective antimicrobial compounds is ever more urgent and solutions may possibly still be dormant in bacterial species whose potential has not been fully investigated. On a bid to source out potential antimicrobial compound producers, soil samples were collected from Hogback forest reserve in the province of the Eastern Cape, South Africa. For bacterial screening, M1 and R2A agar were used and the cultures grown at 37˚C for a period of seven days. After the presumed Pseudomonas species were identified, antimicrobial production was determined by submerged fermentation method using nutrient broth as media of choice. Active isolates were further studied to determine the optimum conditions which best facilitate for antimicrobial compound production, with parameters such as temperature (25˚C – 40˚C) and pH (4 – 9) considered. The role plasmids play in antimicrobial compound production was also investigated. Each isolate was grown in fermentation media containing Sodium dodecyl sulphate and Ethedium Bromide, at varying concentrations, to facilitate for plasmid curing. With each sample, distinct colonies were identified with varying pigmentations most dominant being a cream colour. The identity of the isolated strains was achieved through sequencing of 16S rDNA. Phylogenetic analysis showed that isolate A16 had 80 percent homology with Pseudomonas plecoglossicida strain P4 and share a close ancestor with isolates Y52 and Y81, also isolate Y89 showed a 90 percent homology with Pseudomonas sp. Co-11a. With the exception of isolate A16, the isolates which were active against Gram-negative bacteria lost activity as the screening processes continued. When looking at temperature variations, isolates Y81 and A16 were highly active with maximum activity observed at 35˚C while Y89 performed best at 25˚C and Y52 showed constant activity across all studied temperatures. The plasmids in all isolates were found to be 48.5 kb in size with the exception of isolate Y89 which was 20 kb. The plasmids were cured at concentrations of (1 mg/ml; 5 mg/ml; 7 mg/ml; 10 mg/ml; 11 mg/ml) SDS and (125 μg/ml; 6.5 μg/ml; 5μg/ml) EtBr. The curing process also showed changes in both the antimicrobial activity of the isolates as well as their physical characteristics. The isolates are the first reported Pseudomonas species from Hogsback forest reserve with the ability to produce antimicrobial compounds which are active against Gram-positive and Gram-negative bacteria. These mesophilic bacteria also show that plasmids do not pay any role in the production of antimicrobial compounds and that the biosynthesis genes are highly likely to be chromosomal borne meaning that the production cannot be linked to horizontal transfer of genes. Therefore, these isolated Pseudomonas species provide a potential reservoir of antimicrobial compounds which may play an important role in the antimicrobial resistance phenomenon.
- Full Text:
- Date Issued: 2017
Statistical modelling applied to perceptions of fraud
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics , Mathematical models Bank fraud Banks and banking -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41073 , vital:36289
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics , Mathematical models Bank fraud Banks and banking -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41073 , vital:36289
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
Statistical modelling applied to perceptions of fraud
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41064 , vital:36288
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41064 , vital:36288
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
Interactions between two biological control agents released on Pereskia aculeata Miller (Cactaceae), in South Africa
- Authors: Mnqeta, Zezethu
- Date: 2017
- Subjects: Pereskia aculeata -- Biological control , Cactus -- Biological control -- South Africa , Alien plants -- Biological control -- South Africa , Flea beetles -- South Africa , Coreidae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7949 , vital:21327
- Description: Pereskia aculeata Miller (Cactaceae) is an alien invasive plant introduced into South Africa from Brazil, which has negative impacts on native biodiversity in South Africa. Phenrica guerini Bechyne (Chrysomelidae) and Catorhintha schaffneri Brailovsky & Garcia (Coreidae) are two biological control agents released against P. aculeata in South Africa. Phenrica guerini was first released against P. aculeata, in 1991, followed by C. schaffneri in 2014. The overall aim of this study was to improve the biological control programme against P. aculeata in order to decrease its density to a level where it does not threaten the native biodiversity of South Africa. The first part of this study evaluated the efficacy of P. guerini on P. aculeata at Port Alfred (Eastern Cape) to better understand the role of P. guerini in the biological control of P. aculeata. An insecticide exclusion experiment was conducted over 100 days. Plots with P. guerini had a mean of 187 (SE ± 62) fewer leaves/m2 than plots without P. guerini. The agent reduced percentage cover in plots with P. guerini, with a mean of 19.42% (SE ± 3.15) lower cover than plots without P. guerini. Although P. guerini had an impact on P. aculeata at Port Alfred previous studies have indicated that a reduction to below 50% cover is required for native biodiversity to recover and the agent only reduced cover to 62% at Port Alfred. Phenrica guerini has therefore not reduced percentage cover sufficiently to completely control the weed. The data collected from Port Alfred was compared to the performance of the agent nationwide. Although P. guerini was found at far more sites than previously recorded, there were very few sites with comparable levels of damage to Port Alfred. This evidence suggests that P. guerini is not sufficiently damaging to reduce P. aculeata to acceptable levels and other biological control agents should be considered.Interactions between two biological control agents can have complex and unexpected impacts for a biological control programme. The second part of this study was to investigate interactions between C. schaffneri and P. guerini under laboratory conditions to test whether the two agents, individually or jointly, enhanced or reduced their impact on P. aculeata. Potted P. aculeata plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species in combination. Four stocking densities, ranging from 2 to 12 insects per plant were used. Catorhintha schaffneri alone at high densities was more damaging than all other treatments with a significantly greater reduction in the mean number of leaves, 11.7 (SE ± 1.29), and shoot lengths, 2.17cm (SE ± O. 75). Even at lower density treatments, the combination of the two agents was not significantly more damaging than C. schaffneri alone and C. schaffneri was always more damaging than P. guerini alone. Mortality of P. guerini was significantly higher than C. schaffneri at the highest stocking density when in combination. Phenrica guerini contributes towards the biological control of P. aculeata at some sites in South Africa but not enough to completely control the weed. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. Catorhintha schaffneri should be released at sites were P. guerini is not present and evaluations of the success of this agent in the field should be conducted. Extrapolation of laboratory-based studies into the field is often challenging so mass-rearing of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2017
- Authors: Mnqeta, Zezethu
- Date: 2017
- Subjects: Pereskia aculeata -- Biological control , Cactus -- Biological control -- South Africa , Alien plants -- Biological control -- South Africa , Flea beetles -- South Africa , Coreidae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7949 , vital:21327
- Description: Pereskia aculeata Miller (Cactaceae) is an alien invasive plant introduced into South Africa from Brazil, which has negative impacts on native biodiversity in South Africa. Phenrica guerini Bechyne (Chrysomelidae) and Catorhintha schaffneri Brailovsky & Garcia (Coreidae) are two biological control agents released against P. aculeata in South Africa. Phenrica guerini was first released against P. aculeata, in 1991, followed by C. schaffneri in 2014. The overall aim of this study was to improve the biological control programme against P. aculeata in order to decrease its density to a level where it does not threaten the native biodiversity of South Africa. The first part of this study evaluated the efficacy of P. guerini on P. aculeata at Port Alfred (Eastern Cape) to better understand the role of P. guerini in the biological control of P. aculeata. An insecticide exclusion experiment was conducted over 100 days. Plots with P. guerini had a mean of 187 (SE ± 62) fewer leaves/m2 than plots without P. guerini. The agent reduced percentage cover in plots with P. guerini, with a mean of 19.42% (SE ± 3.15) lower cover than plots without P. guerini. Although P. guerini had an impact on P. aculeata at Port Alfred previous studies have indicated that a reduction to below 50% cover is required for native biodiversity to recover and the agent only reduced cover to 62% at Port Alfred. Phenrica guerini has therefore not reduced percentage cover sufficiently to completely control the weed. The data collected from Port Alfred was compared to the performance of the agent nationwide. Although P. guerini was found at far more sites than previously recorded, there were very few sites with comparable levels of damage to Port Alfred. This evidence suggests that P. guerini is not sufficiently damaging to reduce P. aculeata to acceptable levels and other biological control agents should be considered.Interactions between two biological control agents can have complex and unexpected impacts for a biological control programme. The second part of this study was to investigate interactions between C. schaffneri and P. guerini under laboratory conditions to test whether the two agents, individually or jointly, enhanced or reduced their impact on P. aculeata. Potted P. aculeata plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species in combination. Four stocking densities, ranging from 2 to 12 insects per plant were used. Catorhintha schaffneri alone at high densities was more damaging than all other treatments with a significantly greater reduction in the mean number of leaves, 11.7 (SE ± 1.29), and shoot lengths, 2.17cm (SE ± O. 75). Even at lower density treatments, the combination of the two agents was not significantly more damaging than C. schaffneri alone and C. schaffneri was always more damaging than P. guerini alone. Mortality of P. guerini was significantly higher than C. schaffneri at the highest stocking density when in combination. Phenrica guerini contributes towards the biological control of P. aculeata at some sites in South Africa but not enough to completely control the weed. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. Catorhintha schaffneri should be released at sites were P. guerini is not present and evaluations of the success of this agent in the field should be conducted. Extrapolation of laboratory-based studies into the field is often challenging so mass-rearing of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.
- Full Text:
- Date Issued: 2017
Treatment of anaerobically digested brewery effluent in high rate algal ponds: an understanding of the microbial community structure in the ponds and the underlying mechanisms responsible for nutrient removal from the effluent
- Authors: Mogane, Mmathabo Lucretia
- Date: 2017
- Subjects: Brewing industry -- Waste disposal -- South Africa , Breweries -- Waste displosal -- South Africa , Algae culture -- South Africa , Water -- Purification -- South Africa , Sewage lagoons -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5026 , vital:20754
- Full Text:
- Date Issued: 2017
- Authors: Mogane, Mmathabo Lucretia
- Date: 2017
- Subjects: Brewing industry -- Waste disposal -- South Africa , Breweries -- Waste displosal -- South Africa , Algae culture -- South Africa , Water -- Purification -- South Africa , Sewage lagoons -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5026 , vital:20754
- Full Text:
- Date Issued: 2017
Geological and geophysical investigations of the reservoir rock properties of the Gamtoos Basin in the Eastern Cape Province of South Africa
- Authors: Mokoele, Salmina Phuthi
- Date: 2017
- Subjects: Petroleum reserves -- Mechanical properties Petroleum reserves -- South Africa -- Eastern Cape Geophysics -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7863 , vital:30779
- Description: Geological and geophysical studies of the Gamtoos Basin were carried out by using the research methods of stratigraphic analysis, petrographic analysis, sedimentary facies analysis, and geophysical studies. The orientation of the Gamtoos Basin onshore is controlled by the Gamtoos Fault which cuts through the lithologies of the Cape Supergroup on the eastern edge of the basin. Magnetic data and depth slices show the presence of the Cape Supergroup basement on the south east corner of the onshore Kirkwood Formation which is further sitting on the Gamtoos Group basement from the Neoproterozoic extending up to 8860 m in depth. Most previously compiled stratigraphic profiles of the Uitanhage Group revealed the presence of reddish massive conglomerate units from the Enon Formation and massive reddish to greenish alternating units of sandstones, siltstones and mudstones from the Kirkwood Formation. The results obtained from this research also revealed the presence of reddish to whitish massive alternating units of sandstones, mudstones and siltstones from the upper Enon Formation overlaying the reddish massive conglomeritic layers while the alternating reddish to greenish units of sandstones, siltstones and mudstones from the Kirkwood Formation are overlaid by massive reddish to greyish conglomeritic layers. Thirteen types of lithofacies and five types of biofacies were accounted for across the Gamtoos Basin from core logs, field observations and petrographic analysis. The same type of reddish to greyish massive conglomerate facies interbedded with subordinate sandstone lenses were observed on both the Enon (Lower most part) and the Kirkwood (top most part) Formations. Similar reddish to whitish sandstone facies were also observed in both formations except some of the units from the Kirkwood Formation revealed the presence of a lot of sedimentary structures such as laminations, thin beds, tabular cross beds, trough cross beds, convolute structures, load casts and even secondary structures like calcite veins and honey comb structures. Mudstone deposits are divided into reddish laminated facies and whitish massive facies. The whitish mudstone facies of the Enon Formation comprise caliche indicating the process of leaching while the reddish facies contain mudcracks indicating the process of desiccation. The Kirkwood Formation comprises reddish laminated mudstone facies and whitish massive mudstones. Petrographic studies revealed the presence of quartz arenites, lithic arenites, quartz wacke, lithic wacke, pelletic wacke, siltstones and mudstones. The mineral compositions were monocrystalline and polycrystalline quartz, plagioclase, K-feldspar and lithic fragments as the main framework grains. Muscovite and glauconite were identified as accessory minerals along with heavy minerals of hematite spotted on a few occasions. The matrix was composed of clay (mainly kaolinite and smectite), bentonite, illite-sericite and fine quartz silts. Microscope petrography revealed that organic matters occurred in 4 occurrences, i.e. as organic intraclasts, kerogen pellets, organic carbon laminae or stringers, and diagenetic crack-filling organic carbon (asphalt). Density determinations onshore have revealed an average wet density of 2.439 g/cm3 for the Enon Formation sandstones and 2.589 g/cm3 for the Kirkwood Formation sandstones. The average rock density for Borehole Ha-B2 is 2.67 g/cm3 whereas Borehole Ha-G1 rocks show an average density of 2.64 g/cm3. Geophysical data from the offshore boreholes has indicated an increase in the following parameters with depth: bulk density, porosity and geothermal gradient. Data from borehole logs resulted in a linear relationship between bulk density and depth although some boreholes were represented by more than one linear segment in one graph still showing gradual increase of bulk density with depth. The basin was deposited in terrestrial environments (braided fluvial fans and meandering rivers) and marine environments (beach, shallow and deep marine).
- Full Text:
- Date Issued: 2017
- Authors: Mokoele, Salmina Phuthi
- Date: 2017
- Subjects: Petroleum reserves -- Mechanical properties Petroleum reserves -- South Africa -- Eastern Cape Geophysics -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/7863 , vital:30779
- Description: Geological and geophysical studies of the Gamtoos Basin were carried out by using the research methods of stratigraphic analysis, petrographic analysis, sedimentary facies analysis, and geophysical studies. The orientation of the Gamtoos Basin onshore is controlled by the Gamtoos Fault which cuts through the lithologies of the Cape Supergroup on the eastern edge of the basin. Magnetic data and depth slices show the presence of the Cape Supergroup basement on the south east corner of the onshore Kirkwood Formation which is further sitting on the Gamtoos Group basement from the Neoproterozoic extending up to 8860 m in depth. Most previously compiled stratigraphic profiles of the Uitanhage Group revealed the presence of reddish massive conglomerate units from the Enon Formation and massive reddish to greenish alternating units of sandstones, siltstones and mudstones from the Kirkwood Formation. The results obtained from this research also revealed the presence of reddish to whitish massive alternating units of sandstones, mudstones and siltstones from the upper Enon Formation overlaying the reddish massive conglomeritic layers while the alternating reddish to greenish units of sandstones, siltstones and mudstones from the Kirkwood Formation are overlaid by massive reddish to greyish conglomeritic layers. Thirteen types of lithofacies and five types of biofacies were accounted for across the Gamtoos Basin from core logs, field observations and petrographic analysis. The same type of reddish to greyish massive conglomerate facies interbedded with subordinate sandstone lenses were observed on both the Enon (Lower most part) and the Kirkwood (top most part) Formations. Similar reddish to whitish sandstone facies were also observed in both formations except some of the units from the Kirkwood Formation revealed the presence of a lot of sedimentary structures such as laminations, thin beds, tabular cross beds, trough cross beds, convolute structures, load casts and even secondary structures like calcite veins and honey comb structures. Mudstone deposits are divided into reddish laminated facies and whitish massive facies. The whitish mudstone facies of the Enon Formation comprise caliche indicating the process of leaching while the reddish facies contain mudcracks indicating the process of desiccation. The Kirkwood Formation comprises reddish laminated mudstone facies and whitish massive mudstones. Petrographic studies revealed the presence of quartz arenites, lithic arenites, quartz wacke, lithic wacke, pelletic wacke, siltstones and mudstones. The mineral compositions were monocrystalline and polycrystalline quartz, plagioclase, K-feldspar and lithic fragments as the main framework grains. Muscovite and glauconite were identified as accessory minerals along with heavy minerals of hematite spotted on a few occasions. The matrix was composed of clay (mainly kaolinite and smectite), bentonite, illite-sericite and fine quartz silts. Microscope petrography revealed that organic matters occurred in 4 occurrences, i.e. as organic intraclasts, kerogen pellets, organic carbon laminae or stringers, and diagenetic crack-filling organic carbon (asphalt). Density determinations onshore have revealed an average wet density of 2.439 g/cm3 for the Enon Formation sandstones and 2.589 g/cm3 for the Kirkwood Formation sandstones. The average rock density for Borehole Ha-B2 is 2.67 g/cm3 whereas Borehole Ha-G1 rocks show an average density of 2.64 g/cm3. Geophysical data from the offshore boreholes has indicated an increase in the following parameters with depth: bulk density, porosity and geothermal gradient. Data from borehole logs resulted in a linear relationship between bulk density and depth although some boreholes were represented by more than one linear segment in one graph still showing gradual increase of bulk density with depth. The basin was deposited in terrestrial environments (braided fluvial fans and meandering rivers) and marine environments (beach, shallow and deep marine).
- Full Text:
- Date Issued: 2017
Foraging behaviour and thermal physiology of Cape sugarbirds: sex-specific responses to temperature
- Authors: Molepo, Mokgatla Jerry
- Date: 2017
- Subjects: Sexual dimorphism (Animals) , Sex differences Birds -- Behavior
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19124 , vital:28775
- Description: Body size (Mb) determines an animal’s energy and water demands for thermoregulation. Sexual dimorphism in Mb is common across many species, but its physiological consequences (e.g. energy and water demands) remain poorly understood. In this study, I determined if the sexually dimorphic Cape Sugarbird (Promerops cafer)–males are up to 15% larger than females, show sex-specific foraging patterns and physiological responses. To determine intraspecific variability behavioural in response to temperature, I compared flower visitation rates between male and female Cape Sugarbirds at different times of the day, and among days that varied in maximum air temperature. A total of 1207 males and 561 females were observed. Female Cape Sugarbirds visited flowers more often and continued to feed especially on hot days. Males generally dominated flower resources throughout the day, except on hot days. I also compared physiological responses in EWL, RMR and Tb between males and females at high air temperatures. There were no significant differences between the two sexes. Aggression which was overlooked appeared to have a high influence on foraging behaviour of Cape Sugarbirds. These results suggest that female Cape Sugarbirds will be more prone to energy and water stress during hot and dry summers in the Fynbos region because of resource dominance by male Cape Sugarbirds. Endemic birds, such as the Cape Sugarbird, warrant a conservation priority, especially since they are the dominant pollinator of the Protea plants in the Fynbos biome. The findings of this study will provide insights into population persistence of Cape Sugarbirds in response to predicted heat waves and rise in global temperatures.
- Full Text:
- Date Issued: 2017
- Authors: Molepo, Mokgatla Jerry
- Date: 2017
- Subjects: Sexual dimorphism (Animals) , Sex differences Birds -- Behavior
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19124 , vital:28775
- Description: Body size (Mb) determines an animal’s energy and water demands for thermoregulation. Sexual dimorphism in Mb is common across many species, but its physiological consequences (e.g. energy and water demands) remain poorly understood. In this study, I determined if the sexually dimorphic Cape Sugarbird (Promerops cafer)–males are up to 15% larger than females, show sex-specific foraging patterns and physiological responses. To determine intraspecific variability behavioural in response to temperature, I compared flower visitation rates between male and female Cape Sugarbirds at different times of the day, and among days that varied in maximum air temperature. A total of 1207 males and 561 females were observed. Female Cape Sugarbirds visited flowers more often and continued to feed especially on hot days. Males generally dominated flower resources throughout the day, except on hot days. I also compared physiological responses in EWL, RMR and Tb between males and females at high air temperatures. There were no significant differences between the two sexes. Aggression which was overlooked appeared to have a high influence on foraging behaviour of Cape Sugarbirds. These results suggest that female Cape Sugarbirds will be more prone to energy and water stress during hot and dry summers in the Fynbos region because of resource dominance by male Cape Sugarbirds. Endemic birds, such as the Cape Sugarbird, warrant a conservation priority, especially since they are the dominant pollinator of the Protea plants in the Fynbos biome. The findings of this study will provide insights into population persistence of Cape Sugarbirds in response to predicted heat waves and rise in global temperatures.
- Full Text:
- Date Issued: 2017