The relationship between financial sector deepening and income inequality in South Africa
- Authors: Mandleni, Siyanda
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462790 , vital:76335
- Description: This research analyzes the relationship between financial sector deepening and income inequality in South Africa from 1980 to 2019, using data from the World Bank Database and the Standardized World Income Inequality Database. An autoregressive distributed lag (ARDL) model is used to explore both the long- and short-run relationships that exist between these variables. Additionally, control variables like GDP, inflation, and structural changes that occurred, which include 1994 and 2005 are considered. According to the findings, the financial sector exacerbates income inequality in the long run. These findings highlight the need for policymakers to prioritize inclusive financial sector reforms. One recommendation is to enhance the access of Small, Medium, and Micro Enterprises (SMMEs) to formal financial services. For example, promoting more black industrialists and SMMEs in the supply of financial products and services. Possible reforms may include adjusting credit requirements for different income groups or offering lower interest rates on loans for businesses. Ensuring that more financial sector gains are retained within black communities can foster inclusive growth by generating jobs and ensuring a more equitable distribution of income. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mandleni, Siyanda
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462790 , vital:76335
- Description: This research analyzes the relationship between financial sector deepening and income inequality in South Africa from 1980 to 2019, using data from the World Bank Database and the Standardized World Income Inequality Database. An autoregressive distributed lag (ARDL) model is used to explore both the long- and short-run relationships that exist between these variables. Additionally, control variables like GDP, inflation, and structural changes that occurred, which include 1994 and 2005 are considered. According to the findings, the financial sector exacerbates income inequality in the long run. These findings highlight the need for policymakers to prioritize inclusive financial sector reforms. One recommendation is to enhance the access of Small, Medium, and Micro Enterprises (SMMEs) to formal financial services. For example, promoting more black industrialists and SMMEs in the supply of financial products and services. Possible reforms may include adjusting credit requirements for different income groups or offering lower interest rates on loans for businesses. Ensuring that more financial sector gains are retained within black communities can foster inclusive growth by generating jobs and ensuring a more equitable distribution of income. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
Comparison of the metabolic physiology of exploited and unexploited populations of red roman (Chrysoblephus laticeps) along the south coast of South Africa
- Authors: Nabani, Xolani Prince
- Date: 2023-10-13
- Subjects: Chrysoblephus laticeps , Marine fishes Climatic factors South Africa , Marine fishes Physiology South Africa , Marine fishes Metabolism , Respirometry , Marine protected area , Evolutionary impact of fishing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424358 , vital:72146
- Description: Anthropogenic-induced climate change and exploitation pose threat to many marine fishes on which a vast majority of people around the world depend. Rapid changes in sea surface temperature have a direct impact on the physiology of ectothermic organisms such as fish, potentially resulting in changes to population distribution, abundance, and demographics. In the face of climate change, the impacts of increasing temperature variability on fish populations may be exacerbated by exploitation. Understanding how the resilience of exploited populations is affected by climate change is critical to predict how fishes will respond in the future. This study aimed to augment our knowledge on the impact of exploitation and thermal variability on fishes by comparing the thermal physiology of an exploited and unexploited population of the resident, reef-dwelling, Chrysoblephus laticeps. Twenty live fish were collected from the exploited, Cape St Francis and 18 fish from the unexploited, Goukamma Marine Protected Area and transported to the laboratory. The metabolic performance, in terms of standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS) of individual C. laticeps were estimated repeatedly at 10 ℃, 16 °C and 21 °C. Linear mixed effects models were used to examine the relationship between temperature, population, and metabolic rate and a ‘cvequality’ test analysis was used to compare the variance structure of the metabolic rate regression model for each population. Overall, the findings of this study show that Chrysoblephus laticeps from the unexploited population maintains a significantly higher aerobic scope (AS) across all temperature treatments (10, 16 and 21 ℃) when compared with those from the exploited population. In addition, the maximum metabolic rate (MMR) of individuals from the unexploited population was significantly higher than that of individuals from the exploited population, but there was no evidence to suggest that variability was significantly different between the populations. On the other hand, the individuals from an exploited population had a significantly higher standard metabolic rate (SMR) at high temperatures of 21 ℃, while the unexploited population had a low SMR at these high temperatures, but a high SMR at 10 ℃. Despite these differences there was no significant variation in the SMR between the two populations. The findings of this study confirm previous work on different exploited and unexploited populations of C. laticeps and together these findings suggest that hook and line exploitation lead to reduced physiological phenotypic diversity and reduced physiological performance in exploited fish populations. These findings emphasise the importance of incorporating the iii physiological information to develop viable fisheries management tools in the context of climate change. This study also highlights the effectiveness of MPAs in conserving highperformance physiological phenotypes to maintain phenotypic diversity in fish populations. Future research should aim to evaluate the efficacy of existing MPAs in preserving the physiological diversity of important hook and line fisheries species, while fisheries managers should consider augmenting their approaches through the incorporation of well-designed MPA’s to promote physiological diversity. This will be critical to advance the development of sustainable management practices, not only in a South African context but globally, where oceanic and coastal environmental conditions are expected to rapidly change in the future. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Nabani, Xolani Prince
- Date: 2023-10-13
- Subjects: Chrysoblephus laticeps , Marine fishes Climatic factors South Africa , Marine fishes Physiology South Africa , Marine fishes Metabolism , Respirometry , Marine protected area , Evolutionary impact of fishing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424358 , vital:72146
- Description: Anthropogenic-induced climate change and exploitation pose threat to many marine fishes on which a vast majority of people around the world depend. Rapid changes in sea surface temperature have a direct impact on the physiology of ectothermic organisms such as fish, potentially resulting in changes to population distribution, abundance, and demographics. In the face of climate change, the impacts of increasing temperature variability on fish populations may be exacerbated by exploitation. Understanding how the resilience of exploited populations is affected by climate change is critical to predict how fishes will respond in the future. This study aimed to augment our knowledge on the impact of exploitation and thermal variability on fishes by comparing the thermal physiology of an exploited and unexploited population of the resident, reef-dwelling, Chrysoblephus laticeps. Twenty live fish were collected from the exploited, Cape St Francis and 18 fish from the unexploited, Goukamma Marine Protected Area and transported to the laboratory. The metabolic performance, in terms of standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS) of individual C. laticeps were estimated repeatedly at 10 ℃, 16 °C and 21 °C. Linear mixed effects models were used to examine the relationship between temperature, population, and metabolic rate and a ‘cvequality’ test analysis was used to compare the variance structure of the metabolic rate regression model for each population. Overall, the findings of this study show that Chrysoblephus laticeps from the unexploited population maintains a significantly higher aerobic scope (AS) across all temperature treatments (10, 16 and 21 ℃) when compared with those from the exploited population. In addition, the maximum metabolic rate (MMR) of individuals from the unexploited population was significantly higher than that of individuals from the exploited population, but there was no evidence to suggest that variability was significantly different between the populations. On the other hand, the individuals from an exploited population had a significantly higher standard metabolic rate (SMR) at high temperatures of 21 ℃, while the unexploited population had a low SMR at these high temperatures, but a high SMR at 10 ℃. Despite these differences there was no significant variation in the SMR between the two populations. The findings of this study confirm previous work on different exploited and unexploited populations of C. laticeps and together these findings suggest that hook and line exploitation lead to reduced physiological phenotypic diversity and reduced physiological performance in exploited fish populations. These findings emphasise the importance of incorporating the iii physiological information to develop viable fisheries management tools in the context of climate change. This study also highlights the effectiveness of MPAs in conserving highperformance physiological phenotypes to maintain phenotypic diversity in fish populations. Future research should aim to evaluate the efficacy of existing MPAs in preserving the physiological diversity of important hook and line fisheries species, while fisheries managers should consider augmenting their approaches through the incorporation of well-designed MPA’s to promote physiological diversity. This will be critical to advance the development of sustainable management practices, not only in a South African context but globally, where oceanic and coastal environmental conditions are expected to rapidly change in the future. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
The effects of short-duration overnight kraaling on herbaceous vegetation and soils in mesic grassland
- Authors: Mgwali, Nompendulo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424721 , vital:72178
- Description: Land degradation is widespread in communal rangelands in the grassland biome of South Africa, and often attributed to overstocking and lack of coordinated management. Excessive pressure on the herbaceous component has contributed to the uncontrolled spread of opportunistic invasive alien woody species e.g. Acacia mearnsii in many degraded areas, resulting in significant loss of ecosystem service capacity, along with soil and land productivity. Short-duration overnight kraaling has been suggested as a tool for restoring degraded rangelands. Recent studies in semi-arid savannas and shrublands have reported increased grass cover, soil nutrients and palatability and concluded that short-duration kraaling is a low-cost and effective way of restoring degraded rangelands using livestock. However, the response of different plant functional types and communities to such intense livestock impact may vary depending on local context. This study used twelve paired kraal and control sites to investigate the effects of short-duration (7-24 days) overnight kraaling of livestock on herbaceous vegetation and soils in a mesic grassland. The study area is generally considered to be overgrazed but has considerable variation in grass composition and basal cover. Sites included relatively intact natural grassland and sites where wattle infestations had been cleared and where mostly bare ground remained. I tested the hypotheses that overnight kraaling would result in (1) increased basal cover due to introduction of grass seed and stimulation of germination through hoof action, (2) increased infiltration due to hoof action, and (3) increased soil nutrients and organic matter due to dung and urine deposition. I also hypothesized that factors such as a site’s initial grass cover, its slope, the occurrence and amount of rainfall before and during kraaling, and the kraaling intensity (number of livestock and duration of the kraaling event) would influence the magnitude and direction of the kraaling effect. The effect of kraaling on vegetation was strongly dependent on initial condition. Kraaling increased basal cover of grasses when sites had low initial basal cover, but decreased basal cover if initial values were over 50%. Infiltration increased if kraaling took place during or after rain but decreased if kraaling took place when soils were dry. Kraaling increased soil P and K. In mesic grasslands, short-duration overnight kraaling is promising as a tool for rehabilitating degraded sites but should be avoided where the grass sward is relatively intact. I recommend that the suitability of kraaling be further evaluated per vegetation type and local context. , Thesis (MSc) -- Faculty of Science, Botany, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mgwali, Nompendulo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424721 , vital:72178
- Description: Land degradation is widespread in communal rangelands in the grassland biome of South Africa, and often attributed to overstocking and lack of coordinated management. Excessive pressure on the herbaceous component has contributed to the uncontrolled spread of opportunistic invasive alien woody species e.g. Acacia mearnsii in many degraded areas, resulting in significant loss of ecosystem service capacity, along with soil and land productivity. Short-duration overnight kraaling has been suggested as a tool for restoring degraded rangelands. Recent studies in semi-arid savannas and shrublands have reported increased grass cover, soil nutrients and palatability and concluded that short-duration kraaling is a low-cost and effective way of restoring degraded rangelands using livestock. However, the response of different plant functional types and communities to such intense livestock impact may vary depending on local context. This study used twelve paired kraal and control sites to investigate the effects of short-duration (7-24 days) overnight kraaling of livestock on herbaceous vegetation and soils in a mesic grassland. The study area is generally considered to be overgrazed but has considerable variation in grass composition and basal cover. Sites included relatively intact natural grassland and sites where wattle infestations had been cleared and where mostly bare ground remained. I tested the hypotheses that overnight kraaling would result in (1) increased basal cover due to introduction of grass seed and stimulation of germination through hoof action, (2) increased infiltration due to hoof action, and (3) increased soil nutrients and organic matter due to dung and urine deposition. I also hypothesized that factors such as a site’s initial grass cover, its slope, the occurrence and amount of rainfall before and during kraaling, and the kraaling intensity (number of livestock and duration of the kraaling event) would influence the magnitude and direction of the kraaling effect. The effect of kraaling on vegetation was strongly dependent on initial condition. Kraaling increased basal cover of grasses when sites had low initial basal cover, but decreased basal cover if initial values were over 50%. Infiltration increased if kraaling took place during or after rain but decreased if kraaling took place when soils were dry. Kraaling increased soil P and K. In mesic grasslands, short-duration overnight kraaling is promising as a tool for rehabilitating degraded sites but should be avoided where the grass sward is relatively intact. I recommend that the suitability of kraaling be further evaluated per vegetation type and local context. , Thesis (MSc) -- Faculty of Science, Botany, 2023
- Full Text:
- Date Issued: 2023-10-13
An evaluation of hibiscus sabdariffa gold nanoparticles for the treatment of triple negative breast cancer
- Authors: Reddy, Nireshini
- Date: 2022-12
- Subjects: Breast--Cancer--Treatment--Technological innovations , Nanomedicine – South Africa , Roselle
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59945 , vital:62697
- Description: Cancer is responsible for the millions of deaths worldwide every year, being ranked as the second leading cause of mortality in the world. Triple negative breast cancer (TNBC) is the most severe type of breast cancer, as it is the most aggressive and difficult to treat. Current treatment methods involve surgery, hormonal-, radiation- and chemotherapy. These are costly and often have severe adverse effects. There has been increasing research in the development of alternative treatment methods to reduce the side effects of cancer therapeutics, as well as the cost. The rapidly growing field of nanotechnology has allowed for the incorporation of several diagnostic, targeting, and therapeutic agents into nanomaterials for cancer treatment. The application of gold nanoparticles (AuNPs) in the diagnosis and treatment of various types of cancers has been widely investigated. AuNPs vary in size, shape, and structure, allowing for the development of diverse formulations for various treatments. The use of green materials, particularly plant material, to synthesise nanomaterials has allowed for the safe, cost-friendly and eco-friendly production of AuNPs that can be used to treat TNBC. The aim of this study was to evaluate the efficiency of green AuNPs synthesised with Hibiscus sabdariffa to treat TNBC in a pilot murine model. Spherical AuNPs were synthesised using an aqueous extract of the calyces of this plant. The AuNPs were characterised using UV-Vis spectrometry, dynamic light scattering, high resolution – transmission electron microscopy, and in vitro stability testing. A cell viability assay showed that these AuNPs exhibited cytotoxicity towards E0771 cells in a dose-dependent manner, where cells treated with the highest concentration of AuNPs (250 µg/mL) exhibited the lowest cell viability (7%). During the in vivo pilot study, C57BL/6 mice were inoculated with TNBC using the E0771 cells. It was found that TNBC had rapidly spread, resulting in metastasis in the liver, as well as omentum and mesentery. This resulted in a number of mice dying; therefore, shortening treatment time of the AuNPs. It is suggested that AuNP treatment may have exacerbated mouse death by promoting ROS production in metastasised tissue, suggesting that AuNP treatment may not be suitable for stage 4 TNBC. Tumor analysis of caspase-3 content showed that the AuNPs exhibited potential pro-apoptotic activity in the tumours, prompting further research into the tumour uptake and apoptotic mechanism of these AuNPs. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Reddy, Nireshini
- Date: 2022-12
- Subjects: Breast--Cancer--Treatment--Technological innovations , Nanomedicine – South Africa , Roselle
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59945 , vital:62697
- Description: Cancer is responsible for the millions of deaths worldwide every year, being ranked as the second leading cause of mortality in the world. Triple negative breast cancer (TNBC) is the most severe type of breast cancer, as it is the most aggressive and difficult to treat. Current treatment methods involve surgery, hormonal-, radiation- and chemotherapy. These are costly and often have severe adverse effects. There has been increasing research in the development of alternative treatment methods to reduce the side effects of cancer therapeutics, as well as the cost. The rapidly growing field of nanotechnology has allowed for the incorporation of several diagnostic, targeting, and therapeutic agents into nanomaterials for cancer treatment. The application of gold nanoparticles (AuNPs) in the diagnosis and treatment of various types of cancers has been widely investigated. AuNPs vary in size, shape, and structure, allowing for the development of diverse formulations for various treatments. The use of green materials, particularly plant material, to synthesise nanomaterials has allowed for the safe, cost-friendly and eco-friendly production of AuNPs that can be used to treat TNBC. The aim of this study was to evaluate the efficiency of green AuNPs synthesised with Hibiscus sabdariffa to treat TNBC in a pilot murine model. Spherical AuNPs were synthesised using an aqueous extract of the calyces of this plant. The AuNPs were characterised using UV-Vis spectrometry, dynamic light scattering, high resolution – transmission electron microscopy, and in vitro stability testing. A cell viability assay showed that these AuNPs exhibited cytotoxicity towards E0771 cells in a dose-dependent manner, where cells treated with the highest concentration of AuNPs (250 µg/mL) exhibited the lowest cell viability (7%). During the in vivo pilot study, C57BL/6 mice were inoculated with TNBC using the E0771 cells. It was found that TNBC had rapidly spread, resulting in metastasis in the liver, as well as omentum and mesentery. This resulted in a number of mice dying; therefore, shortening treatment time of the AuNPs. It is suggested that AuNP treatment may have exacerbated mouse death by promoting ROS production in metastasised tissue, suggesting that AuNP treatment may not be suitable for stage 4 TNBC. Tumor analysis of caspase-3 content showed that the AuNPs exhibited potential pro-apoptotic activity in the tumours, prompting further research into the tumour uptake and apoptotic mechanism of these AuNPs. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-12
Effects of Lignin on the properties of reclaimed rubber /natural rubber blends
- Makhelema, Junith Matshidiso
- Authors: Makhelema, Junith Matshidiso
- Date: 2022-12
- Subjects: Lignin – South Africa , Tires – Recycling
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59744 , vital:62409
- Description: The environmental challenge posed by waste tyres is a serious global crisis from which South Africa is not isolated. The concept of tyre rubber reclamation into reusable rubber over the years has been on the increase, however, despite the environmental and economic advantages offered by the reclaiming process the main demerits of the resulting rubber include its relatively poor physical and mechanical properties when compared to newly manufactured rubber. The deterioration of these properties arises from the structural changes which occur during the reclaiming process. To overcome this disadvantage, reclaimed rubber can be blended with other rubbers such as natural rubber to compensate for its weak properties. However, there is stilll a limited industrial application of reclaimed/natural rubber blends due to their brittleness and relatively poor impact strength. By adding reinforcing fillers, the mechanical properties of the blends can be significantly improved. In recent years, there has been a renewed interest in the use of lignocellulosic materials as fillers, modifiers and reinforcements in polymeric materials. They are receiving attention because they are the most abundantly available raw materials on earth, and they offer greater versatility compared to inorganic fillers. Being the most abundant renewable agricultural derived lignocellulosic biomass after cellulose, and as far as polymer composites and blends are concerned, lignin has shown promise as a well-received and sustainable alternative to inorganic fillers due to its low-cost production and ability to improve on the biodegradability of polyolefins and minimise loss of ultimate mechanical properties of polymer matrices. The main aim of the research is to investigate the effect of lignin on the properties of reclaimed/natural rubber (RR/NR) blends for possible low-density and eco-friendly rubber materials. The motivation for the research arises from the global challenges that are connected to the dynamic increase of rubber wastes, especially in the form of used tyres and the potential availability of lignin from its annual production from the sugarcane pulp mills, which is regarded as waste. A mixture design of experiments was used to formulate different blends of lignin with reclaimed and natural rubber. The rubber blends and the lignin-rubber , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Makhelema, Junith Matshidiso
- Date: 2022-12
- Subjects: Lignin – South Africa , Tires – Recycling
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59744 , vital:62409
- Description: The environmental challenge posed by waste tyres is a serious global crisis from which South Africa is not isolated. The concept of tyre rubber reclamation into reusable rubber over the years has been on the increase, however, despite the environmental and economic advantages offered by the reclaiming process the main demerits of the resulting rubber include its relatively poor physical and mechanical properties when compared to newly manufactured rubber. The deterioration of these properties arises from the structural changes which occur during the reclaiming process. To overcome this disadvantage, reclaimed rubber can be blended with other rubbers such as natural rubber to compensate for its weak properties. However, there is stilll a limited industrial application of reclaimed/natural rubber blends due to their brittleness and relatively poor impact strength. By adding reinforcing fillers, the mechanical properties of the blends can be significantly improved. In recent years, there has been a renewed interest in the use of lignocellulosic materials as fillers, modifiers and reinforcements in polymeric materials. They are receiving attention because they are the most abundantly available raw materials on earth, and they offer greater versatility compared to inorganic fillers. Being the most abundant renewable agricultural derived lignocellulosic biomass after cellulose, and as far as polymer composites and blends are concerned, lignin has shown promise as a well-received and sustainable alternative to inorganic fillers due to its low-cost production and ability to improve on the biodegradability of polyolefins and minimise loss of ultimate mechanical properties of polymer matrices. The main aim of the research is to investigate the effect of lignin on the properties of reclaimed/natural rubber (RR/NR) blends for possible low-density and eco-friendly rubber materials. The motivation for the research arises from the global challenges that are connected to the dynamic increase of rubber wastes, especially in the form of used tyres and the potential availability of lignin from its annual production from the sugarcane pulp mills, which is regarded as waste. A mixture design of experiments was used to formulate different blends of lignin with reclaimed and natural rubber. The rubber blends and the lignin-rubber , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-12
Does the Transkei population of Haliotis Midae at the eastern edge of its distributional range have a higher thermal tolerance than those in more temperate waters?
- Authors: Mathebula, Surprise
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa -- Indian Coast , Abalones -- South Africa -- Indian Coast , Haliotis midae -- Effect of temperature on -- South Africa -- Indian Coast , Haliotis midae -- Physiology -- South Africa -- Indian Coast , Haliotis midae -- Adaptation -- South Africa -- Indian Coast , Haliotis midae -- Growth -- South Africa -- Indian Coast
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177360 , vital:42814
- Description: The South African perlemoen abalone (Haliotis midae) may be vulnerable to rising temperatures on the East coast of South Africa due to climate change. H. midae is South Africa’s most valuable aquaculture species, and it is thus important to understand its physiological ability to adapt to the expected changes and to identify possible management measures to mitigate the impacts of rising temperatures. This project aimed to understand thermal tolerance and growth rates of offspring from two H. midae populations originating from the warm-temperate Central region (Port Elizabeth) and warmer Eastern edge of the species’ distribution in the Transkei region. To determine the effects of temperature on the physiological performance of the two abalone populations, growth rates, oxygen consumption rates and critical thermal maxima (CTM) were compared. A laboratory growth trial was conducted at three controlled temperatures, visibly, the ‘optimal’ temperature for H. midae growth (18 - 20℃), ‘pejus’ (stressful) temperature (21 - 22℃) and ‘critical’ temperature (23 - 24℃). Oxygen consumption rates were recorded at optimum (20℃), pejus (22℃) and critical (24℃) temperature using a respirometer. In addition, a farm growth trial with simultaneously spawned cohorts of abalone from the two populations was conducted at ambient temperature (19.5 and 20.0℃). The laboratory growth trial revealed no significant differences in growth rate between the two populations at the three temperature treatments (ANOVA, P > 0.05; df = 2). However, mortalities were high and growth rates low, indicating that the rearing conditions were sub-optimal, possibly masking genetic differences. No significant differences were observed in oxygen consumption rates (ANOVA, P = 0.18; df = 2), and CTM (t-Test, P = 0.31; df = 3) between the two populations. The CTM for both populations was between 29 - 30℃. The farm trial yielded no significant differences in growth rate during the Nursery phase (t-Test, P = 0.25; df = 2), however significant differences in growth rate were observed during the grow out phase with the Central region abalone offspring growing faster than the Eastern edge population (t-Test, P = 0.04; df = 4) indicating the possibility of a genetic difference between the two populations. Further experiments will be required to determine whether the differences observed in the growth trial were genetically or environmentally induced. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mathebula, Surprise
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa -- Indian Coast , Abalones -- South Africa -- Indian Coast , Haliotis midae -- Effect of temperature on -- South Africa -- Indian Coast , Haliotis midae -- Physiology -- South Africa -- Indian Coast , Haliotis midae -- Adaptation -- South Africa -- Indian Coast , Haliotis midae -- Growth -- South Africa -- Indian Coast
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177360 , vital:42814
- Description: The South African perlemoen abalone (Haliotis midae) may be vulnerable to rising temperatures on the East coast of South Africa due to climate change. H. midae is South Africa’s most valuable aquaculture species, and it is thus important to understand its physiological ability to adapt to the expected changes and to identify possible management measures to mitigate the impacts of rising temperatures. This project aimed to understand thermal tolerance and growth rates of offspring from two H. midae populations originating from the warm-temperate Central region (Port Elizabeth) and warmer Eastern edge of the species’ distribution in the Transkei region. To determine the effects of temperature on the physiological performance of the two abalone populations, growth rates, oxygen consumption rates and critical thermal maxima (CTM) were compared. A laboratory growth trial was conducted at three controlled temperatures, visibly, the ‘optimal’ temperature for H. midae growth (18 - 20℃), ‘pejus’ (stressful) temperature (21 - 22℃) and ‘critical’ temperature (23 - 24℃). Oxygen consumption rates were recorded at optimum (20℃), pejus (22℃) and critical (24℃) temperature using a respirometer. In addition, a farm growth trial with simultaneously spawned cohorts of abalone from the two populations was conducted at ambient temperature (19.5 and 20.0℃). The laboratory growth trial revealed no significant differences in growth rate between the two populations at the three temperature treatments (ANOVA, P > 0.05; df = 2). However, mortalities were high and growth rates low, indicating that the rearing conditions were sub-optimal, possibly masking genetic differences. No significant differences were observed in oxygen consumption rates (ANOVA, P = 0.18; df = 2), and CTM (t-Test, P = 0.31; df = 3) between the two populations. The CTM for both populations was between 29 - 30℃. The farm trial yielded no significant differences in growth rate during the Nursery phase (t-Test, P = 0.25; df = 2), however significant differences in growth rate were observed during the grow out phase with the Central region abalone offspring growing faster than the Eastern edge population (t-Test, P = 0.04; df = 4) indicating the possibility of a genetic difference between the two populations. Further experiments will be required to determine whether the differences observed in the growth trial were genetically or environmentally induced. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
Night-time gravity waves detected with multi-frequency airglow imager
- Authors: Machubeng, Karabo Pebane
- Date: 2021-04
- Subjects: Gravity waves , Airglow , Gravity waves -- Seasonal variations , All Sky Imager
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178341 , vital:42931
- Description: This thesis shows the statistics of atmospheric gravity waves (AGWs) observed in the OI emission 557.7 nm at _97 km altitude using an all-sky imager based in Sutherland, South Africa (32.37_ S, 20.81_ E) in the year 2017. The wavelengths were determined using the propagation vector method, velocity was determined using the cross correlation of 1D FFT and the period was determined using the equation that relates wavelength and velocity. It was found that the horizontal wavelength in summer was almost evenly distributed between 10 and 40 km and for autumn, winter and spring were mostly between 10 and 30 km. The favoured speeds were between 40 and 50 m/s in autumn, as well as 30 and 50 m/s in summer, but the AGWs in winter had a bimodal speed distribution of 20 - 40 and 50 - 70 m/s. The majority of periods observed in all seasons were less than 20 minutes with a dominant peak of 5 - 10 minutes in autumn and spring. There was no favoured propagation direction for spring, but AGWs favoured a southeastward propagation in summer, and a southward propagation in autumn and winter. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Machubeng, Karabo Pebane
- Date: 2021-04
- Subjects: Gravity waves , Airglow , Gravity waves -- Seasonal variations , All Sky Imager
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178341 , vital:42931
- Description: This thesis shows the statistics of atmospheric gravity waves (AGWs) observed in the OI emission 557.7 nm at _97 km altitude using an all-sky imager based in Sutherland, South Africa (32.37_ S, 20.81_ E) in the year 2017. The wavelengths were determined using the propagation vector method, velocity was determined using the cross correlation of 1D FFT and the period was determined using the equation that relates wavelength and velocity. It was found that the horizontal wavelength in summer was almost evenly distributed between 10 and 40 km and for autumn, winter and spring were mostly between 10 and 30 km. The favoured speeds were between 40 and 50 m/s in autumn, as well as 30 and 50 m/s in summer, but the AGWs in winter had a bimodal speed distribution of 20 - 40 and 50 - 70 m/s. The majority of periods observed in all seasons were less than 20 minutes with a dominant peak of 5 - 10 minutes in autumn and spring. There was no favoured propagation direction for spring, but AGWs favoured a southeastward propagation in summer, and a southward propagation in autumn and winter. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
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