Linking agrochemical pollution with the aquatic ecological integrity of the Twee River Catchment, Western Cape
- Authors: Brink, Zanné
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52326 , vital:43588
- Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Brink, Zanné
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52326 , vital:43588
- Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Large mammalian fauna of the Palaeo-Agulhas Plain: predicting habitat use and range distribution
- Authors: Brooke, Christopher F
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Herbivores
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52332 , vital:43590
- Description: Understanding the variations in structure and abundance of animals and what leads to their distribution within the landscape has captured the attention of ecologists for centuries. Importantly, knowledge of current behaviour of large mammals can be used to inform historic population dynamics and is essential to understanding how early humans used large mammals as a foraging resource. Central to this thesis and improving our understanding of large herbivores is the Palaeo-Agulhas Plain (PAP) where large mammalian herbivores formed a key food resource for early humans. The PAP, now submerged off the southern Cape of South Africa, formed a novel ecosystem during lower sea levels. Characterised by large expanses of nutrient rich grasslands and large grazing herbivores, the PAP stands in stark contrast to the nutrient poor fynbos ecosystems that is in the southern Cape today. In this thesis I focus on the Last Glacial Maximum (LGM; ~20 ka) when the PAP was last fully exposed to answer questions relating to the habitat use and range distribution of large herbivores. Importantly, through the Paleoscape Project, modelled climate, soil and vegetation have made these recreations of large mammals possible. Using modelled climate and vegetation this thesis aims to model the large herbivore communities and understand the influence of early humans on the PAP during the LGM for successful integration into the PaleoscapeABM (the PAP agent-based model). To improve our understanding of large mammals on the PAP I identified five large herbivores that became extinct on the PAP since the LGM and modelled their behavioural and physical traits using k-Nearest Neighbour imputation. I predicted the biomass of large herbivores across the PAP using actual biomass of large herbivores from 39 protected areas across South Africa (spanning five functional groups to include the extinct species) across a rainfall gradient and different biomes. The distribution of large herbivores would likely have been driven by similar top-down and bottom-up drivers we see in large herbivore ecology today. Knowing this, I created a predictive model for large mammals by predicting the probability of occurrence of functional groups of large herbivores in relation to environmental drivers and humans. Results showed that all species (except Antidorcas australis) were adapted to the grassy environment of the PAP and these specialisations likely contributed to their extinction along with changing climates and intensified hunting from humans. When predicting herbivore viii biomass, biome was the most important factor influencing the relationship between herbivores and rainfall. In general, large herbivore biomass increased with rainfall across biomes, except for grassland. Finally, I showed the probability of occurrence of large herbivores was influenced by early humans, water availability and a landscape of fear on the PAP. Through this thesis I have successfully provided detailed accounts of the biomass and probability of occurrence of large herbivores on the PAP. Importantly, this information can be seamlessly integrated into the PaleoscapeABM. Finally, I highlight the importance of this knowledge in understanding early humans, the potential shortcomings of this study and resulting areas where research needs to be focused. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Brooke, Christopher F
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Herbivores
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52332 , vital:43590
- Description: Understanding the variations in structure and abundance of animals and what leads to their distribution within the landscape has captured the attention of ecologists for centuries. Importantly, knowledge of current behaviour of large mammals can be used to inform historic population dynamics and is essential to understanding how early humans used large mammals as a foraging resource. Central to this thesis and improving our understanding of large herbivores is the Palaeo-Agulhas Plain (PAP) where large mammalian herbivores formed a key food resource for early humans. The PAP, now submerged off the southern Cape of South Africa, formed a novel ecosystem during lower sea levels. Characterised by large expanses of nutrient rich grasslands and large grazing herbivores, the PAP stands in stark contrast to the nutrient poor fynbos ecosystems that is in the southern Cape today. In this thesis I focus on the Last Glacial Maximum (LGM; ~20 ka) when the PAP was last fully exposed to answer questions relating to the habitat use and range distribution of large herbivores. Importantly, through the Paleoscape Project, modelled climate, soil and vegetation have made these recreations of large mammals possible. Using modelled climate and vegetation this thesis aims to model the large herbivore communities and understand the influence of early humans on the PAP during the LGM for successful integration into the PaleoscapeABM (the PAP agent-based model). To improve our understanding of large mammals on the PAP I identified five large herbivores that became extinct on the PAP since the LGM and modelled their behavioural and physical traits using k-Nearest Neighbour imputation. I predicted the biomass of large herbivores across the PAP using actual biomass of large herbivores from 39 protected areas across South Africa (spanning five functional groups to include the extinct species) across a rainfall gradient and different biomes. The distribution of large herbivores would likely have been driven by similar top-down and bottom-up drivers we see in large herbivore ecology today. Knowing this, I created a predictive model for large mammals by predicting the probability of occurrence of functional groups of large herbivores in relation to environmental drivers and humans. Results showed that all species (except Antidorcas australis) were adapted to the grassy environment of the PAP and these specialisations likely contributed to their extinction along with changing climates and intensified hunting from humans. When predicting herbivore viii biomass, biome was the most important factor influencing the relationship between herbivores and rainfall. In general, large herbivore biomass increased with rainfall across biomes, except for grassland. Finally, I showed the probability of occurrence of large herbivores was influenced by early humans, water availability and a landscape of fear on the PAP. Through this thesis I have successfully provided detailed accounts of the biomass and probability of occurrence of large herbivores on the PAP. Importantly, this information can be seamlessly integrated into the PaleoscapeABM. Finally, I highlight the importance of this knowledge in understanding early humans, the potential shortcomings of this study and resulting areas where research needs to be focused. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
An assessment of different methods for measuring mammal diversity in two Southern African arid ecosystems.
- Authors: Burt, Chloe
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52338 , vital:43591
- Description: A current critical environmental problem is the loss of biodiversity. To allow for adaptive management and effective conservation interventions, reliable data needs to be readily available and effectively collected. To gather reliable data, the most appropriate method must be used. The aim of this thesis was to compare the effectiveness and efficiency of different mammal diversity sampling techniques, including discussing specificities and complementarity of each. I also assessed the limitation of methods in terms of the influence of species traits on detectability. I used standard mammal field methods such as block transects, camera traps, track plates, spotlight surveys, mist nets, acoustic surveys, and live traps for a wide range of mammal taxa, and also included the use of local knowledge in the comparison. I assessed the cost-efficiency of each method by determining the cost per species. The efficiency of each method was assessed by observing when the species accumulation curve reached an asymptote. The effectiveness was determined by the species richness and the taxonomic groups the method detected. My results indicated that block transects were the most efficient and effective method to assess species richness. However, a combination of methods allowed for a more comprehensive survey and my results indicate that block transects and live traps were the best combination. It is important to note, not only the effectiveness and efficiency of methods be assessed, but also their limitations. I therefore also assessed the influence of species traits on the detectability of five methods. The species traits that I tested were body size, diet, activity, and if they lived in groups. On both study areas, body size was the main trait that influenced detectability with most field methods. Diet and activity had varying influence on detectability depending on the method. Group living did not significantly influence detectability. Based on my results, I provide guidelines for choosing the most appropriate survey method for targeted studies on mammals in arid ecosystems as well as guidelines for choosing the most appropriate methods for a terrestrial mammal inventory. Survey methods selection and guidelines provided here can allow for effective monitoring and therefore effective and adaptive management and having reliable and repeatable outcomes from surveys. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Burt, Chloe
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52338 , vital:43591
- Description: A current critical environmental problem is the loss of biodiversity. To allow for adaptive management and effective conservation interventions, reliable data needs to be readily available and effectively collected. To gather reliable data, the most appropriate method must be used. The aim of this thesis was to compare the effectiveness and efficiency of different mammal diversity sampling techniques, including discussing specificities and complementarity of each. I also assessed the limitation of methods in terms of the influence of species traits on detectability. I used standard mammal field methods such as block transects, camera traps, track plates, spotlight surveys, mist nets, acoustic surveys, and live traps for a wide range of mammal taxa, and also included the use of local knowledge in the comparison. I assessed the cost-efficiency of each method by determining the cost per species. The efficiency of each method was assessed by observing when the species accumulation curve reached an asymptote. The effectiveness was determined by the species richness and the taxonomic groups the method detected. My results indicated that block transects were the most efficient and effective method to assess species richness. However, a combination of methods allowed for a more comprehensive survey and my results indicate that block transects and live traps were the best combination. It is important to note, not only the effectiveness and efficiency of methods be assessed, but also their limitations. I therefore also assessed the influence of species traits on the detectability of five methods. The species traits that I tested were body size, diet, activity, and if they lived in groups. On both study areas, body size was the main trait that influenced detectability with most field methods. Diet and activity had varying influence on detectability depending on the method. Group living did not significantly influence detectability. Based on my results, I provide guidelines for choosing the most appropriate survey method for targeted studies on mammals in arid ecosystems as well as guidelines for choosing the most appropriate methods for a terrestrial mammal inventory. Survey methods selection and guidelines provided here can allow for effective monitoring and therefore effective and adaptive management and having reliable and repeatable outcomes from surveys. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Fragmentation of the Albany Thicket Biome: consequences for the biodiversity and health of thicket vegetation
- Authors: Carvalho, Shandon Luke
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fragmented landscapes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52344 , vital:43599
- Description: The dense impenetrable vegetation of the Albany Thicket Biome is highly resistant to a wide variety of disturbances but, once disturbed, lacks the regenerative qualities that allow it to return to a stable state. Agricultural development is the main cause of degradation in this biome, creating a landscape consisting of patches of thicket vegetation scattered throughout land cleared for crops or transformed through grazing by domestic livestock. The main objective of this study is to determine the health, status and biodiversity of thicket fragments as it relates to elephant impacts. The level of fragmentation and the remaining extent of intact thicket were investigated as its current status is unknown. The findings suggest that the Thicket Biome is highly fragmented as almost 50% of solid thicket has been cleared, transformed or degraded by agricultural or urban development. For Arid Thicket, the level of fragmentation and the remaining extent of intact thicket could not be determined and both could potentially be greater. For the intact thicket of Dune, Mesic and Valley Thicket types, patch sizes ranged between almost 6 and 876 km2 while the weighted mean was between 2 and 251 km2 . Remote sensing methods (NDVI) were used to determine whether the health of thicket could be remotely assessed. The thicket within and beyond the extent of piospheres around watering holes is subjected to different levels of herbivory. These different levels were compared to corresponding NDVI values with the latter accurately measuring the impact of herbivores along a gradient and providing a method to assess the health of thicket vegetation. Ground surveys of the edge effect, along thicket fragments adjacent to open pastures and separated by cut lines, were conducted. Based on these surveys, the extent of the edge effect was established at a distance of 7 m into thicket fragments separated by cut lines but could not be determined for thicket fragments adjacent to open pastures. Ground surveys were also conducted to assess the health of thicket vegetation exposed to different levels of herbivory, including the impact of elephants (Loxodonta africana). Results showed that different elephant densities produced different levels of impact that could be described in terms of changes in species richness, species diversity, plant height and cover, and growth form composition. Lastly, the findings of the health-based assessments were combined with elephant densities to develop a model that could assess the health of thicket vegetation using a range of ecological variables and relate it to an ideal range of elephant densities. This assessment method was tested at the Addo Elephant National Park and results showed that an elephant density of 1 elephant/km2 would maintain the appropriate diversity, structure and composition of thicket. , Thesis (MSc) -- Faculty of Science, Department of Botany, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Carvalho, Shandon Luke
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fragmented landscapes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52344 , vital:43599
- Description: The dense impenetrable vegetation of the Albany Thicket Biome is highly resistant to a wide variety of disturbances but, once disturbed, lacks the regenerative qualities that allow it to return to a stable state. Agricultural development is the main cause of degradation in this biome, creating a landscape consisting of patches of thicket vegetation scattered throughout land cleared for crops or transformed through grazing by domestic livestock. The main objective of this study is to determine the health, status and biodiversity of thicket fragments as it relates to elephant impacts. The level of fragmentation and the remaining extent of intact thicket were investigated as its current status is unknown. The findings suggest that the Thicket Biome is highly fragmented as almost 50% of solid thicket has been cleared, transformed or degraded by agricultural or urban development. For Arid Thicket, the level of fragmentation and the remaining extent of intact thicket could not be determined and both could potentially be greater. For the intact thicket of Dune, Mesic and Valley Thicket types, patch sizes ranged between almost 6 and 876 km2 while the weighted mean was between 2 and 251 km2 . Remote sensing methods (NDVI) were used to determine whether the health of thicket could be remotely assessed. The thicket within and beyond the extent of piospheres around watering holes is subjected to different levels of herbivory. These different levels were compared to corresponding NDVI values with the latter accurately measuring the impact of herbivores along a gradient and providing a method to assess the health of thicket vegetation. Ground surveys of the edge effect, along thicket fragments adjacent to open pastures and separated by cut lines, were conducted. Based on these surveys, the extent of the edge effect was established at a distance of 7 m into thicket fragments separated by cut lines but could not be determined for thicket fragments adjacent to open pastures. Ground surveys were also conducted to assess the health of thicket vegetation exposed to different levels of herbivory, including the impact of elephants (Loxodonta africana). Results showed that different elephant densities produced different levels of impact that could be described in terms of changes in species richness, species diversity, plant height and cover, and growth form composition. Lastly, the findings of the health-based assessments were combined with elephant densities to develop a model that could assess the health of thicket vegetation using a range of ecological variables and relate it to an ideal range of elephant densities. This assessment method was tested at the Addo Elephant National Park and results showed that an elephant density of 1 elephant/km2 would maintain the appropriate diversity, structure and composition of thicket. , Thesis (MSc) -- Faculty of Science, Department of Botany, 2021
- Full Text: false
- Date Issued: 2021-04
Incidence of parasitic trematodes effects on the energetics and behaviour of Coryogalops sordidus (Family: Gobiidae) resident in microbialite pools, warm temperate South Africa
- Authors: Du Toit, Hendrik Daniël
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Gobiidae -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52458 , vital:43666
- Description: Coryogalops sordidus(Epaulette goby), is a cryptobenthic species of the Family Gobiidae that iscommonly foundoccupying turbulent surf zones, calm rock pools, and sand and mud flats, where they are generally carnivorous predators. The distribution of C. sordidushas been recorded for Kenya, Tanzania, Mozambique, and South Africa. The species is also resident in the microbialite pools on the temperate south east coast of South Africa. Recent reports indicated these gobies to be covered in numerous dark lesions, possibly suggesting that the microbialite pools are a sub-optimal habitat. Preliminary analyses have indicated that the dark lesions are a result of encysted metacercaria of a digenetic trematode (fluke). There werehowever,no current recorded parasiticspecies occurring within microbialite pool nor any records of any parasitic species utilizingC. sordidus as a host in South Africa. Therefore, the aim of this study was to investigate parasite-host interactions and parasite presence in and around themicrobialite pool systems of Algoa Bay using C. sordidusas a study species. Coryogalops sordiduswas identified to be parasitised by digenetic trematode metacercaria of the Family Diplostomidae Poirier, 1886, localised primarily to the host musculature, fins, eyes, and integument with no settlement on any of the visceral organs. Furthermore, C. sordidus was found additionally parasitised by a green leech (Class: Hirundinea) of the Family Piscicolidae Johnston, 1865, localised exclusively to the ventral body surface, underneath the pelvic fin of the host. Further investigation into the life cycle of the trematode, suggested that the most probable final hosts wereherons,namely Ardea cinereaand Egretta garzetta garzetta, and intermediate host likely being the freshwater gastropod Assimineacf.capensis, present inthe upper microbialite pools. In both the microbialite and neighbouring rock pools trematode prevalence was found to oscillate in response to seasonal chemical and climatic conditions, whereas the secondary piscicolid leech parasite was influencedmoreby host presence than environmental conditions. Greater prevalence and intensity were measured in the microbialite pools suggesting that these systems likely contained a suit of favourable conditions that allowed for greater trematode loads to be maintained as compared to neighbouring rock pools. As parasites often have deleterious effects on their hosts, the response can manifest as an altered host behaviour or an increased energetic debt due to elevated immune response activity and the associated cost of tissue repair at sites of parasite aggregation.This study further investigatedifgobies (C. sordidus) infected with metacercarial cysts display higher metabolic ratesordifferent swimming behaviour compared to non-infected individuals. The results indicated that the metacercarial load carried by infected hosts had on average no significant impact on energetics, swimming ability, or swimming behaviour, concluding that the average metacercarial intensity present on the gobies is therefore below the threshold of an altered host response. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Du Toit, Hendrik Daniël
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Gobiidae -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52458 , vital:43666
- Description: Coryogalops sordidus(Epaulette goby), is a cryptobenthic species of the Family Gobiidae that iscommonly foundoccupying turbulent surf zones, calm rock pools, and sand and mud flats, where they are generally carnivorous predators. The distribution of C. sordidushas been recorded for Kenya, Tanzania, Mozambique, and South Africa. The species is also resident in the microbialite pools on the temperate south east coast of South Africa. Recent reports indicated these gobies to be covered in numerous dark lesions, possibly suggesting that the microbialite pools are a sub-optimal habitat. Preliminary analyses have indicated that the dark lesions are a result of encysted metacercaria of a digenetic trematode (fluke). There werehowever,no current recorded parasiticspecies occurring within microbialite pool nor any records of any parasitic species utilizingC. sordidus as a host in South Africa. Therefore, the aim of this study was to investigate parasite-host interactions and parasite presence in and around themicrobialite pool systems of Algoa Bay using C. sordidusas a study species. Coryogalops sordiduswas identified to be parasitised by digenetic trematode metacercaria of the Family Diplostomidae Poirier, 1886, localised primarily to the host musculature, fins, eyes, and integument with no settlement on any of the visceral organs. Furthermore, C. sordidus was found additionally parasitised by a green leech (Class: Hirundinea) of the Family Piscicolidae Johnston, 1865, localised exclusively to the ventral body surface, underneath the pelvic fin of the host. Further investigation into the life cycle of the trematode, suggested that the most probable final hosts wereherons,namely Ardea cinereaand Egretta garzetta garzetta, and intermediate host likely being the freshwater gastropod Assimineacf.capensis, present inthe upper microbialite pools. In both the microbialite and neighbouring rock pools trematode prevalence was found to oscillate in response to seasonal chemical and climatic conditions, whereas the secondary piscicolid leech parasite was influencedmoreby host presence than environmental conditions. Greater prevalence and intensity were measured in the microbialite pools suggesting that these systems likely contained a suit of favourable conditions that allowed for greater trematode loads to be maintained as compared to neighbouring rock pools. As parasites often have deleterious effects on their hosts, the response can manifest as an altered host behaviour or an increased energetic debt due to elevated immune response activity and the associated cost of tissue repair at sites of parasite aggregation.This study further investigatedifgobies (C. sordidus) infected with metacercarial cysts display higher metabolic ratesordifferent swimming behaviour compared to non-infected individuals. The results indicated that the metacercarial load carried by infected hosts had on average no significant impact on energetics, swimming ability, or swimming behaviour, concluding that the average metacercarial intensity present on the gobies is therefore below the threshold of an altered host response. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-04
Bayesian tolerance intervals and their application to ballistic grouping consistency in competitive shooting
- Authors: Gardiner, Marcell
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Bayesian statistical decision theory -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52456 , vital:43662
- Description: Competitive shooting has become immensely popular since the first modern Games held in 1896. Competitive shooting remains the fastest growing segment in the firearm industry, catering to individuals of all ages. Elite shooters are capable of reaching extreme levels of precision and accuracy, despite many factors existing that affect performance in Olympic shooting. One such factor is speed variability, which is dependent on the mass of the bullet, how constant is the lead being used, and, how constant the gunpowder is. The study focusses on the Bayesian simulation method proposed by Wolfinger (1998) for determining three kinds of tolerance intervals when applied to competitive shooting data, particularly examining speed variability. These tolerance intervals included the (𝛼𝛼,𝛿𝛿) tolerance interval (where 𝛼𝛼 is the content and 𝛿𝛿 is the confidence), the 𝛼𝛼 - expectation tolerance interval (where 𝛼𝛼 is the expected coverage of the interval) and the fixed-in advance tolerance interval in which the interval is held fixed and the proportion of process measurements it contains, is estimated. Speed measurements of individual shots fired were measured with either an Oeler 35P or Magneto Speed V3 chronograph and the data was fitted to a one-way random effects model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Gardiner, Marcell
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Bayesian statistical decision theory -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52456 , vital:43662
- Description: Competitive shooting has become immensely popular since the first modern Games held in 1896. Competitive shooting remains the fastest growing segment in the firearm industry, catering to individuals of all ages. Elite shooters are capable of reaching extreme levels of precision and accuracy, despite many factors existing that affect performance in Olympic shooting. One such factor is speed variability, which is dependent on the mass of the bullet, how constant is the lead being used, and, how constant the gunpowder is. The study focusses on the Bayesian simulation method proposed by Wolfinger (1998) for determining three kinds of tolerance intervals when applied to competitive shooting data, particularly examining speed variability. These tolerance intervals included the (𝛼𝛼,𝛿𝛿) tolerance interval (where 𝛼𝛼 is the content and 𝛿𝛿 is the confidence), the 𝛼𝛼 - expectation tolerance interval (where 𝛼𝛼 is the expected coverage of the interval) and the fixed-in advance tolerance interval in which the interval is held fixed and the proportion of process measurements it contains, is estimated. Speed measurements of individual shots fired were measured with either an Oeler 35P or Magneto Speed V3 chronograph and the data was fitted to a one-way random effects model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-04
Synthesis of coumarin based fluorescent chemosensors for the detection of metal ions.
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Thiazole derivatives as potential hiv-1 protease inhibitors
- Authors: Hlongwe, Zola
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Enzyme kinetics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52116 , vital:43427
- Description: Series of compounds were screened using Schrodinger suite (Maestro). The DFT calculations were used for geometry optimization of the ligands using the B3YLYP functional and 6-31G basis set, and these structures were used for docking studies. Maestro was used to predict the activity of thiazole derivatives against HIV-1 protease. The range of estimated inhibition constants for these thiazole derivatives (65 nM-5 μM) indicate moderate to weak activity against HIV-1 protease, given that the activity of current protease inhibitors is typically found have experimental inhibition constants around 0.1-2.0 nM. Twenty compounds were selected based on the docking results and they were synthesized and characterized by NMR, FT-IR and elemental analysis. The cytotoxicity studies were done at two different concentrations (100 μM and 10 μM), using the brine shrimp bioassay. All compounds were highly toxic at 100 μM, with the percentage mortality between 20 to 75%. Eight compounds were selected for the enzyme bioassay based on the results obtained from lower concentration (10 μM). In the enzyme inhibition studies, the profile of HIV-1 activity was done at different inhibitor concentrations (800 μM – 10 μM) by measuring the cleavage of the synthetic substrate (Abz-Thr-lle-PNO2Phe=Gln-Arg-NH2) at excitation wavelength of 345/490 nm using fluorescence. Ligands 5 (unsubstituted derivative), 7 (4-nitro derivative) and 16 (4-methoxy derivative) gave percentage inhibition of 39, 45 and 42%, and this activity was very low compared to the activity of the positive control ritonavir (85% enzyme inhibition). Ligands 8 (4-methoxy derivative) and 12 (4-methoxy derivative) gave enzyme inhibition of 70% and 75%. These results suggest that the presence of the methoxy substituents ii increases activity of these compounds against HIV-1 protease. Most of the compounds gave good IC50 values between 12.5-42.7 nM. The bromo-substituted ligand 7 gave the lowest IC50 (12.5 nM). Ligand 11 also gave a good IC50 value of 14.86 nM. The bromo-substituted derivatives showed to be very active compared to other types of thiazole derivatives. Enzyme kinetics were carried out to compare the inhibition constants obtained via computational modelling. Ligand 7 (4-methoxy derivatives) binds better in the active site of HIV-1 protease than other compounds in Class B, with Ki = 50 nM, Km = 23.8 Nm and Vmax = 83.3 nM/min. The unsubstituted (L5), 4-bromo (L7) and 4-nitro (L8) substituted compounds gave inhibition constants of 100 to 112 nM. The in vitro testing yielded higher activity than that determined in silico. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Hlongwe, Zola
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Enzyme kinetics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52116 , vital:43427
- Description: Series of compounds were screened using Schrodinger suite (Maestro). The DFT calculations were used for geometry optimization of the ligands using the B3YLYP functional and 6-31G basis set, and these structures were used for docking studies. Maestro was used to predict the activity of thiazole derivatives against HIV-1 protease. The range of estimated inhibition constants for these thiazole derivatives (65 nM-5 μM) indicate moderate to weak activity against HIV-1 protease, given that the activity of current protease inhibitors is typically found have experimental inhibition constants around 0.1-2.0 nM. Twenty compounds were selected based on the docking results and they were synthesized and characterized by NMR, FT-IR and elemental analysis. The cytotoxicity studies were done at two different concentrations (100 μM and 10 μM), using the brine shrimp bioassay. All compounds were highly toxic at 100 μM, with the percentage mortality between 20 to 75%. Eight compounds were selected for the enzyme bioassay based on the results obtained from lower concentration (10 μM). In the enzyme inhibition studies, the profile of HIV-1 activity was done at different inhibitor concentrations (800 μM – 10 μM) by measuring the cleavage of the synthetic substrate (Abz-Thr-lle-PNO2Phe=Gln-Arg-NH2) at excitation wavelength of 345/490 nm using fluorescence. Ligands 5 (unsubstituted derivative), 7 (4-nitro derivative) and 16 (4-methoxy derivative) gave percentage inhibition of 39, 45 and 42%, and this activity was very low compared to the activity of the positive control ritonavir (85% enzyme inhibition). Ligands 8 (4-methoxy derivative) and 12 (4-methoxy derivative) gave enzyme inhibition of 70% and 75%. These results suggest that the presence of the methoxy substituents ii increases activity of these compounds against HIV-1 protease. Most of the compounds gave good IC50 values between 12.5-42.7 nM. The bromo-substituted ligand 7 gave the lowest IC50 (12.5 nM). Ligand 11 also gave a good IC50 value of 14.86 nM. The bromo-substituted derivatives showed to be very active compared to other types of thiazole derivatives. Enzyme kinetics were carried out to compare the inhibition constants obtained via computational modelling. Ligand 7 (4-methoxy derivatives) binds better in the active site of HIV-1 protease than other compounds in Class B, with Ki = 50 nM, Km = 23.8 Nm and Vmax = 83.3 nM/min. The unsubstituted (L5), 4-bromo (L7) and 4-nitro (L8) substituted compounds gave inhibition constants of 100 to 112 nM. The in vitro testing yielded higher activity than that determined in silico. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Estimating the population size of three large carnivore species and the diet of six large carnivore species, in Madikwe Game Reserve
- Authors: Honiball, Terry-Lee
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Carnivores
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52139 , vital:43421
- Description: Large carnivores play a vital role in ecosystems, providing ecosystem services such as herbivore regulation. If not properly monitored, carnivores could place significant pressure on certain prey species, and in extreme cases, result in the local extinction of certain species. A lack of demographic data can indirectly threaten carnivores, as policies and management decisions based on demographic data can result in the over harvesting or unsustainable hunting of large carnivores. Furthermore, their conservation is becoming confined to small, fenced, protected areas. Whereby species are intensively managed, making demographic and ecological data a fundamental part of conservation decisions. Therefore, it is essential for conservation practitioners to understand large carnivore demography and their role, to conserve them effectively. To provide Madikwe Game Reserve with the necessary data for effective long-term monitoring and management of the large carnivore guild, I estimated the population size of the cryptic carnivores. I then investigated the efficacy of different camera trap survey designs on improving the detection probability of leopard (Panthera pardus), brown hyaena (Parahyaena brunnea), and spotted hyaena (Crocuta crocuta). I found that brown hyaena and spotted hyaena detection probability increased with a higher number of camera traps, whereas leopard detection probability did not increase with an increased number of camera traps. I further investigated the diet, prey preferences and dietary overlap of lion (Panthera leo), cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus), leopard, spotted hyaena and brown hyaena. I found that all species displayed a degree of dietary overlap, however the most notable level of competition occurred between leopards, wild dogs, and cheetahs. This iv information will assist MGR to make informed decisions about large carnivore management in the reserve. I recommend continued long-term monitoring for the establishment of trends over time, allowing for holistic management of the entire large carnivore guild. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Honiball, Terry-Lee
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Carnivores
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52139 , vital:43421
- Description: Large carnivores play a vital role in ecosystems, providing ecosystem services such as herbivore regulation. If not properly monitored, carnivores could place significant pressure on certain prey species, and in extreme cases, result in the local extinction of certain species. A lack of demographic data can indirectly threaten carnivores, as policies and management decisions based on demographic data can result in the over harvesting or unsustainable hunting of large carnivores. Furthermore, their conservation is becoming confined to small, fenced, protected areas. Whereby species are intensively managed, making demographic and ecological data a fundamental part of conservation decisions. Therefore, it is essential for conservation practitioners to understand large carnivore demography and their role, to conserve them effectively. To provide Madikwe Game Reserve with the necessary data for effective long-term monitoring and management of the large carnivore guild, I estimated the population size of the cryptic carnivores. I then investigated the efficacy of different camera trap survey designs on improving the detection probability of leopard (Panthera pardus), brown hyaena (Parahyaena brunnea), and spotted hyaena (Crocuta crocuta). I found that brown hyaena and spotted hyaena detection probability increased with a higher number of camera traps, whereas leopard detection probability did not increase with an increased number of camera traps. I further investigated the diet, prey preferences and dietary overlap of lion (Panthera leo), cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus), leopard, spotted hyaena and brown hyaena. I found that all species displayed a degree of dietary overlap, however the most notable level of competition occurred between leopards, wild dogs, and cheetahs. This iv information will assist MGR to make informed decisions about large carnivore management in the reserve. I recommend continued long-term monitoring for the establishment of trends over time, allowing for holistic management of the entire large carnivore guild. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Score driven volatility models based on skewed-t distributions
- Authors: Janse van Rensburg, Stéfan
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , GARCH Model
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52010 , vital:43425
- Description: Score driven (SD) conditional volatility models allow for rich volatility dynamics and realistic distributional assumptions. These models link the evolution of time-varying volatility to the shape of the predictive density, which often results in models that are robust against outliers. These models also allow for conditional skewness. The combination of skewness and robustness may improve in-sample fit, conditional volatility forecasts and tail-risk forecasts. Therefore, this study proposes novel SD conditional volatility models with Skewed-t distributed innovations. For some of these models, the formof skewness partially negates robustness against outliers. This result demonstrates that the formof skewness requires careful consideration in the specification of SD conditional volatility models. The study also expands upon earlier observations that the assumption of negative conditional skewness may induce a form of volatility asymmetry in SD conditional volatility models that is incompatible with the leverage effect typically observed in equity markets. A simulation experiment shows that neglected leverage, therefore, biases maximum likelihood estimates. Additionally, the study considers SD conditional volatility models that account for leverage effects and have Skewed-t distributed innovations. An empirical application to the daily Johannesburg Stock Exchange (JSE) / Financial Times Stock Exchange (FTSE) All Share Index returns demonstrates the utility of SD conditional volatility models with Skewed-t distributed innovations. Extensions of these models that account for leverage prove competitive with more traditional conditional volatility models in terms of in-sample fit and tail-risk forecasts. These results suggest that the models considered in this study are useful within the context of financial risk management. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Janse van Rensburg, Stéfan
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , GARCH Model
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52010 , vital:43425
- Description: Score driven (SD) conditional volatility models allow for rich volatility dynamics and realistic distributional assumptions. These models link the evolution of time-varying volatility to the shape of the predictive density, which often results in models that are robust against outliers. These models also allow for conditional skewness. The combination of skewness and robustness may improve in-sample fit, conditional volatility forecasts and tail-risk forecasts. Therefore, this study proposes novel SD conditional volatility models with Skewed-t distributed innovations. For some of these models, the formof skewness partially negates robustness against outliers. This result demonstrates that the formof skewness requires careful consideration in the specification of SD conditional volatility models. The study also expands upon earlier observations that the assumption of negative conditional skewness may induce a form of volatility asymmetry in SD conditional volatility models that is incompatible with the leverage effect typically observed in equity markets. A simulation experiment shows that neglected leverage, therefore, biases maximum likelihood estimates. Additionally, the study considers SD conditional volatility models that account for leverage effects and have Skewed-t distributed innovations. An empirical application to the daily Johannesburg Stock Exchange (JSE) / Financial Times Stock Exchange (FTSE) All Share Index returns demonstrates the utility of SD conditional volatility models with Skewed-t distributed innovations. Extensions of these models that account for leverage prove competitive with more traditional conditional volatility models in terms of in-sample fit and tail-risk forecasts. These results suggest that the models considered in this study are useful within the context of financial risk management. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
The feeding ecology and habitat selection of small antelopes in the Overberg Renosterveld, Western Cape
- Authors: Jansen van Vuuren, Amauréé
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fynbos ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52014 , vital:43436
- Description: Human impacts have altered natural ecosystems which required species to become resilient in order to survive the anthropogenic landscape. The study area is located in the highly fragmented Overberg area in the Western Cape of South Africa. The high degree of fragmentation of the area is as a result of the nutrient rich soils and favourable topography which makes the area highly suitable for agricultural practices. The agriculture practiced in the area is mainly grain crops and livestock farming and the remaining patches of natural vegetation consist of Fynbos and Renosterveld vegetation. The patches of Fynbos and Renosterveld vegetation acts as movement corridors to allow species movement through the anthropogenic landscape. The anthropogenic landscape requires species to be resilient and to adapt to a novel habitat which poses new threats as well as new resources. The aim of the study is to investigate the effect of landscape transformation, resulting from agricultural practices, on the feeding and behavioural dynamics of five small specialist browser species in a fragmented lowland Fynbos and Renosterveld system. The objectives were to determine the forage preferences of each of the five specialist browser species and to determine which site-specific characteristics, drive the seasonal habitat use of the five specialist browser species. The five specialist browser species were bushbuck (Tragelaphus sylvaticus), Cape grysbok (Rhaphicerus melanotis), common duiker (Sylvicapra grimmia), grey rhebok (Pelea capreolus) and steenbok (Rhaphicerus campestris). To determine the dietary selection of the five specialist browser species we collected dung samples and performed a histological analysis on the dung samples. To determine the habitat use of the five specialist browser species we used an occupancy analysis framework on camera trap data collected on each of the species. Some species appeared more dependent on the food resources from the anthropogenic landscape and spent more time in the crops but required close by cover of natural vegetation. Others appeared more dependent on the remaining pockets of natural vegetation for food resources and spent more time in the natural vegetation. These species would occasionally move into the crops to utilise the food resources. Both the anthropogenic as well as the natural landscape contributed to the diets of all of the species. These species have been resilient to changes in the landscape and appear to be benefiting from the resources presented in the novel landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Jansen van Vuuren, Amauréé
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fynbos ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52014 , vital:43436
- Description: Human impacts have altered natural ecosystems which required species to become resilient in order to survive the anthropogenic landscape. The study area is located in the highly fragmented Overberg area in the Western Cape of South Africa. The high degree of fragmentation of the area is as a result of the nutrient rich soils and favourable topography which makes the area highly suitable for agricultural practices. The agriculture practiced in the area is mainly grain crops and livestock farming and the remaining patches of natural vegetation consist of Fynbos and Renosterveld vegetation. The patches of Fynbos and Renosterveld vegetation acts as movement corridors to allow species movement through the anthropogenic landscape. The anthropogenic landscape requires species to be resilient and to adapt to a novel habitat which poses new threats as well as new resources. The aim of the study is to investigate the effect of landscape transformation, resulting from agricultural practices, on the feeding and behavioural dynamics of five small specialist browser species in a fragmented lowland Fynbos and Renosterveld system. The objectives were to determine the forage preferences of each of the five specialist browser species and to determine which site-specific characteristics, drive the seasonal habitat use of the five specialist browser species. The five specialist browser species were bushbuck (Tragelaphus sylvaticus), Cape grysbok (Rhaphicerus melanotis), common duiker (Sylvicapra grimmia), grey rhebok (Pelea capreolus) and steenbok (Rhaphicerus campestris). To determine the dietary selection of the five specialist browser species we collected dung samples and performed a histological analysis on the dung samples. To determine the habitat use of the five specialist browser species we used an occupancy analysis framework on camera trap data collected on each of the species. Some species appeared more dependent on the food resources from the anthropogenic landscape and spent more time in the crops but required close by cover of natural vegetation. Others appeared more dependent on the remaining pockets of natural vegetation for food resources and spent more time in the natural vegetation. These species would occasionally move into the crops to utilise the food resources. Both the anthropogenic as well as the natural landscape contributed to the diets of all of the species. These species have been resilient to changes in the landscape and appear to be benefiting from the resources presented in the novel landscape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
A theoretical study of alkoxyl radical and radical cation mediated cyclisation reactions in unsaturated alkanols
- Authors: Lee, Peter Mattison Clarke
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Density functionals
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52130 , vital:43430
- Description: A large part of this computational study focussed on selectivity patterns for 4-penten- 1-oxyl radical 1,5- and 1,6-cyclisations and for those of analogous 5-hexenyl, 4- penten-1-aminyl, 4-penten-1-iminyl and 3-phenylpropan-1-oxyl radicals. The study furthermore included cyclisation reactions of the radical cations of 4-penten-1-ol and 3-phenylpropan-1-ol. Calculations were performed for all applicable species involved in the two cyclisation modes studied, i.e. 1,5- and 1,6-cyclisation. These species included radical and radical cation precursors, as well as relevant radical transition state structures and radical adducts. All cyclisation systems investigated used the Density Functional Theory (DFT) functional B3LYP with a combination of eight basis sets. Each basis set used was a progressively higher level of theory than B3LYP/6-31G* which was used as a starting point. Cyclisations for unsubstituted species, e.g. the 4-penten-1-oxyl radical 1,5- and 1,6-cyclisations, were also simulated using the ωB97X-D and ωB97X-V functionals which account for dispersive effects. The same set of eight basis sets were used with these two functionals. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Lee, Peter Mattison Clarke
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Density functionals
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52130 , vital:43430
- Description: A large part of this computational study focussed on selectivity patterns for 4-penten- 1-oxyl radical 1,5- and 1,6-cyclisations and for those of analogous 5-hexenyl, 4- penten-1-aminyl, 4-penten-1-iminyl and 3-phenylpropan-1-oxyl radicals. The study furthermore included cyclisation reactions of the radical cations of 4-penten-1-ol and 3-phenylpropan-1-ol. Calculations were performed for all applicable species involved in the two cyclisation modes studied, i.e. 1,5- and 1,6-cyclisation. These species included radical and radical cation precursors, as well as relevant radical transition state structures and radical adducts. All cyclisation systems investigated used the Density Functional Theory (DFT) functional B3LYP with a combination of eight basis sets. Each basis set used was a progressively higher level of theory than B3LYP/6-31G* which was used as a starting point. Cyclisations for unsubstituted species, e.g. the 4-penten-1-oxyl radical 1,5- and 1,6-cyclisations, were also simulated using the ωB97X-D and ωB97X-V functionals which account for dispersive effects. The same set of eight basis sets were used with these two functionals. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
A Functional Data Analysis approach to understand patterns imbedded within various data types
- Authors: Mangisa, Siphumlile
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Data mining
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52091 , vital:43426
- Description: The thesis investigates the use of the novel Functional Data Analysis (FDA) methods in tackling various data types. Strong motivation is provided for the use of interesting opportunities offered by FDA to analyse not only economic data, but generally, data from any domain. The use of these methods is illustrated using three unique self-contained case-studies from econometrics. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mangisa, Siphumlile
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Data mining
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52091 , vital:43426
- Description: The thesis investigates the use of the novel Functional Data Analysis (FDA) methods in tackling various data types. Strong motivation is provided for the use of interesting opportunities offered by FDA to analyse not only economic data, but generally, data from any domain. The use of these methods is illustrated using three unique self-contained case-studies from econometrics. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
Flash floods prediction in South African urban areas: Jukskei river catchment as case study
- Authors: Mawasha, Tshepo Sylvester
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52059 , vital:43429
- Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mawasha, Tshepo Sylvester
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52059 , vital:43429
- Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Participatory mapping of cultural ecosystem services in the Mountain Zebra National Park, South Africa
- Authors: Mpapane, Nelsiwe Pertunia
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Nature--Effect of human beings on--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52103 , vital:43432
- Description: Cultural ecosystem services (CES) are an essential part of human well-being. CES characterize the intangible connections that people have with their surrounding environments, and act as vessels to facilitate the understanding of meaningful and respectful relationships between humans and nature, which are necessary for sustainability. However, CES render themselves as complex cultural dimensions that are difficult to connect to specific aspects of an ecosystem, or to measure and manage. Thus, a progressive approach is required for promoting effective management of CES within landscapes. This thesis endeavours to understand human─nature interactions in protected areas, the CES benefits that arise from such interactions, and the links of these to ecosystems, facilities or features within the landscape. Protected areas represent some of the last remaining intact ecological areas that support biodiversity conservation and human─nature experiences. Protected areas, such as the Mountain Zebra National Park, are therefore suitable study sites to cast light on: (a) how human─nature relationships manifest in parks, (b) which CES are experienced by visitors, (c) which landscape features are associated with CES benefits, (d) who visits the Park, and (e) how the delivery and/or accessibility of CES to visitors of the Park could be improved. My research involved qualitative and spatial elements as forms of enquiry over a period of six months of data collection. I used semi-structured interviews (n = 20) paired with a participatory mapping approach. Additionally, I performed a comparative analysis using a peer-reviewed paper that focused on the management perspectives of CES delivery, to seek out similarities and differences between management perspectives and actual visitor experiences. The findings of this study have outlined that the Mountain Zebra National Park offers significant benefits to visitors. Aesthetic, recreational, inspirational value and cultural heritage emerged as the most frequently mapped CES. The findings have also shown that CES benefits are widely distributed across the landscape, with a spatial correlation in hotspot areas. Moreover, amenities or built infrastructure such as picnic iii sites, camping areas and viewpoints within the Park, are crucial for strengthening social relationships among family and friends, as well as in aiding the delivery of CES. This study provides insights into the subjective and diverse ways that human─nature relationships translate into CES benefits. It also sheds light on the importance of adequate planning within protected areas, for the maximization of the benefits from CES to people without compromising the mandate of biodiversity conservation. This study also contributes to a growing body of evidence that documents human─nature interactions in, and non-material benefits acquired from, protected areas within South Africa. I further advocate for improved access, adequate infrastructure, awareness creation and strategies to attract the younger generation to the national parks of South Africa. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mpapane, Nelsiwe Pertunia
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Nature--Effect of human beings on--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52103 , vital:43432
- Description: Cultural ecosystem services (CES) are an essential part of human well-being. CES characterize the intangible connections that people have with their surrounding environments, and act as vessels to facilitate the understanding of meaningful and respectful relationships between humans and nature, which are necessary for sustainability. However, CES render themselves as complex cultural dimensions that are difficult to connect to specific aspects of an ecosystem, or to measure and manage. Thus, a progressive approach is required for promoting effective management of CES within landscapes. This thesis endeavours to understand human─nature interactions in protected areas, the CES benefits that arise from such interactions, and the links of these to ecosystems, facilities or features within the landscape. Protected areas represent some of the last remaining intact ecological areas that support biodiversity conservation and human─nature experiences. Protected areas, such as the Mountain Zebra National Park, are therefore suitable study sites to cast light on: (a) how human─nature relationships manifest in parks, (b) which CES are experienced by visitors, (c) which landscape features are associated with CES benefits, (d) who visits the Park, and (e) how the delivery and/or accessibility of CES to visitors of the Park could be improved. My research involved qualitative and spatial elements as forms of enquiry over a period of six months of data collection. I used semi-structured interviews (n = 20) paired with a participatory mapping approach. Additionally, I performed a comparative analysis using a peer-reviewed paper that focused on the management perspectives of CES delivery, to seek out similarities and differences between management perspectives and actual visitor experiences. The findings of this study have outlined that the Mountain Zebra National Park offers significant benefits to visitors. Aesthetic, recreational, inspirational value and cultural heritage emerged as the most frequently mapped CES. The findings have also shown that CES benefits are widely distributed across the landscape, with a spatial correlation in hotspot areas. Moreover, amenities or built infrastructure such as picnic iii sites, camping areas and viewpoints within the Park, are crucial for strengthening social relationships among family and friends, as well as in aiding the delivery of CES. This study provides insights into the subjective and diverse ways that human─nature relationships translate into CES benefits. It also sheds light on the importance of adequate planning within protected areas, for the maximization of the benefits from CES to people without compromising the mandate of biodiversity conservation. This study also contributes to a growing body of evidence that documents human─nature interactions in, and non-material benefits acquired from, protected areas within South Africa. I further advocate for improved access, adequate infrastructure, awareness creation and strategies to attract the younger generation to the national parks of South Africa. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Fish ecology and ecophysiology in an anthropogenically-altered temporarily open/closed estuary in the warm-temperate region of the Eastern Cape Province, South Africa
- Authors: Mpinga, Mfundo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fishes--Ecology--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52122 , vital:43431
- Description: Estuaries are globally recognized for their contribution to the coastal marine environment by acting as nursery grounds for numerous marine estuarine-dependent fish species. These linking ecosystems between marine and riverine environments, are ideal for these species due to the habitat diversity, nutrient and food availability, shallower and calmer environments they provide relative to the ocean. Abrupt hydrodynamic and physico-chemical changes which frequently occur in estuaries impose physiological stress and requires superior adaptability in the fish that reside within them. This is exacerbated by anthropogenic modifications to estuaries which affects their natural ecological function. The Seekoei Estuary is one of 192 temporarily open/closed estuaries (TOCEs) in South Africa and these estuaries are characterised by their periodical connection to the sea due to the formation of a mouth berm. These estuaries are the dominant type in South Africa. A lot of research has been done in these kinds of estuaries, however, it is still limited due to their vast numbers. These estuaries are popular for human settlement and this has led to mismanagement due to the lack of ecological information. Furthermore, because of their inability to continuously flush out water, temporarily open closed estuaries are more vulnerable to pollution and anthropogenic modifications. The aim of this study was to assess the small fish community in relation to their environment in the hypersaline anthropogenically-altered Seekoei Estuary, by analysing the spatio-temporal trends of physico-chemical properties, nutrient loads, phytoplankton biomass and fish community structure. In addition, histological adaptation in gills of fish that survive hypersaline water was investigated. The study found that physico-chemical properties were influenced by anthropogenic alterations, in particular adverse water abstraction, instream water obstructions and artificial breaching. Nutrient concentration was found to be influenced by the intense agricultural practices in the upper reaches. It was evident that nutrient concentration (dissolved inorganic phosphorus) coupled with high salinity and optimum temperature (15 oC - 20 oC) affected the phytoplankton biomass. This estuary’s inability to naturally breach makes it vulnerable to phytoplankton blooms. The accumulation of cohesive silt caused by low river inflow, due to water abstraction in the upper reaches, was attributed to this estuary’s prolonged mouth closure. This was exacerbated by the presence of the causeway, which acts as a barrier between the middle and lower estuary. The abundance of marine fish species in the estuary, despite its long closure, indicates that the larvae and juveniles of these species make use of overwash events and brief artificial breaching events to recruit into the estuary. The high species richness in iii sites below the causeway is indicative of the barrier effect, which prevents the migration of some species to the upper reaches. This was evident during a massive fish kill, recorded during this study, which was more severe in sites below the causeway than above it. Chloride cell hyperplasia, mucus secretion and thickening of the epithelial layer in gills of indicator fish species from this estuary was the histological adaptation, which enables these fishes to be tolerant to high salinity. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mpinga, Mfundo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fishes--Ecology--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52122 , vital:43431
- Description: Estuaries are globally recognized for their contribution to the coastal marine environment by acting as nursery grounds for numerous marine estuarine-dependent fish species. These linking ecosystems between marine and riverine environments, are ideal for these species due to the habitat diversity, nutrient and food availability, shallower and calmer environments they provide relative to the ocean. Abrupt hydrodynamic and physico-chemical changes which frequently occur in estuaries impose physiological stress and requires superior adaptability in the fish that reside within them. This is exacerbated by anthropogenic modifications to estuaries which affects their natural ecological function. The Seekoei Estuary is one of 192 temporarily open/closed estuaries (TOCEs) in South Africa and these estuaries are characterised by their periodical connection to the sea due to the formation of a mouth berm. These estuaries are the dominant type in South Africa. A lot of research has been done in these kinds of estuaries, however, it is still limited due to their vast numbers. These estuaries are popular for human settlement and this has led to mismanagement due to the lack of ecological information. Furthermore, because of their inability to continuously flush out water, temporarily open closed estuaries are more vulnerable to pollution and anthropogenic modifications. The aim of this study was to assess the small fish community in relation to their environment in the hypersaline anthropogenically-altered Seekoei Estuary, by analysing the spatio-temporal trends of physico-chemical properties, nutrient loads, phytoplankton biomass and fish community structure. In addition, histological adaptation in gills of fish that survive hypersaline water was investigated. The study found that physico-chemical properties were influenced by anthropogenic alterations, in particular adverse water abstraction, instream water obstructions and artificial breaching. Nutrient concentration was found to be influenced by the intense agricultural practices in the upper reaches. It was evident that nutrient concentration (dissolved inorganic phosphorus) coupled with high salinity and optimum temperature (15 oC - 20 oC) affected the phytoplankton biomass. This estuary’s inability to naturally breach makes it vulnerable to phytoplankton blooms. The accumulation of cohesive silt caused by low river inflow, due to water abstraction in the upper reaches, was attributed to this estuary’s prolonged mouth closure. This was exacerbated by the presence of the causeway, which acts as a barrier between the middle and lower estuary. The abundance of marine fish species in the estuary, despite its long closure, indicates that the larvae and juveniles of these species make use of overwash events and brief artificial breaching events to recruit into the estuary. The high species richness in iii sites below the causeway is indicative of the barrier effect, which prevents the migration of some species to the upper reaches. This was evident during a massive fish kill, recorded during this study, which was more severe in sites below the causeway than above it. Chloride cell hyperplasia, mucus secretion and thickening of the epithelial layer in gills of indicator fish species from this estuary was the histological adaptation, which enables these fishes to be tolerant to high salinity. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Descriptive analysis of organic farming systems and factors affecting adoption and disadoption in Zambia : a case study
- Authors: Munthali, Robert
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic farming -- Zambia
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52111 , vital:43434
- Description: The last 30 years since the early 1990s has seen the heightened promotion of organic farming as a sustainable farming option in Zambia. The main objectives of this research study were to carry out an analysis of organic farming systems in order to understand factors affecting adoption, as well as reasons why some organic farmers discontinue using the approach. The study involved four districts in Zambia: Mazabuka, Chikankata, Lusaka and Chongwe. Specifically, the research investigated challenges and limitations of organic agronomic practices, and analysed factors that influence adopters and disadopters of organic agriculture. Primary data were collected through interviews and by administering semi-structured questionnaires. The research population comprised approximately 250 farmers adopters and disadopters, with the sample size being 50 farmers chosen across four districts using systematic random sampling methods. Additionally, five observation research field trials were conducted in order to gather practical data on individual farmer’s crop management practices. Farmers adopting and maintaining organic methods reported several reasons for embracing the system, some of which are: organic farming is regenerative; it is environmentally responsible; it uses manure, believed to help build healthy soils rich in organic matter with better nutrient and moisture holding capacity; pesticides and synthetic fertilizers are not used, reducing the levels of toxic residues in organic products which ultimately promotes health. Labour constraints, pest and disease challenges and weed problems were some of the reasons for disadoption. Data showed that disadopters had lower education (48% had primary education), were older and with slightly more children. Although there were more women adopting organic agriculture compared to men, the difference was small 56% and 44% women and men respectively. Among disadopters there were more women (67%) compared to men (33%). Overall, the study results suggest that promotion of organic agriculture should be encouraged through liaison with government departments such as the Zambian Department of Agriculture to include organic agriculture when developing policies. In general, organic farmers have positive opinions concerning the benefits resulting from organic agriculture. Organic farmers should enjoy equal opportunities to conventional agriculture in the provision of extension services, input support, infrastructural development, access to financial resources to procure farm machinery, and equipment and most important of all, they should get fair prices for their organic produce and products. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Munthali, Robert
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic farming -- Zambia
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52111 , vital:43434
- Description: The last 30 years since the early 1990s has seen the heightened promotion of organic farming as a sustainable farming option in Zambia. The main objectives of this research study were to carry out an analysis of organic farming systems in order to understand factors affecting adoption, as well as reasons why some organic farmers discontinue using the approach. The study involved four districts in Zambia: Mazabuka, Chikankata, Lusaka and Chongwe. Specifically, the research investigated challenges and limitations of organic agronomic practices, and analysed factors that influence adopters and disadopters of organic agriculture. Primary data were collected through interviews and by administering semi-structured questionnaires. The research population comprised approximately 250 farmers adopters and disadopters, with the sample size being 50 farmers chosen across four districts using systematic random sampling methods. Additionally, five observation research field trials were conducted in order to gather practical data on individual farmer’s crop management practices. Farmers adopting and maintaining organic methods reported several reasons for embracing the system, some of which are: organic farming is regenerative; it is environmentally responsible; it uses manure, believed to help build healthy soils rich in organic matter with better nutrient and moisture holding capacity; pesticides and synthetic fertilizers are not used, reducing the levels of toxic residues in organic products which ultimately promotes health. Labour constraints, pest and disease challenges and weed problems were some of the reasons for disadoption. Data showed that disadopters had lower education (48% had primary education), were older and with slightly more children. Although there were more women adopting organic agriculture compared to men, the difference was small 56% and 44% women and men respectively. Among disadopters there were more women (67%) compared to men (33%). Overall, the study results suggest that promotion of organic agriculture should be encouraged through liaison with government departments such as the Zambian Department of Agriculture to include organic agriculture when developing policies. In general, organic farmers have positive opinions concerning the benefits resulting from organic agriculture. Organic farmers should enjoy equal opportunities to conventional agriculture in the provision of extension services, input support, infrastructural development, access to financial resources to procure farm machinery, and equipment and most important of all, they should get fair prices for their organic produce and products. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Impact of feeding milk once-a-day on growth and development of jersey calves
- Authors: Myburgh, Albertus Petrus
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Calves -- Feeding and feeds
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52095 , vital:43438
- Description: In conventional calf rearing systems calves are fed milk twice a day. Calves are normally housed in a calf shed, kept in individual pens or in groups. The goal should be to limit mor-talities to less than 5% from birth to 30 days. This can be achieved by reducing animal stress, controlling diseases and feeding the animals properly. The immune function can be de-pressed by inadequate nutrition which will increase susceptibility to diseases. Key objective on a dairy farm should be to rear a healthy calf until the calf reaches the optimum mating weight. Digestive disorders and respiratory diseases are the main causes of mortalities of young calves. Jersey calves at Outeniqua Research Farm are kept in movable hutches out-side, for 8 weeks and whole milk is fed only once a day. Although it is common practice to feed milk to calves twice-a-day, Jersey calves are raised with great success by feeding whole milk once-a-day, but proven data was never collected to indicate that feeding whole milk to Jersey calves does not compromise growth or development of calves. Much research was done on feeding of milk to Holstein calves, but little was done on Jersey calves. Research also shows results on feeding of milk replacer rather than whole milk. This raised the question of can whole milk be fed once-a-day successfully to Jersey calves with-out compromising growth and development and what are the advantages of feeding whole milk once-a-day to Jersey calves? , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Myburgh, Albertus Petrus
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Calves -- Feeding and feeds
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52095 , vital:43438
- Description: In conventional calf rearing systems calves are fed milk twice a day. Calves are normally housed in a calf shed, kept in individual pens or in groups. The goal should be to limit mor-talities to less than 5% from birth to 30 days. This can be achieved by reducing animal stress, controlling diseases and feeding the animals properly. The immune function can be de-pressed by inadequate nutrition which will increase susceptibility to diseases. Key objective on a dairy farm should be to rear a healthy calf until the calf reaches the optimum mating weight. Digestive disorders and respiratory diseases are the main causes of mortalities of young calves. Jersey calves at Outeniqua Research Farm are kept in movable hutches out-side, for 8 weeks and whole milk is fed only once a day. Although it is common practice to feed milk to calves twice-a-day, Jersey calves are raised with great success by feeding whole milk once-a-day, but proven data was never collected to indicate that feeding whole milk to Jersey calves does not compromise growth or development of calves. Much research was done on feeding of milk to Holstein calves, but little was done on Jersey calves. Research also shows results on feeding of milk replacer rather than whole milk. This raised the question of can whole milk be fed once-a-day successfully to Jersey calves with-out compromising growth and development and what are the advantages of feeding whole milk once-a-day to Jersey calves? , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Testing alternative Pinus species and hybrids for the South African structural pole market
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Variation in forage quality in subtropical thicket
- Nyembe, Khulisile Jacqueline
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04