List of Titles

Aspects of the water use of Cannabis sativa L. under dryland cultivation in the Eastern Cape

Authors: Zenani, Kamva Trevor Songo
Date: 2024-10-11
Subjects: Cannabis , Water consumption , Large aperture scintillometer , Cannabis Water requirements , Dry farming South Africa Eastern Cape , Evapotranspiration
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/465035 , vital:76567
Description: Cannabis spp is one of the oldest cultivated plants, with its origin in Asia. It has two species, namely C. indica and C. sativa. This research focuses on C. sativa, which is widely cultivated locally and globally. C. sativa has a wide range of uses, including industrial, medicinal, religious, and recreational. This study will be focusing on the water use of medicinal and recreational C. sativa grown under dryland conditions. In recent years, there has been a growing interest in increasing its cultivation, but there are reports of it having high water usage. The global interest has led many governments to review the laws governing this plant as it is a controlled substance in many countries. Due to its legal status, there is a dearth of knowledge about its growth and water use. It is against this backdrop that the Water Research Commission (WRC) commissioned this study into the water use of this plant. This will provide evidence-based support for the issuing of water use licenses by the Department of Water and Sanitation. The Eastern Cape and KwaZulu Natal have many small-scale legacy farmers who have been growing C. sativa illegally for decades. The findings of this research will seek to fill some of these knowledge gaps and assist legacy farmers in the cultivation of this plant. This research had four approaches, which include 1) planting the crop in a dryland location that will mimic the conditions experienced by legacy growers, 2) the collection of plant biophysical variables in the study site in order to gain a better understanding of the plant’s health, growth, progress, and to use these variables to parameterize a mechanistic eco-physiological model, 3) the installing of a large aperture scintillometer (LAS) together with a micro-meteorological station to measure the evapotranspiration (ET) and meteorological parameters over a crop cycle, 4) to use MEDRUSH evapotranspiration model to predict the ET and compare these results against that of the LAS. The results show that water provision had a significant impact on plant biophysical variables and water use. The plants received 154 mm (2 mm day-1) of rain during the crop cycle. The large aperture scintillometer recorded a total ET of 126.8 mm (1.76 mm day-1) during the same period. The MEDRUSH model (2.5 mm day-1) overestimated the LAS ET (1.79 mm day-1), and the results from the daily ET revealed that C. sativa had higher daily ET when compared to the local grass Eragrostis plana. These results confirm that at this location in the Eastern Cape, C. sativa requires regular irrigation during the growing season to grow and secure a crop. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2024
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Date Issued: 2024-10-11

Assessing the impacts of Lantana camara and opportunities for ecological restoration after its removal: does clearing facilitate both soil and native vegetation recovery?

Authors: Bolosha, Uviwe
Date: 2024-10-11
Subjects: Lantana camara , Restoration and conservation , Restoration ecology , Invasive plants , Physicochemical process , Soil seed banks , Invasion driver
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466524 , vital:76738 , DOI https://doi.org/10.21504/10962/466524
Description: Invasive alien plants (IAPs) are one of the major contributing factors to biodiversity loss, and Lantana camara is among the top ten alien invaders worldwide. Lantana camara threatens native biodiversity and human health, prevents natural succession, and has an economic and environmental impact globally. With current climate change and future predictions, these IAPs are anticipated to continue posing huge threats to ecosystem composition, structure, and function. Even though L. camara is a widespread IAP, there is still limited knowledge in South Africa on how it influences soil physicochemical properties at the species level, vegetation communities, and soil seed banks at the community level following its invasion. There is also minimal knowledge on the management and control (i.e., clearing for restoration purposes) of L. camara in South Africa, especially in the Eastern Cape province of South Africa. To address the knowledge gap, this thesis was structured into three main aspects: understanding L. camara invasion mechanisms, evaluating invasion impacts on both the aboveground and belowground communities, and invasion management. The main objectives of this thesis were (i) to examine how L. camara invasion (at a species level) affected soil physicochemical properties across different seasons, (ii) to assess how L. camara influences natural vegetation (at a community level), (iii) to examine the effects of L. camara invasion (at the community level) on belowground soil seed banks and also assess the availability of pioneer native species and IAPs in the soil seed banks, and (iv) to evaluate soil and vegetation responses following L. camara clearing in comparison to invaded and uninvaded conditions. To answer these objectives, different studies were carried out in the Eastern Cape province, South Africa, on various farms within the Albany Thicket Biome. The results (Chapter 3) show that L. camara alters and modifies some soil physical properties, such as soil infiltration rate, repellency, and soil penetration resistance, in the communities it invades. A significant decrease in soil penetration under the L. camara canopy was observed compared to soils from the edge and out position. Moreover, significantly faster infiltration rates were observed in the canopy and edge positions than in the out position. The study also observed that these modifications in soil physical properties vary depending on the season. A seasonal comparison in soil penetration showed that soil was more compact in the dry season than the wet season, and significantly faster infiltration rates were observed in summer than in the other seasons. The soil collected under the invaded sampling positions was mostly wettable (80–100%), and not strongly, severely, or extremely repellent across all the seasons. The changes in soil properties caused by L. camara could create favourable conditions for its growth and invasion. Seasonal changes in soil properties also highlight how environmental conditions, especially temperature and rainfall patterns, can affect soil physical properties. The findings in Chapter 4 observed both the negative and positive impacts of L. camara, where the species did not have negative effects on species richness, diversity, or cover of some native species growth forms (i.e., graminoids and forbs). For all species, both species richness and Shannon-Wiener (H’) were significantly higher in the L. camara invaded condition compared to the uninvaded condition. The Simpson’s (J’) and Pielou’s evenness (D’) indices, however, showed no differences between the invasion conditions. Furthermore, the effects of L. camara on vegetation cover were growth form-dependent, with differences being noted for trees and shrubs but not for graminoids and forbs. Changes in vegetation structure and composition were also noted where L. camara created favourable conditions for some species to co-occur with it, meaning that its known trait of changing soil physicochemical properties could benefit some species. Generally, the results of this study showed that the effects of L. camara on vegetation are varied and do not have a predictable pattern, so they should not be generalised. The findings (Chapter 5) also indicate that the L. camara invasion had a negative impact on seedling abundance and composition but not species diversity and richness. This is evident through the decrease in seedling abundance of forbs and graminoids in the L. camara invaded condition. Lantana camara also acted as a refuge for some plant species, mostly native forbs and grasses, including Aptenia cordifolia, Chamaesyce prostrata, Oxalis spp., and Setaria spp., as well as alien forbs such as Bidens pilosa, Plantago lanceolata, and Taraxacum officinale, suggesting L. camara does not entirely eliminate less competitive plant species but can co-exist with them. Lantana camara also displaced some native species, and this could be associated with their displacement in the standing vegetation. Moreover, the species also displaced the seed banks of some alien species, thus showing its competitive ability. Overall, L. camara invasion negatively influenced soil seed bank seedling abundance and composition of some species, but not diversity and richness. The results in Chapter 6 indicated that clearing L. camara is an effective method for reducing its population. However, our findings suggest that clearing alone may not be enough to re-establish these communities with native species. This is because the results of this study showed varied changes in soil properties and native vegetation (species richness, species diversity, percentage cover, and composition) after L. camara clearing. For example, soil moisture and soil penetration resistance showed no significant differences among the invasion conditions; only monthly variations were observed. This is an indication that seasonality influenced these properties. Significantly lower soil infiltration rates were observed in the cleared condition compared to the other conditions and were influenced by the months and the interaction of the clearing conditions and months. The water droplet penetration time showed no significant difference among the clearing conditions over the three months, and all the soil collected from the three clearing conditions was mostly wettable. Soil chemical properties showed that the L. camara invaded and cleared conditions had significantly lower soil pH compared to the uninvaded condition, and an increase in soil pH was observed after clearing L. camara. Vegetation characteristics showed that both the Shannon-Wiener index (H') and the Simpson’s index (D') were lower in the invaded and cleared conditions compared to the uninvaded condition, and significant differences were observed. A slight increase in the H' and D' indices was also observed after clearing L. camara. The mean percentage cover for trees and shrubs was significantly higher in the invaded condition than in the cleared and uninvaded conditions. However, the mean percentage cover of forbs and graminoids was similar among the invaded, cleared, and uninvaded conditions, and no significant differences were observed. When L. camara was cleared, native species recovery was observed and was more notable in the understory species. Overall, some signs of vegetation recovery were observed, although challenges such as secondary invaders and re-invasion by L. camara were noted in the cleared areas. This chapter then concluded that active restoration interventions should be incorporated during restoration to fast-track soil and vegetation recovery. The findings of this thesis will make several significant contributions to the field of biological invasions and provide baseline information that can be used in future studies. These are discussed in the various research chapters. Overall, the thesis concludes that L. camara invasion has varied impacts on native vegetation and soil, and its clearance, should be prioritised to reduce the negative impacts. However, L. camara cleared areas (by WfW in South Africa) require follow-up and monitoring at an early stage to assess vegetation and soil restoration success. In addition, active management measures after L. camara’s removal should be considered for clearing programmes to yield positive ecosystem recovery. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2024
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Date Issued: 2024-10-11

Assessing the status of the Barotse floodplain fishery and the implications of Australian redclaw crayfish Cherax quadricarinatus invasion on the fishery

Authors: Nawa, Nawa
Date: 2024-10-11
Subjects: Zambezi Floodplains , Fishery resources Zambia Barotse Flood Plain , Introduced fishes Economic aspects , Cherax quadricarinatus , Fishery management
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466803 , vital:76780 , DOI https://doi.org/10.21504/10962/466803
Description: Inland capture fisheries play an important role of supporting livelihoods of people in developing countries. Despite their significance these fisheries are often poorly monitored resulting in them being undervalued and often missing from policy and decision-making relating to food security and water use, particularly in third world countries. The Anthropocene has given rise to increased pressure on these systems, further justifying the need for monitoring activities to determine the ecosystem service provision status and the levels of existing and emerging threats to such services. This thesis focuses on the Barotse floodplain fishery of the Upper Zambezi system and the potential implications of the recent Cherax quadricarinatus invasion on the floodplain fishery. The thesis specifically assesses the current status of the fishery (Chapter 3), invasion dynamics of C. quadricarinatus (Chapter 4), economic impact of C. quadricarinatus on the fishery (Chapter 5) and fishers’ knowledge, awareness and perception of C. quadricarinatus (Chapter 6). To evaluate the current status of the fishery (Chapter 3), fisheries dependant surveys were conducted. The study revealed a multi-gear multi-species fishery with average catch rates of 5.83 kg per fisher per day and estimated annual harvest of 3123 tonnes per annum. The decline in catch rate, low mean sizes of species harvested, change in species composition, and predominant use of illegal fishing gear compared to previous surveys, suggested further overexploitation of fishery resources. The invasive C. quadricarinatus was identified as the most dominant by-catch species and more prevalent among fishers at the invasion core and in dry season. Analysis of the invasion dynamics of C. quadricarinatus (Chapter 4) involved extensive survey of the Barotse floodplain using collapsible promar traps. The study revealed significant up and down-stream spread from the 2019 range on the floodplain. Relative abundance was higher at the invasion core compared to the invasion edge while male to female sex ratio was not different between these zones, implying both sexes were acting as dispersers. Signals of environmental filtering were not detected while density dependent spatial sorting, and hydrological variation had a strong influence on C. quadricarinatus spread. To quantify economic impact C. quadricarinatus (Chapter 5) creel surveys were conducted during wet and dry season across the invasion range. The study showed that fish damage due to crayfish was limited to gillnets at the invasion core during the dry season and equated to the monetary loss of ~ US$ 21,000 per annum. In addition, gear damage and loss of time due to crayfish was experienced for various fishing gears but most prevalent at the invasion core and more so in dry season. Assessment of fishers’ awareness, knowledge and perception (Chapter 6) involved the use of social surveys administered at the invasion core. This component revealed that most of the respondents were aware of, but not knowledgeable about C. quadricarinatus. Respondents were not aware of any management information relating to C. quadricarinatus and consequently did not follow any management practices. The respondents were supportive of management interventions due to their perceived threat of C. quadricarinatus to the fishery. Age, education, and residence of respondents significantly influenced knowledge and perceptions of C. quadricarinatus. Findings from this study have important implications for the conservation of floodplain wetlands as it informs policy makers to put in place measures that address both overexploitation and aquatic invasive species dynamics to better facilitate sustainability of fisheries and conservation of biodiversity. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
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Date Issued: 2024-10-11

Assessing the vulnerability of inland fisheries to human-induced perturbation in Lake Kariba fishery, Zambia

Authors: Imikendu, Imbwae
Date: 2024-10-11
Subjects: Fisheries Kariba, Lake (Zambia and Zimbabwe) , Small-scale fisheries , Fishery policy , Biodiversity Kariba, Lake (Zambia and Zimbabwe) , Sustainable livelihood
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466725 , vital:76774 , DOI https://doi.org/10.21504/10962/466725
Description: Inland fisheries play a critical role in providing nutrition, employment, and ensuring food security among vulnerable groups in Lake Kariba. However, their value is usually undermined in developmental plans, and their contribution to a broader economic development is often undervalued. Over the past two decades, inland fisheries have stagnated. Simultaneously, there have been wide reports of increased fishing effort and declining trends in commercially valuable fish species. This has resulted into a wide socio-economic and environmental problems in various fishing communities. Lake Kariba Zambia, exemplifies this sustainability challenge, where fisheries resources and livelihoods are interlinked. A systematic peer review paper on this topic was documented, published and used for analytical work, focusing on governance and how it affects the utilization of the fisheries resources for food security and biodiversity conservation. This study had four major objectives: (i) to identify threats to fisheries’ productivity in Lake Kariba; (ii) to understand the socio-economic and environmental conditions of small-scale fisheries in Lake Kariba; (iii) to determine adaptation strategies adopted by small-scale fishers in light of the changing socio-economic and environmental conditions in Lake Kariba; (iv) to determine how management of fisheries has to change in response to the wide socio-economic and environmental challenges in the region. Using Ostrom’s framework for analysing socio-ecological systems, various socioeconomic and environmental problems faced by fishing communities in Lake Kariba were examined to devise a sustainable fisheries management plan. The study employed explorative surveys, household questionnaires, key informant interviews, focus group discussions, observations, and a review of literature to elicit secondary data. A proportional quota sampling technique was used to draw a representative sample of 300 small-scale fishers and a typology was developed using a bivariate analysis. Chi-square was used to determine fishing effort over time. Using a curve fitting estimation regression test, a trend analysis in fish production for the past thirteen years (13) years was performed. Results did not show a significant decline in fish production over the past 13 years, yet experts and the fishers reported declining trends in valuable fish species. The finding of this study provides both practical and theoretical lessons that can enhance adaptive capacity and support sustainable livelihoods in the region. A fisheries sector policy is urgently required to guide governance process and coordinate a multi-sectoral perspective to fisheries management if socio-economic progression is to be attained. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2024
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Date Issued: 2024-10-11

Assessment and mitigation of biosecurity risks associated with macroalgae inclusion in farmed abalone diets in South Africa

Authors: Mwangudza, Petronilla Masika
Date: 2024-10-11
Subjects: Biosecurity , Seaweed , Abalone culture South Africa , Abalones Feeding and feeds , Haliotis midae , High-throughput nucleotide sequencing
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466748 , vital:76775 , DOI https://doi.org/10.21504/10962/466748
Description: The provision of biosecure diets for use in intensive aquaculture conditions requires attention, to reduce the risk of introducing potential pathogens to the farmed stock. Such introductions could lead to infections and disease outbreaks. Despite the benefits associated with macroalgae inclusion in abalone diets, several microbial hazard cases have been reported in the animal feed and human food industries. This has necessitated the application of biosecurity measures on fresh macroalgae to reduce or eliminate potential hazards and the risks of pathogen transfer to abalone stock when used as a feed or feed supplement. The present thesis assessed the efficacy of different processing treatments, including heat, ultra-violet irradiation (UVC), different pH levels, salinity concentrations, and povo-iodine on the inactivation of potential macroalgaetransmitted abalone pathogens. The effect of the processed macroalgae on the growth, health and gut microbial composition of abalone were also explored and compared with abalone fed non-processed diets. The efficacy of the different processing treatments was initially assessed on pure cultures of the test pathogens, which included a bacterium (Vibrio anguillarum), an oomycete (Halioticida noduliformans) and the bacteriophage lambda. Data from the initial assessments were then used to select the most optimal treatments for further assessment on the test pathogens inoculated in a macroalgae matrix, to simulate a more natural scenario. The viability of the three test pathogens following exposure to different processing treatments was assessed using culture methods. The results indicated that a combination of three treatments; disinfection using povo-iodine solution (5000 mg/L) for 20 min, oven drying 40 ℃ for 8.0 h and UVC treatment for 10 min rendered all the test pathogens non-culturable. Growth trials were conducted to assess the effect of the biosecure macroalgae Ecklonia maxima, Ulva lacinulata and Gracilaria gracilis on the growth performance of the abalone Haliotis midae. The macroalgae were subjected to the combination of three biosecurity processing treatments and experimental diets were then formulated to incorporate the macroalgae that had been subjected to the biosecurity processing treatments as well as macroalgae that were not. Growth parameters of the abalone after a 150-day feeding trial were compared between the biosecure and non-bioseeure macroalgae dietary treatments. Overall, the lowest growth was observed in the abalone fed with the control diet (AbfeedTM S34R) compared to all the macroalgae diets. However, no significant differences in abalone weight and shell length were recorded between the dietary treatments after the 150-day growth trial with an overall mean final weight (} standard error) of 56.55 } 0.78 g and a mean final length of 66.26 } 0.344 mm (RM-ANOVA: F(18,63) = 0.706; p = 0.792; : F(18,63) = 0.941; p = 0.535 respectively). Similarly, the biosecurity process method (biosecure vs. non-biosecure) did not have an impact on abalone weights and shell length (p > 0.05). Moreover, specific growth rate, length gain and condition factor of abalone did not differ between the biosecure and nonbiosecure dietary treatments with overall means (}standard error) of 0.27 } 0.01 % bw/d, 1.79 } 0.07 mm/month and 1.13 } 0.01, respectively (p > 0.05). Dietary macroalgae are known to contribute to the gut microflora of abalone. To determine if the biosecure process influenced this community complex, a next generation sequencing (NGS) approach was used to identify and compare the bacterial communities in abalone that were fed diets containing macroalgae that had been subjected to biosecurity treatment and those that were not. The NGS approach was also used to determine the gut microbiome profile of the abalone fed with a formulated diet supplemented with fresh U. lacinulata and G. gracilis to assess the potential modulatory effect seaweeds and their associated microbiota may have on the gut microbiome of H. midae. The bacterial alpha diversity did not differ significantly across all the diets at family, genus and species levels (p > 0.05). No significant differences in the microbiome composition were detected indicating little or no dissimilarities of the bacterial communities between the diets for all the biosecure and non-biosecure macroalgae diets. A similar core microbiome was also observed in the digestive tracts of abalone fed with the biosecure and non-biosecure diets. It was concluded that the biosecure process did not influence the natural microbiota of abalone that were fed dietary ingredients that were subjected to the process. The findings of this research have contributed to understanding the production of biosecure macroalgae formulated diets without compromising their benefits to the growth and health of farmed abalone. The combined treatment used in this study can be applied in the macroalgae and the feed industry to produce biosecure feeds. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2024
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Date Issued: 2024-10-11

Becoming a [COVID] student?: assessing the impact of COVID-19 on first-year students’ experiences of higher education in the Eastern Cape, South Africa

Authors: Nebbe, Kelsey Ann
Date: 2024-10-11
Subjects: Rite of passage , COVID-19 Pandemic, 2020-2023 Influence , College freshmen South Africa Eastern Cape , Liminality , Communitas
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/466295 , vital:76715
Description: In 2020, the COVID-19 pandemic disrupted South African higher education which forced the shift to emergency distance learning to save the academic years of 2020-2022. The repercussions of this are still emerging, but current literature focuses on understanding the impact of first-year students is focused on the impact of academics caused by the emergency shift to online, the “double transition” as Nyar (2021) termed the adjustment to university and then again to the online emergency academics. There is also a niche for holistic research to be done regarding the student experience - pandemic times and elsewise. My thesis focuses on the journey of studenthood of three cohorts at a residential university in the Eastern Cape, South Africa, through the COVID-19 pandemic of 2020-2022. This research utilises ethnographic iterative mixed methods (questionnaire, interviews, focus groups and participant observation) and the theoretical lens of Rites of Passage to understand my research participant’s experiences. My findings are that due to the circumstances of an incomplete student experience of just online academics provided an continuous liminal period for first-year students of 2020-2021, with little to no opportunity for them to develop a connection to the university community. The opportunity for them to holistically become students arises at the end of the pandemic in 2022, with the restrictions lifting and the return to on-campus and in-person academic activities allowing them to have a first-year experienced that COVID-19 prohibited. , Thesis (MSocSci) -- Faculty of Humanities, Anthropology, 2024
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Date Issued: 2024-10-11

Biological control of torch cactus in South Africa: finding a suitable agent for a non-native weed with an unknown indigenous distribution

Authors: Griffith, Tamzin Camilla
Date: 2024-10-11
Subjects: Trichocereus spachianus , Invasive plants Biological control , Dactylopius , Hypogeococcus , Host specificity
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466781 , vital:76778 , DOI https://doi.org/10.21504/10962/466781
Description: Trichocereus spachianus is an invasive cactus species in South Africa and poses challenges as a target for biological control due to confusion around its taxonomy and origin. Adapted to arid environments, this cactus is of particular concern in dry savannah and Karoo biomes, where its invasion of rangelands reduces grazing capacity for both indigenous wildlife and livestock. While previous records indicate that T. spachianus is indigenous to Argentina, recent field surveys have failed to verify its presence. Determining the origin of the target weed was important in developing a biological control programme since it enables the collection of potential agents directly from native populations of the target plant. Successful biological control programmes against cactus species in South Africa have often involved utilising both new associations and oligophagous insects, made possible because of the lack of indigenous and valued cacti in the region. Lack of T. spachianus locations in the native distribution, meant direct collection of insects from the target weed was not possible. Efforts to find biological control agents were focused on new associations between closely related cacti and their oligophagous herbivores. Suitability of multiple Hypogeococcus (mealybug) entities and a cochineal species, Dactylopius confertus, were investigated for their efficacy on various South African weedy cactus species, including T. spachianus. Findings revealed that none of the Hypogeococcus entities (species or lineages) were effective biological control agents, but D. confertus demonstrated potential as a biological control agent with a relatively high fecundity and survival rate on T. spachianus. Efficacy trials indicated that D. confertus could reach population densities sufficient to cause mortality of T. spachianus plants. Limited host specificity trials revealed that D. confertus was suitably host specific for release in South Africa, provided host specificity testing was conducted on additional plants. Approval and release of D. confertus has the potential to reduce the invasiveness of this damaging cactus in a sustainable and environmentally friendly manner. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
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Date Issued: 2024-10-11

Biology and management of the fruit piercing moth Serrodes partita in citrus orchards

Authors: Mushore, Tapiwa Gift
Date: 2024-10-11
Subjects: Baculoviruses , Moths Monitoring , Pests Control , Insect traps , Citrus Diseases and pests South Africa Kat River Valley , Catapult moth
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466792 , vital:76779 , DOI https://doi.org/10.21504/10962/466792
Description: The fruit-piercing moth, Serrodes partita (Fabricius) (Lepidoptera: Erebidae), is a polyphagous, multivoltine pest of citrus. This insect has a distinct geographical separation between its larval and adult stages, each with different feeding patterns. During the larval stage, it primarily acts as a forest defoliator, feeding mostly on Jacket plum, Pappea capensis Eckl. & Zeyh. (Sapindaceae). In contrast, the adult stage of this moth feeds on both tropical and subtropical fruit, including citrus and can cause serious economic losses. The adult moth uses its sclerotised proboscis to pierce the skin of ripening or ripe fruit, from which it extracts the juice. This piercing action initiates a fermentation process within the fruit, attracting other secondary-feeding moths, commonly referred to as fruit-sucking moths. As a result of the feeding activity, the affected fruit eventually rot, drop to the ground, and become unsuitable for the market. Serrodes partita exhibits an outbreak life strategy, reoccurring every 5 to 10 years. In South Africa's Eastern Cape Province, specifically in the Upper Kat River Valley, citrus growers have expressed concerns about the impact of this moth on soft citrus (Satsumas and Clementines). This raises the possibility of a shift in the population dynamics of S. partita, where these occurrences become more frequent and less sporadic. Such a trend poses a significant threat to fruit arboriculture in the Eastern Cape region. Currently, there are limited management strategies available for managing fruit-piecing moths. The use of pesticides is not a feasible option for ripe or nearly ripe fruit, and is ineffective against the adult moth. Alternative control methods, such as orchard netting and light barriers, either come with high costs or are impractical for large-scale citrus production. Given the limited range of management options, combined with the moth's tendency for sudden outbreaks, citrus growers find themselves without effective means to manage this pest. The objective of this study was, therefore, to investigate the biology of S. partita and explore various control options to effectively manage this pest. Research focused on the biology and laboratory rearing of larval stages of S. partita. The flight behaviour, feeding patterns, and preferences of adult S. partita within citrus orchards were also explored. The aim was to elucidate key fundamental aspects, including whether the same population frequents a particular orchard, and if infestations within orchards exhibit a specific direction. Lure type and lure presentation method trials were conducted to determine the most effective lure and trap design. Seasonal monitoring of S. partita in soft citrus orchards was conducted over three years to determine its outbreak status in the Committee’s Drift area and the role of weather variables in the activity of the moth. Damage assessments were also conducted alongside monitoring to determine the level of damage inflicted by S. partita. Natural enemies associated with S. partita were explored to determine the prevalence and causes of mortality in late instars during laboratory rearing. Rearing S. partita on an artificial diet was unsuccessful despite several modifications. The moth, however, completed its entire life cycle on its natural host, P. capensis in the laboratory. The total life cycle from egg to adult took 80.7 ± 3.6 days, the larval stage lasted 52.3 ± 2.8 days, and the pupal stage lasted 25.8 ± 3.6 days at 21°C. The investigation into the biology of S. partita also brought attention to the most susceptible stages of its growth, with high mortality rates recorded among neonates and late instars. The findings of the study revealed directional patterns of moth infestations, with higher numbers observed at the orchard's periphery leading towards natural vegetation. This raises the prospect of using sacrificial rows on the edge of a citrus orchard to concentrate moth feeding damage during outbreak years. Using a mark and recapture technique, the study showed that a relatively small proportion (4.5 %) of moths tended to revisit the same orchard. The moths strongly preferred damaged fruit (85 %) over undamaged fruit. Visible damage (rotting symptoms) typically became apparent within 3 to 5 days. Satsumas had a higher number of feeding scars (2.1) than Clementines (1.08), highlighting their susceptibility. The study also established that, on average, pierced soft citrus fruit takes about four days to display symptoms of decay. Synthetic proprietary Australian lures were ineffective at attracting the moth, whereas fresh bananas proved to be a successful lure. Furthermore, the addition of both Agar and Super absorbent polymer showed promise as thickening agents to enhance the longevity of fresh bananas in traps. The effectiveness of various trap designs was compared, including the funnel trap, delta trap, bucket trap, and circular trap, in capturing fruit-feeding moths. The funnel trap performed best as it captured the most moths, followed by the delta trap, Lynfield trap and disc trap, respectively. Additionally, an electronic enhancement to the funnel trap, incorporating a zapper element, improved efficiency. However, efforts to exploit both visual and olfactory cues through the inclusion of an Ultraviolet (UV) light component did not improve its effectiveness. No extensive outbreaks were recorded during the study; however, population variations of S. partita populations were recorded. Annual trends showed two population peaks, with the first peak recorded from December to March, while the second peak was recorded from April to July. The activity of the moths also differed across different months, with the highest peaks recorded in May, while no moths were recorded from August to November. Both cultivar type and farm location did not influence the occurrence of the moth. Meanwhile cumulative weather parameters (rainfall, temperature and humidity) from the four months prior to occurrence influenced the activity of S. partita. Temperature determined the timing of the outbreak, while rainfall determined the magnitude of the outbreak. Damage assessment showed very low fruit damage by S. partita throughout the monitoring period. Varying levels of infestation by a tachinid fly, 4 % and 35 %, were recorded for 2021 and 2022, respectively. The tachinid parasitoid could not be identified at the species level. A novel baculovirus, tentatively classified as S. partita NPV (SepaNPV), was identified as the larval mortality causative agent. This study enhanced our understanding of S. partita's biology and population dynamics, providing valuable insights for developing effective management strategies against this economically impactful citrus pest. Future research should focus on refining control measures and addressing the challenges of the adult moth's elusive nature. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
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Date Issued: 2024-10-11

Burgernomics: Raw BMI vs Adjusted BMI. A comparative analysis of appropriate exchange rate valuation measures

Authors: Gumedze, Siyanda Nakiwe Nomfundo
Date: 2024-10-11
Subjects: Big Mac Index , Purchasing power parity , Foreign exchange rates , Foreign exchange market , Economic theory
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/462702 , vital:76327
Description: The Big Mac Index was developed in 1986 by The Economist magazine as a playful take on the Purchasing Power Parity theory. Its purpose is to indicate whether a currency is overpriced or undervalued in relation to the real exchange rate and whether it can be used as a reliable indicator of exchange rate predictions. There are two versions of the Big Mac Index: the raw Big Mac Index and the adjusted Big Mac Index. If appropriate, this index might be developed into an economic theory that can be applied to corporate finance, international trade, and international finance. To determine which Big Mac Index measure is a better indicator of exchange rate valuation, a comparison analysis was conducted. This study set out to determine how well the adjusted Big Mac Index performed as a gauge for exchange rate valuation. The research then compares the two Big Mac Index measures' ability to anticipate future exchange rates in order to determine which is more accurate. Data from the South African Reserve Bank and The Economist databases covering 37 nations from 2000 to 2022 were used for the analysis. Exchange rate misalignment trends were assessed globally, and the results indicated that the adjusted BMI was a more accurate measure of purchasing power. Tests of correlation revealed that there was a positive association between the real exchange rate and the Big Mac Index. Findings from a panel ARDL Model indicated that taking into consideration country-specific GDP variations and group heterogeneity can enhance the real exchange rates' ability to predict the raw BMI. The research also focused on the South African Rand to ascertain whether the Big Mac Index validates the Purchasing Power Parity theoretical framework. Using cointegration tests and graphic analysis, it was possible to find evidence for a cointegrating relationship between the real exchange rate and the Big Mac Index measures during the last 20 years. Additionally, a positive correlation between the modified Big Mac Index and terms of trade was discovered in the results, confirming the hypothesis that the Big Mac Index satisfies current account assumptions. Finally, a VEC model demonstrated that the modified BMI outperforms the raw BMI in terms of forecasting estimates. Overall, the study found that the Big Mac Index is more than a bit of fun as per its origin. The results showed that the adjusted Big Mac Index has practical applications and the potential to be considered as an economic theory. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
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Date Issued: 2024-10-11

Carbonylation of cyclohexene with carbon dioxide (CO2) using transition metals as heterogeneous and homogeneous catalysts

Authors: Sekaleli, Bafokeng Thabelo
Date: 2024-10-11
Subjects: Carbonylation , Carbon dioxide , Catalysts , Transition metals , Cyclohexene
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/464565 , vital:76522
Description: From a green chemistry perspective, carbon dioxide (CO2) emerges as an appealing C1 synthon, given its abundance in the atmosphere and cost-effectiveness. Many essential chemicals for daily life are derived from fossilized carbon sources like coal, petroleum, and natural gas. However, the by-product of these processes, CO2, poses environmental risks when excessively emitted as a greenhouse gas. Achieving a balance between carbon emissions and removal is crucial to address environmental concerns surrounding CO2. Utilizing CO2 as a C1 source in organic synthesis holds promise for mitigating this balance in the long term. Combining CO2 with other underutilized fine chemicals, such as alkanes, alkenes, and alkynes, to produce more valuable platform chemicals presents an economically viable strategy due to carbon dioxide’s abundance, low cost, and recyclability. Despite its simplicity, CO2's high thermodynamic stability and low kinetic reactivity, owing to its highly oxidized state, pose challenges to its use as a feedstock. Overcoming these hurdles requires catalysts to enhance CO2 reactivity. Our work focuses on developing and employing catalytic systems capable of activating CO2 as a C1 synthon in reactions with cyclohexene and a reducing agent to yield carboxylic acids or esters. In one approach, we have developed heterogeneous catalyst systems comprising transition metals (Au, Fe, Ni, Ru) supported on metal oxide (TiO2). Characterization techniques such as TEM, EDX, UV-Vis, BET, and XRD were used to study the properties of these materials. The catalysts were evaluated in a reaction involving cyclohexene, CO2, and H2O. In another approach, we explored the use of cyclo-tris(tetracarbonylruthenium) [Ru3(CO)12] as a homogeneous catalyst in a reaction involving cyclohexene, methanol, and CO2 in the presence of an ionic liquid, 1-Butyl-3-methylimidazolium chloride ([BMIM]+Cl-). 1H NMR and ATR-FT-IR were utilized to characterize [BMIM]+Cl-. The reaction product was characterised utilizing GC-MS. Upon seeing that Ru3(CO)12 changes color from orange to black when exposed to heat, an investigation was undertaken on the kind of transformations that the catalyst undergoes. This investigation was carried out with the hopes of finding the structures that could be resulting from Ru3(CO)12 during the reaction and their significance to it. The orange and black Ru complexes were characterized utilizing DSC, TGA, ATR-FT-IR and PXRD. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
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Date Issued: 2024-10-11

Co-creating a pedagogy of care for our hydrocommons in South Africa

Authors: Martin, Aaniyah
Date: 2024-10-11
Subjects: Teaching Social aspects , Reparations for historical injustices South Africa , Posthumanism , Creation (Literary, artistic, etc.) , Feminism and higher education , Social justice , Environmental justice
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466418 , vital:76726 , DOI https://doi.org/10.21504/10962/466418
Description: My research focuses on watery relations in a South African context. Our planet, predominantly covered by water, relies on healthy oceans to sustain life by producing oxygen. Oceans, rivers, and wetlands constitute our natural water resources, integral to the hydrological cycle, collectively forming what Neimanis (2009) terms as hydrocommons. Hydrocommons encompass the shared water bodies and resources vital for human and more-than-human inhabitants alike. Caring for our hydrocommons is imperative for the well-being of the planet and all its inhabitants. Yet, the notion of responsibility for their upkeep sparks debate, as it intertwines with concepts of justice, extensively explored in academic discourse (Bozalek & Zembylas 2023). In South Africa, historical patterns of privilege tied to skin colour significantly influence perceptions of responsibility and care. This doctoral research engages with the enduring impacts of the apartheid legacy, which continues to shape notions of belonging, especially for Black and Brown South Africans who were forcibly displaced and restricted from accessing various areas, including urban spaces and natural environments such as beaches and game reserves. My perspective stems from my background as a scientist in the conservation field for over two decades, and transitioning into an educational doctorate with an emphasis on feminist, posthumanist, and care frameworks to address environmental and social justice concerns. Furthermore, I am a Brown Creole woman who was raised as a Muslim in Camissa, South Africa. The overarching question this dissertation seeks to address is; How can reparative care pedagogies reshape the hydrocommons for Black and Brown communities in post-apartheid South Africa? In order to respond to this question, I think diffractively with theory from feminism(s), posthumanism, research-creation and Slow scholarship - all of these are predicated on relational ontologies which embrace diverse ways of knowledge production in caring and meaning-making ways (Springgay & Truman, 2018; Stengers, 2011; Taylor et al, 2020). The research question I have posed is addressed through two key methods of enquiry namely strandlooping (beach walking) and hydro-rugging (stitching and mending). While there has been some literature on walking and mending methodologies from Northern contexts, I have opted to contextualise them within a South African framework with indigenous origins. By developing such methodologies in the local context, I aim to understand their application and relevance within South Africa's diverse cultural and environmental landscape. I have deliberately incorporated indigenous perspectives and practices in order to contribute to a more holistic and nuanced exploration of watery relations through iterative and collaborative events with participants. Chapter One provides an overview of my positionality and research practice by giving voice to those who have been marginalised, silenced and erased for three decades. The 30th anniversary for our first democratic elections was celebrated on the 27th April 2024 whilst I have been finalising my manuscript. The silence and erasure persist today, even though apartheid laws and regulations are no longer in effect. This lingering silence continues to permeate our lives and linger as a haunting presence. Consequently, strandlooping and hydro-rugging emerge as methods of enquiry that foster and provide avenues for care and healing. Chapter Two shares the stories of four Brown bodies and a tidal pool each of whom have a relationship with False Bay. The chapter shows how watery stories are shared through the process of hydro-rugging at the tidal pools. Chapter Three unravels the practice of strandlooping and develops propositions or watermarks to assist other researchers with this practice in their own contexts. Chapter Four articulates hydro-rugging as a method of enquiry and elucidates how the individual hydro-rugs are stitched alongside each other to create the Mother Hydro-rug. Chapter Five introduces three experiential research-creation events with fourth year students to meander and learn from them with regards to care for our hydrocommons. Drawing on relational ways of understanding and engaging with the world, this research culminates in several key implications for reparative care pedagogies in reshaping the hydrocommons. It underscores the importance of not only acknowledging but including diverse modes of knowledge and existence, particularly within Black and Brown communities marginalised by apartheid's racial and ethnic divisions. Additionally, it highlights the significance of challenging traditional educational paradigms entrenched in colonial and apartheid legacies. By prioritising embodied, experiential, and inclusive methodologies, the doctoral thesis advocates for a pedagogical shift toward relationality and process-oriented learning. This thesis prompts a reevaluation of extractive and exploitative educational practices, advocating instead for conviviality and the exploration of relational and embodied meanings and approaches. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2024
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Date Issued: 2024-10-11

Co-crystal formation of pharmaceutical and veterinary tranquilizer molecules

Authors: Mngwengwe, Bongeka Naledi Precious
Date: 2024-10-11
Subjects: Cocrystal , Benzodiazepines , Mechanical chemistry , Midazolam , Tranquilizing drugs
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/464532 , vital:76519
Description: Midazolam, a 1,4-benzodiazepine derivative is commonly used to treat anxiety, insomnia and may be used as a sedative in anaesthesia as it has calming, anti-convulsant and muscle relaxant properties. Midazolam has a rapid onset but a short duration of action resulting in fewer adverse effects. Midazolam also has the potential to form insoluble crystalline precipitates in pharmaceutical dosage forms such as syrups and solutions, which is a challenge in formulation and process development activities. The primary goal of this research was to prepare multicomponent crystals of midazolam free base, specifically targeting interactions with coformers structurally similar to methyl paraben. Key preparation techniques included neat grinding, liquid-assisted grinding, and slow evaporation. The resulting solid forms were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and powder X-Ray Diffraction (PXRD). In addition, Single-Crystal X-Ray Diffraction (SCXRD) was used to elucidate detailed structural information on the novel multicomponent crystals formed. Successful preparation of midazolam free base from the hydrochloride salt was confirmed through FTIR, DSC, and PXRD analysis. Different co-crystals and salts of midazolam with coformers such as salicylic acid (SA), benzoic acid (BA), 3-hydroxybenzoic acid (3-HBA) and p-aminobenzoic acid (PABA) were synthesized and characterized. The structure of the single crystal obtained from a veterinary tranquilizer solution was solved and found to be a salt that had formed between midazolam free base, midazolam HCl, and methyl paraben. This finding inspired further investigation of similar multicomponent crystals of midazolam and methyl paraben analogues. This study demonstrated the effectiveness of both mechanochemical and slow evaporation methods for the preparation of multicomponent crystals. PXRD and DSC provided insights into the stability and purity of the crystals that had formed and the differences in melting points and PXRD patterns were particularly important in this regard. Differences in FTIR spectra were used to distinguish between different solid forms and to confirm the successful formation of new solid forms. Extensive searches in the Cambridge Structural Database (CSD) confirmed that the multicomponent crystals of midazolam, such as MDZ‧SA, MDZ‧BA, MDZ‧3-HBA, and MDZ‧PABA, had not previously been reported, highlighting the novelty of these findings. The research successfully isolated and characterized several novel multicomponent crystals of midazolam, demonstrating the potential of mechanochemistry and solvent evaporation techniques in the development of pharmaceutical and veterinary medicinal applications. These findings contribute to the understanding of cocrystal formation and provide a foundation for future studies in which the stability and efficacy of midazolam-based formulations can be evaluated. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
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Date Issued: 2024-10-11

Co-management and social equity at Silaka and Hluleka Nature Reserves, South Africa

Authors: Mtshintsho, Anda
Date: 2024-10-11
Subjects: Natural resources Co-management , Social equity , Benefit sharing , Protected areas Public use South Africa Eastern Cape , Indigenous peoples Attitudes
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/464834 , vital:76549
Description: Co-management of protected areas (PAs) is a desired conservation approach aimed at balancing ecological goals and livelihood needs. Central to co-management are issues related to power sharing, responsibilities and benefit sharing. However, there still remains a dominance of an ecological emphasis in PA management, with studies focusing more on ‘objective’ biodiversity indicators for measuring the effectiveness of protected areas. However, focusing only on ecological indicators addresses a narrow perspective of achieving ecological integrity and misses social dimensions that, in some cases, might be considered more important than technical considerations. Particularly, in contexts with a history of socio-physical displacement of Indigenous people and local communities (IPLC), the social dimensions of wellbeing are complexly embedded into the economic and ecological dimensions, such that ignoring these linkages might jeopardise the success of protected areas. Thus, the aim of this study was to examine the state of research and conceptual advances on social indicators of conservation success in co-managed PAs and stakeholder views and perceptions on socially just conservation in co-managed protected areas in Silaka and Hluleka Nature Reserves, South Africa. To achieve this, a scoping review, semi-structured interviews and futures workshops (using the three horizons framework) were conducted. Findings from the scoping review (chapter 2) revealed that much of the reported social monitoring indicators still rely on quantifiable metrics (i.e., economic benefits) and less on subjective and relational metrics (i.e., qualitative strength of social networks and perceptions). Unsurprisingly, many of the reviewed case studies revealed the use of participation as an indicator of evaluating co-management success. Further, the interviews and futures workshop results in chapter 3 showed that the non-accrual of key co-management expectations such as the employment of local people, benefit-sharing (material or otherwise), participation in decision-making and community development has led to heightened conflicts between the reserve management agency and local people. Consequently, the respondents did not value the co-management arrangements, citing unfulfilled promises. Broadly, the findings of this study emphasise the need for collective and collaborative efforts in developing indicators that are not only socially just but those that are context dependent and sensitive. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2024
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Date Issued: 2024-10-11

Cocrystals, salts and eutectics of anti-tuberculosis medicines

Authors: Matlapeng, Tsebang Alice
Date: 2024-10-11
Subjects: Cocrystal , Tuberculosis , 4-aminosalicylic acid , Isoniazid , Pyrazinamide , Pyrazinoic acid
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/464521 , vital:76518
Description: Tuberculosis remains as a prominent cause of death worldwide. This infectious disease is treated with first and second line drugs. However, challenges of multi drug resistant tuberculosis and adverse side effects such as depletion of essential B group vitamins in the body by first line drugs, as well as poor physicochemical properties of second line drugs persist. Cocrystallisation of anti-tubercular drugs with various coformers has therefore been used as an alternative method to improve the physicochemical properties of active pharmaceutical ingredients (API) while maintaining their efficacy. The main objective of this study was to carry out cocrystal screening of anti-tubercular API and vitamin B coformers to make drug-drug or drug-vitamin multicomponent complexes. Preparation of the multicomponent complexes was carried out by mechanochemical grinding (neat grinding (NG), liquid assisted grinding (LAG) and slow evaporation. All complexes were characterised using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and crystal structures were elucidated using single-crystal X-ray diffraction (SCXRD). The cocrystal screening resulted in the formation of various solid forms, which included cocrystals, salts and eutectic products. Two cocrystals of 4-aminosalicylic acid (PAS) were isolated and characterised. The cocrystal of PAS with isoniazid (INH) demonstrated similar characteristics for both the bulk crystalline material and milled materials. The cocrystal of PAS and pyrazinamide (PYR) prepared using mechanochemical synthesis was met with challenges, while difficulties were also encountered in obtaining suitable crystals for SCXRD analysis. The ground and recrystallised samples of the PAS and pyrazinecarboxylic acid (PCBA) showed distinct differences in their thermal behaviour, with SCXRD revealing the decomposition product phenolammonium-pyrazinecarboxylate salt ‘sans’ the CO2 moiety. Salt formation involving pyridoxine (PN) yielded a salt hydrate with PAS (PN-PAS) and an anhydrous salt with PCBA (PN-PCBA). Both salts exhibited very complex packing arrangements with equally complex thermal behaviour depending on the solvent used during preparation, and the method of preparation. Three eutectic systems involving INH with PYR, PN and pyridoxine hydrochloride (PNꞏHCl) were identified, and their phase diagrams were constructed from DSC data. The eutectic compositions obtained were 1:1 for INH:PYR, 1:1 for INH:PN and 6:4 for INH:PNꞏHCl. Finally, a total of eight multicomponent complexes were prepared using selected API and vitamin B6 components. The results presented here provide motivation for further investigation and evaluation of the pharmacochemical properties of these API. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
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Date Issued: 2024-10-11

Comparative analysis of YOLOV5 and YOLOV8 for automated fish detection and classification in underwater environments

Authors: Kuhlane, Luxolo
Date: 2024-10-11
Subjects: Artificial intelligence , Deep learning (Machine learning) , Machine learning , Neural networks (Computer science) , You Only Look Once , YOLOv5 , YOLOv8
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/464333 , vital:76502
Description: The application of traditional manual techniques for fish detection and classification faces significant challenges, primarily stemming from their labour-intensive nature and limited scalability. Automating these kinds of processes through computer vision practices and machine learning techniques has emerged as a potential solution in recent years. With the development of and increase in ease of access to new technology in recent years, the use of a deep learning object detector known as YOLO (You Only Look Once) in the detection and classification of fish has steadily become notably popular. This thesis thus explores suitable YOLO architectures for detecting and classifying fish. The YOLOv5 and YOLOv8 models were evaluated explicitly for detecting and classifying fish in underwater environments. The selection of these models was based on a literature review highlighting their success in similar applications but remains largely understudied in underwater environments. Therefore, the effectiveness of these models was evaluated through comprehensive experimentation on collected and publicly available underwater fish datasets. In collaboration with the South African Institute of Biodiversity (SAIAB), five datasets were collected and manually annotated for labels for supervised machine learning. Moreover, two publicly available datasets were sourced for comparison to the literature. Furthermore, after determining that the smallest YOLO architectures are better suited to these imbalanced datasets, hyperparameter tuning tailored the models to the characteristics of the various underwater environments used in the research. The popular DeepFish dataset was evaluated to establish a baseline and feasibility of these models in the understudied domain. The results demonstrated high detection accuracy for both YOLOv5 and YOLOv8. However, YOLOv8 outperformed YOLOv5, achieving 97.43% accuracy compared to 94.53%. After experiments on seven datasets, trends revealed YOLOv8’s enhanced generalisation accuracy due to architectural improvements, particularly in detecting smaller fish. Overall, YOLOv8 demonstrated that it is the better fish detection and classification model on diverse data. , Thesis (MSc) -- Faculty of Science, Computer Science, 2024
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Date Issued: 2024-10-11

Composition portfolio

Authors: Musambasi, Richie Andile
Date: 2024-10-11
Subjects: Composition (Music) , Ethnoscience , Oral tradition , Traditional knowledge , Marimba , Music Zimbabwe
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/466094 , vital:76684
Description: Indigenous Zimbabwean music is complex in its make up and reveals spiritual beliefs, modes of expression, communication patterns, and forms of entertainment. The goal of this composition portfolio is to create pieces that are imbued with the spirit of indigenous Zimbabwean music making as passed on from father to son. The pieces composed include thorough-composed (pre-determined) solo and ensemble frameworks using mostly marimbas based largely on Shona scales and tuning, but also adding mbira, hosho and djembe. All of this is presented within complex structural manipulations that include African and some Western elements of formal music structure. The compositions feature two interlocking parts, known as kushaura and kutsinhira (call and respond), which are traditionally played in a simultaneous manner by two or more musicians. In this portfolio, these voices are spread across a range of players where the interplay between the parts produces complex polyphonic and polyrhythmic musical relationships. The compositions explore modal changes which add excitement, variety and an extra layer of complexity to the pieces. The final artefact is presented as a multimedia submission recorded as a documentary in real time, which is a representation of the embodied making of the music, central to this project. As music was passed down through folk tales, religious gatherings, rock paintings and sources of art, the narration is the key element in expressing that knowledge dissemination is not only text bound, but also embodied and orally shared. , Thesis (MA) -- Faculty of Humanities, Music and Musicology, 2024
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Date Issued: 2024-10-11

Connecting culture and science: Utilising Oshikundu and Ombidi in biology lessons on diffusion and osmosis

Authors: Shilomboleni, Helena Ilena Ndilimeke
Date: 2024-10-11
Subjects: Ethnoscience , Traditional knowledge , Biology Study and teaching (Secondary) Namibia , Oshikundu , Osmosis , Diffusion , Contiguity (psychology)
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/463636 , vital:76427
Description: Various science curricula including that of Namibia recommend that teaching and learning should start with the knowledge and experiences of learners from their homes and communities. These experiences are the learners’ Indigenous Knowledge (IK) which should be integrated to make science accessible and relevant to learners from diverse sociocultural backgrounds. This suggests that science teachers are encouraged to integrate IK into their teaching to help learners grasp abstract concepts and construct their own understanding of phenomena. However, much literature has revealed that many teachers find it difficult to integrate IK into their science teaching. Some scholars further argue that teachers lack the pedagogical content knowledge to effectively integrate IK. I assume this could be because the science curriculum is not explicit on how IK should be integrated into science teaching. It is against this backdrop that in this study I mobilised the Indigenous technologies of making oshikundu and preserving ombidi to support Grade 10 Biology learners in talking and making sense of diffusion and osmosis. This study was underpinned by the interpretivist and Indigenous research paradigms. Within the Indigenous research paradigm, I focused on Ubuntu as a perspective. A qualitative case study was employed and conducted at a certain school in the northern part of Namibia, in the Ohangwena region. I worked with a group of 35 Grade 10 learners, two Indigenous Knowledge Custodians (KCs) who are the custodians of cultural heritage and one Biology teacher (critical friend) as participants in this study. Qualitative data were collected using a focus group interview (sharing circle), group activity, participatory observation, and learners’ journal reflections. Vygotsky’s sociocultural theory together with Ogunniyi’s Contiguity Argumentative Theory were used as lenses to analyse data. The findings of the study revealed that during the IKCs’ practical demonstrations learners were able to identify science concepts embedded in the cultural practices of making oshikundu and preserving ombidi. The findings further revealed that the practical demonstrations enhanced active participation and interactions among learners. I thus recommend that teachers should tap into IKCs’ cultural heritage by inviting them into their classrooms to make science relevant, accessible and meaningful to learners. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
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Date Issued: 2024-10-11

Context-related drivers, occurrence and human exposure to antibiotic resistant Campylobacter in selected river systems in the Eastern Cape, South Africa

Authors: Chibwe, Mary
Date: 2024-10-11
Subjects: Antibiotic resistance , Campylobacter , Health risk assessment , Drug resistance , Public health South Africa Eastern Cape , Polymerase chain reaction
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/466644 , vital:76763 , DOI https://doi.org/10.21504/10962/466644
Description: The increasing prevalence of antibiotic-resistant Campylobacter species in river systems is a growing public health concern globally. This challenge presents the need to understand the drivers influencing the occurrence of these antibiotic-resistant strains to inform effective mitigation strategies. Identifying local anthropogenic pressures/activities will enable tailored intervention and ensure that management efforts are targeted and effective in mitigating actual risks faced by local water resources. In particular, the occurrence of antibiotic-resistant Campylobacter in river systems causes concerns regarding potential human exposure. Campylobacter species are regularly implicated in both animal and human diarrhoea, and have gained recognition as one of the main causes of waterborne diseases. This study investigated context-related drivers to the presence of antibiotic-resistant Campylobacter, its occurrence, and the risk of human exposure in the Bloukrans and Swartkops rivers in the Eastern Cape, South Africa. The study utilised a questionnaire survey and focus group discussions to identify context-related sources and drivers of antibiotic-resistant bacteria and genes in the Bloukrans and Swartkops rivers. Additionally, physico-chemical analysis of water samples was done, and polymerase chain reaction (PCR) was employed to investigate occurrences of Campylobacter in both rivers, as well as the presence of virulent and antibiotic-resistant genes. Two control sites, one for each river, and a total of nine other sampling sites were selected for this study, four along the Bloukrans River and five along the Swartkops River. Water samples were collected from all eleven sites over a period of one year, covering all the seasons (winter, spring, summer and autumn). Exposure assessment was investigated by conducting propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR) to quantify the concentration of viable Campylobacter and its antibiotic-resistance genes (ARGs) in the river water. The calculated concentration of viable Campylobacter and ARGs was then used to estimate human exposure dose of antibiotic-resistant Campylobacter via unintentional ingestion during swimming in the Bloukrans or Swartkops rivers. The questionnaire surveys and focus group discussions identified the factors of socio-demographic characteristics of the study catchments, lack of knowledge regarding antibiotic resistance, inappropriate antibiotic and disposal practices as well as anthropogenic activities (improper solid waste management, discharge of poorly treated wastewater, poor animal husbandry practices, urban run-off and storm water, industrial effluent and agricultural run-off) as context-related sources and drivers contributing to the emergence and of continuing occurrence antibiotic-resistant bacteria and genes in the Bloukrans and Swartkops rivers. The results obtained in this study suggest that the physiochemical properties of the water in the Bloukrans and Swartkops rivers are conducive for Campylobacter survival. The prevalence of Campylobacter was high at sites that recorded high turbidity, low dissolved oxygen and high conductivity. This study also highlighted the widespread and continual presence of Campylobacter spp. in the Bloukrans and Swartkops rivers, which are potentially antibiotic-resistant. The prevalence of Campylobacter was 60% virulence genes were detected at 15% (cadF), 10% (htrB), 10% (clpP), 5% (ciaB) and 5% (ctdC) for water samples from the Bloukrans River. Campylobacter was detected in 58% of water samples from the Swartkops River, while cadF, htrB, ciaB, clpP and ctdB were detected at 24%, 0%, 9.5%, 14.8% and 4.8%, respectively. Of the Campylobacter-positive water samples, the virulence genes cmeA, cmeB and cmeC were detected in 20%, 65% and 10% of the water samples from Bloukrans River, respectively. Similarly, the genes cmeA, cmeB and cmeC were detected at 14.3%, 52% and 9.5%, respectively, for the Swartkops River. Tetracycline resistance genes (tetO) were detected in 70% and 76% of the water samples collected from the Bloukrans and Swartkops rivers, respectively. It was also observed that the sampling site had a significant effect on the detection of Campylobacter for both rivers (p < 0.05). The prevalence of Campylobacter was higher for sites impacted by anthropogenic activities. The results show that sampling season had no significant effect on the occurrence of Campylobacter for both rivers. The analysis through PMA-qPCR revealed that the mean concentrations of the Campylobacter 16S rRNA gene from viable cells ranged from 2.1 × 104 to 1.75 × 105 copies/ml for the Bloukrans River, and from 0 (no detection) to 1.11 × 104 copies/ml (viable concentration) for the Swartkops River. The concentration of tetO from viable cells ranged from 4.75 × 101 to 2.71 × 103 copies/ml and 115.96 to 325.12 copies/ml, for the Bloukrans and Swartkops Rivers, respectively. Similarly, the concentration of cmeB genes from viable cells ranged from 7.8 × 101 to 2.76 × 104 copies/ml for the Bloukrans River and from 1.71 × 101 to 7.39 × 103 copies/ml for the Swartkops River. We utilized the calculated concentrations of viable Campylobacter 16S rRNA genes and ARGs to estimate the human intake burden of viable Campylobacter 16S rRNA copies per one-hour of swimming to range from 9.9 × 101 – 3.7 × 106 copies/h across the two rivers. The human intake burden of Campylobacter ARGs ranged from 3.6 × 102 – 5.8 × 105 copies/h for cmeB, and 9.98 × 102 – 5.7 × 104 copies/h for tetO. This study highlighted the intricate interplay of socio-demographic characteristics in the study catchments, such as insufficient awareness of antibiotic resistance, inappropriate antibiotic disposal practices and anthropogenic activities, which all contribute to the prevalence of antibiotic-resistant Campylobacter in the Bloukrans and Swartkops rivers, emphasizing the need for targeted interventions to address these specific influences. There is a potential risk of Campylobacter infections associated with human exposure to the rivers. This work contributes towards the body of knowledge in closing the current research gap on possible human exposure to antibiotic-resistant Campylobacter, and in general, exposure to ARBs through freshwater sources. The findings have practical implications for designing targeted interventions to mitigate these risks, to enhance the overall environmental and public health management in the region. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2024
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Date Issued: 2024-10-11

Developing transformative community-university partnerships: a participatory assessment of Rhodes University community engagement monitoring and evaluation system

Authors: Nkwinti, Nosipho
Date: 2024-10-11
Subjects: Community engagement , Community and college South Africa Eastern Cape , Rhodes University , Collaboration , Social change
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/463592 , vital:76423
Description: This thesis comprehensively explores transformative community engagement (CE) in higher education, focusing on the context of collaborative community-university partnerships (CUPs) in Makhanda, South Africa. The study aimed to assess and revise the monitoring and evaluation (M&E) system of the Rhodes University Community Engagement division to foster a transformation in CUPs. The research employs an exploratory design to understand the complexities of CUPs and improve the M&E systems by generating new concepts and ideas. A variety of qualitative methods, including focus groups, interviews, and document analysis, were utilized to engage community partners, student leaders, and Rhodes University Community Engagement staff. The participatory approach to research was critical, involving stakeholders in finalizing the M&E framework to ensure it met the shared objective. Data analysis was conducted inductively, with themes emerging from the data to facilitate a bottom-up understanding of the research questions. The study found that diverse community engagement projects at Rhodes University enhanced partnerships between the university and the local community in Makhanda. Participants shared varied understandings and experiences of Community Engagement. They saw CE as crucial for bridging the university-community divide and aiding local development. Furthermore, the research identified the need for a Monitoring and Evaluation system that supports collaborative Community-University Partnerships. Participants collaboratively developed and refined this M&E system, ensuring it aligns with community needs and promotes sustained development in Makhanda. Challenges such as diverse perspectives, logistical issues in focus groups, and power dynamics were also highlighted and addressed through an inclusive and participatory approach. This research highlights the elaborate distinctions of community engagement and the importance of such partnerships in fostering sustainable societal development. The framework developed has practical implications for shaping policies, fostering inclusivity, and promoting responsive university-community engagement that is aligned with community needs. The research concludes by suggesting the value of inclusivity, communication, and a flexible adaptation of practices to maximize the benefits of such partnerships. Future research could explore the longitudinal impacts of university-community partnerships, examine the scalability of the current framework to other universities, and evaluate the long-term socio-economic outcomes of the engaged citizen program on the community. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
Full Text:
Date Issued: 2024-10-11

Double jeopardy: reflections of accessing and navigating public spaces during COVID-19 by blind and visually impaired (BVI) people in Gqeberha

Authors: Sysaar, Nicay Courtlynn
Date: 2024-10-11
Subjects: People with visual disabilities South Africa , Blind South Africa , COVID-19 Pandemic, 2020-2023 Influence , Barrier-free design , Epidemics Social aspects , Blind Social conditions
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/466306 , vital:76716
Description: Disability only exists in reference to ability, denoting that people are only disabled if considered and treated as disabled. The inherent social conditions and features of society significantly shape disability. The impact of the COVID-19 pandemic was significant in the lives of blind and visually impaired individuals (BVI) since these individuals “access the world” through tactile contact, a behaviour strongly opposed during the pandemic. Therefore, this study explored how BVI individuals struggled to access and navigate public spaces in Gqeberha and how their risk of contracting COVID-19 increased when accessing these spaces. The study was qualitative ethnographic research. It was conducted in Gqeberha and embedded within a non-governmental organisation (NGO). A heterogeneous purposive sampling method was used to recruit ten BVI individuals and four trainers. Data was generated through semi-structured interviews and participant observation and analysed thematically. The study's key findings demonstrate that the COVID-19 countermeasures implicated the lives of BVI individuals, as some felt the need to avoid public spaces not by choice but by obligation to protect themselves from the possible risk of infection. The research findings reveal the barriers encountered through social encounters, physical navigation of the built environment, and information access, thus making the social, digital, and physical spheres inaccessible. COVID-19 exacerbated these barriers while simultaneously revealing the perpetual debilitating barriers in the lives of BVI people before the pandemic, during the pandemic, and presently. The recommendations explored the implementation of awareness-based programmes, integration and inclusion in physical spheres, and inclusionary disaster communication during disasters. Ultimately, as a society, we have a lot to do to achieve accessibility and, fundamentally, social integration. It is recommended that when developing health safety policies in times of crisis, it is crucial to consider populations with unique challenges rather than having a blasé approach. , Thesis (MSocSci) -- Faculty of Humanities, Anthropology, 2024
Full Text:
Date Issued: 2024-10-11

Showing items 81 - 100 of 18664

Aspects of the water use of Cannabis sativa L. under dryland cultivation in the Eastern Cape

Assessing the impacts of Lantana camara and opportunities for ecological restoration after its removal: does clearing facilitate both soil and native vegetation recovery?

Assessing the status of the Barotse floodplain fishery and the implications of Australian redclaw crayfish Cherax quadricarinatus invasion on the fishery

Assessing the vulnerability of inland fisheries to human-induced perturbation in Lake Kariba fishery, Zambia

Assessment and mitigation of biosecurity risks associated with macroalgae inclusion in farmed abalone diets in South Africa

Becoming a [COVID] student?: assessing the impact of COVID-19 on first-year students’ experiences of higher education in the Eastern Cape, South Africa

Biological control of torch cactus in South Africa: finding a suitable agent for a non-native weed with an unknown indigenous distribution

Biology and management of the fruit piercing moth Serrodes partita in citrus orchards

Burgernomics: Raw BMI vs Adjusted BMI. A comparative analysis of appropriate exchange rate valuation measures

Carbonylation of cyclohexene with carbon dioxide (CO2) using transition metals as heterogeneous and homogeneous catalysts

Co-creating a pedagogy of care for our hydrocommons in South Africa

Co-crystal formation of pharmaceutical and veterinary tranquilizer molecules

Co-management and social equity at Silaka and Hluleka Nature Reserves, South Africa

Cocrystals, salts and eutectics of anti-tuberculosis medicines

Comparative analysis of YOLOV5 and YOLOV8 for automated fish detection and classification in underwater environments

Composition portfolio

Connecting culture and science: Utilising Oshikundu and Ombidi in biology lessons on diffusion and osmosis

Context-related drivers, occurrence and human exposure to antibiotic resistant Campylobacter in selected river systems in the Eastern Cape, South Africa

Developing transformative community-university partnerships: a participatory assessment of Rhodes University community engagement monitoring and evaluation system

Double jeopardy: reflections of accessing and navigating public spaces during COVID-19 by blind and visually impaired (BVI) people in Gqeberha