Fucoidans from South African brown seaweeds: establishing the link between their structure and biological properties (anti-diabetic and anti-cancer activities)
- Authors: Mabate, Blessing
- Date: 2022-10-14
- Subjects: Fucoidan , Diabetes Treatment , Cancer Treatment , Brown algae
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365677 , vital:65775 , DOI https://doi.org/10.21504/10962/365677
- Description: Type 2 diabetes mellitus (T2DM) and cancer are major non-communicable diseases causing a heavy morbidity-mortality and economic burden globally. The therapeutic efforts in managing these diseases are primarily chemotherapeutic and are associated with demerits, including side effects and toxicity, limiting the prescribed amounts. These dosage limits may cause drug resistance, another major challenge in maintaining quality global health. The pursuit of novel natural bioproducts is a reasonable strategy to add to the arsenal against T2DM and cancer. Fucoidans, sulphated fucose polysaccharides abundant in brown seaweeds, have recently become popular for their biological activities, including anti-diabetic and anti-cancer properties. However, endemic South African brown seaweeds have not been adequately explored. Therefore, this study sought to characterise fucoidans extracted from South African brown seaweeds and elucidate their structure to their biological activities. Also, this study highlighted carbohydrate and glucose metabolism as major target processes in the control efforts of T2DM and cancer using fucoidans. Harvested brown seaweeds were identified as Ecklonia radiata and Sargassum elegans. E. maxima was kindly donated by KelpX. The fucoidans were then extracted using hot water, EDTA assisted, and acid extraction protocols. The integrity of the extracted fucoidan was confirmed through structural analysis using FTIR, NMR and TGA. The fucoidan extracts were then chemically characterised to determine their carbohydrate and monosaccharide composition and sulphate content. The characterised fucoidans were profiled for inhibiting the major amylolytic enzymes, namely α-amylase and α-glucosidase. The mode of inhibition by fucoidans and synergy experiments with the commercial anti-diabetic drug acarbose were also investigated. Furthermore, the fucoidans were screened for potential anti-cancer activities on the human colorectal HCT116 cancer cell line. The cytotoxicity of fucoidans was quantified using the resazurin assay. The effect of fucoidan on HCT116 cell adhesion on the tissue culture plastic was also investigated using the crystal violet-based cell adhesion assay. In addition, cancer antimigration properties of fucoidans were also investigated using 2D wound healing and 3D spheroid-based assays. Furthermore, the long-term survival of HCT116 cells was investigated through the clonogenic assay after treatment with fucoidans. Lastly, glucose uptake and lactate export assays revealed the influence of fucoidan on glucose uptake and the glycolytic flux of HCT116 cells. Fucoidans were successfully extracted with a yield between 2.2% and 14.2% on a dry weight basis. EDTA extracts produced the highest yields than the water and the acid extracts. Ecklonia spp. fucoidans displayed the highest total carbohydrate content, with glucose and galactose being the major monosaccharides. S. elegans and commercial Fucus vesiculosus had lower carbohydrate contents but contained more sulphates than the Ecklonia spp. fucoidans. Furthermore, the extracted fucoidan contained little to no contaminants, including proteins, phenolics and uronic acids. In addition, the extracted fucoidans were determined to be >100 kDa through ultracentrifugation. Mass spectrometry also detected the most abundant peak for all fucoidans to be around 700 Da (m/z). Extracted fucoidans inhibited the activity of α-glucosidase more strongly than the commercial anti-diabetic agent acarbose but were inactive on α-amylase. Fucoidans were also shown to be mixed inhibitors of α-glucosidase. Compellingly, fucoidans synergistically inhibited α-glucosidase in combination with the anti-diabetic agent acarbose, highlighting prospects for combination therapy. Finally, fucoidans demonstrated some anti-proliferative characteristics on HCT116 cancer cells by inhibiting their ability to adhere to the tissue culture plate matrix. Furthermore, some fucoidan extracts inhibited the migration of HCT116 cancer cells from 3D spheroids. Some of our fucoidan extracts also inhibited HCT116 colony formation, demonstrating inhibition of long-term cell survival. The E. maxima water extract also inhibited glucose uptake by HCT116 cells, thereby influencing the glycolytic flux. In conclusion, biologically active fucoidans were successfully extracted from South African brown seaweeds. These fucoidans demonstrated anti-diabetic and anti-cancer properties, revealing their relevance as potential drugs for these diseases. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
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- Date Issued: 2022-10-14
The role of angling-guides in promoting pro-environmental catch-and-release attitudes and behaviours in the recreational angling community
- Authors: Farthing, Matthew William
- Date: 2022-04-08
- Subjects: Fishing , Fishing Catch effort , Fishing guides , Fishers , Human behavior , Role models
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294583 , vital:57235 , DOI 10.21504/10962/294585
- Description: Angling-guides are respected as opinion leaders of the recreational angling community, but nothing is known of their influence on angler behaviour. Given their social-standing, angling-guides may be perceived as role-models by angling-clients – thereby promoting the adoption of best and/or poor catch-and-release (C&R) practices, depending on their individual knowledge, attitudes and behaviour. It is critical to understand their potential influence, their knowledge and their behaviours to inform effective intervention strategies which could exploit their extensive networking potential. The aim of this thesis was to better understand the potential utility of angling-guides in efforts to improve angler behaviour. Firstly, this was done by investigating whether angling-guides are perceived as role-models by angling-clients (Chapter 2). Secondly, it was done by assessing the current level of knowledge, attitudes and behaviours of angling-guides from around the world (Chapter 3). Thirdly, it was done by exploring the relationship between angling-guide knowledge, attitudes, intentions and actual behaviour in a case-study of guided-angling trips (Chapter 4). Lastly, it was done by exploring intervention frameworks and incorporating insights into potential strategies for promoting pro-environmental angling behaviours to angling-guides (Chapter 5). To understand if angling-guides are perceived as role-models by the recreational angling community (Chapter 2), a digital survey was designed to assess previous angling-clients’ attitudes towards angling-guides serving the three role-model functions proposed in the Motivational Theory of Role-Modelling, namely as Behavioural models, Representations of the Possible and Inspiration. Of the 492 angling-clients (27 countries), most agreed that angling-guides were competent, skilled, and worth emulating (91.1%), suggesting they are perceived as Behavioural Models. Less agreed that angling-guides were Inspirational or Representations of the Possible (54.8%), suggesting they are less likely to motivate anglers to adopt and/or pursue new goals. As Behavioural Models, angling-guide C&R practices are likely to be emulated, which is of both utility and concern to managers. As angling-guides are likely to be emulated, a digital survey was designed to assess their knowledge, attitudes and behaviours (particularly C&R best-practices) (Chapter 3). Of the 342 angling-guides (47 countries), few had accredited training (9.4%). However, most were deemed “knowledgeable of best-practices” (69.0%), but pervasive misconceptions of key C&R best-practices were observed. Attitudes towards best-practices were generally pro-environmental, and those deemed knowledgeable had significantly more pro-environmental attitudes (p = 0.003). Most angling-guides had pro-environmental attitudes towards their environmental responsibilities (87.1 - 89.5%), but these broad attitudes cannot predict specific pro-environmental behaviours during guided-angling trips where angler satisfaction is often at odds with best-practice. Angling-client satisfaction has important financial implications for angling-guides, and even those with pro-environmental intentions may struggle to adhere to C&R best-practices with inherent sacrifices for the angling-client’s enjoyment. Observation of behaviour in context is critical for understanding the behaviour to be changed. To explore the relationship between angling-guide knowledge, intentions and actual behaviour (Chapter 4), five angling-guides were observed (and filmed) interacting with groups of angling-clients during their guided-angling trips over a 30 day period. Five angling behaviours of interest were identified, and a survey focussed on these behaviours was disseminated (18 months later) to the five angling-guides previously observed to assess their knowledge, attitudes, reported behaviours and perceptions of the norm. Generally the subjects’ reported behaviours aligned well with their knowledge of best-practice, but their actual behaviour was not well aligned (24.4%). Instead, their actual behaviour aligned better with their perceptions of the norm (80.9%), which was generally a “worse” practice than what they reported. Angling-guides appeared to favour client-satisfaction over pro-environmental behaviour. Gaps between angling-guides’ knowledge of best-practice and their actual behaviour indicate that there may be obscure and complex barriers to pro-environmental angling-guide behaviour. Many barriers are seemingly impossible to overcome, such as economic limitations and financial disincentives. These barriers may limit the efficacy of traditional knowledge-attitude-behaviour (KAB) change interventions. The strong alignment of angling-guide behaviour with social norms, and the strong community orientation of recreational angling suggests that the Community-Based Social Marketing (CBSM) approach may be a more effective framework for interventions that aim to promote pro-environmental catch-and-release behaviours at angling-guide level. The CBSM approach allows interventionists to leverage a larger suite of cognitive biases than KAB approaches, provided that sufficient understanding of the context, barriers and benefits for a given segment of the angling-guide community (likely defined by style-of-participation) are obtained. Furthermore, the success of the CBSM approach will depend on the ability of interventionists to effectively recruit and incentivise disjunct and isolated communities of angling-guides to participate in training and workshops in order to achieve the important in-person contact on which the CBSM approach depends. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
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- Date Issued: 2022-04-08
Socio-historical analysis of organisational change: a case study of Zimbabwe posts (Zimpost), 2010–2020
- Authors: Kambarami-Zengeni, Faith Chipo
- Date: 2022-10-14
- Subjects: Organizational change Zimbabwe , Fordism , Industrial management , Taylor, Frederick Winslow, 1856-1915 , Industrial relations , Postal service Management
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327920 , vital:61170 , DOI 10.21504/10962/327920
- Description: Postal organisations play an important role in the provision of basic communication services. In Zimbabwe, post offices have a large physical distribution network of over 240 post offices country-wide to make communication services accessible to the populace. However, e-substitution has threatened mail business significantly. Postal operators globally are experiencing declining mail volumes in the face of advanced information and communication technologies. The overall goal of this thesis was to undertake a socio-historical analysis of organisational change at ZimPost using Taylorism, Fordism and post-Fordism as broad ideal types to explain how industry evolves in different phases of capitalism. National politics and economics play an integral role in how Taylorism, Fordism and post-Fordism assumed at ZimPost. Studies on these broad organising types have mainly focused on private sector organisations. However, this thesis argues that these analytical paradigms are also valid in public sector organisations, but they will unfold differently given the context in which change is experienced. Using a qualitative approach, the study established that the 1980s and 1990s can best be described as the ‘golden years’ of postal services in Zimbabwe, characterised by mass production and mass consumption of postal products and services. At that time the Posts and Telecommunications Corporation enjoyed a monopoly of postal services in the country. The stable market share, competitive salaries for postal workers, increased unionisation and a fairly stable economy enabled a Fordist regime of accumulation to develop. The cycle broke down when the mode of regulation was weakened by national economic and political changes towards the late 1990s. PTC started to experience a decline in the consumption of postal products. The decline was also attributed to increased competition from smaller private courier operators that could provide specialised services to a market with changing needs. With increased competition, the advancement of information, and communication technologies, mail volumes dwindled. This period can best be described as the crisis of Fordism at ZimPost. In the year 2000, the government unbundled the posts and telecommunications corporation to create four companies including Zimbabwe Posts. This was perceived as one of the most radical organisational changes in the history of postal services in Zimbabwe. More organisational changes took place at ZimPost that can best be described as characteristics of post-Fordism. These changes were attempts by ZimPost to remain relevant in light of the economic, political and technological changes taking place in the country. The postal operator introduced customised products in the form of agency services, supported by increased use of information and communication technologies in the post office. Organisational changes at ZimPost were shaped mainly by the economic and political environment in which they took place. Organisational change is complex, changes do not follow a linear pattern, they are processual. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2022
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- Date Issued: 2022-10-14
Systematics of the Afrotropical Chalcididae (Hymenoptera: Chalcidoidea)
- Authors: Faure, Sariana
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192808 , vital:45266
- Description: Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
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- Date Issued: 2021-10-29
Mitigating salt accumulation in recycled brewery effluent through the integration of water treatment, agriculture and aquaculture
- Authors: Mabasa, Nyiko Charity
- Date: 2021-10-29
- Subjects: Brewery waste South Africa Eastern Cape , Recycling (Waste, etc.) South Africa Eastern Cape , Water reuse South Africa Eastern Cape , Irrigation South Africa Eastern Cape , Sewage Purification Anaerobic treatment , Constructed wetlands , Aquaculture
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191126 , vital:45063 , 10.21504/10962/191126
- Description: Water scarcity in South Africa, and globally, presents challenges for industries. It is imperative to develop responsible water use, such as recycling and reusing wastewater from food processing industries such as breweries. The Ibhayi Brewery (SAB Ltd) employs a combination of sustainable treatment processes that include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW) to treat brewery effluent on an experimental scale. The constituent concentrations of these experimentally treated effluents are within the ranges prescribed by local regulations to allow for potential downstream use in agriculture and aquaculture. However, the sodium content in this treated effluent, which originates from upstream cleaning agents and pH control at the onsite effluent treatment facility, is a constraint to the downstream use of brewery effluent. This study addresses the salt problem, by investigating the potential of either reducing/eliminating salt addition at source, or developing alternative techniques for downstream agriculture to mitigate the effects of salt accumulation caused by irrigation with brewery effluent. Four salt-tolerant test crops; Swiss chard (Beta vulgaris), saltbush (Atriplex nummularia), Salicornia meyeriana and sorghum (Sorghum bicolor), grew efficiently in brewery effluent irrigated soils but did not stop sodium accumulation in the growth medium. Swiss chard had the best growth with a wet biomass accumulation of 8,173 g m-2, due to the plant’s ability to tolerate saline conditions and continuous cropping. Crop rotation, to limit effects of nutrient depletion in soil, had no significant effect on plant growth suggesting soils were adequately able to provide micro-nutrients in the short-term. Prolonged irrigation with brewery effluent can lead to sodium accumulation in the soil, which was successfully controlled through the addition of soil amendments (gypsum and Trichoderma cultures). These reduced soil sodium from a potentially limiting level of 1,398 mg L-1 to the acceptable levels of 240 mg L-1 and 353 mg L-1 respectively, mainly through leaching. However only Trichoderma improved Swiss chard production to 11,238 g m-2. While crop rotation in this work did not contribute to mitigating the problem of salt accumulation, soil amended with Trichoderma appears to be a potential solution when brewery effluent is reused in agriculture. In an alternative to soil cultivation, CWs were trialled with no significant differences in the sodium concentration of brewery effluent treated along a 15 m lateral flow CW, which could be attributed to evapotranspiration. This was notably accompanied by a desirable 95.21% decrease in ammonia from inlet to outlet resulting in significant improvement in water quality for reuse in aquaculture where ammonia levels are important limiting constraints. While CWs remain a suitable brewery effluent treatment solution, this technology requires additional modelling and optimisation in order to mitigate the problem of salt accumulation in the reuse of treated brewery effluent in agriculture and aquaculture. This research demonstrates the baseline information for such modelling and optimisation. African catfish (Clarias gariepinus) grew in CW treated brewery effluent; however, this growth was moderate at 0.92% bw day-1, whereas Mozambique tilapia (Oreochromis mossambicus) were shown to be unsuited to growth in this system and lost weight with an average specific growth rate (SGR) of -0.98% bw day-1; and both fish species presenting with health related concerns. Hardy fish species such as African catfish can be cultured in brewery effluent, but with risk involved. This was a preliminary study to develop parameters for future dimensional analysis modelling to allow optimisation of the CW, based on nutrient removal rates obtained which will allow for improved downstream aquaculture by reducing or eliminating risks presented in this study. This work has also contributed to a foundation for the development of guidelines that use a risk-based approach for water use in aquaculture. Alternatives to the current in place cleaning agents were considered to mitigate the effects of salt accumulation. Sodium is introduced into the effluent via the use of sodium hydroxide and sodium chlorite for cleaning and disinfection in the brewery, as well as through effluent pH adjustment in the AD plant. The widespread use of outdated legacy cleaning systems and pH adjustment regimes is entrenched in the brewery standard operating procedures (SOP). A cost-benefit analysis (CBA) demonstrated that a change of cleaning and disinfecting regimes to hydrogen peroxide in the brewery, and magnesium hydroxide pH adjustment in the effluent treatment plant addresses the sodium issue upstream in the brewery practically eliminating sodium from the effluent. In addition, a life cycle analysis (LCA) was carried out to assess the environmental impacts associated with the alternative cleaning and pH adjustment scenarios. The LCA showed that electricity consumption during use phase of the chemicals for respective purposes, as well as their production activities were major contributors to the significant environmental impact categories that were assessed. The cleaning scenario employing the use of hydrogen peroxide for both cleaning and disinfection was found to be the most environmentally sustainable. This was attributed to the reduced number of chemicals used compared to the other cleaning scenarios. Dolomitic lime was the pH adjustment alternative with the lowest average environmental impact; but, however, had a higher impact on freshwater eutrophication which is of major concern if the effluent will be reused for irrigation. Magnesium hydroxide was therefore considered to be the better option as a sodium hydroxide alternative for pH adjustment. This mitigates salt accumulation, making treated brewery effluent suitable for reuse in high value downstream agriculture and aquaculture, while employing more environmentally sustainable technologies. Notably, this converts brewery effluent from a financial liability to Ibhayi Brewery, into a product containing water and nutrients that generate income, improve food security, and can create employment in downstream agriculture and aquaculture in a sustainable manner. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
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- Date Issued: 2021-10-29
Integration of dual metallophthalocyanine catalysis and green energy for sustainable oxidative removal of endocrine disrupting compounds
- Authors: Kruid, Jan
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192820 , vital:45267
- Description: Thesis (PhD) -- Faculty of Science, Biotechnology Innovation Centre, 2021
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- Date Issued: 2021-10-29
Composition Portfolio
- Authors: Hanmer, Paul Dylan
- Date: 2022-10-14
- Subjects: Composition (Music) , String quartets Scores , Symphonies Scores , Music South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327283 , vital:61100 , DOI 10.21504/10962/327283
- Description: Extract from Introduction: “In the cover bands I worked with, I used to do what all my colleagues in these bands were doing to learn and remember repertoire; transcribe “by ear” and then rehearse with the whole band. Later, when I joined “909” [a cover band named after the “909” model of drum-box developed and built by the Japanese company, Roland] I learned to extend that skill by notating my transcriptions and then playing from these self-made keyboard parts. All the instrumentalists in that band likewise played from their own notated transcriptions and, from that time onward it became rarer for me to do any kind of performance work without a set of self-made parts to read from or refer to. I had thus reverted to performing from musical notation. Even later, when I became involved almost exclusively in improvisational music performance, I never quite abandoned the notion of having notated keyboard or piano parts to hand, as a reference or guide. Since about 1990, I have led a life that has increasingly left pop music behind and instead embraced working with improvising musicians; those who wish to explore South African folk idioms in their compositional and performance output, as well as others who have a deep love of jazz music. At the same time, I have re-entered the realm of classical music and music-making; often through writing arrangements of my own music, which would incorporate classically trained players, as well as in response to commissions to compose [for particular musicians or groups of musicians] fully notated pieces of music – such as the works in this PhD portfolio. Yet, there are many circumstantial factors that feed into my composing, and exert an influence on my creativity. A major step in this particular direction came during 2002 when composer, Michael Blake, asked me to contribute to The Bow Project. This commission brought me into close contact with the [then intact and very active] Sontonga Quartet. Several further requests for, and commissions of, new works followed on from there. Two such works constitute the major portion of the portfolio to which these reflexive commentaries refer.” , Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2022
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- Date Issued: 2022-10-14
Bioprospecting for amylases, cellulases and xylanases from ericoid associated fungi, their production and characterisation for the bio-economy
- Authors: Adeoyo, Olusegun Richard
- Date: 2018
- Subjects: Mycorrhizal fungi , Hydrolases , Ericaceae South Africa , Ericaceae Molecular aspects
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64327 , vital:28533
- Description: South Africa is one of the most productive areas for ericaceous plants with about 850 identified species in the Cape Floral Region. The Albany Centre of Endemism where all fungi used in this study were isolated from, falls within this region. Ericaceous plants interact with some fungi via an association called the ericoid mycorrhizal (ERM) association. All fungi used in this study were isolated from roots of six ericaceous plants; Erica cerinthoides, Erica demissa, Erica chamissonis, Erica glumiflora, Erica caffra and Erica nemorosa. Fungal enzymes are known to play a significant role in the food, brewing, detergent, pharmaceutical and biofuel industries. The enzyme industry is among the major sectors of the world, and additional novel sources are being explored from time to time. This study focussed on amylases (amyloglucosidase, AMG), cellulases (endoglucanase) and xylanases (endo-1,4-P-xylanase) production from ERM fungal isolates. Out of the fifty-one (51), fungal isolates screened, ChemRU330 (Leohumicola sp.), EdRU083 and EdRU002 were among the fungi that had the highest activities of all the enzymes. They were tested for the ability to produce amylases and cellulases under different pH and nutritional conditions that included: carbon sources, nitrogen sources and metal ions, at an optimum temperature of 28°C in a modified Melin-Norkrans (MMN) liquid medium. Cellulase specific activity of 3.99, 2.18 and 4.31 (U/mg protein) for isolates EdRU083, EdRU002 and ChemRU330, respectively, was produced at an optimal pH of 5.0. For amylase, ChemRU330 had the highest specific activity of 1.11 U/mg protein while EdRU083 and EdRU02 had a specific activity of 0.80 and 0.92 U/mg protein, respectively, at the same pH with corresponding biomass yield of 113, 125 and 97 mg/50 ml, respectively. Increased enzyme activities and improved mycelial biomass production were obtained in the presence of supplements such as potassium, sodium, glucose, maltose, cellobiose, tryptone and peptone, while NaFe-EDTA and cobalt inhibited enzyme activity. ChemRU330 was selected to determine the consistency and amount of amylase, cellulase and xylanase formed after several in vitro subculturing events. AMG and endo-1,4-P-xylanase were found to have the most consistent production throughout the study period. The AMG was stable at 45oC (pH 5.0), retaining approximately 65% activity over a period of 24 h. The molecular mass of AMG and endo-1,4-P-xylanase were estimated to be 101 kDa and 72 kDa, respectively. The Km and kcat were 0.38 mg/ml and 70 s-1, respectively, using soluble starch (AMG). For endo-1,4-P-xylanase, the Km and Vmax were 0.93 mg/ml and 8.54 U/ml, respectively, using beechwood xylan (endo-1,4-P-xylanase) as substrate. Additionally, crude extracts of five root endophytes with unique morphological characteristics were screened for antibacterial properties and was followed by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). L. incrustata (ChemRU330) and Chaetomium sp. extracts exhibited varying degrees of inhibition against two Gram-positive and Gram-negative bacteria. The crude extract of L. incrustata was the most effective which was found to inhibit Staphylococcus aureus (MIC: 1 mg/ml), Bacillus subtilis (MIC: 2 mg/ml) and Proteus vulgaris (MIC: 16 mg/ml). The L. incrustata displayed potential for antibacterial production and could be considered as an additional source of new antimicrobial agents in drug and food preservation. Also, the three isolates used for enzyme production were identified to genus and species levels, i.e., Leohumicola incrustata (ChemRU330), Leohumicola sp. (EdRU083) and Oidiodendron sp. (EdRU002) using both ITS and Cox1 DNA regions. The molecular analysis results indicated that these ERM mycorrhizal fungi were similar to those successfully described by some researchers in South Africa and Australia. Therefore, this study opens new opportunities for exploring ERM fungal biomolecules for the bio-economy. The promising physicochemical properties, starch and xylan hydrolysis end- products, and being non-pathogenic make AMG and endo-1,4-P-xylanase potential candidates for future applications as additives in the food industry for the production of glucose, glucose syrups, high-fructose corn syrups, and as well as the production of bioethanol. Finally, the findings of this study revealed that it is possible to produce hydrolytic enzymes from ERM fungi in vitro using chemically defined media. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
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- Date Issued: 2018
Synthesis and evaluation of novel heterocycles as potential HIV-1 enzyme inhibitors
- Authors: Ngnie Tuemgnie, Gaëlle Tatiana
- Date: 2014
- Subjects: Heterocyclic compounds , Enzyme inhibitors , Organic compounds , Green chemistry , Coumarins , HIV (Viruses) Enzymes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/194293 , vital:45440 , DOI https://doi.org/10.21504/10962/194293
- Description: This project has focussed on the synthesis and the evaluation of organic compounds as potential HIV-1 enzyme inhibitors, by making use of green chemistry (microwave assisted synthesis and click chemistry), palladium catalyzed reactions (Heck and Sonogashira coupling), Baylis Hillman methodology and aldol condensation. These compounds were synthesized in good yields and fully characterised by spectroscopic techniques. Biological assay data revealed that some of the compounds possess high inhibitory activity and their effective inhibitory concentration was as good as those of drugs in clinical use. These potential drug molecules were identified by preliminary investigations carried out by molecular modelling where a trend of their inhibitory activity against different enzymes was anticipated. Benzotriazole-AZT conjugates generated by 1,3-dipolar cycloaddition of anthranilic acid derivatives with AZT showed good inhibitory activity in silico against both HIV-1 protease (PR) and HIV-1 reverse transcriptase (RT) enzymes. Still in line with our dual action strategy, cinnamate ester-AZT conjugates were synthesized in three steps starting from benzaldehyde derivatives with a click reaction at the final step. These compounds also showed some inhibitory activity against HIV-1 RT enzyme (88%). In addition, the cinnamoyl fragment attached to AZT appeared to improve the activity of AZT against HIV-1 RT. Peptide chemistry involving carbonyl diimidazole as a coupling reagent between cinnamic acid derivatives and protected amino acids was used to prepare substituted amino acid derivatives which appeared to be very active against the integrase (IN) enzyme (88%). Commercially available coumarin was iodinated and derivatized through palladium catalyzed Heck and Sonogashira reactions with activated alkenes and a terminal alkyne respectively to afford novel coumarin derivatives in good yields. Optimization studies on the Heck reaction with regards to the phosphine ligand, the palladium catalyst and the solvent were carried out to afford novel formyl substituted cinnamate esters with nonaflyl salicylaldehyde derivatives. , Thesis (PhD) -- Faculty of Science, Chemistry, 2014
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- Date Issued: 2014
An ethnographic exploration of black lesbians rape survivors’ access to support services in Cape Town South Africa
- Authors: Wilson, Kaythrine Esther Jacqueline
- Date: 2022-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/232646 , vital:50010
- Description: Thesis (PhD) -- Faculty of Humanities, Sociology, 2022
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- Date Issued: 2022-04
Exploring aspects of Community of Inquiry (CoI) in Afrophilia learning processes for transformative education using an Afrophilic ‘Philosophy for Children’ approach: a case of Sebakwe resettlement primary schools in the Midlands Province of Zimbabwe
- Authors: Bhurekeni, John
- Date: 2023-03-29
- Subjects: Culturally relevant pedagogy Zimbabwe , Curriculum change Zimbabwe , Philosophy Study and teaching (Elementary) Zimbabwe , Critical thinking , Decolonization Zimbabwe , Technology Political aspects , Representation (Philosophy)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/366178 , vital:65840 , DOI https://doi.org/10.21504/10962/366178
- Description: This study focused on investigating and developing an Afrophilic orientation to a sociocultural approach to philosophy for children. The main aim was to foster a critical and generative approach to considering the heritage-based curriculum foundations of Zimbabwean primary schools, focusing on Sebakwe resettlement primary schools (the case study area). Afrophilia foundations in the study are regarded as “the discourses that are the medium of philosophical reflexion” (Rettova, 2004, p. 4) in each African society. As articulated in the study, such discourses include African proverbs, poems, stories, music, and folktales which are useful in the initiation of philosophical engagements with children in a community of inquiry approach. A community of inquiry is a framework that reflects a collaborative-dialogical approach to teaching and learning. Curriculum reviews in postcolonial Zimbabwe have revealed an unconscious misalignment of the Zimbabwean education system's philosophical underpinnings because it has continued to align itself with imperial British colonial philosophy, which contradicts the country's developmental needs (Presidential Commission of Inquiry into Education and Training [CIET], 1999, Zimbabwe Ministry of Primary and Secondary Education [MoPSE], 2014). The philosophical misalignment is an extension of the colonial history of Zimbabwe showing that vestiges of colonial rule still shape the education sector. This leaves the education system focusing mainly on abstracted concepts with continued marginalisation of local cultures, discourses, and knowledge. Consequently, it leaves Zimbabwe together with other postcolonial education systems with the task of dealing with the phenomenon of colonial continuity. One implication of these colonial continuities, is learner disinterest in learning, which affects the educational process negatively, affecting the learning of critical reflexive thinking, an issue which I have observed in the Sebakwe resettlement schools involved in this study where I have been teaching for 15 years. To address, this, the study sought to answer the following questions: What historical and contemporary barriers are affecting the promotion of a culture of learning in Zimbabwean resettlement primary schools, particularly as they relate to learners' underdevelopment of critical reflexive thinking skills? In addition, How can the Philosophy for Children Afrophilia curriculum intervention promote a culture of learning in Sebakwe resettlement primary schools that is oriented toward the development of critical reflexive thinking skills in children? In approaching the research questions, I applied postcolonial and decolonisation theory, sociocultural learning theory and curriculum theory aimed at transformative change, that is oriented towards achieving a more contextually oriented approach to teaching and learning, and a paradigm of ‘learning as connection’ (Lotz-Sisitka & Lupele, 2017; Shumba, 2017). This has been identified as a ‘missing’ discourse in mainstream educational quality discourses in southern Africa (Lotz-Sisitka & Lupele, 2017). Furthermore, to create space for curriculum development using multi-actor groups in a community of inquiry, I used decolonial research methodologies in the data generation process. The study is constituted as an interventionist case study, and I applied a four-stage process comprising document analysis, workshops, participant observations involving children between 8-11 years, and reflective interviews with parents, educators and children as instruments for data gathering. I also used process-based analytical tools developed in Philosophy of Children research to analyse the processes of critical reflexive thinking development that emerged from the Philosophy for Children pedagogy involving ten lessons which I facilitated, and videorecorded. Moreover, I used postcolonial and decolonial discourse analysis to provide the broader analytical insights that informed the interpretations of the lesson analysis data from the perspective of the research problem that I address across the research project. This PhD is produced as a PhD by publication, which involves publishing of papers, and orientation to, and interpretation of the papers. The main findings of this study are reported in articles that I prepared for publication, three of which have already been published (see Appendices A1, A4 and A5), and four which have been submitted for publication (A2, A3, A6, A7) with some already at an advanced stage of finalisation via review. The conceptual paper (A1) that served as the foundation for the publication journey revealed that, in addition to the weight of cultural technologies of domination, the curriculum is shaped by the paradox of a superficial interpretation of unhu/ubuntu educational philosophy. As a result, the curriculum becomes disconnected from the learners' real-world experiences. The second paper (A2), which focuses on why Zimbabwe needs the Philosophy for Children approach with a sociocultural medley, unveils Zimbabwe's complex decolonial curriculum reforms and their many contradictions and paradoxes. However, it also emerged that the approach used in this study empowers teachers, is relevant to the emerging constellation of practices in the Sebakwe resettlement, and influences power sharing beyond teacher-child relationships. The third paper (A3), based on children’s philosophy for children practice, defends the study’s decision to bring children’s heritage and cultural lens to bear on curriculum and pedagogical praxis. In essence, the article explores a synergy between philosophy for children and the Zimbabwean heritage-based educational curriculum, serving to enrich both. The fourth paper (A4) makes the case that philosophy for children could be a viable pedagogy for transformative education, and it provides evidence-based implementation of a context-based philosophy for children. According to this paper, the approach is effective in strengthening strong community relationships, instilling pride in local heritage, and advancing curriculum transformation. The fifth paper (A5) focusses on the approach's implications for teachers' roles, practices, and competencies. Six dimensions of teacher roles, practices, and competences surfaced, including the role of the teacher as a decoloniser and pedagogical innovator, among others. The sixth paper (A6), influenced by the previous papers' findings, focused on decolonisation and improving learning opportunities for children in the Sebakwe area using the philosophy for children approach. This paper's data depicts a ‘third space’ in which learners consolidate their cultural capital and curriculum content into their own meaning construction. The implication is that schools become neutral sites that improve learners' interdependence and inclusivity while also taking contextual realities into account. The findings of the seventh and final paper (A7) presented in this write-up advance the idea that a Philosophy for Children approach with a sociocultural medley influences an ethics of care by demonstrating how Afrophilia experiences influence a new path to wildlife conservation and sustainability. The study highlights that integrating Philosophy for Children and Afrophilia foundations of knowledge into the school curriculum promotes critical reflexive thinking skills, helps to address real-life problems and adds relevance to the curriculum. The study further shows that the integration of philosophy for children in the advancement of curriculum transformation in Zimbabwe is a successful formative interventionist approach in the resettlement schools that are characterised by a critical shortage of teaching and learning resources. In essence, the research opens an understanding that curriculum transformation and decolonisation are context-based and multi-actor processes, as showcased in the experiences of parents, teachers, education inspectors, and children in this study. Furthermore, this study posits that situating curriculum decolonization and transformation within unhu/ubuntu dialectical rationality and advancing diversity in reasoning necessitates deeper engagement with heritage-based curriculum and provides teachers with appropriate agency to modify and adapt their pedagogies in alignment with the learners' life world. According to the study, this emerged as a rational possible solution to the problem of curriculum decontextualisation. Curriculum decontextualisation as highlighted in the study via the problem of colonial continuity mentioned above, appears to be further influenced by the emphasis on examination assessment scores which seem to widen the gap between the adult and child worlds, as well as the gap between contextual realities and [curriculum] examination content. Overall, the study offers an approach that can deepen an unhu/ubuntu foundation for the heritage-based curriculum reform in Zimbabwe, and strengthen the learning of children in the resettlement schools, where the case was explored. Implications for further research are elaborated, as are possible implications for policy and practice. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
- Date Issued: 2023-03-29
Demand-side factors and the employment of young people: A case study of the recruitment and selection strategies of selected firms in Johannesburg
- Authors: Gabobegwe, Maoshadi Keletso Amanda
- Date: 2022-10-14
- Subjects: Unemployment South Africa , Underemployment South Africa , Unemployed youth South Africa , Labor market South Africa , Employees Recruiting South Africa , Employer attitude surveys South Africa , International Labour Organisation
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327294 , vital:61101 , DOI 10.21504/10962/327294
- Description: Unemployment is a long-standing and pressing socio-economic phenomenon that affects, markedly, both developed and developing countries. Although, in one way or another, many people are affected by unemployment, the reviewed literature concurs that youth unemployment is a critical component of the overall unemployment challenge. Indeed, the burden of unemployment is borne, tremendously, by young people, especially those who are Not in Education, Employment, or Training (NEETs). The International Labour Organisation (ILO) has declared youth unemployment a global crisis, with approximately 67,6 million unemployed young people worldwide in 2018. In South Africa, the youth unemployment rate escalated to 56.4 per cent in the second quarter of 2019. This disturbing level of unemployment among young people poses a serious threat—for as long as young people stay unemployed. Indeed, the cost of unemployment is too high, not only does it engender discontent among young people who are floundering in poverty and frustration, but it can also trigger or perpetuate all sorts of social, political, and economic effects. These effects only exacerbate the already intricate and onerous global agenda of tackling unemployment— because they give rise to other socio-economic ills (e.g., crime, among others) that also need to be addressed. Owing to this grave and perpetual challenge of unemployment, exploring and understanding the dynamics of youth unemployment continues to be of paramount importance worldwide. This thesis, in particular, seeks to investigate the factors that impede on the employment of the NEETs category, as it may be extremely difficult for them to enter the labour market— and they may lose hope of entering the labour market later in life, if they are unsuccessful while still young. Unlike graduates or other youth categories (i.e., matriculants) who have better chances in the labour market, some young people (by virtue of being ‘dropouts’, teenage moms/dads, having failed matric, among other reasons), remain the most vulnerable to unemployment. For this reason, the primary aim of this thesis is to examine the ways in which employers’ recruitment strategies advantage or disadvantage young people (NEETs). The secondary aims include: (a) examining how employers' perceptions and attitudes, regarding the NEETs youths, influence their recruitment decisions when it comes to employing young people; and (b) understanding the ways in which government strategies (devised to combat youth unemployment) influence employers’ decisions to recruit the youths’ or not. In essence, this study seeks to explore the demand-side factors in the labour market that can help us understand how employers’ recruitment decisions (or recruitment behaviour) affect the employment prospects of young people in the labour market. The focus on demand-side factors is motivated by Labour Market Segmentation (LMS) theories, which serve as the theoretical framework of this thesis. LMS theories’ significance lies in their opposition to neoclassical economics, that posit the existence of a unified labour market (which operates like all other markets), consisting of buyers and sellers in ‘free’ competition. According to neoclassical theory, the difference between workers’ employment and wages is determined by ‘individual preferences’ and investments in ‘human capital’ (skills, experience, formal education, etc.). By contrast, LMS theorists argue that labour markets are fragmented, and that differences on the demand side imply differences in compensations that are not totally determined by individual workers' human capital. Inspired by the claims of LMS theories, this study elected to explore demand-side factors by applying qualitative research methods and techniques to gather and analyse the data gathered, and to ultimately address the research objectives. In particular, non-probability sampling was used to sample 20 firms from four sectors (manufacturing, retail/hospitality, finance, transportation) in the Johannesburg (CBD) region. The respondents were all asked a series of semi-structured questions in order to yield qualitative results that would help determine the employers’ dispositions towards young people; and about the government’s strategies that address youth unemployment. The aim is to provide an in-depth, nuanced understanding of how the respondents’ dispositions influence the inclusion or exclusion of young people in the employers’ recruitment considerations. The aggregate results of the study generally indicate that—although there are innumerable factors that affect young peoples' employment prospects—young people (without skills and tertiary education or matric) are actually being employed, and are still being considered for employment by the majority of the sampled employers (predominantly from retail/hospitality firms). Only a minority of employers stated, categorically, that they do not employ young people, and do not intend to do so. Conversely, the results also reveal that the the majority of employers often recruit young people for general and entry-level jobs that are often offered on a non-standard employment basis. At face value, the employment of young people (without skills) in the majority of the sampled firms may seem to make a difference—and it probably does, for as long as young people are exposed to the world of work. However, in the 4 grand scheme of things, the kind of employment offered in these firms is also problematic, because it is, basically, transient and unsustainable. As such, the young people that occupy these jobs are most likely to find themselves back in the unemployment queues whenever the ‘part-time’ or ‘temporary’ employment contracts are terminated. These jobs are especially problematic because policies such as the National Development Plan (NDP) 2030—in line with Sustainable Development Goals—aim to reduce poverty by creating sustainable employment. Contrarily, these kinds of jobs make it hard to achieve poverty reduction, because they are inherently unsustainable and barely lift people (especially young people) from unemployment and poverty. Based on these results, it can be asserted that the proliferation of non-standard employment compromises the agenda for decent work, and it delays the already sluggish Sustainable Development goal of creating sustainable employment (among other goals). This, then, reveals that there is still a stark and long-standing need for more radical strategies that will ensure the creation of sustainable jobs—without which the unemployment crisis will be far from over. Moreover, the results further indicate that the reasons why the minority of the sampled employers do not employ young people boil down to the fact that young people usually do not have what employers look for in their potential recruits; or that young people do not have what employers believe will contribute to the growth and productivity of their firms. In essence, employers will never employ any young person (or any jobseeker in general) that will be a liability than an asset in their firms. Over and above, this thesis corroborates many of the explanations—encapsulated in the growing literature—for rising unemployment, as well as the claims that unemployment is highly pronounced among young people. However, the contribution of this thesis is that it further offers a nuanced view to understanding the demand-side factors (as additional determinants) that hinder the employment of young people (especially those who make up the NEETs category). , Thesis (PhD) -- Faculty of Humanities, Sociology, 2022
- Full Text:
- Date Issued: 2022-10-14
Bioinformatics tool and web server development focusing on structural bioinformatics applications
- Authors: Nabatanzi, Margaret
- Date: 2022-10-14
- Subjects: Structural bioinformatics , Proteins Structure , Protein structure prediction , Proteins Conformation , Protein complex
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365700 , vital:65777 , DOI https://doi.org/10.21504/10962/365700
- Description: This thesis is divided into two main sections: Part 1 describes the design, and evaluation of the accuracy of a new web server – PRotein Interactive MOdeling (PRIMO-Complexes) for modeling protein complexes and biological assemblies. The second part describes the development of bioinformatics tools to predict HIV-1 drug resistance and support bioinformatics research and education. Recent technological advances have resulted in a tremendous increase in the number of sequences and protein structures deposited in the Universal Protein Resource Knowledgebase (UniProtKB) and the Protein Data Bank (PDB). However, the number of sequences has increased at a higher rate compared with the experimentally solved multimeric protein structures. This is partly due to advances in high-throughput sequencing technology. To fill this protein sequence-structure gap, computational approaches have been developed to predict protein structures from available sequences. Computational approaches include template-based and ab initio modeling with the former being the most reliable. Template-based modeling process can be achieved using either standalone software or automated modeling web servers. However, using standalone software requires familiarity with command-line interfaces as well as utilising other intermediate programs which could be daunting to novice users. To alleviate some of these problems, the modeling process has been automated, however, it still has numerous challenges. To date, only a few web servers that support multimeric protein modeling have been developed and even these provide little, if any user involvement in the process. To address some of these issues, a new web server – PRIMO-Complexes – was developed to model protein complexes and biological assemblies. The existing PRIMO web server could only model monomeric proteins. Part 1 of this thesis provides a detailed account of the development and evaluation of PRIMO-Complexes. The rationale for developing this new web server was based on the understanding that most proteins function as protein multimers and often the ligand-binding sites, and enzyme active sites are located at the protein-protein interfaces. It, therefore, necessitated developing capabilities for modeling multimeric proteins. PRIMO-Complexes web server was developed using the Waterfall system development life cycle model, is based on the Django web framework and makes use of high-performance computing resources to execute jobs. The accuracy of the algorithms embedded in PRIMO- Complexes was evaluated and the results were promising. Additionally, PRIMO-Complexes performs comparatively well in relation to other web servers that offer multimeric protein modeling. Another unique feature of PRIMO-Complexes is its interactivity. The webserver was developed with capabilities for allowing users to model multimeric proteins with an appreciable degree of control over the process. In the second part of the thesis several other bioinformatics tools are described, for example, a webserver for predicting HIV-1 drug resistance, the RUBi protein model repository, and a bioinformatics web portal for education and research resources. RUBi protein model repository stores verified theoretical models built using various modeling approaches. This enables users to easily access models to reproduce and/or further the research. This is described in chapter 5. Chapter 6 describes the design and development of the Human Immunodeficiency type 1 Resistance Predictor (HIV-1 ResPredictor), a web application that employs artificial neural networks (ANN) to predict drug resistance in patients infected with HIV-1 subtype B. The ANNs and subtype classifiers performed well making this web application potentially useful to both clinicians and researchers in this era of personalised medicine. Finally, chapter 7 describes a bioinformatics education web portal that equips students with information on how to use bioinformatics online resources. Being aware of these resources is not enough without a deeper understanding and guidance on how to apply bioinformatics methods to solve practical problems. This web portal was aimed at familiarising students with the basic terminology and approaches in structural bioinformatics. Students will potentially gain skills to conduct real-life bioinformatics research to obtain biological insights. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-10-14
Formulation of an enzyme cocktail, HoloMix, using cellulolytic and xylanolytic enzyme core-sets for effective degradation of various pre-treated hardwoods
- Authors: Malgas, Samkelo
- Date: 2018
- Subjects: Biomass , Cellulase , Hardwoods , Xylanases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/62827 , vital:28297 , DOI https://doi.org/10.21504/10962/62827
- Description: Currently, there is a growing interest in utilising hardwoods as feedstocks for bioethanol production due to the vast advantages they have over other feedstocks for fermentable sugar production. In this study, two selected hardwoods, Acacia and Populus spp., were subjected to two pre-treatment processes (Sodium chlorite delignification and Steam explosion) and compared with respect to how these pre-treatments affect their enzymatic saccharification. Hardwoods were selected for this study, because hardwoods are easier to delignify when compared to softwoods, and therefore their polysaccharides are more easily accessible by enzymes for the purpose of producing fermentable sugars. Currently available commercial enzyme mixtures have been developed for optimal hydrolysis of acid-pre-treated corn stover and are therefore not optimal for saccharification of pre-treated hardwoods. In this work, we attempted the empirical design of a hardwood specific enzyme cocktail, HoloMix. Firstly, a cellulolytic core-set, CelMix (in a ratio of Egl 68%: Cel7A 17%: Cel6A 6%: Bgl1 9%), for the optimal release of glucose, and a xylanolytic core-set, XynMix (in a ratio of Xyn2A 60%: XT6 20%: AguA 11%: SXA 9%), for the optimal release of xylose, were formulated using an empirical enzyme ratio approach after biochemically characterising these enzymes. As it is well ̶ known that biomass pre-treatment may result in the generation of compounds that hamper enzymatic hydrolysis and microbial fermentation, the effects of these compounds on CelMix and XynMix were evaluated. Using the optimised CelMix and XynMix cocktails, a HoloMix cocktail was established for optimal reducing sugar, glucose and xylose release from the various pre-treated hardwoods. For delignified biomass, the optimized HoloMix consisted of CelMix to XynMix at 75% to 25% protein loading, while for the untreated and steam exploded biomass the HoloMix consisted of CelMix to XynMix at 93.75% to 6.25% protein loading. Sugar release by the HoloMix at a loading of 27.5 mg protein/g of biomass (or 55 mg protein/g of glucan) after 24 h gave 70-100% sugar yield. Treatment of the hardwoods with a laccase from Agaricus bisporus, especially wood biomass with a higher proportion of lignin, significantly improved saccharification by the formulated HoloMix enzyme cocktails. This study provided insights into the enzymatic hydrolysis of various pre-treated hardwood substrates and assessed whether the same lignocellulolytic cocktail can be used to efficiently hydrolyse different hardwood species. The present study also demonstrated that the hydrolysis efficiency of the optimised HoloMix was comparable to (if not better) than commercial enzyme preparations during hardwood biomass saccharification. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Date Issued: 2018
The impacts of anthropogenic fires in West African savanna woodlands and parklands: the case of the Guinea savanna, Ghana
- Authors: Amoako, Esther Ekua Amfoa
- Date: 2022-10-14
- Subjects: Firemaking Ghana , Agroforestry Ghana , Parks Fire management Ghana , Nature Effect of human beings on Ghana , Land use Ghana , Savanna ecology Ghana , Traditional ecological knowledge Ghana
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365610 , vital:65764 , DOI https://doi.org/10.21504/10962/365610
- Description: Fire is recognised as an important factor influencing the structure and function of tropical savannas. Despite the extensive studies conducted on the effects of fire on global savannas, there are relatively few studies focusing on fire-assisted land use practices in the agroforestry parkland of the Sudano-Guinean savannas of West Africa. The region experiences recurrent fires in the dry season which begins from November to April. The fires are anthropogenic and are mainly caused through rural livelihoods and cultural practices such as farming - to remove debris from crop fields and to improve soil fertility and hunting to flush out animals, among other reasons. This study therefore sought to: 1. contribute to the understanding of fire-assisted traditional land use practices, people’s knowledge and perceptions of fire use and fire regime: 2. analyse the effects of fire on vegetation, and 3. determine the effects of fire on soils in the Guinea savanna woodlands and parklands of Ghana. Study sites (burnt and unburnt land use types) were selected based on five-year daily fire counts (2013-2017) data, obtained from the Earth Observation Research and Innovation Centre (EORIC), Ghana in collaboration with the Council for Scientific and Industrial Research (CSIR) Meraka Institute, South Africa. Fire densities were calculated for the 18 districts in the Guinea savanna (Northern Region of Ghana). The districts were stratified into low, medium and high fire frequency areas. The East Gonja district recorded the highest fire density (1.0 fires km-2) while Tamale recorded the lowest fire density (0.3 fires km-2). Of the eighteen districts, six districts were purposively selected and ten communities sampled. Firstly, I investigated the frequency of fire use and control, perceptions of fire regime for selected livelihood and socio-cultural activities in the six districts. The majority of respondents (83%) across the study districts indicated that they used fire once a year for at least one of the following activities: land preparation, weed/grass/pest control, burning stubble after harvest, bush clearing around homesteads, firebreaks, charcoal burning and hunting. The study showed the highest frequency of fire use in the dry season was for land preparation for cropping. However, less than a fifth of the respondents (17%) indicated that they did not use fire for any of the above activities. The results of a multiple regression predicted fire activities in the dry season from gender, age, level of education, occupation and household size. Secondly, the study examined how fire influenced the population structure and abundance of two economically important woody species Vitellaria paradoxa C. F. Gaertn. (Shea tree) and Anogeissus leiocarpa (DC.) Guill. & Perr. (African Birch) in burnt and unburnt land-use types. Stand basal area, mean densities of juveniles and adult trees and Simpson’s index of dominance were determined. Eight diameter size classes of each species were analysed by comparing their observed distributions to a three-parameter Weibull distribution across the land use types. A total of 3,366 individuals of A. leiocarpa (n = 1,846) and V. paradoxa (n = 1,520) were enumerated. The highest total basal area of Anogeissus leiocarpa (16.9 m2/ha) was estimated in sacred groves whereas Vitellaria. paradoxa (20.6 m2 /ha) was found in unburnt woodland. The highest mean densities of A. leiocarpa (22.7±29.7 stems/ha) and V. paradoxa (15.3±2.2 stems/ha) were found in sacred in groves. Anogeissus leiocarpa was, however, absent in fallows and burnt crop fields. A somewhat inverse J-shaped distribution was found in sacred groves for both species. Thirdly, the study compared species composition in early burnt, late burnt and unburnt plots in a protected area where fire was regulated. Vitellaria paradoxa C. F. Gaertn., Terminalia avicennioides Guill. & Perr., Combretum adenogonium Steud. ex A. Rich. and Combretum molle R. Br. Ex. G. Don. were the most common and abundant in all treatments. Late burnt and unburnt plots recorded the lowest diversity amongst the three treatments. Unburnt plots had higher tree density than burnt plots. A Detrended Canonical Analysis showed a changing trend, indicating a moderately strong positive association between burning time and species composition. The first and second axes contributed 53% and 12% variation, respectively. Most of the species found in axis one had fairly strong positive association to early and late burnt treatment than unburnt treatments. Finally, the effects of fire on soil properties in burnt and unburnt crop fields and woodland in the ten communities were also investigated. A total of 151 composite samples in selected burnt and unburnt land use types (burnt crop field n=20; unburnt crop field n=27; burnt woodland n=53, unburnt woodland n=51) were analysed. The variables analysed were pH, soil organic carbon (SOC), total nitrogen (TN), available phosphorous (P), Exchangeable bases - potassium (K), magnesium (Mg), calcium (Ca), cation exchange and soil texture. Total N, SOC, pH and Ca differed significantly across the burnt and unburnt land-use types. A principal component analysis showed a stronger association and more positive gradient in woodlands than in crop fields. Total N showed a positive association with SOC, whereas silt showed a negative association to sand and clay. Traditional knowledge and perceptions of users of savanna agroforestry parklands can inform the formulation of local by-laws for community fire management as well as national policy regulation on fire use in the savanna through the interlinked analysis of social and ecological systems as have been elucidated in this study. The results on vegetation assessment revealed that fire practices and land uses influenced size class distribution of the two study species as well as the densities of woody species in traditional crop fields and the National Park. The unstable populations observed in most land uses and the absence of A. leiocarpa in crop fields and fallows call for education and policy actions on the use of fire in parklands of West Africa. Furthermore, fires positively influenced some soil properties in both woodlands and crop fields confirming one of the emphasised reasons why rural subsistence farmers use fire. As an environmental management decision and land use policy intervention, early dry season burning could be an option to curbing the indiscriminate and unplanned fire use. Also, the protection of trees on farm lands could check the unstable population structure of economically important woody species leading to the different structures that deviated from the recommended reverse J-shaped distribution curve observed in these agroforestry parklands. The management of socio-ecological systems such as the agroforestry parklands of West Africa require a holistic understanding of the complexity of the different resource systems, units and actors involved for sustainable management of these natural resources. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Date Issued: 2022-10-14
Development of biosensor systems for the detection of anti-cancer drugs and prostate cancer
- Authors: Mwanza, Daniel
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365929 , vital:65803
- Description: Thesis embargoed. Expected release date early 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Date Issued: 2022-10-14
Towards the Common Good: An expansive post-abyssal (Re)stor(y)ing of the epistemic cultures of the citizen sciences
- Authors: Vallabh, Priya
- Date: 2022-04-08
- Subjects: Science Citizen participation , Decolonization , Social epistemology , Hegemony , Common good , Traditional ecological knowledge , Ethnoscience
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/290671 , vital:56773 , DOI 10.21504/10962/290671
- Description: In this study I explore and explain transformatiThe citizen sciences convene complex and reflexive ecologies of knowledges in response to a range of social-ecological risks. Their epistemic cultures seem to be assembled in ways which increase potential mobilisation of the common knowledges being produced, thereby producing knowledges in forms that are more strongly aligned with a range of implementation strategies. However, much of such processes of knowledge production have been ‘cleaned out’ of official accounts through scientifically hegemonic systems of legitimation, deepening hegemonically-entrenched systems of epistemic, contributory and distributive injustices, and undermining the potential for stronger enactments of participatory and radical democracies. The engagement of sociologies of absences and emergences in this study evidence these epistemic insights, thereby evidencing an expansive post-abyssal (re)stor(y)ing of the citizen sciences. Through this research, I consider knowledge production as ‘commoning', towards the constitution of the common good. To date, most accounts of knowledge production within citizen science projects primarily focus on scientific processes of knowledge production and legitimation. Such accounts neglect the ecologies of diverse knowledges through which knowledge is being collaboratively produced, the forms of learning that occur, or the ways in which such ecologies are mobilised in response to specific socialecological risks. To better understand the ways in which citizen science projects build risk-responsive common knowledge, I bring a focus to the diversity of epistemic cultures convened, speaking to this gap. My primary research question is: How do the epistemic cultures within citizen science projects enable commoning in response to social-ecological risk? To begin, I establish a particular vantage point from which the remainder of the thesis is launched, one which centres as the primary interest of knowledge production, an interest in social-ecological justice and the constitution of the common good. From this vantage point, knowledge co-production and learning can be viewed as acts of commoning, which themselves constitute common goods. I draw on the work of Karin Knorr Cetina to conceptualise and frame notions of epistemic cultures and their epistemic features. Expanding notions of epistemic cultures from a post-abyssal perspective, I draw on the work of Bruno Latour and Boaventura de Sousa Santos. Latour’s distinctions between the production of ‘matters of fact’ and ‘matters of concern’ provide a way to challenge hegemonic systems of scientific knowledge production, while preserving the potential emergence of multiplicity in the context of evolving risk, thereby enabling a greater degree of situated reflexivity. Santos argues for the reclamation of all ways of knowing, including but not limited to scientific ways of knowing the world. He argues that other forms of knowledge are produced as nonexistent, and that they might be reclaimed through engaging sociologies of absences and emergences. Both authors enable a stronger analysis of knowledge production in terms of its ability to intervene into context in response to manifest risks. These three theoretical approaches are convened into an analytical framework for the study. To enact sociologies of absences and emergences, I engage two forms of immanent critique, complemented by an epistemic mapping of 50 South African citizen science projects, and an analysis of three illustrative case studies. The first critique is one of produced nonexistence, through which I consider three aspects of the general knowledge cultures within which the epistemic cultures of citizen science projects are situated. This critique makes evident the ways in which the ontological and related conceptual structures of hegemonic scientific knowledge production actively produce as nonexistent, other onto-epistemic contributions to knowledge production in response to social-ecological risks. The second critique reviews the field of peer-reviewed literature through a reading of presence and absence, with a focus on the articulation of epistemic cultures. Predictably, a key finding is that this form of scientific reporting primarily foregrounds legitimated scientifically processed knowledge, while once again producing as nonexistent, other forms of knowledges. However, there is evidence of increasing accounts of citizen science which recognise both a diversity of knowledge contributions, and epistemic, contributory and distributive justice issues as regards hegemonic forms of reporting. The epistemic mapping evidences a highly diversified field of citizen sciences, whose epistemic cultures are convened to produce distinct forms of scientifically-informed knowledges in response to diverse contexts, scales and notions of risk. The three illustrative case studies engage sociologies of absences and emergences, with particular focus on articulating the ecologies of knowledges evidenced in project documentation, including both official and unofficial accounts of epistemic activity. This analysis highlights the significant contributions of diverse forms of knowledges, including scientific, situated, embodied, governance, indigenous, spiritual and relational knowledges, and the ways in which these knowledge are convened to respond to specific configurations of risk. It once again highlights issues of epistemic, contributory and distributive justice, and makes evident the need for stronger integrity in processes of producing and reporting common knowledges. The case studies also illustrate the increased effectiveness of leveraging an ecology of knowledges (in contrast to a monoculture of scientific knowledge) in response to situated risks, including how such ecologies have a tendency to be generative and enable multiple forms of intervention into structures and applied contexts of intervention. In response to the collective research findings, a think-piece on rigour-as-integrity is offered as a contribution to commoning, in response to social-ecological risk. The piece draws together a postabyssal system of rigour intended to strengthen knowledge production in ways which actively centre forms of justice and commoning. ve potential in arts-based environmental learning with a focus on water pedagogy. The study took place over a period of four years, where approximately 40 school pupils between the ages of 10 and 17 years-old were engaged in participatory arts-based inquiries into water located across unequal neighbourhoods in Cape Town, South Africa. Educators, school learners, citizens and decision-makers hold different historical, cultural, political and spiritual perspectives on water. These play a role in shaping what is termed in this research the ‘hydro-social cycle’. Yet, due to dominant ideas of what counts as knowing and truth, educators in educational settings struggle to account for the complexity of water, limiting educational encounters to a partial knowing leading mostly to limited unimaginative framings of problems and solutions. My focus on transformative potential in learning is derived from a concern for how environmental education encounters and the sense-making they enable, are infused by socio-economic, political, and historical elements, specifically colonialism, capitalism, and white supremacist racism. The connections between the multiple layers of capitalist crisis and the ever-urgent environmental crisis are not adequately made in mainstream forms of water education. The research explores how arts-based pedagogy could enable a productive meeting of critical environmental education with ecological literacies. Within this positioning, transformative potential considers how educational engagements position questions about water within the social life of participants/learners and inform learning that leads to fuller and more nuanced greater knowledge. Theoretically, I work with an interrogation of critical education theory, underlaboured by critical realism which enabled me to rigorously consider how claims to knowing are shaped by their accompanying assumptions of what is real. Drawing on recent debates in critical education theory, I resist the notion of critique as ideology and engage instead in the craftsmanship of contextual and responsive inquiry practice. This has enabled me to articulate processes and relationships in water education encounters with meaningful understandings of the effects of simultaneous crises rooted in racial capitalism and environmental crisis. My methodological approach is arts-based educational research with a directive to reflect upon educational encounters in an integrated way. It includes two parts informing the facilitation and analysis of open-ended learning processes. One component was arts-based inquiry practice developed for exploring complexity, drawing on the thinking of Norris (2009, 2011) and Finley (2016, 2017). The second part holds reflective space for these encounters guided by the practice of pedagogical narration inspired by the Reggio Amelia approach, demonstrated by Pacini-Ketchabaw, Nxumalo, Kocher, Elliot and Sanchez (2014). Clarifying the intellectual work of a responsive educator-researcher, pedagogical narration brings multiple theoretical lenses into conversation with emergent dimensions of educational process. In practice, in order to transgress the dominance of colonial white supremacist knowledge frames of water, I needed to be curious, to be confounded, to expect the unexpected in the educational encounters with participants and this mirroring of practice was emulated by the participants as they followed their own questions about water in Mzansi (South Africa). In our work together we came up against assumptions we had previously not questioned as individuals. Together we explored the implications of this by, for example, questioning who is responsible for saving water. These explorations required bringing together science knowledge and everyday knowledge at multiple scales: the household, catchment, government and global. It required us to be critical of how language and images are mobilized in public communication and school curriculums; for example, representations of water are infused with history and power in a way that impacts how we know and teach about water. The transformative potential of this pedagogical space is generated through acts of creative expression which are seen as acts of absenting absence, for example exhibiting through play how water use in the household interconnects with gender and age relationships. As such, creative expression through multiple mediums or more-than-text enables a deeper understanding of water as well as openings for interdisciplinary engagement with learning about water. My research found that in bringing together the contributions of critical education and environmental education in practice, two shifts are needed: environmental educators need to view ecological literacy as inseparable from the social and political. The knowledge that is shared about water in the classroom has social and political implications. On the other hand, critical educators need to better locate justice concerns in the material and ecological world at scale. Arts-based inquiry, as a kind of scaffolding for pedagogical process, has the potential to enable these shifts by opening up fixed analytical frames. Making these shifts requires a reflective practice on the part of the educator to navigate the inherited blind spots in environmental learning and critical education, such as dualities. One way to do this is for the educator to identify absences, as articulated in the Critical Realist tradition, and consider how these absences might be absented. This differs from a simplistic process of critique in the possibilities it opens up for collaboration between different schools of thought rather than further polarisation and alienation between educators and knowledge keepers on social ecologies. These insights have relevance for many sites of environmental education practice, such as natural science lecturers, school teachers or community activists. It is knowledge-learning work emergent from and responsive to complex ecological crisis, which requires everyone to rethink and open up to new ways of being, seeing and doing around these issues. The transformative potential of this work is that the thinking and transforming at all scales can be catalysed and grounded through the arts based educational encounters with the participants. , Thesis (PhD) -- Faculty of Education, Education, 2022
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- Date Issued: 2022-04-08
Saul Msane: friend or foe of the people? The life of the late nineteenth to early twentieth centuries South African politician and journalist
- Authors: Mokoatsi, Thapelo
- Date: 2023-03-30
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/409799 , vital:70631 , DOI 10.21504/10962/409802
- Description: Saul Msane was a prominent founding member of the ANC and an active journalist and editor of the ANC newspaper Abantu-Batho. His career generated controversy. Towards the end of his life, he had a feud with his colleagues in the African National Congress (henceforth Congress) that led to him being labelled isitha sabantu, “the enemy of the people” for his refusal to support the Shilling strike of 1918, an accusation which was retracted a year after his death in 1919. The label of isitha sabantu levelled against Msane, had the effect of ending his political prominence in the Transvaal, forcing him to relocate to kwaNongoma where he died shortly thereafter. Msane’s years in the Congress amounted to about seven years, between 1912, the founding of the Congress, and the demise of his career in 1919. Msane’s seven years in Congress were characterised by controversies, clashes, and conflicts owing to his perceived elitism. In Congress historiography Msane is an obscure and elusive figure, he lives here and there in a footnote, as a supporting statement or a mentioned in mere passing. His marginalisation reveals some of the gaps within the history of Congress and invites us to write about those who did not emerge from the history of Congress necessarily as heroes. This thesis sets out to write a biography of Msane and document his political career beyond that one moment in which he came to be “isitha sabantu”. While Msane’s Congress career was comparably short and filled with tensions, an archive of his life exists. This study is an exploration of that archive to reconstruct the biography of a once prominent leader who dies in political exile from the Congress movement. This thesis sets out to do two key things in relation to reconstructing Msane’s life: Firstly, it reconstructs the longer biography of Msane’s political life by drawing on the existing archives, and thus filling in the South African historical record in that regard. Secondly, at the broader conceptual and historiographical level, it argues that the controversies surrounding Msane’s persona and character illustrate that conceptions of elitism and the nature of being ‘elite’ were key to the politics of Congress at the time. , U-Saul Msane wayengomunye wabasunguli beqembu lika-African National Congress (uKhongolose) futhi eyIntatheli nomhleli wephephandaba i-Abantu-Batho. Umsebenzi ayewenza waba nezingqinamba eziningi ngokwezepolitiki. Ngasekugcineni kwempilo yakhe waba nokungazwani nabaholi ayesebenza nabo kuKhongolose okwadala ukuba abizwe ngesitha sabantu ngenxa yokuba engavumelananga nesiteleka sango-1918 lapho abasebenzi babelwela ukukhushulelwa amaholo. Leligama lokubizwa ngesitha sabantu lahoxiswa ngo 1919 sekudlule unyaka engasekho emhlabeni. Lokubizwa ngesitha sabantu kwalilimaza igama lakhe kwezepolitiki e-Transvaal waze wathutha wayohlala kwaNongoma nokuyilapho ashonela khona. Iminyaka uMsane ayisebenzele uKhongolose yaba isikhombisa, kusukela ekusungulweni kwayo ngo 1912 kuze kufike ekulimaleni komsebenzi wakhe wezepolitiki ngo 1919. Kuleminyaka eyisikhombisa umsebenzi wakhe kuKhongolose wawubhekene nokugxekwa okukhulu nokubukeka njengomuntu onokuzenza ngcono kunabanye abantu. Emlandweni kaKhongolose uMsane akavezwa ngendlela emfanele, kukhulunywa ngaye kudlulwa nje. Lokunganakwa kukaMsane emlandweni kaKhongolose kusiphoqa ukuba sibhale ngabaholi abangaqakanjiswa. Lolucwaningo luveza umlando kaMsane ngokujulile ngaphezu kwangalesikhathi abizwa khona ngesitha sabantu. Noma umsebenzi kaMsane kuKhongolose wabamfushane kunabanye futhi ugcwele izinto kodwa noko ingobo yawo ikhona. Lolucwaningo lucubungula lengobo ukuhlaziya nokubhala kabusha umlando wengqalabutho eyagcina ishonela ngaphandle kombutho kaKhongolose. Loluphando lifisa ukwenza izinto ezimbili: Okokuqala, ibhala kabusha umlando omude wezepolitiki kaMsane kusetshenziswa ulwazi olukhona. Loku kuzosiza ukunothisa umlando wezepolitiki wezwe laseNingizimu Afrika. Okwesibili, ezingeni lobunzululwazi, lolucwaningo luveza ukuthi izinkinga uMsane ahlangabezana nazo zazisukele endleleni okwakubukwa ngayo indaba yokucwasana ngazinga empilo abantu, kwakuyinto ejulile kuKhongolose ukubukeka kwabanye sengathi bazenza ngcono. , Thesis (PhD) -- Faculty of Humanities, History, 2023
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- Date Issued: 2023-03-30
The nexus between territorial border controls, informal cross border trading and economic security in Zimbabwe: the case of Beitbridge Border Post
- Authors: Nare, Hilary
- Date: 2022-10-14
- Subjects: Informal sector (Economics) Zimbabwe , South Africa Commerce Zimbabwe , Border security Zimbabwe , Economic security Zimbabwe , Beitbridge (Zimbabwe) , Zimbabwe Politics and government , Zimbabwe Economic conditions
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365977 , vital:65807 , DOI https://doi.org/10.21504/10962/365977
- Description: Informal cross border trade is central to the lives of many Zimbabweans, with informal trade across the Zimbabwean-South African border being of particular importance. This entails travelling through the Beitbridge border post on the Zimbabwean side, with Zimbabwean informal traders purchasing items in South Africa for resale in Zimbabwe. In doing so, they contribute not only to their own economic security but likely to the economic security of other Zimbabweans deeply affected by the ongoing crisis in the country. Often times, when examining the lives of Zimbabwe’s informal traders, the border post is not subjected to sustained focus and analysis. Yet, border posts (like the Beitbridge border post) are complex social institutions which configure the lives and livelihoods of cross border traders in multiple ways, and which informal traders often have to negotiate their way through. In this context, this thesis provides a critical analysis of border control management at the Beitbridge border post with particular reference to the activities of Zimbabwean informal cross border traders. The Beitbridge border post, like all border posts, has multiple functions. As a territorial border post, it seeks to maintain the national sovereignty of the Zimbabwean nation- state, and it monitors and controls the movement of people and goods in both directions. Currently, it is doing so at a time when the vast majority of Zimbabweans are suffering from varying levels of economic insecurity. The extent to which these functions are performed, and the manner in which they are performed, depends fundamentally on what takes place at the Beitbridge border post. This refers to the performance of both human subjects (border control officers of various kinds) and inanimate objects (such as scanners and cameras), both of which enact agency. Combined with these is the agency of cross border traders, who are compelled to navigate their way in and through these dimensions of the border control system. The thesis examines this by drawing heavily upon Actor-Network Theory. It is based on research undertaken at Beitbridge border post, involving 50 interviews with primarily current and former border control officers as well as informal cross border traders. Findings of this study show that deficiencies in border control management and border porosity at Beitbridge have led to a flourishing of informal cross border trade and, in turn, contributed to economic security in Zimbabwe, including during the time of Covid-19. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2022
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- Date Issued: 2022-10-14
Uncoupling the exploitation and climate change effects on the biology of Cape monkfish, Lophius vomerinus Valenciennes 1837 in Namibia
- Authors: Erasmus, Victoria Ndinelago
- Date: 2021-10-29
- Subjects: Lophius Namibia , Lophius Climatic factors Namibia , Lophius Effect of human beings on Namibia , Lophius Food Namibia , Lophius Reproduction Namibia , Lophius Age Namibia , Lophius Growth Namibia , Lophius Habitat Namibia , Lophius Conservation Namibia , Fisheries Namibia , Overfishing Namibia , Fishery management Namibia , Lophius vomerinus (Valenciennes, 1837) , Cape monkfish
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/188329 , vital:44744 , 10.21504/10962/188329
- Description: Cape monkfish, Lophius vomerinus Valenciennes 1837, has supported the Namibian fishing industry for decades, historically as by-catch and recently as a target species. This species is also an important predator in this region. With increasing levels of exploitation and unprecedented climate change, an understanding of the changes in the long-term biological parameters of this species is critical. To date, there has been a scarcity of spatio-temporal studies that have examined and compared the biological aspects of Cape monkfish in relation to climate change and exploitation pressure. Investigations into changes in feeding habits, reproduction strategy, age and growth can provide valuable information for the sustainable management and conservation of this species. This thesis aimed to improve our understanding of the impacts of exploitation and climate variability on the biological parameters of Cape monkfish in the Namibian marine waters, thereby contributing to efforts directed at sustainable harvest and management of this resource. This was achieved through temporal and spatial comparisons of feeding, reproductive scope, age and growth, and catch statistics. The study used data collected during the monkfish swept-area biomass surveys of 2001–2005 and for 2007–2018, hake (deep-water hake Merluccius paradoxus Franca 1960 and shallow-water hake M. capensis Castelnau 1861) swept-area biomass surveys of 2017 and 2019, port sampling programme data collected from April 2014 to December 2019, and monkfish commercial fishing activities collected between April 2001 and December 2019. Based on historical feeding data (1986 – 1987) and contemporary feeding data (2015-2018), Cape monkfish feeds on a variety of prey species from seven groups: Teleost, Cephalopoda, Crustacea, Echinoidea, Elasmobranchii, Gastropod and Porifera. The diet was characterised by a high prevalence of empty stomachs (43.9%), showing low feeding intensity, but most prevalent in juveniles (52.9%). Although the diet composition varied at different life stages, Teleosts (especially deep-water hake Merluccius paradoxus Franca 1960) were the main constituents of the diet for all size classes as per the Index of Relative Importance (%IRI). The results highlight the particular importance of the deep-water hake M. paradoxus (by %IRI) in the diet of Cape monkfish across all size classes. There is a clear dominance of hake in both studies, which means that any overexploitation or climate-driven population decline in hake will most likely have an impact on Cape monkfish. Feeding composition was dependent on the season (p < 0.05), with the type and quantity of prey ingested changing seasonally, showing the ability of Cape monkfish to adjust its diet, depending on possible environmental parameters which consequently influence prey availability. In general, the spatial and temporal variability of the main prey items suggests that the species is highly opportunistic with a broad trophic adaptability. Comparison of historical and contemporary stomach content data indicates that Cape monkfish appear to have changed their diet, probably reflecting the availability of forage species over time and space, possibly due to climate change, fishing pressure, or both. The broad trophic adaptability for Cape monkfish highlights their adaptive potential to increasing anthropogenic stressors such as climate change. However, the dominance of the commercially important deep-water hake, M. paradoxus, in the diet during contemporary times highlights that complex trophic interactions may play a role in altering the northern Benguela fisheries. The general male to female sex ratio was measured at 1:1.67, with significant variation across depth, size class, and year (p < 0.05). Comparison of length at 50% maturity (L50) for Cape monkfish between historical (2004–2006) and contemporary time (2015–2019) showed no significant differences in both sexes, with no significant changes in the L50 for females (χ2 = 1.53, df = 1, p = 0.2154), and males (χ2 = 0.41, df = 1, p = 0.5204) between the two periods. The monthly gonadosomatic index (GSI) showed that Cape monkfish spawn throughout the year with peaks between July and September for females and August for males, similar to those observed 20 years ago. Spawning hotspot areas were identified and were consistently located between 22⁰ and 25⁰S in deeper water (> 250 m) for the 2001–2018 time series. Comparison of the contemporary (2015–2019) proportions of developing, ripe and spent gonads to the historical study data (1996 – 2000) show minimal differences. Ripe ovaries capable of spawning (Stage IV) were dominant in July (23.8%) and August (26.2%), while ripe testes were prevalent in April (52.5%) and November (28.5%). The discovery of the veil (a gelatinous, flat ribbon structure containing individual eggs) off Namibia for the first time (during this study) is a significant because this result provides important reproduction activities information of this species, which were never recorded off Namibia. The location where the veil was discovered, off Swakopmund (22⁰30'S, 13⁰25'E), provides further evidence of the identified spawning hotspot areas, this location is also identified as a monkfish consecutive hotspot fishing area. The ages, growth rates, and length-weight relationships were compared between fish collected during monkfish commercial fishing activities between 1996 and 1998 (Period 1) and during monkfish routine monitoring surveys from 2014 to 2016 (Period 2). A total of 607 (size range: 9–96 cm total length (TL)) and 852 (size range: 9–96 cm TL) Cape monkfish were aged by reading sectioned illicia, during Periods 1 and 2, respectively. The length-weight relationships were W = 0.012L3.035 (r2 = 0.98) and W = 0.014L 2.989 (r2 = 0.98) for females and males, respectively, during Period 1, and W = 0.01L2.97 (r2 = 0.98) and W = 0.01L 3.03 (r2 = 0.98) for females and males, respectively, in Period 2. The growth of Cape monkfish (in cm) for combined sexes was described by Lt = 94(1 − e(−0.10(t−(-0.31))) in Period 1 and Lt = 98(1 − e(−0.10(t−(-0.33))) in Period 2. Females grew significantly faster during Period 1 (LRT results from Maartens et al., 1999), while male and female growth was not significantly different during Period 2 (F = 0.65, p = 0.58). There were no significant differences between the male and female growth curve in Period 2 (F = 0.65, p = 0.58). Although the growth curves are similar between Period 1 and Period 2, the larger fish are in Period 2 are lighter than those in Period 1. This finding is important to the monkfish fishing industry because fish is sold by weight. This finding may suggest that although the fish grow similarly by length, changes in the environmental conditions may have resulted in a reduced condition of the fish. In terms of mean age, the historical Period 1 had a slightly lower mean age of 4.40 compared with a mean age of 5.49 during Period 2. Slight differences were also observed in the age structure between the two periods, with 2-year-olds (20.3%) the most abundant age class in the historical period while 5-year-old fish (18.3%) were most abundant in Period 2. Although the spatial distribution of the catch was not available for Period 1, 0-year-old fish were distributed from 22⁰ to 24⁰S, and 25⁰ to 26⁰S in shallower waters of 166–290 m during Period 2. Only fish between 5 and 16 years old were found off the documented historical nursery area off 28º S. The similar growth curves and spatial overlap of nursery habitats between Period 1 and Period 2 suggest that Cape monkfish may be fairly resilient to the rapid environmental change reported in this region and to the extensive levels of exploitation for the species. However, the recent spatial shifts in the nursery areas are sensitive to disturbance and may indicate that these changes could be having an impact on the early life stages of the species. Continued monitoring may be necessary to understand the consequences of these spatial shifts for the age and growth and resilience of the species. Analysis of the overall spatial and temporal catches of monkfish (both Cape monkfish and shortspine African monkfish) off Namibia between 1998 and 2018 identified noticeable spatio-temporal trends. The pattern of fishing activities for Cape monkfish is heterogeneous, with identified ‘hotspots’ in specific areas. Of particular importance is the consecutive hotspot, between 1998 to 2018 for monkfish fishing activities between 25⁰ and 26⁰ S. The kernel density analysis indicated that the area around 24⁰S, and between 26º and 27 ⁰S, between Walvis Bay and Lüderitz, had the highest total catch densities (~300 kg/km2), suggesting that this is the core of the stock abundance. Annual monkfish catches have fluctuated since the inception of the fishery in 1994, with a drastic decline in the catch recorded after 2003 through to 2018. Generally, there has been an underutilisation of the total allowable catch (TAC) for most of the years. The decrease in catches and the underutilisation of the TAC might be indicative of the reduction in the stock abundance. However, external factors such as lack of capacity of the fishing industry and the administration can contribute to underutilisation of TAC. Basic regression analysis between total monthly catches and monthly sea surface temperature (SST) yielded low r-squared values indicate that in all three grids, only ~ 1% of the variation is explained between SST and total monkfish catches in these areas. The most prominent points to consider from this study are the results of the comparative feeding study (Chapter 3), reproductive indicators (Chapter 4) and age and growth (Chapter 5). Certainly, there have been changes in feeding, demography, and distribution of the species in the last two decades – climate-driven changes were recorded in the feeding habits of Cape monkfish, spatially and temporally – but despite the changes in prey species composition, distribution and abundance in various habits and periods, Cape monkfish was able to switch prey species, reflecting wide trophic adaptability. The dominance of M. paradoxus at all size classes in all analysed habitats is a significant result because. The peak spawning period has remained the same between July and September, as previously reported in Period 1. The consecutive spawning hotspots were identified in the areas between 22º and 25ºS. From a fisheries management perspective, the spawning ground and spawning season should be protected (by means of closure). The evidence of changes in length at 50% maturity presented in this study hints at both climate change and extensive exploitation pressure. The discovery of the veil for the first time in this study is very important; however, it might be sampling related and not driven by climate or exploitation pressure. Finally, the change in the Cape monkfish distribution discussed in Chapter 6 may be attributed to a shift in the distribution or fishing effort as a consequence of shallow water depletion. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
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- Date Issued: 2021-10-29