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Technology in conservation: towards a system for in-field drone detection of invasive vegetation

  • Authors: James, Katherine Margaret Frances
  • Date: 2020
  • Subjects: Drone aircraft in remote sensing , Neural networks (Computer science) , Drone aircraft in remote sensing -- Case studies , Machine learning , Computer vision , Environmental monitoring -- Remote sensing , Invasive plants -- Monitoring
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/143408 , vital:38244
  • Description: Remote sensing can assist in monitoring the spread of invasive vegetation. The adoption of camera-carrying unmanned aerial vehicles, commonly referred to as drones, as remote sensing tools has yielded images of higher spatial resolution than traditional techniques. Drones also have the potential to interact with the environment through the delivery of bio-control or herbicide, as seen with their adoption in precision agriculture. Unlike in agricultural applications, however, invasive plants do not have a predictable position relative to each other within the environment. To facilitate the adoption of drones as an environmental monitoring and management tool, drones need to be able to intelligently distinguish between invasive and non-invasive vegetation on the fly. In this thesis, we present the augmentation of a commercially available drone with a deep machine learning model to investigate the viability of differentiating between an invasive shrub and other vegetation. As a case study, this was applied to the shrub genus Hakea, originating in Australia and invasive in several countries including South Africa. However, for this research, the methodology is important, rather than the chosen target plant. A dataset was collected using the available drone and manually annotated to facilitate the supervised training of the model. Two approaches were explored, namely, classification and semantic segmentation. For each of these, several models were trained and evaluated to find the optimal one. The chosen model was then interfaced with the drone via an Android application on a mobile device and its performance was preliminarily evaluated in the field. Based on these findings, refinements were made and thereafter a thorough field evaluation was performed to determine the best conditions for model operation. Results from the classification task show that deep learning models are capable of distinguishing between target and other shrubs in ideal candidate windows. However, classification in this manner is restricted by the proposal of such candidate windows. End-to-end image segmentation using deep learning overcomes this problem, classifying the image in a pixel-wise manner. Furthermore, the use of appropriate loss functions was found to improve model performance. Field tests show that illumination and shadow pose challenges to the model, but that good recall can be achieved when the conditions are ideal. False positive detection remains an issue that could be improved. This approach shows the potential for drones as an environmental monitoring and management tool when coupled with deep machine learning techniques and outlines potential problems that may be encountered.
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  • Date Issued: 2020

The application value and most appropriate mapping scales for site classification and evaluation in the South African forest industry

  • Authors: Sibhakabhaka, Thembisa
  • Date: 2020
  • Subjects: Forests and forestry -- South Africa , Forest products industry -- South Africa Geographic information systems
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/49281 , vital:41617
  • Description: The South African forest industry is challenged with aspects related to socio-political developments, conflicts with biodiversity values, uncertainties related to climate change, several biotic and abiotic risks, and a limited potential for expansion. For this reason, efficient and optimal land-use is essential, which requires sustainable forest management practices and accurate information and decision support systems. Tree growth patterns, productivity and risks vary according to changes in geology, topography, climate and soil conditions. It is therefore required that forest managers, planners and researchers have a conceptual understanding of the concept of forest site classification and evaluation. This is essential not only for improved levels resilience, but also to maintain a competitive industry in terms of socio-economic and environmental performance. The first chapter of the study aimed to investigate the perceptions and interpretations of a range of representative stakeholders from the forestry industry regarding the value, shortcomings, requirements and design of forest site classification and evaluation systems in use in the local industry. A questionnaire with 16 questions was used for this purpose, and data was analysed using quantitative and qualitative techniques. Results indicated variable levels of understanding amongst respondents of terminology and the nature of systems used in industry. Trends in responses were influenced by the background of stakeholders, the role of individuals in the value chain of forestry as well as past experiences. The perceived importance and value of potential site evaluation applications varied substantially amongst different stakeholders. Results point towards a narrow-focus application for site classification and evaluation systems for site-specific forestry, with a lesser regard with aspects of risk management and environmental performance. Several technical aspects related to site variables, data resolution and scale of presentation were also questioned by participants. Listed priorities for research and development include the integration of site classification and evaluation systems into corporate information systems, modernizing technology, more appropriate site evaluation models, advanced climatic modelling and the development of indices of water and nutrient availability related to forest productivity. There is general agreement for the development of a national forest site classification system. The value of this part of the study lies in the contribution it makes towards our knowledge of stakeholder perceptions regarding site classification and evaluation, as well as the valuable comments made by participants for the refinement of such systems that can serve as indicators for entities involved in education, governance and strategic forest management. The second data chapter of the study involved the development of high-resolution site classification systems in the form of Site Types for two selected study areas in South Africa, one located in Mpumalanga, and the other in the southern Cape. This enabled a comparative analysis with existing low-resolution Land Type classifications that were developed by different authors for the same two study areas, in terms of its reliability, accuracy and general usefulness for applications in the plantation forestry value chain. The comparison of the two types of classification systems revealed that the climate data forming part of the database were of equal accuracy and resolution. However, an obvious difference was detected in the information pertaining to soil in terms of descriptive and spatial data. In the case of both study areas, the Site Type classification systems revealed many soil and geological features that were not indicated by the lower-resolution Land Type systems. Variation in characteristics related to parent material, soil classification, soil depth, intensity of subsoil wetness and soil organic matter were not adequately reflected in these systems. This can potentially have important implications for applications such as species choice, predictions of yield, nutrient optimization, ratings of soil resilience, biodiversity management and evaluations for carbon sequestration potential. The data forming part of this study indicate that although Land Type classification systems can provide valuable support at strategic levels of planning and management, there are several limitations for use at finer scales of resolution. The final chapter of the study includes an investigation and qualitative comparison of the usefulness of Site Type vs. Land Type classification systems, based on existing knowledge in the industry. The two systems are compared in terms of its input towards the following applications: site-species matching, timber yield prediction, site amelioration / site preparation requirements, nutrient management requirements, vegetation management / weed control, management of pests and diseases, determination of risk for soil compaction, soil erosion and nutrient loss, decision making regarding forest engineering operations, prediction of wood / fibre properties, biodiversity management and lastly planning of research activities / priorities. This analysis indicated that applications that require data on only climate and general soil patterns can be supported with equal success by both types of site classification systems. On the other hand, in cases where high-resolution data on site factors are required, Land Type classification systems had numerous shortcomings and received a much lower rating of suitability. The outcome of the study can provide guidance on the development and design of future site classification and evaluation systems for the South African forest industry. High-resolution databases of key site factors should receive priority, together with the development of decision support systems based on causal relationships. This will contribute to the resilience and sustainability of an industry that is increasingly confronted with questions related to the placement, design and management of forest plantations.
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  • Date Issued: 2020

The effect of age and maturation on anthropometric characteristics and physical abilities of youth South African footballers

  • Authors: De Beer, Ashley
  • Date: 2020
  • Subjects: Soccer -- Physiologial aspects , Soccer players -- South Africa -- Makhanda -- Physiology , Soccer players -- South Africa -- Makhanda -- Psychophysiology , Makana Local Football Association (South Africa)
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/141222 , vital:37954
  • Description: Currently there is limited research investigating the football related abilities of youth South African individuals. Populations from North and South America, Europe and Asia have been extensively covered in terms of their anthropometric characteristics, physical abilities, technical competency, tactical understanding as well as various personality traits. In describing these details, and especially how each is affected during the ageing and pubertal process, a more informed understanding of the talent development systems is created. A holistic approach to talent development is required to effectively and efficiently produce elite level footballers. An important consideration is the unique socio-economic environment many youth footballers experience which may impact on the talent development process. The present study therefore sought to quantify the anthropometric characteristics and the physical ability level of youth South African footballers from Local Football Association in Makhanda in the Sarah Baartman Region of the Eastern Cape province. In order to achieve this a two-factorial design was used with age and maturity status as independent variables. Anthropometric characteristics were tested by finding the height, weight, body mass index and total fat percentage of participants. Physical ability was determined by results for aerobic capacity, power, acceleration, speed and agility. All tests were football specific and had been widely used in a variety of footballing studies. Additional demographic and socio-economic information was also recorded. A total of 136 participants were placed in their respective Under 11, 13, 15 or Under 19 age groups, while the maturity status of 96 participants were stratified into five distinct categories. Statistical analyses was conducted using p-value significance, with appropriate Tukey post-hoc tests administered when necessary, while effect sizes were calculated using Cohen’s d. Significant changes and practical effect sizes were present for nearly all dependent variables when either stratified by age or by maturity. Total fat percentage was the only dependent variable which was not influenced by either age or maturity. Age and maturity effect sizes for total body fat percentage indicated practical changes present which did not occur during statistical analysis. The present results indicate poor values when compared to normative data or that of other football playing study populations. Further longitudinal research is required to better understand individual growth rates for youth South African footballers, particularly from the Makana region. Implications of the thesis may determine long term development pathways, while the delayed maturity rate is a critical finding which needs to be further researched.
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  • Date Issued: 2020

The effect of alginate supplementation on the growth, feed utilization, digestive enzyme activity levels, and intestinal morphology of juvenile South African abalone (Haliotis midae) fed formulated feeds

  • Authors: Tlakedi, Thato
  • Date: 2020
  • Subjects: Abalones -- Feeding and feeds -- South Africa , Haliotis midae , Abalones -- Digestive organs , Abalones -- Morphology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/145279 , vital:38424
  • Description: Alginate occurs abundantly in kelp and while a few studies have quantified the effect of kelp inclusion in formulated Haliotis midae feeds, none have researched the effect of alginate inclusion on the growth of abalone fed this feed. Feeding kelp to cultured abalone affects gut structure and modulates gut bacteria, aiding digestion by upregulating enzyme activity. This farm-based experiment compared the growth, feed utilization, digestive enzyme activity levels and intestinal villi structure between abalone (1-year-old, 10 - 20 mm shell length) fed kelp-supplemented (BK) or alginate-supplemented (BA) diets and abalone fed basal (B) and fresh kelp (K) diets for a period of eight months from June 2017 to February 2018. Growth and enzyme activities were also compared between abalone that experienced dietary changes and abalone that remained on their initial diets. The tested diets were: base diet (B, 34% protein), the same base diet supplemented with fresh minced kelp (0.90% kelp [dry mass, equivalent to 0.20% alginate]; BK), base diet supplemented with sodium alginate (0.20% alginate; BA) and a fresh kelp diet (K). Alginate or kelp inclusion in a formulated feed had no significant effect on the specific growth rates (SGR), linear shell growth rates (LGR), daily percentage feeding rates (PFR), feed conversion ratio (FCR), percentage mass gain (MG) and condition factor (CF) over the eight month trial period, compared to abalone fed the base diet. In October 2017, four months since the start of the trial in June, all the groups fed formulated feeds showed significantly higher average weight gain (8.42 ± 0.72 g to 8.86 ± 0.63 g) compared to the kelp-fed group (6.68 ± 0.43 g). However, no significant differences in the average weight gain were observed between abalone fed kelp and formulated feeds at the end of this study. Furthermore, there were no significant differences in the FCR and PFR between abalone fed the base or alginate diets and abalone fed the fresh kelp diet. However, the SW diet produced significantly lower FCR (1.00 ± 0.13) and PFR (0.78 ± 0.10%) compared to the kelp diet (10.6 ± 1.40% and 8.12 ± 1.01%, respectively). All formulated diets produced non-significant LGR, MG and CF compared to the kelp diet at the end of this study. Enzyme activity levels were compared between abalone fed the test diets in July and August 2017 and February 2018. There were no significant differences in the average alginate lyase specific activity levels between abalone fed formulated diets in July and August 2017. At the end of the trial, however, the alginate diet induced significantly higher alginate lyase specific activity levels (4.89 ± 1.64 mg.mg-1 protein) compared to the base diet (1.57 ± 0.98 mg.mg-1 protein), but showed no significant differences compared to the SW (3.78 ± 0.41 mg.mg-1 protein) and fresh kelp-only diets (4.00 ± 0.62 mg.mg-1 protein). The SW diet showed no significant differences in the alginate lyase specific activity levels compared to the base diet. There were no significant differences in the chymotrypsin activity levels between the test diets throughout this study. Alginate or kelp inclusion also had no significant effect on the intestinal structure compared to the base or fresh kelp diets. This was despite a higher degree of variability in microvilli height and width being observed in abalone fed the kelp-only diet, with microvilli visibly wider and longer than in abalone fed formulated feeds. Switching abalone between some diets significantly affected the average weight gain, MG, FCR and PFR, alginate lyase, chymotrypsin and cellulase activity levels compared to abalone kept on their initial diets. The inclusion levels of kelp and alginate used in this study were likely too low to affect abalone growth as higher inclusion levels, particularly of alginate, have been found to improve fish growth. This study concluded that minced kelp and alginate inclusion in a formulated H. midae diet did not affect the SGR, FCR and intestinal morphology, but significantly affected alginate lyase and chymotrypsin activity levels. Furthermore, changes in growth and digestive enzyme activity levels coincided with dietary changes. Consequently, higher inclusion levels, particularly of sodium alginate, and the effect of dietary changes on abalone growth and digestive enzymes must be investigated in future studies.
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  • Date Issued: 2020

The effect of bioslurry effluent on growth and development of swiss chard (beta vulgaris l.)

  • Authors: Dumani, Azile
  • Date: 2020
  • Subjects: Sewage sludge -- Seedlings , Swiss chard -- Seedlings
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48268 , vital:40837
  • Description: Studies were conducted at Döhne Agricultural Development Institute (DADI) (32°31’ 34.077” S; 27°27’ 37.473” E) in Stutterheim, Eastern Cape, South Africa, 2017 and 2018. The objectives of this study were (i) to evaluate the effect of bioslurry effluent on seedling growth of Swiss chard (Beta vulgaris L.), (ii) to study the effect of bioslurry effluent on growth, development and the nutrient content of Swiss chard and (iii) to evaluate the residual effect of bioslurry on biological yield and nutrient content of Swiss chard. Experiment 1 was conducted in a glasshouse using two cultivars (Fordhook giant and Star 1801) seeds planted in 200 cavity trays using Hygromix. The treatments were: control (no fertiliser), 50%Bioslurry, 100%Bioslurry, 200%Bioslurry and the recommended rate of 2:3:4 (30) NPK fertilizer. The experiment was arranged in a randomized complete block design replicated three times. At four weeks after germination, ten seedlings per treatment were destructively sampled randomly to determine shoot height and root length, seedling mass, fresh shoot and fresh root mass, dry mass and nutrient content of leaves. The results showed that fertilization with 100%Bioslurry produced significantly taller seedlings (16.33cm) and shoot height (8.72cm), while the shortest seedlings were obtained from the recommended inorganic fertilizer. Fertilization with 200%Bioslurry and the control treatment produced significantly higher biological yield. compared to other treatments. The interaction between fertilizer treatments, cultivar and season indicated that summer season performed better compared to winter in seedling growth and development, and Fordhook giant fertilized with 100% and 200%Bioslurry was superior compared to Star 1801. Fertilization with 50%Bioslurry resulted in seedlings with higher sodium, while the seedlings grown in the control treatment showed higher copper content. The highest manganese was obtained from the seedlings fertilized with the inorganic fertilizer. In Experiment 2, 10 plots of 4.5m² were established in a greenhouse and were replicated three times, using the same cultivars and fertilizer treatments as in Experiment 1. One seedling was planted per hill at a spacing of 0.25m between plants and 0.5 m between rows and this accommodated 28plants per plot. At 20-day intervals, five plants were randomly selected for data collection until 60 days after transplanting. The cultivar significantly affected growth and biological yield parameters, with Fordhook giant performing better in all the three sampling intervals compared to Star 1801 during summer growing season. Fertilizer application positively affected growth and biological yield parameters and plants treated with 200%Bioslurry and the recommended rate of inorganic fertiliser produced the best results. Experiment 3 was carried out in the same manner as experiment two, except that no fertilizer was applied and the seedlings were planted in corresponding treatment to evaluate the residual effect of bioslurry and inorganic fertilizer. The inorganic fertilizer had the highest residual effect compared to bioslurry. Although not necessarily performing significantly better in terms of the residual effects, the bioslurry showed a good potential as an alternative fertilizer source.
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  • Date Issued: 2020

The effect of integration of affordable/ low cost housing into urban areas on property values

  • Authors: Ngxwashula, Ntomboxolo
  • Date: 2020
  • Subjects: Housing -- South Africa , Urban poor -- Housing -- South Africa Real property -- Valuation -- South Africa Property
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/46838 , vital:39666
  • Description: In the recent years in South Africa after the apartheid era, the government has for the past 25 years been embarking on programmes and policy directives to address the past spatial injustices amongst other things that the apartheid government has left the country with. It is clear that some of the apartheid marks are still to this day evident and challenging to resolve. One of the priority government’s projects is to integrate communities without classifying areas with skin colour, income range etc. Since 1994 the government has developed a lot of legislation and policies in favour of spatial integration of low cost housing and affordable housing within the existing urban fabric. According to COGTA. (2016:22) urban areas in South Africa remain marked by profound social divisions, which stem from apartheid planning and, since 1994, have been reinforced by the uneven growth in land values and limited access by the poor to resources. The growth of the black middle class has resulted in more racial mixing in the (previously predominantly white and middle-class) suburbs, however, very little in working-class and poor areas. Furthermore it is argued that the property and land use status quo undermines access to urban opportunity and reinforces the highly inefficient urban sprawl that is characteristic of South Africa’s urban areas. There has been no substantial land reform and restitution, especially in urban areas, in part because of the importance of the formal property market, which increased significantly between 1994 and 2014. While this growth is essential to the health of rates income for municipalities, it has not addressed the issue of well-located, affordable housing and decent shelter for all. Spatial Integration has been implemented in some parts of the country, however it is evident that there is some resistance towards the concept of spatial integration and the most referred to reason for the resistance is that the integration of low cost or social housing into high income areas will decrease the property values of the existing properties in urban areas. This research aims to study and investigate if property values are affected by the inclusion of low cost housing in existing urban areas and further investigate why there is still resistance to the concept of integration and address any underpinning reasons and provide recommendations. In this study the related literature was reviewed and an empirical study was conducted. The empirical study was conducted using a combination of qualitative and quantitative approaches, referred to as Mixed Method. The research involved the use of questionnaires (Multiple Choice questions and Likert Scale format type of questions), semi-structured interviews and observation done by the researcher. The findings suggest that the following variables influence the resistance towards spatial integration of affordable/low cost housing into urban areas: Increased crime rate, Negative impact on property values, Clutch of different cultures, NIMBY Syndrome (Not in my Backyard), and Aesthetics of low cost/ social housing. The findings of this research may be used for a further research for a doctoral research investigating, more comprehensive detail, each of the identified variables in the perceived resistance towards spatial integration into urban areas framework which is apparent in the review of the related literature. In accordance with the results of this study and the testing of the objectives and sub questions, all variables have a positive influence on the perceived effect of spatial integration onto urban areas. Equally, some of the variables are not perceived to have a direct but an indirect relationship with spatial integration. The results of this research confirms this research questions and reveals two important things that, the concept of spatial integration into existing suburbia does have a negative effect on existing middle to high income properties in proximity to the social houses. Secondly the results reveal that concept of spatial integration of social housing into existing suburbia areas does positively affect the property values of the social housing. According to the definition of Property value which refers to the worth of a piece of real estate based on the price that a buyer and seller agree upon, furthermore the value of a property converges at the point where the forces of supply meet the forces of demand. In other words, the value of a property at any given time is determined by what the market will bear. Through this study it has been discovered that although property valuations for residential properties are conducted by means of a Comparative Method, which basically compares similar properties, it is however evident through this research that demand for properties located in areas where spatial integration has been implemented is very low, which leads to property owners desperately reducing their prices just to sell. Therefore this research concludes that spatial integration does have an impact on property values, though it is not a determining factor in the calculation of property value, it has an indirect impact. This study contributed to the South African property development body of knowledge, by determining the factors influencing the continued resistance towards Spatial Integration of affordable/low income housing into existing urban areas on property values.
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  • Date Issued: 2020

The effect of muscle type and freezing on the evolution of physico-chemical properties during processing of South African biltong and its final textural properties

  • Authors: Ngwendu, Nwabisa
  • Date: 2020
  • Subjects: Biltong Meat -- Quality -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10353/12128 , vital:39154
  • Description: The study investigated the effect of muscle type and freezing on evaluation of mass transfer during processing physico-chemical of South African biltong and its textural properties. In the first experimental phase of this study, mass transfers, physico-chemical and textural properties (hardness, cohesiveness, springiness, and chewiness) of commercially produced biltong from biceps femoris (BF) and semitendinosus (ST) (n=9) were measured. Biltong was dried at 30oC and 40% relative humidity until it had lost 50% of its initial weight. The initial moisture content, water activity (Aw) of BF muscles (74.3% and 0.992) were significantly lower compared those of ST muscles (75.4% and 0.994%). The fat content of BF (2.3%) muscles was higher (P<0.05) than in ST muscles (1.7%). The salt, weight and water gain for the BF muscle were 2.3%, -2.6% and -7.0% respectively and were significantly higher than those of ST muscles which were 2.1, -0.4 and -4.0, respectively. After drying, the moisture content, Aw, and pH were lower in BF (42.2, 0.886 and 5.29) than those of ST muscles (45.1, 0.911 and 5.42). The salt content was higher (P<0.05) in BF muscle than in ST. Among textural properties, hardness was significantly higher in biltong from the BF (233.0N), while the springiness was significantly lower compared to the ST muscle (178.2N). Therefore, it was concluded that the use of different muscles results in variation of biltong physicochemical characteristics. The second experiment investigated the effect of freezing and muscle type on mass transfers, lipid oxidation, physico-chemical and textural properties of biltong. In this experiment, the iii ST muscles were replaced with semimembranosus (SM) muscles. A total of 12 beef muscles were used, with six BF and six SM muscles frozen in a blast freezer at -40 oC till they reached -20oC; then they were transferred to -20oC for 14 days. The thawing loss for the BF and ST muscles was 1.3 and 2.4% respectively, but there were no significant (P>0.05) differences. The protein and salt content were significantly higher in frozen-thawed (24.3 and 0.13%) muscles than in fresh muscle (20.2 and 0.08%); whereas the fat content and pH were lower (P<0.05) in frozen-thawed (5.36) compared to fresh muscles (5.51). Between muscles, the moisture, salt content, and pH were higher in BF muscles than in SM muscles (73.2, 0.12% and 5.49). Aw was affected by the interaction between freezing and muscle type, with frozenthawed SM having lower Aw (0.990). During salting, salt, weight and water gain did not show any differences (P<0.05). There were no major significant differences after salting. There were lower TBARS and pH in frozen-thawed (1.5mgMDA/kg and 5.15) muscles than in fresh muscles (3.3mgMDA/kg and 5.19) as well as in SM muscles (1.8mgMDA/kg and 5.16) than in BF muscles (3.0mgMDA/kg and 5.19). The moisture was significantly lower in frozen-thawed SM (68.1%) than in fresh SM, BF and frozen-thawed BF (69.3,70.5 and 71.7%) after salting. On the final product, the interaction between muscle type and freezing affected the moisture content, TBARS, chewiness and the springiness of biltong, with the biltong from fresh SM (39.8%) having significantly lower moisture content compared frozenthawed BF and ST muscles as well fresh BF muscles (42.8% in average). The TBARS were higher in biltong from fresh BF muscles (5.1mgMDA/kg) compared to other muscles. Furthermore, the chewiness and springiness were higher (P<0.05) in biltong produced from SM frozen-thawed muscles (327.7N and 1.5). The WBSF was higher in biltong from the BF muscles (108.8N) than in the biltong from SM (80.1) but it was not affected by the freezing effect (P>0.05). Freezing did not show any major differences in biltong. iv The third experiment was conducted to determine the effect of freezing African buffalo carcasses on weight loss during salting, physico-chemical and textural properties of biltong. Five muscles (ST, SM, BF, LTL, and RF) were randomly selected from 30 carcasses (15 frozen-thawed and 15 fresh), cut along the grain, traditionally salted and dried at 26oC till they lost 45-50% of their initial weight. The salting weight loss was higher in frozen-thawed muscles (-1.45%) than in fresh muscles (-0.89%). The freezing treatment affected the physico-chemical properties of the biltong. The biltong produced from frozen-thawed muscles showed significantly higher protein and ash (47.6 and 7.6%) compared to fresh (43.9 and 7.1); whereas the moisture, fat, pH and Aw were lower (43.7, 2.1, 0.870 and 5.30, respectively) compared to those of biltong from fresh muscles (45.5%, 2.9%, 0.890 and 5.38). The moisture, pH and fat content were further affected by muscle type. The interactive effect was observed in salt content, with RF frozen-thawed showing higher salt content (8.2%) compared to all other muscles. The hardness and WBSF were significantly higher (P<0.05) in biltong frozen-thawed (204.1N and 135.0N) than in fresh muscles (146.2N and 113.1N). Moreover, the chewiness and springiness were affected (P<0.05) by muscle type, with RF muscle having higher springiness 0.89 and chewiness 171.1N than all the other muscles. Therefore, it can be concluded that freezing buffalo carcasses significantly influenced the quality characteristics of biltong. The fourth experiment studied the effect of drying methods on physico-chemical properties of traditional biltong produced from African buffalo muscles. The BF and SM muscles were randomly selected from 15 fresh carcasses, cut into strips, salted and divided into two batches per muscle. The first batch of each muscle type was dried in the ambient-air drier at 22oC average and the second batch in the cabinet drier at 26 oC till 45-50% weight loss. No differences (P>0.05) were observed in salting weight loss between the drying method and muscle type. The protein content was significantly higher in SM (46%) muscles compared to v BF (43%) but there was no effect (P>0.05) caused by the drying method. The interactions between the muscle type and drying method affected the fat content, with biltong from airdried BF muscles having significant lower (2.1%) fat content. There were no significant differences in other physico-chemical properties of biltong, with moisture content, salt, ash content, Aw and pH being 45.0%, 5.13%, 44.8%, 7.3%, 2.7%, 0.885 and 5.61 on average, respectively. Overall, the findings of the study show that freezing does have a significant effect on the final quality of biltong. However, it can be concluded that a significant effect on the physico-chemical properties of biltong depends on the changes of mass transfers during salting and drying.
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  • Date Issued: 2020

The effect of waste tyre pyrolysis-derived carbon black on the various properties of natural rubber/styrene-butadiene rubber blends

  • Authors: Ketelo, Sisonke
  • Date: 2020
  • Subjects: Rubber chemistry , Rubber Polymers
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/49115 , vital:41602
  • Description: Disposal of waste tyres into landfills is common in developing countries, including South Africa. This behaviour is detrimental to human health as well as other living organisms and the environment itself. There are several recycling methods and processes that have been adopted in various countries to mitigate the situation. These include the recovery of materials such as rubber for re-use; shredding of tyres into small crumb particles for secondary applications in various industries such as civil engineering and the automotive sector; and commonly through heating tyres under a controlled environment to produce oil in a process called pyrolysis. The latter is of interest to the study, with a specific interest in valorization of the process’ resultant char/pyrolysis carbon black. In principle, this study considers the advancement of waste tyre material recovery by finding applications for pyrolysis-derived carbon black (pCB) recovered from waste tyres as it is one of the significant products of pyrolysis. The study involved investigating the effectiveness of pyrolysis-derived carbon black in its ability to improve the properties of natural rubber/styrene-butadiene rubber blends for the conveyor belting industry and other related industries. The pyrolysis-derived carbon black was characterized and compared to commercial grades of carbon blacks on properties such as surface area, thermal stability, heat absorption, structure and morphology using various laboratory techniques such as XRD, XRF, TGA, BET, DSC and SEM. It was found that the properties of the unmodified pCB closely matched those of commercial carbon black grade N660. Through internal mixing, rubber compounds were prepared using 40 phr of pCB and of the selected carbon black grades. Improvements were observed in the mechanical properties of the polymer for application specifications, especially tensile properties and abrasion resistance. Pyrolysis-derived carbon black improved tensile properties to a similar magnitude as a reinforcing carbon black grade and produced similar cure times. Partial replacement of a commercial carbon black grade with pCB of 5 to 20 phr in NR/SBR yielded intermediate results. The unmodified pCB can be used to improve the physical properties of natural rubber/styrene-butadiene rubber blends because it exhibits filler behaviour.
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  • Date Issued: 2020

The effects of elevated atmospheric CO2 on the biological control of invasive aquatic weeds in South Africa

  • Authors: Baso, Nompumelelo Catherine
  • Date: 2020
  • Subjects: Aquatic weeds -- Biological control -- South Africa , Plants -- Effect of atmospheric carbon dioxide on , Atmospheric carbon dioxide -- Environmental aspects
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/140772 , vital:37917
  • Description: There has been a rapid increase in atmospheric CO2 concentration, from pre-industrial values of 280 ppm to more than 400 ppm currently, and this is expected to more than double by the end of the 21st century. Studies have shown that plants grown above 600 ppm tend to have an increased growth rate and invest more in carbon-based defences. This has important implications for the management of invasive alien plants, especially for the field of biological control which is mostly dependent on herbivorous insects. This is because insects reared on such plants have been shown to have reduced overall fitness. Nevertheless, most of the studies on potential changes in plant-insect interactions under elevated CO2 are based on agricultural systems, with only a limited number of these types of studies conducted on alien invasive weeds. However, climate change and invasive species are two of the most prevalent features of global environmental change. Therefore, this also warrants active research and experimental studies to better understand how these systems will be affected by future climates. Thus, the aim of this study was to investigate the effects of elevated atmospheric CO2 on the biological control of four invasive aquatic weeds (Azolla filiculoides, Salvinia molesta, Pistia stratiotes, and Myriophyllum aquaticum). These species are a threat to natural resources in South Africa but are currently under successful control by their biological control agents (Stenopelmus rufinasus, Cyrtobagous salviniae, Neohydronomus affinis, and Lysathia n. sp.). To achieve this, the selected plant species were grown in a three-factor experimental design in winter (CO2 X nutrients X herbivory), and another two-factorial design in summer (CO2 X herbivory). Atmospheric CO2 concentrations were set at ambient (400 ppm) or elevated (800 ppm), as per the predictions of the IPCC. As per my hypothesis, the results suggest that these species will become more challenging in future due to increased biomass production, asexual reproduction and a higher C: N ratio which is evident under high CO2 concentrations. Although the biological control agents were in some instances able to reduce this CO2 fertilisation effect, their efficacy was significantly reduced compared with the levels of control observed at ambient CO2. These results suggest that additional biological control agents and other management methods may be needed for continued control of these invasive macrophytes, both in South Africa and further afield where they are problematic.
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  • Date Issued: 2020

The effects of vascular targeted bi-functionalized aunps on hepatic lipid metabolism of a diet-induced rats

  • Authors: Singo, Dakalo Gladwell
  • Date: 2020
  • Subjects: Bile acids
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/47072 , vital:39780
  • Description: Introduction: Obesity is a metabolic disease in which the accumulation of excessive fat in the adipose tissue may interfere with the normal maintenance of a healthy state. However, there is only a limited number of drugs approved for the treatment of obesity. For this purpose, target therapies are receiving more attention as a preferred treatment to reduce the burden of chronic diseases which are associated with the current strategies. Nanotechnology is a highly promising field that offers a nanotechnology-based drug delivery system as a novel means of solving issues associated with the toxicity of conventional anti-obesity drugs. Vascular targeted nanotherapy (targeted bi-functionalized nanoparticles) as a strategy that can overcome the current available anti-obesity drugs. Aim: This study sought to understand the effects of nanotherapy in the hepatic lipid metabolism and secretion of bile acids Research focus: The effects of gold nanotherapy on the bile acid biosynthetic enzymes, transporters and lipogenic enzymes of rats that were on a high fat diet. Conclusion: The study shows low expression in the majority of genes responsible for bile acid synthesis and a lipogenic pathway; therefore, the effects of nanotherapy exhibit low toxicity in the hepatic lipid metabolism.
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  • Date Issued: 2020

The exploration of ARF1 screening assays to determine the drug status of ARF1 in cancer and malaria

  • Authors: Ntlantsana, Apelele
  • Date: 2020
  • Subjects: ADP ribosylation , Golgi apparatus , Guanosine triphosphatase , G proteins , Malariotherapy , Malaria -- Research , Cancer -- Chemotherapy , Malaria -- Chemotherpay
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/167232 , vital:41458
  • Description: ARF GTPases are key regulators of the secretory and endocytic pathways. ARF1 is involved in the secretory pathway. ARF1 has been implicated in the endoplasmic reticulum to Golgi transport, function of the Golgi apparatus and transport from the trans-Golgi network to endosomes. ARFs cycle between active GTP-bound and inactive GDP-bound conformations. GDP/GTP cycling is regulated by large families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). ARF GEFs facilitate the activation of ARFs by mediating the exchange of GDP for GTP, while ARF GAPs terminate ARF function by stimulating the hydrolysis of the terminal phosphate group of GTP. Based on existing evidence gained from gene manipulation and cell biological investigations, ARF1 has been shown to be fundamentally important for cancer cell proliferation and metastasis and may be a promising target for the development of anti-cancer drugs. Additionally, the conservation of ARFs in eukaryotic organisms leads to an interesting question of whether a single drug target can be used to target multiple diseases. In this case, can a human cancer drug employed for cancer therapy be used in anti-malarial drug therapies? To confirm the drug target status of ARFs using chemical validation experiments, novel inhibitory compounds are needed. This requires the development of complex in vitro protein- protein interaction assays that can be used to screen chemical libraries for ARF GTPase inhibitors. In this study, we developed a fluorescence resonance energy transfer (FRET) assay and a novel in vitro colorimetric plate-based assay to detect the activation status of truncated human and Plasmodium falciparum ARF1. In the case of the FRET assay, active (GTP-bound) and inactive (GDP-bound) ARF1 could be distinguished with Z-factor values >0.5, suggesting that further development of the assay format to identify GEF and GAP inhibitors may be feasible. In the case of the colorimetric assay, robust signals could be detected and the assay was useful for detecting the activation status of ARF1. However, although the activation of ARF1 by the Sec7 domains of the BIG1 and ARNO was detectable, signals were not robust enough to employ in screening campaigns.
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  • Date Issued: 2020

The Geography of Inequality in Port Elizabeth : Post-apartheid Trends

  • Authors: Mc Arthur, Brogan Erin
  • Date: 2020
  • Subjects: Equality -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48478 , vital:40880
  • Description: This study aims to identify post-apartheid trends of inequality within Port Elizabeth, by analysing the spatial distribution of social well-being from 1996 to 2011. The spatial distribution of social well-being highlights the geography of inequality within Port Elizabeth, focusing on social indicators as a measure of social well-being. Mapping of these social indicators illustrates various levels of social well-being throughout Port Elizabeth based on the formulation of social indicators, application of these social indicators to census data, data processing and mapping. This results in the mapping of poverty, employment, education and standard of living for the census years of 1996, 2001 and 2011. From the mapping process, trends of social well-being and the associated inequality are illustrated and analysed, while providing insight into the progress of social well-being within a South African city. The findings of this study suggest that social well-being has incurred changes over time which have aided in the improvement of social well-being throughout Port Elizabeth. This improvement is marked by the relative increase and decrease of selected social indicators and their interrelated nature. The various social indicators, although focused on different datasets, highlight similar patterns of progress throughout their spatial distribution over time. As such, similar patterns of inequality can be noted throughout Port Elizabeth for various social indicators. Based on these similarities and the trends identified within the spatial distribution of inequality in Port Elizabeth, a progression towards a more even distribution throughout the study area was noted from 1996 through to 2011.
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  • Date Issued: 2020

The impact of agricultural infrastructure on rural livelihoods in KwaZulu-Natal

  • Authors: Mankahla, Sipesihle Qukeza
  • Date: 2020
  • Subjects: Agriculture -- Economic aspects , Agricultural development projects -- South Africa -- KwaZulu Natal , Project management
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/46141 , vital:39508
  • Description: The purpose of the study was to investigate the impact of agricultural infrastructure on rural livelihoods of kwaZulu-Natal. The main objective of the study is to look into the ways in which rural infrastructure can improve the livelihoods of kwaZulu-Natal farmers. Government programmes such as agri-parks, one household-one hectare and cooperative funding, when implemented according to their objective, can improve the implementation of infrastructure development in rural areas of kwaZulu-Natal. The objectives of the study were achieved by reviewing the literature relevant to the topic. Data was sourced from primary and secondary sources. A qualitative method was used as the qualitative approach has been considered to be the most appropriate method in achieving research objectives. This approach puts emphasis on the meanings and experiences as found in the study of Lincoln and Denzin. This approach best describes events, opinions and views without the use of data in the form of numbers; rather it provides textual data that gives an insight into the occurrence being studied. The developments in agriculture would not be sustainable without developing the rural areas and addressing the issues of poverty and enhancing investment capacities of the resource-poor farmers. The linkage of infrastructure to positive economic development cannot be denied. Agricultural infrastructure is infrastructure such as irrigation, rural electrification, roads, and markets in close coordination with institutional infrastructure. There is a long list of infrastructure assets that affect rural development. There is basic agricultural infrastructure which forms the foundation for agricultural economic development of rural livelihoods. This infrastructure includes transport networks, access to water and livestock agricultural infrastructure. Thus, the study sought to establish the impact of existing agricultural infrastructure on agricultural economic development and improvement of rural livelihoods in kwaZulu-Natal. The study revealed that the rural farmers in this province were affected and limited by poor road infrastructure and that access to suitable water for irrigation was far from ideal. As a result, the sector is hindered and does not perform to its full potential and this slows economic development and negatively affects rural livelihoods.
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  • Date Issued: 2020

The impact of discounting fees by civil engineering consultants

  • Authors: Siqiti, Khulile
  • Date: 2020
  • Subjects: Consulting engineers , Consultants Civil engineering , Project management
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/47246 , vital:39836
  • Description: The study provides insight into the views and perceptions of consulting engineers on the discounting of professional fees. The purpose of the research was to determine the impact of discounting professional fees in the civil engineering profession and ultimately potential ways in which the civil engineering profession could improve business sustainability. The study included a review of literature, which was utilised to develop a questionnaire. A total of 26 practicing consulting engineers, who are members of Consulting Engineers South Africa (CESA), and represented small, medium and large consulting engineering firms, participated in the questionnaire survey. The questionnaire investigates the respondents’ perceptions on the impact of discounting professional fees in the civil engineering profession and the amount of discount offered as well as the reasons for discounting fees. The results show that the practice of discounting professional fees is widespread, affecting small, medium and large consulting firms. The results also indicate that prevailing market conditions in civil engineering profession are the primary reasons why consulting engineers offer discounts on fees. Respondents agreed that projects are awarded to the lowest bidder during tender process. Respondents also agreed that experienced engineers are allocated less time on projects to manage project costs. The findings suggest that discounting of professional fees is a great concern that needs to be addressed in order to attain profession business sustainability. It is suggested that the Engineering Council of South Africa (ECSA) should regulate the fee structures and ensure that all professionals, whether employed in the public or private sector, understand the basic finances on running a professional consultancy to deliver a service.
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  • Date Issued: 2020

The influence of anthropogenic and environmental covariates on the habitat use and density of sympatric carnivores, Limpopo Province, South Africa

  • Authors: Faure, J Philip B
  • Date: 2020
  • Subjects: Carnivorous animals -- South Africa -- Limpopo
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48302 , vital:40840
  • Description: Carnivores are declining and undergoing substantial range contractions which have largely been attributed to anthropogenic related. Globally, there has been an increase in establishing protected areas for species conservation. However, protected areas may not always effectively conserve all biodiversity, where some areas are too small for viable populations of wide-ranging species, such as leopards Panthera pardus, spotted hyaenas Crocuta crocuta, and brown hyaenas Parahyaena brunnea. The importance of privately-owned areas are gaining increasing recognition for their role in conserving species, and ecosystems. Though such areas may provide key opportunities for the conservation and persistence of biodiversity, little attention (with regards to species conservation planning) is given to these areas. Furthermore, large carnivore populations increasingly have to share the landscapes with humans as the global human population increase. Though anthropogenic impacts can be limited within protected areas, human activities on privately-owned farmlands are mostly dictated by economic activity to sustain human presence (often leading to humancarnivore conflicts). Platjan (South Africa) is one such area. It comprise a matrix of agricultural practices and land-use types, dominated by humans. Consequently, it presented an ideal landscape to investigate how humans and carnivores coexist. Spatial capture-recapture modelling suggest stable populations manifested through low densities for leopards, spotted hyaenas, brown hyaenas, and Africa civet Civettictis civetta within the study area. Densities of the focal species were more similar to what has been found in more arid environments. Though it should be noted, that population fluctuations are common in nature, and this study only provide a brief snapshot of the population. Nonetheless, it provides baseline carnivore density estimates for the area. Single-season, single-species occupancy modelling was used to determine the influence of anthropogenic variables on species probability of site use. Results suggested that leopards and spotted hyaenas avoided crop fields (possibly due to higher human activity in these areas). Whereas black-backed jackal Canis mesomelas were positively influenced by the proportion of survey sites containing human infrastructure (possibly due to additional food sources provided by human presence). The covariates did not suggest any effect on brown hyaena and African civet probability of site use, which may be explained by temporal niche partitioning between the species and humans. Kernel density estimation and selectivity ratios revealed that all carnivores were predominantly crepuscular-nocturnal, with the exception of brown hyaenas which were strictly nocturnal. Among the focal species, brown hyaenas and African civets had the lowest temporal overlap with humans, which may explain why they weren’t affected by any of the anthropogenic variables. Whereas, jackal had the highest overlap, supporting a notion that they may be more tolerant of human presence than the other study animals. Overall, it seems that carnivores are able to coexist with humans on privately-owned farmlands through temporal niche partitioning, but manifest at rather low densities. Nonetheless, this study adds to the current understanding of human-carnivore coadaptation, and provides the first carnivore density estimates for the Platjan region.
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  • Date Issued: 2020

The influence of the integration of local knowledge during chemistry hands-on practical activities on grade 8/9 learners’ attitude towards science

  • Authors: Ngqinambi, Akhona
  • Date: 2020
  • Subjects: Science -- Study and teaching (Secondary) -- South Africa , Science teachers -- South Africa , High school students -- Attitudes , Communities of practice -- South Africa , Science clubs -- South Africa , Science projects -- South Africa , Constructivism (Education) -- South Africa , Educational counseling -- South Africa , Local knowledge
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/144724 , vital:38373
  • Description: With every passing year, there is a decrease in the number of learners pursuing science degrees after completion of grade 12. One of the main reasons for this is the negative attitude that high school learners have towards science learning and science as an entity. The Natural Sciences curriculum suggests the use of local knowledge to introduce the usefulness and the relatability of science to learners. This study is an intervention that seeks to ascertain the influence that local knowledge has on the attitudes of grade 8/9 learners when integrated into their chemistry hands-on practical activities. The study was informed by Vygotsky’s social constructivist theory and Wenger’s community of practice theory. Grade 8/9 learners from four high school science clubs did three local knowledge integrated experiments based on acids and bases. The learners completed pre- and post- surveys and were interviewed about their experiences. Volunteers at the science clubs were also interviewed. Excel was used to deductively analyse quantitative data. On the other hand, an inductive-deductive thematic approach was used to analyse the qualitative data. The findings of the study showed a divergence of qualitative and quantitative methods. The quantitative data showed that there was a slight decrease (but not statistically significant) in the attitude of the learners after engaging in chemistry hands-on practical activities into which local knowledge had been integrated. On the other hand, the qualitative data showed that there was a positive shift in the learners’ attitudes after they had been engaged in the chemistry hands-on practical activities. Additionally, the findings of the study revealed that the integration of local knowledge promotes conceptual understanding and improves the performance of the learners. This study thus recommends that local knowledge should be integrated into the grade 8 and 9 learners’ curriculum to enrich and promote contextualized science for learners. Additionally, the integration of local knowledge would promote conceptual understanding and spark interest and motivation in learners to pursue science-related careers.
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  • Date Issued: 2020

The jackal as a mesopredator : dietary response to an apex predator and role as an endozoochore

  • Authors: Favaretto, Bianca Sashika
  • Date: 2020
  • Subjects: Jackal buzzard
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48313 , vital:40841
  • Description: Interactions between apex predators, mesopredators and their impacts on trophic dynamics have been well documented. However, the influence of apex predators, through the provision of carrion, on the foraging ecology of African mesopredators is poorly understood. To investigate such resource supplementation by apex predators for mesopredators, the black-backed jackal Canis mesomelas, a generalist mesopredator, was used as a model species to improve our understanding of this topic in South African ecosystems. To do this, I compared the diet of jackal at replicated sites with and without cheetah in the eastern Karoo, South Africa. Scat samples were macroscopically categorized into six broad dietary categories: mammal, reptile, bird, fruit, forage and insect. Mammalian prey was further identified to species and grouped into six functional dietary categories: carnivore, large ungulate, small ungulate, small mammal, and unknown mammal. Jackal diets were dominated by mammal prey, with significant differences in the biomass and frequency of occurrence of mammals by jackal at sites with cheetah and without cheetah. Mammal consumption, showed limited variation amongst seasons. Resource supplementation provided by predator derived carrion is an important factor influencing jackal foraging ecology. The emergent hypothesis that jackal may show demographic responses (increased fecundity, survival, density) to this supplementation needs to be tested. This study also provided an opportunity to investigate the potential role of jackal as an endozoochore. Jackal consume fruits and their seeds, yet to our knowledge, an investigation into their seed dispersing abilities is yet to be investigated. This study assessed the viability and germination capacity of ingested seeds extracted from jackal scat samples using the tetrazolium tests and germination trials. Seed viability and germination of all three species (Grewia occidentalis, Pappea capensis and Diospyros lycioides) were significantly lower than uningested seeds. These results suggest that jackal gut passage is acting severely on ingested seeds. This study represents a novel investigation into differences in jackal diet in sites with and without cheetah as well as the role jackal play in endozoochory, contributing to improved understanding of the ecological role of jackal.
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  • Date Issued: 2020

The past meets the present: exploring the biogeography of extant plecoptera of South Africa with reference to ancient middle permian fossil forms from the Onder Karoo locality near Sutherland

  • Authors: Kirkaldy, Benjamin Puleng
  • Date: 2020
  • Subjects: Stoneflies, Fossil -- South Africa -- Northern Cape , Palaeopteron -- South Africa -- Northern Cape , Stoneflies -- Evolution , Insects, Fossil -- South Africa -- Northern Cape , Paleoentomology , Paleoentomology -- South Africa -- Northern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/165755 , vital:41278
  • Description: The Onder Karoo fossil locality near Sutherland, Northern Cape, recently yielded an unprecedented diversity of middle Permian insects, which were preserved in deposits of an aquatic lake margin system, in the Lowermost Abrahamskraal Formation. A large number of Plecoptera (stonefly) specimens were found, and this study represents an in-depth analysis of these species in the context of plecopteran evolution. A significant contribution to current knowledge of the Plecoptera from the middle Permian to the present has been made, utilizing a combination of fossil and phylogenetic evidence to better understand the origins, evolution, diversity and biogeography of the stoneflies. Three new plecopteran species have been described from the Onder Karoo locality, which is recognized here as the first Lagerstätte of its kind in Gondwana. Possible ecological links and relationships with the plecopterans described here have been suggested, using extant Plecoptera as analogues. An in-depth, fossilcalibrated, dated phylogeny of the Plecoptera was completed, using representatives from all three dominant lineages, the Antarctoperlaria, Systellognatha and the Euholognatha. This provides strong support for the monophyly of the Notonemouridae and the Antarctoperlaria, however the monophyly of Systellognatha and Euholognatha was not supported. The Notonemouridae were found to represent an earlier divergence than previously believed, forming a sister group to the remaining Plecoptera. Through a combination of fossil and molecular evidence, strong support was found for the current distribution of the Plecoptera worldwide being attributable to vicariance caused by the rifting of Pangea, and subsequently Gondwana and Laurasia, and long range dispersal. The focussed effort to include Southern Hemisphere stoneflies throughout this study has been a valuable step in reducing the Northern Hemisphere bias which currently dominates plecopteran research and has assisted in opening the way for future research into this important group on a global scale.
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  • Date Issued: 2020

The profile of local hunters in South Africa

  • Authors: Du Plessis, Madelaine Patricia
  • Date: 2020
  • Subjects: Hunters -- Economic conditions -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48324 , vital:40847
  • Description: The South African hunting industry, but more specifically local hunting, is regarded as one of the key sectors within South Africa’s wildlife industry – not only for the significant economic contribution it makes, but also from an equally vital conservation point of view. Despite this, local hunters are neglected in the sense that hunting accommodation and hunting packages provided by the majority of game ranches mainly focus on accommodating trophy hunters. This study investigated the profile of local hunters in South Africa. The objectives of this study were the following: establishing the factors which determine the profile of local hunters and then comparing the results to existing information, as well as identifying the economic contribution local hunters make towards South Africa’s economy. The study commenced with a literature review of existing research on the local hunting industry and on the profile of local hunters. Thereafter, a self-administered questionnaire was developed and conducted amongst active local hunters via the CHASA hunting confederation website, by means of which the primary data for the current study were collected. The study concluded that the profile of the South African local hunter has undergone slight changes from what previous research had established. This was attributed to several external as well as internal factors. The current research would assist hunting farms in approaching the local hunting sector with up-to-date information in order to accurately tailor their packages and marketing in line with the evidence presented in this dissertation regarding the changes in the profile of the South African local hunter.
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  • Date Issued: 2020

The role of elephants in Hluhluwe-iMfolozi Park: Perceived versus measured effects on woody vegetation

  • Authors: Mbongwa, Siphesihle
  • Date: 2020
  • Subjects: Woody plants -- Environmental aspects
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48467 , vital:40879
  • Description: Elephants were successfully reintroduced into the 900 km2 fenced Hluhluwe-iMfolozi Park (HiP) from 1981 onwards and their population has increased exponentially since. Their initial reintroduction was motivated by the need to control bush encroachment and to maintain ecosystems such as grassland and open woodland, and to restore ecological processes offered by elephants. The subject of the HiP elephant population and their impact on vegetation in the Park has become controversial; with some concerns being raised that the population is too high and is negatively affecting the vegetation. An absence of a vegetation monitoring programme in protected areas with elephants creates uncertainty leading to an ‗elephant impact‘ debate. This study aimed to compare the perceptions of stakeholders regarding the issue of elephant impact in HiP with measured elephant impact on the vegetation in the Park. The perceptions and concerns of stakeholders regarding the effects of elephants on vegetation in HiP were investigated using a questionnaire. Stakeholders reported that elephants and fire were the main factors shaping vegetation change in HiP over the past decade. Sclerocarya birrea, Senegalia burkei and Schotia brachypetala were reported as the most negatively affected species. Also reported that they are concerned about the effects of elephants on the number of tall trees in the park, tree mortality and elephant‘s effect on rare indigenous vegetation. Most interestingly, the results showed that the groups of stakeholders had different perceptions of the level of elephant impact on the vegetation in the park; except for researchers and tourists whose were not significantly different from each other. Managers had the most respondents that reported that the level of elephant impact is unacceptable, while most researchers and tourists reported that the level of elephant impact is at an acceptable level. Vegetation plots that had been surveyed in 1999, 2003 and 2007, were resurveyed in this study during 2017 to assess elephant impact on vegetation over time. Comparison between the years sampled showed that there was a decrease in the density of tall trees, while the density of trees in 0.5-2 and 2-4 m height classes increased over the same period. Elephants had a strong preference for utilizing tall trees (>4 m) and a strong avoidance for trees in the height range from 0.5-2m tall (Jacobs selection index 0.56 and -0.69, respectively). This trend was apparent for all sample periods. In addition, elephants also showed a strong preference for some rare species including S. brachypetala and Sideroxylon inerme. Between 1999 and 2017, the density of preferred species has decreased while the density of avoided species has increased. I conclude that elephants are having a noticeable impact on the vegetation at HiP by changing vegetation structure to a shrub dominated vegetation, and causing a shift in species composition towards avoided species. The findings of this study show that the perceptions of stakeholders on the effects of elephants and the level of elephant impact on vegetation match the results from measured elephant impact - vegetation survey. However, Thresholds of Potential Concern (TPCs) should be outlined in the elephant management plan and are required to determine whether the levels of elephant impact at HiP have exceeded an acceptable level or not. This study conforms to previous research that an uncontrolled elephant population can have substantial impacts in fenced reserves. This study shows the importance for long-term and continuous vegetation monitoring programme to obtain reliable data to determine trends in vegetation changes over time.
  • Full Text:
  • Date Issued: 2020
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