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Investigating how the use of visual models can enhance the teaching of common fractions for conceptual understanding to Grade 8 learners

  • Authors: Katenda, Aune Kashikuka
  • Date: 2019
  • Subjects: Fractions -- Study and teaching (Secondary)-- Namibia , Mathematics -- Study and teaching (Secondary)-- Namibia , Information visualization , Visual learning -- Case studies
  • Language: English
  • Type: text , Thesis , Masters , MEd
  • Identifier: http://hdl.handle.net/10962/96746 , vital:31314
  • Description: The intention of this study was to explore how selected mathematics teachers used visual models to improve the teaching of common fractions for conceptual understanding to Grade 8 learners as a result of an intervention programme. This research study is part of the VIPROmaths project which seeks to research the effective use of visualisation processes in the mathematics classroom in South Africa, Namibia, Zambia, Switzerland and Germany. This study which adopted a case study of teachers in Khomas Region, Namibia, is informed by constructivist learning theory. The study is situated within the interpretive paradigm and a multi-phase mixed method research approach was used. It focussed on analysing the use of visual models when teaching fractions namely: area model, number line model and a set model. The data were collected through survey questionnaires, observation and recall interview. The survey was conducted with the forty three mathematics teachers, from twenty secondary schools in Khomas region. The survey gave an overview of the nature and the use of visual models in schools. Three teachers purposively selected from the survey participated in the intervention program and were observed while teaching and interviewed after their teaching. Data were qualitatively and quantitatively analysed. The findings of this study reveal that visualising fractions is one of the methods that can improve both teaching and learning by providing concrete evidence of otherwise abstract ideas and concepts. The teachers highlighted that models themselves guide learners through to the answer, as compared to working out solutions using symbols only. They further indicated that visual models improve learners’ motivation, enhances understanding of fractions and encourages full participation of learners in the lesson. The study also found that use of visual models encouraged participation and it also boosted learners thinking capability. Teachers in this study preferred to use the area model as they found this model easier and more user-friendly in comparison with the number line and the set models. Teachers did not use the set model because of its complexity. This study concludes that the use of visual models can help enhance the conceptual teaching and understanding of common fractions. It is hoped that the study contributes towards improving the quality teaching and learning of fractions in Namibia. Furthermore, it informs the teacher-training institutions in Namibia to integrate the use of visualisation in their training programmes to promote conceptual understanding of mathematics.
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Investigating mathematical proficiency testing in Namibian school high stakes mathematics examinations: an exploratory study

  • Authors: Ndjendja, Elizabeth
  • Date: 2019
  • Subjects: Education and state -- Namibia , Educational tests and measurements -- Namibia , Mathematics -- Curricula -- Namibia , Mathematics -- Study and teaching -- Namibia , Namibia. Ministry of Education -- Examinations
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/92887 , vital:30759
  • Description: The Namibian government has put processes in place to continuously improve its education system in line with educational development in the world. The education reform efforts are administered and coordinated by the Ministry of Education, Arts and Culture. At the centre of these reform efforts are curriculum policy documents and subject syllabuses with the intention of improving the teaching and learning process in the classrooms. These reform efforts appears to overlook the positive influence high stakes assessment has on the teaching and learning process. The study reported in this thesis was designed to investigate the feasibility of assessing separate elements of mathematical proficiency in the high stakes Mathematics assessment in Namibia. The study was designed as a developmental, exploratory research that collected and analysed both qualitative and quantitative data in order to respond to issues raised by five specific research objectives. The data collected enabled the adaptation of some assessment tools in order to distinctly assess selected mathematical proficiency categories. The results further indicated that the envisaged proficiency assessment system could be used to characterise the examination question papers and revealed insights into the conceptualisation of the current assessment system. The results further indicated the visible distinguishability of different elements of proficiency through the developed tools and the learners’ responses to the NSSCO examination. Finally, constrains and affordance which the original assessment system has in relation to the developed system were revealed and addressed. In closing, the research suggested changes and possible adaptation of assessment tools to ensure the proper assessment of mathematical proficiency aspects through high stakes assessment. Immerging issues that needed further research were also highlighted.
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Investigating the linguistic effectiveness of early reading schemes in isiXhosa: a phonological and orthographical analysis of three isiXhosa Grade 1 graded reader series

  • Authors: Katz, Jennifer L
  • Date: 2019
  • Subjects: Education, Elementary -- South Africa , Literacy -- South Africa , Xhosa language -- Readers , Native language and education -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/92798 , vital:30748
  • Description: Literacy in South Africa is in crisis. Inadequate learning and teaching materials, extensive curriculum changes, under-resourced schools and under-qualified teachers are all contributing factors to an alarming situation. Grade 1 African language reading schemes in South Africa are failing to provide young children with the necessary and appropriate practice required to facilitate home language literacy acquisition (NEEDU 2013). A detailed analysis of three isiXhosa Grade 1 graded reader series will show the short-comings of texts translated from English with no cognisance of isiXhosa phonic structures and little appreciation for the agglutinative nature of Nguni languages. Formulating a new, effective approach to the development of African language readers to facilitate reading literacy is urgent and of national importance. The innovative phonics-based methodology, as well as an appropriate instructional level used to develop the Vula Bula Grade 1 isiXhosa readers appears to be a viable blueprint for the development of early readers that can effectively help to ameliorate current deficient literacy levels in African languages. This research thus combines applied linguistics with literacy materials development.
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Investigating the nature of grade six after school mathematics club learners’ shifts in mathematical number sense and procedural fluency

  • Authors: Baart, Noluntu Via
  • Date: 2019
  • Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa -- Case studies , Numeracy -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MEd
  • Identifier: http://hdl.handle.net/10962/96825 , vital:31326
  • Description: A wide range of research locally points to intermediate phase learners having extremely weak basic number sense resulting in the dominance of inefficient strategies for calculations with the four operations, irrespective of the number range. The grade six Annual National Assessments (ANA) diagnostic reports for 2012 to 2014 also point to errors and misconceptions that tend to dominate learners’ computations in the four basic operations; such errors are often attributed to the use of either tallies or incorrectly applied mathematical procedures. Having the above context in mind and following informal conversations with teachers in the Uitenhage Education District, five teachers expressed an interest in running the afterschool mathematics clubs based on the South African Numeracy Chair (SANC) project model. The SANC project team ran workshops in April, May and June 2016 with nine teachers (five as facilitators and four others as co-facilitators in five different club sites) in which teachers were provided with key resources for use in their clubs. Fifteen club sessions ran in each club with grade six learners across the 2nd and 3rd terms. These clubs form the empirical field for this research, which aims to investigate the nature of learners’ evolving number sense, procedural fluency and teachers’ experiences of working with learners in the club space. The unit of analysis in this study is both the shifts evident in learners’ number sense and procedural fluency as a result of participating in the clubs and the teacher’s experiences of working with learners in those clubs as club facilitators. A social constructivist perspective of learning guides this study. Especially Vygotsky’s (1978) notion that cognitive development stems from social interactions and guided learning within the Zone of Proximal Development (ZPD) of children, guided by more knowledgeable others. Furthermore, Kilpatrick et al.’s (2001) strands of mathematical proficiency provide the conceptual frame with a particular focus on procedural fluency and number sense. A mixed method approach to data collection was used. Quantitative data has been drawn from learner’s scores on pre- and post- assessments on four basic operations. Visual progression spectra have been adopted from the Pushing for Progression (PfP) Programme which is an intervention Programme developed by the SANC project for club facilitators. They provide explanations of learner progression trajectories and how to analyse learner methods. Qualitative narratives were drawn from learner progression data, as well as teacher post club questionnaires and one-to-one teacher interviews. The findings of this research suggest that learner workings when used in conjunction with visual progression spectra can provide important clues to researchers and teachers. This in turn contributes to an understanding of where learners are in their mathematical learning and gives ideas for how to support learners to progress using more flexible methods of calculation, particularly for poor performing learners. Included, is the discussion of the effectiveness of the club space to enable such shifts and improve learner flexibility, fluency and performance as displayed in learner methods and scores of the pre- and post- assessments. The teachers’ observations about the relaxed atmosphere in the club space, small sized groups, learning through play with co-members may have enabled the shifts in procedural fluency and number sense in club learners. Additionally, implications of the study are discussed, and tentative recommendations are made for the DBE to consider.
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Investigating the role of extension officers in supporting social learning of rainwater harvesting practices amongst rural smallholder farmers in Nkonkobe Local Municipality, Eastern Cape

  • Authors: Sithole, Phindile Nomfundo
  • Date: 2019
  • Subjects: Water harvesting -- South Africa -- Eastern Cape , Rainwater -- South Africa -- Eastern Cape , Water-supply, Agricultural -- South Africa -- Eastern Cape , Water-supply, Rural -- South Africa -- Eastern Cape , Agricultural extension workers -- South Africa -- Eastern Cape
  • Language: English
  • Type: text , Thesis , Masters , MEd
  • Identifier: http://hdl.handle.net/10962/96757 , vital:31316
  • Description: Water is essential for food production, however South Africa’s water is already under pressure due to increasing population, food demand, and climate change, amongst other factors. Over the past years, there has been increasing demand for agricultural water use for food production due to these factors. Rainwater harvesting and conservation (RWH&C) for food production is one of the most promising approaches to address increasing demand of water. The Rhodes University Environmental Learning Research Centre have led a project with the Water Research Commission (Project No. K5/2277) focusing on the dissemination of RWH&C practice knowledge that involves some of the extension services in the Nkonkobe Municipality in the Eastern Cape, called the ‘Amanzi [Water] for Food’ project. While extension services were included in the project, the wider role of extension services in ‘disseminating’ RWH&C knowledge amongst farmers is not clear, a problem which provides the focus for this research, especially since there are changes in the designated role of extension services to become more responsive and reflexive in relation to farmers emerging needs, and in response to wider issues such as climate change and water scarcity. In general, there is agreement that the role of extension is to be active within the farming community, to facilitate social interactions and collaborative processes that often focus on activities that are intended to find, assess, interpret and adapt information, knowledge and evidence that are suitable for farmer’s needs. Extension should also be available to identify arising issues that the farmers experience that can be solved by the use of research knowledge. However, little is known with regard to whether extension officers are taking up this role effectively, especially in relation to RWH&C knowledge. Using document analysis, semi-structured interviews, field-based observations and focus group discussions, this research seeks to demonstrate the role of extension services in facilitating and supporting social learning of RWH&C practices amongst rural smallholder farmers for improved food security. It provides insight into the way in which extension officers are able to facilitate social learning using RWH&C knowledge, and the issues that affect the adoption of social learning approaches to extension support related to RWH&C knowledge uptake and dissemination.
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Investment-grade or “junk” status: do sovereign credit ratings really matter?

  • Authors: Slabbert, Adriaan
  • Date: 2019
  • Subjects: Credit ratings , Rating agencies (Finance) , Developing countries -- Economic conditions , Developing countries -- Foreign economic relations
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/97067 , vital:31393
  • Description: Credit ratings play a well-established part in modern financial markets, reducing asymmetric information between investors and borrowers. In particular, sovereign credit ratings allow the world’s lesser-known economies to access a wider pool of international capital, while simultaneously allowing international investors to access a more diverse set of investment opportunities. The importance of sovereign credit ratings in terms of the cost of government debt in developing nations was observed. The relationship between sovereign credit ratings and average bond spreads over the time period spanning 2006 – 2017 was examined in 25 emerging economies. Regression analysis in the form of fixed-effects and random-effects models was used to determine the impact of changes in sovereign credit ratings on the cost of sovereign debt, controlling for certain macroeconomic factors. It was concluded that sovereign credit ratings are relevant in helping to determine the cost of sovereign debt for developing economies, but that they are not the only factor considered by global markets. The thesis therefore recommended further research into the factors affecting the cost of sovereign debt as well as further refinements to the methodologies that ratings agencies use to assign ratings.
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Job creation and income generation in the cultural and creative industries: a case study of the shweshwe sewing industry

  • Authors: Mapuma, Aviwe Simbonge
  • Date: 2019
  • Subjects: Textile industry -- South Africa -- Eastern Cape , Clothing trade -- South Africa -- Eastern Cape , Sewing -- South Africa -- Eastern Cape , Job creation -- South Africa -- Eastern Cape , Textile manufacturers -- South Africa -- Eastern Cape , Textile fabrics , Income -- South Africa -- Eastern Cape
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/122948 , vital:35378
  • Description: Worldwide, there has been a growing realisation of the importance of Cultural and Creative Industries as a driving force for employment creation, income generation and economic growth. Therefore, there is a need in South Africa to study and understand these industries setting, and business environment. Shweshwe is a unique local fabric produced by Da Gama Textiles in the Eastern Cape province of South Africa. This fabric is used by many micro-enterprises as an input to make clothes and other items for traditional cultural celebrations and ceremonies. This study is about the micro-enterprises who use South Africa made textiles (i.e. shweshwe textile) as business input. More specifically, it looks at employment creation and income generation opportunities of the micro-enterprises that use shweshwe textile as an input. These micro-enterprises and shweshwe production are being threatened by the rising influx of cheaper ready-made imported clothes that mimic the shweshwe designs and colours, in some cases, the logo as well. This study also plans to estimate the size and discover the attributes of the micro-enterprises that use shweshwe as an input in their businesses in South Africa, in order to estimate the impact of the counterfeit shweshwe imports on those micro-enterprises. This study adopted a mixed-methods approach-using a combination of both qualitative and quantitative data collection methods. Face-to-face interviews with questionnaires, were done with a total sample of 62 owners of the micro-enterprises that use shweshwe as input, in the Western Cape (Cape Town) and Eastern Cape (i.e. Makhanda and East London), South Africa. Self-administered questionnaires were emailed to 20 Jackson’s Stores managers across the country. Lastly, face-to-face interviews were done with the key stakeholder-the representative of Cowie trading (the main shweshwe distributor) and Da Gama Textiles (the factory of shweshwe), during a field visit. The Qualitative data was analysed using thematic analysis, whereas the quantitative data was analysed using inferential and descriptive statistics. The results show, that the micro-enterprises that use shweshwe as input are a significant contributor in terms of employment creation and income generation in South Africa. They also reveal that there is a big number of micro-enterprises that use shweshwe as an input in SA. The findings showed an estimate of between 5077 and 6000 small businesses that are using shweshwe an input, which are associated with 10 900 to 12 900 jobs. It was also found out that there is a transformation in this industry, and that this sector is B-BEE compliant. There are also high levels of human capital in this industry. This is an important finding revealing that there is potential for future growth in this sector. Results also found that the majority micro-enterprise owners (80%) have no other source of income, meaning that they are highly reliant on their shweshwe sewing business income. Additionally, 85% of those business, shweshwe garments makes up half or more of their sewing business proceeds. This reveals that a decline in income caused by the import of ready-made clothes in “fake” shweshwe will have a negative impact on the micro-enterprises’ ability to contribute to economic growth and job creation in this industry. To show the impact of the import of ready-made clothes in “fake” shweshwe on the micro-enterprises’ ability to contribute to economic growth and job creation in this industry. In the questionnaires that were used to conduct face-to-face interviews with the micro-enterprises, respondents were asked to indicate whether they had other sources of income other than the income they generate from the shweshwe sewing business. They were further asked as follow up question to choose from a given list of possible options containing a range of percentages of their business income that comes from the work sewn with shweshwe. This question was asked in order to be able to see, if there were to be a decline in income caused by the import of ready-made clothes in “fake” shweshwe what impact it would have on the micro-enterprises that use shweshwe as an input. The theory of industrial organisation has adopted the view of that businesses operating in the formal sector are more efficient and productive than those in the informal sector (Lobato, 2010). The study found that the micro-enterprises that operate in the formal sector generate more turnover than the ones that operate in the informal sector. However, the theory was further tested by running OLS regression, the results showed that operating in the informal sector does not affect turnover when other variables are controlled for, however, that it does affect job creation. In closing, this thesis provides suggestions on how to support, and protect the micro-enterprises that use shweshwe as an input, in order to enhance this industry’s potential also to ensure its continuous contribution in terms of employment creation and income generation in South Africa.
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Labour market perceptions of students at a Technical and Vocational Education and Training (TVET) college in Grahamstown, South Africa

  • Authors: Khambule, Nelisa
  • Date: 2019
  • Subjects: Eastcape Midlands College (Makhanda, South Africa) -- Students -- Attitudes , College students -- South Africa -- Makhanda -- Attitudes , College graduates -- Employment -- South Africa , Labor market -- South Africa , Employability -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MSocSc
  • Identifier: http://hdl.handle.net/10962/96515 , vital:31289
  • Description: In the context of South Africa, the supply of intermediate to high-level skills is central to economic growth and development. The post-school education and training sector is a critical source of these skills. Technical and Vocational Education and Training (TVET) colleges are expected to provide the intermediate to high-level skills that are required in a fast-changing global and national economy. In addition to fulfilling the goal of meeting the skills needs of the country, TVET colleges are expected to expand access to education and training opportunities and create pathways that will ensure smooth transitions for learners from college to employment. Using the third-generation labour market segmentation approach to the study of labour markets, this study sought to investigate the various socio-political factors that influence TVET college students’ perceptions about employment opportunities in the labour market with a NCV qualification. Using a qualitative methodology, this research investigated whether TVET students at Eastcape Midlands College felt adequately prepared for the labour market with their prospective post-secondary school qualification. The findings varied, with some students being of the view that the theoretical component of their programme of study could be improved to better prepare them for the labour market, and others, being of the view that the practical component could be improved. At a general level, the findings showed that the students did not have perfect knowledge of the availability of employment opportunities for their prospective qualifications.
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Language-in-education policy and language practices in Botswana primary schools: a case study of 3 schools

  • Authors: Tselayakhumo, Dumelang
  • Date: 2019
  • Subjects: Translanguaging (Linguistics) , Multilingual education -- Botswana , Home and school -- Botswana , Language in contact -- Botswana , Language and education -- Case studies -- Botswana , Language policy -- Botswana
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/68271 , vital:29226
  • Description: This is a multiple case study of language practices in relation to the language-in-education policy of Botswana. The impetus for this study came after realising a decline in the academic achievement of learners as they move to higher levels of education. Taking into cognisance other factors like socio-economic background and marginalised communities, this study intended to investigate language practices at 3 primary schools at Standard 1, Standard 4 and Standard 7. Cases were selected from 3 various schools in different districts that present the language situation in Botswana. School A was in Kgalagadi district where the dominant spoken language is Shekgalagarhi, a minority language of Botswana. School B was in Southern district where the dominant spoken language is Setswana, the national language of Botswana and School C was in Gaborone city, the capital city of Botswana, where languages of Botswana come into contact and parents mainly use English to communicate with their children at home. Observation of language practices at these schools was the primary technique of data collection. The researcher also used questionnaires and focus group discussions for authentication. It was realised that whereas the language-in-education policy of Botswana is monoglossic, as it separates languages into separate functions, language practices in the three primary schools were transglossic, as they involved the use of different language varieties in the classroom. However, the researcher discovered that there was limited translanguaging that limited learner creativity and participation in class. The language practices revealed compliance and non-compliance of some schools to the national language-in-education policy. The researcher found language teaching to be one of the factors that limited content acquisition in content subject lessons. Realising the irrelevance of the policy to the linguistic needs of learners, this study proposes guidelines on the implementation of a multilingual micro policy that considers both the strong and the weak versions of translanguaging. This will open ways for translanguaging henceforth, active participation and enhanced performance for all Batswana. It also proposes the study of 3 languages: a minority language of Botswana, Setswana and English as compulsory subjects to embrace multilingualism and for the development of indigenous languages.
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Large scale spatio-temporal forcing of pelagic-coastal coupling: disentangling the effects of environmental change on intertidal invertebrate recruitment

  • Authors: Muñiz, Carlota Fernández
  • Date: 2019
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/75317 , vital:30400
  • Description: Marine systems are driven by the relationships among organisms and environmental conditions. Anthropogenic-induced changes during the past decades have started to alter climatic drivers which have the potential to alter the physical, chemical and biological environment. In coastal systems, biogeography is influenced by the temporal variability in the conditions of the water mass. In addition, many marine benthic organisms develop in the water mass and rely on the conditions that link the pelagic and benthic systems for population maintenance. Such pelagic-coastal coupling indicates that changes in the trophic system during development can be transferred to the adult populations through changes in propagule supply. Thus, changes in environmental conditions can influence benthic populations directly (e.g. through larval advection) or indirectly, through their influence on the phytoplankton community (e.g. through the development of HABs). The South African coastline shows clear alongshore patterns of faunal biomass and species richness. On the south coast, strong longitudinal patterns of recruitment of intertidal organisms exist, with areas of particularly high recruitment. HABs of unprecedented spatio-temporal magnitude have recently developed along the south coast, including the areas where benthic recruitment is most intense. The present thesis used these blooms to study changes in intertidal recruitment directly or indirectly associated with their occurrence. Using a combination of remote sensing data to study the environmental conditions of the water mass in the innermost part of the Agulhas Bank, and estimates of mussel and barnacle recruitment rates to integrate the effects of conditions in the water mass during larval development, this thesis aimed to: (1) understand the conditions that triggered the development of an HAB of the dinoflagellate Lingulodinium polyedrum during summer of 2014, (2) determine the direct or indirect effects of that bloom on recruitment of intertidal organisms, and understand the factors that affect recruitment along the coast, (3) determine if the environmental factors during bloom development produced any carryover effects on recruit growth and mortality, and (4) determine the factors that drive changes in community biomass and composition along the south coast, the long-term trends in those factors, and possible changes experienced in recent years. Water column stability during spring, before the development of the red tide, followed by alternating periods of upwelling and relaxation during summer and autumn, seemed to promote the development and persistence of L. polyedrum. Recruitment of mussels and barnacles was estimated during the reproductive season of mussels in 2014, coinciding with the red tide, and during the following year. Alongshore patterns in recruitment were found, with higher mussel recruitment in the absence of the red tide and the opposite pattern in barnacles. Alongshore patterns in SST and chlorophyll matching those of recruitment were also found, with higher SSTs and lower chlorophyll during the red tide than the following year. Growth and mortality rates in barnacles did not differ between years during the first five months after settlement. This suggests that the factors which produced differences in recruitment between years did not produce carryover effects detectable at the temporal scales studied. Further analysis of 15 years of satellite-derived environmental data showed significant cooling trends potentially driven by a long-term seasonal acceleration of the Agulhas Current in autumn around two upwelling centres on the south coast, coinciding temporally with the reproductive period of mussels and barnacles, and spatially with the areas of highest recruitment. In addition, the comparison of SST and chl-a conditions during the first and the second half of the period of study showed that seasonality of both variables has changed in large areas over the shelf, with increasing importance of shorter-term variability, which would in turn decrease environmental predictability. Thus, the conditions observed during the present study, particularly during 2015, when upwelling seemed to be more intense, may presage the potential effects of identified long-term cooling trends at the upwelling centres. Although the general trend shows cooling around those areas, conditions can vary greatly among years, favouring different taxa. Changes in the Agulhas Current System are affected by changes in distant areas in the Indian Ocean basin. Such tele-connection is unlikely to be unique to this system and indicates the importance of understanding trends in major large scale climatic drivers and their regional effects in order to make predictions about coastal systems.
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Large scale spatio-temporal forcing of pelagic-coastal coupling: disentangling the effects of environmental change on intertidal invertebrate recruitment

  • Authors: Muñiz, Carlota Fernández
  • Date: 2019
  • Subjects: Dinoflagellates -- South Africa , Coastal ecology -- South Africa , Climatic changes -- South Africa , Benthic ecology -- South Africa , Agulhas Current , Ocean temperature -- Agulhas Current , Ocean temperature -- Physiological effect
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/151541 , vital:39140
  • Description: Marine systems are driven by the relationships among organisms and environmental conditions. Anthropogenic-induced changes during the past decades have started to alter climatic drivers which have the potential to alter the physical, chemical and biological environment. In coastal systems, biogeography is influenced by the temporal variability in the conditions of the water mass. In addition, many marine benthic organisms develop in the water mass and rely on the conditions that link the pelagic and benthic systems for population maintenance. Such pelagic-coastal coupling indicates that changes in the trophic system during development can be transferred to the adult populations through changes in propagule supply. Thus, changes in environmental conditions can influence benthic populations directly (e.g. through larval advection) or indirectly, through their influence on the phytoplankton community (e.g. through the development of HABs). The South African coastline shows clear alongshore patterns of faunal biomass and species richness. On the south coast, strong longitudinal patterns of recruitment of intertidal organisms exist, with areas of particularly high recruitment. HABs of unprecedented spatio-temporal magnitude have recently developed along the south coast, including the areas where benthic recruitment is most intense. The present thesis used these blooms to study changes in intertidal recruitment directly or indirectly associated with their occurrence. Using a combination of remote sensing data to study the environmental conditions of the water mass in the innermost part of the Agulhas Bank, and estimates of mussel and barnacle recruitment rates to integrate the effects of conditions in the water mass during larval development, this thesis aimed to: (1) understand the conditions that triggered the development of an HAB of the dinoflagellate Lingulodinium polyedrum during summer of 2014, (2) determine the direct or indirect effects of that bloom on recruitment of intertidal organisms, and understand the factors that affect recruitment along the coast, (3) determine if the environmental factors during bloom development produced any carryover effects on recruit growth and mortality, and (4) determine the factors that drive changes in community biomass and composition along the south coast, the long-term trends in those factors, and possible changes experienced in recent years. Water column stability during spring, before the development of the red tide, followed by alternating periods of upwelling and relaxation during summer and autumn, seemed to promote the development and persistence of L. polyedrum. Recruitment of mussels and barnacles was estimated during the reproductive season of mussels in 2014, coinciding with the red tide, and during the following year. Alongshore patterns in recruitment were found, with higher mussel recruitment in the absence of the red tide and the opposite pattern in barnacles. Alongshore patterns in SST and chlorophyll matching those of recruitment were also found, with higher SSTs and lower chlorophyll during the red tide than the following year. Growth and mortality rates in barnacles did not differ between years during the first five months after settlement. This suggests that the factors which produced differences in recruitment between years did not produce carryover effects detectable at the temporal scales studied. Further analysis of 15 years of satellite-derived environmental data showed significant cooling trends potentially driven by a long-term seasonal acceleration of the Agulhas Current in autumn around two upwelling centres on the south coast, coinciding temporally with the reproductive period of mussels and barnacles, and spatially with the areas of highest recruitment. In addition, the comparison of SST and chl-a conditions during the first and the second half of the period of study showed that seasonality of both variables has changed in large areas over the shelf, with increasing importance of shorter-term variability, which would in turn decrease environmental predictability. Thus, the conditions observed during the present study, particularly during 2015, when upwelling seemed to be more intense, may presage the potential effects of identified long-term cooling trends at the upwelling centres. Although the general trend shows cooling around those areas, conditions can vary greatly among years, favouring different taxa. Changes in the Agulhas Current System are affected by changes in distant areas in the Indian Ocean basin. Such tele-connection is unlikely to be unique to this system and indicates the importance of understanding trends in major large scale climatic drivers and their regional effects in order to make predictions about coastal systems.
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Learning to learn: a critical realist exploration into the home established learning practices of a marginalised community in Port Elizabeth

  • Authors: Armstrong, Meredith
  • Date: 2019
  • Subjects: Minorities -- Education (Higher) -- South Africa , Readiness for school -- Social aspects -- South Africa , Inclusive education -- Social aspects -- South Africa , Marginality, Social -- South Africa , Critical realism
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/93778 , vital:30939
  • Description: This study was completed as part of a project exploring social inclusion and exclusion in South African higher education. In a globalised world, the achievement of a qualification from an institution of higher education is increasingly key to finding any sort of employment. This is particularly the case in South Africa where employment amongst black citizens is inordinately high. The aim of the research reported upon in this thesis was to better understand the construct of ‘epistemological access’ (Morrow, 1992), often used in relation to the needs of black working class students entering higher education, in relation to performance data (see for example, CHE, 2016) that repeatedly shows that black students fare less well than their white peers. Following what might be termed a ‘social’ approach to understanding access, this study begins long before most students have even heard of higher education and focuses on identifying the mechanisms that come into play at much earlier level of learning and literacy development. The study outlines the development of ‘ways of being’, or social practices, surrounding learning in a marginalised community in Port Elizabeth, in the Eastern Cape, South Africa. This was achieved by means of critical ethnography and it is therefore qualitatively based. The study shows how social structures enable or constrain a child’s school readiness and how they then go on to support or impede progress in school where the language and literacy needed for educational success are further developed. The study therefore aims to allow us to explain global data indicating that the single greatest indicator of a young person’s ability to access and succeed in higher education is the level of education of caregivers in their homes of origin. Examined from a critical perspective (i.e. with a concern for social justice), this study has made use of a framework using social, psychological and linguistic theory and more, particularly, the work of sociologist Margaret Archer (1995, 1996, 2003). The study makes particular use of Archer’s ‘morphogenetic framework’ which allows for an analysis of the way structure and culture impact on a child’s development over time. As I was concerned that my own social status might impact on the understandings I developed as a critical ethnographer, the study acknowledges my own experiences of learning and the way my own family sought to enhance them as enabling. In doing this, the study aims to better contribute to understandings of social justice in South Africa.
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Livestock water productivity: towards improving rural livelihoods from livestock in semi-arid rangelands

  • Authors: Gusha, Bukho
  • Date: 2019
  • Subjects: Livestock -- South Africa -- Eastern Cape , Livestock -- Effect of drought on -- South Africa -- Eastern Cape , Animals -- Food -- South Africa -- Eastern Cape , Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Livestock -- Water requirements -- South Africa -- Eastern Cape , Livestock productivity -- South Africa -- Eastern Cape , Stochastic analysis , Communal rangelands -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape , Animal owners -- South Africa -- Eastern Cape , Livestock improvement -- South Africa -- Eastern Cape
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/115171 , vital:34084
  • Description: Communal rangelands in South Africa mainly occur in the former homelands. The former homelands constitute 13% of the land surface area and support a quarter of the country's human population with a wide range of goods and services, among them, grazing for livestock, mostly reared on communal rangelands. These rangelands are degraded and cannot sustain maximum livestock production because of poor species composition and low standing biomass, however research has been conducted on livestock production at household level (where all livestock goods and services are valued). This provides an opportunity to conduct a study describing livestock water productivity in the north of the Eastern Cape, where livestock production is a primary source of livelihood for rural communities from which many households generate cash but where different practices and factors undermine high livestock production. Many studies have focused on understanding the water productivity of a natural rangeland system for commercially oriented crop-livestock systems, but the aim of this study is to contribute towards improving rural livelihoods from livestock in the sub-humid rangelands of the north Eastern Cape. Here, unimproved native grasslands are the major source of feed for livestock and people do not have herders to take livestock to the most productive parts of the rangelands. Households were surveyed using a questionnaire on livestock household contribution, socioeconomic characteristics of the household, livestock holdings and livestock production strategies. Rangeland productivity was measured in the field. Experimental animals for livestock grazing distribution were identified and fitted with Global Positioning Systems (GPS) collars to identify the seasonal grazing areas. These activities shed light on the biophysical attributes of the ecosystem and livestock production in a communal rangeland system. Because continuous grazing in the rangelands of the north Eastern Cape reduces the standing biomass, there is no obvious aboveground biomass to provide a visual perspective of production nor is it possible to determine production without excluding the livestock. Thus, four parallel lines of evidence were employed to measure rangeland productivity: line intercept, grazing exclosures, net photosynthesis from earth observation and disc pasture meter. Earth observation products were used to derive the amount of water used by the landscape to produce this forage (i.e. evapotranspiration or ET) and these measurements of net primary production and landscape water use were used in preparing a value of livestock water productivity (LWP) for this farming system. There has been the perception that residents of the study area lack knowledge of technical efficiencies in the large stock sector at household level. The study used stochastic frontier analysis to assess livestock production and followed with a household survey to collect information on socio-economic characteristics and information on livestock practices. The data from the household survey were used to estimate the technical efficiency of households using a stochastic frontier analysis. Productivity and inefficiency variables that increase livestock production or increase technical difficulties were identified. The focus on livestock has mostly been on the direct value of livestock to owners with a poor understanding of their value to non-livestock owners, where cultural activities, such as livestock slaughtering, were documented as the only source of protein for non-livestock owners. However, the value that is available to non-livestock owners has not been quantified. This study assessed livestockbased livelihoods of communal people to improve their livelihoods through a household survey looking at the contribution of livestock to both livestock and non-livestock owners. Earlier work on LWP has focused on systems where animals were on ‘fed, cut and carry’ and irrigated systems. However, there is a need to describe LWP in a natural grazing system and this study set out to achieve this for these communal rangelands through a household survey that determined the value of livestock goods and services given the amount of water used (ET). Lastly, livestock grazing distribution across the landscape was assessed, using GPS collars that recorded livestock behaviour every five minutes during the daylight. This approach was necessary because livestock grazing patterns in these communal rangelands is poorly controlled by people, and animals are largely free-ranging, grazing selectively, based on their own preferences, which leads to localised overgrazing. This part of the study was achieved through experimental livestock collaring and weighing (both sheep and goats) for the wet and dry seasons. The collared livestock were weighed on the day of putting on collars and the day of removing the collars. The results on livestock grazing distribution were analysed using the R package, T-LoCoH. The major finding of this study was that communal rangelands of the north Eastern Cape can improve rural livelihoods from livestock if proper interventions for both livestock and rangeland production and productivity can be implemented. One of these interventions is fencing as it was found that exclosures that were fenced during the study yielded high aboveground productivity comparable to that achieved in commercial rangelands, yielding 220 g DM m-2 yr-1. Surveys using the calibrated disc pasture meter showed the need for proper rotation and resting of the rangeland. Net photosynthesis of 880.7 g C m-2 yr-1 for unimproved grassland in good condition was comparable to commercial rangelands in the region. Using the line intercept, vegetation cover was found to be a good predictor of aboveground standing biomass; thus a positive relationship was revealed. Lastly, annual ET of 270 mm yr-1 was calculated using the Penman Monteith Palmer (PMP) equation, while 379 mm yr-1 was extracted from the MOD16 product, suggesting that PMP ET may not be accurate in these grassland systems due to the slow response of MODIS Leaf Area Index (LAI). The average household technical efficiency (TE) score was found to be 0.79 on the study sites, indicating the potential for households to improve outputs from livestock. A range of household categories were identified, based on gender and an index of wealth, and households with lower and higher TE were identified. This analysis revealed that productivity variables such as holding higher livestock numbers and providing additional feed achieved high livestock outputs, suggesting high livestock productivity. However, in terms of inefficiency variables, gender (female-headed households), dwelling type (an index of homestead wealth), kraaling livestock at night and herding livestock during the day were found to improve technical efficiency. It was revealed in this study that households keep livestock to derive different goods and services including offtake, manure, milk, wool and services such as traction. The non-livestock owning households were reported to also benefit from the abovementioned goods and services in the study site and that the value of their contribution could be quantified, thus contributing significantly to rural livelihoods. The study showed that LWP was comparable with other studies such as those conducted in Ethiopia. This study compared its results with the studies conducted outside South Africa as there were limited comparable South African studies available; however, this does not necessarily mean we can use the same model as the value of livestock outputs varies based on the preferred outputs. This study developed an LWP model for the natural rangeland system. The LWP values were measured in ZAR and later converted in USD and were divided into three different categories based on the wealth index, such as better-off, middle wealth and poor households. Lastly, this study showed that livestock (both cattle and sheep) spend a high proportion of their grazing day, during both the wet and dry seasons, in a small physical area, immediately around the homesteads. These are areas where the active green growth occurs throughout the year, suggesting the need for livestock herders to move livestock around the landscape for more effective landscape use. Herding has the potential to improve landscape use and conserve grazing resource and the ability of a household to attain best outputs from livestock. Positive daily weight gains were reported in collared livestock during the wet season. However, both sheep and cattle lost weight during the dry season. This study recommends interventions such as labour for herding, and other animal husbandry-related activities including milking, handling, and vaccinating animals. Market opportunities for communal rangeland livestock should be facilitated by informing livestock owners about livestock market specifications to improve their livelihoods. Lastly, proper grazing management planning, such as fencing, which enables rotational grazing, and herding which moves animals to the most productive parts of the rangeland, should be implemented so that rangelands can be rested for plant growth, vigour, and improved aboveground net primary productivity. Based on the recommendations made in this study, a research development approach is necessary which prioritises female empowerment in agriculture and poor farmers as female-headed households were reported by this study to be more technically efficient.
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Machine learning methods for calibrating radio interferometric data

  • Authors: Zitha, Simphiwe Nhlanhla
  • Date: 2019
  • Subjects: Calibration , Radio astronomy -- Data processing , Radio astronomy -- South Africa , Karoo Array Telescope (South Africa) , Radio telescopes -- South Africa , Common Astronomy Software Application (Computer software)
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/97096 , vital:31398
  • Description: The applications of machine learning have created an opportunity to deal with complex problems currently encountered in radio astronomy data processing. Calibration is one of the most important data processing steps required to produce high dynamic range images. This process involves the determination of calibration parameters, both instrumental and astronomical, to correct the collected data. Typically, astronomers use a package such as Common Astronomy Software Applications (CASA) to compute the gain solutions based on regular observations of a known calibrator source. In this work we present applications of machine learning to first generation calibration (1GC), using the KAT-7 telescope environmental and pointing sensor data recorded during observations. Applying machine learning to 1GC, as opposed to calculating the gain solutions in CASA, has shown evidence of reducing computation, as well as accurately predict the 1GC gain solutions representing the behaviour of the antenna during an observation. These methods are computationally less expensive, however they have not fully learned to generalise in predicting accurate 1GC solutions by looking at environmental and pointing sensors. We call this multi-output regression model ZCal, which is based on random forest, decision trees, extremely randomized trees and K-nearest neighbor algorithms. The prediction error obtained during the testing of our model on testing data is ≈ 0.01 < rmse < 0.09 for gain amplitude per antenna, and 0.2 rad < rmse <0.5 rad for gain phase. This shows that the instrumental parameters used to train our model more strongly correlate with gain amplitude effects than phase.
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Making meaning of reality television celebrities: the reception of South African Idol by young adults in Joza, Grahamstown

  • Authors: Magade, Mncedi Eddie
  • Date: 2019
  • Subjects: Talent shows (Television programs) -- South Africa , Television viewers -- South Africa , Television programs -- South Africa , Mass media -- South Africa , South African Idol (Television program) , Reality television shows
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/94217 , vital:31018
  • Description: Reality television or “factual entertainment” is a hybrid of old television formats and factual programming in order to create a “new” entertaining show designed to draw the attention of audiences and increase viewership ratings. South African Idol is one popular local example. Adapted from the British programme Pop Idol, the show promises upward mobility for the young star who wins the competition. This show has become a subject of conversation amongst young people in South Africa who aspire to the “success” and “celebrity” status that is produced by participating on the show. This paper uses a Cultural Studies framework in order to examine the relationship between texts and audiences as an aspect of the “circuit of culture,” with its interrelated moments of production, texts, consumption and lived experience. My research focuses on the text and audience “moments” of this circuit. Audience studies research suggests that we should situate television viewing and the meanings made of TV programs in the natural setting of the home, and that this setting should be taken seriously as a unit of analysis. This study therefore, seeks to understand the ways in which audiences make meaning of this television programme within the domestic context.
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Mapping and predicting potential distribution patterns of free-range livestock in the rural communal rangelands of Mgwalana, Eastern Cape, South Africa

  • Authors: Mkabile, Qawekazi
  • Date: 2019
  • Subjects: Range management -- South Africa , Grazing -- South Africa , Livestock -- South Africa , Livestock -- Monitoring -- South Africa , Livestock -- Remote sensing -- South Africa , Communal rangelands -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/96000 , vital:31223
  • Description: Communal rangelands provide habitat to many plants and animals. However, there is evidence that livestock cause range degradation. Range degradation occurs because livestock select grazing based on the availability of resources such as water and forage material, their use of the landscape is non-uniform, consequently causing resource deterioration. Range management is thus necessary because communities depend on range condition for livestock productivity. However, precise quantification of livestock distribution within communal rangelands is lacking. In developed countries, Global Positioning Systems (GPS) collars have been used to monitor wildlife and domestic livestock in pastures and seem to have worked efficiently. However, in a developing country like South Africa, GPS technology to monitor animal behaviour has been used only for wildlife on privately owned land. The high costs of monitoring livestock herds in large open areas such as communal rangelands have resulted in little or no monitoring of domestic livestock using GPS technology. This study links monitored livestock distribution to physical landscape variables in Mgwalana, and uses the modelled relationship to predict livestock distribution in quaternary catchments, T12A and T35A-E. The research addresses the questions (1) where do livestock spend time in the wet and dry seasons? And (2) how can areas of potential livestock distribution be identified in other catchments where actual distribution is unknown? Livestock were tracked during the wet and dry seasons using GPS collars. The resulting distribution data is combined with selected physical landscape variables to identify selectivity. The GPS location data and the physical landscape variables are used to predict potential livestock distribution where distribution is unknown in quaternary catchments (T12A and T35A-E). The ArcGIS Predictive Analysis Tool (PAT) was used to extract the selected landscape variable ranges based on the GPS location data and identify areas with the same conditions in the quaternary catchments were subsequently selected. The key findings are that livestock prefer accessible areas with gentle terrain near water sources, avoiding south-facing slopes which receive less solar radiation and tend to be cooler. Livestock are attracted to vegetation in riparian zones. Rural communal lands are dominated by poverty, and land-based livelihood strategies can potentially contribute to the well-being of the community. Therefore, understanding livestock distribution can contribute to a rangeland management strategy aimed at improving range condition which could increase livestock productivity and contribute to the livelihoods of local people.
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Memory of a dead river

  • Authors: Mayo, Thandokazi
  • Date: 2019
  • Subjects: Short stories, South African (English) , South African (English)
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/92364 , vital:30716
  • Description: My thesis is a collection of short stories that tap into cultural, literal references, both oral andvisual, and also draws on images I have seen and have struggled to get out of my head. The collection draws on Alissa Nutting’s distorted realism and Noy Holland’s evocative imagery to make even the most mundane things feel like something out of the ordinary. An unreal way of looking at real things. The stories are interrelated only insofar as they seek to normalise or neutralise the peculiarity of society’s seemingly outdated people who come from the rural areas. Their faces, their stories, their general mannerisms. To capture the tone of their emotions, their small plights, and to give an in-depth look into how where you are affects the very shape of your face.
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Mental health, where are we now?: a sociological analysis of the integration of mental health into primary healthcare in the Kingdom of Eswatini

  • Authors: Dlamini, Zenanile Zoe
  • Date: 2019
  • Subjects: Mental health services -- Eswatini , Psychiatric hospitals -- Eswatini , Primary health care -- Eswatini , Mentally ill -- Services for -- Eswatini , Mental health policy -- Eswatini
  • Language: English
  • Type: text , Thesis , Masters , MSocSci
  • Identifier: http://hdl.handle.net/10962/96269 , vital:31256
  • Description: This is a qualitative study exploring the integration of mental health into primary healthcare in the Kingdom of Eswatini. Primary healthcare forms the basis of any healthcare service provision. Primary Healthcare for mental health is an essential component of any well-functioning health system. Making mental healthcare available in primary healthcare allows for early detection and early treatment while it is still easier and cheaper. Purposive sampling was used to recruit nursesand a government official in the Hhohho region in the Kingdom of Eswatini.The study found that there are major challenges in the primary health care clinics, and this negatively affects the WHO (2001) proposal on mental health integration into primary health care. This finding is similar to other low-income countries’ challenges in mental health integration into primary health care. The impact of neo-liberal policies on healthcare in Eswatini is explored and it is clear these policies impact the ability of the Ministry of Health to provide health care. The study also drew on the symbolic interaction perspective to understand the meanings that nurses attach to mental illness and their experiences mental health care.
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Mesoscale alongshore and cross-shore transport and settlement of invertebrate larvae on the south east coast of South Africa

  • Authors: Dyantyi, Siphelele Buntu
  • Date: 2019
  • Subjects: Marine invertebrates -- Larvae -- Dispersal -- South Africa -- Eastern Cape , Benthic animals -- Larvae -- Dispersal -- South Africa -- Eastern Cape , Mexilhao mussel -- Larvae -- Dispersal -- South Africa -- Eastern Cape , Mytilus galloprovincialis -- Larvae -- Dispersal -- South Africa -- Eastern Cape , Oysters -- Larvae -- Dispersal -- South Africa -- Eastern Cape
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/97007 , vital:31386
  • Description: Pelagic larval stages of most marine benthic species are important in maintaining coastal populations of adults. Several physio-chemical factors such as currents, winds, larval behaviour and time have an influence on the dispersal and transport of larvae to the adult habitat but their role is however still poorly understood. The aim of this study was to investigate the alongshore and cross-shore transport and temporal delivery of invertebrate larvae at four sites (Kenton on Sea, Cannon Rocks, Schoenmakerskop and Cape St Francis) along the south east coast of Eastern Cape, South Africa. Larval distribution of several taxa was determined during two sampling periods, by collecting water samples at nearshore line transects (3 distances: 900m, 1500m and 2400m – perpendicular to the shore) and at three depths (surface, thermocline/middle, bottom), which ranged from 15m (inshore) to 50m (offshore). Physical properties (current speed and direction, dissolved oxygen, fluorescence, turbidity, temperature, salinity, pH, pressure, density and conductivity) were measured and coupled in order to further understand larval distribution. The larvae were analysed as both total abundance and separately as the abundances of a variety of taxa which were: Perna perna, Mytilus galloprovincialis, oysters, early and late nauplii and cyprids. Larval settlement and recruitment on the rocky shores were measured by monthly deployment and collection of 20 (10 each for barnacles and mussels) artificial collectors at each site, which were preserved in ethanol or frozen for further processing. Multiple Permutational Multivariate Analysis of Variance (PERMANOVA) analyses were used to test the effects of site, depth and distance from the shore for the nearshore larvae (taxa analysed separately). In addition, a distance based linear model (distLM) was performed to analyse the relationship between the total larval abundance and the above mentioned physical variables. Multiple two-way analyses of variance (ANOVA) were performed to test the effects of months and sites on the settlement and recruitment of the larvae (P. perna, M. galloprovincialis, other bivalves, cyprids and juvenile barnacles) arriving on the shore. For the nearshore larval distribution, results from the PERMANOVAs revealed that most taxa showed a significant site and depth interactions with the exception of ‘early nauplii’ taxon. Also nearly all taxa were found within the thermocline, besides ‘oyster’ and ‘cyprids’ which were located at thermocline or bottom. Larvae were also located at variable distances from the shore, with most occurring at the offshore stations. Furthermore, there was a geographical separation of larval abundance according to sites, with most larvae located at Cannon Rocks and Kenton on Sea and least at Schoenmakerskop and Cape St Francis. For the settlement and recruitment, most taxa showed a seasonal trend, with the highest abundance of settlers and recruits expectedly appearing during the summer months of the sampling period. Additionally there was a site effect for most taxa (P. perna, M. galloprovincialis, other bivalves and juvenile barnacles), where settlers and recruits were mostly found at Cannon Rocks. Significant differences in abundance of settlers and recruits amongst the four sites indicate spatial and temporal variability for the targeted 180km stretch of coast. Overall for this study, taxon and ontogenetic stage of larvae were important in the distribution and abundance of larvae. Throughout the time frame of nearshore and intertidal sampling, Cannon Rocks consistently resulted as a ‘hot spot’ for larval abundance, settlement and recruitment, while a broad west to east separation was also observed. These results hence highlight that within this stretch of c.180km coast, time, taxon, ontogeny and post-settlement factors influence early dynamics of benthic populations.
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Mineralogical, geochemical and lead isotopic analysis of the lead mineralization of the Skorpion Deposit, south western Namibia

  • Authors: Uazeua, Kakunauua
  • Date: 2019
  • Subjects: Zinc ores -- Namibia , Formations (Geology) -- Namibia , Mineralogy -- Namibia , Lead -- Metallurgy -- Namibia , Lead -- Isotopes -- Namibia
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/68391 , vital:29250
  • Description: The Skorpion none-sulphide Zinc Deposit is located in the para-autochtonous Port Nolloth Zone of the Gariep Belt, which overlays the Lower-Proterozoic Orange River Group basement rocks (Corrans et al., 1993). Situated in close proximity to the larger Rosh Pinah Zn-Pb deposit, the Skorpion Deposit contained a resource of 24.6 Mt at 10.6 % Zn and unquantified Cu and Pb prior to mining. To date, zinc has been the only metal exploited, with minor amounts of copper as a by-product. This study aims at understanding the mineralogical composition of the Skorpion lead mineralization and understanding the relationship between lead and the major metals such as zinc and copper in order to form a basis for further work that could determine the potential of processing lead as a by-product. As part of the study, work was also done on lead isotopes mainly with the aim of understanding the mineralization genesis and to determine the differences between the Skorpion and Rosh Pinah deposit which rationalize the inferior economic potential of the Skorpion lead mineralization. Results of the study have shown that majority of the lead mineralization is hosted by the felsic metavolcanics as galena and subordinately in the metasiliciclastics as pyromorphite, a lead manganese phosphate. In terms of the mineral textures, the lead minerals appear to be mainly secondary phases that have been remobilized and reprecipitated around pyrite, within pyrite cracks and intergrown with minerals such as chalcocite and greenockite. Lead has been mainly concentrated along fault zones. The elevated pyromorphite concentrations tend to occur within gossanous zones in close association with iron and manganese oxides. These textures represent supergene enrichment of a sulphide proto ore. However, contrary to copper and zinc mineralization, lead was not remobilized far from the proto ore merely as a function of its poor mobility in acidic fluids (Reddy et al., 1995). This substantiates the concentration of secondary lead in the felsic metavolcanics and to a much lesser extent, in the metasiliciclastics. Both secondary zinc and copper were reprecipitated in the metasiliciclastics, further away from the sulphide proto ore, hosted mainly by the felsic metavolcanics. The average lead isotope ratios of 206Pb/204Pb (17.26), 207Pb/204Pb (15.60) and 208Pb/204Pb (37.42) resemble results provided by Frimmel (2004) for both the Skorpion and Rosh Pinah deposits. For the Skorpion samples from Frimmel (2004) had the following average ratios: 206Pb/204Pb (17.29), 207Pb/204Pb (15.59) and 208Pb/204Pb (37.51). The Rosh Pinah samples had the following average ratios: 206Pb/204Pb (17.17), 207Pb/204Pb (15.61) and 208Pb/204Pb (37.45). These results indicate lead derivation from the lower 2.0 Ga Eburnean pre-Gariep basement in agreement with and Frimmel et al. (2004). The host felsic metavolcanics might have been derived from melting of the basement rocks during the formation of the Adamastor Ocean. In comparison to the Rosh Pinah deposit lead isotope signatures, the Skorpion lead isotopes overlap with the Rosh Pinah deposit isotopes, but have a much narrower range. This is an indication of a much shorter lived and potentially faster mineralization event contrary to the SEDEX type Rosh Pinah deposit. The smaller tonnage of the Skorpion deposit, its inferior lead concentrations and the elevated radiogenic lead isotopes point toward a VMS deposit which was formed in a small graben fed by shallow conduits during a short lived mineralization event. Sedimentary rocks covered the forming deposit at a fast rate and impaired the deposit advancement. The interaction between the upper crustal rocks and the mineralizing fluids is what may have resulted in the elevated radiogenic lead signature. In contrast to this, SEDEX deposits such as the Rosh Pinah Deposit, are generally fed by deep seated conduits that allow more longer lived leaching of metals from the underlying basement rocks and generally allow minor influence from upper crustal rocks.
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