An investigation of servant leadership within Rhodes University sports clubs
- Authors: Stiebel, Jessica Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:872 , http://hdl.handle.net/10962/d1021317
- Description: This research investigates the level of servant leadership within Rhodes University sport clubs. The goals of this research are to assess the perception the club members have of their chairperson and to key identify areas of development. The sport clubs at Rhodes University are partially run by chairpersons who are voted into the position by his or her peers of a sports club. The chairpersons work alongside Rhodes University employees who are a part of the Sports Administration team to oversee the running, scheduling and finances of the club. The sports clubs are representative of Rhodes University and it is the chairperson’s responsibility to ensure the club is lead and run effectively. Robert Greenleaf coined the term servant leader in the 1970s (Greenleaf, 1997). The servant leader is a leader who is driven by his or her followers, as leadership involves a leader serving his or her followers first and foremost (Greenleaf, 1977). The leader takes on a role that is supportive and contributes to their personal as well as their professional achievements (Smith, Montagno and Kuzmenko, 2004). A questionnaire consisting of 27 questions was drafted, of which were four demographic questions. A 5-point Likert Scale was used in order for the participants to respond to the questions. The questionnaire was drawn from a number of questionnaires available in literature on leadership and adapted to suit Rhodes University sports clubs. The questionnaire was distributed personally by the researcher, as well as through an online questionnaire. There were a total of 153 candidates who participated in the study. Descriptive statistics were used to analyse the data. The majority of the respondents had the perceptions that their chairperson displayed characteristics of a servant leader. Majority of the participants were in agreement of the questions asked in the questionnaire, which focused on many servant leadership qualities. The results will be handed over to the Head of Sports Administration in order for them to get an idea of their leaders’ characteristics and areas where they can improve upon.
- Full Text:
- Date Issued: 2016
- Authors: Stiebel, Jessica Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:872 , http://hdl.handle.net/10962/d1021317
- Description: This research investigates the level of servant leadership within Rhodes University sport clubs. The goals of this research are to assess the perception the club members have of their chairperson and to key identify areas of development. The sport clubs at Rhodes University are partially run by chairpersons who are voted into the position by his or her peers of a sports club. The chairpersons work alongside Rhodes University employees who are a part of the Sports Administration team to oversee the running, scheduling and finances of the club. The sports clubs are representative of Rhodes University and it is the chairperson’s responsibility to ensure the club is lead and run effectively. Robert Greenleaf coined the term servant leader in the 1970s (Greenleaf, 1997). The servant leader is a leader who is driven by his or her followers, as leadership involves a leader serving his or her followers first and foremost (Greenleaf, 1977). The leader takes on a role that is supportive and contributes to their personal as well as their professional achievements (Smith, Montagno and Kuzmenko, 2004). A questionnaire consisting of 27 questions was drafted, of which were four demographic questions. A 5-point Likert Scale was used in order for the participants to respond to the questions. The questionnaire was drawn from a number of questionnaires available in literature on leadership and adapted to suit Rhodes University sports clubs. The questionnaire was distributed personally by the researcher, as well as through an online questionnaire. There were a total of 153 candidates who participated in the study. Descriptive statistics were used to analyse the data. The majority of the respondents had the perceptions that their chairperson displayed characteristics of a servant leader. Majority of the participants were in agreement of the questions asked in the questionnaire, which focused on many servant leadership qualities. The results will be handed over to the Head of Sports Administration in order for them to get an idea of their leaders’ characteristics and areas where they can improve upon.
- Full Text:
- Date Issued: 2016
An investigation of the aquatic macroinvertebrate fauna of the southern Great Escarpment (South Africa): insights from ecological and genetic studies
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
An investigation of the barriers and drivers to CDM renewable energy investment at the Metro, Kouga and Jeffreys Bay windfarms
- Authors: Staples, Daryl Nolan
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:871 , http://hdl.handle.net/10962/d1021316
- Description: This research is presented in three sections. Section 1 presents the research report in an academic journal article format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed during the research. Climate change is the most urgent challenge facing planet earth today. The Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) clearly states, “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems” (IPCC, 2014:2). The Renewable Energy Policy Network for the 21st Century (REN21) published the 10th annual edition of the Renewables 2015 Global Status Report, which illustrates the importance of a zero emissions energy sector (REN21, 2015). Despite the world’s average annual 1,5% increase in energy consumption in recent years, and average 3% growth in Gross Domestic Product, carbon dioxide (CO2) emissions in 2014 were unchanged from 2013 levels (REN21, 2015). The report findings state, “For the first time in four decades, the world economy grew without a parallel rise in CO2 emissions” (REN21, 2015:17). Renewable energy and improved energy efficiency is key to limiting global warming and avoiding dangerous impacts from climate change (REN21, 2015). With a view to the successful outcome of the 21st Conference of the Parties (COP21) in December 2015, renewable energy could contribute significantly in mitigating climate change and supporting the Sustainable Development Goals (SDGs), specifically SDG 7, on Sustainable Energy for All (SAIREC, 2015). South Africa has been rated the 15th most attractive destination for investment in the renewable energy sector and could become a renewable energy leader in the African continent, according to the Renewable Energy Country Attractiveness Index of EY (Ernest and Young) (EY, 2015). And more...
- Full Text:
- Date Issued: 2016
- Authors: Staples, Daryl Nolan
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:871 , http://hdl.handle.net/10962/d1021316
- Description: This research is presented in three sections. Section 1 presents the research report in an academic journal article format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed during the research. Climate change is the most urgent challenge facing planet earth today. The Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) clearly states, “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems” (IPCC, 2014:2). The Renewable Energy Policy Network for the 21st Century (REN21) published the 10th annual edition of the Renewables 2015 Global Status Report, which illustrates the importance of a zero emissions energy sector (REN21, 2015). Despite the world’s average annual 1,5% increase in energy consumption in recent years, and average 3% growth in Gross Domestic Product, carbon dioxide (CO2) emissions in 2014 were unchanged from 2013 levels (REN21, 2015). The report findings state, “For the first time in four decades, the world economy grew without a parallel rise in CO2 emissions” (REN21, 2015:17). Renewable energy and improved energy efficiency is key to limiting global warming and avoiding dangerous impacts from climate change (REN21, 2015). With a view to the successful outcome of the 21st Conference of the Parties (COP21) in December 2015, renewable energy could contribute significantly in mitigating climate change and supporting the Sustainable Development Goals (SDGs), specifically SDG 7, on Sustainable Energy for All (SAIREC, 2015). South Africa has been rated the 15th most attractive destination for investment in the renewable energy sector and could become a renewable energy leader in the African continent, according to the Renewable Energy Country Attractiveness Index of EY (Ernest and Young) (EY, 2015). And more...
- Full Text:
- Date Issued: 2016
An investigation of the history and works of the Keiskamma Art Project
- Authors: Osner, Heather
- Date: 2016
- Subjects: Community arts projects -- South Africa -- Eastern Cape , Artists and community -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13038 , vital:27146
- Description: This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa. This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty-stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Osner, Heather
- Date: 2016
- Subjects: Community arts projects -- South Africa -- Eastern Cape , Artists and community -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13038 , vital:27146
- Description: This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa. This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty-stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.
- Full Text:
- Date Issued: 2016
An investigation of the morphological and electrochemical properties of spinel cathode oxide materials used in li-ion batteries
- Authors: Snyders, Charmelle
- Date: 2016
- Subjects: Lithium ion batteries Cathodes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12929 , vital:27135
- Description: Li-ion batteries have become the more dominant battery type used in portable electronic devices such as cell phones, computers and more recently their application in full electric vehicles (EV). Li-ion batteries have many advantages over the traditional rechargeable systems (Pb-acid and Ni-MH) such as their higher energy density, low self-discharge, long capacity cycle life and relatively maintenance free. Due to their commercial advantages, a lot of research is done in developing new novel Li-ion electrode materials, improving existing ones and to reduce manufacturing costs in order to make them more cost effective in their applications. This study looked at the cathode material chemistry that has a typical spinel manganese oxide (LiMn2O4) type structure. For comparison the study also considered the influence of doping the phase with various metals such as Al, Mg, Co and Ni that were made as precursors using various carboxylic acids (Citric, Ascorbic, Succinic and Poly-acrylic acid) from a sol-gel process. Traditional batch methods of synthesizing the electrode material is costly and do not necessarily provide optimized electrochemical performance. Alternative continuous less energy intensive methods would help reduce the costs of the preparation of the electrode materials. This study investigated the influence of two synthesis techniques on the materials physical and electrochemical characteristics. These synthesis methods included the use of a typical batch sol-gel method and the continuous spray-drying technique. The spinel materials were prepared and characterized by Powder X-Ray Diffraction (PXRD) to confirm the formation of various phases during the synthesis process. In addition, in-situ PXRD techniques were used to track the phase changes that occurred in the typical batch synthesis process from a sol-gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis (TGA), whereby the materials decomposition mechanisms were observed as the precursor was gradually heated to the final oxide. These synthesized materials prepared under various conditions were then used to build suitable Li-ion coin type of cells, whereby their electrochemical properties were tested by simple capacity tests and electrochemical impedance spectroscopy (EIS). EIS measurements were done on the built cells with the various materials at various charge voltages. TG analysis showed that the materials underwent multiple decomposition steps upon heating for the doped lithium manganese oxides, whereas the undoped oxide showed only a single decomposition step. The results showed that all the materials achieved their weight loss below 400 °C, and that the final spinel oxide had already formed. The in-situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and then finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4, and LiCo1.09Mn0.91O4). For other materials, the precursor would start as an amorphous phase, and then upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4 and LiNi0.5Mn1.5O4). The in-situ study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C. Hence the results implied that a type of sintering of the particles would occur at temperatures above 600 °C, thereby increasing the respective crystallite size. The study showed that the cathode active materials made by the sol-gel spray-drying method would give a material that had a significantly larger surface area and a smaller crystallite size when compared to the materials made by the batch process. The electrochemical analysis showed that there was only a slight increase in the discharge capacities of the cells made with the spray-drying technique when compared to the cells made with the materials from the batch sol-gel technique. Whereas, the EIS study showed that there were distinct differences in the charging behavior of the cells made with the various materials using different synthesis techniques. The EIS results showed that there was a general decrease in the cells charge transfer resistance (Rct) as the charge potential increased regardless of the synthesis method used for the various materials. The results also showed that the lithium-ion diffusion coefficient (DLi) obtained from EIS measurements were in most of the samples higher for the cathode materials that had a larger surface area. This implied that the Li-ion could diffuse at a faster rate through the bulk material. The study concluded that by optimizing the synthesis process in terms of the careful control of the thermal parameters, the Li-ion batteries‟ cathode active material of the manganese spinel type could be optimized and be manufactured by using a continuous flow micro spray process.
- Full Text:
- Date Issued: 2016
- Authors: Snyders, Charmelle
- Date: 2016
- Subjects: Lithium ion batteries Cathodes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12929 , vital:27135
- Description: Li-ion batteries have become the more dominant battery type used in portable electronic devices such as cell phones, computers and more recently their application in full electric vehicles (EV). Li-ion batteries have many advantages over the traditional rechargeable systems (Pb-acid and Ni-MH) such as their higher energy density, low self-discharge, long capacity cycle life and relatively maintenance free. Due to their commercial advantages, a lot of research is done in developing new novel Li-ion electrode materials, improving existing ones and to reduce manufacturing costs in order to make them more cost effective in their applications. This study looked at the cathode material chemistry that has a typical spinel manganese oxide (LiMn2O4) type structure. For comparison the study also considered the influence of doping the phase with various metals such as Al, Mg, Co and Ni that were made as precursors using various carboxylic acids (Citric, Ascorbic, Succinic and Poly-acrylic acid) from a sol-gel process. Traditional batch methods of synthesizing the electrode material is costly and do not necessarily provide optimized electrochemical performance. Alternative continuous less energy intensive methods would help reduce the costs of the preparation of the electrode materials. This study investigated the influence of two synthesis techniques on the materials physical and electrochemical characteristics. These synthesis methods included the use of a typical batch sol-gel method and the continuous spray-drying technique. The spinel materials were prepared and characterized by Powder X-Ray Diffraction (PXRD) to confirm the formation of various phases during the synthesis process. In addition, in-situ PXRD techniques were used to track the phase changes that occurred in the typical batch synthesis process from a sol-gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis (TGA), whereby the materials decomposition mechanisms were observed as the precursor was gradually heated to the final oxide. These synthesized materials prepared under various conditions were then used to build suitable Li-ion coin type of cells, whereby their electrochemical properties were tested by simple capacity tests and electrochemical impedance spectroscopy (EIS). EIS measurements were done on the built cells with the various materials at various charge voltages. TG analysis showed that the materials underwent multiple decomposition steps upon heating for the doped lithium manganese oxides, whereas the undoped oxide showed only a single decomposition step. The results showed that all the materials achieved their weight loss below 400 °C, and that the final spinel oxide had already formed. The in-situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and then finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4, and LiCo1.09Mn0.91O4). For other materials, the precursor would start as an amorphous phase, and then upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4 and LiNi0.5Mn1.5O4). The in-situ study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C. Hence the results implied that a type of sintering of the particles would occur at temperatures above 600 °C, thereby increasing the respective crystallite size. The study showed that the cathode active materials made by the sol-gel spray-drying method would give a material that had a significantly larger surface area and a smaller crystallite size when compared to the materials made by the batch process. The electrochemical analysis showed that there was only a slight increase in the discharge capacities of the cells made with the spray-drying technique when compared to the cells made with the materials from the batch sol-gel technique. Whereas, the EIS study showed that there were distinct differences in the charging behavior of the cells made with the various materials using different synthesis techniques. The EIS results showed that there was a general decrease in the cells charge transfer resistance (Rct) as the charge potential increased regardless of the synthesis method used for the various materials. The results also showed that the lithium-ion diffusion coefficient (DLi) obtained from EIS measurements were in most of the samples higher for the cathode materials that had a larger surface area. This implied that the Li-ion could diffuse at a faster rate through the bulk material. The study concluded that by optimizing the synthesis process in terms of the careful control of the thermal parameters, the Li-ion batteries‟ cathode active material of the manganese spinel type could be optimized and be manufactured by using a continuous flow micro spray process.
- Full Text:
- Date Issued: 2016
An investigation of the practices employed by an environmental community-based organization to successfully sustain its school based and community based projects (A case study)
- Authors: Hlophe, Nomalanga Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2073 , http://hdl.handle.net/10962/d1021252
- Description: Community-based organizations (CBOs) play a crucial role in sustainable development and hence it is important that they are promoted, guided and supported by state agencies and the private sector. The South African government encourages communities to establish co-operatives as a tool or strategy to address local social issues and risks and act accordingly. The purpose of this case study was to determine what aspects of the establishment and operation of a successful community-based environmental organization are producing sustained school and community projects. The study set out to investigate and audit the activities of a successful environmental CBO so as to determine how it has successfully sustained its school and community environmental projects. The reason for this investigation was to inform other CBOs and the state environmental agencies that support them on how to sustain their environmental activities in community and school contexts. The investigation was designed as an interpretive case study, which used document analysis, semi-structured interviews and observations to gather data. The gathered data was analyzed through inductive analysis to interpret and audit reported activities. Analytical memos were used to represent key themes in relation to the successful operations of the organization. Through auditing and reporting the activities in the analytical memos, analytical statements were developed. Those statements guided the discussion and informed the study‟s findings and recommendations. After investigating this CBO, it was concluded that, their success is a result of the establishment of a networking forum with different stakeholders and parties, community involvement in different projects, partnerships with local schools to develop and expand their curriculum practice, CBO networking locally and internationally and finally, their participation in annual and continuous environmental competitions/projects/programs. The insights gained and lessons learned will be used to advice and support community based co-operatives in environmental learning activities in school and community contexts as part of my ongoing work.
- Full Text:
- Date Issued: 2016
- Authors: Hlophe, Nomalanga Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2073 , http://hdl.handle.net/10962/d1021252
- Description: Community-based organizations (CBOs) play a crucial role in sustainable development and hence it is important that they are promoted, guided and supported by state agencies and the private sector. The South African government encourages communities to establish co-operatives as a tool or strategy to address local social issues and risks and act accordingly. The purpose of this case study was to determine what aspects of the establishment and operation of a successful community-based environmental organization are producing sustained school and community projects. The study set out to investigate and audit the activities of a successful environmental CBO so as to determine how it has successfully sustained its school and community environmental projects. The reason for this investigation was to inform other CBOs and the state environmental agencies that support them on how to sustain their environmental activities in community and school contexts. The investigation was designed as an interpretive case study, which used document analysis, semi-structured interviews and observations to gather data. The gathered data was analyzed through inductive analysis to interpret and audit reported activities. Analytical memos were used to represent key themes in relation to the successful operations of the organization. Through auditing and reporting the activities in the analytical memos, analytical statements were developed. Those statements guided the discussion and informed the study‟s findings and recommendations. After investigating this CBO, it was concluded that, their success is a result of the establishment of a networking forum with different stakeholders and parties, community involvement in different projects, partnerships with local schools to develop and expand their curriculum practice, CBO networking locally and internationally and finally, their participation in annual and continuous environmental competitions/projects/programs. The insights gained and lessons learned will be used to advice and support community based co-operatives in environmental learning activities in school and community contexts as part of my ongoing work.
- Full Text:
- Date Issued: 2016
An investigation of the teaching strategies employed by a selection of educators at an FET college to support at risk L2 tourism students
- Authors: Tsotso, Nosipho
- Date: 2016
- Subjects: Critical thinking -- Study and teaching , Vocational education -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/7225 , vital:21310
- Description: The South African education system is based on learner centred principles and encourages the development of critical thinking. This approach is reflected in the South African Qualifications Framework, which identifies critical thinking as a primary outcome of education. In the vocational Tourism programme, there is a link between the subject learning outcomes and critical crossfield outcomes. The role of the vocational college educator is central in facilitating the development of critical thinking skills of all learners. The purpose of this study was to investigate how the selected Tourism educators develop critical thinking skills of risk L2 students. I conducted the study in a selected FET College using a qualitative case study in order to gain deeper understanding of how the educators implement curriculum policy in their classrooms. This study used four data collection instruments to gain an in-depth understanding of the research topic. The findings of the study reveal that educators understand the value of teaching critical thinking. However, there is a gap between educators’ conceptual understanding of critical thinking and their instructional practice to develop critical thinking skills during classroom instruction. The findings also reveal that there are factors that hinder the development of at risk students’ critical thinking skills such as; limited English language proficiency, poor behaviour, and subject guidelines which do not provide educators with guidance on teaching critical thinking skills. The study recommends in-service training sessions that will support educators on how to teach critical thinking skills explicitly. This study also recommends the development of practical guidelines to enhance educators’ critical thinking teaching strategies. The findings of this research will assist me in improving the support that I provide to Tourism educators.
- Full Text:
- Date Issued: 2016
- Authors: Tsotso, Nosipho
- Date: 2016
- Subjects: Critical thinking -- Study and teaching , Vocational education -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/7225 , vital:21310
- Description: The South African education system is based on learner centred principles and encourages the development of critical thinking. This approach is reflected in the South African Qualifications Framework, which identifies critical thinking as a primary outcome of education. In the vocational Tourism programme, there is a link between the subject learning outcomes and critical crossfield outcomes. The role of the vocational college educator is central in facilitating the development of critical thinking skills of all learners. The purpose of this study was to investigate how the selected Tourism educators develop critical thinking skills of risk L2 students. I conducted the study in a selected FET College using a qualitative case study in order to gain deeper understanding of how the educators implement curriculum policy in their classrooms. This study used four data collection instruments to gain an in-depth understanding of the research topic. The findings of the study reveal that educators understand the value of teaching critical thinking. However, there is a gap between educators’ conceptual understanding of critical thinking and their instructional practice to develop critical thinking skills during classroom instruction. The findings also reveal that there are factors that hinder the development of at risk students’ critical thinking skills such as; limited English language proficiency, poor behaviour, and subject guidelines which do not provide educators with guidance on teaching critical thinking skills. The study recommends in-service training sessions that will support educators on how to teach critical thinking skills explicitly. This study also recommends the development of practical guidelines to enhance educators’ critical thinking teaching strategies. The findings of this research will assist me in improving the support that I provide to Tourism educators.
- Full Text:
- Date Issued: 2016
An investigation on the effect of Russian wheat aphid (Diuraphis noxia Kurdjumov) population growth and feeding damage on selected barley (Hordeum vulgare L.) cultivars under ambient and elevated CO2
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
An overview of language policy implementation in the City of Tswane Metropolitan Municipality with a focus on translation as an activity of language policy implementation
- Seshoka, Keaobaka Omphile Precious
- Authors: Seshoka, Keaobaka Omphile Precious
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/932 , vital:20004
- Description: The South African Municipality Systems Act (2000) states that language should not act as a barrier of access for citizens with no or limited proficiency in English to municipal services, or in ensuring the right of citizens to participate in, and contribute to the social, cultural, intellectual, economic and political life of South African society. In that regard, it recommends that South African municipalities develop a culture of public participation by providing services in a language preferred and used by citizens within their municipality through translation, amongst other things. This study examines how the translation services, as articulated in the language policy and plan of the City of Tshwane Metropolitan Municipality, is used as a language implementation strategy and in facilitating public participation. It further assesses the quality of the translated information accessed by the different residents of the City of Tshwane Metropolitan Municipality against theories of translation appraisal. The main focus area of this research is on extent of the use of translation as an activity of corpus planning, to facilitate language policy implementation in the City of Tshwane Municipality to enable better public participation. It is hoped that the study will be able to give policy makers and those tasked with implementation, especially at government municipalities‘ strategies to assess and determine the state of translation services to improve functionality, quality and the extent to which translation activities contribute to corpus planning.
- Full Text:
- Date Issued: 2016
- Authors: Seshoka, Keaobaka Omphile Precious
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/932 , vital:20004
- Description: The South African Municipality Systems Act (2000) states that language should not act as a barrier of access for citizens with no or limited proficiency in English to municipal services, or in ensuring the right of citizens to participate in, and contribute to the social, cultural, intellectual, economic and political life of South African society. In that regard, it recommends that South African municipalities develop a culture of public participation by providing services in a language preferred and used by citizens within their municipality through translation, amongst other things. This study examines how the translation services, as articulated in the language policy and plan of the City of Tshwane Metropolitan Municipality, is used as a language implementation strategy and in facilitating public participation. It further assesses the quality of the translated information accessed by the different residents of the City of Tshwane Metropolitan Municipality against theories of translation appraisal. The main focus area of this research is on extent of the use of translation as an activity of corpus planning, to facilitate language policy implementation in the City of Tshwane Municipality to enable better public participation. It is hoped that the study will be able to give policy makers and those tasked with implementation, especially at government municipalities‘ strategies to assess and determine the state of translation services to improve functionality, quality and the extent to which translation activities contribute to corpus planning.
- Full Text:
- Date Issued: 2016
An overview of linux container based network emulation
- Peach, Schalk, Irwin, Barry V W, van Heerden, Renier
- Authors: Peach, Schalk , Irwin, Barry V W , van Heerden, Renier
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430095 , vital:72665 , https://www.proceedings.com/30838.html
- Description: The objective of this paper is to assess the current state of Container-Based Emulator implementations on the Linux platform. Through a nar-rative overview, a selection of open source Container-Based emulators are analysed to collect information regarding the technologies used to construct them to assess the current state of this emerging technology. Container-Based Emulators allows the creation of small emulated net-works on commodity hardware through the use of kernel level virtualiza-tion techniques, also referred to as containerisation. Container-Based Emulators act as a management tool to control containers and the ap-plications that execute within them. The ability of Container Based Emu-lators to create repeatable and controllable test networks makes it ideal for use as training and experimentation tools in the information security and network management fields. Due to the ease of use and low hard-ware requirements, the tools present a low cost alternative to other forms of network experimentation platforms. Through a review of cur-rent literature and source code, the current state of Container-Based Emulators is assessed.
- Full Text:
- Date Issued: 2016
- Authors: Peach, Schalk , Irwin, Barry V W , van Heerden, Renier
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430095 , vital:72665 , https://www.proceedings.com/30838.html
- Description: The objective of this paper is to assess the current state of Container-Based Emulator implementations on the Linux platform. Through a nar-rative overview, a selection of open source Container-Based emulators are analysed to collect information regarding the technologies used to construct them to assess the current state of this emerging technology. Container-Based Emulators allows the creation of small emulated net-works on commodity hardware through the use of kernel level virtualiza-tion techniques, also referred to as containerisation. Container-Based Emulators act as a management tool to control containers and the ap-plications that execute within them. The ability of Container Based Emu-lators to create repeatable and controllable test networks makes it ideal for use as training and experimentation tools in the information security and network management fields. Due to the ease of use and low hard-ware requirements, the tools present a low cost alternative to other forms of network experimentation platforms. Through a review of cur-rent literature and source code, the current state of Container-Based Emulators is assessed.
- Full Text:
- Date Issued: 2016
An unsung dialogue: music, society and the history of The Flames
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
Analysis of non-peptidic compounds as potential malarial inhibitors against plasmodial cysteine proteases via integrated virtual screening workflow
- Musyoka, Thommas M, Kanzi, Aquillah M, Lobb, Kevin A, Tastan Bishop, Özlem
- Authors: Musyoka, Thommas M , Kanzi, Aquillah M , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123074 , vital:35403 , https://doi.10.1080/07391102.2015.1108231
- Description: Malaria is an infectious disease caused by a diverse group of erythrocytic protozoan parasites of the genus Plasmodium. It remains an exigent public health problem in the tropical areas of Africa, South America and parts of Asia and continues to take its toll in morbidity and mortality with half of the world’s population under a permanent risk of infection leading to more than half a million deaths annually (WHO, 2013). Five Plasmodium species, namely P. falciparum (Pf ), P. vivax (Pv), P. ovale (Po), P. malariae (Pm) and P. knowlesi (Pk), are known to infect humans with Pf responsible for more than 90% of the malarial fatalities reported in sub-Saharan Africa. The predominance of Pf is attributed to its adaptability (Ashley, McGready, Proux, & Nosten, 2006; Prugnolle et al., 2011). Although the high occurrence of the Duffy negative trait among African populations lowers the threat posed by Pv, it is the most frequent and widely causative agent of benign tertian malaria in other parts of the world (Mendis, Sina, Marchesini, & Carter, 2001). In addition to the listed human malarial parasite forms, several other Plasmodium species, which infect non-human laboratory models, have been identified and are of significant importance in understanding the parasite biology, the host–parasite interactions and in the drug development process (Langhorne et al., 2011).
- Full Text:
- Date Issued: 2016
- Authors: Musyoka, Thommas M , Kanzi, Aquillah M , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123074 , vital:35403 , https://doi.10.1080/07391102.2015.1108231
- Description: Malaria is an infectious disease caused by a diverse group of erythrocytic protozoan parasites of the genus Plasmodium. It remains an exigent public health problem in the tropical areas of Africa, South America and parts of Asia and continues to take its toll in morbidity and mortality with half of the world’s population under a permanent risk of infection leading to more than half a million deaths annually (WHO, 2013). Five Plasmodium species, namely P. falciparum (Pf ), P. vivax (Pv), P. ovale (Po), P. malariae (Pm) and P. knowlesi (Pk), are known to infect humans with Pf responsible for more than 90% of the malarial fatalities reported in sub-Saharan Africa. The predominance of Pf is attributed to its adaptability (Ashley, McGready, Proux, & Nosten, 2006; Prugnolle et al., 2011). Although the high occurrence of the Duffy negative trait among African populations lowers the threat posed by Pv, it is the most frequent and widely causative agent of benign tertian malaria in other parts of the world (Mendis, Sina, Marchesini, & Carter, 2001). In addition to the listed human malarial parasite forms, several other Plasmodium species, which infect non-human laboratory models, have been identified and are of significant importance in understanding the parasite biology, the host–parasite interactions and in the drug development process (Langhorne et al., 2011).
- Full Text:
- Date Issued: 2016
Anti-diabetic and phytochemical analysis of sutherlandia frutescens extracts
- Authors: Adefuye, Ogheneochuko Janet
- Date: 2016
- Subjects: Medicinal plants -- Africa , Traditional medicine -- Africa , Herbs -- Therapeutic use -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/3549 , vital:20441
- Description: In Africa, the importance of medicinal plants in folklore medicine and their contribution to primary healthcare is well recognized. Across the continent, local herbal mixtures still provide the only therapeutic option for about 80% of the population. The vast floral diversity and the intrinsic ethnobotanical knowledge has been the backbone of localized traditional herbal medical practices. In Africa, an estimated 5400 of the 60000 described plant taxa possess over 16300 therapeutic uses. Similarly, with a therapeutic flora comprising of approximately 650 species, herbal medical practitioners in South Africa, make use of a plethora of plants to treat different human diseases and infections. Over the years, studies have identified numerous plant species with potential against chronic metabolic diseases including type 2 diabetes mellitus (T2DM). Globally, the incidence and prevalence of T2DM have reached epidemic proportions affecting people of all ages, nationalities and ethnicity. Considered the fourth leading cause of deaths by disease, T2DM is a global health crisis with an estimated diagnosis and mortality frequency of 1 every 5 seconds and 1 every 7 seconds respectively. Though the exact pathophysiology of T2DM is not entirely understood, initial peripheral insulin resistance in adipose tissue, liver, and skeletal muscle with subsequent pancreatic β-cell dysfunction resulting from an attempt to compensate for insulin resistance is a common feature of the disease. The current approach to treating T2DM is the use of oral antidiabetic agents (OAAs), insulin, and incretin-based drugs in an attempt to achieve glycaemic control and maintain glucose homeostasis. However, conventional anti-T2DM drugs have been shown to have limited efficacies and serious adverse effects. Hence, the need for newer, more efficacious and safer anti-T2DM agents. Sutherlandia frutescens subsp. microphylla is a flowering shrub of the pea family (Fabaceae/Leguminaceae) found mainly in the Western Cape and Karoo regions of Southern Africa. Concoctions of various parts of the plant are used in the management of different ailments including T2DM. However, despite extensive biological and pharmacological studies, few analyses exist of the chemical constituents of S. frutescens and no Triple Time of Flight Liquid Chromatography with Mass Spectrometry (Triple TOF LC/MS/MS) analysis has been performed. The initial aim of this study was to investigate the phytochemical profile of hot aqueous, cold aqueous, 80% ethanolic, 100% ethanolic, 80% methanolic and 100% methanolic extracts of a single source S. frutescens plant material using colorimetric and spectrophotometric analysis. The hot aqueous extractant was found to be the best extractant for S. frutescens, yielding 1.99 g of crude extract from 16 g fresh powdered plant material. This data suggests that application of heat and water as the extractant (hot aqueous) could play a vital role in extraction of bioactive compounds from S. frutescens and also justifies the traditional use of a tea infusion of S. frutescens. Colorimetric analysis revealed the presence of flavonoids, flavonols, tannins, and phenols in all extracts with varying intensity. The organic extracts 100% methanol, 80% and 100% ethanol exhibited high color intensity (+++) for flavonoids and flavonols respectively, while all the extracts exhibited a moderate color intensity (++) for tannins and phenols. Spectrophotometric analysis of S. frutescens extracts revealed that all the organic extracts contained a significantly higher concentration (in mg/g of extract) of flavonols and tannins when compared to the aqueous extracts. All extracts contained approximately equal levels of phenols. These data confirm the presence of all four groups of bioactive phytocompounds in the S. frutescens extracts used in this study, and also confirm that different solvent extractants possess the capability to differentially extract specific groups of phytocompounds. in individual extracts. Further comparison of these compounds with online databases of anti-diabetic phytocompounds led to the preliminary identification of 10 possible anti-diabetic compounds; α-Pinene, Limonene, Sabinene, Carvone, Myricetin, Rutin, Stigmasterol, Emodin, Sarpagine and Hypoglycin B in crude and solid phase extraction (SPE) fractions of S. frutesecens. Furthermore, using two hepatic cell lines (Chang and HepG2) as an in-vtro model system, the anti-T2DM properties of crude aqueous and organic extracts of S. frutescents was investigated and compared. Both aqueous and organic extracts of S. frutescens were found to decrease gluconeogenesis, increase glucose uptake and decrease lipid accumulation (Triacylglycerol, Diacylglycerol, and Monoacylglycerol) in Chang and HepG2 hepatic cell cultures made insulin resistant (IR) following exposure to high concentration of insulin and fructose. Using real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the aqueous and organic extracts of S. frutescens were confirmed to regulate the expression of Vesicle-associated membrane protein 3 (VAMP3), Mitogen-activated protein kinase 8 (MAPK8), and Insulin receptor substrate 1 (IRS1) in insulin resistant hepatic cells. IR-mediated downregulation of VAMP3, MAPK8, and IRS1 mRNA in IR HepG2 hepatic cell cultures was reversed in the presence of aqueous and organic extracts of S. frutescens. The hot aqueous extract displayed the highest activity in all the assays, while all the organic extracts displayed similar potency. In conclusion, this study reports that aqueous and organic extracts of S. frutescens possess numerous anti-diabetic compounds that can be further investigated for the development of new, more efficacious and less toxic anti-diabetic agents. The presence of multiple compounds in a single extract does suggest a synergistic or combinatorial therapeutic effect. These findings support the burgeoning body of in-vivo and in-vitro literature evidence on the anti-diabetic properties of S. frutescens and its use in folklore medicine.
- Full Text:
- Date Issued: 2016
- Authors: Adefuye, Ogheneochuko Janet
- Date: 2016
- Subjects: Medicinal plants -- Africa , Traditional medicine -- Africa , Herbs -- Therapeutic use -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/3549 , vital:20441
- Description: In Africa, the importance of medicinal plants in folklore medicine and their contribution to primary healthcare is well recognized. Across the continent, local herbal mixtures still provide the only therapeutic option for about 80% of the population. The vast floral diversity and the intrinsic ethnobotanical knowledge has been the backbone of localized traditional herbal medical practices. In Africa, an estimated 5400 of the 60000 described plant taxa possess over 16300 therapeutic uses. Similarly, with a therapeutic flora comprising of approximately 650 species, herbal medical practitioners in South Africa, make use of a plethora of plants to treat different human diseases and infections. Over the years, studies have identified numerous plant species with potential against chronic metabolic diseases including type 2 diabetes mellitus (T2DM). Globally, the incidence and prevalence of T2DM have reached epidemic proportions affecting people of all ages, nationalities and ethnicity. Considered the fourth leading cause of deaths by disease, T2DM is a global health crisis with an estimated diagnosis and mortality frequency of 1 every 5 seconds and 1 every 7 seconds respectively. Though the exact pathophysiology of T2DM is not entirely understood, initial peripheral insulin resistance in adipose tissue, liver, and skeletal muscle with subsequent pancreatic β-cell dysfunction resulting from an attempt to compensate for insulin resistance is a common feature of the disease. The current approach to treating T2DM is the use of oral antidiabetic agents (OAAs), insulin, and incretin-based drugs in an attempt to achieve glycaemic control and maintain glucose homeostasis. However, conventional anti-T2DM drugs have been shown to have limited efficacies and serious adverse effects. Hence, the need for newer, more efficacious and safer anti-T2DM agents. Sutherlandia frutescens subsp. microphylla is a flowering shrub of the pea family (Fabaceae/Leguminaceae) found mainly in the Western Cape and Karoo regions of Southern Africa. Concoctions of various parts of the plant are used in the management of different ailments including T2DM. However, despite extensive biological and pharmacological studies, few analyses exist of the chemical constituents of S. frutescens and no Triple Time of Flight Liquid Chromatography with Mass Spectrometry (Triple TOF LC/MS/MS) analysis has been performed. The initial aim of this study was to investigate the phytochemical profile of hot aqueous, cold aqueous, 80% ethanolic, 100% ethanolic, 80% methanolic and 100% methanolic extracts of a single source S. frutescens plant material using colorimetric and spectrophotometric analysis. The hot aqueous extractant was found to be the best extractant for S. frutescens, yielding 1.99 g of crude extract from 16 g fresh powdered plant material. This data suggests that application of heat and water as the extractant (hot aqueous) could play a vital role in extraction of bioactive compounds from S. frutescens and also justifies the traditional use of a tea infusion of S. frutescens. Colorimetric analysis revealed the presence of flavonoids, flavonols, tannins, and phenols in all extracts with varying intensity. The organic extracts 100% methanol, 80% and 100% ethanol exhibited high color intensity (+++) for flavonoids and flavonols respectively, while all the extracts exhibited a moderate color intensity (++) for tannins and phenols. Spectrophotometric analysis of S. frutescens extracts revealed that all the organic extracts contained a significantly higher concentration (in mg/g of extract) of flavonols and tannins when compared to the aqueous extracts. All extracts contained approximately equal levels of phenols. These data confirm the presence of all four groups of bioactive phytocompounds in the S. frutescens extracts used in this study, and also confirm that different solvent extractants possess the capability to differentially extract specific groups of phytocompounds. in individual extracts. Further comparison of these compounds with online databases of anti-diabetic phytocompounds led to the preliminary identification of 10 possible anti-diabetic compounds; α-Pinene, Limonene, Sabinene, Carvone, Myricetin, Rutin, Stigmasterol, Emodin, Sarpagine and Hypoglycin B in crude and solid phase extraction (SPE) fractions of S. frutesecens. Furthermore, using two hepatic cell lines (Chang and HepG2) as an in-vtro model system, the anti-T2DM properties of crude aqueous and organic extracts of S. frutescents was investigated and compared. Both aqueous and organic extracts of S. frutescens were found to decrease gluconeogenesis, increase glucose uptake and decrease lipid accumulation (Triacylglycerol, Diacylglycerol, and Monoacylglycerol) in Chang and HepG2 hepatic cell cultures made insulin resistant (IR) following exposure to high concentration of insulin and fructose. Using real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the aqueous and organic extracts of S. frutescens were confirmed to regulate the expression of Vesicle-associated membrane protein 3 (VAMP3), Mitogen-activated protein kinase 8 (MAPK8), and Insulin receptor substrate 1 (IRS1) in insulin resistant hepatic cells. IR-mediated downregulation of VAMP3, MAPK8, and IRS1 mRNA in IR HepG2 hepatic cell cultures was reversed in the presence of aqueous and organic extracts of S. frutescens. The hot aqueous extract displayed the highest activity in all the assays, while all the organic extracts displayed similar potency. In conclusion, this study reports that aqueous and organic extracts of S. frutescens possess numerous anti-diabetic compounds that can be further investigated for the development of new, more efficacious and less toxic anti-diabetic agents. The presence of multiple compounds in a single extract does suggest a synergistic or combinatorial therapeutic effect. These findings support the burgeoning body of in-vivo and in-vitro literature evidence on the anti-diabetic properties of S. frutescens and its use in folklore medicine.
- Full Text:
- Date Issued: 2016
Antibacterial effects of Alchornea cordifolia (Schumach. and Thonn.) Müll. Arg extracts and compounds on gastrointestinal, skin, respiratory and urinary tract pathogens
- Siwe-Noundou, Xavier, Krause, Rui W M, van Vuuren, Sandy, Tantoh Ndinteh, Derek, Olivier, D K
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, D K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, D K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
Appraising the national road transport system in the light of the South African economic development plan
- Authors: Potgieter, Andries Hendrik
- Date: 2016
- Subjects: Transportation -- South Africa , Economic development -- South Africa , Infrastructure (Economics) -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/3655 , vital:20450
- Description: Since the mid 70’s politicians have realized how important transport has become in the economy of South Africa and the advantages it has on growth, job creation and infrastructure. The result was involvement in the rules and regulations that govern South African transport in our country today. Economic growth has become a critical factor for the survival of economies as well as the future prospects of generations to come. The global recession which had a direct and indirect effect on South Africa has highlighted the importance. The question on how the National Development Plan could have an influence on local and national economic growth has developed as well as what the impact will be of the contribution road transport can make on the growth of the South African society and the economy. When the current road transport sector is taken into consideration, the need for a constructive plan that can assist transporters, drivers and businesses to grow and expand has been identified. The purpose of this study is thus to determine what the current economic situation in the world and in South Africa is as well as how the current political spheres are contributing to the national economy. An in-depth analysis of the National Development Plan has been done with emphasis on the effect on transport in general and the effect on road transport in South Africa. In order to accomplish this objective a detailed literature study was done which highlighted the academics information that pertains to the above mentioned topics. An empirical study that would measure the thought process and feelings about the National Development Plan and road transport has been conducted by means of a questionnaire. The results of the study have indicated that the National Development Plan could be an important tool and could have an enormous positive effect on the overall economic situation of South Africa and its citizens. In addition, the study has revealed that in the long term the effect of the plan could be to the advantage of the road transport sector. Factors that could contribute to the success would be features such as the planned improvements on the main transport corridors, upgrade of infrastructure and the controlling of environmental matters would have give a positive ring to it. On the other hand, recommendations to rectify and improve other issues such as corruption, leadership, maintenance backlogs and stricter laws and policies have been identified that are hindering businesses to grow and expand. Literature and data gained through the empirical study has indicated that the National Development Plan will improve South Africa’s economic situation. Respondents were optimistic about the plan and the overall feeling were that the plan will succeed in improving the road transport sector thus contribute to the National Development Plan objective to eliminate poverty and inequality by 2030.
- Full Text:
- Date Issued: 2016
- Authors: Potgieter, Andries Hendrik
- Date: 2016
- Subjects: Transportation -- South Africa , Economic development -- South Africa , Infrastructure (Economics) -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/3655 , vital:20450
- Description: Since the mid 70’s politicians have realized how important transport has become in the economy of South Africa and the advantages it has on growth, job creation and infrastructure. The result was involvement in the rules and regulations that govern South African transport in our country today. Economic growth has become a critical factor for the survival of economies as well as the future prospects of generations to come. The global recession which had a direct and indirect effect on South Africa has highlighted the importance. The question on how the National Development Plan could have an influence on local and national economic growth has developed as well as what the impact will be of the contribution road transport can make on the growth of the South African society and the economy. When the current road transport sector is taken into consideration, the need for a constructive plan that can assist transporters, drivers and businesses to grow and expand has been identified. The purpose of this study is thus to determine what the current economic situation in the world and in South Africa is as well as how the current political spheres are contributing to the national economy. An in-depth analysis of the National Development Plan has been done with emphasis on the effect on transport in general and the effect on road transport in South Africa. In order to accomplish this objective a detailed literature study was done which highlighted the academics information that pertains to the above mentioned topics. An empirical study that would measure the thought process and feelings about the National Development Plan and road transport has been conducted by means of a questionnaire. The results of the study have indicated that the National Development Plan could be an important tool and could have an enormous positive effect on the overall economic situation of South Africa and its citizens. In addition, the study has revealed that in the long term the effect of the plan could be to the advantage of the road transport sector. Factors that could contribute to the success would be features such as the planned improvements on the main transport corridors, upgrade of infrastructure and the controlling of environmental matters would have give a positive ring to it. On the other hand, recommendations to rectify and improve other issues such as corruption, leadership, maintenance backlogs and stricter laws and policies have been identified that are hindering businesses to grow and expand. Literature and data gained through the empirical study has indicated that the National Development Plan will improve South Africa’s economic situation. Respondents were optimistic about the plan and the overall feeling were that the plan will succeed in improving the road transport sector thus contribute to the National Development Plan objective to eliminate poverty and inequality by 2030.
- Full Text:
- Date Issued: 2016
Aquatic–terrestrial trophic linkages via riverine invertebrates in a South African catchment
- Authors: Moyo, Sydney
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54427 , vital:26564
- Description: Rivers play a vital role in human livelihoods and are likely to undergo substantial alteration due to climate and land use changes from an increasing human population. Mitigating the pressures facing rivers in the world requires scientists and environmental managers to understand the ecological mechanisms, and ultimately the strength, of connections between ecosystems. This understanding of connections between adjacent habitats will enable environmental managers to predict the consequences of perturbing these linkages in the future. In this thesis, aquatic-terrestrial linkages in rivers were investigated using ecologically meaningful variables including abundances, biomasses, stable isotopes and fatty acids. This study is part of a larger project entitled “Connectivity through allochthony: reciprocal links between adjacent aquatic and terrestrial ecosystems in South Africa”, in which a team of researchers assessed a variety of pathways connecting riverine and estuarine systems to land within a catchment in the Eastern Cape, South Africa. I conceptualised the flow of energy within a temperate southern hemisphere river (the Kowie River) within theoretical models of energy flow such as the River Continuum Concept (RCC; presents lotic systems as being longitudinally linked with food webs in shaded headwaters being principally driven by allochthonous energy, with the addition of autochthonous food as a minor carbon source in the lower reaches) and the Riverine Productivity Model (RPM; proposes consumers derive most of their energy from local production of phytoplankton, benthic algae and aquatic plants, as well as directly from riparian zones via terrestrial leaf litter). Using the RCC as a starting point, I collected macroinvertebrates (September 2012 to May 2013) along a longitudinal gradient and grouped them into functional feeding groups (FFGs). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50 – 83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was ≤ 10% across all sites and seasons). The changes in relative abundances of different FFGs did not follow predictions of the RCC along the longitudinal gradient, as there were no correlations of community structure with some physical attributes (stream width, canopy cover, distance of river) that changed along the river continuum. However, FFG abundances were related to water velocity, total dissolved solids and canopy cover. Broadly, the Kowie River data showed that changes in relative abundances of FFGs along the river continuum could not be explained by changes in physical attributes alone, and may be highly influenced by the availability of food and the chemistry of the stream. Analysis of stable carbon (δ13C) and nitrogen (δ15N) isotopes was used to estimate the contributions of algal and land-based production to consumers over space (six sites) and time (November 2012 to September 2013). Carbon contributions determined by the use of mixing models (Stable Isotope Analysis in R) revealed that consumers in the headwater assimilated mainly terrestrially-derived organic matter, with consumers in the middle and lower reaches assimilating autochthonous basal resources (macrophytes and algae). The findings from this river supported aspects of the RCC (at the headwaters; terrestrial organic matter made up 41% of consumer diets), but overall the data supported the predictions of the RPM (local production made the highest contributions of 50 – 86% to all FFGs across all seasons). The carbon isotopes of consumers and their food sources changed substantially every season, indicating that samples of food sources and consumers should be analysed many times throughout the year to capture that variability and to ensure that ephemeral components of the food web are not missed. To validate the findings from the isotope data, fatty acids were used as complementary tracers to determine the contributions of algal versus terrestrial organic matter to the consumers. Fatty acid tracers for terrestrial (Ʃω3/Ʃω6; 18:2ω6; 18:3ω3) vs aquatic (Ʃω3/Ʃω6; 20:5ω3) sources corroborated the findings from the isotope data set, as the mean ratio of Ʃω3/Ʃω6 in consumers was less than one at the headwaters (indicating allochthony), while middle and lower reaches were associated with Ʃω3/Ʃω6 > 1 (indicating autochthony). In addition to the tracer and FFG analyses for examining trophic connections between land and river, the bidirectional exchange of organisms between the riparian zone and the river was assessed using floating pyramidal traps (to measure emergence) and pan traps (for infalling invertebrates) placed at different sites in the river and the biomass in each trap was determined. The exchanges were variable over space and time, with emergence peaking in summer (169 to 1402 mg m-2 day-1) and declining in winter (3 to 28 mg m-2 day-1). Similarly, infalling invertebrates increased in summer (413 to 679 mg m-2 day-1) and declined in winter (11 to 220 mg m-2 day-1). Biomass measurements are indications of quantity that ignore nutritional quality, so I determined the bidirectional flow of invertebrates using absolute concentrations of physiologically important biochemical compounds (essential and polyunsaturated fatty acids). The fluxes of emergent and infalling arthropods peaked in summer (emergence = 0.3 to 18 mg m-2 day-1 and terrestrial infall = 0.3 to 3 mg m-2 day-1) and declined in winter (emergence = 0.01 to 0.51 mg m-2 day-1 and terrestrial infall = 0.01 to 0.03 mg m-2 day-1). However, during some seasons, no significant differences in polyunsaturated fatty acid flux in either direction were observed; this finding indicated the balance of reciprocal subsidisation via reciprocal flows of animals. Factors such as air temperature and algal productivity affected the reciprocal flows between adjacent habitats, with algal productivity being positively related to emergence while air temperature was positively correlated to infalling terrestrial invertebrates. This research enhances the growing body of literature on the function of riverine systems and offers some invaluable information on the flow of energy and the role played by invertebrates in translocating nutrients from terrestrial systems to aquatic systems and vice versa. This study unifies the concepts of the RCC and RPM and shows that these concepts are not limited only to large rivers, but are applicable to small southern temperate rivers too. However, some tenets of the theoretical models were challenged. For example, it challenges the proposition by the RCC that the fine particulate organic matter leaked from upstream breakdown of coarse particulate organic matter is predominantly allochthonous. Additionally, this study showed that in the headwaters, the RPM underestimated the role of autochthony. Overall, the results showed that the Kowie River and its riparian area are intrinsically connected. Once we understand the mechanisms controlling connections and subsidies across ecotones, we can then start to predict the consequences of disruptions to these connections by climate change and/or land use changes. To make predictions about future perturbations to rivers and riparian zones, studies like this, which considers the form and magnitude of subsidies, are needed to provide baseline information. Algal resources (e.g. epiphyton), macrophytes, riparian plants, terrestrial organisms and aquatic organisms all contributed to aquatic and terrestrial linkages in the Kowie River; therefore, it is important to conserve the different components of these ecosystems.
- Full Text:
- Date Issued: 2016
- Authors: Moyo, Sydney
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54427 , vital:26564
- Description: Rivers play a vital role in human livelihoods and are likely to undergo substantial alteration due to climate and land use changes from an increasing human population. Mitigating the pressures facing rivers in the world requires scientists and environmental managers to understand the ecological mechanisms, and ultimately the strength, of connections between ecosystems. This understanding of connections between adjacent habitats will enable environmental managers to predict the consequences of perturbing these linkages in the future. In this thesis, aquatic-terrestrial linkages in rivers were investigated using ecologically meaningful variables including abundances, biomasses, stable isotopes and fatty acids. This study is part of a larger project entitled “Connectivity through allochthony: reciprocal links between adjacent aquatic and terrestrial ecosystems in South Africa”, in which a team of researchers assessed a variety of pathways connecting riverine and estuarine systems to land within a catchment in the Eastern Cape, South Africa. I conceptualised the flow of energy within a temperate southern hemisphere river (the Kowie River) within theoretical models of energy flow such as the River Continuum Concept (RCC; presents lotic systems as being longitudinally linked with food webs in shaded headwaters being principally driven by allochthonous energy, with the addition of autochthonous food as a minor carbon source in the lower reaches) and the Riverine Productivity Model (RPM; proposes consumers derive most of their energy from local production of phytoplankton, benthic algae and aquatic plants, as well as directly from riparian zones via terrestrial leaf litter). Using the RCC as a starting point, I collected macroinvertebrates (September 2012 to May 2013) along a longitudinal gradient and grouped them into functional feeding groups (FFGs). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50 – 83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was ≤ 10% across all sites and seasons). The changes in relative abundances of different FFGs did not follow predictions of the RCC along the longitudinal gradient, as there were no correlations of community structure with some physical attributes (stream width, canopy cover, distance of river) that changed along the river continuum. However, FFG abundances were related to water velocity, total dissolved solids and canopy cover. Broadly, the Kowie River data showed that changes in relative abundances of FFGs along the river continuum could not be explained by changes in physical attributes alone, and may be highly influenced by the availability of food and the chemistry of the stream. Analysis of stable carbon (δ13C) and nitrogen (δ15N) isotopes was used to estimate the contributions of algal and land-based production to consumers over space (six sites) and time (November 2012 to September 2013). Carbon contributions determined by the use of mixing models (Stable Isotope Analysis in R) revealed that consumers in the headwater assimilated mainly terrestrially-derived organic matter, with consumers in the middle and lower reaches assimilating autochthonous basal resources (macrophytes and algae). The findings from this river supported aspects of the RCC (at the headwaters; terrestrial organic matter made up 41% of consumer diets), but overall the data supported the predictions of the RPM (local production made the highest contributions of 50 – 86% to all FFGs across all seasons). The carbon isotopes of consumers and their food sources changed substantially every season, indicating that samples of food sources and consumers should be analysed many times throughout the year to capture that variability and to ensure that ephemeral components of the food web are not missed. To validate the findings from the isotope data, fatty acids were used as complementary tracers to determine the contributions of algal versus terrestrial organic matter to the consumers. Fatty acid tracers for terrestrial (Ʃω3/Ʃω6; 18:2ω6; 18:3ω3) vs aquatic (Ʃω3/Ʃω6; 20:5ω3) sources corroborated the findings from the isotope data set, as the mean ratio of Ʃω3/Ʃω6 in consumers was less than one at the headwaters (indicating allochthony), while middle and lower reaches were associated with Ʃω3/Ʃω6 > 1 (indicating autochthony). In addition to the tracer and FFG analyses for examining trophic connections between land and river, the bidirectional exchange of organisms between the riparian zone and the river was assessed using floating pyramidal traps (to measure emergence) and pan traps (for infalling invertebrates) placed at different sites in the river and the biomass in each trap was determined. The exchanges were variable over space and time, with emergence peaking in summer (169 to 1402 mg m-2 day-1) and declining in winter (3 to 28 mg m-2 day-1). Similarly, infalling invertebrates increased in summer (413 to 679 mg m-2 day-1) and declined in winter (11 to 220 mg m-2 day-1). Biomass measurements are indications of quantity that ignore nutritional quality, so I determined the bidirectional flow of invertebrates using absolute concentrations of physiologically important biochemical compounds (essential and polyunsaturated fatty acids). The fluxes of emergent and infalling arthropods peaked in summer (emergence = 0.3 to 18 mg m-2 day-1 and terrestrial infall = 0.3 to 3 mg m-2 day-1) and declined in winter (emergence = 0.01 to 0.51 mg m-2 day-1 and terrestrial infall = 0.01 to 0.03 mg m-2 day-1). However, during some seasons, no significant differences in polyunsaturated fatty acid flux in either direction were observed; this finding indicated the balance of reciprocal subsidisation via reciprocal flows of animals. Factors such as air temperature and algal productivity affected the reciprocal flows between adjacent habitats, with algal productivity being positively related to emergence while air temperature was positively correlated to infalling terrestrial invertebrates. This research enhances the growing body of literature on the function of riverine systems and offers some invaluable information on the flow of energy and the role played by invertebrates in translocating nutrients from terrestrial systems to aquatic systems and vice versa. This study unifies the concepts of the RCC and RPM and shows that these concepts are not limited only to large rivers, but are applicable to small southern temperate rivers too. However, some tenets of the theoretical models were challenged. For example, it challenges the proposition by the RCC that the fine particulate organic matter leaked from upstream breakdown of coarse particulate organic matter is predominantly allochthonous. Additionally, this study showed that in the headwaters, the RPM underestimated the role of autochthony. Overall, the results showed that the Kowie River and its riparian area are intrinsically connected. Once we understand the mechanisms controlling connections and subsidies across ecotones, we can then start to predict the consequences of disruptions to these connections by climate change and/or land use changes. To make predictions about future perturbations to rivers and riparian zones, studies like this, which considers the form and magnitude of subsidies, are needed to provide baseline information. Algal resources (e.g. epiphyton), macrophytes, riparian plants, terrestrial organisms and aquatic organisms all contributed to aquatic and terrestrial linkages in the Kowie River; therefore, it is important to conserve the different components of these ecosystems.
- Full Text:
- Date Issued: 2016
Are people responsive to a more sustainable, decentralized, and user-driven management of urban metabolism?:
- Chelleri, Lorenzo, Kua, Harn W, Rodriguez Sanchez, Juan P, Nahiduzzaman, Kh M, Thondhlana, Gladman
- Authors: Chelleri, Lorenzo , Kua, Harn W , Rodriguez Sanchez, Juan P , Nahiduzzaman, Kh M , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144299 , vital:38329 , https://orcid.org/0000-0001-8253-0264
- Description: Smart, green, and resilient city paradigms have been mainly promoted through top-down and technocratic approaches. However, based on the notion to return to “the right to the city”, emerging community-driven initiatives are providing self-managed infrastructures contributing to urban sustainability transitions. This paper explores the relevance of the behavioral aspects of people-centered approaches in dealing with two different facets of urban metabolism: physical infrastructure (involvement with the management of decentralized infrastructures) and consumption patterns (involvement in proactive reduction of resources used). In the first case we assessed community perceptions about the roles, benefits, and willingness to proactively engage in the management of decentralized green infrastructures in Bogotá City, Colombia. For the second facet, we measured the effectiveness of change agents in re-shaping energy consumption decisions within urban social networks in South Africa and Saudi Arabia. This paper’s results show that pre-determined and standardized strategies do not guarantee positive, nor homogeneous, results in terms of meeting sustainability targets, or promoting community involvement. Hence, a better integration of people-centered and top-down approaches is needed through context-dependent policies, for enhancing both users’ appreciation of and commitment to urban metabolism participative management.
- Full Text:
- Date Issued: 2016
- Authors: Chelleri, Lorenzo , Kua, Harn W , Rodriguez Sanchez, Juan P , Nahiduzzaman, Kh M , Thondhlana, Gladman
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144299 , vital:38329 , https://orcid.org/0000-0001-8253-0264
- Description: Smart, green, and resilient city paradigms have been mainly promoted through top-down and technocratic approaches. However, based on the notion to return to “the right to the city”, emerging community-driven initiatives are providing self-managed infrastructures contributing to urban sustainability transitions. This paper explores the relevance of the behavioral aspects of people-centered approaches in dealing with two different facets of urban metabolism: physical infrastructure (involvement with the management of decentralized infrastructures) and consumption patterns (involvement in proactive reduction of resources used). In the first case we assessed community perceptions about the roles, benefits, and willingness to proactively engage in the management of decentralized green infrastructures in Bogotá City, Colombia. For the second facet, we measured the effectiveness of change agents in re-shaping energy consumption decisions within urban social networks in South Africa and Saudi Arabia. This paper’s results show that pre-determined and standardized strategies do not guarantee positive, nor homogeneous, results in terms of meeting sustainability targets, or promoting community involvement. Hence, a better integration of people-centered and top-down approaches is needed through context-dependent policies, for enhancing both users’ appreciation of and commitment to urban metabolism participative management.
- Full Text:
- Date Issued: 2016
Art investment in South Africa: portfolio diversification and art market efficiency
- Botha, Ferdi, Snowball, Jeanette D, Scott, Brett
- Authors: Botha, Ferdi , Snowball, Jeanette D , Scott, Brett
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64794 , vital:28601 , http://www.dx.doi.org/10.17159/2222-3436/2016/v19n3a4
- Description: Art has been suggested as a good way to diversify investment portfolios during times of financial uncertainty. The argument is that art exhibits different risk and return characteristics to conventional investments in other asset classes. The new Citadel art price index offered the opportunity to test this theory in the South African context. Moreover, this paper tests whether art prices are efficient. The Citadel index uses the hedonic regression method with observations drawn from the top 100, 50 and 20 artists by sales volume, giving approximately 29 503 total auction observations. The Index consists of quarterly data from the period 2000Q1 to 2013Q3. A vector autoregression of the art price index, Johannesburg stock exchange all-share index, house price index, and South African government bond index were used. Results show that, when there are increased returns on the stock market in a preceding period and wealth increases, there is a change in the Citadel art price index in the same direction. No significant difference was found between the house price index and the art price index, or between the art and government bond price indices. The art market is also found to be inefficient, thereby exacerbating the risk of investing in art. Overall, the South African art market does not offer the opportunity to diversify portfolios dominated by either property, bonds, or shares.
- Full Text:
- Date Issued: 2016
- Authors: Botha, Ferdi , Snowball, Jeanette D , Scott, Brett
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/64794 , vital:28601 , http://www.dx.doi.org/10.17159/2222-3436/2016/v19n3a4
- Description: Art has been suggested as a good way to diversify investment portfolios during times of financial uncertainty. The argument is that art exhibits different risk and return characteristics to conventional investments in other asset classes. The new Citadel art price index offered the opportunity to test this theory in the South African context. Moreover, this paper tests whether art prices are efficient. The Citadel index uses the hedonic regression method with observations drawn from the top 100, 50 and 20 artists by sales volume, giving approximately 29 503 total auction observations. The Index consists of quarterly data from the period 2000Q1 to 2013Q3. A vector autoregression of the art price index, Johannesburg stock exchange all-share index, house price index, and South African government bond index were used. Results show that, when there are increased returns on the stock market in a preceding period and wealth increases, there is a change in the Citadel art price index in the same direction. No significant difference was found between the house price index and the art price index, or between the art and government bond price indices. The art market is also found to be inefficient, thereby exacerbating the risk of investing in art. Overall, the South African art market does not offer the opportunity to diversify portfolios dominated by either property, bonds, or shares.
- Full Text:
- Date Issued: 2016
Assessing authentic leadership and workplace trust amongst managerial government employees in Lesotho
- Authors: Damane, Likeleko
- Date: 2016
- Subjects: Leadership -- Moral and ethical aspects , Industrial management
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/9033 , vital:26458
- Description: In today‘s world, characterised by highly competitive global economies, organisations have realised the need for a positive approach in order to remain competitive, sustainable and to attract and retain talent. A positive approach to leadership and an organisational environment characterised by trust has been one of the fundamental tools towards achieving this goal. The main objective of the present study was to assess the existence of positive organizational approaches (authentic leadership and workplace trust) within the government of Lesotho, especially at a time when the country was facing difficulties. The study was descriptive in nature, and followed a non-experimental quantitative approach. The survey made use of a sample of 153 civil servants occupying positions from supervisory to senior management. Data was acquired through the use of an electronic questionnaire made up of two scales: one was a self-assessment instrument on authentic leadership adopted from Walumbwa and associates, and the other scale was on workplace trust developed by Natalie Ferres. The analysis of data involved descriptive statistics, t-tests, ANOVA, post hoc tests and Cohen‘s d. The results of the study provided evidence that there were high levels of the authentic leadership and trust in the workplace. Demographic variables were not found to influence the outcome of authentic leadership scores, however, education and managerial level were found to have an influence on organisational trust. The findings of the study provoked the researcher to call for an implementation of policy on positive training for management and for further research in this area.
- Full Text:
- Date Issued: 2016
- Authors: Damane, Likeleko
- Date: 2016
- Subjects: Leadership -- Moral and ethical aspects , Industrial management
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/9033 , vital:26458
- Description: In today‘s world, characterised by highly competitive global economies, organisations have realised the need for a positive approach in order to remain competitive, sustainable and to attract and retain talent. A positive approach to leadership and an organisational environment characterised by trust has been one of the fundamental tools towards achieving this goal. The main objective of the present study was to assess the existence of positive organizational approaches (authentic leadership and workplace trust) within the government of Lesotho, especially at a time when the country was facing difficulties. The study was descriptive in nature, and followed a non-experimental quantitative approach. The survey made use of a sample of 153 civil servants occupying positions from supervisory to senior management. Data was acquired through the use of an electronic questionnaire made up of two scales: one was a self-assessment instrument on authentic leadership adopted from Walumbwa and associates, and the other scale was on workplace trust developed by Natalie Ferres. The analysis of data involved descriptive statistics, t-tests, ANOVA, post hoc tests and Cohen‘s d. The results of the study provided evidence that there were high levels of the authentic leadership and trust in the workplace. Demographic variables were not found to influence the outcome of authentic leadership scores, however, education and managerial level were found to have an influence on organisational trust. The findings of the study provoked the researcher to call for an implementation of policy on positive training for management and for further research in this area.
- Full Text:
- Date Issued: 2016
Assessing estuarine nursery habitats for Cape Stumpnose (Rhabdosargus holubi), (Pisces: Sparidae) in a warm-temperate estuary in the Eastern Cape, South Africa
- Authors: Leslie, Timothy David
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3178 , vital:20381
- Description: The nursery role hypothesis provides an approach for assessing the nursery function of habitat types within estuaries. This study attempted to assess the nursery value of the dominant estuarine habitats in the Bushmans Estuary for Rhabdosargus holubi (Steindachner 1881) by analysing habitat complexity, relative abundance and behaviour of R. holubi and using stomach contents analysis and dietary diatom composition as indicative of feeding habitat. Structural habitat complexity was assessed in Zostera capensis (Setchell) seagrass and Spartina maritima (Curtis Fernald) salt marsh by sampling above-ground stem density and length, and total cover per unit area (Ct/At). Dimensionless habitat complexity indices such as the interstitial spatial index (ISI) at three magnifications and fractal geometry at two magnifications were used to further analyse habitat complexity. Above-ground biomass (P<0.05) in each season and canopy height (P<0.001) were significantly higher in salt marsh than in seagrass whilst stem density was significantly higher in seagrass than in salt marsh in each season (P<0.001). Each dimensionless index indicated that complexity is notably higher in seagrass than in the salt marsh. Using dimensionless indices that analyse complexity at different spatial scales provided a better analysis of habitat complexity than canopy height and biomass as it allowed for direct comparisons between habitat types. Underwater video cameras were deployed in seagrass, salt marsh and sand flat habitats to assess the relative abundance and behaviour of R. holubi. The relative abundance of R. holubi was significantly higher in seagrass than salt marsh and sand flats, whilst the behaviour of R. holubi indicated a high degree of habitat use in structured habitats and a low degree of habitat use in unstructured sand flat habitats. This indicated that not only are juvenile R. holubi a vegetation-associated species, but also a species that prefers seagrass to salt marsh.
- Full Text:
- Date Issued: 2016
- Authors: Leslie, Timothy David
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3178 , vital:20381
- Description: The nursery role hypothesis provides an approach for assessing the nursery function of habitat types within estuaries. This study attempted to assess the nursery value of the dominant estuarine habitats in the Bushmans Estuary for Rhabdosargus holubi (Steindachner 1881) by analysing habitat complexity, relative abundance and behaviour of R. holubi and using stomach contents analysis and dietary diatom composition as indicative of feeding habitat. Structural habitat complexity was assessed in Zostera capensis (Setchell) seagrass and Spartina maritima (Curtis Fernald) salt marsh by sampling above-ground stem density and length, and total cover per unit area (Ct/At). Dimensionless habitat complexity indices such as the interstitial spatial index (ISI) at three magnifications and fractal geometry at two magnifications were used to further analyse habitat complexity. Above-ground biomass (P<0.05) in each season and canopy height (P<0.001) were significantly higher in salt marsh than in seagrass whilst stem density was significantly higher in seagrass than in salt marsh in each season (P<0.001). Each dimensionless index indicated that complexity is notably higher in seagrass than in the salt marsh. Using dimensionless indices that analyse complexity at different spatial scales provided a better analysis of habitat complexity than canopy height and biomass as it allowed for direct comparisons between habitat types. Underwater video cameras were deployed in seagrass, salt marsh and sand flat habitats to assess the relative abundance and behaviour of R. holubi. The relative abundance of R. holubi was significantly higher in seagrass than salt marsh and sand flats, whilst the behaviour of R. holubi indicated a high degree of habitat use in structured habitats and a low degree of habitat use in unstructured sand flat habitats. This indicated that not only are juvenile R. holubi a vegetation-associated species, but also a species that prefers seagrass to salt marsh.
- Full Text:
- Date Issued: 2016