The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla under farm conditions
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Onomu , Abigail John
- Date: 2019
- Subjects: Marine algae Algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14682 , vital:40044
- Description: This study investigates the effect of two fresh seaweeds, a formulated diet and different feeding regimes on the growth (weight, diameter and height) and gonad quality (gonadosomatic index, colour, texture, firmness and gonad maturity) of the collector sea urchin, Tripneustes gratilla under farm conditions for eighteen weeks. The gonad enhancement study was divided into two sections. The first section investigated the effect of feeds on the somatic growth and gonad quality for 12 weeks. The feeds investigated during this phase of the study were fresh Ulva (U); a 50:50 mixture of fresh Ulva and Gracilaria (UG); fresh Gracilaria (G) and a formulated diet, which contained 200g of dried Ulva per kg (designated as 20U). The second section or phase of this study started for a period of 6 weeks and investigated the effect of a change of diet on urchins previously fed the various feeds from section 1. The feeding regimes used were (U-20U) i.e urchins previously fed with Ulva were subsequently fed 20U diet, similarly, (UG-20U); (G-20U) and (20U- 20U). For the first section of the experiment, no differences were observed in the growth (weight, diameter and height) of urchins fed both fresh diets and the formulated diet. However, urchins fed the formulated diet produced gonad weight of 50.72 ± 5.4g which was significantly higher (P<0.001) than those fed fresh diets. The gonads of urchins fed the Gracilaria diet were significantly darker (P= 0.023) in colour compared with those examined from urchins fed the formulated diet, but were not significantly different from any of the other fresh diets tested (Ulva and Ulva mixed with Gracilaria). Gonad from each of the feed treatments were similar in terms of the redness (a*) and yellowness (b*) as well as the texture and firmness. The gonad maturities of urchins fed the various diets were not significantly different from each other. By the end of the second section/phase of the study (6 week period following the diet change), somatic growth (weight, height and diameter) of urchins in all treatment groups did not differ significantly from each other (ANOVA, P= 0.784; P= 0.988; P= 0.28 respectively). Gonad weight of urchins in treatment groups UG-20U and G-20U became similar to those fed the 20U diet at the end of the trial (week18). However, the gonad weight of urchins in the 20U treatment group remained significantly greater than urchins in the U-20U group at the end of the trial (Kruskal-Wallis ANOVA, P= 0.002). Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, P= 0.029) than those in the U-20U group after the change of diet. However, gonad lightness (L*) of urchins in treatment groups U-20U and G–20U did not differ significantly from those in the UG-20U and 20U treatment groups. All feed regimes were similar in terms of the gonad‟s redness (a*) and yellowness (b*), texture and firmness as well as gonad maturity at the end of the trial. This gonad enhancement study on wild collected adult T. gratilla has shown that somatic growth (urchin weight, test diameter and height) does not differ between the dietary treatments (fresh seaweeds and a formulated diet) tested in this study. The formulated feed (20U diet) does however enhance gonad growth of T. gratilla under farm conditions, supporting previous laboratory trials conducted on this species fed similar diets, indicating that sea urchins gonad enhancement can be cultured under farm conditions in South Africa.
- Full Text:
- Date Issued: 2019
The effectiveness of the joint building contracts committee principal building agreement in the South African built environment
- Authors: Mokhojane, K’homotho Nester
- Date: 2019
- Subjects: Construction contracts -- South Africa , Buildings -- Specifications -- South Africa , Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42019 , vital:36618
- Description: Government investment in infrastructure development in South Africa is set to increase in the next few years to facilitate its mandate of radical economic transformation; contractually there is no margin for error in the execution of infrastructure projects. With a rising inflation, low economic growth and high unemployment, greater need for service delivery and an ever-increasing level of competition, contractor profit margins on are dwindling year on year. Things should not go wrong during construction but often do which results in serious reputational damage to all members involved, companies being liquidated, leaving workers in a desperate plea for employment and leaving them and their families facing poverty in the face. The choice and understanding of a particular contract is very important. The Joint Building Contracts Committee (JBCC) concentrates primarily on the compilation of contract documentation aimed at an equitable distribution of contractual risk in the building industry. The suite is approved by the Construction Industry Development Board (CIDB) and is used by Local Government, District Municipalities, Provincial and National Departments and the Private Sector. The Principal Building Agreement (PBA) is the cornerstone of the JBCC Suite of documents. For the purpose of the research, only JBCC PBA will be the focus area. Contract documents have to be reviewed and revised regularly. Regular revisions to the JBCC contract documentation suite aim to ensure that available documentation remains current. Construction contracts have evolved into standard contract forms. This is not only because of their advantages of familiarity and the prohibitive cost of customisation but also to provide certainty on the nature of the transaction between the contracting parties on a construction project. The study found that the JBCC PBA Edition 6.1 of March 2014 is not widely used, as stakeholders largely prefer to utilise its predecessors, Edition 4.1 of March 2005 and Edition 5.0 of July 2007. The lack of usage could be attributed to prevailing negative perceptions by the users on the contractual risks involved. The study found that contractual risk is better mitigated than in previous JBCC PBA Editions. Furthermore, there are some areas of concern identified where the JBCC PBA document could be further enhanced to improve its overall effectiveness as a contract management tool. The discovered that the JBCC PBA Edition 6.1 standard form of contract are compiled in the interests of standardisation and aim to portray the consensus concerning good practice and an equitable distribution of contractual risk. The findings will help all stakeholders in the South African Building Industry to better understand the implications, benefits and improve their understanding of the JBCC PBA, especially Construction Project Managers employed by the State at different levels, either Local Government, District Municipality, Provincial Departments and National Departments. It will also be beneficial to Architects, Construction Project Managers, Construction Managers, Quantity Surveyors and Engineers operating as consultants, contractors or academics.
- Full Text:
- Date Issued: 2019
- Authors: Mokhojane, K’homotho Nester
- Date: 2019
- Subjects: Construction contracts -- South Africa , Buildings -- Specifications -- South Africa , Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42019 , vital:36618
- Description: Government investment in infrastructure development in South Africa is set to increase in the next few years to facilitate its mandate of radical economic transformation; contractually there is no margin for error in the execution of infrastructure projects. With a rising inflation, low economic growth and high unemployment, greater need for service delivery and an ever-increasing level of competition, contractor profit margins on are dwindling year on year. Things should not go wrong during construction but often do which results in serious reputational damage to all members involved, companies being liquidated, leaving workers in a desperate plea for employment and leaving them and their families facing poverty in the face. The choice and understanding of a particular contract is very important. The Joint Building Contracts Committee (JBCC) concentrates primarily on the compilation of contract documentation aimed at an equitable distribution of contractual risk in the building industry. The suite is approved by the Construction Industry Development Board (CIDB) and is used by Local Government, District Municipalities, Provincial and National Departments and the Private Sector. The Principal Building Agreement (PBA) is the cornerstone of the JBCC Suite of documents. For the purpose of the research, only JBCC PBA will be the focus area. Contract documents have to be reviewed and revised regularly. Regular revisions to the JBCC contract documentation suite aim to ensure that available documentation remains current. Construction contracts have evolved into standard contract forms. This is not only because of their advantages of familiarity and the prohibitive cost of customisation but also to provide certainty on the nature of the transaction between the contracting parties on a construction project. The study found that the JBCC PBA Edition 6.1 of March 2014 is not widely used, as stakeholders largely prefer to utilise its predecessors, Edition 4.1 of March 2005 and Edition 5.0 of July 2007. The lack of usage could be attributed to prevailing negative perceptions by the users on the contractual risks involved. The study found that contractual risk is better mitigated than in previous JBCC PBA Editions. Furthermore, there are some areas of concern identified where the JBCC PBA document could be further enhanced to improve its overall effectiveness as a contract management tool. The discovered that the JBCC PBA Edition 6.1 standard form of contract are compiled in the interests of standardisation and aim to portray the consensus concerning good practice and an equitable distribution of contractual risk. The findings will help all stakeholders in the South African Building Industry to better understand the implications, benefits and improve their understanding of the JBCC PBA, especially Construction Project Managers employed by the State at different levels, either Local Government, District Municipality, Provincial Departments and National Departments. It will also be beneficial to Architects, Construction Project Managers, Construction Managers, Quantity Surveyors and Engineers operating as consultants, contractors or academics.
- Full Text:
- Date Issued: 2019
The effects of project maturity in university infrastructure development
- Motebele, Matsiababa Solofelang
- Authors: Motebele, Matsiababa Solofelang
- Date: 2019
- Subjects: Construction projects -- Management , Construction industry -- Management Project management Infrastructure (Economics) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41953 , vital:36612
- Description: The level of maturity in project management systems within South African universities is low. The low maturity affects project success. Organisational Project Management Maturity Model (OPM3®) – Third Edition (2013). The study is aimed at investigating and finding solutions to the perceived factors that affect Project Management Maturity at Universities’ infrastructure departments. The literature review indicates that organisations benefit from achieving organisational Project Management Maturity when projects are tied to business strategy and support business goals as opposed to when they are executed randomly (OPM3)- Third Edition (2013). A quantitative method was used to collect and analyse data. One questionnaire was put together and distributed to the targeted receipts, i.e., personnel working at infrastructure departments at South African universities, a web-based questionnaire was used to gather the data. A total of 56 responses were received to analyse the data. The stakeholders that responded were: project managers, portfolio managers, project coordinators, administrators and engineer. The study found that PMBoK and planning are factors that have an impact on Project Maturity. Recommendations were that all personnel implementing projects for University Infrastructure should be trained in earned Value Management to ensure that their PMBoK knowledge is enhanced. Other training that is recommended includes Integration Management, Scope Management, Quality Management, Risk Management, Time Management, Resource Management, Procurement Management, Cost Management and Stakeholder Management.
- Full Text:
- Date Issued: 2019
- Authors: Motebele, Matsiababa Solofelang
- Date: 2019
- Subjects: Construction projects -- Management , Construction industry -- Management Project management Infrastructure (Economics) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41953 , vital:36612
- Description: The level of maturity in project management systems within South African universities is low. The low maturity affects project success. Organisational Project Management Maturity Model (OPM3®) – Third Edition (2013). The study is aimed at investigating and finding solutions to the perceived factors that affect Project Management Maturity at Universities’ infrastructure departments. The literature review indicates that organisations benefit from achieving organisational Project Management Maturity when projects are tied to business strategy and support business goals as opposed to when they are executed randomly (OPM3)- Third Edition (2013). A quantitative method was used to collect and analyse data. One questionnaire was put together and distributed to the targeted receipts, i.e., personnel working at infrastructure departments at South African universities, a web-based questionnaire was used to gather the data. A total of 56 responses were received to analyse the data. The stakeholders that responded were: project managers, portfolio managers, project coordinators, administrators and engineer. The study found that PMBoK and planning are factors that have an impact on Project Maturity. Recommendations were that all personnel implementing projects for University Infrastructure should be trained in earned Value Management to ensure that their PMBoK knowledge is enhanced. Other training that is recommended includes Integration Management, Scope Management, Quality Management, Risk Management, Time Management, Resource Management, Procurement Management, Cost Management and Stakeholder Management.
- Full Text:
- Date Issued: 2019
The extent of urban Green Collar employment, its contribution to poverty alleviation and potential for growth in the Eastern Cape, South Africa
- Authors: King, Andrew
- Date: 2019
- Subjects: Economic development -- Environmental aspects -- South Africa -- Eastern Cape , Poverty prevention -- South Africa -- Eastern Cape , Job creation -- South Africa -- Eastern Cape , Urban ecology (Sociology) -- South Africa -- Eastern Cape , Urban poor -- Employment -- South Africa -- Eastern Cape , Clean energy industries -- Employment -- South Africa -- Eastern Cape , Renewable energy sources -- Government policy -- South Africa -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Open spaces -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115191 , vital:34095
- Description: The aim of this research was to investigate the job provisioning benefits of urban green space (GS), the ability of these jobs to alleviate poverty amongst poor urban households, as well as the potential to increase the number of Green Collar (GC) jobs. According to Lal et al. (2010), Roy et al. (2012) and others, environmental employment or GC jobs, represent the very synergy between social, economic and environmental resilience and sustainability, and have the ability to provide an additional range of goods and services. Data was collected from 12 towns and cities in the Eastern Cape of South Africa, all varying in population, town size and geographic location. Structured employer, employee and resident interviews were used to collect data, which pertained to a number of employment characteristics and employee living conditions. Throughout the sample, 19 different types of jobs were identified, and a total of 17 429 GC employees were counted, sharing a total of approximately R503 million in annual wages. Some GC employees were found to still be in a position of poverty despite employment, while others enjoyed a higher standard of living as a result, although this was largely dependent on the extent of wages and other household and employment attributes. Using lessons learnt from previous chapters, a number of data sources and a creative approach, the potential for growth and improvement in the urban GC sector was discussed, and the way forward involves private, public, informal and civil sector participation and innovation; which will not only enhance environmental and social ecosystem services, but also provide meaningful employment opportunities to the otherwise impoverished. Urban GC jobs should be widely viewed as a useful tool in achieving social, environmental and economic prosperity in urban landscapes (Bowen and Kuralbayeva, 2015).
- Full Text:
- Date Issued: 2019
- Authors: King, Andrew
- Date: 2019
- Subjects: Economic development -- Environmental aspects -- South Africa -- Eastern Cape , Poverty prevention -- South Africa -- Eastern Cape , Job creation -- South Africa -- Eastern Cape , Urban ecology (Sociology) -- South Africa -- Eastern Cape , Urban poor -- Employment -- South Africa -- Eastern Cape , Clean energy industries -- Employment -- South Africa -- Eastern Cape , Renewable energy sources -- Government policy -- South Africa -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Open spaces -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115191 , vital:34095
- Description: The aim of this research was to investigate the job provisioning benefits of urban green space (GS), the ability of these jobs to alleviate poverty amongst poor urban households, as well as the potential to increase the number of Green Collar (GC) jobs. According to Lal et al. (2010), Roy et al. (2012) and others, environmental employment or GC jobs, represent the very synergy between social, economic and environmental resilience and sustainability, and have the ability to provide an additional range of goods and services. Data was collected from 12 towns and cities in the Eastern Cape of South Africa, all varying in population, town size and geographic location. Structured employer, employee and resident interviews were used to collect data, which pertained to a number of employment characteristics and employee living conditions. Throughout the sample, 19 different types of jobs were identified, and a total of 17 429 GC employees were counted, sharing a total of approximately R503 million in annual wages. Some GC employees were found to still be in a position of poverty despite employment, while others enjoyed a higher standard of living as a result, although this was largely dependent on the extent of wages and other household and employment attributes. Using lessons learnt from previous chapters, a number of data sources and a creative approach, the potential for growth and improvement in the urban GC sector was discussed, and the way forward involves private, public, informal and civil sector participation and innovation; which will not only enhance environmental and social ecosystem services, but also provide meaningful employment opportunities to the otherwise impoverished. Urban GC jobs should be widely viewed as a useful tool in achieving social, environmental and economic prosperity in urban landscapes (Bowen and Kuralbayeva, 2015).
- Full Text:
- Date Issued: 2019
The extraction of bioactive compounds from spent coffee grounds and their application in a cosmetic formulation
- Authors: Mdubeki, Ntokozo
- Date: 2019
- Subjects: Bioactive compounds , Plants -- bioactive compounds Plant biotechnology Coffee -- Processing Chemistry, Technical Cosmetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41460 , vital:36485
- Description: Residues obtained during coffee processing, known as spent coffee grounds, are an abundant, low-cost and versatile feedstock for a wide range of high-value biological compounds exhibiting a number of properties which include anti-cellulite and antioxidant properties for skin-care applications. The objective of the present work was to obtain a concentrated extract containing high-value biological methylxanthines and polyphenolic compounds with antioxidant activity from the spent coffee grounds. An investigation of the effect of extraction conditions on the concentration of the bioactive compounds in the extract was done. The recovery of both methylxanthines and the polyphenolic compounds with antioxidant activity was achieved through a one-step extraction method under reduced pressure using a non-toxic solvent blend. Various experimental designs were implemented with the aim of optimising the recovery of the selected bioactive compounds, namely, caffeine, theophylline and theobromine from spent coffee grounds by using solvent blends of water and ethanol. A number of factors considered were: (i) repeatability, (ii) extraction time, (iii) composition of solvent blends, (iv) extraction vacuum (pressure)/temperature settings and (v) operating variables. The results suggested that an optimal recovery of the bioactive compounds will be obtained at a two-hour extraction time with a solvent blend of 100% water to maximise caffeine, theophylline, total phenolic content and percentage antioxidant activity, while extraction of theobromine is optimal using aqueous ethanolic solvent mixtures. The optimal vacuum (pressure) setting was found to be 250 mbar to maximise percentage antioxidant activity. The methylxanthines and total phenolic content were not affected by the vacuum (pressure) and temperature settings. Freezedrying the spent coffee grounds before extraction ensured long-term stability of a reproducible sample and achieved better recovery of the important bioactive compounds. Extraction was performed under reduced pressure in order to reduce solvent reflux temperature and to improve extraction efficiency. The quantitative and qualitative determinations of the above-mentioned high-value compounds were performed by high-performance liquid chromatography (HPLC), which confirmed the presence of the methylxanthines in the extracts. In the extraction of methylxanthines, it was found that caffeine was more abundant in the extract as compared to theophylline and theobromine. The extracts were incorporated into three cosmetic gel formulations. Release studies of caffeine, theobromine and theophylline were performed using the three formulated cosmetic gels with the use of a Franz diffusion cell. It was found that theobromine and theophylline were not detected from the gel samples as they were present in too small amounts in the original extracts and there was no significant difference in the release rates of caffeine when comparing the three different gels. Caffeine was released within 15 minutes. All three gels displayed a pseudoplastic viscosity profile and the different viscosity values of the three gels did not influence the release of caffeine significantly.
- Full Text:
- Date Issued: 2019
- Authors: Mdubeki, Ntokozo
- Date: 2019
- Subjects: Bioactive compounds , Plants -- bioactive compounds Plant biotechnology Coffee -- Processing Chemistry, Technical Cosmetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41460 , vital:36485
- Description: Residues obtained during coffee processing, known as spent coffee grounds, are an abundant, low-cost and versatile feedstock for a wide range of high-value biological compounds exhibiting a number of properties which include anti-cellulite and antioxidant properties for skin-care applications. The objective of the present work was to obtain a concentrated extract containing high-value biological methylxanthines and polyphenolic compounds with antioxidant activity from the spent coffee grounds. An investigation of the effect of extraction conditions on the concentration of the bioactive compounds in the extract was done. The recovery of both methylxanthines and the polyphenolic compounds with antioxidant activity was achieved through a one-step extraction method under reduced pressure using a non-toxic solvent blend. Various experimental designs were implemented with the aim of optimising the recovery of the selected bioactive compounds, namely, caffeine, theophylline and theobromine from spent coffee grounds by using solvent blends of water and ethanol. A number of factors considered were: (i) repeatability, (ii) extraction time, (iii) composition of solvent blends, (iv) extraction vacuum (pressure)/temperature settings and (v) operating variables. The results suggested that an optimal recovery of the bioactive compounds will be obtained at a two-hour extraction time with a solvent blend of 100% water to maximise caffeine, theophylline, total phenolic content and percentage antioxidant activity, while extraction of theobromine is optimal using aqueous ethanolic solvent mixtures. The optimal vacuum (pressure) setting was found to be 250 mbar to maximise percentage antioxidant activity. The methylxanthines and total phenolic content were not affected by the vacuum (pressure) and temperature settings. Freezedrying the spent coffee grounds before extraction ensured long-term stability of a reproducible sample and achieved better recovery of the important bioactive compounds. Extraction was performed under reduced pressure in order to reduce solvent reflux temperature and to improve extraction efficiency. The quantitative and qualitative determinations of the above-mentioned high-value compounds were performed by high-performance liquid chromatography (HPLC), which confirmed the presence of the methylxanthines in the extracts. In the extraction of methylxanthines, it was found that caffeine was more abundant in the extract as compared to theophylline and theobromine. The extracts were incorporated into three cosmetic gel formulations. Release studies of caffeine, theobromine and theophylline were performed using the three formulated cosmetic gels with the use of a Franz diffusion cell. It was found that theobromine and theophylline were not detected from the gel samples as they were present in too small amounts in the original extracts and there was no significant difference in the release rates of caffeine when comparing the three different gels. Caffeine was released within 15 minutes. All three gels displayed a pseudoplastic viscosity profile and the different viscosity values of the three gels did not influence the release of caffeine significantly.
- Full Text:
- Date Issued: 2019
The hepatoprotective capacity of selected natural products from South Africa
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Hepatology , Liver -- Physiology Liver -- Pathophysiology Liver -- Diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43622 , vital:36948
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Hepatology , Liver -- Physiology Liver -- Pathophysiology Liver -- Diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43622 , vital:36948
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
The hepatoprotective capacity of selected natural products from South Africa
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Liver -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43611 , vital:36929
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Liver -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43611 , vital:36929
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
The hypolithic invertebrate community in the eastern Karoo: the role of rock size, microclimate and recolonization
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
The impact of elephants on thicket vegetation and other mammals in the Eastern Cape Province, South Africa
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
The impact of re-establishment practices on tree survival, growth and uniformity in South African eucalypt plantations
- Authors: Hechter, Ullrich
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Forest nurseries -- South Africa -- KwaZulu Natal Forest management -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40338 , vital:36142
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests occupy 1.1% (1.2 million hectares) of the South African land surface, of which 75 000 hectares are re-established each year. Eucalypts are the preferred species in the commercial forestry industry as they have the ability to grow fast. In addition, desirable characteristics from different eucalypt species can be combined to develop hybrids that can be used to further improve productivity. In South Africa, eucalypt plantations are mostly found in the warm temperate and sub-tropical zones situated in the KwaZulu-Natal and Mpumalanga Provinces. Various strategies are used to increase productivity and maximise site occupancy, including genetic tree improvement, site-species matching, optimising stand densities, management for risk (abiotic and biotic), as well as improved silviculture. Intensive silviculture is practiced by forest companies to maximise initial tree survival and reduce the time to canopy closure. This includes practices such as site preparation, slash management, tree protection, pruning and thinning, fertilisation and vegetation management treatments. Of the silvicultural aspects that are important during re-establishment, pitting, plant quality (plant size) and watering techniques/regimes have all been shown to influence short-term stand productivity. Despite research carried out on these individual components, recommendations as to best operating practices are varied and have changed over the years, with the application of these practices also varying across companies. Furthermore, there is limited published information related to the interaction between these practices, as well as any longer-term impacts of these factors on stand productivity. The objective of the present study was to gain an understanding of the impacts of pitting, plant quality (plant size), planting depth and watering on tree survival, growth and uniformity in South African Eucalyptus plantations. The study was carried out using three separate field trial series. In a first experiment, two field trials compared post-establishment performance of eucalypts planted using various pitting methods. The two trials were planted using Eucalyptus grandis and E. grandis x E. nitens on two contrasting sites, one at Greenhill in the KwaZulu-Natal Midlands and one at Vroegeveld in Mpumalanga. Four manual (notch, agricultural hoe, mattock, road pick) and three motor-manual heads (inverted A, Archimedes screw and Mondi-designed pitting head) were used to prepare and determine the effect of pit size/quality on tree survival, growth and uniformity. The notch pit implement created the smallest pit (1 L volume) compared to the other pitting implements (4 – 6 L volumes). For both trials, pitting method did not have a significant impact on the success of re-establishment or longer-term tree performance (6 yrs 7 mos at Greenhill and 3 yrs 7 mos at Vroegeveld). This indicates that for the sites and the species tested, all pitting implements could be considered viable alternatives. Other factors, such as operational costs, efficiency and ergonomics should be considered when selecting appropriate pitting methods together with tree performance. In a second experiment, three field trials were implemented to test three main factors: plant size (small and large); planting depth (standard and deep); and watering (dry and water planting). The eight treatments (2 x 2 x 2 factorial) were replicated four times and laid out in a randomised complete blocks design. The trials were established across a range of site types (Mt Home in Kwazulu-Natal, Vroegeveld in Mpumalanga and Trust in Zululand) in the summer rainfall region of South Africa using various eucalypt genera (E. dunnii, E. grandis x E. nitens and E. grandis x E. urophylla). Tree performance was assessed, with results up to four, six and seven years presented for the different sites. Results show that planting larger plants had the highest overall survival (x̄ = 81%) compared to smaller plants (x̄ = 58%), which also resulted in improved basal area and volume across all sites. Larger plants were able to tolerate a wider range of site conditions, thus providing an advantage for re-establishment. The cost-to-benefit of this however needs to be assessed, particularly in the context of current operational nursery standards. The benefits of deeper planting and applying water at planting are less clear, but appear to be beneficial under water stress conditions, such as on sandy sites when the weather is hot and dry. A third experiment tested the interaction between different methods of pit preparation (manual versus motor-manual), dry versus water planting, and re-watering at periodic intervals. The experiment consisted of one field trial established with E. dunnii in Greytown, KwaZulu-Natal. Twelve treatments (2 x 6 factorial) were replicated four times and laid out in a split-plot design, with the main factor of watering regime forming the whole plots, and pitting method the sub-plots. Differences in pit size, pit quality and tree performance were assessed. Pit dimensions and soil friability for the two pitting treatments were different, but pit volumes were similar (manually prepared pits = 4.7 L; motor-manually prepared pits = 4.4 L). Differences in pit soil moisture content were detected between dry planting (4.1%) and all other treatments (9.9%). Rainfall occurred in week 1 - 4 after planting (55.2 mm). Subsequently re-watering, relative to watering only at planting, was not beneficial. No significant growth differences occurred between the two pitting methods, nor was there any interaction between the main factors (pitting methods x watering regimes). Survival for dry planting (75%) was significantly lower than all the other treatments (92%), with a weakly significant difference in Biomass index (corrected) (BIc) at one year. Different pit qualities, determined by pitting method, will not significantly affect early eucalypt performance. However, the addition of water or hydrogel (as opposed to dry planting) will improve early eucalypt survival and growth. Eucalypt survival, growth and uniformity in South Africa continue to be impacted by an increase in mechanisation, changing climate conditions and the use of unskilled labour. It is therefore necessary to implement silvicultural practices which improve survival, growth and uniformity. Planting seedlings into good quality pits (regardless of pitting method) with water has shown to improve survival. It is also beneficial in terms of survival to plant larger (prime) plants at a deeper depth especially on sites with drought conditions. Despite all the establishment trials which have been implemented under controlled conditions, high mortality is still experienced and could be due to the lack of knowledge on the effects of plant quality and handling on post planting performance (particularly survival). In future, plant quality and handling in combination with various planting densities and the application of plant stress relievers should be considered to improve survival..
- Full Text:
- Date Issued: 2019
- Authors: Hechter, Ullrich
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Forest nurseries -- South Africa -- KwaZulu Natal Forest management -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40338 , vital:36142
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests occupy 1.1% (1.2 million hectares) of the South African land surface, of which 75 000 hectares are re-established each year. Eucalypts are the preferred species in the commercial forestry industry as they have the ability to grow fast. In addition, desirable characteristics from different eucalypt species can be combined to develop hybrids that can be used to further improve productivity. In South Africa, eucalypt plantations are mostly found in the warm temperate and sub-tropical zones situated in the KwaZulu-Natal and Mpumalanga Provinces. Various strategies are used to increase productivity and maximise site occupancy, including genetic tree improvement, site-species matching, optimising stand densities, management for risk (abiotic and biotic), as well as improved silviculture. Intensive silviculture is practiced by forest companies to maximise initial tree survival and reduce the time to canopy closure. This includes practices such as site preparation, slash management, tree protection, pruning and thinning, fertilisation and vegetation management treatments. Of the silvicultural aspects that are important during re-establishment, pitting, plant quality (plant size) and watering techniques/regimes have all been shown to influence short-term stand productivity. Despite research carried out on these individual components, recommendations as to best operating practices are varied and have changed over the years, with the application of these practices also varying across companies. Furthermore, there is limited published information related to the interaction between these practices, as well as any longer-term impacts of these factors on stand productivity. The objective of the present study was to gain an understanding of the impacts of pitting, plant quality (plant size), planting depth and watering on tree survival, growth and uniformity in South African Eucalyptus plantations. The study was carried out using three separate field trial series. In a first experiment, two field trials compared post-establishment performance of eucalypts planted using various pitting methods. The two trials were planted using Eucalyptus grandis and E. grandis x E. nitens on two contrasting sites, one at Greenhill in the KwaZulu-Natal Midlands and one at Vroegeveld in Mpumalanga. Four manual (notch, agricultural hoe, mattock, road pick) and three motor-manual heads (inverted A, Archimedes screw and Mondi-designed pitting head) were used to prepare and determine the effect of pit size/quality on tree survival, growth and uniformity. The notch pit implement created the smallest pit (1 L volume) compared to the other pitting implements (4 – 6 L volumes). For both trials, pitting method did not have a significant impact on the success of re-establishment or longer-term tree performance (6 yrs 7 mos at Greenhill and 3 yrs 7 mos at Vroegeveld). This indicates that for the sites and the species tested, all pitting implements could be considered viable alternatives. Other factors, such as operational costs, efficiency and ergonomics should be considered when selecting appropriate pitting methods together with tree performance. In a second experiment, three field trials were implemented to test three main factors: plant size (small and large); planting depth (standard and deep); and watering (dry and water planting). The eight treatments (2 x 2 x 2 factorial) were replicated four times and laid out in a randomised complete blocks design. The trials were established across a range of site types (Mt Home in Kwazulu-Natal, Vroegeveld in Mpumalanga and Trust in Zululand) in the summer rainfall region of South Africa using various eucalypt genera (E. dunnii, E. grandis x E. nitens and E. grandis x E. urophylla). Tree performance was assessed, with results up to four, six and seven years presented for the different sites. Results show that planting larger plants had the highest overall survival (x̄ = 81%) compared to smaller plants (x̄ = 58%), which also resulted in improved basal area and volume across all sites. Larger plants were able to tolerate a wider range of site conditions, thus providing an advantage for re-establishment. The cost-to-benefit of this however needs to be assessed, particularly in the context of current operational nursery standards. The benefits of deeper planting and applying water at planting are less clear, but appear to be beneficial under water stress conditions, such as on sandy sites when the weather is hot and dry. A third experiment tested the interaction between different methods of pit preparation (manual versus motor-manual), dry versus water planting, and re-watering at periodic intervals. The experiment consisted of one field trial established with E. dunnii in Greytown, KwaZulu-Natal. Twelve treatments (2 x 6 factorial) were replicated four times and laid out in a split-plot design, with the main factor of watering regime forming the whole plots, and pitting method the sub-plots. Differences in pit size, pit quality and tree performance were assessed. Pit dimensions and soil friability for the two pitting treatments were different, but pit volumes were similar (manually prepared pits = 4.7 L; motor-manually prepared pits = 4.4 L). Differences in pit soil moisture content were detected between dry planting (4.1%) and all other treatments (9.9%). Rainfall occurred in week 1 - 4 after planting (55.2 mm). Subsequently re-watering, relative to watering only at planting, was not beneficial. No significant growth differences occurred between the two pitting methods, nor was there any interaction between the main factors (pitting methods x watering regimes). Survival for dry planting (75%) was significantly lower than all the other treatments (92%), with a weakly significant difference in Biomass index (corrected) (BIc) at one year. Different pit qualities, determined by pitting method, will not significantly affect early eucalypt performance. However, the addition of water or hydrogel (as opposed to dry planting) will improve early eucalypt survival and growth. Eucalypt survival, growth and uniformity in South Africa continue to be impacted by an increase in mechanisation, changing climate conditions and the use of unskilled labour. It is therefore necessary to implement silvicultural practices which improve survival, growth and uniformity. Planting seedlings into good quality pits (regardless of pitting method) with water has shown to improve survival. It is also beneficial in terms of survival to plant larger (prime) plants at a deeper depth especially on sites with drought conditions. Despite all the establishment trials which have been implemented under controlled conditions, high mortality is still experienced and could be due to the lack of knowledge on the effects of plant quality and handling on post planting performance (particularly survival). In future, plant quality and handling in combination with various planting densities and the application of plant stress relievers should be considered to improve survival..
- Full Text:
- Date Issued: 2019
The influence of artificial light on the foraging efficiency and diet of insect eating bats
- Authors: Bailey, Lauren
- Date: 2019
- Subjects: Predation (Biology) , Bats -- Effect of light on , Bats -- Nutrition , Moths
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76376 , vital:30555
- Description: Artificial light may be altering the interactions between bats and moth prey. Unable to make use of bat evasion strategies around artificial light, eared moths are susceptible to exploitation by syntonic bats (using echolocation frequencies between 20-50 kHz within the hearing range of eared moths). Using a handheld plasma metabolite analyzer, I evaluated the foraging success of syntonic bats and rarer allotonic bats (using echolocation frequencies outside the hearing range of eared moths), in areas with artificial light and in areas of natural darkness. I used microscope diet analysis to determine whether bats were consuming more or fewer moths in areas with artificial light and in areas of natural darkness. Syntonic bats were more selective for moth prey under lit conditions, likely owing to a reduction in the ability of tympanate moths to evade bats. Moths increased in the diets of generalist syntonic bats (Pipistrellus hesperidus) foraging around artificial light sources. Some P. hesperidus individuals showed high β-hydroxybutyrate levels around lights, but there was no difference in β-hydroxybutyrate levels between lit and unlit conditions. There is insufficient evidence to reject the null hypothesis that the foraging success of syntonic bats is equivalent in lit vs unlit conditions. The foraging success and diets of allotonic bats, Rhinolophus capensis, appear to be negligibly impacted by artificial light on a small scale. My study emphasizes the need for a mechanistic understanding of the influence of artificial light on the foraging success of bat species. Bat-moth interactions may be influenced by other factors apart from the common assumption that increased refuelling rates will occur in syntonic species foraging on moths around artificial light.
- Full Text:
- Date Issued: 2019
- Authors: Bailey, Lauren
- Date: 2019
- Subjects: Predation (Biology) , Bats -- Effect of light on , Bats -- Nutrition , Moths
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76376 , vital:30555
- Description: Artificial light may be altering the interactions between bats and moth prey. Unable to make use of bat evasion strategies around artificial light, eared moths are susceptible to exploitation by syntonic bats (using echolocation frequencies between 20-50 kHz within the hearing range of eared moths). Using a handheld plasma metabolite analyzer, I evaluated the foraging success of syntonic bats and rarer allotonic bats (using echolocation frequencies outside the hearing range of eared moths), in areas with artificial light and in areas of natural darkness. I used microscope diet analysis to determine whether bats were consuming more or fewer moths in areas with artificial light and in areas of natural darkness. Syntonic bats were more selective for moth prey under lit conditions, likely owing to a reduction in the ability of tympanate moths to evade bats. Moths increased in the diets of generalist syntonic bats (Pipistrellus hesperidus) foraging around artificial light sources. Some P. hesperidus individuals showed high β-hydroxybutyrate levels around lights, but there was no difference in β-hydroxybutyrate levels between lit and unlit conditions. There is insufficient evidence to reject the null hypothesis that the foraging success of syntonic bats is equivalent in lit vs unlit conditions. The foraging success and diets of allotonic bats, Rhinolophus capensis, appear to be negligibly impacted by artificial light on a small scale. My study emphasizes the need for a mechanistic understanding of the influence of artificial light on the foraging success of bat species. Bat-moth interactions may be influenced by other factors apart from the common assumption that increased refuelling rates will occur in syntonic species foraging on moths around artificial light.
- Full Text:
- Date Issued: 2019
The influence of briefing on Eastern Cape government project outcomes
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Government projects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44562 , vital:38128
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Government projects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44562 , vital:38128
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
The influence of briefing on Eastern Cape government project outcomes
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Project management -- South Africa -- Eastern Cape , Construction industry -- South Africa -- Eastern Cape Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44895 , vital:38186
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Project management -- South Africa -- Eastern Cape , Construction industry -- South Africa -- Eastern Cape Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44895 , vital:38186
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
The influence of hands-on chemistry experimental interventions on the attitudes of grade 9 learners toward natural science
- Authors: Swartbooi Tarryn Beatrix
- Date: 2019
- Subjects: Chemistry -- Study and teaching
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44628 , vital:38168
- Description: The primary purpose of this research was to explore the influence that interactive, hands-on chemistry experiments may have on grade 9 learners’ attitudes toward Natural Sciences. A pragmatic research philosophy was used to best answer the research question which asked “Do hands-on chemistry interventions have a positive effect on grade 9 learners cognitive, affective and behavioural attitude toward Natural Sciences?” and explore the problem statement “The conducting of relevant hands-on chemistry experiments and demonstrations are expected to positively affect learners’ attitudes (cognitive, affective and behavioural), which would in turn motivate learners to further explore science, both in and outside of the classrooms and increase their interest”. The attitudes of learners were studied at two quintile-1 ranked schools both situated in lower socio-economic areas. The main findings that for cognitive attitude from the achievement tests were that Quintile-1 schools based in low socio-economic areas have similar cognitive attitude outcomes (pre-tests, post-tests) except for scientific language. In addition, according to multiple linear regression testing, the hands-on chemistry intervention group (test group) had a more uniform understanding of the scientific topic under study when compared to the traditionally taught group of learners (control group). Key findings from the survey and focus group for affective attitude (School A n=56 and School B n=14) showed that most of the learners responded that science interests them. They also responded that they wanted science club as a permanent fixture at their school and enjoyed doing experiments practically. Main findings for the behavioural attitudes from the focus group and survey were that hands on chemistry experiments motivated grade 9 learners to select Physical Sciences in grade 10 and it also encouraged them to want follow a career in science. From the survey responses it was inferred that learners’ behavioural attitude (BA) toward science was positively affected by science demonstrations and experiments.
- Full Text:
- Date Issued: 2019
- Authors: Swartbooi Tarryn Beatrix
- Date: 2019
- Subjects: Chemistry -- Study and teaching
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44628 , vital:38168
- Description: The primary purpose of this research was to explore the influence that interactive, hands-on chemistry experiments may have on grade 9 learners’ attitudes toward Natural Sciences. A pragmatic research philosophy was used to best answer the research question which asked “Do hands-on chemistry interventions have a positive effect on grade 9 learners cognitive, affective and behavioural attitude toward Natural Sciences?” and explore the problem statement “The conducting of relevant hands-on chemistry experiments and demonstrations are expected to positively affect learners’ attitudes (cognitive, affective and behavioural), which would in turn motivate learners to further explore science, both in and outside of the classrooms and increase their interest”. The attitudes of learners were studied at two quintile-1 ranked schools both situated in lower socio-economic areas. The main findings that for cognitive attitude from the achievement tests were that Quintile-1 schools based in low socio-economic areas have similar cognitive attitude outcomes (pre-tests, post-tests) except for scientific language. In addition, according to multiple linear regression testing, the hands-on chemistry intervention group (test group) had a more uniform understanding of the scientific topic under study when compared to the traditionally taught group of learners (control group). Key findings from the survey and focus group for affective attitude (School A n=56 and School B n=14) showed that most of the learners responded that science interests them. They also responded that they wanted science club as a permanent fixture at their school and enjoyed doing experiments practically. Main findings for the behavioural attitudes from the focus group and survey were that hands on chemistry experiments motivated grade 9 learners to select Physical Sciences in grade 10 and it also encouraged them to want follow a career in science. From the survey responses it was inferred that learners’ behavioural attitude (BA) toward science was positively affected by science demonstrations and experiments.
- Full Text:
- Date Issued: 2019
The integration of effluent treatment using constructed wetlands, with crop production and aquaculture
- Authors: de Jong, Martyn
- Date: 2019
- Subjects: Recycling (Waste, etc.) , Brewery waste , Sewage -- Purification , Beets , Mozambique tilapia
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95767 , vital:31197
- Description: Breweries are major consumers of water and produce nutrient rich wastewater. Therefore, it is important to research technologies that optimise the reuse and recycling of this waste. This study compared different constructed wetlands (CWs) in terms of their potential for cleaning brewery effluent and simultaneously producing crops Beta vulgaris and fish Oreochromis mossambicus. Filling and draining times (FDT; 15 min, 30 min and 60 min) in tidal CWs were compared in Experiment 1. The 15 min FDT (6.52 ± 0.09 mg/l) and 30 min FDT (5.74 ± 0.09 mg/l) had higher dissolved oxygen (DO) than the 60 min FDT (5.40 ± 0.09 mg/l; p<0.05). This resulted in the 15 and 30 min FDT treatments reaching ammonia effluent discharge standards sooner than the 60 min FDT. Total plant harvest increased with increasing FDT; therefore, 15 min FDT was used as the FDT in tidal treatments in the following experiments. The aerated CW (5.81 ± 0.07 mg/l) and tidal CW (5.67 ± 0.07 mg/l) treatments had higher DO concentrations than the unaerated CW treatment (3.76 ± 0.07 mg/l; p<0.05) in Experiment 2. This resulted in lower ammonia concentrations on day 5 in the aerated and tidal CWs compared with the unaerated treatment (p<0.05). The tidal CW (23.97 ± 2.57 kg) had a total harvest that was approximately four times higher than the unaerated CW (p<0.05), which had the highest frequency of chlorosis and plant mortality; and was unable to treat ammonia to discharge standards. In Experiment 3, the aerated and tidal CW were compared with municipal-water as water sources for aquaculture. There were no differences in fish growth (p > 0.05). However, there were differences in water quality; with the municipal treatment having the lowest pH, EC and nitrate concentration (p<0.05); but all water quality parameters remained in a range suitably for fish production. Due to the tidal CW having the highest plant harvest and lowest frequency of chlorosis and mortality; it was the most suitable CW technology to clean the brewery effluent, and to produce B. vulgaris and water that could be used downstream in aquaculture.
- Full Text:
- Date Issued: 2019
- Authors: de Jong, Martyn
- Date: 2019
- Subjects: Recycling (Waste, etc.) , Brewery waste , Sewage -- Purification , Beets , Mozambique tilapia
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95767 , vital:31197
- Description: Breweries are major consumers of water and produce nutrient rich wastewater. Therefore, it is important to research technologies that optimise the reuse and recycling of this waste. This study compared different constructed wetlands (CWs) in terms of their potential for cleaning brewery effluent and simultaneously producing crops Beta vulgaris and fish Oreochromis mossambicus. Filling and draining times (FDT; 15 min, 30 min and 60 min) in tidal CWs were compared in Experiment 1. The 15 min FDT (6.52 ± 0.09 mg/l) and 30 min FDT (5.74 ± 0.09 mg/l) had higher dissolved oxygen (DO) than the 60 min FDT (5.40 ± 0.09 mg/l; p<0.05). This resulted in the 15 and 30 min FDT treatments reaching ammonia effluent discharge standards sooner than the 60 min FDT. Total plant harvest increased with increasing FDT; therefore, 15 min FDT was used as the FDT in tidal treatments in the following experiments. The aerated CW (5.81 ± 0.07 mg/l) and tidal CW (5.67 ± 0.07 mg/l) treatments had higher DO concentrations than the unaerated CW treatment (3.76 ± 0.07 mg/l; p<0.05) in Experiment 2. This resulted in lower ammonia concentrations on day 5 in the aerated and tidal CWs compared with the unaerated treatment (p<0.05). The tidal CW (23.97 ± 2.57 kg) had a total harvest that was approximately four times higher than the unaerated CW (p<0.05), which had the highest frequency of chlorosis and plant mortality; and was unable to treat ammonia to discharge standards. In Experiment 3, the aerated and tidal CW were compared with municipal-water as water sources for aquaculture. There were no differences in fish growth (p > 0.05). However, there were differences in water quality; with the municipal treatment having the lowest pH, EC and nitrate concentration (p<0.05); but all water quality parameters remained in a range suitably for fish production. Due to the tidal CW having the highest plant harvest and lowest frequency of chlorosis and mortality; it was the most suitable CW technology to clean the brewery effluent, and to produce B. vulgaris and water that could be used downstream in aquaculture.
- Full Text:
- Date Issued: 2019
The invasion ecology of Nymphaea mexicana Zucc. (Mexican Water lily) in South Africa
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
The medicinal chemistry of selected halogenated diketopiperazines CYCLO(CIS-PRO-4F-PRO) and CYCLO(L-PHE-4I-VAL)
- Authors: Dakada, Vuyokazi
- Date: 2019
- Subjects: Medicinal plants , Drug development Cells -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39370 , vital:35221
- Description: Generally, peptides are selective and efficacious compounds; as a result, they are the best candidates for drug discovery and development. Most peptide-based drugs have been approved for clinical use. The 2,5-Diketopiperazines (DKPs), also known as cyclic dipeptides, are simple compounds which come from nature. Many DKPs are extracted from animals and plants. For example, cyclo(Proline(Pro)-Leucine(Leu)), cyclo(Proline-Valine(Val)), cyclo(Proline-Phenylalanine(Phe)) etc. In this study cyclo(cis-Proline(Pro)-4F-Proline(Pro)) and cyclo(L- Phenylalanine(Phe)-4I- Valine (Val)) were synthesized from their linear esters using a method modified by Milne et al. (1992). This method yielded good results. However, cyclo(L-Phe-4I-Val) degraded due to physicochemical stability attributes caused by hygroscopicity and photosensitivity. Quantitative analysis and evaluation of physicochemical properties of each dipeptide was achieved by using scanning electron microscopy, thermal analysis (differential scanning calorimetry and thermogravimetric analysis) and X-ray powder diffraction. To determine the purity of the cyclic dipeptide, high performance liquid chromatography and thin layer chromatography was used. The structural elucidation of the cyclic dipeptides was carried by employing infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy and, molecular modelling and computational chemistry. The aim of this research was to discover possible biological activity of cyclo(cis-Pro-4-F-Pro) and cyclo(L-Phe-4I-Val) with respect to their antimicrobial, anticancer, anti-diabetic and haematological effects. Cyclo(cis-Pro-4Fluoro-Pro) had no inhibitory effect on the antimicrobial strains tested, and cyclo(L-Phe-4Iodo-Val) could not be tested as the compound decomposed.
- Full Text:
- Date Issued: 2019
- Authors: Dakada, Vuyokazi
- Date: 2019
- Subjects: Medicinal plants , Drug development Cells -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39370 , vital:35221
- Description: Generally, peptides are selective and efficacious compounds; as a result, they are the best candidates for drug discovery and development. Most peptide-based drugs have been approved for clinical use. The 2,5-Diketopiperazines (DKPs), also known as cyclic dipeptides, are simple compounds which come from nature. Many DKPs are extracted from animals and plants. For example, cyclo(Proline(Pro)-Leucine(Leu)), cyclo(Proline-Valine(Val)), cyclo(Proline-Phenylalanine(Phe)) etc. In this study cyclo(cis-Proline(Pro)-4F-Proline(Pro)) and cyclo(L- Phenylalanine(Phe)-4I- Valine (Val)) were synthesized from their linear esters using a method modified by Milne et al. (1992). This method yielded good results. However, cyclo(L-Phe-4I-Val) degraded due to physicochemical stability attributes caused by hygroscopicity and photosensitivity. Quantitative analysis and evaluation of physicochemical properties of each dipeptide was achieved by using scanning electron microscopy, thermal analysis (differential scanning calorimetry and thermogravimetric analysis) and X-ray powder diffraction. To determine the purity of the cyclic dipeptide, high performance liquid chromatography and thin layer chromatography was used. The structural elucidation of the cyclic dipeptides was carried by employing infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy and, molecular modelling and computational chemistry. The aim of this research was to discover possible biological activity of cyclo(cis-Pro-4-F-Pro) and cyclo(L-Phe-4I-Val) with respect to their antimicrobial, anticancer, anti-diabetic and haematological effects. Cyclo(cis-Pro-4Fluoro-Pro) had no inhibitory effect on the antimicrobial strains tested, and cyclo(L-Phe-4Iodo-Val) could not be tested as the compound decomposed.
- Full Text:
- Date Issued: 2019
The morphological and molecular variation of southern African Nannocharax (Characiformes: Distichodontidae), and its taxonomic implications
- Authors: Smith, Timothy
- Date: 2019
- Subjects: Nannocharax -- Africa, Southern , Distichodontidae -- Africa, Southern , Freshwater fishes -- Africa, Southern , Nannocharax -- Genetics -- Africa, Southern , Distichodontidae -- Genetics -- Africa, Southern , Freshwater fishes -- Genetics -- Africa, Southern
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69212 , vital:29446
- Description: Nannocharax is the most species rich genus in the family Distichodontidae, being currently represented by 41 species. The genus is widely distributed across much of sub-Saharan Africa, with a range extending from the Zambezi ichthyofaunal province in the south to the Nilo-Sudan ichthyofaunal province in the north. In southern Africa, the genus is currently represented by four species, Nannocharax dageti Jerep, Vari, & Vreven, 2014, N. machadoi (Poll, 1967), N. macropterus Pellegrin, 1926, and N. multifasciatus Boulenger, 1923. Each of these species exhibit considerable intraspecific pigmentation pattern variation across their respective distribution ranges, suggesting that the current taxonomy possibly underestimates the taxonomic diversity of Nannocharax species in southern Africa. Much pigmentation pattern variation within these southern African species has been observed by both collectors and scientists in the field, prompting an investigation into the extent of this morphological variation as well as what molecular variation may occur as well. The genus displays a high degree of morphological conservatisim, making it difficult to assign external morphological characters as diagnostic. To this end, this study was conducted to determine the extent of diversity of this genus in the region, employing an integrative approach with traditional morphological analysis techniques as well as sequencing the ‘barcoding gene’, cytochrome oxidase I, testing the hypothesis that there is a greater, hidden diversity of this genus in the region than currently recognised. This study aims to identify these potential lineages and accurately map their distributions. Phylogenetic analyses were performed using maximum parsimony, maximum likelihood, and Bayesian inference, using the mitochondrial cytochrome oxidase I gene region. Massive genetic divergence was detected between populations of taxa previously considered to be singular, widely distributed species. The three approaches of phylogenetic inference used in this study yielded trees of comparable overall topology, with the exception of the maximum parsimony tree which indicated additional lineages within the southern African N. multifasciatus group. These analyses revealed four deeply divergent (1.3 – 12.3%) lineages within southern African N. macropterus, as well as two deeply divergent (0.4-14.6%) populations from the Congo ichthyofaunal region, the lineages here named “N. macropterus Congo 1” and “N. macropterus Congo 2”. Within the southern African region, two deeply divergent (10.3%) lineages of N. macropterus were identified from the Okavango River system, identified as “N. macropterus Okavango 2” lineage restricted to the Cuito-Canavale tributary, and “N. macropterus Okavango 1” distributed throughout the remainder of the Okavango system. “N. macropterus Okavango 2” shares a closer relationship with the unique lineage from the Kwanza ichthyofaunal region, named N. macropterus “Kwanza”, which itself is deeply divergent from the N. macropterus “Okavango 1”, N. macropterus “Zambezi”, N. macropterus “Congo 1” and N. macropterus “Congo 2” lineages (3.1-14.4%). Principal component analyses (PCA) and discriminant function analyses (DFA) produced overlapping clusters for all identified lineages, with the exception of the N. macropterus “Kwanza” lineage, which in all analyses clustered away from the other lineages. Analysis of variance (ANOVA) and Kruskall-Wallis tests indicated significant differences in means between character traits between lineages, however, overlap in measurements and counts occurred in all instances except between the N. macropterus “Kwanza” and N. macropterus Congo lineages. However the N. macropterus “Kwanza” lineages could be distinguished from the other lineages by generally smaller fin lengths (dorsal fin 19.5%SL vs 20.0-22.1%SL in others; pectoral fin 16.5%SL vs 20.6-21.8%SL in others; pelvic fin 18.3%SL vs 21.3-22.4) and pigmentation pattern differences. The N. macropterus species group displayed extensive pigmentation pattern variation, to the extent that five pattern grades could be used to classify them. These pattern grades, while not specific to river systems, showed patterns similar to that which was seen in the molecular analyses and could be linked to lineages with only minor overlap between them. Three lineages of N. multifasciatus were identified, with two occurring in the southern African region, each corresponding to a river system, being the N. multifasciatus “Zambezi” and N. multifasciatus “Okavango” lineages. This species group displayed shallower divergence between lineages than did the N. macropterus group, at 2.5% genetic distance. Genetic analysis inferred a closer relationship between the N. multifasciatus “Zambezi” and N. multifasciatus “Congo” lineages than with the N. multifasciatus “Okavango” lineage. Morphological PCA and DFA analyses indicated morphological divergence of the N. multifasciatus “Congo” lineage, with generally larger proportional measurements than southern African specimens (body width 12.6%SL vs 9.5-9.7%SL; body depth 26.6%SL vs 21.6-21.9%SL; head width 12.0%SL vs 10.0-10.4%SL). PCA, DFA, and measurements show a near complete overlap between the N. multifasciatus “Okavango” and N. multifasciatus “Zambezi” lineages. Pigmentation pattern variation occurred within this group, but none that could be assigned to a particular lineage. The N. machadoi species group in southern Africa consists of five lineages: N. machadoi “Zambezi 1”, N. machadoi “Zambezi 2”, N. machadoi “Kafue 1”, N. machadoi “Kafue 2”, and N. machadoi “Okavango”. This group displayed shallower genetic divergence between lineages than the other southern African Nannocharax species groups (0.4-1.3%). This shallow genetic divergence is paralleled by near complete morphological overlap, with PCA and DFA producing overlapping clusters, and measurements, meristics, and pigmentation pattern metrics consisting of very similar values for the lineages. These results indicate that what is considered to be “N. macropterus” in southern Africa should not be named as such. The N. macropterus “Zambezi” and the N. macropterus “Okavango 1” lineages, are misidentifications of Nannocharax dageti. Other “N. macropterus” from the southern African region possesses fewer circumpeduncular scales than the true N. macropterus as described by Pellegrin (1926), and require taxonomic re-evaluation, each here being recognised as a unique lineage with species status, here named N. macropterus “Okavango 2” and N. macropterus “Kwanza”. In particular, N. macropterus “Kwanza” displays deep genetic divergence as well as morphological dissimilarity with the other southern African “N. macropterus” groups. Nannocharax fasciolaris and N. monardi are here placed as junior synonyms of N. multifasciatus, owing to vast overlaps in measurements and character counts of these species and N. multifasciatus, which is also known to occur within the same geographical distribution, as well as dubious arguments from the original publications in delineating these species from N. multifasciatus. Therefore, there is insufficient evidence indicating the presence of multiple species originating from the Okavango system, where it is here indicated that only a single lineage of banded, adipose fin-bearing Nannocharax occurs, namely N. multifasciatus “Okavango”.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Timothy
- Date: 2019
- Subjects: Nannocharax -- Africa, Southern , Distichodontidae -- Africa, Southern , Freshwater fishes -- Africa, Southern , Nannocharax -- Genetics -- Africa, Southern , Distichodontidae -- Genetics -- Africa, Southern , Freshwater fishes -- Genetics -- Africa, Southern
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69212 , vital:29446
- Description: Nannocharax is the most species rich genus in the family Distichodontidae, being currently represented by 41 species. The genus is widely distributed across much of sub-Saharan Africa, with a range extending from the Zambezi ichthyofaunal province in the south to the Nilo-Sudan ichthyofaunal province in the north. In southern Africa, the genus is currently represented by four species, Nannocharax dageti Jerep, Vari, & Vreven, 2014, N. machadoi (Poll, 1967), N. macropterus Pellegrin, 1926, and N. multifasciatus Boulenger, 1923. Each of these species exhibit considerable intraspecific pigmentation pattern variation across their respective distribution ranges, suggesting that the current taxonomy possibly underestimates the taxonomic diversity of Nannocharax species in southern Africa. Much pigmentation pattern variation within these southern African species has been observed by both collectors and scientists in the field, prompting an investigation into the extent of this morphological variation as well as what molecular variation may occur as well. The genus displays a high degree of morphological conservatisim, making it difficult to assign external morphological characters as diagnostic. To this end, this study was conducted to determine the extent of diversity of this genus in the region, employing an integrative approach with traditional morphological analysis techniques as well as sequencing the ‘barcoding gene’, cytochrome oxidase I, testing the hypothesis that there is a greater, hidden diversity of this genus in the region than currently recognised. This study aims to identify these potential lineages and accurately map their distributions. Phylogenetic analyses were performed using maximum parsimony, maximum likelihood, and Bayesian inference, using the mitochondrial cytochrome oxidase I gene region. Massive genetic divergence was detected between populations of taxa previously considered to be singular, widely distributed species. The three approaches of phylogenetic inference used in this study yielded trees of comparable overall topology, with the exception of the maximum parsimony tree which indicated additional lineages within the southern African N. multifasciatus group. These analyses revealed four deeply divergent (1.3 – 12.3%) lineages within southern African N. macropterus, as well as two deeply divergent (0.4-14.6%) populations from the Congo ichthyofaunal region, the lineages here named “N. macropterus Congo 1” and “N. macropterus Congo 2”. Within the southern African region, two deeply divergent (10.3%) lineages of N. macropterus were identified from the Okavango River system, identified as “N. macropterus Okavango 2” lineage restricted to the Cuito-Canavale tributary, and “N. macropterus Okavango 1” distributed throughout the remainder of the Okavango system. “N. macropterus Okavango 2” shares a closer relationship with the unique lineage from the Kwanza ichthyofaunal region, named N. macropterus “Kwanza”, which itself is deeply divergent from the N. macropterus “Okavango 1”, N. macropterus “Zambezi”, N. macropterus “Congo 1” and N. macropterus “Congo 2” lineages (3.1-14.4%). Principal component analyses (PCA) and discriminant function analyses (DFA) produced overlapping clusters for all identified lineages, with the exception of the N. macropterus “Kwanza” lineage, which in all analyses clustered away from the other lineages. Analysis of variance (ANOVA) and Kruskall-Wallis tests indicated significant differences in means between character traits between lineages, however, overlap in measurements and counts occurred in all instances except between the N. macropterus “Kwanza” and N. macropterus Congo lineages. However the N. macropterus “Kwanza” lineages could be distinguished from the other lineages by generally smaller fin lengths (dorsal fin 19.5%SL vs 20.0-22.1%SL in others; pectoral fin 16.5%SL vs 20.6-21.8%SL in others; pelvic fin 18.3%SL vs 21.3-22.4) and pigmentation pattern differences. The N. macropterus species group displayed extensive pigmentation pattern variation, to the extent that five pattern grades could be used to classify them. These pattern grades, while not specific to river systems, showed patterns similar to that which was seen in the molecular analyses and could be linked to lineages with only minor overlap between them. Three lineages of N. multifasciatus were identified, with two occurring in the southern African region, each corresponding to a river system, being the N. multifasciatus “Zambezi” and N. multifasciatus “Okavango” lineages. This species group displayed shallower divergence between lineages than did the N. macropterus group, at 2.5% genetic distance. Genetic analysis inferred a closer relationship between the N. multifasciatus “Zambezi” and N. multifasciatus “Congo” lineages than with the N. multifasciatus “Okavango” lineage. Morphological PCA and DFA analyses indicated morphological divergence of the N. multifasciatus “Congo” lineage, with generally larger proportional measurements than southern African specimens (body width 12.6%SL vs 9.5-9.7%SL; body depth 26.6%SL vs 21.6-21.9%SL; head width 12.0%SL vs 10.0-10.4%SL). PCA, DFA, and measurements show a near complete overlap between the N. multifasciatus “Okavango” and N. multifasciatus “Zambezi” lineages. Pigmentation pattern variation occurred within this group, but none that could be assigned to a particular lineage. The N. machadoi species group in southern Africa consists of five lineages: N. machadoi “Zambezi 1”, N. machadoi “Zambezi 2”, N. machadoi “Kafue 1”, N. machadoi “Kafue 2”, and N. machadoi “Okavango”. This group displayed shallower genetic divergence between lineages than the other southern African Nannocharax species groups (0.4-1.3%). This shallow genetic divergence is paralleled by near complete morphological overlap, with PCA and DFA producing overlapping clusters, and measurements, meristics, and pigmentation pattern metrics consisting of very similar values for the lineages. These results indicate that what is considered to be “N. macropterus” in southern Africa should not be named as such. The N. macropterus “Zambezi” and the N. macropterus “Okavango 1” lineages, are misidentifications of Nannocharax dageti. Other “N. macropterus” from the southern African region possesses fewer circumpeduncular scales than the true N. macropterus as described by Pellegrin (1926), and require taxonomic re-evaluation, each here being recognised as a unique lineage with species status, here named N. macropterus “Okavango 2” and N. macropterus “Kwanza”. In particular, N. macropterus “Kwanza” displays deep genetic divergence as well as morphological dissimilarity with the other southern African “N. macropterus” groups. Nannocharax fasciolaris and N. monardi are here placed as junior synonyms of N. multifasciatus, owing to vast overlaps in measurements and character counts of these species and N. multifasciatus, which is also known to occur within the same geographical distribution, as well as dubious arguments from the original publications in delineating these species from N. multifasciatus. Therefore, there is insufficient evidence indicating the presence of multiple species originating from the Okavango system, where it is here indicated that only a single lineage of banded, adipose fin-bearing Nannocharax occurs, namely N. multifasciatus “Okavango”.
- Full Text:
- Date Issued: 2019
The origin of bedrock depression wetlands in the southern Cape of South Africa: a changing perspective
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
The prediction of, and changes in,medullated fibre levels when processing mohair into top
- Authors: Van Zyl, Andreas Marius
- Date: 2019
- Subjects: Mohair Industry -- South Africa , Textile Fibers Testing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45767 , vital:38962
- Description: The prediction of, and changes in, medullated fibre levels during early stage processing of mohair, from greasy to top, have been studied. Commercial lots, representative of the South African and Basuto mohair clips, covering a wide range of properties, with respect to objectionable medullated (kemp type) fibres, length and fibre diameter, were sampled for testing at three different processing stages, viz. greasy, preparatory gilled sliver, and top. All samples were tested with an Optical Fibre Diameter Analyser (OFDA100) for medullated- and fibre diameter related properties. Various statistical analyses were conducted to determine the most significant correlations and best prediction of changes in medullated fibre levels, during processing. As expected, the medullated fibre levels of the Basuto lots were much higher than those of the Cape lots. Moreover, the inclusion or exclusion of flat fibres, in combination with other medullated fibres, resulted in significant differences in the outcome of some of the statistical analysis. It was found that flat fibre levels were highly correlated with the standard deviation of fibre diameter at all processing stages, and also, the greasy standard deviation of fibre diameter was the best predictor of flat fibre levels in the top. Further, the percentage reduction in flat fibres, from greasy to preparatory gilled sliver, was more than double that of the reduction in flat fibres from preparatory gilled sliver to top. Similarly, the percentage reduction in objectionable medullated (including flat) fibres, from greasy to preparatory gilled sliver, was about 1.7 times more than that of the reduction from preparatory gilled sliver to top.
- Full Text:
- Date Issued: 2019
- Authors: Van Zyl, Andreas Marius
- Date: 2019
- Subjects: Mohair Industry -- South Africa , Textile Fibers Testing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45767 , vital:38962
- Description: The prediction of, and changes in, medullated fibre levels during early stage processing of mohair, from greasy to top, have been studied. Commercial lots, representative of the South African and Basuto mohair clips, covering a wide range of properties, with respect to objectionable medullated (kemp type) fibres, length and fibre diameter, were sampled for testing at three different processing stages, viz. greasy, preparatory gilled sliver, and top. All samples were tested with an Optical Fibre Diameter Analyser (OFDA100) for medullated- and fibre diameter related properties. Various statistical analyses were conducted to determine the most significant correlations and best prediction of changes in medullated fibre levels, during processing. As expected, the medullated fibre levels of the Basuto lots were much higher than those of the Cape lots. Moreover, the inclusion or exclusion of flat fibres, in combination with other medullated fibres, resulted in significant differences in the outcome of some of the statistical analysis. It was found that flat fibre levels were highly correlated with the standard deviation of fibre diameter at all processing stages, and also, the greasy standard deviation of fibre diameter was the best predictor of flat fibre levels in the top. Further, the percentage reduction in flat fibres, from greasy to preparatory gilled sliver, was more than double that of the reduction in flat fibres from preparatory gilled sliver to top. Similarly, the percentage reduction in objectionable medullated (including flat) fibres, from greasy to preparatory gilled sliver, was about 1.7 times more than that of the reduction from preparatory gilled sliver to top.
- Full Text:
- Date Issued: 2019