Decision making for investment in residential real estate
- Authors: James, Matthew Gary Robert
- Date: 2015
- Subjects: Real estate investment -- Decision making Investment analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/10868 , vital:26831
- Description: Investment in residential real estate involves almost all members of the public at some stage of their lives, whether this be one's first home or the purchasing of one‟s first investment property. Understanding how to maximise the return on one's investment is something that can benefit the investor from before the investment is made until after the property has been sold, if it is sold at all. Literature surveys have concluded that there are a number of variables to consider when maximising the return on investment. As residential real estate is not a perfect science, there are guidelines and routes that are more beneficial to the investor depending on the current market, environment and economic standing. A survey was undertaken by members of the public that are involved in residential real estate investment, relative to the maximisation of the return on investment in residential real estate. The salient findings include: Investors in residential real estate spend more than average to extensive time prior, to investment researching the chosen residential real estate property; Investors in residential real estate perform a feasibility study before committing to the development whereas; Investors in residential real estate make use of financial advisors/valuers/estate agents or other investors' knowledge bases in deciding whether to invest in a residential property development; Investors in residential real estate believe that their degree of knowledge about the residential property market and residential property investments are average to very high. Investors in residential real estate somewhat agree that residential real estate investors do not effectively manage their investments. It was recommended that investors make use of help and guidance when investing in residential real estate, perform a feasibility study and ensure that they know their market before investing in a project. It was also noted that location plays a large role when deciding on an investment opportunity worth investing into. By creating awareness and ensuring that all methods and guidelines have been used to maximise the returns that their proposed residential real estate investment, investors can ensure a stronger, healthier cash flow and reap the highest possible benefits from their residential real estate portfolio.
- Full Text:
- Date Issued: 2015
- Authors: James, Matthew Gary Robert
- Date: 2015
- Subjects: Real estate investment -- Decision making Investment analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/10868 , vital:26831
- Description: Investment in residential real estate involves almost all members of the public at some stage of their lives, whether this be one's first home or the purchasing of one‟s first investment property. Understanding how to maximise the return on one's investment is something that can benefit the investor from before the investment is made until after the property has been sold, if it is sold at all. Literature surveys have concluded that there are a number of variables to consider when maximising the return on investment. As residential real estate is not a perfect science, there are guidelines and routes that are more beneficial to the investor depending on the current market, environment and economic standing. A survey was undertaken by members of the public that are involved in residential real estate investment, relative to the maximisation of the return on investment in residential real estate. The salient findings include: Investors in residential real estate spend more than average to extensive time prior, to investment researching the chosen residential real estate property; Investors in residential real estate perform a feasibility study before committing to the development whereas; Investors in residential real estate make use of financial advisors/valuers/estate agents or other investors' knowledge bases in deciding whether to invest in a residential property development; Investors in residential real estate believe that their degree of knowledge about the residential property market and residential property investments are average to very high. Investors in residential real estate somewhat agree that residential real estate investors do not effectively manage their investments. It was recommended that investors make use of help and guidance when investing in residential real estate, perform a feasibility study and ensure that they know their market before investing in a project. It was also noted that location plays a large role when deciding on an investment opportunity worth investing into. By creating awareness and ensuring that all methods and guidelines have been used to maximise the returns that their proposed residential real estate investment, investors can ensure a stronger, healthier cash flow and reap the highest possible benefits from their residential real estate portfolio.
- Full Text:
- Date Issued: 2015
Defect-related photoluminescence of zinc oxide nanorods
- Authors: Mbulanga, Crispin Munyelele
- Date: 2015
- Subjects: Photoluminescence Zinc oxide
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/10318 , vital:26652
- Description: In this dissertation, Zinc oxide (ZnO) nanorods grown by a two-step chemical bath deposition method on Si substrate is characterized. Research was conducted on ZnO nanorods for the understanding of their optical properties at room temperature (RT), with the emphasis on the visible luminescence. To this end, controlled thermal treatments of as-grown ZnO nanorods were conducted under different conditions, such as annealing time and environment, at atmospheric pressure. Results related to the following studies are reported: an investigation of the structure of ZnO nanorods, an analysis of the chemical composition of the surface, an investigation of the surface stoichiometry of the rods, and a study of defect-related photoluminescence of ZnO nanorods upon thermal treatment in different ambients.To achieve this, the samples were investigated by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and room temperature (RT) photoluminescence Spectroscopy (PL). As-grown ZnO nanorods exhibit a hexagonal shape and have the wurtzite structure; they have, respectively, an average length and diameter of ~900 nm and ~50 nm, and most of the rods are perpendicular to the substrate. The main extrinsic species found in as-grown nanostructures are C, H, F, S, and Cl. ToF-SIMS and XPS confirmed the presence of H related-defects, and the oxygen 1 S XPS peak at 531.5 eV is therefore assigned to oxygen bound to H-related defects. Based on stoichiometry studies, it is found that the near surface regions of as-grown ZnO nanorods (2 to 10 monolayers) are rich in Zn. The RT luminescence of as-grown ZnO nanorods exhibits a near band edge emission centered at ~379.5 nm and deep level emission extending from ~450 nm to ~850 nm. When these nanorods are thermally treated at high temperatures (>850 oC), it is found that even though their crystalline quality is preserved, their morphology is significantly affected, regardless of annealing ambient. Furthermore, in the near surface regions of annealed ZnO nanorods it is found that the Zn/O stoichiometric ratios deviate from unity. Specifically, oxygen vacancies form within the first 100 nm from the sample surface. Further from the surface, the material is deficient in Zn. It is deduced from XPS and AES that the ambient affects the activation rate of intrinsic defects. Furthermore, the only extrinsic defects that are affected by thermal treatment are found to be H-related defects. At high annealing temperatures (300 oC to ~700 oC), H-related defects are removed, and this removal process is found to affect significantly the RT luminescence properties of ZnO nanorods. Specifically, hydrogen passivates vacancy-related defects, depending on the thermal treatment. PL spectroscopy is used to follow this passivation effect as a function of annealing temperature, which causes an initial quenching followed by an enhancement of the green and the red luminescence, regardless of the ambient. Finally, the green luminescence that arises following annealing above ~800 oC is assigned to Zn vacancy-related defects, while the red luminescence that dominates the visible band of ZnO nanorods upon annealing between 400 oC and 600 oC is suggested to be due to oxygen vacancy-related defects.
- Full Text:
- Date Issued: 2015
- Authors: Mbulanga, Crispin Munyelele
- Date: 2015
- Subjects: Photoluminescence Zinc oxide
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/10318 , vital:26652
- Description: In this dissertation, Zinc oxide (ZnO) nanorods grown by a two-step chemical bath deposition method on Si substrate is characterized. Research was conducted on ZnO nanorods for the understanding of their optical properties at room temperature (RT), with the emphasis on the visible luminescence. To this end, controlled thermal treatments of as-grown ZnO nanorods were conducted under different conditions, such as annealing time and environment, at atmospheric pressure. Results related to the following studies are reported: an investigation of the structure of ZnO nanorods, an analysis of the chemical composition of the surface, an investigation of the surface stoichiometry of the rods, and a study of defect-related photoluminescence of ZnO nanorods upon thermal treatment in different ambients.To achieve this, the samples were investigated by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and room temperature (RT) photoluminescence Spectroscopy (PL). As-grown ZnO nanorods exhibit a hexagonal shape and have the wurtzite structure; they have, respectively, an average length and diameter of ~900 nm and ~50 nm, and most of the rods are perpendicular to the substrate. The main extrinsic species found in as-grown nanostructures are C, H, F, S, and Cl. ToF-SIMS and XPS confirmed the presence of H related-defects, and the oxygen 1 S XPS peak at 531.5 eV is therefore assigned to oxygen bound to H-related defects. Based on stoichiometry studies, it is found that the near surface regions of as-grown ZnO nanorods (2 to 10 monolayers) are rich in Zn. The RT luminescence of as-grown ZnO nanorods exhibits a near band edge emission centered at ~379.5 nm and deep level emission extending from ~450 nm to ~850 nm. When these nanorods are thermally treated at high temperatures (>850 oC), it is found that even though their crystalline quality is preserved, their morphology is significantly affected, regardless of annealing ambient. Furthermore, in the near surface regions of annealed ZnO nanorods it is found that the Zn/O stoichiometric ratios deviate from unity. Specifically, oxygen vacancies form within the first 100 nm from the sample surface. Further from the surface, the material is deficient in Zn. It is deduced from XPS and AES that the ambient affects the activation rate of intrinsic defects. Furthermore, the only extrinsic defects that are affected by thermal treatment are found to be H-related defects. At high annealing temperatures (300 oC to ~700 oC), H-related defects are removed, and this removal process is found to affect significantly the RT luminescence properties of ZnO nanorods. Specifically, hydrogen passivates vacancy-related defects, depending on the thermal treatment. PL spectroscopy is used to follow this passivation effect as a function of annealing temperature, which causes an initial quenching followed by an enhancement of the green and the red luminescence, regardless of the ambient. Finally, the green luminescence that arises following annealing above ~800 oC is assigned to Zn vacancy-related defects, while the red luminescence that dominates the visible band of ZnO nanorods upon annealing between 400 oC and 600 oC is suggested to be due to oxygen vacancy-related defects.
- Full Text:
- Date Issued: 2015
Design, development and evaluation of novel lead compounds as HIV-1 enzyme inhibitors
- Authors: Sekgota, Khethobole Cassius
- Date: 2015
- Subjects: Enzyme inhibitors , Viruses -- Reproduction , HIV (Viruses)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4546 , http://hdl.handle.net/10962/d1017926
- Description: This project has been concerned with the application of the Baylis-Hillman methodology to the synthesis of medicinally important diketo acid analogues (cinnamate ester-AZT conjugates and 3-hydroxy ester-AZT conjugates) as dual-action HIV-1 IN/RT inhibitors; and on exploratory studies in the preparation of 3-(amidomethyl)-(1H)-2-quinolones as PR inhibitors; and (1H)-2- quinolone-AZT conjugates as dual action IN/RT inhibitors. A series of Baylis-Hillman adducts has been prepared, typically in moderate to excellent yield, by reacting 2-nitrobenzaldehyde with methyl acrylate, ethyl acrylate and methyl vinyl ketone in the presence of 1,4- diazabicyclo[2.2.2]octane (DABCO). Subsequently, various transformations that include conjugate addition of primary and secondary amines to the α,ß-unsaturated moiety to obtain 2- (aminomethyl)-3-hydroxy-3-(2-nitrophenyl)propanoate derivatives, effective SN2´ substitution of the BH ß-hydroxy by a Vilsmeier-Haack in situ-generated chloride to afford Baylis-Hillman allyl chlorides, iron in acetic acid-catalyzed cyclisation to 3-acetoxymethyl-(1H)-2-quinolone derivatives were achieved. Thus, using the Baylis-Hillman methodology, two nuanced classes of diketo acid analogues were constructed. These involved conjugating appropriate propargylamine derivatives with AZT using the „click‟ reaction. In an exploratory study, the quinolone derivative, precisely 3-acetoxymethyl- (1H)-quinol-2-one, was transformed into 3-hydroxymethyl-(1H)-quinol-2-one using potassium carbonate in a mixture of methanol and water (1:1). Following successful hydrolysis, the resulting alcohol was transformed to the corresponding chloride, 3-chloromethyl-(1H)-quinol-2- one, using thionyl chloride. Subsequent nucleophilic substitution afforded 3-(aminomethyl)- (1H)-2-quinolone derivatives which were subsequently transformed to 3-(amidomethyl)-(1H)-2- quinolones; and 3-[(propargylamino)-methyl]-(1H)-quinol-2-one as precursors to quinolone- AZT derivatives. All compounds were characterized by NMR, IR, and where appropriate, high resolution MS
- Full Text:
- Date Issued: 2015
- Authors: Sekgota, Khethobole Cassius
- Date: 2015
- Subjects: Enzyme inhibitors , Viruses -- Reproduction , HIV (Viruses)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4546 , http://hdl.handle.net/10962/d1017926
- Description: This project has been concerned with the application of the Baylis-Hillman methodology to the synthesis of medicinally important diketo acid analogues (cinnamate ester-AZT conjugates and 3-hydroxy ester-AZT conjugates) as dual-action HIV-1 IN/RT inhibitors; and on exploratory studies in the preparation of 3-(amidomethyl)-(1H)-2-quinolones as PR inhibitors; and (1H)-2- quinolone-AZT conjugates as dual action IN/RT inhibitors. A series of Baylis-Hillman adducts has been prepared, typically in moderate to excellent yield, by reacting 2-nitrobenzaldehyde with methyl acrylate, ethyl acrylate and methyl vinyl ketone in the presence of 1,4- diazabicyclo[2.2.2]octane (DABCO). Subsequently, various transformations that include conjugate addition of primary and secondary amines to the α,ß-unsaturated moiety to obtain 2- (aminomethyl)-3-hydroxy-3-(2-nitrophenyl)propanoate derivatives, effective SN2´ substitution of the BH ß-hydroxy by a Vilsmeier-Haack in situ-generated chloride to afford Baylis-Hillman allyl chlorides, iron in acetic acid-catalyzed cyclisation to 3-acetoxymethyl-(1H)-2-quinolone derivatives were achieved. Thus, using the Baylis-Hillman methodology, two nuanced classes of diketo acid analogues were constructed. These involved conjugating appropriate propargylamine derivatives with AZT using the „click‟ reaction. In an exploratory study, the quinolone derivative, precisely 3-acetoxymethyl- (1H)-quinol-2-one, was transformed into 3-hydroxymethyl-(1H)-quinol-2-one using potassium carbonate in a mixture of methanol and water (1:1). Following successful hydrolysis, the resulting alcohol was transformed to the corresponding chloride, 3-chloromethyl-(1H)-quinol-2- one, using thionyl chloride. Subsequent nucleophilic substitution afforded 3-(aminomethyl)- (1H)-2-quinolone derivatives which were subsequently transformed to 3-(amidomethyl)-(1H)-2- quinolones; and 3-[(propargylamino)-methyl]-(1H)-quinol-2-one as precursors to quinolone- AZT derivatives. All compounds were characterized by NMR, IR, and where appropriate, high resolution MS
- Full Text:
- Date Issued: 2015
Determination and validation of medicinal plants used by farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa
- Authors: Sanhokwe, Marcia
- Date: 2015
- Subjects: Medicinal plants -- South Africa -- Eastern Cape Goats -- Parasites -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2249 , vital:27718
- Description: The broad objective of the study was to determine and validate medicinal plants used by resource-limited farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa. A survey was conducted among 50 farmers and three herbalists to determine medicinal plants used to control parasites in goats. The survey revealed nine plant species belonging to eight families that were used. Among the identified plant species, Aloe ferox, Acokanthera oppositifolia and Elephantorrhiza elephantina were the plants having the highest Fidelity Level for their use, each scored 100.00 percent, followed by Albuca setosa (83.33 percent). These plants were then selected for validation studies. Gas-Chromatography-Mass-Spectrometry (GC-MS) revealed 7, 33, 26 and 32 bioactive phytochemicals in A. ferox, E. elephantina, A. oppositifolia and A. setosa, respectively. Terpenes and fatty acids were present, oxygenated terpenes being the most abundant hydrocarbons present in all the four plant species. The effect of acetone, methanol and ethanol extracts of leaves of Aloe ferox and Acokanthera oppositifolia on tick repellency and acaricidal activity were investigated on blood engorged Ambylomma hebraeum and Rhipicephalus decoloratus ticks at concentration 15, 30 and 50 percent. The 30 and 50 percent acetone extract of A. ferox and Dazzel dip had the highest acaricidal properties of 100 percent. The 50 percent methanol extract of A. oppositifolia and 50 percent acetone extract of A. ferox had the highest repellency activity of 89 percent and 85.33 percent, respectively. Results from this study revealed that the efficacy of medicinal plants used by farmers to control ticks vary with the type of solvent used for extracting the bioactive compounds. Furthermore, it revealed that Aloe ferox and A. opppositifolia plant extracts possess repellent and acaricidal activities. In a study to investigate the anthelminthic effect of crude extracts of Elephantorrhiza elephantina and Albuca setosa plants, significant anthelminthic effect on nematodes was observed in both plants. In this study, all E. elephantina and A. setosa extracts caused paralysis and mortality. Methanol was the most effective solvent in extracting bioactive compounds and methanol extract showed the best anthelminthic effects among the crude extracts investigated in both plants. The least time taken for the worms to be paralysed was 8.33 mins and 14.33mins in 100mg/ml methanol extracts of E. elephantina and A. setosa, resepectively. Methanol extract of E. elephantina and A. setosa (100mg/ml) had the highest anthelminthic activity and mortality was recorded after 18mins and 20mins, respectively. Results from this study revealed that these two plants possess anthelminthic activities. The study revealed that resource-limited farmers use medicinal plants to control internal and external parasites in goats. Gas-Chromatography-Mass-Spectrometry analysis showed that these plants contain bioactive compounds that have a potential in controlling parasites. Validation studies showed that A. ferox and A. oppositifolia possess repellent and acaricidal activities whereas A. setosa and E. elephantina possess anthelminthic activities.
- Full Text:
- Date Issued: 2015
- Authors: Sanhokwe, Marcia
- Date: 2015
- Subjects: Medicinal plants -- South Africa -- Eastern Cape Goats -- Parasites -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2249 , vital:27718
- Description: The broad objective of the study was to determine and validate medicinal plants used by resource-limited farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa. A survey was conducted among 50 farmers and three herbalists to determine medicinal plants used to control parasites in goats. The survey revealed nine plant species belonging to eight families that were used. Among the identified plant species, Aloe ferox, Acokanthera oppositifolia and Elephantorrhiza elephantina were the plants having the highest Fidelity Level for their use, each scored 100.00 percent, followed by Albuca setosa (83.33 percent). These plants were then selected for validation studies. Gas-Chromatography-Mass-Spectrometry (GC-MS) revealed 7, 33, 26 and 32 bioactive phytochemicals in A. ferox, E. elephantina, A. oppositifolia and A. setosa, respectively. Terpenes and fatty acids were present, oxygenated terpenes being the most abundant hydrocarbons present in all the four plant species. The effect of acetone, methanol and ethanol extracts of leaves of Aloe ferox and Acokanthera oppositifolia on tick repellency and acaricidal activity were investigated on blood engorged Ambylomma hebraeum and Rhipicephalus decoloratus ticks at concentration 15, 30 and 50 percent. The 30 and 50 percent acetone extract of A. ferox and Dazzel dip had the highest acaricidal properties of 100 percent. The 50 percent methanol extract of A. oppositifolia and 50 percent acetone extract of A. ferox had the highest repellency activity of 89 percent and 85.33 percent, respectively. Results from this study revealed that the efficacy of medicinal plants used by farmers to control ticks vary with the type of solvent used for extracting the bioactive compounds. Furthermore, it revealed that Aloe ferox and A. opppositifolia plant extracts possess repellent and acaricidal activities. In a study to investigate the anthelminthic effect of crude extracts of Elephantorrhiza elephantina and Albuca setosa plants, significant anthelminthic effect on nematodes was observed in both plants. In this study, all E. elephantina and A. setosa extracts caused paralysis and mortality. Methanol was the most effective solvent in extracting bioactive compounds and methanol extract showed the best anthelminthic effects among the crude extracts investigated in both plants. The least time taken for the worms to be paralysed was 8.33 mins and 14.33mins in 100mg/ml methanol extracts of E. elephantina and A. setosa, resepectively. Methanol extract of E. elephantina and A. setosa (100mg/ml) had the highest anthelminthic activity and mortality was recorded after 18mins and 20mins, respectively. Results from this study revealed that these two plants possess anthelminthic activities. The study revealed that resource-limited farmers use medicinal plants to control internal and external parasites in goats. Gas-Chromatography-Mass-Spectrometry analysis showed that these plants contain bioactive compounds that have a potential in controlling parasites. Validation studies showed that A. ferox and A. oppositifolia possess repellent and acaricidal activities whereas A. setosa and E. elephantina possess anthelminthic activities.
- Full Text:
- Date Issued: 2015
Determination of the effects of sunlight and UV irradiation on the structure, viability and reapplication frequency of the biopesticide cryptophlebia leucotreta granulovirus in the protection against false codling moth infestation of citrus crops
- Authors: Mwanza, Patrick
- Date: 2015
- Subjects: Cryptophlebia leucotreta -- Effect of ultraviolet radiation on , Natural pesticides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/6346 , vital:21075
- Description: Cryptophlebia leucotreta granulovirus (CrleGV-SA) is a baculovirus specifically pathogenic to the citrus pest false codling moth, Thaumatotibia leucotreta. CrleGV- SA is formulated as a commercial biopesticide, Cryptogran® (River Bioscience, South Africa). The virus has a stable, proteinaceous crystalline occlusion body (OB) that protects the nucleocapsid. The major limitation to the use of baculoviruses is their susceptibility to the ultraviolet (UV) component of sunlight, which rapidly and greatly reduces their efficacy as biopesticides. The UVA and UVB components are the most destructive to biological organisms. To date no publication has reported the effect of UV on the structure and virulence of CrleGV, or the effectiveness of the OB as a UV protectant. In this study the effect of UV irradiation on the structure and infectivity of pure CrleGV-SA and Cryptogran® was investigated using scanning electron microscopy (SEM), Raman spectroscopy, qPCR, and bioassays. The project included laboratory and field studies. In the laboratory, CrleGV-SA and Cryptogran® were exposed to either UVA or UVB for periods of 24 hours to 7 days before analysis. In the field, Cryptogran® was applied to trees in a citrus orchard with young fruit. The fruit were collected from 24 hours to 28 days after application and bioassays conducted to assess the effect of sunlight over time on virus structure and efficacy when applied to the northern or southern sides of the trees. No surface morphological changes to the virus were detected using SEM. However, small compositional changes were detected by Raman spectroscopy. qPCR and bioassays demonstrated that UV irradiation damaged the viral DNA, greatly reducing the infectivity of pure CrleGV-SA and Cryptogran®. Exposure to UVB reduced the virulence of the virus more than UVA. The field studies revealed that the activity of CrleGV-SA decreased more on the northern side of the trees than on the southern side.
- Full Text:
- Date Issued: 2015
- Authors: Mwanza, Patrick
- Date: 2015
- Subjects: Cryptophlebia leucotreta -- Effect of ultraviolet radiation on , Natural pesticides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/6346 , vital:21075
- Description: Cryptophlebia leucotreta granulovirus (CrleGV-SA) is a baculovirus specifically pathogenic to the citrus pest false codling moth, Thaumatotibia leucotreta. CrleGV- SA is formulated as a commercial biopesticide, Cryptogran® (River Bioscience, South Africa). The virus has a stable, proteinaceous crystalline occlusion body (OB) that protects the nucleocapsid. The major limitation to the use of baculoviruses is their susceptibility to the ultraviolet (UV) component of sunlight, which rapidly and greatly reduces their efficacy as biopesticides. The UVA and UVB components are the most destructive to biological organisms. To date no publication has reported the effect of UV on the structure and virulence of CrleGV, or the effectiveness of the OB as a UV protectant. In this study the effect of UV irradiation on the structure and infectivity of pure CrleGV-SA and Cryptogran® was investigated using scanning electron microscopy (SEM), Raman spectroscopy, qPCR, and bioassays. The project included laboratory and field studies. In the laboratory, CrleGV-SA and Cryptogran® were exposed to either UVA or UVB for periods of 24 hours to 7 days before analysis. In the field, Cryptogran® was applied to trees in a citrus orchard with young fruit. The fruit were collected from 24 hours to 28 days after application and bioassays conducted to assess the effect of sunlight over time on virus structure and efficacy when applied to the northern or southern sides of the trees. No surface morphological changes to the virus were detected using SEM. However, small compositional changes were detected by Raman spectroscopy. qPCR and bioassays demonstrated that UV irradiation damaged the viral DNA, greatly reducing the infectivity of pure CrleGV-SA and Cryptogran®. Exposure to UVB reduced the virulence of the virus more than UVA. The field studies revealed that the activity of CrleGV-SA decreased more on the northern side of the trees than on the southern side.
- Full Text:
- Date Issued: 2015
Developing a cross platform IMS client using the JAIN SIP applet phone
- Authors: Muswera, Walter Tawanda
- Date: 2015
- Subjects: Internet Protocol multimedia subsystem , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4712 , http://hdl.handle.net/10962/d1017934
- Description: Since the introduction of the IP Multimedia Subsystem (IMS) by the Third Generation Partnership Project (3GPP) in 2002, a lot of research has been conducted aimed at designing and implementing IMS capable clients and network elements. Though considerable work has been done in the development of IMS clients, there is no single, free and open source IMS client that provides researchers with all the required functionality needed to test the applications they are developing. For example, several open and closed source SIP/IMS clients are used within the Rhodes University Conver- gence Research Group (RUCRG) to test applications under development, as a result of the fact that the various SIP/IMS clients support different subsets of SIP/IMS features. The lack of a single client and the subsequent use of various clients comes with several problems. Researchers have to know how to deploy, configure, use and at times adapt the various clients to suit their needs. This can be very time consuming and, in fact, contradicts the IMS philosophy (the IMS was proposed to support rapid service creation). This thesis outlines the development of a Java-based, IMS compliant client called RUCRG IMS client, that uses the JAIN SIP Applet Phone (JSAP) as its foundation. JSAP, which originally offered only basic voice calling and instant messaging (IM) capabilities, was modified to be IMS compliant and support video calls, IM and presence using XML Configuration Access Protocol (XCAP).
- Full Text:
- Date Issued: 2015
- Authors: Muswera, Walter Tawanda
- Date: 2015
- Subjects: Internet Protocol multimedia subsystem , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4712 , http://hdl.handle.net/10962/d1017934
- Description: Since the introduction of the IP Multimedia Subsystem (IMS) by the Third Generation Partnership Project (3GPP) in 2002, a lot of research has been conducted aimed at designing and implementing IMS capable clients and network elements. Though considerable work has been done in the development of IMS clients, there is no single, free and open source IMS client that provides researchers with all the required functionality needed to test the applications they are developing. For example, several open and closed source SIP/IMS clients are used within the Rhodes University Conver- gence Research Group (RUCRG) to test applications under development, as a result of the fact that the various SIP/IMS clients support different subsets of SIP/IMS features. The lack of a single client and the subsequent use of various clients comes with several problems. Researchers have to know how to deploy, configure, use and at times adapt the various clients to suit their needs. This can be very time consuming and, in fact, contradicts the IMS philosophy (the IMS was proposed to support rapid service creation). This thesis outlines the development of a Java-based, IMS compliant client called RUCRG IMS client, that uses the JAIN SIP Applet Phone (JSAP) as its foundation. JSAP, which originally offered only basic voice calling and instant messaging (IM) capabilities, was modified to be IMS compliant and support video calls, IM and presence using XML Configuration Access Protocol (XCAP).
- Full Text:
- Date Issued: 2015
Developing a GIS based method for school site identification in the rural Eastern Cape
- Authors: Swart, Conrad Dirk
- Date: 2015
- Subjects: Geographic information systems -- South Africa -- Eastern Cape , School sites -- South Africa -- Eastern Cape , School sites -- South Africa -- Eastern Cape -- Planning , Rural schools -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4891 , http://hdl.handle.net/10962/d1018939
- Description: Historically, South Africa has not had equal education in terms of funding, curriculum or physical resources and structures. These issues are still present in contemporary South Africa and none more so than the issues surrounding “mud schools”. Recently the Department of Basic Education (DBE) implemented a plan to eradicate inappropriate school structures using the Accelerated Schools Infrastructure Delivery Initiative program (ASIDI). Questions around effective placement of schools are now being asked. Using interviews and analysis of literature, this research developed criteria needed to determine how rural school sites are selected. Geographical Information Systems (GIS) was used to determine if current sites are in the most appropriate areas. The results of the research included a unique set of Eastern Cape criteria as well as an analysis of the current site selection methods used by the DBE. It also revealed that most of the schools are being constructed in acceptable areas. The main result that emerged from the research was that schools will be placed in areas where they are needed. Developing site selection criteria is still needed as South Africa seeks to reduce the education gap between rich and poor schools.
- Full Text:
- Date Issued: 2015
- Authors: Swart, Conrad Dirk
- Date: 2015
- Subjects: Geographic information systems -- South Africa -- Eastern Cape , School sites -- South Africa -- Eastern Cape , School sites -- South Africa -- Eastern Cape -- Planning , Rural schools -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4891 , http://hdl.handle.net/10962/d1018939
- Description: Historically, South Africa has not had equal education in terms of funding, curriculum or physical resources and structures. These issues are still present in contemporary South Africa and none more so than the issues surrounding “mud schools”. Recently the Department of Basic Education (DBE) implemented a plan to eradicate inappropriate school structures using the Accelerated Schools Infrastructure Delivery Initiative program (ASIDI). Questions around effective placement of schools are now being asked. Using interviews and analysis of literature, this research developed criteria needed to determine how rural school sites are selected. Geographical Information Systems (GIS) was used to determine if current sites are in the most appropriate areas. The results of the research included a unique set of Eastern Cape criteria as well as an analysis of the current site selection methods used by the DBE. It also revealed that most of the schools are being constructed in acceptable areas. The main result that emerged from the research was that schools will be placed in areas where they are needed. Developing site selection criteria is still needed as South Africa seeks to reduce the education gap between rich and poor schools.
- Full Text:
- Date Issued: 2015
Developing high-fidelity mental models of programming concepts using manipulatives and interactive metaphors
- Authors: Funcke, Matthew
- Date: 2015
- Subjects: Computer programming -- Study and teaching (Higher) , Computer programmers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4707 , http://hdl.handle.net/10962/d1017929
- Description: It is well established that both learning and teaching programming are difficult tasks. Difficulties often occur due to weak mental models and common misconceptions. This study proposes a method of teaching programming that both encourages high-fidelity mental models and attempts to minimise misconceptions in novice programmers, through the use of metaphors and manipulatives. The elements in ActionWorld with which the students interact are realizations of metaphors. By simple example, a variable has a metaphorical representation as a labelled box that can hold a value. The dissertation develops a set of metaphors which have several core requirements: metaphors should avoid causing misconceptions, they need to be high-fidelity so as to avoid failing when used with a new concept, students must be able to relate to them, and finally, they should be usable across multiple educational media. The learning style that ActionWorld supports is one which requires active participation from the student - the system acts as a foundation upon which students are encouraged to build their mental models. This teaching style is achieved by placing the student in the role of code interpreter, the code they need to interpret will not advance until they have demonstrated its meaning via use of the aforementioned metaphors. ActionWorld was developed using an iterative developmental process that consistently improved upon various aspects of the project through a continual evaluation-enhancement cycle. The primary outputs of this project include a unified set of high-fidelity metaphors, a virtual-machine API for use in similar future projects, and two metaphor-testing games. All of the aforementioned deliverables were tested using multiple quality-evaluation criteria, the results of which were consistently positive. ActionWorld and its constituent components contribute to the wide assortment of methods one might use to teach novice programmers.
- Full Text:
- Date Issued: 2015
- Authors: Funcke, Matthew
- Date: 2015
- Subjects: Computer programming -- Study and teaching (Higher) , Computer programmers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4707 , http://hdl.handle.net/10962/d1017929
- Description: It is well established that both learning and teaching programming are difficult tasks. Difficulties often occur due to weak mental models and common misconceptions. This study proposes a method of teaching programming that both encourages high-fidelity mental models and attempts to minimise misconceptions in novice programmers, through the use of metaphors and manipulatives. The elements in ActionWorld with which the students interact are realizations of metaphors. By simple example, a variable has a metaphorical representation as a labelled box that can hold a value. The dissertation develops a set of metaphors which have several core requirements: metaphors should avoid causing misconceptions, they need to be high-fidelity so as to avoid failing when used with a new concept, students must be able to relate to them, and finally, they should be usable across multiple educational media. The learning style that ActionWorld supports is one which requires active participation from the student - the system acts as a foundation upon which students are encouraged to build their mental models. This teaching style is achieved by placing the student in the role of code interpreter, the code they need to interpret will not advance until they have demonstrated its meaning via use of the aforementioned metaphors. ActionWorld was developed using an iterative developmental process that consistently improved upon various aspects of the project through a continual evaluation-enhancement cycle. The primary outputs of this project include a unified set of high-fidelity metaphors, a virtual-machine API for use in similar future projects, and two metaphor-testing games. All of the aforementioned deliverables were tested using multiple quality-evaluation criteria, the results of which were consistently positive. ActionWorld and its constituent components contribute to the wide assortment of methods one might use to teach novice programmers.
- Full Text:
- Date Issued: 2015
DNA-based identification of forensically significant beetles from Southern Africa
- Authors: Collett, Isabel Judith
- Date: 2015
- Subjects: Carrion insects , Forensic entomology , Cleridae , Dermestidae , Silphidae , Staphylinidae , Scarabaeidae , Histeridae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5923 , http://hdl.handle.net/10962/d1017801
- Description: Necrophilous insects, if correctly identified, can provide useful forensic information. Research in this area has focussed on flies and beetles remain comparatively under-studied, partly because some adult carrion beetles are difficult to identify morphologically, as are their juvenile stages, often requiring specialist expertise in both cases. Molecular taxonomy has been proposed as a solution to these problems. DNA “barcodes" are short fragments of mitochondrial cytochrome oxidase I (COI) DNA that are anticipated to delineate species. This approach is becoming increasingly popular, but has been met with varying enthusiasm from taxonomists. This thesis examines their use in identifying forensically significant beetles.The DNA barcodes of 234 specimens of 25 forensically significant southern African beetle species from seven families (Cleridae, Dermestidae, Silphidae, Staphylinidae, Scarabaeidae, Trogidae and Histeridae) were obtained. Thirty-three initial barcode amplification failures were overcome by using primers other than the standard Folmer pair, undermining the barcode concept’s hope of universal primers that would allow even non-specialists to produce barcodes. Another 150 specimens (64%) entirely failed to yield barcodes, including 18 fresh specimens of three species of Trogidae, implying another lack of universality of the barcoding protocol. The majority of the beetles clustered with confamilials on neighbour-joining and maximum likelihood trees, but 1.3% of the barcodes failed to cluster with their respective families, raising questions concerning the associating power of barcodes. The identification tools of the GenBank and BOLD on-line DNA sequence databases identified 21% of the specimens to the species level, 6% of them correctly. There was evidence of a paralogous sequence in the Cleridae that, while supporting identification now that it has been associated with a morphological identification, would hamper attempts at identification by clustering or phylogenetic analysis.Distance and haplotype network analyses of the barcodes of six widespread species showed that they are not geographically structured. Barcodes are thus unlikely to be indicators of the region of origin of a species and will not determine whether a corpse has been relocated after death. To assess whether a different mitochondrial DNA fragment might address (some of) these problems, a 2.2 kb fragment extending from the 5’ end of the COI gene to the 3’ end of the Cytochrome Oxidase II (COII) gene was analysed for nine species. It was found that, for Dermestidae, Scarabaeidae and Histeridae, higher degrees of diversity occurred downstreamof the barcode region, but the region of highest diversity in the Cleridae was in the barcode region. Thus, finding a more reliable fragment along the COI-COII region for each family may make robust and guaranteed DNA-based identification of these beetles more likely. The possibility of a forensic specimen being incorrectly or not identified based on its barcode alone exists in about 40% of cases, even with the new barcodes reported here. Forensic science sets a very high bar in assessing the performance of its techniques, and it is concluded that barcodes currently have unsettling failure rates as court-worthy evidence.
- Full Text:
- Date Issued: 2015
- Authors: Collett, Isabel Judith
- Date: 2015
- Subjects: Carrion insects , Forensic entomology , Cleridae , Dermestidae , Silphidae , Staphylinidae , Scarabaeidae , Histeridae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5923 , http://hdl.handle.net/10962/d1017801
- Description: Necrophilous insects, if correctly identified, can provide useful forensic information. Research in this area has focussed on flies and beetles remain comparatively under-studied, partly because some adult carrion beetles are difficult to identify morphologically, as are their juvenile stages, often requiring specialist expertise in both cases. Molecular taxonomy has been proposed as a solution to these problems. DNA “barcodes" are short fragments of mitochondrial cytochrome oxidase I (COI) DNA that are anticipated to delineate species. This approach is becoming increasingly popular, but has been met with varying enthusiasm from taxonomists. This thesis examines their use in identifying forensically significant beetles.The DNA barcodes of 234 specimens of 25 forensically significant southern African beetle species from seven families (Cleridae, Dermestidae, Silphidae, Staphylinidae, Scarabaeidae, Trogidae and Histeridae) were obtained. Thirty-three initial barcode amplification failures were overcome by using primers other than the standard Folmer pair, undermining the barcode concept’s hope of universal primers that would allow even non-specialists to produce barcodes. Another 150 specimens (64%) entirely failed to yield barcodes, including 18 fresh specimens of three species of Trogidae, implying another lack of universality of the barcoding protocol. The majority of the beetles clustered with confamilials on neighbour-joining and maximum likelihood trees, but 1.3% of the barcodes failed to cluster with their respective families, raising questions concerning the associating power of barcodes. The identification tools of the GenBank and BOLD on-line DNA sequence databases identified 21% of the specimens to the species level, 6% of them correctly. There was evidence of a paralogous sequence in the Cleridae that, while supporting identification now that it has been associated with a morphological identification, would hamper attempts at identification by clustering or phylogenetic analysis.Distance and haplotype network analyses of the barcodes of six widespread species showed that they are not geographically structured. Barcodes are thus unlikely to be indicators of the region of origin of a species and will not determine whether a corpse has been relocated after death. To assess whether a different mitochondrial DNA fragment might address (some of) these problems, a 2.2 kb fragment extending from the 5’ end of the COI gene to the 3’ end of the Cytochrome Oxidase II (COII) gene was analysed for nine species. It was found that, for Dermestidae, Scarabaeidae and Histeridae, higher degrees of diversity occurred downstreamof the barcode region, but the region of highest diversity in the Cleridae was in the barcode region. Thus, finding a more reliable fragment along the COI-COII region for each family may make robust and guaranteed DNA-based identification of these beetles more likely. The possibility of a forensic specimen being incorrectly or not identified based on its barcode alone exists in about 40% of cases, even with the new barcodes reported here. Forensic science sets a very high bar in assessing the performance of its techniques, and it is concluded that barcodes currently have unsettling failure rates as court-worthy evidence.
- Full Text:
- Date Issued: 2015
Drought responses of selected C₄ photosynthetic NADP-Me and NAD-Me Panicoideae and Aristidoideae grasses
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
Ecological risk assessment of fisheries on sea turtles in the South Western Indian Ocean
- Authors: Mellet, Bernice
- Date: 2015
- Subjects: Sea turtles -- Indian Ocean Fisheries -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/9957 , vital:26636
- Description: The SWIO is an area of great biodiversity and included in the diverse species that occupy the region are five species of sea turtles that include green turtles, hawksbills, leatherbacks, loggerheads and olive ridleys. Despite considerable conservation efforts at sea turtle rookeries in the South Western Indian Ocean, only green and loggerhead turtle populations have shown an increase in population size in recent years (<10 years), whereas leatherbacks remained stable and hawksbills and olive ridleys declined. This begs the question if fisheries (or other offshore pressures) are responsible for slowing the recovery of these populations in the region, and if so, which specific fisheries are responsible for this trend? Several offshore (mostly industrial) and coastal (mostly artisanal) fisheries overlap with sea turtle distribution at sea. Industrial fisheries that are globally known to have a demonstrable impact on sea turtle populations are longline and to a lesser extent purse seine fisheries, whilst prawn trawl, gillnet and beach seine fisheries are coastal fisheries with a known negative impact on sea turtle populations. Holistic conservation strategies should be developed that include both land and sea protection for sea turtle species. It is thus necessary to identify and manage offshore threats including fisheries activities, particularly those fisheries that are showing the highest risk to sea turtle populations. This prompted an investigation into the bycatch rates and mortality of all sea turtle species that occur in the SWIO region in several offshore and coastal fisheries including both industrial (longline, purse seine and prawn trawl) and artisanal (including gillnet and beach seine) fisheries. The specific aims were (i) to identify and quantify the interactions (and if possible mortality) of sea turtle species in fisheries and (ii) to identify vulnerable species/populations to fishing operations using a semi-quantitative Ecological Risk Assessment (ERA) in the form of a Productivity-Susceptibility Analysis (PSA). Published information, online databases and technical reports were used as data sources to establish a database containing essential information regarding fishing effort and sea turtle bycatch in the region. The existing information was used to map fisheries extent and effort within the region, and to perform bycatch calculations. Interactions and mortality rates for sea turtles in five fisheries were quantified using bycatch rates from regional studies. Between 2000 – 2011, industrial longline and purse seine fisheries captured sea turtles at a rate of 4 388 indiv.y-1, with the mortality rate being 189 indiv.y-1. The bulk of these interactions were in the longline industry that captured 4 129 ± 1 376 indiv.y-1, with a corresponding mortality rate of 167 ± 53 indiv.y-1. The most commonly caught species (in longlines) were loggerheads and leatherback turtles, but the greatest impact is expected to be on the leatherback population due to the high interaction rate relative to population size. The bycatch (259 ± 34 indiv.y-1) and mortality (20 ± 2 indiv.y-1) rates of sea turtles in the purse seine fishery was considerably lower than the longline fishery. The purse seine fishery thus does not seem to have a significant impact on sea turtle populations in the SWIO. The impact of all forms of fish aggregation devices were excluded from the analysis as the impacts of these are poorly documented. Coastal prawn trawl, gillnet and beach seine fisheries captured an estimate of between 50 164 - 52 370 indiv.y-1 from 2000-2011. The highest bycatch rate was estimated for gillnet fisheries (40 264 indiv.y-1) followed by beach seine fisheries (9 171 indiv.y-1) and prawn trawl fisheries (at 1089 – 2795 indiv.y-1). The gillnet fishery could be responsible for slowing the recovery rate of green turtle and leatherback populations in the SWIO due to the high capture rates in this fishery compared to the population sizes of the species. Beach seine and prawn trawl fisheries are not expected to be hamper the recovery rate of any of the populations in the SWIO due to the low levels of interactions and low mortality rates compared to the population sizes. There are however very few data available regarding the bycatch of sea turtle species within these fisheries, highlighting the need for further research regarding this. A productivity-Susceptibility Analysis (PSA) was used to evaluate the relative vulnerability of species to fisheries, and is frequently applied in data poor situations. Limited data on sea turtle life history characteristics and population dynamics of species in the SWIO prompted the use of a PSA to determine the species most vulnerable to fisheries in the region. Results of the PSA indicated that gillnet fisheries poses the largest fishery-related threat to sea turtle populations, specifically the green and leatherback populations. The longline fishery that poses a particular threat to the leatherback population in the SWIO is also a particular concern. A cumulative impact assessment (combining fisheries and other threats) indicated that the SWIO leatherback population is extremely vulnerable to the combination of threats that influence this population in the SWIO. Even though individual fisheries may pose a small threat, the cumulative impacts of the fisheries can lead to severe impacts on populations such as slowing the recovery rate of populations. There are however significant data gaps that require attention in order to fully assess the impact of these fisheries on sea turtle populations. Despite the fact that fisheries are not implicated as a mayor reason for the decline in the hawksbill and olive ridley populations in the region, these two species are in decline indicating that there are other factors responsible for the decline not yet identified. It however remains imperative to reduce the mortality from all sources to ensure the continued viability of sea turtle populations in the region.
- Full Text:
- Date Issued: 2015
- Authors: Mellet, Bernice
- Date: 2015
- Subjects: Sea turtles -- Indian Ocean Fisheries -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/9957 , vital:26636
- Description: The SWIO is an area of great biodiversity and included in the diverse species that occupy the region are five species of sea turtles that include green turtles, hawksbills, leatherbacks, loggerheads and olive ridleys. Despite considerable conservation efforts at sea turtle rookeries in the South Western Indian Ocean, only green and loggerhead turtle populations have shown an increase in population size in recent years (<10 years), whereas leatherbacks remained stable and hawksbills and olive ridleys declined. This begs the question if fisheries (or other offshore pressures) are responsible for slowing the recovery of these populations in the region, and if so, which specific fisheries are responsible for this trend? Several offshore (mostly industrial) and coastal (mostly artisanal) fisheries overlap with sea turtle distribution at sea. Industrial fisheries that are globally known to have a demonstrable impact on sea turtle populations are longline and to a lesser extent purse seine fisheries, whilst prawn trawl, gillnet and beach seine fisheries are coastal fisheries with a known negative impact on sea turtle populations. Holistic conservation strategies should be developed that include both land and sea protection for sea turtle species. It is thus necessary to identify and manage offshore threats including fisheries activities, particularly those fisheries that are showing the highest risk to sea turtle populations. This prompted an investigation into the bycatch rates and mortality of all sea turtle species that occur in the SWIO region in several offshore and coastal fisheries including both industrial (longline, purse seine and prawn trawl) and artisanal (including gillnet and beach seine) fisheries. The specific aims were (i) to identify and quantify the interactions (and if possible mortality) of sea turtle species in fisheries and (ii) to identify vulnerable species/populations to fishing operations using a semi-quantitative Ecological Risk Assessment (ERA) in the form of a Productivity-Susceptibility Analysis (PSA). Published information, online databases and technical reports were used as data sources to establish a database containing essential information regarding fishing effort and sea turtle bycatch in the region. The existing information was used to map fisheries extent and effort within the region, and to perform bycatch calculations. Interactions and mortality rates for sea turtles in five fisheries were quantified using bycatch rates from regional studies. Between 2000 – 2011, industrial longline and purse seine fisheries captured sea turtles at a rate of 4 388 indiv.y-1, with the mortality rate being 189 indiv.y-1. The bulk of these interactions were in the longline industry that captured 4 129 ± 1 376 indiv.y-1, with a corresponding mortality rate of 167 ± 53 indiv.y-1. The most commonly caught species (in longlines) were loggerheads and leatherback turtles, but the greatest impact is expected to be on the leatherback population due to the high interaction rate relative to population size. The bycatch (259 ± 34 indiv.y-1) and mortality (20 ± 2 indiv.y-1) rates of sea turtles in the purse seine fishery was considerably lower than the longline fishery. The purse seine fishery thus does not seem to have a significant impact on sea turtle populations in the SWIO. The impact of all forms of fish aggregation devices were excluded from the analysis as the impacts of these are poorly documented. Coastal prawn trawl, gillnet and beach seine fisheries captured an estimate of between 50 164 - 52 370 indiv.y-1 from 2000-2011. The highest bycatch rate was estimated for gillnet fisheries (40 264 indiv.y-1) followed by beach seine fisheries (9 171 indiv.y-1) and prawn trawl fisheries (at 1089 – 2795 indiv.y-1). The gillnet fishery could be responsible for slowing the recovery rate of green turtle and leatherback populations in the SWIO due to the high capture rates in this fishery compared to the population sizes of the species. Beach seine and prawn trawl fisheries are not expected to be hamper the recovery rate of any of the populations in the SWIO due to the low levels of interactions and low mortality rates compared to the population sizes. There are however very few data available regarding the bycatch of sea turtle species within these fisheries, highlighting the need for further research regarding this. A productivity-Susceptibility Analysis (PSA) was used to evaluate the relative vulnerability of species to fisheries, and is frequently applied in data poor situations. Limited data on sea turtle life history characteristics and population dynamics of species in the SWIO prompted the use of a PSA to determine the species most vulnerable to fisheries in the region. Results of the PSA indicated that gillnet fisheries poses the largest fishery-related threat to sea turtle populations, specifically the green and leatherback populations. The longline fishery that poses a particular threat to the leatherback population in the SWIO is also a particular concern. A cumulative impact assessment (combining fisheries and other threats) indicated that the SWIO leatherback population is extremely vulnerable to the combination of threats that influence this population in the SWIO. Even though individual fisheries may pose a small threat, the cumulative impacts of the fisheries can lead to severe impacts on populations such as slowing the recovery rate of populations. There are however significant data gaps that require attention in order to fully assess the impact of these fisheries on sea turtle populations. Despite the fact that fisheries are not implicated as a mayor reason for the decline in the hawksbill and olive ridley populations in the region, these two species are in decline indicating that there are other factors responsible for the decline not yet identified. It however remains imperative to reduce the mortality from all sources to ensure the continued viability of sea turtle populations in the region.
- Full Text:
- Date Issued: 2015
Effect of Tenebrio molitor larvae as a protein source on growth performance, carcass yield and meat quality of broiler chickens
- Authors: Mngqi, Sinethemba Census
- Date: 2015
- Subjects: Broilers (Chickens) Chickens -- Feeding and feeds Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2622 , vital:27944
- Description: This study was conducted to assess the effect of including Tenebrio molitor larvae (T. molitor L) as a protein source in different diets on broiler performance, carcass characteristics and meat quality. A total of 144 day-old Cobb-500 chicks were randomly allocated into three treatment groups, each was allocated 16 birds and reared in 9 identical pens. Experimental diets used were as follows: T1 Control (no T. molitor L inclusion); T2 and T3 contained levels of T. molitor L at 5 percent and 10 percent of dry matter (DM) intake, respectively. Body weights (BW), average daily gain (ADG), feed intake (FI), and Feed conversion ratio (FCR) were measured for the 1st experimental chapter. For the second experimental chapter; live weights (LW) of broilers were recorded before slaughter and thereafter carcass weights (CW), meat yield (weights of breast, thigh, drumstick and wing) were recorded. The dressing percentage (DP percent) was also calculated. Breast muscles were sampled for meat pH and colour measurements. The LW of birds from T1 (0 percent T. molitor L) were significantly different (P<0.05) from both T2 (5 percent T. molitor L) and T3 (10 percent T. molitor L) which were similar to each other, with T2 exhibiting the highest live weights (2166g) and the control treatment exhibiting the lowest live weights (2018.3g). In CW, T1 was significantly different (P<0.05) from T2 while it was similar (P>0.05) to T3. The dressing percent of T1 was significantly different (P<0.05) from T2 and T3 which were similar to each other, with T2 having the highest dressing percentage (78, 2 percent) and T1 having the lowest DP percent (66 percent). The breasts in T2 were significantly higher and different (P<0.05) from both T1 and T3 which were similar to each other. The drumsticks in T3 were significantly different (P<0.05) from T1 while they were similar to T2 with values with T2 having highest values. After 45 minutes of slaughter, a significant difference (P<0.05) was observed in L⃰ among all treatments. In redness (a⃰), T3 was significantly different from T1 but was similar to T2 and all treatments in this study exhibited a darker red meat, with T3 muscles exhibiting darker red colour than the other treatments. Similar results were observed in yellowness (b⃰), where the breast muscles from T3 were more yellow than the other treatments. After 24 hours of slaughter, T2 L⃰ values were significantly different (P<0.05) from both T1 and T3 which were similar to each other. It was also found that the broiler chickens given diet with no T. molitor L inclusion (T1) had lower values of BW, FI, ADG and FCR throughout the experiment than those that were in T2 and T3 with 5 percent and 10 percent T. molitor L inclusion levels, respectively. However, it was also found that although broilers with 5 percent T. molitor L inclusion (T2) in their diet had high ABW and ADG than the broilers with 10 percent T. molitor L inclusion (T3), the T3 birds compared favourably to T2 birds as they required low feed intake to reach the same slaughter weight due to high FCR. It was, therefore, concluded that T. molitor L meal can be incorporated into the diets of broilers to produce heavy birds either at 5 or 10 percent. However, although 5 percent T. molitor L inclusion yields heavier carcasses, the 10 percent T. molitor L inclusion compared favourably to 5 percent inclusion since it required low feed intake to reach the same slaughter weights and there were slight differences on meat quality attributes between the two treatments.Thus T. molitor L at 10 percent inclusion levels was the best inclusion level to enhance broiler growth performance, carcass yield, meat yield and meat quality.
- Full Text:
- Date Issued: 2015
- Authors: Mngqi, Sinethemba Census
- Date: 2015
- Subjects: Broilers (Chickens) Chickens -- Feeding and feeds Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2622 , vital:27944
- Description: This study was conducted to assess the effect of including Tenebrio molitor larvae (T. molitor L) as a protein source in different diets on broiler performance, carcass characteristics and meat quality. A total of 144 day-old Cobb-500 chicks were randomly allocated into three treatment groups, each was allocated 16 birds and reared in 9 identical pens. Experimental diets used were as follows: T1 Control (no T. molitor L inclusion); T2 and T3 contained levels of T. molitor L at 5 percent and 10 percent of dry matter (DM) intake, respectively. Body weights (BW), average daily gain (ADG), feed intake (FI), and Feed conversion ratio (FCR) were measured for the 1st experimental chapter. For the second experimental chapter; live weights (LW) of broilers were recorded before slaughter and thereafter carcass weights (CW), meat yield (weights of breast, thigh, drumstick and wing) were recorded. The dressing percentage (DP percent) was also calculated. Breast muscles were sampled for meat pH and colour measurements. The LW of birds from T1 (0 percent T. molitor L) were significantly different (P<0.05) from both T2 (5 percent T. molitor L) and T3 (10 percent T. molitor L) which were similar to each other, with T2 exhibiting the highest live weights (2166g) and the control treatment exhibiting the lowest live weights (2018.3g). In CW, T1 was significantly different (P<0.05) from T2 while it was similar (P>0.05) to T3. The dressing percent of T1 was significantly different (P<0.05) from T2 and T3 which were similar to each other, with T2 having the highest dressing percentage (78, 2 percent) and T1 having the lowest DP percent (66 percent). The breasts in T2 were significantly higher and different (P<0.05) from both T1 and T3 which were similar to each other. The drumsticks in T3 were significantly different (P<0.05) from T1 while they were similar to T2 with values with T2 having highest values. After 45 minutes of slaughter, a significant difference (P<0.05) was observed in L⃰ among all treatments. In redness (a⃰), T3 was significantly different from T1 but was similar to T2 and all treatments in this study exhibited a darker red meat, with T3 muscles exhibiting darker red colour than the other treatments. Similar results were observed in yellowness (b⃰), where the breast muscles from T3 were more yellow than the other treatments. After 24 hours of slaughter, T2 L⃰ values were significantly different (P<0.05) from both T1 and T3 which were similar to each other. It was also found that the broiler chickens given diet with no T. molitor L inclusion (T1) had lower values of BW, FI, ADG and FCR throughout the experiment than those that were in T2 and T3 with 5 percent and 10 percent T. molitor L inclusion levels, respectively. However, it was also found that although broilers with 5 percent T. molitor L inclusion (T2) in their diet had high ABW and ADG than the broilers with 10 percent T. molitor L inclusion (T3), the T3 birds compared favourably to T2 birds as they required low feed intake to reach the same slaughter weight due to high FCR. It was, therefore, concluded that T. molitor L meal can be incorporated into the diets of broilers to produce heavy birds either at 5 or 10 percent. However, although 5 percent T. molitor L inclusion yields heavier carcasses, the 10 percent T. molitor L inclusion compared favourably to 5 percent inclusion since it required low feed intake to reach the same slaughter weights and there were slight differences on meat quality attributes between the two treatments.Thus T. molitor L at 10 percent inclusion levels was the best inclusion level to enhance broiler growth performance, carcass yield, meat yield and meat quality.
- Full Text:
- Date Issued: 2015
Efficiency evaluation of South Africa tertiary education institutions using data envelopment analysis
- Authors: Chitekedza, Ignatious
- Date: 2015
- Subjects: Data envelopment analysis -- South Africa , Principal components analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4764 , vital:20674
- Description: With an increasing number of students enrolling at higher education institutions in South Africa, it has become important to investigate whether these institutions are using their resources adequately. This study uses data envelopment analysis (DEA) to estimate the efficiency of 23 South African tertiary education institutions based on both teaching and research outputs. Using DEA we are able to rank South African universities according to their use of resources in these two areas. These rankings can identify institutions which are performing well and also those which require improvement. The effect that merging institutions has on this efficiency is also determined. Owing to the limited sample size, variable reduction techniques, including the efficiency contribution measure (ECM) and principal components analysis (PCA-DEA), were used to improve the discrimination of the analysis.
- Full Text:
- Date Issued: 2015
- Authors: Chitekedza, Ignatious
- Date: 2015
- Subjects: Data envelopment analysis -- South Africa , Principal components analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4764 , vital:20674
- Description: With an increasing number of students enrolling at higher education institutions in South Africa, it has become important to investigate whether these institutions are using their resources adequately. This study uses data envelopment analysis (DEA) to estimate the efficiency of 23 South African tertiary education institutions based on both teaching and research outputs. Using DEA we are able to rank South African universities according to their use of resources in these two areas. These rankings can identify institutions which are performing well and also those which require improvement. The effect that merging institutions has on this efficiency is also determined. Owing to the limited sample size, variable reduction techniques, including the efficiency contribution measure (ECM) and principal components analysis (PCA-DEA), were used to improve the discrimination of the analysis.
- Full Text:
- Date Issued: 2015
Eliciting and combining expert opinion : an overview and comparison of methods
- Authors: Chinyamakobvu, Mutsa Carole
- Date: 2015
- Subjects: Decision making -- Statistical methods , Expertise , Bayesian statistical decision theory , Statistical decision , Delphi method , Paired comparisons (Statistics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5579 , http://hdl.handle.net/10962/d1017827
- Description: Decision makers have long relied on experts to inform their decision making. Expert judgment analysis is a way to elicit and combine the opinions of a group of experts to facilitate decision making. The use of expert judgment is most appropriate when there is a lack of data for obtaining reasonable statistical results. The experts are asked for advice by one or more decision makers who face a specific real decision problem. The decision makers are outside the group of experts and are jointly responsible and accountable for the decision and committed to finding solutions that everyone can live with. The emphasis is on the decision makers learning from the experts. The focus of this thesis is an overview and comparison of the various elicitation and combination methods available. These include the traditional committee method, the Delphi method, the paired comparisons method, the negative exponential model, Cooke’s classical model, the histogram technique, using the Dirichlet distribution in the case of a set of uncertain proportions which must sum to one, and the employment of overfitting. The supra Bayes approach, the determination of weights for the experts, and combining the opinions of experts where each opinion is associated with a confidence level that represents the expert’s conviction of his own judgment are also considered.
- Full Text:
- Date Issued: 2015
- Authors: Chinyamakobvu, Mutsa Carole
- Date: 2015
- Subjects: Decision making -- Statistical methods , Expertise , Bayesian statistical decision theory , Statistical decision , Delphi method , Paired comparisons (Statistics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5579 , http://hdl.handle.net/10962/d1017827
- Description: Decision makers have long relied on experts to inform their decision making. Expert judgment analysis is a way to elicit and combine the opinions of a group of experts to facilitate decision making. The use of expert judgment is most appropriate when there is a lack of data for obtaining reasonable statistical results. The experts are asked for advice by one or more decision makers who face a specific real decision problem. The decision makers are outside the group of experts and are jointly responsible and accountable for the decision and committed to finding solutions that everyone can live with. The emphasis is on the decision makers learning from the experts. The focus of this thesis is an overview and comparison of the various elicitation and combination methods available. These include the traditional committee method, the Delphi method, the paired comparisons method, the negative exponential model, Cooke’s classical model, the histogram technique, using the Dirichlet distribution in the case of a set of uncertain proportions which must sum to one, and the employment of overfitting. The supra Bayes approach, the determination of weights for the experts, and combining the opinions of experts where each opinion is associated with a confidence level that represents the expert’s conviction of his own judgment are also considered.
- Full Text:
- Date Issued: 2015
Enantioselective transformations using tetrol as a chiral mediator
- Authors: Dorfling, Sasha-Lee
- Date: 2015
- Subjects: Enantioselective catalysis , Trichothecenes , Catalysts , Titanium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10445 , http://hdl.handle.net/10948/d1021195
- Description: (+)-(2R,3R)-1,1,4,4-Tetraphenylbutane-1,2,3,4-tetraol (TETROL) and its derivatives were reacted with varying molar ratios of titanium isopropoxide (2:1, 1:1 and 1:2 tetraol:titanium isopropoxide) in an attempt to prepare potential titanium-based tetraol catalysts for enantioselective transformations. In each case, infrared and HNMR spectra suggested that the product was formed. We tentatively proposed that the structure of the catalyst was a spiro-type, but we could not determine conclusively what its exact structure was, despite using numerous techniques at our disposal (molecular modelling calculations, H NMR and IR spectroscopy, thermal analyses, powder diffraction, and single crystal X-ray diffraction). The catalyst and derivatives thereof were able to act catalytically for the enantioselective additions of diethylzinc compounds to aldehydes. The effects of temperature and solvent were investigated, and toluene and -78 °C were selected as optimal from the results obtained. (The reaction could, however, not be maintained at this low temperature for extended periods due to the fact that we did not have, at our disposal, the correct equipment. Each 16 h reaction was thus allowed to reach room temperature in each case.) The selectivity for the product 1-phenylpropan-1-ol (when benzaldehyde was the starting aldehyde) varied depending on the nature of the aryl substituents of the titanium-based catalyst. Using 0.2 molar equivalents of the chiral titanates, the highest selectivity was 42 percent (e.e.), but only when excess Ti(O-i-Pr)4 had been added to the reaction mixture. This was achieved with the tetra(ortho-methoxyphenyl)-TETROLate derivative. TETROL and its derivatives were also successful in metal-free catalysis where higher conversions and selectivities were observed, compared to when these were complexed to titanium. The highest selectivity was 70 percent (e.e.), achieved with the tetra(ortho-methylphenyl)TETROL derivative.
- Full Text:
- Date Issued: 2015
- Authors: Dorfling, Sasha-Lee
- Date: 2015
- Subjects: Enantioselective catalysis , Trichothecenes , Catalysts , Titanium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10445 , http://hdl.handle.net/10948/d1021195
- Description: (+)-(2R,3R)-1,1,4,4-Tetraphenylbutane-1,2,3,4-tetraol (TETROL) and its derivatives were reacted with varying molar ratios of titanium isopropoxide (2:1, 1:1 and 1:2 tetraol:titanium isopropoxide) in an attempt to prepare potential titanium-based tetraol catalysts for enantioselective transformations. In each case, infrared and HNMR spectra suggested that the product was formed. We tentatively proposed that the structure of the catalyst was a spiro-type, but we could not determine conclusively what its exact structure was, despite using numerous techniques at our disposal (molecular modelling calculations, H NMR and IR spectroscopy, thermal analyses, powder diffraction, and single crystal X-ray diffraction). The catalyst and derivatives thereof were able to act catalytically for the enantioselective additions of diethylzinc compounds to aldehydes. The effects of temperature and solvent were investigated, and toluene and -78 °C were selected as optimal from the results obtained. (The reaction could, however, not be maintained at this low temperature for extended periods due to the fact that we did not have, at our disposal, the correct equipment. Each 16 h reaction was thus allowed to reach room temperature in each case.) The selectivity for the product 1-phenylpropan-1-ol (when benzaldehyde was the starting aldehyde) varied depending on the nature of the aryl substituents of the titanium-based catalyst. Using 0.2 molar equivalents of the chiral titanates, the highest selectivity was 42 percent (e.e.), but only when excess Ti(O-i-Pr)4 had been added to the reaction mixture. This was achieved with the tetra(ortho-methoxyphenyl)-TETROLate derivative. TETROL and its derivatives were also successful in metal-free catalysis where higher conversions and selectivities were observed, compared to when these were complexed to titanium. The highest selectivity was 70 percent (e.e.), achieved with the tetra(ortho-methylphenyl)TETROL derivative.
- Full Text:
- Date Issued: 2015
Environmental flows, health and importance of macrophytes in the estuaries of water management area 11
- Authors: Cowie, Meredith
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Estuaries -- South Africa -- Management , Aquatic plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7930 , vital:24324
- Description: Estuaries require sufficient quantity, quality and appropriate timing of freshwater inflow, referred to as environmental flow requirements, to ensure adequate health and functioning. In South Africa the environmental flow requirements of estuaries is determined using Resource Directed Measures (RDM). The present health and importance of an estuary must be considered when determining the ecological flow required to maintain an estuary in its desired state. An Estuarine Health Index that quantifies changes in abiotic and biotic components from natural conditions to present day is used. Health of biotic components is assessed according to changes in species richness, abundance and community composition. There has, however, been debate regarding the calculation of these attributes. In particular, for macrophytes, the inclusion of all habitat within the Estuarine Functional Zone (i.e. 5 m topographical contour) would affect the health and changes over time determined in past assessments. This is due to different areas being included as different areas would be included The aim of this study was to test the validity and suggest improvements to South Africa’s RDM macrophyte health score determination. The health of macrophytes were assessed at varying levels of intensity from desktop studies to thorough field studies. Rapid field studies provided a visual estimate of macrophyte health; while the intermediate and comprehensive assessments quantified change by mapping the distribution of macrophyte habitats from aerial photographs. These approaches were applied to the 64 estuaries within the Mvoti-Mzimkulu Water Management Area (WMA 11), situated in KwaZulu-Natal (KZN) on the subtropical east coast. Historically, these estuaries have supported restricted macrophyte habitats. Consequently, estuaries that presently or historically supported range limited habitats such as mangroves and swamp forest are considered important. Submerged macrophytes are scarce in KZN estuaries due to siltation and low turbidity and thus estuaries supporting this macrophyte habitat are also important. Based on available literature important estuaries were highlighted and selected for field studies. Transects spanning from the estuary water channel to the boundary of the EFZ provided a generalised distribution of KZN vegetation along an elevation gradient. The transition from estuarine to terrestrial vegetation can be used to improve the current EFZ boundaries, as estuarine area has been found to occur outside of the 5 m contour in some estuaries. Results from the desktop assessment indicated that most of the estuaries are moderately modified. There was a 50 % similarity in the macrophyte health scores determined by the desktop assessment to the 2011 National Biodiversity Assessment (NBA). Field studies mostly confirmed the desktop assessment aside from seven estuaries that had different scores. There has been a significant loss of macrophyte habitat with 100% loss of certain habitats from 9 of the 22 estuaries for which there were field assessments. Submerged macrophytes were not found at any of the estuaries that were assessed in the field. Black mangroves, Bruguiera gymnorrhiza (L.) Lam., were rediscovered at Ngane Estuary, however the few individuals could not be considered a ‘mappable’ community (i.e. <0.5 ha). Mtamvuna and Mkomazi estuaries both supported small stands of mangroves that, compared to data from 2006, appeared healthy. Macrophyte habitats and surrounding coastal forest matched the species composition described in the Vegetation Map of South Africa. The freshwater mangrove or Powder puff tree, Barringtonia racemosa (L.) Roxb, was not abundant in the estuaries. It was only found at four (Damba, Fafa, Little Amanzimtoti and Mvoti) of the estuaries that were assessed in the field. Important estuaries, from a botanical perspective, included some of the larger estuaries such as Mgeni, Durban Bay and Sipingo. Smaller, healthier estuaries that presently support mangrove and swamp forest habitat were also identified as important from a botanical perspective. Macrophyte habitats have mainly been lost due to non-flow related pressures. Sugarcane cultivation occurred within the floodplain of 25% of the estuaries. Nutrient enrichment was evident for 12.5% of the estuaries and reed encroachment was evident for 27% of estuaries for which there were field assessments. Development, aside from the N2 road bridges, was evident for 40% of the estuaries assessed in the field. Invasive plant species, including aquatic invasive plants, were present in all estuaries assessed in the field. The extent of invasive plant species was related to the degree of disturbance and surrounding land use pressures. The Mkomazi and Mvoti estuaries that were assessed at a comprehensive level, as they have earmarked for further water abstraction, had the poorest macrophyte health scores. The macrophyte health of these estuaries was much lower than previously determined by the NBA. The decline in health was attributed to the removal of macrophyte habitat for sugarcane cultivation and development as well as displacement by invasive plant species. The areas covered by the macrophyte habitats also differed from the NBA highlighting the importance of updated mapping and ground truthing. Largely differing macrophyte health scores were produced when attributes were calculated using different combinations of macrophyte habitats. Results indicate that only macrophyte habitats and no other floodplain vegetation should be included when calculating abundance. All macrophyte habitats, physical habitats and floodplain should be incorporated when calculating community composition. The minimum of these attributes is used as the overall macrophyte health score as a precautionary approach is followed. Scoring of health is subjective and the only benchmark for determining the most appropriate method is comparion with previous RDM studies. This study illustrates the need for a standardised RDM scoring method that is presented in a manner that ensures the same results irregardless of the speciliast conducting the study. The updated estuary health and importance scores for WMA 11 are necessary to inform management, particularly as few of the estuaries receive formal protection. In conclusion, this study contributed to the limited knowledge of the estuaries of WMA 11 and assisted in determining appropriate methods for assessing the health and importance of estuary macrophytes.
- Full Text:
- Date Issued: 2015
- Authors: Cowie, Meredith
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Estuaries -- South Africa -- Management , Aquatic plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7930 , vital:24324
- Description: Estuaries require sufficient quantity, quality and appropriate timing of freshwater inflow, referred to as environmental flow requirements, to ensure adequate health and functioning. In South Africa the environmental flow requirements of estuaries is determined using Resource Directed Measures (RDM). The present health and importance of an estuary must be considered when determining the ecological flow required to maintain an estuary in its desired state. An Estuarine Health Index that quantifies changes in abiotic and biotic components from natural conditions to present day is used. Health of biotic components is assessed according to changes in species richness, abundance and community composition. There has, however, been debate regarding the calculation of these attributes. In particular, for macrophytes, the inclusion of all habitat within the Estuarine Functional Zone (i.e. 5 m topographical contour) would affect the health and changes over time determined in past assessments. This is due to different areas being included as different areas would be included The aim of this study was to test the validity and suggest improvements to South Africa’s RDM macrophyte health score determination. The health of macrophytes were assessed at varying levels of intensity from desktop studies to thorough field studies. Rapid field studies provided a visual estimate of macrophyte health; while the intermediate and comprehensive assessments quantified change by mapping the distribution of macrophyte habitats from aerial photographs. These approaches were applied to the 64 estuaries within the Mvoti-Mzimkulu Water Management Area (WMA 11), situated in KwaZulu-Natal (KZN) on the subtropical east coast. Historically, these estuaries have supported restricted macrophyte habitats. Consequently, estuaries that presently or historically supported range limited habitats such as mangroves and swamp forest are considered important. Submerged macrophytes are scarce in KZN estuaries due to siltation and low turbidity and thus estuaries supporting this macrophyte habitat are also important. Based on available literature important estuaries were highlighted and selected for field studies. Transects spanning from the estuary water channel to the boundary of the EFZ provided a generalised distribution of KZN vegetation along an elevation gradient. The transition from estuarine to terrestrial vegetation can be used to improve the current EFZ boundaries, as estuarine area has been found to occur outside of the 5 m contour in some estuaries. Results from the desktop assessment indicated that most of the estuaries are moderately modified. There was a 50 % similarity in the macrophyte health scores determined by the desktop assessment to the 2011 National Biodiversity Assessment (NBA). Field studies mostly confirmed the desktop assessment aside from seven estuaries that had different scores. There has been a significant loss of macrophyte habitat with 100% loss of certain habitats from 9 of the 22 estuaries for which there were field assessments. Submerged macrophytes were not found at any of the estuaries that were assessed in the field. Black mangroves, Bruguiera gymnorrhiza (L.) Lam., were rediscovered at Ngane Estuary, however the few individuals could not be considered a ‘mappable’ community (i.e. <0.5 ha). Mtamvuna and Mkomazi estuaries both supported small stands of mangroves that, compared to data from 2006, appeared healthy. Macrophyte habitats and surrounding coastal forest matched the species composition described in the Vegetation Map of South Africa. The freshwater mangrove or Powder puff tree, Barringtonia racemosa (L.) Roxb, was not abundant in the estuaries. It was only found at four (Damba, Fafa, Little Amanzimtoti and Mvoti) of the estuaries that were assessed in the field. Important estuaries, from a botanical perspective, included some of the larger estuaries such as Mgeni, Durban Bay and Sipingo. Smaller, healthier estuaries that presently support mangrove and swamp forest habitat were also identified as important from a botanical perspective. Macrophyte habitats have mainly been lost due to non-flow related pressures. Sugarcane cultivation occurred within the floodplain of 25% of the estuaries. Nutrient enrichment was evident for 12.5% of the estuaries and reed encroachment was evident for 27% of estuaries for which there were field assessments. Development, aside from the N2 road bridges, was evident for 40% of the estuaries assessed in the field. Invasive plant species, including aquatic invasive plants, were present in all estuaries assessed in the field. The extent of invasive plant species was related to the degree of disturbance and surrounding land use pressures. The Mkomazi and Mvoti estuaries that were assessed at a comprehensive level, as they have earmarked for further water abstraction, had the poorest macrophyte health scores. The macrophyte health of these estuaries was much lower than previously determined by the NBA. The decline in health was attributed to the removal of macrophyte habitat for sugarcane cultivation and development as well as displacement by invasive plant species. The areas covered by the macrophyte habitats also differed from the NBA highlighting the importance of updated mapping and ground truthing. Largely differing macrophyte health scores were produced when attributes were calculated using different combinations of macrophyte habitats. Results indicate that only macrophyte habitats and no other floodplain vegetation should be included when calculating abundance. All macrophyte habitats, physical habitats and floodplain should be incorporated when calculating community composition. The minimum of these attributes is used as the overall macrophyte health score as a precautionary approach is followed. Scoring of health is subjective and the only benchmark for determining the most appropriate method is comparion with previous RDM studies. This study illustrates the need for a standardised RDM scoring method that is presented in a manner that ensures the same results irregardless of the speciliast conducting the study. The updated estuary health and importance scores for WMA 11 are necessary to inform management, particularly as few of the estuaries receive formal protection. In conclusion, this study contributed to the limited knowledge of the estuaries of WMA 11 and assisted in determining appropriate methods for assessing the health and importance of estuary macrophytes.
- Full Text:
- Date Issued: 2015
Evaluation of incidence of Mycobacterium tuberculosis complex associated with soil, hayfeed and water in three agricultural facilities in Amathole District Municipality in the Eastern Cape Province, South Africa
- Authors: Ntloko, Athini
- Date: 2015
- Subjects: Mycobacterium tuberculosis -- South Africa -- Eastern Cape Drug resistance in microorganisms Mycobacterial diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2689 , vital:27993
- Description: Mycobacterium bovis and other species of Mycobacterium tuberculosis complex (MTBC) can result to a zoonotic infection known as Bovine tuberculosis (bTB). MTBC has members that may contaminate an extensive range of hosts, including wildlife. Diverse wild species are known to cause disease in domestic livestock and are acknowledged as TB reservoirs. It has been a main study worldwide to deliberate on bTB risk factors as a result some studies focused on particular parts of risk factors such as wildlife and herd management. The objectives of this study were to design questionnaires from commercial farms and smallholding farms; isolate and identify MTBC from collected samples using culture and PCR assays recovered from Fort Hare, Middledrift and Seven star dairy farms; and assessing genotypic drug resistance through detection of mutations conferring resistance to INH and RMP associated with first line treatment for MTBC infection. Questionnaires were administered to thirty (30) smallholding farm owners in the two villages (kwaMasele and Qungqwala) and three (3) three commercial farms (Fort Hare dairy farm, Middledrift dairy farm and Seven-star dairy farm). Detection of M. tuberculosis complex was achieved by Polymerase Chain Reaction using primers for IS6110; whereas a genotypic drug resistance mutation was detected using Genotype MTBDRplus assays. Nine percent (9 percent) of respondents had more than 40 cows in their herd, while 60 percent reported between 10 and 20 cows in their herd. Relationship between farm size and vaccination for TB differed from forty-one percent (41 percent) being the highest to the least five percent (5 percent). The highest number of respondents who knew about relationship between TB cases and cattle location was ninety-one percent (91 percent). Approximately fifty-one percent (51 percent) of respondents had knowledge about wild life access to the farms. Relationship between import of cattle and farm size ranged from nine percent (9 percent) to thirty-five percent (35 percent). Cattle sickness in relation to farm size differed from forty-three (43 percent) being the highest to the least three percent (3 percent); while thirty-three percent (33 percent) of respondents had knowledge about health management. Respondents with knowledge about the occurrence of TB infections in farms were forty-eight percent (48 percent). The frequency of DNA isolation from samples ranged from the highest forty-five percent (45 percent) from water to the least twenty-two percent (22 percent) from soil. Fort Hare dairy farm had the highest number of positive samples forty-four percent (44 percent) from water samples; whereas Middledrift dairy farm had the lowest positive from water, seventeen percent (17 percent). Twelve (22 percent) out of 55 isolates showed resistance to INH and RMP that is, multi-drug resistance (MDR) and nine percent (9 percent) were sensitive to either INH or RMP. The mutations at rpoB gene differed from 58 percent being the highest to the least (23 percent). Fifty-seven percent (57 percent) of samples showed a S315T1 mutation while only 14 percent possessed a S531L in the katG gene. The highest inhA mutations were detected in T8A (80 percent) eighty percent and the least was observed in A16G (17 percent). The results of this study reveals that risk factors for bTB in cattle and dairy farm workers is a serious issue abound in the Eastern Cape of South Africa; with the possibility of widespread dissemination of multidrug resistant determinants in MTBC from the environment.
- Full Text:
- Date Issued: 2015
- Authors: Ntloko, Athini
- Date: 2015
- Subjects: Mycobacterium tuberculosis -- South Africa -- Eastern Cape Drug resistance in microorganisms Mycobacterial diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2689 , vital:27993
- Description: Mycobacterium bovis and other species of Mycobacterium tuberculosis complex (MTBC) can result to a zoonotic infection known as Bovine tuberculosis (bTB). MTBC has members that may contaminate an extensive range of hosts, including wildlife. Diverse wild species are known to cause disease in domestic livestock and are acknowledged as TB reservoirs. It has been a main study worldwide to deliberate on bTB risk factors as a result some studies focused on particular parts of risk factors such as wildlife and herd management. The objectives of this study were to design questionnaires from commercial farms and smallholding farms; isolate and identify MTBC from collected samples using culture and PCR assays recovered from Fort Hare, Middledrift and Seven star dairy farms; and assessing genotypic drug resistance through detection of mutations conferring resistance to INH and RMP associated with first line treatment for MTBC infection. Questionnaires were administered to thirty (30) smallholding farm owners in the two villages (kwaMasele and Qungqwala) and three (3) three commercial farms (Fort Hare dairy farm, Middledrift dairy farm and Seven-star dairy farm). Detection of M. tuberculosis complex was achieved by Polymerase Chain Reaction using primers for IS6110; whereas a genotypic drug resistance mutation was detected using Genotype MTBDRplus assays. Nine percent (9 percent) of respondents had more than 40 cows in their herd, while 60 percent reported between 10 and 20 cows in their herd. Relationship between farm size and vaccination for TB differed from forty-one percent (41 percent) being the highest to the least five percent (5 percent). The highest number of respondents who knew about relationship between TB cases and cattle location was ninety-one percent (91 percent). Approximately fifty-one percent (51 percent) of respondents had knowledge about wild life access to the farms. Relationship between import of cattle and farm size ranged from nine percent (9 percent) to thirty-five percent (35 percent). Cattle sickness in relation to farm size differed from forty-three (43 percent) being the highest to the least three percent (3 percent); while thirty-three percent (33 percent) of respondents had knowledge about health management. Respondents with knowledge about the occurrence of TB infections in farms were forty-eight percent (48 percent). The frequency of DNA isolation from samples ranged from the highest forty-five percent (45 percent) from water to the least twenty-two percent (22 percent) from soil. Fort Hare dairy farm had the highest number of positive samples forty-four percent (44 percent) from water samples; whereas Middledrift dairy farm had the lowest positive from water, seventeen percent (17 percent). Twelve (22 percent) out of 55 isolates showed resistance to INH and RMP that is, multi-drug resistance (MDR) and nine percent (9 percent) were sensitive to either INH or RMP. The mutations at rpoB gene differed from 58 percent being the highest to the least (23 percent). Fifty-seven percent (57 percent) of samples showed a S315T1 mutation while only 14 percent possessed a S531L in the katG gene. The highest inhA mutations were detected in T8A (80 percent) eighty percent and the least was observed in A16G (17 percent). The results of this study reveals that risk factors for bTB in cattle and dairy farm workers is a serious issue abound in the Eastern Cape of South Africa; with the possibility of widespread dissemination of multidrug resistant determinants in MTBC from the environment.
- Full Text:
- Date Issued: 2015
Exploration status for oxide and sulphide zinc ores at Skorpion Zinc Mine, Namibia
- Authors: Sitoka, Stefanus
- Date: 2015
- Subjects: Scorpion Zinc Mine (Namibia) , Zinc ores , Oxide minerals , Sulfide minerals , Zinc mines and mining -- Namibia , Prospecting -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5087 , http://hdl.handle.net/10962/d1018204
- Description: The thesis is inspired by recent interests in oxide zinc ores caused by new developments in the technology of hydrometallurgy. The improved techniques turned the non-sulphide zinc ores in to attractive exploration targets due to a number of advantages such as low metal recovery costs and favorable environmental aspects such as the obvious absence of sulfur (Large, 2001). Historically extraction of zinc metal from oxide ores was not possible until recently. The metallurgical complexity resulted in a lack of interest and hence some economic oxide zinc ores might have been missed by conventional exploration techniques. The study presents a review of exploration status at Skorpion mine based on different exploration techniques and their application to sulphide and oxide zinc ore exploration. The challenge facing the mineral exploration industry today is the inability to detect mineral deposits under cover. Therefore a key to successful exploration program lies in the selection of the right exploration technique. Important parameters that should be highlighted in the exploration methodology are the geological situation of an area, equipment applicability and effectiveness, survey limitation, equipment mobilization and the safety aspects involved. The aim of this thesis is to provide a general guideline for sulphide and non-sulphide zinc ore exploration on the Skorpion area and other similar geological environments. Geochemical surveys appears to be more complimentary in exploration of non-sulphide zinc exploration. Although geochemical techniques are preferred, it is equally important to choose the right soil horizon. Furthermore, sample media may mean the difference between success and failure in geochemical exploration of non-sulphide zinc mineralization, due to high mobility of zinc in the surficial environment. On cost comparison, surface geochemical surveys programs are more cost effective except for litho-geochemical sampling which are commonly carried out through subsurface drilling. Geophysical techniques have limited application in exploration of non-sulphide zinc mineralization due to a lack of major physical properties (e.g., magnetic and electrical properties) in non-sulphides unlike their sulphide counterparts. However geophysical methods are commendable in delineating massive and disseminated sulphides mainly if they are associated with major Fe minerals (pyrrhotite or magnetite). In addition, geophysical techniques may be effective in mapping of subsurface primary and secondary structures such as basin faults which might have acted as pathways for metal-rich fluids. Terms non-sulphide and oxide zinc mineralization are used interchangeably throughout the thesis. Recommendations on regional and local target generation are presented in the thesis to give some basic guide lines on target generation strategies. The most important conclusion reached in this study is that, success in exploration for non-sulphide or sulphide zinc mineralization might be enhanced through the integrated exploration methodology.
- Full Text:
- Date Issued: 2015
- Authors: Sitoka, Stefanus
- Date: 2015
- Subjects: Scorpion Zinc Mine (Namibia) , Zinc ores , Oxide minerals , Sulfide minerals , Zinc mines and mining -- Namibia , Prospecting -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5087 , http://hdl.handle.net/10962/d1018204
- Description: The thesis is inspired by recent interests in oxide zinc ores caused by new developments in the technology of hydrometallurgy. The improved techniques turned the non-sulphide zinc ores in to attractive exploration targets due to a number of advantages such as low metal recovery costs and favorable environmental aspects such as the obvious absence of sulfur (Large, 2001). Historically extraction of zinc metal from oxide ores was not possible until recently. The metallurgical complexity resulted in a lack of interest and hence some economic oxide zinc ores might have been missed by conventional exploration techniques. The study presents a review of exploration status at Skorpion mine based on different exploration techniques and their application to sulphide and oxide zinc ore exploration. The challenge facing the mineral exploration industry today is the inability to detect mineral deposits under cover. Therefore a key to successful exploration program lies in the selection of the right exploration technique. Important parameters that should be highlighted in the exploration methodology are the geological situation of an area, equipment applicability and effectiveness, survey limitation, equipment mobilization and the safety aspects involved. The aim of this thesis is to provide a general guideline for sulphide and non-sulphide zinc ore exploration on the Skorpion area and other similar geological environments. Geochemical surveys appears to be more complimentary in exploration of non-sulphide zinc exploration. Although geochemical techniques are preferred, it is equally important to choose the right soil horizon. Furthermore, sample media may mean the difference between success and failure in geochemical exploration of non-sulphide zinc mineralization, due to high mobility of zinc in the surficial environment. On cost comparison, surface geochemical surveys programs are more cost effective except for litho-geochemical sampling which are commonly carried out through subsurface drilling. Geophysical techniques have limited application in exploration of non-sulphide zinc mineralization due to a lack of major physical properties (e.g., magnetic and electrical properties) in non-sulphides unlike their sulphide counterparts. However geophysical methods are commendable in delineating massive and disseminated sulphides mainly if they are associated with major Fe minerals (pyrrhotite or magnetite). In addition, geophysical techniques may be effective in mapping of subsurface primary and secondary structures such as basin faults which might have acted as pathways for metal-rich fluids. Terms non-sulphide and oxide zinc mineralization are used interchangeably throughout the thesis. Recommendations on regional and local target generation are presented in the thesis to give some basic guide lines on target generation strategies. The most important conclusion reached in this study is that, success in exploration for non-sulphide or sulphide zinc mineralization might be enhanced through the integrated exploration methodology.
- Full Text:
- Date Issued: 2015
Exploring the development of an integrated, participative, water quality management process for the Crocodile River catchment, focusing on the sugar industry
- Authors: Sahula, Asiphe
- Date: 2015
- Subjects: Water quality management -- South Africa -- Krokodilrivier (Mpumalanga) , Watersheds -- South Africa -- Krokodilrivier (Mpumalanga) , Integrated water development -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality management -- Social aspects -- South Africa -- Krokodilrivier (Mpumalanga) , Social responsibility of business -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality -- South Africa -- Krokodilrivier (Mpumalanga)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6051 , http://hdl.handle.net/10962/d1017876
- Description: Water quality deterioration is reaching crisis proportions in South Africa. Many South African catchments are over-allocated, and decreasing volumes of source water mean increasing concentrations of pollutants. The Crocodile River Catchment in the Mpumalanga province in South Africa was identified through previous research, as a catchment faced with deteriorating source water quality for water users in the catchment. Poor source water quality has become a sufficiently acute concern for the stakeholders in this catchment to co-operate in developing a process that assists with compliance control of their water use and waste disposal to reduce costs, decrease industrial risks as water quality compliance increases, and improve source water quality. The sugar industry is downstream within the Crocodile River Catchment, and is affected by the activities of all upstream water users; the industry is thus dependent on the stakeholders upstream participating in the effective management of the resource. However, the sugar industry is also located just before the confluence of the Crocodile River and Komati River upstream of the Mozambique border, and thus the water quality of the sugar industry effluent will affect the quality of the water that flows into Mozambique. The sugar industry is on the opposite river bank to the Kruger National Park, which has high water resource protection goals. Therefore, the sugar industry has a national role to play in the management of water resources in the Crocodile River Catchment. This study provides a focused view of the role of the sugar industry in the development of a co-operative, integrated water quality management process (IWQMP) in the Crocodile River Catchment. In order to address the objectives of this study, this research drew from an understanding of the social processes that influence water management practices within the sugar industry as well as social processes that influence the role of the Inkomati-Usuthu Catchment Management Agency as the main governing institution in water resource management in the Inkomati Water Management Area. The study also drew from an understanding of scientific knowledge in terms of a water chemistry which describes the upstream and downstream water quality impacts related to the sugar industry. The water quality analysis for the Lower Crocodile River Catchment shows a decline in water quality in terms of Total Dissolved Solids (TDS) loads when moving from below Mbombela to the Mozambique border. The major sources of TDS in the Lower Crocodile River are point source dominated, which may be attributed to the extensive mining, industrial and municipal activities that occur across the catchment. When observing Total Alkalinity (TAL) and pH values from below Mbombela to the furthest monitoring point, there is deterioration in the quality of the water in the Lower Crocodile River, with the Kaap River contributing a negative effect that is diluted by the Crocodile main stem. The Hectorspruit Waste Water Treatment Works (WWTWs) (located in the Lower Crocodile River Catchment) contributes high concentrations of TDS and TAL into the Crocodile River. Total Inorganic Nitrogen and Soluble Reactive Phosphorus concentrations decrease in the lower reaches of the Crocodile River compared with the river below Mbombela, which can be attributed to the extensive sugar cane plantations located in the Lower Crocodile River Catchment acting as an “agricultural wetland” that serves a function of bioremediation resulting in large scale absorption of nutrients. This is an interesting result as earlier assumptions were that fertiliser application would result in an overall increase in nutrient loads and concentrations. Biomonitoring data show no substantial change in aquatic health in the LowerCrocodile River Catchment. For a catchment that has an extensive agricultural land use in terms of sugarcane and citrus production, the Crocodile River is unexpectedly not in a toxic state in terms of aquatic health. This is a positive result and it suggests that pesticide use is strictly controlled in the sugar and citrus industry in the Crocodile River Catchment. For long term sustainability, it is essential for the sugar industry to maintain (and possibly improve) this pesticide management. The social component of this study aimed to provide an analysis of the management practices of the sugar mill as well as examining agricultural practices in the sugar cane fields in relation to water quality management through the use of Cultural Historical Activity System Theory (CHAT). This component showed that there are contradictions within the sugar industry activity system that are considered to be areas of “tension” that can be loosened or focused on to improve the contribution the sugar industry can make to the IWQMP. Surfacing contradictions within the sugar industry activity system and the Inkomati-Usuthu Catchment Management Agency activity systems highlighted areas of potential for learning and change. While an understanding of biophysical processes through scientific knowledge is critical in water management decision making, it is evident that an understanding of other actors, institutions and networks that inform water quality management decision-making also plays a significant role. The notion of improving the role of scientific or biophysical knowledge in contributing to socio-ecologically robust knowledge co-creation, decisions and actions towards resolving water quality problems is emphasised. Specifically, moving towards improving interactions between scientists and other actors (water users in the Crocodile Catchment in this case), so that scientific practices become more orientated towards societal platforms where water quality management is tackled to enable improved water quality management practices. Therefore, linking the social and biophysical components in this study provides a holistic understanding of how the sugar industry can contribute to the development of an IWQMP for the Crocodile River catchment.
- Full Text:
- Date Issued: 2015
- Authors: Sahula, Asiphe
- Date: 2015
- Subjects: Water quality management -- South Africa -- Krokodilrivier (Mpumalanga) , Watersheds -- South Africa -- Krokodilrivier (Mpumalanga) , Integrated water development -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality management -- Social aspects -- South Africa -- Krokodilrivier (Mpumalanga) , Social responsibility of business -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality -- South Africa -- Krokodilrivier (Mpumalanga)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6051 , http://hdl.handle.net/10962/d1017876
- Description: Water quality deterioration is reaching crisis proportions in South Africa. Many South African catchments are over-allocated, and decreasing volumes of source water mean increasing concentrations of pollutants. The Crocodile River Catchment in the Mpumalanga province in South Africa was identified through previous research, as a catchment faced with deteriorating source water quality for water users in the catchment. Poor source water quality has become a sufficiently acute concern for the stakeholders in this catchment to co-operate in developing a process that assists with compliance control of their water use and waste disposal to reduce costs, decrease industrial risks as water quality compliance increases, and improve source water quality. The sugar industry is downstream within the Crocodile River Catchment, and is affected by the activities of all upstream water users; the industry is thus dependent on the stakeholders upstream participating in the effective management of the resource. However, the sugar industry is also located just before the confluence of the Crocodile River and Komati River upstream of the Mozambique border, and thus the water quality of the sugar industry effluent will affect the quality of the water that flows into Mozambique. The sugar industry is on the opposite river bank to the Kruger National Park, which has high water resource protection goals. Therefore, the sugar industry has a national role to play in the management of water resources in the Crocodile River Catchment. This study provides a focused view of the role of the sugar industry in the development of a co-operative, integrated water quality management process (IWQMP) in the Crocodile River Catchment. In order to address the objectives of this study, this research drew from an understanding of the social processes that influence water management practices within the sugar industry as well as social processes that influence the role of the Inkomati-Usuthu Catchment Management Agency as the main governing institution in water resource management in the Inkomati Water Management Area. The study also drew from an understanding of scientific knowledge in terms of a water chemistry which describes the upstream and downstream water quality impacts related to the sugar industry. The water quality analysis for the Lower Crocodile River Catchment shows a decline in water quality in terms of Total Dissolved Solids (TDS) loads when moving from below Mbombela to the Mozambique border. The major sources of TDS in the Lower Crocodile River are point source dominated, which may be attributed to the extensive mining, industrial and municipal activities that occur across the catchment. When observing Total Alkalinity (TAL) and pH values from below Mbombela to the furthest monitoring point, there is deterioration in the quality of the water in the Lower Crocodile River, with the Kaap River contributing a negative effect that is diluted by the Crocodile main stem. The Hectorspruit Waste Water Treatment Works (WWTWs) (located in the Lower Crocodile River Catchment) contributes high concentrations of TDS and TAL into the Crocodile River. Total Inorganic Nitrogen and Soluble Reactive Phosphorus concentrations decrease in the lower reaches of the Crocodile River compared with the river below Mbombela, which can be attributed to the extensive sugar cane plantations located in the Lower Crocodile River Catchment acting as an “agricultural wetland” that serves a function of bioremediation resulting in large scale absorption of nutrients. This is an interesting result as earlier assumptions were that fertiliser application would result in an overall increase in nutrient loads and concentrations. Biomonitoring data show no substantial change in aquatic health in the LowerCrocodile River Catchment. For a catchment that has an extensive agricultural land use in terms of sugarcane and citrus production, the Crocodile River is unexpectedly not in a toxic state in terms of aquatic health. This is a positive result and it suggests that pesticide use is strictly controlled in the sugar and citrus industry in the Crocodile River Catchment. For long term sustainability, it is essential for the sugar industry to maintain (and possibly improve) this pesticide management. The social component of this study aimed to provide an analysis of the management practices of the sugar mill as well as examining agricultural practices in the sugar cane fields in relation to water quality management through the use of Cultural Historical Activity System Theory (CHAT). This component showed that there are contradictions within the sugar industry activity system that are considered to be areas of “tension” that can be loosened or focused on to improve the contribution the sugar industry can make to the IWQMP. Surfacing contradictions within the sugar industry activity system and the Inkomati-Usuthu Catchment Management Agency activity systems highlighted areas of potential for learning and change. While an understanding of biophysical processes through scientific knowledge is critical in water management decision making, it is evident that an understanding of other actors, institutions and networks that inform water quality management decision-making also plays a significant role. The notion of improving the role of scientific or biophysical knowledge in contributing to socio-ecologically robust knowledge co-creation, decisions and actions towards resolving water quality problems is emphasised. Specifically, moving towards improving interactions between scientists and other actors (water users in the Crocodile Catchment in this case), so that scientific practices become more orientated towards societal platforms where water quality management is tackled to enable improved water quality management practices. Therefore, linking the social and biophysical components in this study provides a holistic understanding of how the sugar industry can contribute to the development of an IWQMP for the Crocodile River catchment.
- Full Text:
- Date Issued: 2015
Factors affecting the success of reseeding rehabilitation in the semi-arid Karoo, South Africa
- Authors: Matthee, Willem
- Date: 2015
- Subjects: Ecological disturbances -- South Africa -- Karoo , Arid regions -- South Africa -- Karoo , Environmental degradation -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/2889 , vital:20360
- Description: Due to overgrazing, mining and other anthropogenic disturbances, large sections of the Karoo region have been degraded, resulting in areas with low vegetation cover, where erosion rates are high and vegetation is dominated by unpalatable species. These areas have low and unpredictable rainfall, with slow to non-existent autogenic recovery, and this often forces landowners to implement reseeding rehabilitation in an attempt to increase both overall vegetation cover and the relative abundance of palatable plants. Landowners use soil preparation treatments, which include creating micro-catchments, ripping, mulching and brush packing, to supplement land rehabilitation. This study investigated the significance of initial rainfall, mean monthly rainfall, soil preparation techniques, slope, existing vegetation cover, litter, mulch and stone cover in determining the success of reseeding rehabilitation. Rainfall had the most significant influence, where long-lived shrubs established best under low initial rainfall and high mean monthly rainfall, and grasses established best after receiving high initial rainfall. Micro-catchments proved the most successful soil preparation technique for the establishment of long-lived shrubs, while ripping and mulching impacted negatively on grass establishment. A combination of mulch and micro-catchments aided Osteospermum sinuatum establishment in soils where soil shrinkage cracks occurred. Temperature influenced seed germination and drought tolerance of Lessertia annularis, Fingerhuthia africana and O. sinuatum, with higher germination success of O. sinuatum under temperatures simulating summer, and of F. africana under temperatures simulating winter. L. annularis germination had a faster growth rate and higher survival when germinated under autumn/spring temperatures. Landowners are advised to sow seeds of more than one species during rehabilitation, to include micro-catchments as soil preparation treatment, and to sow seeds during a time when rainfall is predicted to be high.
- Full Text:
- Date Issued: 2015
- Authors: Matthee, Willem
- Date: 2015
- Subjects: Ecological disturbances -- South Africa -- Karoo , Arid regions -- South Africa -- Karoo , Environmental degradation -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/2889 , vital:20360
- Description: Due to overgrazing, mining and other anthropogenic disturbances, large sections of the Karoo region have been degraded, resulting in areas with low vegetation cover, where erosion rates are high and vegetation is dominated by unpalatable species. These areas have low and unpredictable rainfall, with slow to non-existent autogenic recovery, and this often forces landowners to implement reseeding rehabilitation in an attempt to increase both overall vegetation cover and the relative abundance of palatable plants. Landowners use soil preparation treatments, which include creating micro-catchments, ripping, mulching and brush packing, to supplement land rehabilitation. This study investigated the significance of initial rainfall, mean monthly rainfall, soil preparation techniques, slope, existing vegetation cover, litter, mulch and stone cover in determining the success of reseeding rehabilitation. Rainfall had the most significant influence, where long-lived shrubs established best under low initial rainfall and high mean monthly rainfall, and grasses established best after receiving high initial rainfall. Micro-catchments proved the most successful soil preparation technique for the establishment of long-lived shrubs, while ripping and mulching impacted negatively on grass establishment. A combination of mulch and micro-catchments aided Osteospermum sinuatum establishment in soils where soil shrinkage cracks occurred. Temperature influenced seed germination and drought tolerance of Lessertia annularis, Fingerhuthia africana and O. sinuatum, with higher germination success of O. sinuatum under temperatures simulating summer, and of F. africana under temperatures simulating winter. L. annularis germination had a faster growth rate and higher survival when germinated under autumn/spring temperatures. Landowners are advised to sow seeds of more than one species during rehabilitation, to include micro-catchments as soil preparation treatment, and to sow seeds during a time when rainfall is predicted to be high.
- Full Text:
- Date Issued: 2015