A standardised protocol for roadkill detection and the determinants of roadkill in the greater Mapungubwe Transfrontier Conservation Area, Limpopo Province, South Africa
- Authors: Collinson, Wendy Jane
- Date: 2013
- Subjects: Roadkill -- South Africa -- Mapungubwe Site , Traffic safety and wildlife -- South Africa -- Mapungubwe Site
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5606 , http://hdl.handle.net/10962/d1002056 , Roadkill -- South Africa -- Mapungubwe Site , Traffic safety and wildlife -- South Africa -- Mapungubwe Site
- Description: Despite evidence suggesting that road traffic is a major threat to biodiversity loss, very little is known about its actual impact on wildlife populations in South Africa. Globally, road density and traffic volumes are increasing, and although huge budgets are devoted to the construction and upgrading of roads, there is little or no allocation to mitigation measures for protecting fauna in most countries, particularly Africa. Further, no global standardised protocol exists for the rapid assessment of roadkill or the most economical and efficient approach for assessing roadkill rates. Using vehicle field trials, the reliability of detecting artificially deployed roadkill was assessed. Roadkill detection rates decreased significantly at speeds >50 km/h and were also significantly influenced by light conditions (i.e. detection success was greater when the sun was high) and the position of the roadkill on the road (i.e. smaller roadkill on verges were often missed). These results suggest that roadkill sampling was most effective between 1.5 hours after dawn and 1.5 hours before dusk and that driving at slower speeds (<50 km.h⁻ₑ) was required to detect roadkill. This protocol was implemented across three ecological seasons on a 100 km paved road and a 20 km unpaved road in the Greater Mapungubwe Transfrontier Conservation Area, Limpopo Province, South Africa. Driven daily over a 120-day period (three periods consisting each of 40 days), a total of 1,027 roadkill were recorded. These comprised 162 species from all terrestrial vertebrate groups with birds being the most commonly encountered roadkill (50% of all incidents). The high numbers of vertebrates identified as roadkill suggests that road traffic could have potentially unsustainable impacts on wildlife populations and hence the biodiversity of the area. Seventeen variables were identified as possible determinants of roadkill occurrence with season, rainfall, minimum and maximum temperature, habitat type, grass height, grass density, fence type and vehicle type significantly influencing roadkill numbers. Significantly more roadkill were detected on the paved road (9.91/100km) than on the unpaved road (1.8/100km) probably because of greater traffic volumes and the increased speed that vehicles travelled on the paved road. Warmer temperatures and increased rainfall in the preceding 24 hours also increased road mortality numbers as animals tended to become more active during these times. Interestingly, more roadkill was detected in open roadside habitats compared to dense roadside habitats on both the paved and unpaved roads and when grass on the roadside verge was of intermediate height. Open habitat possibly may provide a natural corridor for wildlife which ultimately end up on the road. Roadkill numbers increased when certain other physical barriers, such as cattle fences, were present, probably because these barriers were more penetrable than electric fencing. A series of mitigation measures are proposed to reduce the impacts of roads on wildlife in South Africa. These mitigation measures highlight the need to address the balance between the development of a country’s transport infrastructure and the conservation of its fauna. It is important that research on the impacts of roads becomes standardised to enable robust statistical comparisons which will provide a greater understanding of the potential threats to vertebrate biodiversity
- Full Text:
- Date Issued: 2013
- Authors: Collinson, Wendy Jane
- Date: 2013
- Subjects: Roadkill -- South Africa -- Mapungubwe Site , Traffic safety and wildlife -- South Africa -- Mapungubwe Site
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5606 , http://hdl.handle.net/10962/d1002056 , Roadkill -- South Africa -- Mapungubwe Site , Traffic safety and wildlife -- South Africa -- Mapungubwe Site
- Description: Despite evidence suggesting that road traffic is a major threat to biodiversity loss, very little is known about its actual impact on wildlife populations in South Africa. Globally, road density and traffic volumes are increasing, and although huge budgets are devoted to the construction and upgrading of roads, there is little or no allocation to mitigation measures for protecting fauna in most countries, particularly Africa. Further, no global standardised protocol exists for the rapid assessment of roadkill or the most economical and efficient approach for assessing roadkill rates. Using vehicle field trials, the reliability of detecting artificially deployed roadkill was assessed. Roadkill detection rates decreased significantly at speeds >50 km/h and were also significantly influenced by light conditions (i.e. detection success was greater when the sun was high) and the position of the roadkill on the road (i.e. smaller roadkill on verges were often missed). These results suggest that roadkill sampling was most effective between 1.5 hours after dawn and 1.5 hours before dusk and that driving at slower speeds (<50 km.h⁻ₑ) was required to detect roadkill. This protocol was implemented across three ecological seasons on a 100 km paved road and a 20 km unpaved road in the Greater Mapungubwe Transfrontier Conservation Area, Limpopo Province, South Africa. Driven daily over a 120-day period (three periods consisting each of 40 days), a total of 1,027 roadkill were recorded. These comprised 162 species from all terrestrial vertebrate groups with birds being the most commonly encountered roadkill (50% of all incidents). The high numbers of vertebrates identified as roadkill suggests that road traffic could have potentially unsustainable impacts on wildlife populations and hence the biodiversity of the area. Seventeen variables were identified as possible determinants of roadkill occurrence with season, rainfall, minimum and maximum temperature, habitat type, grass height, grass density, fence type and vehicle type significantly influencing roadkill numbers. Significantly more roadkill were detected on the paved road (9.91/100km) than on the unpaved road (1.8/100km) probably because of greater traffic volumes and the increased speed that vehicles travelled on the paved road. Warmer temperatures and increased rainfall in the preceding 24 hours also increased road mortality numbers as animals tended to become more active during these times. Interestingly, more roadkill was detected in open roadside habitats compared to dense roadside habitats on both the paved and unpaved roads and when grass on the roadside verge was of intermediate height. Open habitat possibly may provide a natural corridor for wildlife which ultimately end up on the road. Roadkill numbers increased when certain other physical barriers, such as cattle fences, were present, probably because these barriers were more penetrable than electric fencing. A series of mitigation measures are proposed to reduce the impacts of roads on wildlife in South Africa. These mitigation measures highlight the need to address the balance between the development of a country’s transport infrastructure and the conservation of its fauna. It is important that research on the impacts of roads becomes standardised to enable robust statistical comparisons which will provide a greater understanding of the potential threats to vertebrate biodiversity
- Full Text:
- Date Issued: 2013
An assessment of urban residents' knowledge and appreciation of the intangible benefits of trees in two medium sized towns in South Africa
- Authors: Chinyimba, Abby
- Date: 2013
- Subjects: Trees in cities -- South Africa--Limpopo , Cities and towns -- South Africa -- Limpopo , Ecology -- South Africa -- Limpopo , Human-plant relationships -- South Africa -- Limpopo , Plants and civilization -- South Africa -- Limpopo , Willingness to pay -- South Africa -- Limpopo , Limpopo (South Africa) -- Environmental conditions , Cultural importance , Cultural and regulating services , Intangible benefits , Urban systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4730 , http://hdl.handle.net/10962/d1001957
- Description: In order to meet the different public needs and requirements of contemporary urban society, a better understanding of public perceptions, appreciation and knowledge of the assorted values derived from urban trees is beneficial for improved urban greening. Thus, this study carried out an assessment of urban residents’ knowledge and appreciation of the benefits of trees and the role they play in enhancing the quality of life in urban systems. The study primarily focused on the intangible benefits (also referred to as cultural and regulating services) of urban trees, because most research to date in South Africa on trees and the benefits derived from them is biased towards the provisioning services of trees in rural areas. The significance and contribution of the intangible benefits of trees in urban systems is often underestimated and not seriously taken into account by urban planners, policy makers and other key decision makers. The study was conducted in three different residential settlement types (formal townships, RDP settlements and informal settlements) in two towns in the Limpopo Province in South Africa, namely Bela-Bela and Tzaneen. Findings revealed that the intangible benefits of trees are seen to play a significant role in improving both residents’ quality of life and the environmental conditions in cities, including the preservation of biodiversity. Findings also showed that urban residents had strong spiritual connections with trees and placed considerable cultural and historical importance on specific tree species and individual trees. Urban residents in both towns had moderate knowledge of the intangible benefits of trees based on the knowledge score that was created for the purposes of this study. Fifty seven percent of the residents had ‘reasonable’ knowledge of some of the intangible benefits of trees, while 43% had low levels of knowledge. That said, the majority of residents demonstrated high appreciation (98%) of the intangible benefits of trees (especially social and cultural values), with few residents not recognising these, suggesting that knowledge does not necessarily lead to appreciation. Age and level of education were found to influence knowledge of the intangible benefits of trees. A large proportion (86%) of residents who possessed tertiary level qualifications had more knowledge of the intangible benefits of trees as compared to residents with no formal education. Findings also revealed that younger respondents (60%) had more knowledge of the intangible benefits of trees. Factors that influenced appreciation of the intangible benefits of trees included links to crime, peoples’ value systems (their pro-environmental and altruistic values) and residential settlement type. Sixty five percent of residents in both towns felt that urban street trees and trees in public spaces attract criminals and promote crime, while 67% of RDP and 96% of informal township residents did not use or appreciate the social and recreational benefits of trees mainly because of the absence or long distances to public parks. A Willingness To Pay (WTP) survey revealed that a high proportion of residents in Bela-Bela (86%) were WTP a small annual fee in order to sustain greening initiatives in their communities compared to the residents in Tzaneen (53%). In terms of the planting and retention of trees, it was found that 300 households in both study towns had planted and retained a total of 1 615 trees in spite of the various factors that negatively influenced planting and retention of trees such as residency time and tenure security. The majority (66%) of informal township residents said tenure security was an important factor to consider when making tree planting decisions, while this was not an issue for formal township and RDP residents. Policy implications and recommendations are presented to help municipalities and urban planners improve and develop effective policies and programmes that will enable implementation of sustainable urban greening programmes
- Full Text:
- Date Issued: 2013
- Authors: Chinyimba, Abby
- Date: 2013
- Subjects: Trees in cities -- South Africa--Limpopo , Cities and towns -- South Africa -- Limpopo , Ecology -- South Africa -- Limpopo , Human-plant relationships -- South Africa -- Limpopo , Plants and civilization -- South Africa -- Limpopo , Willingness to pay -- South Africa -- Limpopo , Limpopo (South Africa) -- Environmental conditions , Cultural importance , Cultural and regulating services , Intangible benefits , Urban systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4730 , http://hdl.handle.net/10962/d1001957
- Description: In order to meet the different public needs and requirements of contemporary urban society, a better understanding of public perceptions, appreciation and knowledge of the assorted values derived from urban trees is beneficial for improved urban greening. Thus, this study carried out an assessment of urban residents’ knowledge and appreciation of the benefits of trees and the role they play in enhancing the quality of life in urban systems. The study primarily focused on the intangible benefits (also referred to as cultural and regulating services) of urban trees, because most research to date in South Africa on trees and the benefits derived from them is biased towards the provisioning services of trees in rural areas. The significance and contribution of the intangible benefits of trees in urban systems is often underestimated and not seriously taken into account by urban planners, policy makers and other key decision makers. The study was conducted in three different residential settlement types (formal townships, RDP settlements and informal settlements) in two towns in the Limpopo Province in South Africa, namely Bela-Bela and Tzaneen. Findings revealed that the intangible benefits of trees are seen to play a significant role in improving both residents’ quality of life and the environmental conditions in cities, including the preservation of biodiversity. Findings also showed that urban residents had strong spiritual connections with trees and placed considerable cultural and historical importance on specific tree species and individual trees. Urban residents in both towns had moderate knowledge of the intangible benefits of trees based on the knowledge score that was created for the purposes of this study. Fifty seven percent of the residents had ‘reasonable’ knowledge of some of the intangible benefits of trees, while 43% had low levels of knowledge. That said, the majority of residents demonstrated high appreciation (98%) of the intangible benefits of trees (especially social and cultural values), with few residents not recognising these, suggesting that knowledge does not necessarily lead to appreciation. Age and level of education were found to influence knowledge of the intangible benefits of trees. A large proportion (86%) of residents who possessed tertiary level qualifications had more knowledge of the intangible benefits of trees as compared to residents with no formal education. Findings also revealed that younger respondents (60%) had more knowledge of the intangible benefits of trees. Factors that influenced appreciation of the intangible benefits of trees included links to crime, peoples’ value systems (their pro-environmental and altruistic values) and residential settlement type. Sixty five percent of residents in both towns felt that urban street trees and trees in public spaces attract criminals and promote crime, while 67% of RDP and 96% of informal township residents did not use or appreciate the social and recreational benefits of trees mainly because of the absence or long distances to public parks. A Willingness To Pay (WTP) survey revealed that a high proportion of residents in Bela-Bela (86%) were WTP a small annual fee in order to sustain greening initiatives in their communities compared to the residents in Tzaneen (53%). In terms of the planting and retention of trees, it was found that 300 households in both study towns had planted and retained a total of 1 615 trees in spite of the various factors that negatively influenced planting and retention of trees such as residency time and tenure security. The majority (66%) of informal township residents said tenure security was an important factor to consider when making tree planting decisions, while this was not an issue for formal township and RDP residents. Policy implications and recommendations are presented to help municipalities and urban planners improve and develop effective policies and programmes that will enable implementation of sustainable urban greening programmes
- Full Text:
- Date Issued: 2013
An experimental and theoretical investigation of unstable Fischer chromium carbene complexes
- Authors: Makanjee, Che Azad
- Date: 2013 , 2013-03-27
- Subjects: Chromium , Organolithium compounds , Carbenes (Methylene compounds) , Organometallic chemistry , Organometallic compounds , Organochromium compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4284 , http://hdl.handle.net/10962/d1002953 , Chromium , Organolithium compounds , Carbenes (Methylene compounds) , Organometallic chemistry , Organometallic compounds , Organochromium compounds
- Description: This organometallic study involves the use organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are typically electrophilic and are stabilized by a single π-donor substituent, and contain low oxidation state metals (often but not always from Group 6). They are highly reactive and can give access to a range of biologically active compounds through cyclopropanations, insertions, coupling and photochemical reactions. Synthesis and characterization of three MOM-protected α-alkoxy organostannanes was successfully carried out via a nucleophilic addition of tributylstannyllithium to suitable aldehydes, and immediate protection of the alcohol with MOM. Two N-BOC protected α-amino organostannanes were successfully synthesized and characterized via α-lithiation and tin-lithium exchange in the presence of TMEDA. Tin-lithium transmetallation of the organostannanes allowed access to the organolithiums required for the synthesis of novel Fischer carbenes. Addition of chromium hexacarbonyl to the organolithiums formed the acylpentacarbonyl chromate salt which was alkylated with Meerwein salt, resulting in the Fischer carbene and a by-product, tetrabutyltin, which proved difficult to remove. Several Fischer carbenes were synthesized and characterized, some simple and known and some novel. In silico work explored the reaction coordinate of the [2+2] cycloaddition towards the formation of β-lactams, and the photoactivation cycle that precedes this process. Computational work also showed the effect of the ligand on the stability and reactivity of the carbene. It was found that in some cases the oxygen on the ligand could negatively influence the stability of the carbene (when compared to a simple methyl carbene). A link between bond orders and back donation in Fischer carbenes was explored in an attempt to theoretically predict the stability of a range of carbenes. , Microsoft� Office Word 2007
- Full Text:
- Date Issued: 2013
- Authors: Makanjee, Che Azad
- Date: 2013 , 2013-03-27
- Subjects: Chromium , Organolithium compounds , Carbenes (Methylene compounds) , Organometallic chemistry , Organometallic compounds , Organochromium compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4284 , http://hdl.handle.net/10962/d1002953 , Chromium , Organolithium compounds , Carbenes (Methylene compounds) , Organometallic chemistry , Organometallic compounds , Organochromium compounds
- Description: This organometallic study involves the use organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are typically electrophilic and are stabilized by a single π-donor substituent, and contain low oxidation state metals (often but not always from Group 6). They are highly reactive and can give access to a range of biologically active compounds through cyclopropanations, insertions, coupling and photochemical reactions. Synthesis and characterization of three MOM-protected α-alkoxy organostannanes was successfully carried out via a nucleophilic addition of tributylstannyllithium to suitable aldehydes, and immediate protection of the alcohol with MOM. Two N-BOC protected α-amino organostannanes were successfully synthesized and characterized via α-lithiation and tin-lithium exchange in the presence of TMEDA. Tin-lithium transmetallation of the organostannanes allowed access to the organolithiums required for the synthesis of novel Fischer carbenes. Addition of chromium hexacarbonyl to the organolithiums formed the acylpentacarbonyl chromate salt which was alkylated with Meerwein salt, resulting in the Fischer carbene and a by-product, tetrabutyltin, which proved difficult to remove. Several Fischer carbenes were synthesized and characterized, some simple and known and some novel. In silico work explored the reaction coordinate of the [2+2] cycloaddition towards the formation of β-lactams, and the photoactivation cycle that precedes this process. Computational work also showed the effect of the ligand on the stability and reactivity of the carbene. It was found that in some cases the oxygen on the ligand could negatively influence the stability of the carbene (when compared to a simple methyl carbene). A link between bond orders and back donation in Fischer carbenes was explored in an attempt to theoretically predict the stability of a range of carbenes. , Microsoft� Office Word 2007
- Full Text:
- Date Issued: 2013
An investigation of short-chain fatty acid profiles and influential gastrointenstinal microbiota associated with irritable bowel syndrome
- Authors: Theunissen, Reza
- Date: 2013
- Subjects: Fatty acids in human nutrition , Gastrointestinal system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10352 , http://hdl.handle.net/10948/d1020943
- Description: Microbiota are present in large numbers and as a diverse population within the gastrointestinal tract. There are approximately 400 different species of microbiota which may be beneficial, harmful or both, but each play an important role in the regulation and modulation of the hosts’ bowel processes (McOrist et al. 2008; Dethlefsen et al. 2008). Many of these colon microbiota allow for saccharolytic fermentation of non-digestible dietary fibres and carbohydrates into by-products and intermediates, followed by a subsequent conversion into short chain fatty acids (SCFAs) (mainly n-butyric acid, propionic acid and acetic acid) each of which play an important role in maintaining colon homeostasis (Topping & Clifton 2001). A balance of ‘good’ microbiota (e.g., Bacteroides spp./ Bifidobacteria spp.) and ‘bad’ microbiota (e.g., Veilonellae) and the optimal production of various SCFAs within the gut could possibly allow for proper functioning of the large intestine and assist in decreasing the onset of various colonic disorders such as Irritable Bowel Syndrome (IBS). The sample group for the study consists of male and female patients, with an average age of 40 to 50 years old, whom of which have been diagnosed with either constipation IBS (C-IBS) or diarrhoea IBS (D-IBS) via the Rome III criteria system for IBS diagnosis. DNA and SCFA extractions were optimised for human stool, colonic fluid and tissue biopsy sample obtained from the aforementioned patients. Optimization steps allowed for starting material with high analysis integrity. Different methods of microbiota analysis, such as ARISA, were investigated; however, real-time qPCR was selected as the best method to identify and quantify specific microbiota. Extracted SCFAs were separated via gas chromatography and identified and quantified via Mass Spectrometry. Significant changes in microbial content and SCFA profiles were found to be associated with healthy and IBS patients. Results obtained would however be influenced by external factors typical of clinical studies of this nature. This study allows for opportunities for future research into understanding IBS.
- Full Text:
- Date Issued: 2013
- Authors: Theunissen, Reza
- Date: 2013
- Subjects: Fatty acids in human nutrition , Gastrointestinal system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10352 , http://hdl.handle.net/10948/d1020943
- Description: Microbiota are present in large numbers and as a diverse population within the gastrointestinal tract. There are approximately 400 different species of microbiota which may be beneficial, harmful or both, but each play an important role in the regulation and modulation of the hosts’ bowel processes (McOrist et al. 2008; Dethlefsen et al. 2008). Many of these colon microbiota allow for saccharolytic fermentation of non-digestible dietary fibres and carbohydrates into by-products and intermediates, followed by a subsequent conversion into short chain fatty acids (SCFAs) (mainly n-butyric acid, propionic acid and acetic acid) each of which play an important role in maintaining colon homeostasis (Topping & Clifton 2001). A balance of ‘good’ microbiota (e.g., Bacteroides spp./ Bifidobacteria spp.) and ‘bad’ microbiota (e.g., Veilonellae) and the optimal production of various SCFAs within the gut could possibly allow for proper functioning of the large intestine and assist in decreasing the onset of various colonic disorders such as Irritable Bowel Syndrome (IBS). The sample group for the study consists of male and female patients, with an average age of 40 to 50 years old, whom of which have been diagnosed with either constipation IBS (C-IBS) or diarrhoea IBS (D-IBS) via the Rome III criteria system for IBS diagnosis. DNA and SCFA extractions were optimised for human stool, colonic fluid and tissue biopsy sample obtained from the aforementioned patients. Optimization steps allowed for starting material with high analysis integrity. Different methods of microbiota analysis, such as ARISA, were investigated; however, real-time qPCR was selected as the best method to identify and quantify specific microbiota. Extracted SCFAs were separated via gas chromatography and identified and quantified via Mass Spectrometry. Significant changes in microbial content and SCFA profiles were found to be associated with healthy and IBS patients. Results obtained would however be influenced by external factors typical of clinical studies of this nature. This study allows for opportunities for future research into understanding IBS.
- Full Text:
- Date Issued: 2013
Anchovy and Sardine in Algoa Bay and their relationship with response variables in two threatened avian predators
- Authors: Potter, Cara-Paige
- Date: 2013
- Subjects: Fishes -- Predators of -- South Africa -- Algoa Bay , Anchovies -- South Africa , Sardines -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10730 , http://hdl.handle.net/10948/d1021130
- Description: Huge populations of sardine and anchovy exist in the four major upwelling systems around the world. These fish are both important ecologically and economically. Pelagic fish dominate the mid trophic level and can exert both a top-down control of zooplankton and a bottom-up control on predatory fish and marine top predators. They also make up a substantial contribution of the world catches in seas around the world where they co-exist in upwelling areas. The fluctuations of sardine and anchovy are largely influenced by recruitment from the larval stage and by the physical environmental forces that determine the planktonic compositions upon which they feed. In southern Africa, the biology and behaviour of two threatened seabird species, African penguins (Spheniscus demersus) and Cape gannets (Morus capensis), are directly influenced by the availability of sardine (Sardinops sagax) and anchovy (Engraulis encrasicolus). This study aimed to provide further insight into the fluctuations of sardine and anchovy in relation to the variability of environmental factors such as wind, sea surface temperature, rainfall and plankton abundance, focusing specifically on Algoa Bay in the Eastern Cape, South Africa. Algoa Bay is particularly important as it is home to the world’s largest African penguin colony and the world’s largest gannetry. Therefore, to further investigate the populations of these two seabird species, the fluctuations of their food source were studied.
- Full Text:
- Date Issued: 2013
- Authors: Potter, Cara-Paige
- Date: 2013
- Subjects: Fishes -- Predators of -- South Africa -- Algoa Bay , Anchovies -- South Africa , Sardines -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10730 , http://hdl.handle.net/10948/d1021130
- Description: Huge populations of sardine and anchovy exist in the four major upwelling systems around the world. These fish are both important ecologically and economically. Pelagic fish dominate the mid trophic level and can exert both a top-down control of zooplankton and a bottom-up control on predatory fish and marine top predators. They also make up a substantial contribution of the world catches in seas around the world where they co-exist in upwelling areas. The fluctuations of sardine and anchovy are largely influenced by recruitment from the larval stage and by the physical environmental forces that determine the planktonic compositions upon which they feed. In southern Africa, the biology and behaviour of two threatened seabird species, African penguins (Spheniscus demersus) and Cape gannets (Morus capensis), are directly influenced by the availability of sardine (Sardinops sagax) and anchovy (Engraulis encrasicolus). This study aimed to provide further insight into the fluctuations of sardine and anchovy in relation to the variability of environmental factors such as wind, sea surface temperature, rainfall and plankton abundance, focusing specifically on Algoa Bay in the Eastern Cape, South Africa. Algoa Bay is particularly important as it is home to the world’s largest African penguin colony and the world’s largest gannetry. Therefore, to further investigate the populations of these two seabird species, the fluctuations of their food source were studied.
- Full Text:
- Date Issued: 2013
Cretaceous dyke swarms and brittle deformation structures in the upper continental crust flanking the Atlantic and Indian margins of Southern Africa, and their relationship to Gondwana break-up
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2013
- Subjects: Dikes (Geology) -- Africa, Southern , Joints (Geology) -- Africa, Southern , Gondwana (Continent)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10675 , http://hdl.handle.net/10948/d1020896
- Description: Permanent brittle deformation of rocks of the upper crust is often manifested in the growth of fractures, or sliding along fractures, which may subsequently be intruded by magma and other fluids. The brittle deformation structures described here include faults, joints and dykes. Brittle deformation structures along passive continental margins result from continental fragmentation and related uplift, as is seen around the southern African margins in response to Gondwana break-up. In many cases the fragmentation is accompanied by significant magmatic events, for example the Cretaceous mafic dyke swarms that form major components of the South Atlantic Large Igneous Province (LIP) and originated during the break-up of West Gondwana (Africa and South America). The magmatic events accompanying the break-up of Gondwana resulted in crustal extension and the formation of joint systems and dyke swarms that exhibit distinct geometric features that appear to display fractal patterns. This work analyses the relationship between the Henties Bay-Outjo Dyke Swarm (HOD) on the west coast of Namibia, and the Ponta Grossa Dyke Swarm (PG) on the coast of Brazil, both of which formed ca. ~130 Ma, to test for their co-linearity and fractal geometry before and during West Gondwana break-up. This was achieved by reconstructing Gondwana‘s plates that contained the PG and HOD swarms, using ArcGIS and Gplates software. The dyke analyses was complemented with a comparative study of joints of the Table Mountain Group quartzites (TMG, ca. 400 Ma) in the Western Cape Province and Golden Valley Sill (GVS, ca. 180 Ma) in the Eastern Cape Province, to compare their fractal patterns and possible relationship. Mapping of joints was carried out in the field with the use of a compass and GPS. The HOD trend is positioned largely NNE > NE, but a NW dyke trend is also common. The dominant joints in the TMG trend NNW > WSW and the GVS joints trend WNW > NNE and others. The GVS and HOD orientations appear strongly correlated, while TMG shows no simple orientation correlation with GVS and HOD. The lack of correlation is attributed to the TMG‘s formation in different host-rocks with variable anisotropy and/or the presence of different mechanical processes acting at a different time in geological history. All mapped dykes and joints were analysed to test for fractal geometry. The fractal dimension results of about 18605 HOD dykes from microscopic to mega scale (0.1 mm – 100 km) shows fractal patterns that range between Df = 1.1 to 1.9; and the fractal dimension of about 1716 joints in the TMG and about 1026 joints in the GVS at all scales range between ca. Df = 1.6 to 1.9. The similarity of the fractal patterns indicates that joints and dykes may have formed in response to similar tectonic stress events; and similar orientations may indicate that joints pre-dated the dyke intrusions. However, the data also indicate that dykes are not always related to pre-existing joints.
- Full Text:
- Date Issued: 2013
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2013
- Subjects: Dikes (Geology) -- Africa, Southern , Joints (Geology) -- Africa, Southern , Gondwana (Continent)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10675 , http://hdl.handle.net/10948/d1020896
- Description: Permanent brittle deformation of rocks of the upper crust is often manifested in the growth of fractures, or sliding along fractures, which may subsequently be intruded by magma and other fluids. The brittle deformation structures described here include faults, joints and dykes. Brittle deformation structures along passive continental margins result from continental fragmentation and related uplift, as is seen around the southern African margins in response to Gondwana break-up. In many cases the fragmentation is accompanied by significant magmatic events, for example the Cretaceous mafic dyke swarms that form major components of the South Atlantic Large Igneous Province (LIP) and originated during the break-up of West Gondwana (Africa and South America). The magmatic events accompanying the break-up of Gondwana resulted in crustal extension and the formation of joint systems and dyke swarms that exhibit distinct geometric features that appear to display fractal patterns. This work analyses the relationship between the Henties Bay-Outjo Dyke Swarm (HOD) on the west coast of Namibia, and the Ponta Grossa Dyke Swarm (PG) on the coast of Brazil, both of which formed ca. ~130 Ma, to test for their co-linearity and fractal geometry before and during West Gondwana break-up. This was achieved by reconstructing Gondwana‘s plates that contained the PG and HOD swarms, using ArcGIS and Gplates software. The dyke analyses was complemented with a comparative study of joints of the Table Mountain Group quartzites (TMG, ca. 400 Ma) in the Western Cape Province and Golden Valley Sill (GVS, ca. 180 Ma) in the Eastern Cape Province, to compare their fractal patterns and possible relationship. Mapping of joints was carried out in the field with the use of a compass and GPS. The HOD trend is positioned largely NNE > NE, but a NW dyke trend is also common. The dominant joints in the TMG trend NNW > WSW and the GVS joints trend WNW > NNE and others. The GVS and HOD orientations appear strongly correlated, while TMG shows no simple orientation correlation with GVS and HOD. The lack of correlation is attributed to the TMG‘s formation in different host-rocks with variable anisotropy and/or the presence of different mechanical processes acting at a different time in geological history. All mapped dykes and joints were analysed to test for fractal geometry. The fractal dimension results of about 18605 HOD dykes from microscopic to mega scale (0.1 mm – 100 km) shows fractal patterns that range between Df = 1.1 to 1.9; and the fractal dimension of about 1716 joints in the TMG and about 1026 joints in the GVS at all scales range between ca. Df = 1.6 to 1.9. The similarity of the fractal patterns indicates that joints and dykes may have formed in response to similar tectonic stress events; and similar orientations may indicate that joints pre-dated the dyke intrusions. However, the data also indicate that dykes are not always related to pre-existing joints.
- Full Text:
- Date Issued: 2013
Diet and foraging distribution of gentoo penguins pygoscelis papua at Cow Bay, Falkland Islands
- Authors: Handley, Jonathan Murray
- Date: 2013
- Subjects: Gentoo penguin -- Food -- Falkland Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10724 , http://hdl.handle.net/10948/d1020377
- Description: Knowledge of diet and distribution in marine top predators is critical in interpreting their ecological role. Furthermore, this information is required for effective management and conservation of these species. For gentoo penguins at the Falkland Islands a previous overlap in dietary items with commercial fisheries was recognised. Despite this the at-sea distribution has been poorly studied and only at a few localities. Therefore, this thesis looks to broaden the knowledge of foraging ecology for gentoo penguins at another site in the archipelago, Cow Bay. The aim was firstly, through stomach content analysis, to determine if diet changed over a large temporal scale (2002/03/04 – 2011/12/13), and between the chick guard and crèche periods of chick rearing. Secondly, through GPS loggers, to assess distribution at sea during the incubation and chick guard periods (2012/13). Additionally, foraging ecology between genders was investigated. Gentoo penguins at Cow Bay foraged primarily on fish (66-99 percent) throughout the entire study period. The principle prey item by mass was Patagonotothen spp., considered previously as discard by fisheries but now an important commercial resource, for all periods (47-78 percent) except that of the 2012/13 crèche period (19 percent). During this period Sprattus fugensis made up the bulk of the diet (52 percent). Cephalopods, particularly Loligo gahi (1-24 percent), were also prominent in the diet and crustaceans contributed negligibly. The diet indicated that gentoo penguins are capable of both a benthic and pelagic feeding strategy which likely reflects changes in local prey abundance. Birds typically conducted foraging activities during daylight hours with greater trip duration, path length, maximum distance and area utilised during the incubation period than the guard. All trips were confined to the continental shelf and within the boundaries of a marine management zone, the Falkland Islands Interim Conservation Zone (FICZ). Males and females fed on the same size and composition of prey items. Trip duration, path length and maximum distance from the colony were not significantly different, although males foraged in a slightly larger area than females marginally to the north. As at-sea distribution was confined within the FICZ this management area provides protection to food resources of gentoo penguins breeding at Cow Bay. At this site, the population is increasing, likely associated with increased prey availability as evidenced by record catches of Patagonotothen spp. in recent years at the Falkland Islands. Continued long term monitoring of gentoo penguin diet and fishery yields to allow detection of possible competition in the future is recommended. As marine sentinels, on-going monitoring of gentoo penguin populations at the Falkland Islands is likely to provide early warning signs of reduced prey availability.
- Full Text:
- Date Issued: 2013
- Authors: Handley, Jonathan Murray
- Date: 2013
- Subjects: Gentoo penguin -- Food -- Falkland Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10724 , http://hdl.handle.net/10948/d1020377
- Description: Knowledge of diet and distribution in marine top predators is critical in interpreting their ecological role. Furthermore, this information is required for effective management and conservation of these species. For gentoo penguins at the Falkland Islands a previous overlap in dietary items with commercial fisheries was recognised. Despite this the at-sea distribution has been poorly studied and only at a few localities. Therefore, this thesis looks to broaden the knowledge of foraging ecology for gentoo penguins at another site in the archipelago, Cow Bay. The aim was firstly, through stomach content analysis, to determine if diet changed over a large temporal scale (2002/03/04 – 2011/12/13), and between the chick guard and crèche periods of chick rearing. Secondly, through GPS loggers, to assess distribution at sea during the incubation and chick guard periods (2012/13). Additionally, foraging ecology between genders was investigated. Gentoo penguins at Cow Bay foraged primarily on fish (66-99 percent) throughout the entire study period. The principle prey item by mass was Patagonotothen spp., considered previously as discard by fisheries but now an important commercial resource, for all periods (47-78 percent) except that of the 2012/13 crèche period (19 percent). During this period Sprattus fugensis made up the bulk of the diet (52 percent). Cephalopods, particularly Loligo gahi (1-24 percent), were also prominent in the diet and crustaceans contributed negligibly. The diet indicated that gentoo penguins are capable of both a benthic and pelagic feeding strategy which likely reflects changes in local prey abundance. Birds typically conducted foraging activities during daylight hours with greater trip duration, path length, maximum distance and area utilised during the incubation period than the guard. All trips were confined to the continental shelf and within the boundaries of a marine management zone, the Falkland Islands Interim Conservation Zone (FICZ). Males and females fed on the same size and composition of prey items. Trip duration, path length and maximum distance from the colony were not significantly different, although males foraged in a slightly larger area than females marginally to the north. As at-sea distribution was confined within the FICZ this management area provides protection to food resources of gentoo penguins breeding at Cow Bay. At this site, the population is increasing, likely associated with increased prey availability as evidenced by record catches of Patagonotothen spp. in recent years at the Falkland Islands. Continued long term monitoring of gentoo penguin diet and fishery yields to allow detection of possible competition in the future is recommended. As marine sentinels, on-going monitoring of gentoo penguin populations at the Falkland Islands is likely to provide early warning signs of reduced prey availability.
- Full Text:
- Date Issued: 2013
Evaluating the training and supply of artisans in the South African construction industry
- Authors: Anugwo, Iruka Chijindu
- Date: 2013
- Subjects: Skilled labor -- South Africa , Skilled labor -- Training -- South Africa , Artisans -- South Africa , Construction industry -- Employees --Training of -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9672 , http://hdl.handle.net/10948/d1020042
- Description: The study focused on identifying ways in which to improve and increase the quality of training and supply of skilled artisans in the South African construction industry (especially in Gauteng Province) in terms of short and medium term approach. The construction industry is facing a severe skills crisis and this has made it so difficult to recruit competent artisans. This may be as a result of artisans being regarded as the lowest in the hierarchy of construction worker positions. In addition, these artisans warrant less training than those at executive- and managerial levels. This negative attitude towards artisans training has plunged the industry into crisis. Those involved find it difficult to successfully complete projects on time, within budgeted project costs and within the required quality specification due to lack of competent artisans. However, serious attention is required towards enhancing artisan training in the industry. It is imperative and vital to ensure the survival of the industry. The cardinal aim of this research project was to demonstrate a guiding solution towards the skills crisis. Thus, in order to initiate a tremendous change in the skills profile, certain measures are required, e.g. expanding training institutions to local regions; upgrading and aligning facilities in the training institutions to industrial demands and the dissemination of vital information that will ensure the attractiveness of the industry. This will safeguard the construction organisations operating in Gauteng Province. Although the industry is a major player in the economy, there is need for special attention in order to ensure sustainable growth and economic development. The Government, construction industry stakeholders and training institutions personnel should collaborate to salvage the skills crisis by strategically developing programmes (in accordance with industrial requirements) that will benefit prospective learners. The researcher adopted the descriptive- and analytical survey method, which entailed the use of questionnaires and a review of the related literature for gathering relevant data. The methodology used in the research was the quantitative data analysis. The feature findings of the research concluded that the skilled artisans profile is insufficient to meet industry demands. In addition, training institutions and primary- and secondary educational systems are characterized by ninadequacy and incompetency to produce skilled artisans. The situation is exacerbated by the lack of harmonization between the training institutions and the vindustry’s requirements. Furthermore, the majority of the respondents acknowledged that training of their workers is an important aspect to them, but few of these organisations indicated that they make use of formal training institutions such as FET colleges. The recommendation include that all the stakeholders in the construction industry should form collaborations to strategically develop programmes that would upgrade the existing training institutions. This could be done through provision of adequate funds and resources and the dissemination of vital information that is capable to promote the attractiveness of the industry image.
- Full Text:
- Date Issued: 2013
- Authors: Anugwo, Iruka Chijindu
- Date: 2013
- Subjects: Skilled labor -- South Africa , Skilled labor -- Training -- South Africa , Artisans -- South Africa , Construction industry -- Employees --Training of -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9672 , http://hdl.handle.net/10948/d1020042
- Description: The study focused on identifying ways in which to improve and increase the quality of training and supply of skilled artisans in the South African construction industry (especially in Gauteng Province) in terms of short and medium term approach. The construction industry is facing a severe skills crisis and this has made it so difficult to recruit competent artisans. This may be as a result of artisans being regarded as the lowest in the hierarchy of construction worker positions. In addition, these artisans warrant less training than those at executive- and managerial levels. This negative attitude towards artisans training has plunged the industry into crisis. Those involved find it difficult to successfully complete projects on time, within budgeted project costs and within the required quality specification due to lack of competent artisans. However, serious attention is required towards enhancing artisan training in the industry. It is imperative and vital to ensure the survival of the industry. The cardinal aim of this research project was to demonstrate a guiding solution towards the skills crisis. Thus, in order to initiate a tremendous change in the skills profile, certain measures are required, e.g. expanding training institutions to local regions; upgrading and aligning facilities in the training institutions to industrial demands and the dissemination of vital information that will ensure the attractiveness of the industry. This will safeguard the construction organisations operating in Gauteng Province. Although the industry is a major player in the economy, there is need for special attention in order to ensure sustainable growth and economic development. The Government, construction industry stakeholders and training institutions personnel should collaborate to salvage the skills crisis by strategically developing programmes (in accordance with industrial requirements) that will benefit prospective learners. The researcher adopted the descriptive- and analytical survey method, which entailed the use of questionnaires and a review of the related literature for gathering relevant data. The methodology used in the research was the quantitative data analysis. The feature findings of the research concluded that the skilled artisans profile is insufficient to meet industry demands. In addition, training institutions and primary- and secondary educational systems are characterized by ninadequacy and incompetency to produce skilled artisans. The situation is exacerbated by the lack of harmonization between the training institutions and the vindustry’s requirements. Furthermore, the majority of the respondents acknowledged that training of their workers is an important aspect to them, but few of these organisations indicated that they make use of formal training institutions such as FET colleges. The recommendation include that all the stakeholders in the construction industry should form collaborations to strategically develop programmes that would upgrade the existing training institutions. This could be done through provision of adequate funds and resources and the dissemination of vital information that is capable to promote the attractiveness of the industry image.
- Full Text:
- Date Issued: 2013
Evaluation of the performance of community-based natural resources management (CBNRM) projects along an aridity gradient in Botswana
- Authors: Mpofu, Khulekani
- Date: 2013
- Subjects: Community-Based Natural Resource Management in Southern Africa (Project) , Natural resources, Communal -- Botswana , Natural resources -- Management -- Botswana , Natural resources -- Management -- Economic aspects -- Botswana , Conservation of natural resources -- Botswana , Conservation of natural resources -- Economic aspects -- Botswana , Arid regions -- Botswana , Natural resources -- Management -- Citizen participation -- Botswana
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4740 , http://hdl.handle.net/10962/d1006063 , Community-Based Natural Resource Management in Southern Africa (Project) , Natural resources, Communal -- Botswana , Natural resources -- Management -- Botswana , Natural resources -- Management -- Economic aspects -- Botswana , Conservation of natural resources -- Botswana , Conservation of natural resources -- Economic aspects -- Botswana , Arid regions -- Botswana , Natural resources -- Management -- Citizen participation -- Botswana
- Description: The Botswana Community Based Natural Resources Management (CBNRM) programme started in 1989. Its aims were to promote sustainable development through sustainable natural resources management and utilisation to improve rural livelihoods. The country CBNRM programme has recorded mixed outcomes and this has raised questions on the programme performance throughout the country. Since the programme has been recognised as one of the eight main livelihood strategies for rural communities in Botswana, there was a need to evaluate the programme performance and determine the factors that influence it. This thesis therefore evaluated the performance of CBNRM projects along an aridity gradient in Botswana and by so doing answered the two research questions of: (1) What factors influence the performance of CBNRM? And (2) how does aridity influence the performance of CBNRM programmes? Performance was determined in terms of financial benefits generated by CBNRM projects and the projects adherence to the CBNRM principles. Data were collected from seven selected CBNRM projects covering three aridity zones (wet, medium rainfall and dry areas) in the country. Data were also collected from key informants and community based organisations (CBO) project managers. Research findings have indicated differences in the performance of CBNRM projects across the identified three aridity zones. Factors that influenced the performance of CBNRM projects varied among the three aridity zones. These factors included: existence of complimentary rules and regulations for managing CBNRM projects; literacy levels of communities involved in CBNRM; ethnic composition of the project communities; historic and current socio-economic trends within communities; collaboration between CBNRM institutions and other local level institutes; amount of benefits generated through the projects; ability of institutions to resolve outstanding issues in time and type of CBNRM project. Research results also indicated that there was variation in the performance of CBNRM projects across the three aridity zones. Aridity was found to directly influence the performance of CBNRM projects through its influence on the amount of revenues that projects generated.
- Full Text:
- Date Issued: 2013
- Authors: Mpofu, Khulekani
- Date: 2013
- Subjects: Community-Based Natural Resource Management in Southern Africa (Project) , Natural resources, Communal -- Botswana , Natural resources -- Management -- Botswana , Natural resources -- Management -- Economic aspects -- Botswana , Conservation of natural resources -- Botswana , Conservation of natural resources -- Economic aspects -- Botswana , Arid regions -- Botswana , Natural resources -- Management -- Citizen participation -- Botswana
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4740 , http://hdl.handle.net/10962/d1006063 , Community-Based Natural Resource Management in Southern Africa (Project) , Natural resources, Communal -- Botswana , Natural resources -- Management -- Botswana , Natural resources -- Management -- Economic aspects -- Botswana , Conservation of natural resources -- Botswana , Conservation of natural resources -- Economic aspects -- Botswana , Arid regions -- Botswana , Natural resources -- Management -- Citizen participation -- Botswana
- Description: The Botswana Community Based Natural Resources Management (CBNRM) programme started in 1989. Its aims were to promote sustainable development through sustainable natural resources management and utilisation to improve rural livelihoods. The country CBNRM programme has recorded mixed outcomes and this has raised questions on the programme performance throughout the country. Since the programme has been recognised as one of the eight main livelihood strategies for rural communities in Botswana, there was a need to evaluate the programme performance and determine the factors that influence it. This thesis therefore evaluated the performance of CBNRM projects along an aridity gradient in Botswana and by so doing answered the two research questions of: (1) What factors influence the performance of CBNRM? And (2) how does aridity influence the performance of CBNRM programmes? Performance was determined in terms of financial benefits generated by CBNRM projects and the projects adherence to the CBNRM principles. Data were collected from seven selected CBNRM projects covering three aridity zones (wet, medium rainfall and dry areas) in the country. Data were also collected from key informants and community based organisations (CBO) project managers. Research findings have indicated differences in the performance of CBNRM projects across the identified three aridity zones. Factors that influenced the performance of CBNRM projects varied among the three aridity zones. These factors included: existence of complimentary rules and regulations for managing CBNRM projects; literacy levels of communities involved in CBNRM; ethnic composition of the project communities; historic and current socio-economic trends within communities; collaboration between CBNRM institutions and other local level institutes; amount of benefits generated through the projects; ability of institutions to resolve outstanding issues in time and type of CBNRM project. Research results also indicated that there was variation in the performance of CBNRM projects across the three aridity zones. Aridity was found to directly influence the performance of CBNRM projects through its influence on the amount of revenues that projects generated.
- Full Text:
- Date Issued: 2013
Fish and fisheries of Bangweulu wetlands, Zambia
- Huchzermeyer, Carl Friedrich
- Authors: Huchzermeyer, Carl Friedrich
- Date: 2013
- Subjects: Bangweulu Swamps (Zambia) , Fisheries -- Zambia -- Bangweulu Swamps , Fishes -- Zambia -- Bangweulu Swamps , Fishery management -- Zambia -- Bangweulu Swamps , Fishing -- Zambia -- Bangweulu Swamps , Fishing -- Economic aspects -- Zambia -- Bangweulu Swamps , Fish stock assessment -- Zambia -- Bangweulu Swamps , Fish as food -- Zambia -- Bangweulu Swamps , Conservation of natural resources -- Zambia -- Bangweulu Swamps , Sustainable development -- Zambia -- Bangweulu Swamps
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5203 , http://hdl.handle.net/10962/d1003927 , Bangweulu Swamps (Zambia) , Fisheries -- Zambia -- Bangweulu Swamps , Fishes -- Zambia -- Bangweulu Swamps , Fishery management -- Zambia -- Bangweulu Swamps , Fishing -- Zambia -- Bangweulu Swamps , Fishing -- Economic aspects -- Zambia -- Bangweulu Swamps , Fish stock assessment -- Zambia -- Bangweulu Swamps , Fish as food -- Zambia -- Bangweulu Swamps , Conservation of natural resources -- Zambia -- Bangweulu Swamps , Sustainable development -- Zambia -- Bangweulu Swamps
- Description: Bangweulu Wetlands is a 6000 km² public-private-partnership conservation area in northeastern Zambia, lying on the south-eastern margins of the Bangweulu Swamps, Congo River system. The area is important for wildlife conservation, tourism and as a fishing ground for the local inhabitants. This study provides a baseline of the fish and fisheries of this area. The conservation area is situated on the transition zone between woodland, floodplain and swamp. A total of 42 fish species representing 12 taxonomic families were collected. The fish fauna of the area was characterised by a diversity of small cyprinids (14 species), cichlids (9 species), clariid catfishes (4 species) and mormyrids (4 species). Species such as Clarias gariepinus, C. ngamensis, Marcusenius macrolepidotus, Tilapia rendali, T. sparrmanii and several small Barbus species were shared with adjacent floodplain systems such as the upper Zambezi and Kafue rivers. Fishing was undertaken by fishing groups consisting of a fisherman and his family, or a group of men fishing together. Access to the fishing grounds was controlled by traditional fishing leaders, who collected tribute from fishermen. Fishing groups utilised fixed, distinct fishing areas determined by ancestry. The most important time for fishing was during the drawdown phase of the floodplains, from March until June. During the dry season fewer groups were engaged in fishing, with many having returned to farming activities. The main fishing methods of the floodplain fishery were basket traps and mosquito-mesh funnel nets set into earth fish barriers (fish weirs) constructed on the plains, various mesh sizes of gillnets, hook longlines and seine nets. The use of fish spears, drag baskets and piscicides was of lesser importance. Most fishing gears were constructed of a variety of natural and modern, manufactured materials. The fishery was multi-species and 23 fish species were recorded from in catch. The three most important species in the catches were C. gariepinus, T. rendalli and M. macrolepidotus. Together these contributed 67% by weight to the catch. Catch-per-unit-effort (CPUE) for the different gears was 0.4 ± 0.3 kg.trap.night⁻¹ for basket traps, 2.7 ± 4.6 kg.net.night⁻¹ for funnel nets, 0.3 ± 0.5 kg.50 m net.night⁻¹ for gill nets, 3.5 ± 6.3 kg.100 hooks.night⁻¹ for longlines, 1.79 ± 1.11 kg.haul⁻¹ for mosquito-mesh seine nets and 6.87 ± 6.27 kg.haul⁻¹ for larger-mesh seine nets. The weight of average daily landings of fishing groups, using a variety of gears was 7.8 ± 7.4 kg. Fishermen were able to maintain the same catch rate between dry and wet seasons, with no significant differences (p < 0.05) in daily landings between seasons. Yield per fisherman for a seven month season, which required 2-3 relocations due to falling water level, was 1.64 t based on catch assessment, and 1.9 t from a socio-economic survey. A tentative yield per area estimate for the area was 2I7 kg.ha⁻¹ over the three month shallow-floodplain fishing season. Most fish landed in the fishery were processed into sundried or smoke-dried products. These were used for 1) home consumption, 2) trade with village farmers (from up to 70 km inland of the fishing grounds) in exchange for staple starch meal, and 3) sold to urban fish traders, reaching markets as distant as Lubumbashi in Democratic Republic of Congo. Fish traders toured fishing camps to buy fish, supporting auxiliary industries such as transport and accommodation services. The price for dried fish at source was 3.14 ± 1.34 USDlkg and the market price reported for the Zambian Copperbelt was 6.14 ± 2.54 USD/kg. Typical returns on investment in fish trading were estimated as 68-77%. The fishery was considered to be biologically and socially sustainable. By harvesting a seasonally transient assemblage of species with high productivity and biological turnover rates and with life histories adapted to high mortality, fishermen were able to maintain a stable and viable livelihood. Management recommendations for the area were that a fisheries management plan be developed that would seek to strengthen the traditional system of rights-allocation, address problems between fishing and tourism activities, and enhance communication between fisheries and conservation stakeholders. To do this it was recommended that: 1) conservation authorities recognise the importance of the fishery, 2) no changes to current effort levels and fishing methods were necessary, 3) points 1 and 2 above be used to improve communication and trust between conservation authorities and fishermen, 4) customary resource-access mechanisms be understood and strengthened so that local inhabitants' rights to the resource are protected, 5) fishermen help formulate and accept conservation and tourism rules, 6) tourists and guides be made aware of the function of the fishery, 7) a fisheries management forum of key community, government and conservation stakeholders be formed to shape and implement the fisheries management plan, 8) locally-adapted bylaws be created to legitimise crucial floodplain gears currently considered illegal (e.g. mosquito-net gears, fish weirs), 9) no intervention to formalise fish trading be made, and 10) a trained person with a fisheries background be hired oversee the implementation of the recommendations.
- Full Text:
- Date Issued: 2013
- Authors: Huchzermeyer, Carl Friedrich
- Date: 2013
- Subjects: Bangweulu Swamps (Zambia) , Fisheries -- Zambia -- Bangweulu Swamps , Fishes -- Zambia -- Bangweulu Swamps , Fishery management -- Zambia -- Bangweulu Swamps , Fishing -- Zambia -- Bangweulu Swamps , Fishing -- Economic aspects -- Zambia -- Bangweulu Swamps , Fish stock assessment -- Zambia -- Bangweulu Swamps , Fish as food -- Zambia -- Bangweulu Swamps , Conservation of natural resources -- Zambia -- Bangweulu Swamps , Sustainable development -- Zambia -- Bangweulu Swamps
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5203 , http://hdl.handle.net/10962/d1003927 , Bangweulu Swamps (Zambia) , Fisheries -- Zambia -- Bangweulu Swamps , Fishes -- Zambia -- Bangweulu Swamps , Fishery management -- Zambia -- Bangweulu Swamps , Fishing -- Zambia -- Bangweulu Swamps , Fishing -- Economic aspects -- Zambia -- Bangweulu Swamps , Fish stock assessment -- Zambia -- Bangweulu Swamps , Fish as food -- Zambia -- Bangweulu Swamps , Conservation of natural resources -- Zambia -- Bangweulu Swamps , Sustainable development -- Zambia -- Bangweulu Swamps
- Description: Bangweulu Wetlands is a 6000 km² public-private-partnership conservation area in northeastern Zambia, lying on the south-eastern margins of the Bangweulu Swamps, Congo River system. The area is important for wildlife conservation, tourism and as a fishing ground for the local inhabitants. This study provides a baseline of the fish and fisheries of this area. The conservation area is situated on the transition zone between woodland, floodplain and swamp. A total of 42 fish species representing 12 taxonomic families were collected. The fish fauna of the area was characterised by a diversity of small cyprinids (14 species), cichlids (9 species), clariid catfishes (4 species) and mormyrids (4 species). Species such as Clarias gariepinus, C. ngamensis, Marcusenius macrolepidotus, Tilapia rendali, T. sparrmanii and several small Barbus species were shared with adjacent floodplain systems such as the upper Zambezi and Kafue rivers. Fishing was undertaken by fishing groups consisting of a fisherman and his family, or a group of men fishing together. Access to the fishing grounds was controlled by traditional fishing leaders, who collected tribute from fishermen. Fishing groups utilised fixed, distinct fishing areas determined by ancestry. The most important time for fishing was during the drawdown phase of the floodplains, from March until June. During the dry season fewer groups were engaged in fishing, with many having returned to farming activities. The main fishing methods of the floodplain fishery were basket traps and mosquito-mesh funnel nets set into earth fish barriers (fish weirs) constructed on the plains, various mesh sizes of gillnets, hook longlines and seine nets. The use of fish spears, drag baskets and piscicides was of lesser importance. Most fishing gears were constructed of a variety of natural and modern, manufactured materials. The fishery was multi-species and 23 fish species were recorded from in catch. The three most important species in the catches were C. gariepinus, T. rendalli and M. macrolepidotus. Together these contributed 67% by weight to the catch. Catch-per-unit-effort (CPUE) for the different gears was 0.4 ± 0.3 kg.trap.night⁻¹ for basket traps, 2.7 ± 4.6 kg.net.night⁻¹ for funnel nets, 0.3 ± 0.5 kg.50 m net.night⁻¹ for gill nets, 3.5 ± 6.3 kg.100 hooks.night⁻¹ for longlines, 1.79 ± 1.11 kg.haul⁻¹ for mosquito-mesh seine nets and 6.87 ± 6.27 kg.haul⁻¹ for larger-mesh seine nets. The weight of average daily landings of fishing groups, using a variety of gears was 7.8 ± 7.4 kg. Fishermen were able to maintain the same catch rate between dry and wet seasons, with no significant differences (p < 0.05) in daily landings between seasons. Yield per fisherman for a seven month season, which required 2-3 relocations due to falling water level, was 1.64 t based on catch assessment, and 1.9 t from a socio-economic survey. A tentative yield per area estimate for the area was 2I7 kg.ha⁻¹ over the three month shallow-floodplain fishing season. Most fish landed in the fishery were processed into sundried or smoke-dried products. These were used for 1) home consumption, 2) trade with village farmers (from up to 70 km inland of the fishing grounds) in exchange for staple starch meal, and 3) sold to urban fish traders, reaching markets as distant as Lubumbashi in Democratic Republic of Congo. Fish traders toured fishing camps to buy fish, supporting auxiliary industries such as transport and accommodation services. The price for dried fish at source was 3.14 ± 1.34 USDlkg and the market price reported for the Zambian Copperbelt was 6.14 ± 2.54 USD/kg. Typical returns on investment in fish trading were estimated as 68-77%. The fishery was considered to be biologically and socially sustainable. By harvesting a seasonally transient assemblage of species with high productivity and biological turnover rates and with life histories adapted to high mortality, fishermen were able to maintain a stable and viable livelihood. Management recommendations for the area were that a fisheries management plan be developed that would seek to strengthen the traditional system of rights-allocation, address problems between fishing and tourism activities, and enhance communication between fisheries and conservation stakeholders. To do this it was recommended that: 1) conservation authorities recognise the importance of the fishery, 2) no changes to current effort levels and fishing methods were necessary, 3) points 1 and 2 above be used to improve communication and trust between conservation authorities and fishermen, 4) customary resource-access mechanisms be understood and strengthened so that local inhabitants' rights to the resource are protected, 5) fishermen help formulate and accept conservation and tourism rules, 6) tourists and guides be made aware of the function of the fishery, 7) a fisheries management forum of key community, government and conservation stakeholders be formed to shape and implement the fisheries management plan, 8) locally-adapted bylaws be created to legitimise crucial floodplain gears currently considered illegal (e.g. mosquito-net gears, fish weirs), 9) no intervention to formalise fish trading be made, and 10) a trained person with a fisheries background be hired oversee the implementation of the recommendations.
- Full Text:
- Date Issued: 2013
Foraging ecology of Cape Gannets (Morus Capensis) at Bird Island, Algoa Bay
- Authors: Green, David Bruce
- Date: 2013
- Subjects: Birds of prey -- Behavior -- South Africa -- Algoa Bay , Gannets -- South Africa -- Algoa Bay , Birds -- Breeding -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10725 , http://hdl.handle.net/10948/d1020790
- Description: The Cape gannet has undergone considerable population change and redistribution over the past 50 years. This has been linked to shifts in the abundance and distribution of their dominant prey, sardine and anchovy. Five breeding colonies, along the west coast of Southern Africa, have shown rapid population declines as a result of reduced prey availability. In contrast, a single colony (Bird Island, Algoa Bay) on the south coast of South Africa has, over the same period, grown fivefold and now supports approximately two thirds of the total population. Due to its conservation importance, and isolation from other breeding localities, it is important to assess the health of the Bird Island colony, and determine how foraging distribution relates to the environment to evaluate current measures of protection. This was achieved through two related studies; a long-term dietary analysis spanning 34 years, and a spatial foraging study, which related three years of tracking data to estimates of prey availability, oceanographic features and marine protected areas (MPAs). The results of the dietary study showed that the dietary constituents of Cape gannets breeding at Bird Island have remained similar over the last three decades, but the importance of sardine and anchovy has increased significantly. For sardine, in particular, this reflects an increased availability of this species (as deduced from hydroacoustic surveys) within the foraging range of the Bird Island colony. The dietary abundance of anchovy was found to be negatively correlated with that of sardine. Surprisingly,.the dietary abundance of anchovy was also negatively correlated with estimates of its availability based on acoustic surveys. The latter is likely to be due to sardine being a preferred prey item. Recent decreases in the dietary contribution of sardine (since 2005) suggest that this species is becoming less available to gannets, with profound implications in terms of nutrient gain associated with foraging. However, this has been mediated by an increase in the dietary contribution of anchovy, which now accounts for the vast majority of prey taken. Spatially, the foraging range of the Bird Island colony expanded during the three years of study, indicating an increase in effort. This increase was likely in an effort to track a distributional change of sardine and anchovy, which showed an apparent westward shift during the study period. There was, however, no evidence of birds tracking features associated with high productivity. This may have been partly due to anomalously warm conditions during the summer of 2012/2013, in which an absence of coastal upwelling prevented surface cooling. Nonetheless, low sea surface temperatures and high chlorophyll a concentrations do not seem to be reliable indicators of important Cape gannet foragingareas. Foraging effort was largely concentrated outside of MPAs, indicating that the current MPA network provides little protection for foraging gannets. This could change with the additional protection of the proposed Greater Addo Elephant National Park MPA expansion, as prey species are allowed to recover following the removal of fishing pressure. Overall, the colony appears to be in good condition as the diet is still dominated by live prey items, and the foraging range remains smaller than many of the colonies along the west coast. However, it is important that monitoring be continued, in particular with respect to changes in the availability of sardine and anchovy. Long-term shifts of these species out of the colony‘s foraging range could negatively influence the population in the future. This might be worsened by interspecific competition for prey resources. Considering the conservation importance of this population, maintenance of healthy prey stocks within the home range of breeding Cape gannets should be prioritised in order to prevent declines similar to those observed at west coast colonies.
- Full Text:
- Date Issued: 2013
- Authors: Green, David Bruce
- Date: 2013
- Subjects: Birds of prey -- Behavior -- South Africa -- Algoa Bay , Gannets -- South Africa -- Algoa Bay , Birds -- Breeding -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10725 , http://hdl.handle.net/10948/d1020790
- Description: The Cape gannet has undergone considerable population change and redistribution over the past 50 years. This has been linked to shifts in the abundance and distribution of their dominant prey, sardine and anchovy. Five breeding colonies, along the west coast of Southern Africa, have shown rapid population declines as a result of reduced prey availability. In contrast, a single colony (Bird Island, Algoa Bay) on the south coast of South Africa has, over the same period, grown fivefold and now supports approximately two thirds of the total population. Due to its conservation importance, and isolation from other breeding localities, it is important to assess the health of the Bird Island colony, and determine how foraging distribution relates to the environment to evaluate current measures of protection. This was achieved through two related studies; a long-term dietary analysis spanning 34 years, and a spatial foraging study, which related three years of tracking data to estimates of prey availability, oceanographic features and marine protected areas (MPAs). The results of the dietary study showed that the dietary constituents of Cape gannets breeding at Bird Island have remained similar over the last three decades, but the importance of sardine and anchovy has increased significantly. For sardine, in particular, this reflects an increased availability of this species (as deduced from hydroacoustic surveys) within the foraging range of the Bird Island colony. The dietary abundance of anchovy was found to be negatively correlated with that of sardine. Surprisingly,.the dietary abundance of anchovy was also negatively correlated with estimates of its availability based on acoustic surveys. The latter is likely to be due to sardine being a preferred prey item. Recent decreases in the dietary contribution of sardine (since 2005) suggest that this species is becoming less available to gannets, with profound implications in terms of nutrient gain associated with foraging. However, this has been mediated by an increase in the dietary contribution of anchovy, which now accounts for the vast majority of prey taken. Spatially, the foraging range of the Bird Island colony expanded during the three years of study, indicating an increase in effort. This increase was likely in an effort to track a distributional change of sardine and anchovy, which showed an apparent westward shift during the study period. There was, however, no evidence of birds tracking features associated with high productivity. This may have been partly due to anomalously warm conditions during the summer of 2012/2013, in which an absence of coastal upwelling prevented surface cooling. Nonetheless, low sea surface temperatures and high chlorophyll a concentrations do not seem to be reliable indicators of important Cape gannet foragingareas. Foraging effort was largely concentrated outside of MPAs, indicating that the current MPA network provides little protection for foraging gannets. This could change with the additional protection of the proposed Greater Addo Elephant National Park MPA expansion, as prey species are allowed to recover following the removal of fishing pressure. Overall, the colony appears to be in good condition as the diet is still dominated by live prey items, and the foraging range remains smaller than many of the colonies along the west coast. However, it is important that monitoring be continued, in particular with respect to changes in the availability of sardine and anchovy. Long-term shifts of these species out of the colony‘s foraging range could negatively influence the population in the future. This might be worsened by interspecific competition for prey resources. Considering the conservation importance of this population, maintenance of healthy prey stocks within the home range of breeding Cape gannets should be prioritised in order to prevent declines similar to those observed at west coast colonies.
- Full Text:
- Date Issued: 2013
Influence of predicted sea-level rise on the salt marsh of the Swartkops, Kromme and Knysna estuaries
- Authors: Schmidt, Jadon
- Date: 2013
- Subjects: Sea-level -- South Africa , Salt marshes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3765 , vital:20462
- Description: Salt marshes are coastal wetlands that are highly productive and biologically diverse ecosystems. These systems are under threat from rising sea levels which are predicted to accelerate in the future. Salt marsh habitats of the Swartkops, Kromme and Knysna estuaries were examined to determine their structure along an elevation gradient and how this structure has changed over the past six decades, what the primary drivers of this structure were and whether the salt marsh surface is stable, rising or declining relative to predicted sea level rise. During this study the following main hypothesis was tested: The environmental drivers of salt marsh zonation are elevation above mean sea level (AMSL), soil moisture and soil salinity, all of which will be impacted by the predicted rise in sea level of 1.48 mm.y-1, unless the salt marshes are able to accrete at a rate such that surface elevation gain is sufficient to offset the rate of sea level rise. The results showed that the salt marsh vegetation structure followed a predictable pattern down the elevation gradient with distinct supratidal, intertidal and subtidal habitats identified for each estuary. These three zones occurred between elevations around Mean Sea Level of -0.86 to 2.42 AMSL for Swartkops, -0.3 to 2.95 m AMSL for Kromme and -0.48 to 3.14 m AMSL for Knysna. A floodplain component was also identified in the Swartkops estuary, which was restricted to the upper reaches. During the last 60 years, losses of intertidal and supratidal salt marsh for Swartkops were 74.31 ha and 30.23 ha respectively, 17.01 ha of intertidal and supratidal salt marsh was lost in Kromme while intertidal salt marsh in Knysna has diminished by 168 ha. These losses were mainly attributed to developmental pressure, although there are indications that rising sea levels are becoming more influential in the lower reaches. The main environmental drivers for salt marsh structure in the Swartkops were shown to be soil moisture content and elevation, soil moisture and organic content for Kromme while elevation and soil redox potential were dominant in Knysna. In a comparison of all three systems, soil moisture content and redox potential were found to be the most important drivers of vegetation distribution. Elevation dictates tidal inundation periodicity and frequency, and thus acts to influence all edaphic factors driving vegetation distribution. Results indicated that the salt marsh surface elevation of the lower and middle sections of the Swartkops, Kromme and Knysna estuaries are generally declining relative to current sea level rise. Where increases in surface elevation (relative to current sea level rise) were recorded, the majority of the accretion occurred after episodic flooding in winter 2011. These increases typically occurred in the upper reaches and were attributed to the deposition of fluvial sediments as a result of these floods. Results for Knysna indicate that while a majority of the salt marsh surface is accreting vertically, only three areas are increasing their elevation at a rate at least equal to current sea level rise. In these areas, developmental pressures will prevent a landward transgression of the salt marsh, forming an artificial “coastal squeeze”. Geomorphological limitations (steep hills adjacent to the salt marsh) will prevent any transgression in the upper reaches of the Kromme Estuary. Supratidal habitat in the upper reaches of the Swartkops estuary, if undeveloped, will provide the only viable habitat for the salt marsh to migrate into, given sufficient surface elevation.
- Full Text:
- Date Issued: 2013
- Authors: Schmidt, Jadon
- Date: 2013
- Subjects: Sea-level -- South Africa , Salt marshes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3765 , vital:20462
- Description: Salt marshes are coastal wetlands that are highly productive and biologically diverse ecosystems. These systems are under threat from rising sea levels which are predicted to accelerate in the future. Salt marsh habitats of the Swartkops, Kromme and Knysna estuaries were examined to determine their structure along an elevation gradient and how this structure has changed over the past six decades, what the primary drivers of this structure were and whether the salt marsh surface is stable, rising or declining relative to predicted sea level rise. During this study the following main hypothesis was tested: The environmental drivers of salt marsh zonation are elevation above mean sea level (AMSL), soil moisture and soil salinity, all of which will be impacted by the predicted rise in sea level of 1.48 mm.y-1, unless the salt marshes are able to accrete at a rate such that surface elevation gain is sufficient to offset the rate of sea level rise. The results showed that the salt marsh vegetation structure followed a predictable pattern down the elevation gradient with distinct supratidal, intertidal and subtidal habitats identified for each estuary. These three zones occurred between elevations around Mean Sea Level of -0.86 to 2.42 AMSL for Swartkops, -0.3 to 2.95 m AMSL for Kromme and -0.48 to 3.14 m AMSL for Knysna. A floodplain component was also identified in the Swartkops estuary, which was restricted to the upper reaches. During the last 60 years, losses of intertidal and supratidal salt marsh for Swartkops were 74.31 ha and 30.23 ha respectively, 17.01 ha of intertidal and supratidal salt marsh was lost in Kromme while intertidal salt marsh in Knysna has diminished by 168 ha. These losses were mainly attributed to developmental pressure, although there are indications that rising sea levels are becoming more influential in the lower reaches. The main environmental drivers for salt marsh structure in the Swartkops were shown to be soil moisture content and elevation, soil moisture and organic content for Kromme while elevation and soil redox potential were dominant in Knysna. In a comparison of all three systems, soil moisture content and redox potential were found to be the most important drivers of vegetation distribution. Elevation dictates tidal inundation periodicity and frequency, and thus acts to influence all edaphic factors driving vegetation distribution. Results indicated that the salt marsh surface elevation of the lower and middle sections of the Swartkops, Kromme and Knysna estuaries are generally declining relative to current sea level rise. Where increases in surface elevation (relative to current sea level rise) were recorded, the majority of the accretion occurred after episodic flooding in winter 2011. These increases typically occurred in the upper reaches and were attributed to the deposition of fluvial sediments as a result of these floods. Results for Knysna indicate that while a majority of the salt marsh surface is accreting vertically, only three areas are increasing their elevation at a rate at least equal to current sea level rise. In these areas, developmental pressures will prevent a landward transgression of the salt marsh, forming an artificial “coastal squeeze”. Geomorphological limitations (steep hills adjacent to the salt marsh) will prevent any transgression in the upper reaches of the Kromme Estuary. Supratidal habitat in the upper reaches of the Swartkops estuary, if undeveloped, will provide the only viable habitat for the salt marsh to migrate into, given sufficient surface elevation.
- Full Text:
- Date Issued: 2013
Interaction of metallic nanoparticles with biomedical enzyme target: neuronal nitric oxide synthase
- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2013
- Subjects: Nitric-oxide synthase Alzheimer's disease Arginine Nanoparticles Biochemical markers Biochemical markers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3875 , http://hdl.handle.net/10962/d1001536
- Description: Alzheimer's disease (AD) is the most common type of dementia characterized by intracellular appearance of neurofibrillary tangles, synaptic and neuronal loss; and extracellular accumulation of amyloid-β (Aβ) peptide in senile plaques. The initial causes leading to AD are unknown, and the available treatments are only effective at slowing the degeneration process. The accumulation of arginine in the brain of Alzheimer patients indicates a possible disruption of enzymes responsible for its metabolism. One such enzyme is neuronal nitric oxide synthase (nNOS) and controlling its activity by interacting with nanoparticles may lead to a delay in the onset of the disease. Neuronal nitric oxide synthase was purified using DEAE-Sephacel ion exchange resulting in 10 % yield, 0.43 fold recovery and specific activity 0.09 U/mg. The enzyme was found to be a dimer with a molecular mass of 150 kDa. Characterisation of the nNOS showed an optimum temperature and pH of 50°C and 7.5 respectively, and it was relatively stable at the optimum conditions (t½ = 100 min). The purity was analysed by SDS-PAGE followed by Western blot. Purified nNOS was challenged with 3-7 nm silver and 4-15 nm gold nanoparticles of between synthesized chemical using AgNO3 and either sodium borohydride or sodium citrate. Results showed that gold nanoparticles are more effective at low concentration (5 μM) than silver nanoparticles due to their size difference. Incubation of different concentration of nanoparticles (5, 15, 25, 50 μM) with the purified nNOS showed an initial decrease of 5% in enzyme activity which over time was restored to 80%. This suggests that different nanoparticles are produced in different sizes and interaction over a given time may result in enzyme association–dissociation mechanism. Inhibition studies showed a strong binding of both nanoparticles with Ki values of 1.4 μM and 0.2 μM for silver and gold, respectively. Both nanoparticles inhibited the activity of nNOS extensively as they bound strongly to the inhibition site on the enzyme and were more in contact with fluorophores nanoparticles. This was confirmed by fluorimetry with binding constants of 0.0084 μM and 0.01092 μM for silver and gold, respectively. Results of this study suggest that silver and gold nanoparticles competitively inhibit nNOS.
- Full Text:
- Date Issued: 2013
- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2013
- Subjects: Nitric-oxide synthase Alzheimer's disease Arginine Nanoparticles Biochemical markers Biochemical markers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3875 , http://hdl.handle.net/10962/d1001536
- Description: Alzheimer's disease (AD) is the most common type of dementia characterized by intracellular appearance of neurofibrillary tangles, synaptic and neuronal loss; and extracellular accumulation of amyloid-β (Aβ) peptide in senile plaques. The initial causes leading to AD are unknown, and the available treatments are only effective at slowing the degeneration process. The accumulation of arginine in the brain of Alzheimer patients indicates a possible disruption of enzymes responsible for its metabolism. One such enzyme is neuronal nitric oxide synthase (nNOS) and controlling its activity by interacting with nanoparticles may lead to a delay in the onset of the disease. Neuronal nitric oxide synthase was purified using DEAE-Sephacel ion exchange resulting in 10 % yield, 0.43 fold recovery and specific activity 0.09 U/mg. The enzyme was found to be a dimer with a molecular mass of 150 kDa. Characterisation of the nNOS showed an optimum temperature and pH of 50°C and 7.5 respectively, and it was relatively stable at the optimum conditions (t½ = 100 min). The purity was analysed by SDS-PAGE followed by Western blot. Purified nNOS was challenged with 3-7 nm silver and 4-15 nm gold nanoparticles of between synthesized chemical using AgNO3 and either sodium borohydride or sodium citrate. Results showed that gold nanoparticles are more effective at low concentration (5 μM) than silver nanoparticles due to their size difference. Incubation of different concentration of nanoparticles (5, 15, 25, 50 μM) with the purified nNOS showed an initial decrease of 5% in enzyme activity which over time was restored to 80%. This suggests that different nanoparticles are produced in different sizes and interaction over a given time may result in enzyme association–dissociation mechanism. Inhibition studies showed a strong binding of both nanoparticles with Ki values of 1.4 μM and 0.2 μM for silver and gold, respectively. Both nanoparticles inhibited the activity of nNOS extensively as they bound strongly to the inhibition site on the enzyme and were more in contact with fluorophores nanoparticles. This was confirmed by fluorimetry with binding constants of 0.0084 μM and 0.01092 μM for silver and gold, respectively. Results of this study suggest that silver and gold nanoparticles competitively inhibit nNOS.
- Full Text:
- Date Issued: 2013
Livelihood and coping strategy changes along rural-urban continua with an emphasis on natural resources
- Authors: Evans, Michelle Leigh
- Date: 2013
- Subjects: Natural resources -- South Africa -- Queenstown Natural resources -- South Africa -- Phalaborwa Rural-urban divide -- South Africa -- Queenstown Rural-urban divide -- South Africa -- Phalaborwa Income -- South Africa -- Queenstown Income -- South Africa -- Phalaborwa Women heads of households -- South Africa -- Queenstown Women heads of households -- South Africa -- Phalaborwa Adjustment (Psychology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4731 , http://hdl.handle.net/10962/d1001958
- Description: Rapid urbanisation is one of the greatest challenges facing both developed and developing countries. Sub-Saharan Africa has historically been one of the least developed and least urbanised areas of the world. However, urbanisation is now occurring much more rapidly in countries that have lower levels of per capita income. Therefore, in the coming decades, urban population growth is expected to be more widespread in the developing countries of the world. Most research on the role of natural resources focuses on rural communities and little is known about the contribution these resources make along the rural-urban continuum in small and medium sized towns as well as the contribution to total livelihoods. This is because researchers and policy makers have often treated rural and urban areas and their residents as distinct entities that should be studied in isolation. This, however, is not a true reflection of household livelihoods which often include both rural and urban elements. This study therefore analysed the impact of urbanisation on livelihoods along a rural-urban continuum with an emphasis on natural resources in South Africa. The main characteristics as well as the livelihood portfolios of respondent households were investigated. Secondly, the coping strategies used by households along the rural-urban continuum were explored, and disaggregated according to the gender of the household head. Data were collected along the rural-urban continuum of two small towns, namely Queenstown, located in the Eastern Cape province and Phalaborwa, located in the Limpopo Province of South Africa. Sampling covered the town, peri-urban areas, townships and adjacent rural households. A standardised survey instrument was used to capture household details and livelihood activities and a total of 272 interviews were conducted. The rural areas near both towns were poorer than the township and urban areas with regards to assets, access to employment and annual household income across all cash and non-cash income streams. The engagement in land-based activities increased towards the rural areas. The use of natural resources, as well as the number of resources collected, increased along the continuum towards the rural areas, with 12.0% to 49.0% of urban households, 30.0% to 88.0% of township households and between 80.0% and 100.0% of rural households engaging in the use and collection of natural resources. While natural resource use and collection was lowest in the urban areas, a significant amount of resources were still collected by urban households. Income portfolios for all households were calculated to determine the direct-use value of wild natural capital to livelihoods as well as the contribution made from land (arable and livestock farming), welfare grants and employment. Employment, barring one exception in the rural areas of Phalaborwa, was the largest contributor in terms of mean annual income along the continuum in both towns, followed by grants and pensions in the township and rural areas. In Phalaborwa, however, wild natural capital was found to be the largest contributor to local livelihoods, contributing 48.0% of the mean annual income. Household portfolios become more diversified in the poorer, rural areas as well as in households headed by females. The main shocks reported along the continuum in both Queenstown and Phalaborwa were death in the family, followed by a loss of employment, which was concentrated in male-headed households. Coping strategies resulting in the attainment of cash income fast, such as borrowing money from friends/relatives and cashing in retirements savings were favoured over longer term strategies such as finding local wage employment. Female-headed households were found to rely significantly on social groups or clubs as a coping strategy, highlighting the importance of social capital and social relations in female-headed households
- Full Text:
- Date Issued: 2013
- Authors: Evans, Michelle Leigh
- Date: 2013
- Subjects: Natural resources -- South Africa -- Queenstown Natural resources -- South Africa -- Phalaborwa Rural-urban divide -- South Africa -- Queenstown Rural-urban divide -- South Africa -- Phalaborwa Income -- South Africa -- Queenstown Income -- South Africa -- Phalaborwa Women heads of households -- South Africa -- Queenstown Women heads of households -- South Africa -- Phalaborwa Adjustment (Psychology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4731 , http://hdl.handle.net/10962/d1001958
- Description: Rapid urbanisation is one of the greatest challenges facing both developed and developing countries. Sub-Saharan Africa has historically been one of the least developed and least urbanised areas of the world. However, urbanisation is now occurring much more rapidly in countries that have lower levels of per capita income. Therefore, in the coming decades, urban population growth is expected to be more widespread in the developing countries of the world. Most research on the role of natural resources focuses on rural communities and little is known about the contribution these resources make along the rural-urban continuum in small and medium sized towns as well as the contribution to total livelihoods. This is because researchers and policy makers have often treated rural and urban areas and their residents as distinct entities that should be studied in isolation. This, however, is not a true reflection of household livelihoods which often include both rural and urban elements. This study therefore analysed the impact of urbanisation on livelihoods along a rural-urban continuum with an emphasis on natural resources in South Africa. The main characteristics as well as the livelihood portfolios of respondent households were investigated. Secondly, the coping strategies used by households along the rural-urban continuum were explored, and disaggregated according to the gender of the household head. Data were collected along the rural-urban continuum of two small towns, namely Queenstown, located in the Eastern Cape province and Phalaborwa, located in the Limpopo Province of South Africa. Sampling covered the town, peri-urban areas, townships and adjacent rural households. A standardised survey instrument was used to capture household details and livelihood activities and a total of 272 interviews were conducted. The rural areas near both towns were poorer than the township and urban areas with regards to assets, access to employment and annual household income across all cash and non-cash income streams. The engagement in land-based activities increased towards the rural areas. The use of natural resources, as well as the number of resources collected, increased along the continuum towards the rural areas, with 12.0% to 49.0% of urban households, 30.0% to 88.0% of township households and between 80.0% and 100.0% of rural households engaging in the use and collection of natural resources. While natural resource use and collection was lowest in the urban areas, a significant amount of resources were still collected by urban households. Income portfolios for all households were calculated to determine the direct-use value of wild natural capital to livelihoods as well as the contribution made from land (arable and livestock farming), welfare grants and employment. Employment, barring one exception in the rural areas of Phalaborwa, was the largest contributor in terms of mean annual income along the continuum in both towns, followed by grants and pensions in the township and rural areas. In Phalaborwa, however, wild natural capital was found to be the largest contributor to local livelihoods, contributing 48.0% of the mean annual income. Household portfolios become more diversified in the poorer, rural areas as well as in households headed by females. The main shocks reported along the continuum in both Queenstown and Phalaborwa were death in the family, followed by a loss of employment, which was concentrated in male-headed households. Coping strategies resulting in the attainment of cash income fast, such as borrowing money from friends/relatives and cashing in retirements savings were favoured over longer term strategies such as finding local wage employment. Female-headed households were found to rely significantly on social groups or clubs as a coping strategy, highlighting the importance of social capital and social relations in female-headed households
- Full Text:
- Date Issued: 2013
Livelihoods and natural resource use along the rural-urban continuum
- Authors: Ward, Catherine Dale
- Date: 2013
- Subjects: Natural resources -- South Africa , Human ecology -- South Africa , Cities and towns -- Growth -- South Africa , Natural resources -- Management -- South Africa , Rural poor -- South Africa , Urban poor -- South Africa , Sustainable development -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4727 , http://hdl.handle.net/10962/d1001669 , Natural resources -- South Africa , Human ecology -- South Africa , Cities and towns -- Growth -- South Africa , Natural resources -- Management -- South Africa , Rural poor -- South Africa , Urban poor -- South Africa , Sustainable development -- South Africa
- Description: Over the last century, developing countries have undergone rapid urbanisation resulting in marked social, economic and environmental changes. Africa is the least urbanised continent in the world but trends indicate that it is also the most rapidly urbanising region, accompanied by rising urban poverty. Urbanisation processes are often most pronounced in smaller urban centres since they experience the most severe pressures of population growth. Little is known about the role natural resources play along the rural-urban continuum and even less is known about the contribution of these resources within an urban context, particularly in small urban centres. In many sub-Saharan African cities, urban agriculture (the informal production of food in urban areas) has been used as a strategy to cope with increasing poverty levels but its role remains widely debated and uncertain. This thesis seeks to analyse the impacts of urbanisation on livelihoods and natural resource use, including home gardening and the collection of wild resources, in two South African towns and data was collected along the rural-urban continuum in Queenstown (Eastern Cape province) and Phalaborwa (Limpopo Province). Practices and contributions associated with agriculture and wild resource use were found to be significantly higher in Phalaborwa and this could be attributed to favourable environmental conditions and accessibility to wild resources due to the surrounding Mopani Bushveld. Rural households in Queenstown and Phalaborwa were more reliant on natural resources than their urban counterparts, but still diverse and incorporated a number of land-based and cash income generating strategies. Urban households tended to rely on one primary cash income strategy such as wage employment or state grants. However, natural resources did appear to play a subtle role in urban settings and particularly in the townships, where exclusion of natural resource contributions saw poverty levels increase up to 5%. Home gardening was practised by a wide range of people and not restricted to any one income group and, not surprisingly, wealthy cultivators who had access to resources such as land, water and fertilizer enjoyed increased benefits such as high produce yields. The results obtained suggest that rural-urban dynamics are complex and natural resource use in local livelihoods is contextualised within environmental settings, social preferences and historical contexts. Increasing pressures from the influx of people into small urban centres calls for a better understanding to how these processes are affecting livelihoods and natural resources to ensure sustainable management in the future.
- Full Text:
- Date Issued: 2013
- Authors: Ward, Catherine Dale
- Date: 2013
- Subjects: Natural resources -- South Africa , Human ecology -- South Africa , Cities and towns -- Growth -- South Africa , Natural resources -- Management -- South Africa , Rural poor -- South Africa , Urban poor -- South Africa , Sustainable development -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4727 , http://hdl.handle.net/10962/d1001669 , Natural resources -- South Africa , Human ecology -- South Africa , Cities and towns -- Growth -- South Africa , Natural resources -- Management -- South Africa , Rural poor -- South Africa , Urban poor -- South Africa , Sustainable development -- South Africa
- Description: Over the last century, developing countries have undergone rapid urbanisation resulting in marked social, economic and environmental changes. Africa is the least urbanised continent in the world but trends indicate that it is also the most rapidly urbanising region, accompanied by rising urban poverty. Urbanisation processes are often most pronounced in smaller urban centres since they experience the most severe pressures of population growth. Little is known about the role natural resources play along the rural-urban continuum and even less is known about the contribution of these resources within an urban context, particularly in small urban centres. In many sub-Saharan African cities, urban agriculture (the informal production of food in urban areas) has been used as a strategy to cope with increasing poverty levels but its role remains widely debated and uncertain. This thesis seeks to analyse the impacts of urbanisation on livelihoods and natural resource use, including home gardening and the collection of wild resources, in two South African towns and data was collected along the rural-urban continuum in Queenstown (Eastern Cape province) and Phalaborwa (Limpopo Province). Practices and contributions associated with agriculture and wild resource use were found to be significantly higher in Phalaborwa and this could be attributed to favourable environmental conditions and accessibility to wild resources due to the surrounding Mopani Bushveld. Rural households in Queenstown and Phalaborwa were more reliant on natural resources than their urban counterparts, but still diverse and incorporated a number of land-based and cash income generating strategies. Urban households tended to rely on one primary cash income strategy such as wage employment or state grants. However, natural resources did appear to play a subtle role in urban settings and particularly in the townships, where exclusion of natural resource contributions saw poverty levels increase up to 5%. Home gardening was practised by a wide range of people and not restricted to any one income group and, not surprisingly, wealthy cultivators who had access to resources such as land, water and fertilizer enjoyed increased benefits such as high produce yields. The results obtained suggest that rural-urban dynamics are complex and natural resource use in local livelihoods is contextualised within environmental settings, social preferences and historical contexts. Increasing pressures from the influx of people into small urban centres calls for a better understanding to how these processes are affecting livelihoods and natural resources to ensure sustainable management in the future.
- Full Text:
- Date Issued: 2013
Log analysis aided by latent semantic mapping
- Authors: Buys, Stephanus
- Date: 2013 , 2013-04-14
- Subjects: Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4575 , http://hdl.handle.net/10962/d1002963 , Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Description: In an age of zero-day exploits and increased on-line attacks on computing infrastructure, operational security practitioners are becoming increasingly aware of the value of the information captured in log events. Analysis of these events is critical during incident response, forensic investigations related to network breaches, hacking attacks and data leaks. Such analysis has led to the discipline of Security Event Analysis, also known as Log Analysis. There are several challenges when dealing with events, foremost being the increased volumes at which events are often generated and stored. Furthermore, events are often captured as unstructured data, with very little consistency in the formats or contents of the events. In this environment, security analysts and implementers of Log Management (LM) or Security Information and Event Management (SIEM) systems face the daunting task of identifying, classifying and disambiguating massive volumes of events in order for security analysis and automation to proceed. Latent Semantic Mapping (LSM) is a proven paradigm shown to be an effective method of, among other things, enabling word clustering, document clustering, topic clustering and semantic inference. This research is an investigation into the practical application of LSM in the discipline of Security Event Analysis, showing the value of using LSM to assist practitioners in identifying types of events, classifying events as belonging to certain sources or technologies and disambiguating different events from each other. The culmination of this research presents adaptations to traditional natural language processing techniques that resulted in improved efficacy of LSM when dealing with Security Event Analysis. This research provides strong evidence supporting the wider adoption and use of LSM, as well as further investigation into Security Event Analysis assisted by LSM and other natural language or computer-learning processing techniques. , LaTeX with hyperref package , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Buys, Stephanus
- Date: 2013 , 2013-04-14
- Subjects: Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4575 , http://hdl.handle.net/10962/d1002963 , Latent semantic indexing , Data mining , Computer networks -- Security measures , Computer hackers , Computer security
- Description: In an age of zero-day exploits and increased on-line attacks on computing infrastructure, operational security practitioners are becoming increasingly aware of the value of the information captured in log events. Analysis of these events is critical during incident response, forensic investigations related to network breaches, hacking attacks and data leaks. Such analysis has led to the discipline of Security Event Analysis, also known as Log Analysis. There are several challenges when dealing with events, foremost being the increased volumes at which events are often generated and stored. Furthermore, events are often captured as unstructured data, with very little consistency in the formats or contents of the events. In this environment, security analysts and implementers of Log Management (LM) or Security Information and Event Management (SIEM) systems face the daunting task of identifying, classifying and disambiguating massive volumes of events in order for security analysis and automation to proceed. Latent Semantic Mapping (LSM) is a proven paradigm shown to be an effective method of, among other things, enabling word clustering, document clustering, topic clustering and semantic inference. This research is an investigation into the practical application of LSM in the discipline of Security Event Analysis, showing the value of using LSM to assist practitioners in identifying types of events, classifying events as belonging to certain sources or technologies and disambiguating different events from each other. The culmination of this research presents adaptations to traditional natural language processing techniques that resulted in improved efficacy of LSM when dealing with Security Event Analysis. This research provides strong evidence supporting the wider adoption and use of LSM, as well as further investigation into Security Event Analysis assisted by LSM and other natural language or computer-learning processing techniques. , LaTeX with hyperref package , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa
- Authors: McConnachie, Lauren Bernyse
- Date: 2013
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Sand dune ecology -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Sedimentation and deposition -- South Africa -- Eastern Cape Beach erosion -- South Africa -- Eastern Cape Coastal zone management -- South Africa -- Eastern Cape Shore protection -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4804 , http://hdl.handle.net/10962/d1001904
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed , Maiden name: Elkington, Lauren
- Full Text:
- Date Issued: 2013
- Authors: McConnachie, Lauren Bernyse
- Date: 2013
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Sand dune ecology -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Sedimentation and deposition -- South Africa -- Eastern Cape Beach erosion -- South Africa -- Eastern Cape Coastal zone management -- South Africa -- Eastern Cape Shore protection -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4804 , http://hdl.handle.net/10962/d1001904
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed , Maiden name: Elkington, Lauren
- Full Text:
- Date Issued: 2013
Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa
- Authors: Elkington, Lauren
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20984 , http://hdl.handle.net/10962/5879
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed.
- Full Text:
- Date Issued: 2013
- Authors: Elkington, Lauren
- Date: 2013
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20984 , http://hdl.handle.net/10962/5879
- Description: Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed.
- Full Text:
- Date Issued: 2013
Profiling for volatile compounds in the Kgalagadi desert truffle
- Authors: Bogopa, Juda
- Date: 2013
- Subjects: Desert plants -- Botswana -- Kgalagadi District Supercritical fluid extraction Gas chromatography Mass spectrometry Tuberaceae -- Analysis -- Botswana -- Kgalagadi District Truffles -- Analysis -- Botswana -- Kgalagadi District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4280 , http://hdl.handle.net/10962/d1002006
- Description: The thesis focuses on ‘green’ sample preparation techniques that utilise minimal or no organic solvents thereby producing negligible volumes of organic waste, to ensure safety both to user and the environment. Volatile compounds were extracted and pre-concentrated from Kgalagadi desert truffles (kalaharituber) by headspace solid phase microextraction (HSSPME) and supercritical fluid extraction (SFE). PHWE was employed for the extraction of amino acids and fatty acids. Subsequent analysis of volatile compounds was carried out by gas chromatography coupled with mass spectrometry. Four types of HS-SPME fibers (PDMS 100 μm, PDMS 7 μm, Polyacrylate 85 μm, CAR/DVB/PDMS 50/30 μm) were evaluated. A total of 24 volatile compounds with a molecular weight range from 110 to 354, the most prominent peak being 2-t-Butyl-2,3-dimethyl-3-buten-1-ol (C₁₀H₂₀O, MW 156) were detected after sampling with a PDMS 100 μm fiber. Less volatile compounds were detected after SFE with CO2. A total of 16 amino acids were identified while 17 fatty acids (MW from 132.12 to 367.49) were also identified. The characteristic profile of the Kgalagadi desert truffle was found to contain mainly fatty acid methyl esters and unsaturated aliphatic hydrocarbons. The most prominent compound peaks identified were; 2-t-butyl-2,3-dimethyl- 3-buten-1-ol, disulfide, ethyl benzoic acid 2-4-dhydroxy-3,6-dimethyl-methyl ester, 8,11- octadecanoic acid methyl ester, benzoic acid, 2,4-dihydroxy-3,6-dimethyl-methyl ester, isoquinoline, 1 butyl-3,4-dihydro and 3-heptanone, 6 methyl. Optimization results indicated that fresh slices from the heart of truffles were the best to use for HS-SPME-GCMS volatile compound analysis as they showed a higher sensitivity
- Full Text:
- Date Issued: 2013
- Authors: Bogopa, Juda
- Date: 2013
- Subjects: Desert plants -- Botswana -- Kgalagadi District Supercritical fluid extraction Gas chromatography Mass spectrometry Tuberaceae -- Analysis -- Botswana -- Kgalagadi District Truffles -- Analysis -- Botswana -- Kgalagadi District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4280 , http://hdl.handle.net/10962/d1002006
- Description: The thesis focuses on ‘green’ sample preparation techniques that utilise minimal or no organic solvents thereby producing negligible volumes of organic waste, to ensure safety both to user and the environment. Volatile compounds were extracted and pre-concentrated from Kgalagadi desert truffles (kalaharituber) by headspace solid phase microextraction (HSSPME) and supercritical fluid extraction (SFE). PHWE was employed for the extraction of amino acids and fatty acids. Subsequent analysis of volatile compounds was carried out by gas chromatography coupled with mass spectrometry. Four types of HS-SPME fibers (PDMS 100 μm, PDMS 7 μm, Polyacrylate 85 μm, CAR/DVB/PDMS 50/30 μm) were evaluated. A total of 24 volatile compounds with a molecular weight range from 110 to 354, the most prominent peak being 2-t-Butyl-2,3-dimethyl-3-buten-1-ol (C₁₀H₂₀O, MW 156) were detected after sampling with a PDMS 100 μm fiber. Less volatile compounds were detected after SFE with CO2. A total of 16 amino acids were identified while 17 fatty acids (MW from 132.12 to 367.49) were also identified. The characteristic profile of the Kgalagadi desert truffle was found to contain mainly fatty acid methyl esters and unsaturated aliphatic hydrocarbons. The most prominent compound peaks identified were; 2-t-butyl-2,3-dimethyl- 3-buten-1-ol, disulfide, ethyl benzoic acid 2-4-dhydroxy-3,6-dimethyl-methyl ester, 8,11- octadecanoic acid methyl ester, benzoic acid, 2,4-dihydroxy-3,6-dimethyl-methyl ester, isoquinoline, 1 butyl-3,4-dihydro and 3-heptanone, 6 methyl. Optimization results indicated that fresh slices from the heart of truffles were the best to use for HS-SPME-GCMS volatile compound analysis as they showed a higher sensitivity
- Full Text:
- Date Issued: 2013
Revision of Aloiampelos Klopper & Gideon F.Sm. (xanthorrhoeaceae subfam. asphodeloideae)
- Authors: Ellis, Kristen
- Date: 2013
- Subjects: Xanthorrhoeaceae , Asparagales
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10642 , http://hdl.handle.net/10948/d1020955
- Description: The genus Aloiampelos Klopper & Gideon F.Sm., previously treated as Aloe L. Ser. Macrifoliae (Sect. Prolongatae), comprises seven species with barely succulent leaves that are popularly known as rambling, scrambling or climbing aloes, because they make use of surrounding trees and shrubs for support. The rambling aloes are centered in the Eastern Cape but some species have disjunct distributions in the Western Cape and KwaZulu-Natal. Many are widely used in gardens and landscaping. With their rambling habit and weakly succulent leaves, the genus is widely considered to be an old lineage among alooid genera. Species concepts within the genus remain contentious, with disagreement amongst taxonomists with respect to the recognition of some taxa at the rank of variety. Morphology, historical taxonomy, palynology and phylogenetics of the genus were investigated. The occasional presence of minute cilia on the sheathing leaf bases and distinct lineation of the leaf sheaths of Aloiampelos tenuior var. decidua and Aloiampelos tenuior var. rubriflora were the most important outcomes of the morphological study. The pollen grains of all species studied were very similar in grain shape and exine surface pattern, with only minor differences in grain size. Ordination analyses showed that grain length and muri length were useful at the infraspecific level, with Aloiampelos tenuior “orange” separating clearly from the other varieties. Pollen morphology was therefore not informative as a taxonomic character at species level when used in isolation, but may be useful when used in conjunction with other characteristics. Preliminary analyses of two plastid barcoding regions (matK and rbcL) and nuclear ITS have confirmed that Aloiampelos is monophyletic. These barcoding markers were not informative in assessing the species boundaries among the closely related taxa in the genus and morphological assessments were therefore used to elucidate relationships at the species rank. A key is given for the genus, integrating the findings of the study.
- Full Text:
- Date Issued: 2013
- Authors: Ellis, Kristen
- Date: 2013
- Subjects: Xanthorrhoeaceae , Asparagales
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10642 , http://hdl.handle.net/10948/d1020955
- Description: The genus Aloiampelos Klopper & Gideon F.Sm., previously treated as Aloe L. Ser. Macrifoliae (Sect. Prolongatae), comprises seven species with barely succulent leaves that are popularly known as rambling, scrambling or climbing aloes, because they make use of surrounding trees and shrubs for support. The rambling aloes are centered in the Eastern Cape but some species have disjunct distributions in the Western Cape and KwaZulu-Natal. Many are widely used in gardens and landscaping. With their rambling habit and weakly succulent leaves, the genus is widely considered to be an old lineage among alooid genera. Species concepts within the genus remain contentious, with disagreement amongst taxonomists with respect to the recognition of some taxa at the rank of variety. Morphology, historical taxonomy, palynology and phylogenetics of the genus were investigated. The occasional presence of minute cilia on the sheathing leaf bases and distinct lineation of the leaf sheaths of Aloiampelos tenuior var. decidua and Aloiampelos tenuior var. rubriflora were the most important outcomes of the morphological study. The pollen grains of all species studied were very similar in grain shape and exine surface pattern, with only minor differences in grain size. Ordination analyses showed that grain length and muri length were useful at the infraspecific level, with Aloiampelos tenuior “orange” separating clearly from the other varieties. Pollen morphology was therefore not informative as a taxonomic character at species level when used in isolation, but may be useful when used in conjunction with other characteristics. Preliminary analyses of two plastid barcoding regions (matK and rbcL) and nuclear ITS have confirmed that Aloiampelos is monophyletic. These barcoding markers were not informative in assessing the species boundaries among the closely related taxa in the genus and morphological assessments were therefore used to elucidate relationships at the species rank. A key is given for the genus, integrating the findings of the study.
- Full Text:
- Date Issued: 2013