A comparison of web-based technologies to serve images from an Oracle9i database
- Authors: Swales, Dylan
- Date: 2004 , 2013-06-18
- Subjects: Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4583 , http://hdl.handle.net/10962/d1004380 , Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Description: The nature of Internet and Intranet Web applications has changed from a static content-distribution medium into an interactive, dynamic medium, often used to serve multimedia from back-end object-relational databases to Web-enabled clients. Consequently, developers need to make an informed technological choice for developing software that supports a Web-based application for distributing multimedia over networks. This decision is based on several factors. Among the factors are ease of programming, richness of features, scalability, and performance. The research focuses on these key factors when distributing images from an Oracle9i database using Java Servlets, JSP, ASP, and ASP.NET as the server-side development technologies. Prototype applications are developed and tested within each technology: one for single image serving and the other for multiple image serving. A matrix of recommendations is provided to distinguish which technology, or combination of technologies, provides the best performance and development platform for image serving within the studied envirorunent. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
- Authors: Swales, Dylan
- Date: 2004 , 2013-06-18
- Subjects: Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4583 , http://hdl.handle.net/10962/d1004380 , Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Description: The nature of Internet and Intranet Web applications has changed from a static content-distribution medium into an interactive, dynamic medium, often used to serve multimedia from back-end object-relational databases to Web-enabled clients. Consequently, developers need to make an informed technological choice for developing software that supports a Web-based application for distributing multimedia over networks. This decision is based on several factors. Among the factors are ease of programming, richness of features, scalability, and performance. The research focuses on these key factors when distributing images from an Oracle9i database using Java Servlets, JSP, ASP, and ASP.NET as the server-side development technologies. Prototype applications are developed and tested within each technology: one for single image serving and the other for multiple image serving. A matrix of recommendations is provided to distinguish which technology, or combination of technologies, provides the best performance and development platform for image serving within the studied envirorunent. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
The execution of the financial management function in small to medium-sized building contractors as a means of promoting business sustainability
- Authors: Bekker, Jakobus Petrus
- Date: 2004
- Subjects: Contractors' operation -- Finance , Construction industry -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11004 , http://hdl.handle.net/10948/336 , Contractors' operation -- Finance , Construction industry -- Finance
- Description: The objective of this study was to investigate the extent to which small to medium-sized building contractors beneficially utilise the financial management function in their enterprises to improve and ensure business sustainability. Financial management focuses on the principles of decision-making, which requires action, without perfect knowledge of the outcome. To effectively execute the financial function, using the primary inputs in decision-making, financial management requires the ability to: understand and interpret financial statements and reports; make reasoned and objective decisions in controlling the operations of the enterprise; have a thorough knowledge of the internal functioning of the enterprise; and have a thorough knowledge of current and expected future economic conditions in the external environment. To do this, requires an effectively applied financial management function in the enterprises, which includes the utilisation of the financial management criteria to ensure business sustainability. However, without an appreciation of what financial management is, how important financial management is, and how financial management must be applied in the enterprise, small to medium-sized building contractors will find it difficult to effectively perform the financial management function and its different activities. It was therefore important to determine how well owners and construction managers of the average small to medium-sized building contractor deal with and utilise the financial management function in their enterprises. Consequently, a survey was carried out amongst small to medium-sized building contractors in the Nelson Mandela Metropolitan Municipal (NMMM) area, which revealed information that was used to come to certain conclusions: Firstly, it can be concluded that the financial management function is generally exercised superficially. This is supported by the responses of small to medium-sized building contractors, which implied that more than half the contractors do not fully perform financial management tasks. Secondly, it was concluded that the financial management criteria generally do not play a role in the business sustainability considerations of small to medium-sized building contractors. This is supported by the results, which imply that more than half the contractors do not fully utilise the financial management criteria.
- Full Text:
- Date Issued: 2004
- Authors: Bekker, Jakobus Petrus
- Date: 2004
- Subjects: Contractors' operation -- Finance , Construction industry -- Finance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11004 , http://hdl.handle.net/10948/336 , Contractors' operation -- Finance , Construction industry -- Finance
- Description: The objective of this study was to investigate the extent to which small to medium-sized building contractors beneficially utilise the financial management function in their enterprises to improve and ensure business sustainability. Financial management focuses on the principles of decision-making, which requires action, without perfect knowledge of the outcome. To effectively execute the financial function, using the primary inputs in decision-making, financial management requires the ability to: understand and interpret financial statements and reports; make reasoned and objective decisions in controlling the operations of the enterprise; have a thorough knowledge of the internal functioning of the enterprise; and have a thorough knowledge of current and expected future economic conditions in the external environment. To do this, requires an effectively applied financial management function in the enterprises, which includes the utilisation of the financial management criteria to ensure business sustainability. However, without an appreciation of what financial management is, how important financial management is, and how financial management must be applied in the enterprise, small to medium-sized building contractors will find it difficult to effectively perform the financial management function and its different activities. It was therefore important to determine how well owners and construction managers of the average small to medium-sized building contractor deal with and utilise the financial management function in their enterprises. Consequently, a survey was carried out amongst small to medium-sized building contractors in the Nelson Mandela Metropolitan Municipal (NMMM) area, which revealed information that was used to come to certain conclusions: Firstly, it can be concluded that the financial management function is generally exercised superficially. This is supported by the responses of small to medium-sized building contractors, which implied that more than half the contractors do not fully perform financial management tasks. Secondly, it was concluded that the financial management criteria generally do not play a role in the business sustainability considerations of small to medium-sized building contractors. This is supported by the results, which imply that more than half the contractors do not fully utilise the financial management criteria.
- Full Text:
- Date Issued: 2004
DRUBIS : a distributed face-identification experimentation framework - design, implementation and performance issues
- Authors: Ndlangisa, Mboneli
- Date: 2004
- Subjects: Principal components analysis , Human face recognition (Computer science) , Image processing , Biometric identification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4704 , http://hdl.handle.net/10962/d1015768
- Description: We report on the design, implementation and performance issues of the DRUBIS (Distributed Rhodes University Biometric Identification System) experimentation framework. The Principal Component Analysis (PCA) face-recognition approach is used as a case study. DRUBIS is a flexible experimentation framework, distributed over a number of modules that are easily pluggable and swappable, allowing for the easy construction of prototype systems. Web services are the logical means of distributing DRUBIS components and a number of prototype applications have been implemented from this framework. Different popular PCA face-recognition related experiments were used to evaluate our experimentation framework. We extract recognition performance measures from these experiments. In particular, we use the framework for a more indepth study of the suitability of the DFFS (Difference From Face Space) metric as a means for image classification in the area of race and gender determination.
- Full Text:
- Date Issued: 2004
- Authors: Ndlangisa, Mboneli
- Date: 2004
- Subjects: Principal components analysis , Human face recognition (Computer science) , Image processing , Biometric identification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4704 , http://hdl.handle.net/10962/d1015768
- Description: We report on the design, implementation and performance issues of the DRUBIS (Distributed Rhodes University Biometric Identification System) experimentation framework. The Principal Component Analysis (PCA) face-recognition approach is used as a case study. DRUBIS is a flexible experimentation framework, distributed over a number of modules that are easily pluggable and swappable, allowing for the easy construction of prototype systems. Web services are the logical means of distributing DRUBIS components and a number of prototype applications have been implemented from this framework. Different popular PCA face-recognition related experiments were used to evaluate our experimentation framework. We extract recognition performance measures from these experiments. In particular, we use the framework for a more indepth study of the suitability of the DFFS (Difference From Face Space) metric as a means for image classification in the area of race and gender determination.
- Full Text:
- Date Issued: 2004
Gold exploration northeast of Ngundu Halt, northern marginal zone of the Limpopo Belt, Zimbabwe
- Authors: Simango, Robert Zulu
- Date: 2004 , 2013-05-30
- Subjects: Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5007 , http://hdl.handle.net/10962/d1005844 , Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Description: Gold exploration was conducted in northern margin, granulite-facies rocks of the Limpopo Belt. Methods used in the prospecting include drainage, soil and rock geochemistry, geophysical surveys, geological mapping, trenching and diamond drilling. These techniques successfully led to the discovery of two medium size, mesothermal gold deposits (Grid 2s and Grid 4). Objectives of this study were to (a) document the exploration methodology used; (b) describe the regional geology; (c) establish a mineral deposit model; (d) outline the methods and results of various exploration techniques; (e) outline follow-up procedures and evaluation of anomalies; and (f) discuss results of the exploration exercise and conclusions. The granulite-facies terrain comprises Charno-enderbites, mafic and felsic to intermediate metavolcanic rocks and meta-sediments. Renco Mine situated immediately east of the study area, was selected as the ore deposit model for the exploration program. Gold mineralization occurs in shear and thrust zones within an enderbite. The gold deposits are structurally controlled by a first-order, Sinistral transcrustal Mauch Shear Zone, which is parallel to a regional east-northeast penetrative foliation. The deposits are in dilation zones where the Mauch Shear (a) is intersected by a dextral east-west shear (Grid 2s), or (b) has a sinistral splay (Grid 4 and Renco). Close to these deposits, the Mauch Shear is in contact with a "greenstone belt", which is a possible source of crustal metamorphic ore fluids and gold. The Grid 2s deposit contains fine-grained, disseminated free gold, and small amounts of pyrrhotite, pyrite and chalcopyrite in quartz veins within third-order shears in K-feldspar granite. K-feldspar, sericitic, silicic, sulphidation and carbonate alteration characterizes the deposit, which has a proposed mantle-degassing model. The Grid 4 deposit is magmatic porphyry-type, with CuMo and Au in third- and fourth-order shears respectively. Mineralization comprises disseminated to semi-massive pyrrhotite, pyrite, chalcopyrite, sphalerite, bismuth, molybdenite and gold. Wall rock alteration includes biotitic, chloritic, silicic, sulphidation and carbonate. In Grid 2s, Grid 4 and Renco deposits, the alteration mineral assemblages are in three facies, which are granulite, amphibolte and greenschist. In the three deposits, the mineralization occurs with the amphibolite-facies, indicating post-peak, retrograde metamorphic conditions. , Illustrations (maps) only available in print form at Cory Library , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
- Authors: Simango, Robert Zulu
- Date: 2004 , 2013-05-30
- Subjects: Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5007 , http://hdl.handle.net/10962/d1005844 , Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Description: Gold exploration was conducted in northern margin, granulite-facies rocks of the Limpopo Belt. Methods used in the prospecting include drainage, soil and rock geochemistry, geophysical surveys, geological mapping, trenching and diamond drilling. These techniques successfully led to the discovery of two medium size, mesothermal gold deposits (Grid 2s and Grid 4). Objectives of this study were to (a) document the exploration methodology used; (b) describe the regional geology; (c) establish a mineral deposit model; (d) outline the methods and results of various exploration techniques; (e) outline follow-up procedures and evaluation of anomalies; and (f) discuss results of the exploration exercise and conclusions. The granulite-facies terrain comprises Charno-enderbites, mafic and felsic to intermediate metavolcanic rocks and meta-sediments. Renco Mine situated immediately east of the study area, was selected as the ore deposit model for the exploration program. Gold mineralization occurs in shear and thrust zones within an enderbite. The gold deposits are structurally controlled by a first-order, Sinistral transcrustal Mauch Shear Zone, which is parallel to a regional east-northeast penetrative foliation. The deposits are in dilation zones where the Mauch Shear (a) is intersected by a dextral east-west shear (Grid 2s), or (b) has a sinistral splay (Grid 4 and Renco). Close to these deposits, the Mauch Shear is in contact with a "greenstone belt", which is a possible source of crustal metamorphic ore fluids and gold. The Grid 2s deposit contains fine-grained, disseminated free gold, and small amounts of pyrrhotite, pyrite and chalcopyrite in quartz veins within third-order shears in K-feldspar granite. K-feldspar, sericitic, silicic, sulphidation and carbonate alteration characterizes the deposit, which has a proposed mantle-degassing model. The Grid 4 deposit is magmatic porphyry-type, with CuMo and Au in third- and fourth-order shears respectively. Mineralization comprises disseminated to semi-massive pyrrhotite, pyrite, chalcopyrite, sphalerite, bismuth, molybdenite and gold. Wall rock alteration includes biotitic, chloritic, silicic, sulphidation and carbonate. In Grid 2s, Grid 4 and Renco deposits, the alteration mineral assemblages are in three facies, which are granulite, amphibolte and greenschist. In the three deposits, the mineralization occurs with the amphibolite-facies, indicating post-peak, retrograde metamorphic conditions. , Illustrations (maps) only available in print form at Cory Library , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
Screening of the white margined sole, Synaptura marginata (Soleidae), as a candidate for aquaculture in South Africa
- Authors: Thompson, Ernst Frederick
- Date: 2004
- Subjects: Flatfishes -- South Africa , Aquaculture -- South Africa , Soleidae -- South Africa , Soleidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5207 , http://hdl.handle.net/10962/d1004523 , Flatfishes -- South Africa , Aquaculture -- South Africa , Soleidae -- South Africa , Soleidae
- Description: The white margined sole Synaptura marginata (Soleidae) was isolated as the most likely candidate for flatfish aquaculture in South Africa. The aim of the study was to screen the sole as a candidate aquaculture species by way of a comprehensive study of its biology and life history strategy and to identify possible "bottlenecks". The study was undertaken on the assumption that the biological data would provide valuable information for developing specific technologies that might be required for the farming of this species. Specimens were collected monthly by spearing along the Eastern Cape coast of South Africa between December 2000 and March 2002. Length-at-age data required for modeling the growth of S. marginata was obtained from sectioned otoliths. A Von Bertalanffy growth model with an absolute error structure best describes the growth for this species. The model parameters were: L∞ = 429.5 mm TL, K = 0.24 and t₀ = -1 .79 years. Analysis of gut contents showed that S. marginata feed exclusively on polychaete worms, mainly of the genus Morphysa. S. marginata shows a protracted summer spawning season of six months, from October to April. This was determined by the calculation of a monthly gonadosomatic index and a macroscopic maturity scale. Histological examination of the ovaries revealed five ovarian developmental stages. Size at 50% and 100% sexual maturity for females was calculated to be 235 mm TL and 300 mm TL (ca. 1.5 - 2.5 years of age) and all males> 154 mm TL were mature. S. marginata is a batch spawner, releasing a minimum of 3 batches of eggs per year. Relative fecundity is high (34000 eggs per year I kg) and this coupled with the protracted spawning season would make it possible to obtain adequate numbers of juveniles (for farming) for approximately five to six months of the year. Comparative analysis of the biological characteristics in relation to other soles farmed elsewhere in the world suggests that S. marginata is a suitable candidate for marine fish culture in South Africa.
- Full Text:
- Date Issued: 2004
- Authors: Thompson, Ernst Frederick
- Date: 2004
- Subjects: Flatfishes -- South Africa , Aquaculture -- South Africa , Soleidae -- South Africa , Soleidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5207 , http://hdl.handle.net/10962/d1004523 , Flatfishes -- South Africa , Aquaculture -- South Africa , Soleidae -- South Africa , Soleidae
- Description: The white margined sole Synaptura marginata (Soleidae) was isolated as the most likely candidate for flatfish aquaculture in South Africa. The aim of the study was to screen the sole as a candidate aquaculture species by way of a comprehensive study of its biology and life history strategy and to identify possible "bottlenecks". The study was undertaken on the assumption that the biological data would provide valuable information for developing specific technologies that might be required for the farming of this species. Specimens were collected monthly by spearing along the Eastern Cape coast of South Africa between December 2000 and March 2002. Length-at-age data required for modeling the growth of S. marginata was obtained from sectioned otoliths. A Von Bertalanffy growth model with an absolute error structure best describes the growth for this species. The model parameters were: L∞ = 429.5 mm TL, K = 0.24 and t₀ = -1 .79 years. Analysis of gut contents showed that S. marginata feed exclusively on polychaete worms, mainly of the genus Morphysa. S. marginata shows a protracted summer spawning season of six months, from October to April. This was determined by the calculation of a monthly gonadosomatic index and a macroscopic maturity scale. Histological examination of the ovaries revealed five ovarian developmental stages. Size at 50% and 100% sexual maturity for females was calculated to be 235 mm TL and 300 mm TL (ca. 1.5 - 2.5 years of age) and all males> 154 mm TL were mature. S. marginata is a batch spawner, releasing a minimum of 3 batches of eggs per year. Relative fecundity is high (34000 eggs per year I kg) and this coupled with the protracted spawning season would make it possible to obtain adequate numbers of juveniles (for farming) for approximately five to six months of the year. Comparative analysis of the biological characteristics in relation to other soles farmed elsewhere in the world suggests that S. marginata is a suitable candidate for marine fish culture in South Africa.
- Full Text:
- Date Issued: 2004
A critical analysis of the influence of the "Prevention of the illegal eviction from and unlawful occupation of Land Act 19 of 1998" on investment in residential income-producing property
- Authors: Botha, Brink
- Date: 2004
- Subjects: Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11005 , http://hdl.handle.net/10948/321 , Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Description: This research will focus on the influence of legislation (as indicated in this research) on the investment decision in residential income-producing property. Assumptions, as recorded in the hypothesis of this study, indicate that the legislation had a changing influence on the investment decision in residential income-producing property in comparison to the time period prior to the promulgation of the legislation. The research methodology will be based on a comparative analysis of the current legislation and the proposed Draft Amendment Bill. This analysis will be tested by means of a case study analysis incorporating a phenomenological study based on written data. The problems, sub-problems and hypothesis will be addressed and tested in this research in conjunction with the prescribed research methodology. This research is concluded by means of a synopsis and recommendations.
- Full Text:
- Date Issued: 2004
- Authors: Botha, Brink
- Date: 2004
- Subjects: Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11005 , http://hdl.handle.net/10948/321 , Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Description: This research will focus on the influence of legislation (as indicated in this research) on the investment decision in residential income-producing property. Assumptions, as recorded in the hypothesis of this study, indicate that the legislation had a changing influence on the investment decision in residential income-producing property in comparison to the time period prior to the promulgation of the legislation. The research methodology will be based on a comparative analysis of the current legislation and the proposed Draft Amendment Bill. This analysis will be tested by means of a case study analysis incorporating a phenomenological study based on written data. The problems, sub-problems and hypothesis will be addressed and tested in this research in conjunction with the prescribed research methodology. This research is concluded by means of a synopsis and recommendations.
- Full Text:
- Date Issued: 2004
The challenge of applying systematic conservation planning to the marine environment using expert knowledge (focus: Sparidae)
- Authors: Bause, Mariëtte
- Date: 2004
- Subjects: Marine parks and reserves -- South Africa , Nature conservation -- South Africa , Fishery conservation -- South Africa , Sparidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11064 , http://hdl.handle.net/10948/343 , Marine parks and reserves -- South Africa , Nature conservation -- South Africa , Fishery conservation -- South Africa , Sparidae
- Description: Although the marine environment has generally been considered to be less in need of attention from conservationists, politicians and managers than the terrestrial environment, there has been an increasing appreciation that there is little left in the marine environment that can be considered unaltered by humans. Conservation action is therefore urgently needed to protect marine populations, species and environments from anthropogenic pressures. Since overharvesting seems to be the main cause of the collapse in coastal ecosystems, areas need to be protected so that stocks can recover. However, the proclamation of such marine protected areas (MPAs) need to be well planned to ensure that species are well represented and that their biological requirements are met in the long term. While terrestrial conservation planners have started to incorporate biological, social and economic information into so-called systematic conservation plans, marine planners have been more hesitant to use these approaches due to the greater openness of the ocean (with the associated greater dispersal of marine organisms and propogules, lower levels of endemism, and lack of ownership) and the paucity of available information. The current study aimed to investigate the applicability of systematic approaches to the process of selecting sites for a network of potential replenishment zones for seabream species that could supplement protection already afforded by existing no-fishing reserves. Since many of these seabream species are popular targets in both the recreational and commercial linefishery sectors, they have been overexploited and are in need of additional protection. Information on these species and the diversity of their associated reefs were obtained through consultations with scientists, managers and resource-users (namely SCUBA divers, spearfishers as well as recreational and commercial fishers). These data were obtained during workshops where Participatory Rural Appraisal (PRA) scoring and mapping methods were applied. Although ordinal-scale, rather than interval-or ratio-scale data were obtained, these data could be used in an interactive selection process. Because these methods require relatively cheap materials and few personnel, they could be used to collect information where limited budgets are available. Quantitative targets for the protection of individual species were set on the basis of their status in the Marine Living Resource Act, since this reflected their different requirements for protection. A preliminary investigation indicated that the current no-fishing reserves effectively achieved most of these goals for seabream species. The selection of sites for the replenishment network was based on irreplaceability analyses, while decisions between sites with lower irreplaceability values were based on explicit design rules. A total of 26 sites were required to achieve targets for all species. These replenishment zones could potentially be established, managed and monitored by voluntary community groups. This study therefore indicated that systematic conservation planning can successfully be applied to the marine environment, while the involvement of stakeholders is crucial to ensure that conservation action is supported.
- Full Text:
- Date Issued: 2004
- Authors: Bause, Mariëtte
- Date: 2004
- Subjects: Marine parks and reserves -- South Africa , Nature conservation -- South Africa , Fishery conservation -- South Africa , Sparidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11064 , http://hdl.handle.net/10948/343 , Marine parks and reserves -- South Africa , Nature conservation -- South Africa , Fishery conservation -- South Africa , Sparidae
- Description: Although the marine environment has generally been considered to be less in need of attention from conservationists, politicians and managers than the terrestrial environment, there has been an increasing appreciation that there is little left in the marine environment that can be considered unaltered by humans. Conservation action is therefore urgently needed to protect marine populations, species and environments from anthropogenic pressures. Since overharvesting seems to be the main cause of the collapse in coastal ecosystems, areas need to be protected so that stocks can recover. However, the proclamation of such marine protected areas (MPAs) need to be well planned to ensure that species are well represented and that their biological requirements are met in the long term. While terrestrial conservation planners have started to incorporate biological, social and economic information into so-called systematic conservation plans, marine planners have been more hesitant to use these approaches due to the greater openness of the ocean (with the associated greater dispersal of marine organisms and propogules, lower levels of endemism, and lack of ownership) and the paucity of available information. The current study aimed to investigate the applicability of systematic approaches to the process of selecting sites for a network of potential replenishment zones for seabream species that could supplement protection already afforded by existing no-fishing reserves. Since many of these seabream species are popular targets in both the recreational and commercial linefishery sectors, they have been overexploited and are in need of additional protection. Information on these species and the diversity of their associated reefs were obtained through consultations with scientists, managers and resource-users (namely SCUBA divers, spearfishers as well as recreational and commercial fishers). These data were obtained during workshops where Participatory Rural Appraisal (PRA) scoring and mapping methods were applied. Although ordinal-scale, rather than interval-or ratio-scale data were obtained, these data could be used in an interactive selection process. Because these methods require relatively cheap materials and few personnel, they could be used to collect information where limited budgets are available. Quantitative targets for the protection of individual species were set on the basis of their status in the Marine Living Resource Act, since this reflected their different requirements for protection. A preliminary investigation indicated that the current no-fishing reserves effectively achieved most of these goals for seabream species. The selection of sites for the replenishment network was based on irreplaceability analyses, while decisions between sites with lower irreplaceability values were based on explicit design rules. A total of 26 sites were required to achieve targets for all species. These replenishment zones could potentially be established, managed and monitored by voluntary community groups. This study therefore indicated that systematic conservation planning can successfully be applied to the marine environment, while the involvement of stakeholders is crucial to ensure that conservation action is supported.
- Full Text:
- Date Issued: 2004
Sobriety of crisp and fuzzy topological spaces
- Authors: Jacot-Guillarmod, Paul
- Date: 2004
- Subjects: Topological spaces , Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5414 , http://hdl.handle.net/10962/d1005228 , Topological spaces , Fuzzy sets
- Description: The objective of this thesis is a survey of crisp and fuzzy sober topological spaces. We begin by examining sobriety of crisp topological spaces. We then extend this to the L- topological case and obtain analogous results and characterizations to those of the crisp case. We then brie y examine semi-sobriety of (L;M)-topological spaces.
- Full Text:
- Date Issued: 2004
- Authors: Jacot-Guillarmod, Paul
- Date: 2004
- Subjects: Topological spaces , Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5414 , http://hdl.handle.net/10962/d1005228 , Topological spaces , Fuzzy sets
- Description: The objective of this thesis is a survey of crisp and fuzzy sober topological spaces. We begin by examining sobriety of crisp topological spaces. We then extend this to the L- topological case and obtain analogous results and characterizations to those of the crisp case. We then brie y examine semi-sobriety of (L;M)-topological spaces.
- Full Text:
- Date Issued: 2004
A statistical evaluation and analysis of mosquito repellent combination
- Authors: Asquith, Ilse Bernadette
- Date: 2004
- Subjects: Mosquitoes -- Control , Insect baits and repellents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10422 , http://hdl.handle.net/10948/d1015732
- Description: The present product development project was aimed at studying the synergism and/or antagonism amongst various known insect repellent actives with the view to formulating a multi-active repellent product with improved properties when compared to current single-active commercial products. Advanced statistical methods were used to identify synergism between individual active substances and to define a formulation as close as possible to the “ideal” formulation. Several mosquito repellent samples were prepared and sent to the South African Bureau of Standards (SABS) in Pretoria to test for their efficiency in repelling mosquitoes. From the results of the repellency tests of the various active combinations, three actives were identified that showed promising signs of synergism. These actives were then studied in further detail to determine their optimum combination. In addition, it was shown that when using a natural flavourant as promoter and incorporating a slow-release agent into formulations for aerosols and lotions, a product is obtained that gives comparable levels of efficiency to current commercial products, but at much reduced levels of active loading. Accelerated stability tests performed on the final combination of the three actives used in the final formulation showed no adverse reactions over a three-week study. These tests shall be repeated once the final application form (lotion, aerosol, etc) and product packing have been decided.
- Full Text:
- Date Issued: 2004
- Authors: Asquith, Ilse Bernadette
- Date: 2004
- Subjects: Mosquitoes -- Control , Insect baits and repellents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10422 , http://hdl.handle.net/10948/d1015732
- Description: The present product development project was aimed at studying the synergism and/or antagonism amongst various known insect repellent actives with the view to formulating a multi-active repellent product with improved properties when compared to current single-active commercial products. Advanced statistical methods were used to identify synergism between individual active substances and to define a formulation as close as possible to the “ideal” formulation. Several mosquito repellent samples were prepared and sent to the South African Bureau of Standards (SABS) in Pretoria to test for their efficiency in repelling mosquitoes. From the results of the repellency tests of the various active combinations, three actives were identified that showed promising signs of synergism. These actives were then studied in further detail to determine their optimum combination. In addition, it was shown that when using a natural flavourant as promoter and incorporating a slow-release agent into formulations for aerosols and lotions, a product is obtained that gives comparable levels of efficiency to current commercial products, but at much reduced levels of active loading. Accelerated stability tests performed on the final combination of the three actives used in the final formulation showed no adverse reactions over a three-week study. These tests shall be repeated once the final application form (lotion, aerosol, etc) and product packing have been decided.
- Full Text:
- Date Issued: 2004
Multiprotocol control of networked home entertainment devices
- Authors: Siebörger, David Robert
- Date: 2004
- Subjects: Home entertainment systems , Home video systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4642 , http://hdl.handle.net/10962/d1006585 , Home entertainment systems , Home video systems
- Description: Networks will soon connect a wide range of computing devices within the home. Amongst those devices will be home entertainment devices. Remote control over the network will be a key application for networked entertainment devices, and requires a protocol for communication understood by both controller and controlled device. Devices capable of communication using multiple control protocols will be compatible with a wider range of controllers than those which implement only one control protocol. This work examines home networks and a number of control protocols. The implementations of the UPnP and AV/C protocols for an AV receiver are described. The issues involved in the concurrent use of multiple control protocols to control a device are considered, possible methods of concurrent control discussed, and a solution which simulates virtual copies of the device is implemented and tested.
- Full Text:
- Date Issued: 2004
- Authors: Siebörger, David Robert
- Date: 2004
- Subjects: Home entertainment systems , Home video systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4642 , http://hdl.handle.net/10962/d1006585 , Home entertainment systems , Home video systems
- Description: Networks will soon connect a wide range of computing devices within the home. Amongst those devices will be home entertainment devices. Remote control over the network will be a key application for networked entertainment devices, and requires a protocol for communication understood by both controller and controlled device. Devices capable of communication using multiple control protocols will be compatible with a wider range of controllers than those which implement only one control protocol. This work examines home networks and a number of control protocols. The implementations of the UPnP and AV/C protocols for an AV receiver are described. The issues involved in the concurrent use of multiple control protocols to control a device are considered, possible methods of concurrent control discussed, and a solution which simulates virtual copies of the device is implemented and tested.
- Full Text:
- Date Issued: 2004
Investigations into the nutritional requirements of juvenile dusky kob, Argyrosomus japonicus (Pisces sciaendae), under ambient culture conditions
- Authors: Daniel, Simon James
- Date: 2004
- Subjects: Argyrosomus -- Nutrition -- Requirements , Sciaenidae -- Nutrition -- Requirements , Fishes -- Food , Fishes -- Growth , Fish culture , Fishes -- Nutrition -- Requirements
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5197 , http://hdl.handle.net/10962/d1002602 , Argyrosomus -- Nutrition -- Requirements , Sciaenidae -- Nutrition -- Requirements , Fishes -- Food , Fishes -- Growth , Fish culture , Fishes -- Nutrition -- Requirements
- Description: The effect of dietary protein, protein and energy ratios, fish meal replacement by Soya bean meal and feeding frequency was investigated on the growth, feed efficiency and body composition, of juvenile dusky kob, Argyrosomus japonicus. The effect of dietary protein levels was investigated by comparing isocaloric diets containing 35, 40, 45 and 55% protein. Dietary protein inclusion level significantly affected specific growth rates, feed efficiency and body composition (in terms of fat deposition) and results show that a minimum of 45% and maximum of 52.3% dietary protein is optimal. The protein and energy requirements were investigated by comparing three protein levels (35,40 and 45%) with three lipid levels (6, 9 and 12%) in a 3x3 factorial design. A diet 45% protein and 9% lipid, with a P: E ratio of29 mglkJ and DE of 15.5 kJ/g resulted in an optimal specific growth rate (1.6± 0.2), feed efficiency (FCR= 1.7±0.44; PER= 1.36) and body composition for A. japonicus. To investigate the effect of partial fish meal replacement by Soya bean meal (SBM) in the diet, 20-50% of the protein from fish meal was substituted by protein from SBM, and were compared with a control diet containing only fish meal. No significant differences in the specific growth rates, feed efficiencies and the body composition were recorded for the fish fed the control diet and for fish fed the 20 and 30% SBM treatments. Results show that up to 30% of the protein from fish meal can be replaced with protein from SBM in the diet of this species. The effect of feeding frequency and gut evacuation time was investigated by comparing four feeding frequencies. Fish were fed to satiation either once, twice, three or four times a day. Feed intake was significantly affected by feeding frequency and fish fed 2, 3 and 4 meals a day ate significantly more food (p< 0.05) than the fish fed one meal a day. No significant differences (p> 0.05) in the specific growth rates, feed efficiencies and body composition were recorded for fish fed 2, 3 and 4 times a day. Feed intake was used to calculate an optimal daily ration and feeding two meals a day resulted in an optimal daily ration of 4% BW/day. A gut evacuation time of 7.25 hours indicates that fish fed twice a day probably had sufficient time to digest their food and evacuate their guts, resulting in the same daily feed intake as fish given 3 and 4 meals a day. Results conclude that under the present experimental conditions, a minimum daily ration of 4% BW/day, fed twice a day (in the morning and evening) is required for optimal growth (SGR= 1.33± 0.1), feed efficiency (FCR= 1.96± 0.4; PER= 1.44± 0.2) and body composition in juvenile dusky kob.
- Full Text:
- Date Issued: 2004
- Authors: Daniel, Simon James
- Date: 2004
- Subjects: Argyrosomus -- Nutrition -- Requirements , Sciaenidae -- Nutrition -- Requirements , Fishes -- Food , Fishes -- Growth , Fish culture , Fishes -- Nutrition -- Requirements
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5197 , http://hdl.handle.net/10962/d1002602 , Argyrosomus -- Nutrition -- Requirements , Sciaenidae -- Nutrition -- Requirements , Fishes -- Food , Fishes -- Growth , Fish culture , Fishes -- Nutrition -- Requirements
- Description: The effect of dietary protein, protein and energy ratios, fish meal replacement by Soya bean meal and feeding frequency was investigated on the growth, feed efficiency and body composition, of juvenile dusky kob, Argyrosomus japonicus. The effect of dietary protein levels was investigated by comparing isocaloric diets containing 35, 40, 45 and 55% protein. Dietary protein inclusion level significantly affected specific growth rates, feed efficiency and body composition (in terms of fat deposition) and results show that a minimum of 45% and maximum of 52.3% dietary protein is optimal. The protein and energy requirements were investigated by comparing three protein levels (35,40 and 45%) with three lipid levels (6, 9 and 12%) in a 3x3 factorial design. A diet 45% protein and 9% lipid, with a P: E ratio of29 mglkJ and DE of 15.5 kJ/g resulted in an optimal specific growth rate (1.6± 0.2), feed efficiency (FCR= 1.7±0.44; PER= 1.36) and body composition for A. japonicus. To investigate the effect of partial fish meal replacement by Soya bean meal (SBM) in the diet, 20-50% of the protein from fish meal was substituted by protein from SBM, and were compared with a control diet containing only fish meal. No significant differences in the specific growth rates, feed efficiencies and the body composition were recorded for the fish fed the control diet and for fish fed the 20 and 30% SBM treatments. Results show that up to 30% of the protein from fish meal can be replaced with protein from SBM in the diet of this species. The effect of feeding frequency and gut evacuation time was investigated by comparing four feeding frequencies. Fish were fed to satiation either once, twice, three or four times a day. Feed intake was significantly affected by feeding frequency and fish fed 2, 3 and 4 meals a day ate significantly more food (p< 0.05) than the fish fed one meal a day. No significant differences (p> 0.05) in the specific growth rates, feed efficiencies and body composition were recorded for fish fed 2, 3 and 4 times a day. Feed intake was used to calculate an optimal daily ration and feeding two meals a day resulted in an optimal daily ration of 4% BW/day. A gut evacuation time of 7.25 hours indicates that fish fed twice a day probably had sufficient time to digest their food and evacuate their guts, resulting in the same daily feed intake as fish given 3 and 4 meals a day. Results conclude that under the present experimental conditions, a minimum daily ration of 4% BW/day, fed twice a day (in the morning and evening) is required for optimal growth (SGR= 1.33± 0.1), feed efficiency (FCR= 1.96± 0.4; PER= 1.44± 0.2) and body composition in juvenile dusky kob.
- Full Text:
- Date Issued: 2004
Design of a performance evaluation tool for multimedia databases with special reference to Oracle
- Authors: Stakemire, Tonia
- Date: 2004
- Subjects: Oracle (Computer file) , Application software -- Evaluation , Database management -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4705 , http://hdl.handle.net/10962/d1015975
- Description: Increased production and use of multimedia data has led to the development of a more advanced Database Management System (DBMS), like an Object Relational Database Management System (ORDBMS). These advanced databases are necessitated by the complexity in structure and the functionality required by multimedia data. Unfortunately, no suitable benchmarks exist with which to test the performance of databases when handling multimedia data. This thesis describes the design of a benchmark to measure the performance of basic functionality found in multimedia databases. The benchmark, called MORD (Multimedia Object Relational Databases), targets Oracle, a well known commercial Object Relational Database Management System (ORDBMS) that can handle multimedia data. Although MORD targets Oracle, it can easily be applied to other Multimedia Database Management System (MMDBMS) as a result of a design that stressed its portability, and simplicity. MORD consists of a database schema, test data, and code to simulate representative queries on multimedia databases. A number of experiments are described that validate MORD and ensure its correct design and that its objectives are met. A by-product of these experiments is an initial understanding of the performance of multimedia databases. The experiments show that with multimedia data the buffer cache should be at least large enough to hold the largest dataset, a bigger block size improves the performance, and turning off logging and caching for bulk loading improves the performance. MORD can be used to compare different ORDBMS or to assist in the configuration of a specific database.
- Full Text:
- Date Issued: 2004
- Authors: Stakemire, Tonia
- Date: 2004
- Subjects: Oracle (Computer file) , Application software -- Evaluation , Database management -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4705 , http://hdl.handle.net/10962/d1015975
- Description: Increased production and use of multimedia data has led to the development of a more advanced Database Management System (DBMS), like an Object Relational Database Management System (ORDBMS). These advanced databases are necessitated by the complexity in structure and the functionality required by multimedia data. Unfortunately, no suitable benchmarks exist with which to test the performance of databases when handling multimedia data. This thesis describes the design of a benchmark to measure the performance of basic functionality found in multimedia databases. The benchmark, called MORD (Multimedia Object Relational Databases), targets Oracle, a well known commercial Object Relational Database Management System (ORDBMS) that can handle multimedia data. Although MORD targets Oracle, it can easily be applied to other Multimedia Database Management System (MMDBMS) as a result of a design that stressed its portability, and simplicity. MORD consists of a database schema, test data, and code to simulate representative queries on multimedia databases. A number of experiments are described that validate MORD and ensure its correct design and that its objectives are met. A by-product of these experiments is an initial understanding of the performance of multimedia databases. The experiments show that with multimedia data the buffer cache should be at least large enough to hold the largest dataset, a bigger block size improves the performance, and turning off logging and caching for bulk loading improves the performance. MORD can be used to compare different ORDBMS or to assist in the configuration of a specific database.
- Full Text:
- Date Issued: 2004
Search algorithms on structured and unstructured data in a large database
- Du Plessis, Mathys Cornelius
- Authors: Du Plessis, Mathys Cornelius
- Date: 2004
- Subjects: Online algorithms , Database searching -- South Africa -- Port Elizabeth , Information retrieval -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11094 , http://hdl.handle.net/10948/d1019681
- Description: This project is concerned with the development of a search algorithm for a large archival database. The Port Elizabeth Genealogical Information System (PEGIS) contains a database consisting of almost 600000 individuals. The standard search algorithms are no longer sufficient to locate individuals in the database. A new algorithm was required that allows searches on any of the words or dates in the database, as well as a means to specify where in the desired record a word should occur. A ranking function of retrieved records was also required. A literature study on the field of Information Retrieval and on algorithms designed specifically for the PEGIS was done. These algorithms were adapted and hybridized to yield a search algorithm that allows for the boolean formulation of queries and the specification of the structure of search words in the desired records. The algorithm ranks retrieved records in assumed relevance to the user. The new algorithms were evaluated with regards to retrieval speed and accuracy and were found to be very effective.
- Full Text:
- Date Issued: 2004
- Authors: Du Plessis, Mathys Cornelius
- Date: 2004
- Subjects: Online algorithms , Database searching -- South Africa -- Port Elizabeth , Information retrieval -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11094 , http://hdl.handle.net/10948/d1019681
- Description: This project is concerned with the development of a search algorithm for a large archival database. The Port Elizabeth Genealogical Information System (PEGIS) contains a database consisting of almost 600000 individuals. The standard search algorithms are no longer sufficient to locate individuals in the database. A new algorithm was required that allows searches on any of the words or dates in the database, as well as a means to specify where in the desired record a word should occur. A ranking function of retrieved records was also required. A literature study on the field of Information Retrieval and on algorithms designed specifically for the PEGIS was done. These algorithms were adapted and hybridized to yield a search algorithm that allows for the boolean formulation of queries and the specification of the structure of search words in the desired records. The algorithm ranks retrieved records in assumed relevance to the user. The new algorithms were evaluated with regards to retrieval speed and accuracy and were found to be very effective.
- Full Text:
- Date Issued: 2004
The effect of diet type and feeding rate on growth, morphological development and behaviour of larval and juvenile goldfish Carassius auratus (L.)
- Authors: Paulet, Timothy Guy
- Date: 2004
- Subjects: Goldfish -- Growth , Goldfish -- Nutrition , Goldfish -- Development , Goldfish -- Larvae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5271 , http://hdl.handle.net/10962/d1005115 , Goldfish -- Growth , Goldfish -- Nutrition , Goldfish -- Development , Goldfish -- Larvae
- Description: Intensive grow-out of goldfish, Carassius auratus (L.), larvae and juveniles in closed recirculating systems requires the control of environmental conditions and feeding. This study investigated the effect of different diets, environmental condition and feeding level on growth, development and survival of goldfish larvae and juveniles. Prey preference for Artemia nauplii or decapsulated Artemia cysts as well as agonistic behaviour was recorded. The micrometer device used to measure mouth-gape was shown to produce accurate measurements which could be used to estimate the maximal particle size that can be ingested by goldfish larvae of a particular age. Goldfish completed metamorphosis earlier with an increased feeding level of Artemia cysts and by making the cysts more accessible to the fish using up-welling water movement. Morphometric plasticity in goldfish larvae was exhibited within two weeks of growth and it may be possible to induce changes in morphology by manipulating diet and rearing environment. Fish that fed on moving prey items had a significantly larger mouth-gape than those that browsed cysts from the tank bottom or dry food items. The development of mouth-gape was not affected by the feeding level of cysts. Condition factor increased with an increase in the number of cysts fed per fish per day. Goldfish larvae and juveniles grew faster and had a higher survival when fed on decapsulated Artemia cysts than on instar I Artemia nauplii or a mixed live/dry diet of Artemia nauplii and dry food. Feeding at least 155 cysts per fish per day, in tanks with upwelling water movement, gave the best growth and survival and the smallest size variation. In addition, cysts remained available to the fish for longer periods, and were easier to prepare and feed. Goldfish larvae preferred decapsulated Artemia cysts to nauplii and rejected fewer prey items as they grew older. The frequency of agonistic behaviour increased as fish grew but no cannibalism was recorded for cyst-fed fish. This study showed that decapsulated Artemia cysts are a good alternative to Artemia nauplii as a diet for larval goldfish. Good growth and high survival was achieved for cyst-fed goldfish larvae and juveniles at 23 ± 1.5°C and at an initial stocking density of 12 fish per litre. This research also contributes to an understanding of feeding behaviour and attempts to minimise under- or over-feeding of Artemia cysts in order to reduce grow-out costs due to the high value of the feed type.
- Full Text:
- Date Issued: 2004
- Authors: Paulet, Timothy Guy
- Date: 2004
- Subjects: Goldfish -- Growth , Goldfish -- Nutrition , Goldfish -- Development , Goldfish -- Larvae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5271 , http://hdl.handle.net/10962/d1005115 , Goldfish -- Growth , Goldfish -- Nutrition , Goldfish -- Development , Goldfish -- Larvae
- Description: Intensive grow-out of goldfish, Carassius auratus (L.), larvae and juveniles in closed recirculating systems requires the control of environmental conditions and feeding. This study investigated the effect of different diets, environmental condition and feeding level on growth, development and survival of goldfish larvae and juveniles. Prey preference for Artemia nauplii or decapsulated Artemia cysts as well as agonistic behaviour was recorded. The micrometer device used to measure mouth-gape was shown to produce accurate measurements which could be used to estimate the maximal particle size that can be ingested by goldfish larvae of a particular age. Goldfish completed metamorphosis earlier with an increased feeding level of Artemia cysts and by making the cysts more accessible to the fish using up-welling water movement. Morphometric plasticity in goldfish larvae was exhibited within two weeks of growth and it may be possible to induce changes in morphology by manipulating diet and rearing environment. Fish that fed on moving prey items had a significantly larger mouth-gape than those that browsed cysts from the tank bottom or dry food items. The development of mouth-gape was not affected by the feeding level of cysts. Condition factor increased with an increase in the number of cysts fed per fish per day. Goldfish larvae and juveniles grew faster and had a higher survival when fed on decapsulated Artemia cysts than on instar I Artemia nauplii or a mixed live/dry diet of Artemia nauplii and dry food. Feeding at least 155 cysts per fish per day, in tanks with upwelling water movement, gave the best growth and survival and the smallest size variation. In addition, cysts remained available to the fish for longer periods, and were easier to prepare and feed. Goldfish larvae preferred decapsulated Artemia cysts to nauplii and rejected fewer prey items as they grew older. The frequency of agonistic behaviour increased as fish grew but no cannibalism was recorded for cyst-fed fish. This study showed that decapsulated Artemia cysts are a good alternative to Artemia nauplii as a diet for larval goldfish. Good growth and high survival was achieved for cyst-fed goldfish larvae and juveniles at 23 ± 1.5°C and at an initial stocking density of 12 fish per litre. This research also contributes to an understanding of feeding behaviour and attempts to minimise under- or over-feeding of Artemia cysts in order to reduce grow-out costs due to the high value of the feed type.
- Full Text:
- Date Issued: 2004
Synthesis and evaluation of PGM-selective ligands
- Gxoyiya, Babalwa Siliziwe Blossom
- Authors: Gxoyiya, Babalwa Siliziwe Blossom
- Date: 2013-05-28
- Subjects: Platinum group , Ligands , Ligands -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4450 , http://hdl.handle.net/10962/d1007849 , Platinum group , Ligands , Ligands -- Evaluation
- Description: A series of polydentate POM-selective, sulfur-containing amide ligands have been synthesized from ro-dibromoalkanes and mercaptoacetanilide, The resulting 3,6- dithiaoctanediamides and 3,7-dithianonanediamides, some of which contain a polymerisable group, were all characterized by high-resolution MS, IR, I Hand I3C NMR spectroscopic methods. Various approaches to the polymerisable ligands were explored, the most efficient proving to be the incorporation of an allyl ether moiety in the mercaptoacetanilide. The corresponding Pd(U) and Pt(II) complexes were also prepared from the metal chloride salts and characterized by elemental analysis and spectroscopic methods. The NMR data indicates that both the cis- and transcomplexes were formed, while the IR data indicates cis- coordination of the chlorine . ligands. Molecularly imprinted polymers (MIP's), prepared using platinum(II) mercaptoacetanilide and 3,6-dithiadiamide complexes, showed high selectivity for , , palladium(II) [in the presence of Pt(II), CoCII), Cu(II) and Ni(II)] as determined by . ICP-MS analysis. The more kinetically inert Pt(II) ions however, slowly displaced Pd(II), confirming the Pt(II) selectivity of the MIP's. Solvent extraction studies were conducted to explore the selectivity of the 3,6- dithiaoctanediamides and 3,7-dithianonanediamides for Pd(U) over CoCII), Cu(U) and Ni(II). The ICP-MS data indicate that, in general, equilibration was achieved within ten minutes and that the longer-chain amides were less selective than the shorter-chain analogues. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Authors: Gxoyiya, Babalwa Siliziwe Blossom
- Date: 2013-05-28
- Subjects: Platinum group , Ligands , Ligands -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4450 , http://hdl.handle.net/10962/d1007849 , Platinum group , Ligands , Ligands -- Evaluation
- Description: A series of polydentate POM-selective, sulfur-containing amide ligands have been synthesized from ro-dibromoalkanes and mercaptoacetanilide, The resulting 3,6- dithiaoctanediamides and 3,7-dithianonanediamides, some of which contain a polymerisable group, were all characterized by high-resolution MS, IR, I Hand I3C NMR spectroscopic methods. Various approaches to the polymerisable ligands were explored, the most efficient proving to be the incorporation of an allyl ether moiety in the mercaptoacetanilide. The corresponding Pd(U) and Pt(II) complexes were also prepared from the metal chloride salts and characterized by elemental analysis and spectroscopic methods. The NMR data indicates that both the cis- and transcomplexes were formed, while the IR data indicates cis- coordination of the chlorine . ligands. Molecularly imprinted polymers (MIP's), prepared using platinum(II) mercaptoacetanilide and 3,6-dithiadiamide complexes, showed high selectivity for , , palladium(II) [in the presence of Pt(II), CoCII), Cu(II) and Ni(II)] as determined by . ICP-MS analysis. The more kinetically inert Pt(II) ions however, slowly displaced Pd(II), confirming the Pt(II) selectivity of the MIP's. Solvent extraction studies were conducted to explore the selectivity of the 3,6- dithiaoctanediamides and 3,7-dithianonanediamides for Pd(U) over CoCII), Cu(U) and Ni(II). The ICP-MS data indicate that, in general, equilibration was achieved within ten minutes and that the longer-chain amides were less selective than the shorter-chain analogues. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
CREWS : a Component-driven, Run-time Extensible Web Service framework
- Authors: Parry, Dominic Charles
- Date: 2004
- Subjects: Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4628 , http://hdl.handle.net/10962/d1006501 , Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Description: There has been an increased focus in recent years on the development of re-usable software, in the form of objects and software components. This increase, together with pressures from enterprises conducting transactions on the Web to support all business interactions on all scales, has encouraged research towards the development of easily reconfigurable and highly adaptable Web services. This work investigates the ability of Component-Based Software Development (CBSD) to produce such systems, and proposes a more manageable use of CBSD methodologies. Component-Driven Software Development (CDSD) is introduced to enable better component manageability. Current Web service technologies are also examined to determine their ability to support extensible Web services, and a dynamic Web service architecture is proposed. The work also describes the development of two proof-of-concept systems, DREW Chat and Hamilton Bank. DREW Chat and Hamilton Bank are implementations of Web services that support extension dynamically and at run-time. DREW Chat is implemented on the client side, where the user is given the ability to change the client as required. Hamilton Bank is a server-side implementation, which is run-time customisable by both the user and the party offering the service. In each case, a generic architecture is produced to support dynamic Web services. These architectures are combined to produce CREWS, a Component-driven Runtime Extensible Web Service solution that enables Web services to support the ever changing needs of enterprises. A discussion of similar work is presented, identifying the strengths and weaknesses of our architecture when compared to other solutions.
- Full Text:
- Date Issued: 2004
- Authors: Parry, Dominic Charles
- Date: 2004
- Subjects: Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4628 , http://hdl.handle.net/10962/d1006501 , Component software -- Development , Computer software -- Reusability , Software reengineering , Web services
- Description: There has been an increased focus in recent years on the development of re-usable software, in the form of objects and software components. This increase, together with pressures from enterprises conducting transactions on the Web to support all business interactions on all scales, has encouraged research towards the development of easily reconfigurable and highly adaptable Web services. This work investigates the ability of Component-Based Software Development (CBSD) to produce such systems, and proposes a more manageable use of CBSD methodologies. Component-Driven Software Development (CDSD) is introduced to enable better component manageability. Current Web service technologies are also examined to determine their ability to support extensible Web services, and a dynamic Web service architecture is proposed. The work also describes the development of two proof-of-concept systems, DREW Chat and Hamilton Bank. DREW Chat and Hamilton Bank are implementations of Web services that support extension dynamically and at run-time. DREW Chat is implemented on the client side, where the user is given the ability to change the client as required. Hamilton Bank is a server-side implementation, which is run-time customisable by both the user and the party offering the service. In each case, a generic architecture is produced to support dynamic Web services. These architectures are combined to produce CREWS, a Component-driven Runtime Extensible Web Service solution that enables Web services to support the ever changing needs of enterprises. A discussion of similar work is presented, identifying the strengths and weaknesses of our architecture when compared to other solutions.
- Full Text:
- Date Issued: 2004
The feeding biology and potential impact of introduced giraffe (Giraffa camelopardalis) in the Eastern Cape Province, South Africa
- Authors: Parker, Daniel Matthew
- Date: 2004
- Subjects: Giraffe -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5694 , http://hdl.handle.net/10962/d1005380
- Description: Giraffe (Giraffa camelopardalis) are extralimital (non-native) to the Eastern Cape Province, South Africa yet they have and continue to be introduced to the region. Financial gain has arguably been the driving force behind these introductions as foreign tourists associate giraffe with Africa and the African wildlife experience. This raises a number of ethical, ecological and philosophical questions especially when it is considered that the impact of these browsers on the indigenous vegetation has remained largely unquantified. In this study I assessed the diet and potential impact of three populations of giraffe in the Eastern Cape Province between January 2002 and October 2003. The diet was assessed by both direct observations and faecal analysis. There was no significant difference (P > 0.05) between the results of the two methods of analysis, although direct observations appeared to be a superior method for assessing the diet of giraffe. The diet of giraffe in the Eastern Cape Province was similar to that within their native range with a deciduous species from the genus Acacia (Acacia karroo) being the most important component of the diet. However, giraffe in the Eastern Cape Province consumed more evergreen plant species than those within their native range. The relative lack of deciduous species in the Eastern Cape Province provides a likely explanation for such a result. Seasonal variation in the consumption of the most important species in the diet was evident and this was attributed to the deciduous nature of A. karroo and the seasonal growth of new shoots which were more palatable. The vegetation of the areas most commonly utilised by giraffe at each site was sampled using the point-centred-quarter method and the results related to the frequency of each species in the diet to calculate preference indices. Giraffe preference was strongest for A. karroo and this was attributed to the highly favourable chemical composition of the species. The browse utilisation of giraffe at each site was determined using the twig-length method and intake rates for the three most important species in the diet calculated using a pre-existing regression equation. Male giraffe fed at a higher rate than females. This was probably due to males adopting a “time-minimising” strategy to their feeding in order to allow more time for reproductive pursuits. Giraffe browse utilisation was highest where giraffe density was highest. However, several species were more heavily browsed than others even when giraffe density was low, suggesting that giraffe are capable of negatively affecting the indigenous flora of the province. I conclude that giraffe numbers should be reduced relative to property size in the Eastern Cape Province and that research into the impact of not only giraffe but the combined effects of giraffe and other extralimital herbivores on the indigenous flora and fauna be continued.
- Full Text:
- Date Issued: 2004
- Authors: Parker, Daniel Matthew
- Date: 2004
- Subjects: Giraffe -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5694 , http://hdl.handle.net/10962/d1005380
- Description: Giraffe (Giraffa camelopardalis) are extralimital (non-native) to the Eastern Cape Province, South Africa yet they have and continue to be introduced to the region. Financial gain has arguably been the driving force behind these introductions as foreign tourists associate giraffe with Africa and the African wildlife experience. This raises a number of ethical, ecological and philosophical questions especially when it is considered that the impact of these browsers on the indigenous vegetation has remained largely unquantified. In this study I assessed the diet and potential impact of three populations of giraffe in the Eastern Cape Province between January 2002 and October 2003. The diet was assessed by both direct observations and faecal analysis. There was no significant difference (P > 0.05) between the results of the two methods of analysis, although direct observations appeared to be a superior method for assessing the diet of giraffe. The diet of giraffe in the Eastern Cape Province was similar to that within their native range with a deciduous species from the genus Acacia (Acacia karroo) being the most important component of the diet. However, giraffe in the Eastern Cape Province consumed more evergreen plant species than those within their native range. The relative lack of deciduous species in the Eastern Cape Province provides a likely explanation for such a result. Seasonal variation in the consumption of the most important species in the diet was evident and this was attributed to the deciduous nature of A. karroo and the seasonal growth of new shoots which were more palatable. The vegetation of the areas most commonly utilised by giraffe at each site was sampled using the point-centred-quarter method and the results related to the frequency of each species in the diet to calculate preference indices. Giraffe preference was strongest for A. karroo and this was attributed to the highly favourable chemical composition of the species. The browse utilisation of giraffe at each site was determined using the twig-length method and intake rates for the three most important species in the diet calculated using a pre-existing regression equation. Male giraffe fed at a higher rate than females. This was probably due to males adopting a “time-minimising” strategy to their feeding in order to allow more time for reproductive pursuits. Giraffe browse utilisation was highest where giraffe density was highest. However, several species were more heavily browsed than others even when giraffe density was low, suggesting that giraffe are capable of negatively affecting the indigenous flora of the province. I conclude that giraffe numbers should be reduced relative to property size in the Eastern Cape Province and that research into the impact of not only giraffe but the combined effects of giraffe and other extralimital herbivores on the indigenous flora and fauna be continued.
- Full Text:
- Date Issued: 2004
A comparative study of the Linux and windows device driver architecture with a focus on IEEE1394 (high speed serial bus) drivers
- Authors: Tsegaye, Melekam Asrat
- Date: 2004
- Subjects: Microsoft Windows (Computer file) , Linux , Operating systems (Computers) , DOS device drivers (Computer programs) , Linux device drivers (Computer programs)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4591 , http://hdl.handle.net/10962/d1004829 , Microsoft Windows (Computer file) , Linux , Operating systems (Computers) , DOS device drivers (Computer programs) , Linux device drivers (Computer programs)
- Description: New hardware devices are continually being released to the public by hardware manufactures around the world. For these new devices to be usable under a PC operating system, device drivers that extend the functionality of the target operating system have to be constructed. This work examines and compares the device driver architectures currently in use by two of the most widely used operating systems, Microsoft’s Windows and Linux. The IEEE1394 (high speed serial bus) device driver stacks on each operating system are examined and compared as an example of a major device driver stack implementation, including driver requirements for the upcoming IEEE1394.1 bridging standard.
- Full Text:
- Date Issued: 2004
- Authors: Tsegaye, Melekam Asrat
- Date: 2004
- Subjects: Microsoft Windows (Computer file) , Linux , Operating systems (Computers) , DOS device drivers (Computer programs) , Linux device drivers (Computer programs)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4591 , http://hdl.handle.net/10962/d1004829 , Microsoft Windows (Computer file) , Linux , Operating systems (Computers) , DOS device drivers (Computer programs) , Linux device drivers (Computer programs)
- Description: New hardware devices are continually being released to the public by hardware manufactures around the world. For these new devices to be usable under a PC operating system, device drivers that extend the functionality of the target operating system have to be constructed. This work examines and compares the device driver architectures currently in use by two of the most widely used operating systems, Microsoft’s Windows and Linux. The IEEE1394 (high speed serial bus) device driver stacks on each operating system are examined and compared as an example of a major device driver stack implementation, including driver requirements for the upcoming IEEE1394.1 bridging standard.
- Full Text:
- Date Issued: 2004
Biochemical characterization of plasmodium falciparum heat shock protein 70
- Matambo, Tonderayi Sylvester
- Authors: Matambo, Tonderayi Sylvester
- Date: 2004
- Subjects: Plasmodium falciparum , Malaria -- Prevention , Protein folding , Proteins -- Purification , Heat shock proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4134 , http://hdl.handle.net/10962/d1015767
- Description: Plamodium falciparum heat shock protein (PfHsp70) is believed to be involved in the cytoprotection of the malaria parasite through its action as a molecular chaperone. Bioinformatic analysis reveal that PfHsp70 consists of the three canonical Hsp70 domains; an ATPase domain of 45 kDa, Substrate binding domain of 15 kDa and a C-terminal domain of 10 kDa. At the C-terminus there is a GGMP repeat motif that is commonly found in Hsp70s of parasitic origins. Plasmodium falciparum genome is 80% A-T rich, making it difficult to recombinantly express its proteins in Escherhia coli (E. coli) as a result of rare codon usage. In this study we carried out experiments to improve expression in E. coli by inserting the PfHsp70 coding region into the pQE30 expression vector. However multiple bands were detected by Western analysis, probably due to the presence of rare codons. The RIG plasmid, which encodes tRNAs for rare codons in particular Arg (AGA/AGG), Ile (AUA) and Gly (GGA) was engineered into the E. coli strain resulting in production of full length PfHsp70. Purification was achieved through Ni²⁺ Chelating sepharose under denaturing conditions. PfHsp70 was found to have a very low basal ATPase activity of 0.262 ± 0.05 nmoles/min/mg of protein. In the presence of reduced and carboxymethylated lactalbumin (RCMLA) a 11-fold increase in ATPase activity was noted whereas in the presence of both RCMLA and Trypanosoma cruzi DnaJ (Tcj2) a 16-fold was achieved. For ATP hydrolysis kcat value of 0.003 min⁻¹ was obtained whereas for ADP release a greater kcat value of 0.8 min⁻¹ was obtained. These results indicated that rate of ATP hydrolysis maybe the rate-determining step in the ATPase cycle of PfHsp70.
- Full Text:
- Date Issued: 2004
- Authors: Matambo, Tonderayi Sylvester
- Date: 2004
- Subjects: Plasmodium falciparum , Malaria -- Prevention , Protein folding , Proteins -- Purification , Heat shock proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4134 , http://hdl.handle.net/10962/d1015767
- Description: Plamodium falciparum heat shock protein (PfHsp70) is believed to be involved in the cytoprotection of the malaria parasite through its action as a molecular chaperone. Bioinformatic analysis reveal that PfHsp70 consists of the three canonical Hsp70 domains; an ATPase domain of 45 kDa, Substrate binding domain of 15 kDa and a C-terminal domain of 10 kDa. At the C-terminus there is a GGMP repeat motif that is commonly found in Hsp70s of parasitic origins. Plasmodium falciparum genome is 80% A-T rich, making it difficult to recombinantly express its proteins in Escherhia coli (E. coli) as a result of rare codon usage. In this study we carried out experiments to improve expression in E. coli by inserting the PfHsp70 coding region into the pQE30 expression vector. However multiple bands were detected by Western analysis, probably due to the presence of rare codons. The RIG plasmid, which encodes tRNAs for rare codons in particular Arg (AGA/AGG), Ile (AUA) and Gly (GGA) was engineered into the E. coli strain resulting in production of full length PfHsp70. Purification was achieved through Ni²⁺ Chelating sepharose under denaturing conditions. PfHsp70 was found to have a very low basal ATPase activity of 0.262 ± 0.05 nmoles/min/mg of protein. In the presence of reduced and carboxymethylated lactalbumin (RCMLA) a 11-fold increase in ATPase activity was noted whereas in the presence of both RCMLA and Trypanosoma cruzi DnaJ (Tcj2) a 16-fold was achieved. For ATP hydrolysis kcat value of 0.003 min⁻¹ was obtained whereas for ADP release a greater kcat value of 0.8 min⁻¹ was obtained. These results indicated that rate of ATP hydrolysis maybe the rate-determining step in the ATPase cycle of PfHsp70.
- Full Text:
- Date Issued: 2004
Towards sustainable utilisation of the fishery resources of the Kowie Estuary, South Africa
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2004
- Subjects: Estuarine fisheries -- South Africa -- Eastern Cape -- Kowie Estuary , Estuarine ecology -- South Africa -- Eastern Cape -- Kowie Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4761 , http://hdl.handle.net/10962/d1007154 , Estuarine fisheries -- South Africa -- Eastern Cape -- Kowie Estuary , Estuarine ecology -- South Africa -- Eastern Cape -- Kowie Estuary
- Description: The annual biomass of fish caught from estuaries in South Africa is currently estimated at over 24,800 tons. These estuarine fishes are caught by over 73,000 fishers, most of them recreational. Annual income derived from South Africa’s total estuarine fishery was worth approximately R430,000,000 in 1997. There is increasing concern that unless our estuarine fisheries are effectively managed, we will not be able to sustain these benefits into the future. Two factors that contribute to inadequate management of the estuarine fisheries in South Africa are a lack of data on which to base management decisions, and the lack of indicators by which to assess trends towards sustainability. The main aims of this study were to provide a description of the Kowie estuary fishery, identify suitable indicators of sustainability for this fishery, and assess its sustainability. Boat-based and shore-based roving creel surveys were carried out on the Kowie estuary between July 2000 and June 2001; 1,091 interviews were conducted with linefishers, and 277 interviews with bait collectors. In the boat-based interviews, data were collected on fisher demographics, fishing site, fishing method, choice of bait, fishing duration and catch statistics. In the shore-based surveys, additional data were collected from shore-based linefishers and bait collectors on their perceptions, attitudes, and knowledge of fishery regulations. Total annual fishing effort on the Kowie estuary was estimated at 30,952 angler hours (SD=154); 84% of it recreational, and the rest subsistence. Most fishing occurred during December and January, and decreased during winter, especially June and July. The annual yield of fish from the estuary was estimated at 16,240 fish (SD=667) or 5.99 tons (SD=0.81). By number, recreational anglers caught 69% of the annual catch. Three species dominated the catch by number: Rhabdosargus holubi (62%), Pomadasys commersonnii (17%) and Argyrosomus japonicus (7%). By mass, the dominant species caught were Argyrosomus japonicus (60%) and Pomadasys commersonnii (19%). Overall catch rate on the estuary was 0.57 fish.ang.⁻¹h⁻¹ (SD=0.24), or 0.298 kg ang.⁻¹h⁻¹ (SD=0.31). Overall catch rate by number was highest in the subsistence sector at 1.13 fish.ang.⁻¹h⁻¹(SD=0.70), while the boat-based recreational sector recorded the highest overall catch rate by mass (0.427 kg.ang.⁻¹h⁻¹, SD=0.625). Argyrosomus japonicus had the highest overall catch rate by mass on the estuary (0.496 kg ang.⁻¹h⁻¹), and Rhabdosargus holubi the highest overall catch rate by number (1.233 fish.ang.⁻¹h⁻¹). Only 19% of the catch of R. holubi was above the minimum legal size, while the estimates for P. commersonnii and A. japonicus were 21% and 25%, respectively. The annual number of bait collecting outings on the estuary was estimated at 2,889, of which 75% were subsistence. The highest numbers of bait collecting outings were recorded in December and April. The Bay of Biscay was the most popular site for bait collecting. A total of five invertebrate species were collected from the estuary to be used as bait, of which the mud prawn Upogebia africana was the dominant species. Total annual number of mud prawns collected from the estuary was estimated at 260,648; of which 41% was collected by subsistence bait collectors. Thirteen indicators were selected to assess sustainability in three fishery sectors on the Kowie estuary: namely, the shore-based recreational linefishery, the subsistence linefishery and the subsistence bait fishery. Social sustainability was evaluated on the basis of the use fishery resources to fulfil Maslow's basic human needs of food and employment, safety and security, affiliation, self-esteem and selfactualisation. Indicators of ecosystem sustainability assessed the productivity, diversity, disturbance and degree of water quality in the estuary. Institutional sustainability was assessed on the basis that management systems in the fishery should be results-oriented, consent-based, truth-seeking and adaptable. Data on indicator performance was collected during the shore-based roving creel survey, and from published literature. Arbitrarily set reference points were used to assess indicator performance, which was graded on a scale from 1 (indicating minimum probability of sustainability) to 4 (indicating maximum probability of sustainability). Sustainability was illustrated with the aid of amoeba plots. Overall sustainability was low in all three fishery sectors investigated. Nine of the 13 indicators in the shore-based recreational fishery performed poorly, while 11 of 13 in the subsistence line fishery, and 10 of 13 in the subsistence bait fishery, performed poorly. In all three fishery sectors all four selected indicators of institutional sustainability performed poorly. The probability of social sustainability was higher in the shore-based recreational line fishery, where the performance of two of the five selected indicators was very good. The probability of ecological sustainability was lowest in the shore-based recreational linefishery, while in the subsistence linefishery only one selected indicator performed very well. Recommendations made towards assessing sustainability in small-scale estuarine fisheries include the formulation of national policy for assessing sustainability in fisheries, the involvement of fishers in the assessment process, use of fisher perceptions where data gaps exist, and the use of research results to guide future management decisions. Management changes recommended for the Kowie estuary fishery include the formulation of an effective and integrated management plan, identification of the key stakeholders in the fishery, inclusion of fishers in management, the protection of the estuary’s Zostera capensis beds, and the establishment of a programme to increase research and monitoring in the fishery.
- Full Text:
- Date Issued: 2004
- Authors: Nsubuga, Yvonne Nakalo
- Date: 2004
- Subjects: Estuarine fisheries -- South Africa -- Eastern Cape -- Kowie Estuary , Estuarine ecology -- South Africa -- Eastern Cape -- Kowie Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4761 , http://hdl.handle.net/10962/d1007154 , Estuarine fisheries -- South Africa -- Eastern Cape -- Kowie Estuary , Estuarine ecology -- South Africa -- Eastern Cape -- Kowie Estuary
- Description: The annual biomass of fish caught from estuaries in South Africa is currently estimated at over 24,800 tons. These estuarine fishes are caught by over 73,000 fishers, most of them recreational. Annual income derived from South Africa’s total estuarine fishery was worth approximately R430,000,000 in 1997. There is increasing concern that unless our estuarine fisheries are effectively managed, we will not be able to sustain these benefits into the future. Two factors that contribute to inadequate management of the estuarine fisheries in South Africa are a lack of data on which to base management decisions, and the lack of indicators by which to assess trends towards sustainability. The main aims of this study were to provide a description of the Kowie estuary fishery, identify suitable indicators of sustainability for this fishery, and assess its sustainability. Boat-based and shore-based roving creel surveys were carried out on the Kowie estuary between July 2000 and June 2001; 1,091 interviews were conducted with linefishers, and 277 interviews with bait collectors. In the boat-based interviews, data were collected on fisher demographics, fishing site, fishing method, choice of bait, fishing duration and catch statistics. In the shore-based surveys, additional data were collected from shore-based linefishers and bait collectors on their perceptions, attitudes, and knowledge of fishery regulations. Total annual fishing effort on the Kowie estuary was estimated at 30,952 angler hours (SD=154); 84% of it recreational, and the rest subsistence. Most fishing occurred during December and January, and decreased during winter, especially June and July. The annual yield of fish from the estuary was estimated at 16,240 fish (SD=667) or 5.99 tons (SD=0.81). By number, recreational anglers caught 69% of the annual catch. Three species dominated the catch by number: Rhabdosargus holubi (62%), Pomadasys commersonnii (17%) and Argyrosomus japonicus (7%). By mass, the dominant species caught were Argyrosomus japonicus (60%) and Pomadasys commersonnii (19%). Overall catch rate on the estuary was 0.57 fish.ang.⁻¹h⁻¹ (SD=0.24), or 0.298 kg ang.⁻¹h⁻¹ (SD=0.31). Overall catch rate by number was highest in the subsistence sector at 1.13 fish.ang.⁻¹h⁻¹(SD=0.70), while the boat-based recreational sector recorded the highest overall catch rate by mass (0.427 kg.ang.⁻¹h⁻¹, SD=0.625). Argyrosomus japonicus had the highest overall catch rate by mass on the estuary (0.496 kg ang.⁻¹h⁻¹), and Rhabdosargus holubi the highest overall catch rate by number (1.233 fish.ang.⁻¹h⁻¹). Only 19% of the catch of R. holubi was above the minimum legal size, while the estimates for P. commersonnii and A. japonicus were 21% and 25%, respectively. The annual number of bait collecting outings on the estuary was estimated at 2,889, of which 75% were subsistence. The highest numbers of bait collecting outings were recorded in December and April. The Bay of Biscay was the most popular site for bait collecting. A total of five invertebrate species were collected from the estuary to be used as bait, of which the mud prawn Upogebia africana was the dominant species. Total annual number of mud prawns collected from the estuary was estimated at 260,648; of which 41% was collected by subsistence bait collectors. Thirteen indicators were selected to assess sustainability in three fishery sectors on the Kowie estuary: namely, the shore-based recreational linefishery, the subsistence linefishery and the subsistence bait fishery. Social sustainability was evaluated on the basis of the use fishery resources to fulfil Maslow's basic human needs of food and employment, safety and security, affiliation, self-esteem and selfactualisation. Indicators of ecosystem sustainability assessed the productivity, diversity, disturbance and degree of water quality in the estuary. Institutional sustainability was assessed on the basis that management systems in the fishery should be results-oriented, consent-based, truth-seeking and adaptable. Data on indicator performance was collected during the shore-based roving creel survey, and from published literature. Arbitrarily set reference points were used to assess indicator performance, which was graded on a scale from 1 (indicating minimum probability of sustainability) to 4 (indicating maximum probability of sustainability). Sustainability was illustrated with the aid of amoeba plots. Overall sustainability was low in all three fishery sectors investigated. Nine of the 13 indicators in the shore-based recreational fishery performed poorly, while 11 of 13 in the subsistence line fishery, and 10 of 13 in the subsistence bait fishery, performed poorly. In all three fishery sectors all four selected indicators of institutional sustainability performed poorly. The probability of social sustainability was higher in the shore-based recreational line fishery, where the performance of two of the five selected indicators was very good. The probability of ecological sustainability was lowest in the shore-based recreational linefishery, while in the subsistence linefishery only one selected indicator performed very well. Recommendations made towards assessing sustainability in small-scale estuarine fisheries include the formulation of national policy for assessing sustainability in fisheries, the involvement of fishers in the assessment process, use of fisher perceptions where data gaps exist, and the use of research results to guide future management decisions. Management changes recommended for the Kowie estuary fishery include the formulation of an effective and integrated management plan, identification of the key stakeholders in the fishery, inclusion of fishers in management, the protection of the estuary’s Zostera capensis beds, and the establishment of a programme to increase research and monitoring in the fishery.
- Full Text:
- Date Issued: 2004