Human agency and development: re-politicizing human development
- Authors: Ncube, Moreblessings
- Date: 2008
- Subjects: Political participation , Agent (Philosophy) , Citizenship
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26625 , vital:65680
- Description: This thesis presents a value-laden understanding of development that acknowledges that development is human centered. The study re-emphasizes that human development which has become a powerful element of current development discourse is not just a social, economic and technological challenge; it is also an institutional and political challenge. The study therefore analyzes the notion of human development with the intention of improving it by placing more emphasis on the aspect of politics and human agency the ability to act and be an agent of ones life. Politics here is understood beyond its usual institutional focus or identification with government, politicians and parliaments to include a much wider and much more important and dynamic range of activities found in all human groups such as institutions and societies. The study then demonstrates that since development is a process, individuals need to work collectively towards a common good so as to realize their development potential. This means creating a confederation of development where governments, citizens and non-governmental organizations work in partnership guided by a culture of collectiveness civic culture in order to produce more empowered citizens. The major argument in this study is the concern for citizens to effectively participate in areas that affect and impact on their lives and consequently be in a position to hold accountable institutions that affect their decision making capabilities. Hence human agency in this study signifies and can be justified as an important aspect of the process of participation leading to empowerment. , Thesis (PhD) -- Faculty of Management and Commerce, 2008
- Full Text:
- Date Issued: 2008
- Authors: Ncube, Moreblessings
- Date: 2008
- Subjects: Political participation , Agent (Philosophy) , Citizenship
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/26625 , vital:65680
- Description: This thesis presents a value-laden understanding of development that acknowledges that development is human centered. The study re-emphasizes that human development which has become a powerful element of current development discourse is not just a social, economic and technological challenge; it is also an institutional and political challenge. The study therefore analyzes the notion of human development with the intention of improving it by placing more emphasis on the aspect of politics and human agency the ability to act and be an agent of ones life. Politics here is understood beyond its usual institutional focus or identification with government, politicians and parliaments to include a much wider and much more important and dynamic range of activities found in all human groups such as institutions and societies. The study then demonstrates that since development is a process, individuals need to work collectively towards a common good so as to realize their development potential. This means creating a confederation of development where governments, citizens and non-governmental organizations work in partnership guided by a culture of collectiveness civic culture in order to produce more empowered citizens. The major argument in this study is the concern for citizens to effectively participate in areas that affect and impact on their lives and consequently be in a position to hold accountable institutions that affect their decision making capabilities. Hence human agency in this study signifies and can be justified as an important aspect of the process of participation leading to empowerment. , Thesis (PhD) -- Faculty of Management and Commerce, 2008
- Full Text:
- Date Issued: 2008
Reactor development and process optimisation for the bioremediation of phenolic wastewaters by trametes species
- Authors: Ryan, Daniel Reginald
- Date: 2004-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191487 , vital:45103
- Description: In many service industries, the source of a company’s value has shifted from capital to knowledge and ideas, the quality of which is dependent on its employees (Wooldridge, 2006). In fact, human resources can be considered part of factor conditions which can positively impact on a firm’s competitive context. This impact can ultimately translate into improved financial results (Porter and Kramer, 2002). There is therefore a growing interest in ways to attract and retain talent. According to the managers of many big companies, well communicated corporate responsibility practices can improve staff attraction as well as retention rates by improving morale (CSRwire, 2002). To explore this, a small, creative company in Johannesburg which engages in charity work was selected as a case study, with the goal being to understand whether their culture of good deeds has a positive impact on staff wellbeing. While the owner of the company actively attempts to make the company an enjoyable place to work at, he appears to have initiated the philanthropic activities in a true spirit of giving, rather than with the motive of engaging staff in order to make more money. Nevertheless, the researcher’s investigative stance is that of an enlightened egoist, and the study focuses on the business case of giving being beneficial to the giver (ultimately the company) in the long term, as well as to the recipient. While the danger of suggesting that philanthropy could be instrumentalised is acknowledged (Morton, 2004), the investigation explores the possibility because such evidence could persuade other companies to become more socially concerned. Through a qualitative approach involving interviews, observation and analysis of video footage, it becomes apparent that there is clearly value for the staff in the charity work they do. Unfortunately the multiple initiatives undertaken to keep staff morale high at the company make it impossible to establish a clear link between the philanthropy and overall wellbeing, but as the study was conducted in the phenomenological paradigm the main concern was with understanding the experience of participants. However, an unexpected finding was that the employees derive great satisfaction from using their professional skills for charity work rather than just donating money to the charity. They feel that their skills uniquely position them to make significant changes to the lives of others, which gives them a sense of pride and achievement that they don’t necessarily experience in their ordinary activities at work. On the basis of this, it is recommended that companies look to involve staff with projects that require their specific expertise when evaluating philanthropic initiatives. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2004
- Full Text:
- Date Issued: 2004-04
- Authors: Ryan, Daniel Reginald
- Date: 2004-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191487 , vital:45103
- Description: In many service industries, the source of a company’s value has shifted from capital to knowledge and ideas, the quality of which is dependent on its employees (Wooldridge, 2006). In fact, human resources can be considered part of factor conditions which can positively impact on a firm’s competitive context. This impact can ultimately translate into improved financial results (Porter and Kramer, 2002). There is therefore a growing interest in ways to attract and retain talent. According to the managers of many big companies, well communicated corporate responsibility practices can improve staff attraction as well as retention rates by improving morale (CSRwire, 2002). To explore this, a small, creative company in Johannesburg which engages in charity work was selected as a case study, with the goal being to understand whether their culture of good deeds has a positive impact on staff wellbeing. While the owner of the company actively attempts to make the company an enjoyable place to work at, he appears to have initiated the philanthropic activities in a true spirit of giving, rather than with the motive of engaging staff in order to make more money. Nevertheless, the researcher’s investigative stance is that of an enlightened egoist, and the study focuses on the business case of giving being beneficial to the giver (ultimately the company) in the long term, as well as to the recipient. While the danger of suggesting that philanthropy could be instrumentalised is acknowledged (Morton, 2004), the investigation explores the possibility because such evidence could persuade other companies to become more socially concerned. Through a qualitative approach involving interviews, observation and analysis of video footage, it becomes apparent that there is clearly value for the staff in the charity work they do. Unfortunately the multiple initiatives undertaken to keep staff morale high at the company make it impossible to establish a clear link between the philanthropy and overall wellbeing, but as the study was conducted in the phenomenological paradigm the main concern was with understanding the experience of participants. However, an unexpected finding was that the employees derive great satisfaction from using their professional skills for charity work rather than just donating money to the charity. They feel that their skills uniquely position them to make significant changes to the lives of others, which gives them a sense of pride and achievement that they don’t necessarily experience in their ordinary activities at work. On the basis of this, it is recommended that companies look to involve staff with projects that require their specific expertise when evaluating philanthropic initiatives. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2004
- Full Text:
- Date Issued: 2004-04
Main thesis title: Onderwysers se belewing van multikulturele onderwys
- Authors: Strydom, Louise
- Date: 1999-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: Afrikaans
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60003 , vital:62732
- Description: The South African Schools’ Act of 1996 terminated segregated education in South Africa. Multi-cultural education has become a reality in the new democratic South Africa. As a result of this major shift in policy, the researcher probed for an answer to the following question: “How does the teacher, especially the teacher already in service, experience this new situation regarding multi-cultural education?” To find an answer to this question, a literature study and empirical research, making use of a representative sample of respondents in the Southern Cape, were undertaken. The researcher has personally experienced the challenges of having to adapt from a mono-cultural teaching environment to a multi-cultural teaching environment at school level, hence a further interest in this research problem. Relevant terminology was highlighted and a brief historical synopsis of the course that multi-cultural education took in Western societies such as the USA, Canada, Australia and Britain was studied. These sources were utilised to draw a comparison with the South African situation. A concise synopsis of the history of multi-cultural education in South Africa was also undertaken to highlight the complexity of the educational situation presently being experienced in South Africa. The empirical research, with a target group representing teachers in the Southern Cape, was undertaken by means of a self-compiled questionnaire to make an analysis of teachers’ attitudes, expectations and perceptions of multi-cultural education as experienced in the classroom. The information obtained from the respondents indicated a generally positive attitude towards multi-cultural education amongst teachers. A great need for in-service training also became evident. xvi The researcher has thus made recommendations regarding in-service training that she thinks is of utmost importance. The practical problems that were highlighted during the research, make a vital contribution towards the successful implementation of multi-cultural education in South Africa. , Thesis (DEd) -- Faculty of Education, 1999
- Full Text:
- Date Issued: 1999-04
- Authors: Strydom, Louise
- Date: 1999-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: Afrikaans
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60003 , vital:62732
- Description: The South African Schools’ Act of 1996 terminated segregated education in South Africa. Multi-cultural education has become a reality in the new democratic South Africa. As a result of this major shift in policy, the researcher probed for an answer to the following question: “How does the teacher, especially the teacher already in service, experience this new situation regarding multi-cultural education?” To find an answer to this question, a literature study and empirical research, making use of a representative sample of respondents in the Southern Cape, were undertaken. The researcher has personally experienced the challenges of having to adapt from a mono-cultural teaching environment to a multi-cultural teaching environment at school level, hence a further interest in this research problem. Relevant terminology was highlighted and a brief historical synopsis of the course that multi-cultural education took in Western societies such as the USA, Canada, Australia and Britain was studied. These sources were utilised to draw a comparison with the South African situation. A concise synopsis of the history of multi-cultural education in South Africa was also undertaken to highlight the complexity of the educational situation presently being experienced in South Africa. The empirical research, with a target group representing teachers in the Southern Cape, was undertaken by means of a self-compiled questionnaire to make an analysis of teachers’ attitudes, expectations and perceptions of multi-cultural education as experienced in the classroom. The information obtained from the respondents indicated a generally positive attitude towards multi-cultural education amongst teachers. A great need for in-service training also became evident. xvi The researcher has thus made recommendations regarding in-service training that she thinks is of utmost importance. The practical problems that were highlighted during the research, make a vital contribution towards the successful implementation of multi-cultural education in South Africa. , Thesis (DEd) -- Faculty of Education, 1999
- Full Text:
- Date Issued: 1999-04
Applications of camphor-derived chiral auxiliaries in the asymmetric synthesis of α-amino acids and other systems
- Authors: Matjila, Joseph Moemise
- Date: 1998-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191501 , vital:45106
- Description: A viable synthetic route to camphor-derived imino lactones as precursors for the asymmetric synthesis of a-amino acids has been established. Several synthetic strategies have been investigated and the required regioisomeric imino lactones were finally obtained via the step-wise condensation of JV-(carbobenzyloxy)glycine with the a-ketols, 3-exo-hydroxycamphor and 2-exo- hydroxy-3-bomanone. Enolates of the camphor imino lactones, generated using potassium tert- butoxide, were reacted with a range of alkyl halides. Dialkylation was observed using the 2-imino lactone, while the regioisomeric 3-imino lactone derivative gave monoalkylated products with diastereoselectivities, shown by NMR spectroscopy, to range from 43% d.e. for the methylated product to > 99% d.e. for larger alkyl groups. The expected preference for endo-alkylation is supported by NMR (chemical shift, coupling constant and NOE) data and was confirmed by acidic hydrolysis of the pentylated 3-imino lactone to afford the known acid. Computer modelling, with the software package HYPERCHEM®, was used to explore the conformational properties of the alkylated products and their enolate precursors. Exploratory work on the enantiomeric beneficiation of racemic amino acids, using alkylated imino lactone derivatives, revealed preferential exo-protonation of the enolate intermediates. Asymmetric Baylis-Hillman reactions between a novel camphor-derived acrylic ester and a range of aldehydes afforded the corresponding 2-(hydroxyalkyl)acrylates in up to 59% d.e., the observed stereoselectivities being sensitive to both steric and electronic factors. Attempts to prepare imino lactone derivatives from ketopinic acid, although unsuccessful, led to the isolation of two novel W-(carbobenzyloxy)glycinates, whose structures were established by 1- and 2-D NMR spectroscopy. Attempts to prepare "BINAP" analogues from dibomyl ether's also proved unsuccessful, but the investigation led to the discovery of a third, novel dibomyl ether. , Thesis (PhD) -- Faculty of Science, Chemistry, 1998
- Full Text:
- Date Issued: 1998-04
- Authors: Matjila, Joseph Moemise
- Date: 1998-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191501 , vital:45106
- Description: A viable synthetic route to camphor-derived imino lactones as precursors for the asymmetric synthesis of a-amino acids has been established. Several synthetic strategies have been investigated and the required regioisomeric imino lactones were finally obtained via the step-wise condensation of JV-(carbobenzyloxy)glycine with the a-ketols, 3-exo-hydroxycamphor and 2-exo- hydroxy-3-bomanone. Enolates of the camphor imino lactones, generated using potassium tert- butoxide, were reacted with a range of alkyl halides. Dialkylation was observed using the 2-imino lactone, while the regioisomeric 3-imino lactone derivative gave monoalkylated products with diastereoselectivities, shown by NMR spectroscopy, to range from 43% d.e. for the methylated product to > 99% d.e. for larger alkyl groups. The expected preference for endo-alkylation is supported by NMR (chemical shift, coupling constant and NOE) data and was confirmed by acidic hydrolysis of the pentylated 3-imino lactone to afford the known acid. Computer modelling, with the software package HYPERCHEM®, was used to explore the conformational properties of the alkylated products and their enolate precursors. Exploratory work on the enantiomeric beneficiation of racemic amino acids, using alkylated imino lactone derivatives, revealed preferential exo-protonation of the enolate intermediates. Asymmetric Baylis-Hillman reactions between a novel camphor-derived acrylic ester and a range of aldehydes afforded the corresponding 2-(hydroxyalkyl)acrylates in up to 59% d.e., the observed stereoselectivities being sensitive to both steric and electronic factors. Attempts to prepare imino lactone derivatives from ketopinic acid, although unsuccessful, led to the isolation of two novel W-(carbobenzyloxy)glycinates, whose structures were established by 1- and 2-D NMR spectroscopy. Attempts to prepare "BINAP" analogues from dibomyl ether's also proved unsuccessful, but the investigation led to the discovery of a third, novel dibomyl ether. , Thesis (PhD) -- Faculty of Science, Chemistry, 1998
- Full Text:
- Date Issued: 1998-04
Morphodynamics of headland bypass dunefields, with special reference to the Cape St Francis headland, Eastern Cape, South Africa
- Authors: Burkinshaw, Jennifer Ruth
- Date: 1998-01
- Subjects: Sand dunes -- South Africa -- Eastern Cape -- Cape St Francis
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52814 , vital:44206
- Description: The temperate Cape south coast, South Africa, is characterised by a series of log-spiral bays bound by low-relief rocky headlands. In South Africa corridors of transverse dunes crossing the headlands are referred to as headland bypass dunefields (HBDs). Sand blown off upwind beaches is transported across the headlands towards the downwind bays, bypassing the littoral route around the headlands. The key to the development of the HBDs is the presence of sandy beaches upwind of the headlands which lie athwart the prevailing winds. The low relief of the headlands and their shoreline configuration, coupled with their exposure to the marine wind regime, are such that the predominant high energy, westerly winds blow directly onshore. The local longshore drift system plays a critical role in replenishing beach sand deflated by the wind. The "type" HBDs occur in the Eastern Cape on the prominent Cape St Francis and Cape Recife headlands where HBDs have been active since at least the Mid to Late Pleistocene. The dunefields have length/width ratios ranging from 3 to over 10. Sand coverage within HBDs is metasaturated, i.e., the transverse dunes are separated by well-defined interdune areas. Average dune height in the larger dunefields in the Eastern Cape is 9-10 m. The HBDs are commonly bound by sidewalls that develop along the interface between the dunefields and vegetation. The stabilised sidewalls provide the most prominent record of former HBD activity and can influence subsequent HBD morphology. The Oyster Bay dunefield on the Cape St Francis headland was chosen for a study of the aeolian morphodynamic processes that operate within these systems. The dunefield currently operates over a distance of about 14 km and a width of 500 - 1200 m; it is at present cut off from its sand source. Shallow lakes develop in the interdune areas after periods of high rainfall. A 2 week airflow study recorded wind speed along the prevailing wind axis of the Oyster Bay dunefield during spring 1990. Wind speed increased significantly downstream until at least the mid-dunefield area during both the prevailing westerly and seasonal easterly winds. The downwind wind speed increase can be partially attributed to topographic acceleration of airflow as it is compressed over the low cape. The extent of the wind speed increase can vary depending on the land/sea temperature contrasts and the temperature structure of the lower atmosphere. Wind speed recorded across the width of the dunefield was slowed down along the margins by vegetation, while a faster core moved down the centre of the dunefield. Rates of dune movement along the prevailing wind axis show a general correspondence between the volume of sand transported eastwards in different areas of the dunefield and the airflow pattern down the length of the dunefield. Sand is transported most efficiently in the centre of the dunefield where westerly flow is at its maximum. Sand transport calculated from dune migration rates is about 50% of potential sand transport calculated from wind data, as flow is metasaturated. Flow off sandy beaches may be naturally below saturation owing to the effect of intertidal moisture and salts binding the sand. In the Eastern Cape metasaturation can be further enhanced by the downwind entrapment of sand by vegetation along the dunefield margins and within wet interdune areas. The 2-dimensional model for bedform development within HBDs focuses on the downwind extension of the dunefields and transmission of sand through the systems. The combination of the high transport capacity of the wind downwind and metasaturated flow maintains the transport of sand across headlands. HBDs operate aerodynamically as erosional or sediment bypassing systems although deflation of the wet interdune areas is limited. Fully functional short HBDs are the most likely to operate with neutral sediment budgets. Long systems are more susceptible to spatial and temporal effects that modify the sandflux through the systems and hence the outflux from the systems. The Oyster Bay dunefield operates with a mildly positive sediment budget because of sediment entrapment downwind. The morphology and morphodynamic behaviour of HBDs is in contrast to that of the tabular transgressive dunefields that form parallel to the shores of the large log-spiral bays of Algoa Bay and St Francis Bay. The existing morphological classification of transgressive dunefields needs to be revised to include headland bypass dunefields. Keywords: headland bypass dunefields, transgressive coastal dunefields, aeolian morphodynamics, Cape St Francis, Cape south coast. , Thesis (PhD) -- Faculty of Science, 1998
- Full Text:
- Date Issued: 1998-01
- Authors: Burkinshaw, Jennifer Ruth
- Date: 1998-01
- Subjects: Sand dunes -- South Africa -- Eastern Cape -- Cape St Francis
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52814 , vital:44206
- Description: The temperate Cape south coast, South Africa, is characterised by a series of log-spiral bays bound by low-relief rocky headlands. In South Africa corridors of transverse dunes crossing the headlands are referred to as headland bypass dunefields (HBDs). Sand blown off upwind beaches is transported across the headlands towards the downwind bays, bypassing the littoral route around the headlands. The key to the development of the HBDs is the presence of sandy beaches upwind of the headlands which lie athwart the prevailing winds. The low relief of the headlands and their shoreline configuration, coupled with their exposure to the marine wind regime, are such that the predominant high energy, westerly winds blow directly onshore. The local longshore drift system plays a critical role in replenishing beach sand deflated by the wind. The "type" HBDs occur in the Eastern Cape on the prominent Cape St Francis and Cape Recife headlands where HBDs have been active since at least the Mid to Late Pleistocene. The dunefields have length/width ratios ranging from 3 to over 10. Sand coverage within HBDs is metasaturated, i.e., the transverse dunes are separated by well-defined interdune areas. Average dune height in the larger dunefields in the Eastern Cape is 9-10 m. The HBDs are commonly bound by sidewalls that develop along the interface between the dunefields and vegetation. The stabilised sidewalls provide the most prominent record of former HBD activity and can influence subsequent HBD morphology. The Oyster Bay dunefield on the Cape St Francis headland was chosen for a study of the aeolian morphodynamic processes that operate within these systems. The dunefield currently operates over a distance of about 14 km and a width of 500 - 1200 m; it is at present cut off from its sand source. Shallow lakes develop in the interdune areas after periods of high rainfall. A 2 week airflow study recorded wind speed along the prevailing wind axis of the Oyster Bay dunefield during spring 1990. Wind speed increased significantly downstream until at least the mid-dunefield area during both the prevailing westerly and seasonal easterly winds. The downwind wind speed increase can be partially attributed to topographic acceleration of airflow as it is compressed over the low cape. The extent of the wind speed increase can vary depending on the land/sea temperature contrasts and the temperature structure of the lower atmosphere. Wind speed recorded across the width of the dunefield was slowed down along the margins by vegetation, while a faster core moved down the centre of the dunefield. Rates of dune movement along the prevailing wind axis show a general correspondence between the volume of sand transported eastwards in different areas of the dunefield and the airflow pattern down the length of the dunefield. Sand is transported most efficiently in the centre of the dunefield where westerly flow is at its maximum. Sand transport calculated from dune migration rates is about 50% of potential sand transport calculated from wind data, as flow is metasaturated. Flow off sandy beaches may be naturally below saturation owing to the effect of intertidal moisture and salts binding the sand. In the Eastern Cape metasaturation can be further enhanced by the downwind entrapment of sand by vegetation along the dunefield margins and within wet interdune areas. The 2-dimensional model for bedform development within HBDs focuses on the downwind extension of the dunefields and transmission of sand through the systems. The combination of the high transport capacity of the wind downwind and metasaturated flow maintains the transport of sand across headlands. HBDs operate aerodynamically as erosional or sediment bypassing systems although deflation of the wet interdune areas is limited. Fully functional short HBDs are the most likely to operate with neutral sediment budgets. Long systems are more susceptible to spatial and temporal effects that modify the sandflux through the systems and hence the outflux from the systems. The Oyster Bay dunefield operates with a mildly positive sediment budget because of sediment entrapment downwind. The morphology and morphodynamic behaviour of HBDs is in contrast to that of the tabular transgressive dunefields that form parallel to the shores of the large log-spiral bays of Algoa Bay and St Francis Bay. The existing morphological classification of transgressive dunefields needs to be revised to include headland bypass dunefields. Keywords: headland bypass dunefields, transgressive coastal dunefields, aeolian morphodynamics, Cape St Francis, Cape south coast. , Thesis (PhD) -- Faculty of Science, 1998
- Full Text:
- Date Issued: 1998-01
Population structure, production, growth, reproduction and the ecology of Atherina breviceps Valenciennes, 1935 (Pisces : Atherinidae) and Gilchristella aestuaria (Gilchrist, 1914) (Pisces : Clupeidae), from two southern Cape coastal lakes
- Authors: Ratte, Theodore Wilhlelm
- Date: 1989-01
- Subjects: Silversides , Clupeidae -- South Africa -- Cape of Good Hope
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/50878 , vital:43029
- Description: Over the period October 1978 to January 1981, a total of 147 853 Atherina breviceps with a total biomass of 55 2B0,7 g and 107 046 Gilchristella aestuaria with a total biomass of 33 708,9 g were collected in the Swartvlei System and 151 531 A. breviceps with a total biomass of 727 795,0 g and 51 258 G. aestuaria with a total biomass of 12 231,5 g were collected in Groenvlei, to determine their population structure, production, growth, reproduction and ecology in both systems. A. breviceps and G. aestuaria were collected from nine and eleven estuaries respectively, including Groenvlei, along the Cape coast to determine the degree of genetic divergence of both these two species in Groenvlei. It was found that the mature 0-year-old A. breviceps and the 2-year-old G. aestuaria dominated the catches in the Swartvlei System, whereas the juvenile 0-year-olds and 1-year-olds of both species respectively, dominated the catches in Groenvlei. The Swartvlei System and Groenvlei produced respectively between 10-12 metric tons of A. breviceps and between 5-3 metric tons of G. aestuaria annually. A. breviceps and G. aestuana in the Swartvlei System and Groenvlei attain observed ages of between 3 years and 7-8 years respectively. The main spawning period for both species is between spring-autumn in Groenvlei and for A. breviceps in the Swartvlei System. G. aestuaria has a continuous winter-summer spawning in the Swartvlei System. A. breviceps and G. aestuaria in Groenvlei have diverged to such an extent from these two species' populations in other systems, that A. breviceps and G. aestuaria in Groenvlei should receive a priority conservation status. , Thesis (PhD) -- Faculty of Science, 1989
- Full Text:
- Date Issued: 1989-01
- Authors: Ratte, Theodore Wilhlelm
- Date: 1989-01
- Subjects: Silversides , Clupeidae -- South Africa -- Cape of Good Hope
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/50878 , vital:43029
- Description: Over the period October 1978 to January 1981, a total of 147 853 Atherina breviceps with a total biomass of 55 2B0,7 g and 107 046 Gilchristella aestuaria with a total biomass of 33 708,9 g were collected in the Swartvlei System and 151 531 A. breviceps with a total biomass of 727 795,0 g and 51 258 G. aestuaria with a total biomass of 12 231,5 g were collected in Groenvlei, to determine their population structure, production, growth, reproduction and ecology in both systems. A. breviceps and G. aestuaria were collected from nine and eleven estuaries respectively, including Groenvlei, along the Cape coast to determine the degree of genetic divergence of both these two species in Groenvlei. It was found that the mature 0-year-old A. breviceps and the 2-year-old G. aestuaria dominated the catches in the Swartvlei System, whereas the juvenile 0-year-olds and 1-year-olds of both species respectively, dominated the catches in Groenvlei. The Swartvlei System and Groenvlei produced respectively between 10-12 metric tons of A. breviceps and between 5-3 metric tons of G. aestuaria annually. A. breviceps and G. aestuana in the Swartvlei System and Groenvlei attain observed ages of between 3 years and 7-8 years respectively. The main spawning period for both species is between spring-autumn in Groenvlei and for A. breviceps in the Swartvlei System. G. aestuaria has a continuous winter-summer spawning in the Swartvlei System. A. breviceps and G. aestuaria in Groenvlei have diverged to such an extent from these two species' populations in other systems, that A. breviceps and G. aestuaria in Groenvlei should receive a priority conservation status. , Thesis (PhD) -- Faculty of Science, 1989
- Full Text:
- Date Issued: 1989-01
The biology of the sand shark Rhinobatos Annulatus, in Algoa Bay with notes on other elasmobranchs
- Authors: Rossouw, Gideon Johannes
- Date: 1983
- Subjects: Sand sharks , Guitarfishes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52802 , vital:44061
- Description: The biology of the lesser sand shark, Rhinobatos annulatus, was studied off sandy beaches in Algoa Bay over a period of two years. Tagging studies, due to low numbers tagged, did not reveal major movements. However, comparison of numbers of sand sharks caught off the beach and deep water during summer and winter months suggested that migration occurred during these seasons with the animals being inshore in summer. Annual rings on the vertebral centra were used to determine age. Both sexes can reach a maximum age of seven years. Conventional growth curves could not be fitted and empirical curves were used to illustrate growth. The reproductive cycle was investigated and indicated that both sexes matured after three years of age. The breeding season was during late summer when the shallow water was utilized as a nursery area. The sand shark is an aplacental viviparous species with a gestation period of 10 months. Breeding occurred every year and fecundity increased with total body length to a maximum litter size of 10 young. The most important prey items taken inshore were the mysid Gastrosaccus psammodytes, the prawn Macropetasma africanum, the crab Ovalipes punctatus and the sand mussels Donax spp. Differential predation by different length classes of sand shark resulted from a dynamic zonation of these different size classes in the surf zone. Smallest individuals fed closest inshore. Seasonal variation recorded in the hepatosomatic index was primarily due to the accumulation of hepatic lipids. This variation showed significant correlations with the breeding cycle in adult sand sharks. The contribution of liver lipids to the formation of egg yolk was estimated and found to be secondary to lipid reserves for maintenance. Liver colour varied depended on the amount of liver lipids. Ancillary observations were made of other elasmobranchs in the surf zone. , Thesis (DPhil) -- Faculty of Science, 1983
- Full Text:
- Date Issued: 1983
- Authors: Rossouw, Gideon Johannes
- Date: 1983
- Subjects: Sand sharks , Guitarfishes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52802 , vital:44061
- Description: The biology of the lesser sand shark, Rhinobatos annulatus, was studied off sandy beaches in Algoa Bay over a period of two years. Tagging studies, due to low numbers tagged, did not reveal major movements. However, comparison of numbers of sand sharks caught off the beach and deep water during summer and winter months suggested that migration occurred during these seasons with the animals being inshore in summer. Annual rings on the vertebral centra were used to determine age. Both sexes can reach a maximum age of seven years. Conventional growth curves could not be fitted and empirical curves were used to illustrate growth. The reproductive cycle was investigated and indicated that both sexes matured after three years of age. The breeding season was during late summer when the shallow water was utilized as a nursery area. The sand shark is an aplacental viviparous species with a gestation period of 10 months. Breeding occurred every year and fecundity increased with total body length to a maximum litter size of 10 young. The most important prey items taken inshore were the mysid Gastrosaccus psammodytes, the prawn Macropetasma africanum, the crab Ovalipes punctatus and the sand mussels Donax spp. Differential predation by different length classes of sand shark resulted from a dynamic zonation of these different size classes in the surf zone. Smallest individuals fed closest inshore. Seasonal variation recorded in the hepatosomatic index was primarily due to the accumulation of hepatic lipids. This variation showed significant correlations with the breeding cycle in adult sand sharks. The contribution of liver lipids to the formation of egg yolk was estimated and found to be secondary to lipid reserves for maintenance. Liver colour varied depended on the amount of liver lipids. Ancillary observations were made of other elasmobranchs in the surf zone. , Thesis (DPhil) -- Faculty of Science, 1983
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- Date Issued: 1983