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An investigation into the visual literacy skills of Black primary-school children from an informal settlement in Cape Town, with particular reference to visual imagery in educational textbooks
- Authors: Griffiths, Corona Gracelyn
- Date: 1997
- Subjects: Textbooks Illustrations , Visual literacy , Literacy -- South Africa , Visual literacy -- South Africa , Visual communication , Blacks -- Education (Primary) -- South Africa , School children -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2403 , http://hdl.handle.net/10962/d1002199 , Textbooks Illustrations , Visual literacy , Literacy -- South Africa , Visual literacy -- South Africa , Visual communication , Blacks -- Education (Primary) -- South Africa , School children -- South Africa
- Description: This thesis provides evidence that learning difficulties some. black primary-schoolchildren may experience with certain textbooks, can be attributed, in part, to the visual text (imagery). These difficulties were established by eliciting responses from educationally dlscfdvantaged urban black primary learners to selected examples of visual texts using the Research Interview method. To further establish if these difficulties were attributable either to poorly executed/unrecognizable visual text, or to low levels of learned educational visual literacy skills - white primary-school children were also interviewed - as it was anticipated that they would be familiar with Western pictorial material due to their consistent exposure to books from an early age. The difficulties experienced by the black interviewees were attributed mainly to their level of learned pictorial perceptual skills and to a lesser extent to poorly/inadequately illustrated visual texts. It was found from interviews with the developers of visual texts - publishing personnel and illustrators - that the former were not entirely certain e.xactly which aspects of visual text were difficult for black primary learners to comprehend, while the latter were generaUy very uncertain. The procedure for visual text development by the developers (including textbook authors), was found to be problematic due to the lack of synthesis and consultative decision making in the process- between these persons. The limited time allocated to illustrators for producing visual text, as well as their professional isolation, were found to be factors which can give rise to ineffective and inadequate visual texts. Most publishers and authors, if they trial (field-test) materials, generally do not trial the visual text. The visual text is usually decided upon ultimately by the poblishers and produced after trialling and/or consultants have examined the written text. Consequently incongruent meanings and inconsistencies can result between written and visual text, which can affect the learning effectiveness of the composite text. Trialling (field-testing) of visual and written text together, was recommended to identify and address any difficulties experienced by learners prior to final publication of the textbook. Recommendations were provided for textbook selection committees, authors, teachers, publishers and illustrators.
- Full Text:
- Date Issued: 1997
- Authors: Griffiths, Corona Gracelyn
- Date: 1997
- Subjects: Textbooks Illustrations , Visual literacy , Literacy -- South Africa , Visual literacy -- South Africa , Visual communication , Blacks -- Education (Primary) -- South Africa , School children -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2403 , http://hdl.handle.net/10962/d1002199 , Textbooks Illustrations , Visual literacy , Literacy -- South Africa , Visual literacy -- South Africa , Visual communication , Blacks -- Education (Primary) -- South Africa , School children -- South Africa
- Description: This thesis provides evidence that learning difficulties some. black primary-schoolchildren may experience with certain textbooks, can be attributed, in part, to the visual text (imagery). These difficulties were established by eliciting responses from educationally dlscfdvantaged urban black primary learners to selected examples of visual texts using the Research Interview method. To further establish if these difficulties were attributable either to poorly executed/unrecognizable visual text, or to low levels of learned educational visual literacy skills - white primary-school children were also interviewed - as it was anticipated that they would be familiar with Western pictorial material due to their consistent exposure to books from an early age. The difficulties experienced by the black interviewees were attributed mainly to their level of learned pictorial perceptual skills and to a lesser extent to poorly/inadequately illustrated visual texts. It was found from interviews with the developers of visual texts - publishing personnel and illustrators - that the former were not entirely certain e.xactly which aspects of visual text were difficult for black primary learners to comprehend, while the latter were generaUy very uncertain. The procedure for visual text development by the developers (including textbook authors), was found to be problematic due to the lack of synthesis and consultative decision making in the process- between these persons. The limited time allocated to illustrators for producing visual text, as well as their professional isolation, were found to be factors which can give rise to ineffective and inadequate visual texts. Most publishers and authors, if they trial (field-test) materials, generally do not trial the visual text. The visual text is usually decided upon ultimately by the poblishers and produced after trialling and/or consultants have examined the written text. Consequently incongruent meanings and inconsistencies can result between written and visual text, which can affect the learning effectiveness of the composite text. Trialling (field-testing) of visual and written text together, was recommended to identify and address any difficulties experienced by learners prior to final publication of the textbook. Recommendations were provided for textbook selection committees, authors, teachers, publishers and illustrators.
- Full Text:
- Date Issued: 1997
Negotiating a comprehensive long-term relationship between South Africa and the European Union: from free trade to trade and development
- Authors: Cross, Peter John
- Date: 1997
- Subjects: Economic development -- South Africa -- 1994- , European Economic Community , European Economic Community countries -- Foreign economic relations -- South Africa , South Africa -- Foreign relations -- European Economic Community countries
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2768 , http://hdl.handle.net/10962/d1002978 , Economic development -- South Africa -- 1994- , European Economic Community , European Economic Community countries -- Foreign economic relations -- South Africa , South Africa -- Foreign relations -- European Economic Community countries
- Description: On 10 May 1994 the European Union offeredSouth Africa a package of measures to ... send a strong political signal to the incoming govemment and to the South African population, thus proving its firm determination to support the transition towards democracy and its willingness to contribute to the reconstruction and economic development of South Africa after the elections. This package consisted of two parts: 1. A series of short term implementations to take place with immediate effect to help South Africa's development and transition, and 2. An offer to negotiate a comprehensive long-term relationship with South Africa should the new government so request. South Africa accepted the European Union's offer to negotiate a long-term relationship, and in response requested membership of the structure governing the Union's relations with the rest of the countries in Sub-Saharan Africa and some countries in the Caribbean and Pacific, namely the Lomé Convention. Due to various incompatibilities South Africa was not allowed to join this organisation. In its place the European Union offered to negotiate an agreement with South Africa that would lead to a Free Trade Area. This agreement was in keeping with the rules as laid down by the World Trade Organisation. It envisaged the lowering of tariffs and trade barriers between the Union and South Africa over a period not exceeding 12 years, allowing for asymmetry in terms of time constraints in implementation only. South Africa saw this type of agreement as inconsistent with the desire expressed by the European Union to support the countries development and the integration of the Southern African region. In its place South Africa proposed a new concept in trade agreement, this concept, known as the Trade and Development Agreement, embodied both trade liberalisation and support for development. This agreement would introduce a new paradigm of thought to govern trade between developed countries and developing countries within the World Trade Organisation's rules. This paper explores the events that unfolded in these negotiations. It attempts to discover whether, in the current global environment, it is possible, or beneficial, for the developed world to act in an altruistic manner towards another state in order to assist its development.
- Full Text:
- Date Issued: 1997
- Authors: Cross, Peter John
- Date: 1997
- Subjects: Economic development -- South Africa -- 1994- , European Economic Community , European Economic Community countries -- Foreign economic relations -- South Africa , South Africa -- Foreign relations -- European Economic Community countries
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2768 , http://hdl.handle.net/10962/d1002978 , Economic development -- South Africa -- 1994- , European Economic Community , European Economic Community countries -- Foreign economic relations -- South Africa , South Africa -- Foreign relations -- European Economic Community countries
- Description: On 10 May 1994 the European Union offeredSouth Africa a package of measures to ... send a strong political signal to the incoming govemment and to the South African population, thus proving its firm determination to support the transition towards democracy and its willingness to contribute to the reconstruction and economic development of South Africa after the elections. This package consisted of two parts: 1. A series of short term implementations to take place with immediate effect to help South Africa's development and transition, and 2. An offer to negotiate a comprehensive long-term relationship with South Africa should the new government so request. South Africa accepted the European Union's offer to negotiate a long-term relationship, and in response requested membership of the structure governing the Union's relations with the rest of the countries in Sub-Saharan Africa and some countries in the Caribbean and Pacific, namely the Lomé Convention. Due to various incompatibilities South Africa was not allowed to join this organisation. In its place the European Union offered to negotiate an agreement with South Africa that would lead to a Free Trade Area. This agreement was in keeping with the rules as laid down by the World Trade Organisation. It envisaged the lowering of tariffs and trade barriers between the Union and South Africa over a period not exceeding 12 years, allowing for asymmetry in terms of time constraints in implementation only. South Africa saw this type of agreement as inconsistent with the desire expressed by the European Union to support the countries development and the integration of the Southern African region. In its place South Africa proposed a new concept in trade agreement, this concept, known as the Trade and Development Agreement, embodied both trade liberalisation and support for development. This agreement would introduce a new paradigm of thought to govern trade between developed countries and developing countries within the World Trade Organisation's rules. This paper explores the events that unfolded in these negotiations. It attempts to discover whether, in the current global environment, it is possible, or beneficial, for the developed world to act in an altruistic manner towards another state in order to assist its development.
- Full Text:
- Date Issued: 1997
Title not specified
- Three Lunyankole men, Tracey, Andrew T N
- Authors: Three Lunyankole men , Tracey, Andrew T N
- Date: 1997
- Subjects: Nyankole (African people) -- Uganda , Music -- Religious aspects , Harp , Drum music , Sub-Saharan African music , Africa Uganda Ankole f-ug
- Language: English
- Type: sound recordings , field recordings , Sound recording material
- Identifier: http://hdl.handle.net/10962/93405 , vital:30877 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC027-03
- Description: Church song accompanied by two harps and a drum.
- Full Text: false
- Date Issued: 1997
- Authors: Three Lunyankole men , Tracey, Andrew T N
- Date: 1997
- Subjects: Nyankole (African people) -- Uganda , Music -- Religious aspects , Harp , Drum music , Sub-Saharan African music , Africa Uganda Ankole f-ug
- Language: English
- Type: sound recordings , field recordings , Sound recording material
- Identifier: http://hdl.handle.net/10962/93405 , vital:30877 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC027-03
- Description: Church song accompanied by two harps and a drum.
- Full Text: false
- Date Issued: 1997
Environmental perceptions and knowledge among political leaders in the Eastern Cape Province and some implications for environmental policy
- Authors: Mbengashe, Pauline Maria
- Date: 1997
- Subjects: Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1517 , http://hdl.handle.net/10962/d1003399
- Description: The environmental and development challenges facing South Africa are closely linked with the political and economic inequalities of the past. The achievement of sustainable. development will require social and political change. Protection and conservation of the environment, improving environmental knowledge and understanding, the participation of all citizens, effective environmental management, inclusive and implementable policies and legislation, are all necessary components of sustainable development. These requirements are in line with the Rio Declaration on Environment and Development and Agenda 21, a programme of action coming out of the United Nations Conference on Environment and Development (UNCED 1992) This study explores the environmental perceptions and knowledge of some representative Eastern Cape political leaders. The aim of the study was to share views on environmental issues, concerns and strategies that might lead to improved environmental understanding, informed policy change and effective environmental management. Different environmental ideologies were also explored because of the political and ideological nature of the concepts 'environment' and 'education'. Data was collected from semi-structured interviews undertaken with ten political leaders in the Eastern Cape Province Legislature. The study revealed a general awareness and understanding of environmental issues with unsupported indepth knowledge and detailed information. The political, development, social and economic dimensions of the environment were emphasised more than the ecological and physical aspects. The need for environmental information, policies and legislation was recognised. Both formal and non-formal environmental education were emphasised. The need to redefine environmental education and make it more relevant, problem solving and action oriented was also emphasised. The challenge is to improve environmental understanding and making environmental information available to political leaders, government officials and citizens in general.
- Full Text:
- Date Issued: 1997
- Authors: Mbengashe, Pauline Maria
- Date: 1997
- Subjects: Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1517 , http://hdl.handle.net/10962/d1003399
- Description: The environmental and development challenges facing South Africa are closely linked with the political and economic inequalities of the past. The achievement of sustainable. development will require social and political change. Protection and conservation of the environment, improving environmental knowledge and understanding, the participation of all citizens, effective environmental management, inclusive and implementable policies and legislation, are all necessary components of sustainable development. These requirements are in line with the Rio Declaration on Environment and Development and Agenda 21, a programme of action coming out of the United Nations Conference on Environment and Development (UNCED 1992) This study explores the environmental perceptions and knowledge of some representative Eastern Cape political leaders. The aim of the study was to share views on environmental issues, concerns and strategies that might lead to improved environmental understanding, informed policy change and effective environmental management. Different environmental ideologies were also explored because of the political and ideological nature of the concepts 'environment' and 'education'. Data was collected from semi-structured interviews undertaken with ten political leaders in the Eastern Cape Province Legislature. The study revealed a general awareness and understanding of environmental issues with unsupported indepth knowledge and detailed information. The political, development, social and economic dimensions of the environment were emphasised more than the ecological and physical aspects. The need for environmental information, policies and legislation was recognised. Both formal and non-formal environmental education were emphasised. The need to redefine environmental education and make it more relevant, problem solving and action oriented was also emphasised. The challenge is to improve environmental understanding and making environmental information available to political leaders, government officials and citizens in general.
- Full Text:
- Date Issued: 1997
Responding to literature: empowering girls to speak with their own voices in a multicultural context
- Authors: Foster, Lesley
- Date: 1997
- Subjects: Reader-response criticism--South Africa Multicultural education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1742 , http://hdl.handle.net/10962/d1003626
- Description: The purpose of this study was to investigate whether the space provided by a readerresponse transaction between girls and the text, Roll of Thunder, Hear My Cry (Taylor 1977) .. empowered pupils to tell their own stories. It also sought to identify ways in which the problems and possibilities perceived by these pupils might guide curriculum decisions in a transforming education system. In addition to engaging in reader-response activities around the text, drama and videos providing social context were integral to the programme. Related work in the subject areas of history and lifeskills was also undertaken. Data was drawn from pupils' reading journals, responses to specific passages, transcripts of small group discussions, and interviews. The study is ethnographic in nature and all the data qualitative. Theoretical insights were drawn from the felds of cultural studies, postmodern criticism, and postructural modes of cultural and social analysis inasfar as they illuminate and inform the relationship between language, knowledge and power. The research was conducted in an historically white, girls' school which adopted a nonracial admissions policy in January 1991. Despite the fact that existing traditions and values of the the school to a very large extent influence what is taught, the data suggests that pupils were becoming agents in their own learning and were taking up multiple identities both within and without the world of the school.
- Full Text:
- Date Issued: 1997
Responding to literature: empowering girls to speak with their own voices in a multicultural context
- Authors: Foster, Lesley
- Date: 1997
- Subjects: Reader-response criticism--South Africa Multicultural education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1742 , http://hdl.handle.net/10962/d1003626
- Description: The purpose of this study was to investigate whether the space provided by a readerresponse transaction between girls and the text, Roll of Thunder, Hear My Cry (Taylor 1977) .. empowered pupils to tell their own stories. It also sought to identify ways in which the problems and possibilities perceived by these pupils might guide curriculum decisions in a transforming education system. In addition to engaging in reader-response activities around the text, drama and videos providing social context were integral to the programme. Related work in the subject areas of history and lifeskills was also undertaken. Data was drawn from pupils' reading journals, responses to specific passages, transcripts of small group discussions, and interviews. The study is ethnographic in nature and all the data qualitative. Theoretical insights were drawn from the felds of cultural studies, postmodern criticism, and postructural modes of cultural and social analysis inasfar as they illuminate and inform the relationship between language, knowledge and power. The research was conducted in an historically white, girls' school which adopted a nonracial admissions policy in January 1991. Despite the fact that existing traditions and values of the the school to a very large extent influence what is taught, the data suggests that pupils were becoming agents in their own learning and were taking up multiple identities both within and without the world of the school.
- Full Text:
- Date Issued: 1997
A collated digital, geological map database for the central Namaqua Province using geographical information system technology
- Authors: Holland, Henry
- Date: 1997
- Subjects: Geographic information systems , Namaqua Province (South Africa) -- Maps Databases , Geology Maps , Cartography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4936 , http://hdl.handle.net/10962/d1005548 , Geographic information systems , Namaqua Province (South Africa) -- Maps Databases , Geology Maps , Cartography
- Description: The genlogy of the Namaqua Province is notoriously difficult to map and interpret due to polymetamorphic and multiple deformation events and limlted outcrop. Current maps of the Province reflect diverse interpretations of stratigraphy as a consequence of these difficulties. A Geographic Information System is essentially a digital database and a set of functions and procedures to capture, analyse and manipulate spatially related data. A GIS is therefore ideally suited to the study and analysis of maps. A digital map database was established, using modem GIS technology, to facilitate the collation of existing maps of an area in the Central Namaqua Province (CNP). This database is based on a lithological classification system similar to that used by Harris (1992), rather than on an interpretive stratigraphic model. In order to establish the database, existing geological maps were scanned into a GIS, and lines of outcrop and lithological contacts were digitised using a manual line following process, which is one of the functions native to a GIS. Attribute data were then attached to the resultant polygons. The attribute database consists of lithological, textural and mineralogical data, as well as stratigraphical classification data according to the South African Committee for Stratigraphy (SACS), correlative names assigned to units by the Precambrian Research Unit, the Geological Survey of South Africa, the Bushmanland Research group and the University of the Orange Free State. Other attribute data included in the database, are tectonic and absolute age information, and the terrane classification for the area. This database reflects the main objective of the project and also serves as a basis for further expansion of a geological GIS for the CNP. Cartographic and database capabilities of the GIS were employed to produce a collated lithological map of the CNP. A TNTmipsTM Spatial Manipulation Language routine was written to produce a database containing two fields linked to each polygon, one for lithology and one for a correlation probability factor. Correlation factors are calculated in this routine from three variables, namely the prominence a worker attached to a specific lithology within a unit or outcrop, the agreement amongst the various workers on the actual lithology present within an outcrop, and the correspondence between the source of the spatial element (mapped outcrop) and the source of the attribute data attached to it. Outcrops were displayed on the map according to the lithology with the highest correlation factor, providing a unique view of the spatial relationships and distribution patterns of lithological units in the CNP. A second map was produced indicating the correlation factors for lithologies within the CNP. Thematic maps are produced in a GIS by selecting spatial elements according to a set of criteria, usually based on the attribute database, and then displaying the elements as maps. Maps created by this process are known as customised maps, since users of the GIS can customise the selection and display of elements according to their needs. For instance, all outcrops of rock units containing particular lithologies of a given age occurring in a specific terrane can be displayed - either on screen or printed out as a map. The database also makes it possible to plot maps according to different stratigraphic classification systems. Areas where various workers disagree on the stratigraphic classification of units can be isolated, and displayed as separate maps in order to aid in the collation process. The database can assist SACS in identifying areas in the CNP where stratigraphic classification is still lacking or agreements on stratigraphic nomenclature have not yet been attained. More than one database can be attached to the spatial elements in a GIS, and the Namaqua-GIS can therefore be expanded to include geochemical, geophysical, economic, structural and geographical data. Other data on the area, such as more detailed maps, photographs and satellite images can be attached to the lithological map database in the correct spatial relationship. Another advantage of a GIS is the facility to continually update the database(s) as more information becomes available and/or as interpretation of the area is refined.
- Full Text:
- Date Issued: 1997
- Authors: Holland, Henry
- Date: 1997
- Subjects: Geographic information systems , Namaqua Province (South Africa) -- Maps Databases , Geology Maps , Cartography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4936 , http://hdl.handle.net/10962/d1005548 , Geographic information systems , Namaqua Province (South Africa) -- Maps Databases , Geology Maps , Cartography
- Description: The genlogy of the Namaqua Province is notoriously difficult to map and interpret due to polymetamorphic and multiple deformation events and limlted outcrop. Current maps of the Province reflect diverse interpretations of stratigraphy as a consequence of these difficulties. A Geographic Information System is essentially a digital database and a set of functions and procedures to capture, analyse and manipulate spatially related data. A GIS is therefore ideally suited to the study and analysis of maps. A digital map database was established, using modem GIS technology, to facilitate the collation of existing maps of an area in the Central Namaqua Province (CNP). This database is based on a lithological classification system similar to that used by Harris (1992), rather than on an interpretive stratigraphic model. In order to establish the database, existing geological maps were scanned into a GIS, and lines of outcrop and lithological contacts were digitised using a manual line following process, which is one of the functions native to a GIS. Attribute data were then attached to the resultant polygons. The attribute database consists of lithological, textural and mineralogical data, as well as stratigraphical classification data according to the South African Committee for Stratigraphy (SACS), correlative names assigned to units by the Precambrian Research Unit, the Geological Survey of South Africa, the Bushmanland Research group and the University of the Orange Free State. Other attribute data included in the database, are tectonic and absolute age information, and the terrane classification for the area. This database reflects the main objective of the project and also serves as a basis for further expansion of a geological GIS for the CNP. Cartographic and database capabilities of the GIS were employed to produce a collated lithological map of the CNP. A TNTmipsTM Spatial Manipulation Language routine was written to produce a database containing two fields linked to each polygon, one for lithology and one for a correlation probability factor. Correlation factors are calculated in this routine from three variables, namely the prominence a worker attached to a specific lithology within a unit or outcrop, the agreement amongst the various workers on the actual lithology present within an outcrop, and the correspondence between the source of the spatial element (mapped outcrop) and the source of the attribute data attached to it. Outcrops were displayed on the map according to the lithology with the highest correlation factor, providing a unique view of the spatial relationships and distribution patterns of lithological units in the CNP. A second map was produced indicating the correlation factors for lithologies within the CNP. Thematic maps are produced in a GIS by selecting spatial elements according to a set of criteria, usually based on the attribute database, and then displaying the elements as maps. Maps created by this process are known as customised maps, since users of the GIS can customise the selection and display of elements according to their needs. For instance, all outcrops of rock units containing particular lithologies of a given age occurring in a specific terrane can be displayed - either on screen or printed out as a map. The database also makes it possible to plot maps according to different stratigraphic classification systems. Areas where various workers disagree on the stratigraphic classification of units can be isolated, and displayed as separate maps in order to aid in the collation process. The database can assist SACS in identifying areas in the CNP where stratigraphic classification is still lacking or agreements on stratigraphic nomenclature have not yet been attained. More than one database can be attached to the spatial elements in a GIS, and the Namaqua-GIS can therefore be expanded to include geochemical, geophysical, economic, structural and geographical data. Other data on the area, such as more detailed maps, photographs and satellite images can be attached to the lithological map database in the correct spatial relationship. Another advantage of a GIS is the facility to continually update the database(s) as more information becomes available and/or as interpretation of the area is refined.
- Full Text:
- Date Issued: 1997
Epithermal precious metal deposits physicochemical constraints, classification characteristics and exploration guidelines
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997
Effects of sustained elevated CO₂ concentration on two cultivars of barley (Hordeum vulgare L.)
- Authors: Siphugu, Mashudu Victor
- Date: 1997
- Subjects: Barley Barley -- Growth Photosynthesis -- Research Plants -- Effect of carbon dioxide on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4226 , http://hdl.handle.net/10962/d1003795
- Description: The enormous burning of fossil fuel and deforestation have caused an increase in the atmospheric CO₂ concentration ([CO₂]) during the last century. This will invariably have profound direct and indirect effects on plant carbon metabolism. The majority of research on the effects of CO₂ enrichment on plants are short-term and are done on other crops, but very little have been done on barley. This project aimed to determine the effects of long-term CO₂ enrichment on photosynthesis, growth and grain yield on barley. Hordeum vulgare L. cvs Stirling and Schooner plants were grown from seeds in controlled environment chambers at ambient (350) and elevated (600) μmol molˉ¹ [CO₂]. Measurements of net assimilation rate (NAR), photosynthetic pigments content and growth parameters were started 7 days after germination (DAG) and continued until senescence. The anatomy of matured fully developed leaves was also monitored. Elevated [CO₂l resulted in an increase in NAR in the two cultivars from days 7 until 14, after which the stimulation of NAR of CO₂-enriched plants started to decrease. At the onset of senescence, NAR was almost equal in plants grown under both ambient and elevated [CO₂]. The response of assimilation as a function of internal [CO₂l (C₁) at the end of the experimental period showed a significant decrease in both the initial slope of the A/C₁ curves and the CO₂-saturated photosynthetic rates in the two cultivars. Stirling showed no significant changes in the content of chlorophyll α,chlorophyll б or in total carotenoids. However, Schooner showed a stimulation in chlorophyll α content at day 7, but decreased at day 28. Chlorophyll б and total carotenoids content were not affected by CO₂ enrichment. While total above-ground biomass was not affected by elevated [CO₂] in the two cultivars, total plant height decreased significantly after 14 days in Stirling whereas no significant change occurred in Schooner throughout the experimental period. Leaf area was not significantly affected by CO₂ enrichment in the two cultivars although the leaves in CO₂ enriched plants were slightly shorter. Anatomical studies reveal that leaf thickness was significantly increased by CO₂ enrichment in Stirling, but the increase was not significant in Schooner. Both cultivars did not show any significant effect on chloroplast morphology and ultrastructure as a consequence of elevated CO₂ exposure. No signs of starch accumulation were evident in variety Schooner, but Stirling showed some form of starch accumulation, under increased atmospheric [CO₂]. Elevated CO₂ resulted in a significant reduction by more than 50 % in the number of grain yield per plant in both Stirling and Schooner. Results from this study therefore indicate that CO₂ enrichment will not be beneficial in terms of growth and yield in this important crop.
- Full Text:
- Date Issued: 1997
- Authors: Siphugu, Mashudu Victor
- Date: 1997
- Subjects: Barley Barley -- Growth Photosynthesis -- Research Plants -- Effect of carbon dioxide on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4226 , http://hdl.handle.net/10962/d1003795
- Description: The enormous burning of fossil fuel and deforestation have caused an increase in the atmospheric CO₂ concentration ([CO₂]) during the last century. This will invariably have profound direct and indirect effects on plant carbon metabolism. The majority of research on the effects of CO₂ enrichment on plants are short-term and are done on other crops, but very little have been done on barley. This project aimed to determine the effects of long-term CO₂ enrichment on photosynthesis, growth and grain yield on barley. Hordeum vulgare L. cvs Stirling and Schooner plants were grown from seeds in controlled environment chambers at ambient (350) and elevated (600) μmol molˉ¹ [CO₂]. Measurements of net assimilation rate (NAR), photosynthetic pigments content and growth parameters were started 7 days after germination (DAG) and continued until senescence. The anatomy of matured fully developed leaves was also monitored. Elevated [CO₂l resulted in an increase in NAR in the two cultivars from days 7 until 14, after which the stimulation of NAR of CO₂-enriched plants started to decrease. At the onset of senescence, NAR was almost equal in plants grown under both ambient and elevated [CO₂]. The response of assimilation as a function of internal [CO₂l (C₁) at the end of the experimental period showed a significant decrease in both the initial slope of the A/C₁ curves and the CO₂-saturated photosynthetic rates in the two cultivars. Stirling showed no significant changes in the content of chlorophyll α,chlorophyll б or in total carotenoids. However, Schooner showed a stimulation in chlorophyll α content at day 7, but decreased at day 28. Chlorophyll б and total carotenoids content were not affected by CO₂ enrichment. While total above-ground biomass was not affected by elevated [CO₂] in the two cultivars, total plant height decreased significantly after 14 days in Stirling whereas no significant change occurred in Schooner throughout the experimental period. Leaf area was not significantly affected by CO₂ enrichment in the two cultivars although the leaves in CO₂ enriched plants were slightly shorter. Anatomical studies reveal that leaf thickness was significantly increased by CO₂ enrichment in Stirling, but the increase was not significant in Schooner. Both cultivars did not show any significant effect on chloroplast morphology and ultrastructure as a consequence of elevated CO₂ exposure. No signs of starch accumulation were evident in variety Schooner, but Stirling showed some form of starch accumulation, under increased atmospheric [CO₂]. Elevated CO₂ resulted in a significant reduction by more than 50 % in the number of grain yield per plant in both Stirling and Schooner. Results from this study therefore indicate that CO₂ enrichment will not be beneficial in terms of growth and yield in this important crop.
- Full Text:
- Date Issued: 1997
Environmental education : a strategy for primary teacher education
- Authors: Wagiet, Razeena
- Date: 1997
- Subjects: Environmental education -- Study and teaching (Elementary) Environmental education -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1512 , http://hdl.handle.net/10962/d1003394
- Description: This research focuses on environmental education in initial teacher education, and is grounded in three interlinked and widely recognised assumptions. First, that education for sustainable living can assist in resolving some environmental problems that are contributing to the environmental crises of sustainability currently facing South Africa and the rest of the world. Second, that education for sustainable living can assist in the establishment of a new environmental ethic that will foster a sustainable way of living. Third, that teacher education is a vital process for the attainment of both. These assumptions inform the aim of this research, which is to explore the potential for the implementation of education for sustainable living, and to identify a strategy for this, for initial teacher education, for senior primary school student teachers in the Western Cape. The strategy is derived following the grounded theory approach, developed through the case study method. In the process of identifying the strategy, this study establishes that there are challenges at macro, meso and micro levels that are obstructing the changes necessary for education for sustainable living. Change theory provides the basis for explaining these shortcomings, by helping to identify the barriers that might obstruct the realisation of the changes that are necessary for education for sustainable living. These challenges need to be perceived in the light of overcoming three sets of barriers in the way of the potential implementation of education for sustainable living in teacher education. First are those that can be ascribed to the formal education system that, while clinging to Western, Eurocentric values on the one hand, bave also failed to secure a policy for environmental education on the other. Second are the barriers ascribed to the teacher educators themselves, with the whole notion of their powerlessness at its core. Finally, there are the logistical barriers, which encompass, for example, time and financial constraints. With these barriers as a backdrop, to facilitate the incorporation of environmental education into initial teacher education, the study identifies a need for the development of a strategy to secure that education for sustainable living assumes its rightful place in the curriculum for initial teacher education. This framework emerges from the theory grounded in the interviewees' responses during the research, and from the theory grounded in the literature. Central to this framework is for education for sustainable living to contribute to the realisation of real change, change that would further the transformation of our conflict-riddled and inequitable society towards a more democratic and just one. This thesis demonstrates that the realisation of the changes necessary for education for sustainable living demand a reconstruction of current teacher education in order to secure and to sustain an appropriate and sound education ethic to form the basis of a trans formative teacher education curriculum for sustainable living within initial teacher education. Except formal policy, but central to overcoming these barriers, is the need for professional development programmes for teacher educators. A strategy in this regard, is outlined.
- Full Text:
- Date Issued: 1997
- Authors: Wagiet, Razeena
- Date: 1997
- Subjects: Environmental education -- Study and teaching (Elementary) Environmental education -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1512 , http://hdl.handle.net/10962/d1003394
- Description: This research focuses on environmental education in initial teacher education, and is grounded in three interlinked and widely recognised assumptions. First, that education for sustainable living can assist in resolving some environmental problems that are contributing to the environmental crises of sustainability currently facing South Africa and the rest of the world. Second, that education for sustainable living can assist in the establishment of a new environmental ethic that will foster a sustainable way of living. Third, that teacher education is a vital process for the attainment of both. These assumptions inform the aim of this research, which is to explore the potential for the implementation of education for sustainable living, and to identify a strategy for this, for initial teacher education, for senior primary school student teachers in the Western Cape. The strategy is derived following the grounded theory approach, developed through the case study method. In the process of identifying the strategy, this study establishes that there are challenges at macro, meso and micro levels that are obstructing the changes necessary for education for sustainable living. Change theory provides the basis for explaining these shortcomings, by helping to identify the barriers that might obstruct the realisation of the changes that are necessary for education for sustainable living. These challenges need to be perceived in the light of overcoming three sets of barriers in the way of the potential implementation of education for sustainable living in teacher education. First are those that can be ascribed to the formal education system that, while clinging to Western, Eurocentric values on the one hand, bave also failed to secure a policy for environmental education on the other. Second are the barriers ascribed to the teacher educators themselves, with the whole notion of their powerlessness at its core. Finally, there are the logistical barriers, which encompass, for example, time and financial constraints. With these barriers as a backdrop, to facilitate the incorporation of environmental education into initial teacher education, the study identifies a need for the development of a strategy to secure that education for sustainable living assumes its rightful place in the curriculum for initial teacher education. This framework emerges from the theory grounded in the interviewees' responses during the research, and from the theory grounded in the literature. Central to this framework is for education for sustainable living to contribute to the realisation of real change, change that would further the transformation of our conflict-riddled and inequitable society towards a more democratic and just one. This thesis demonstrates that the realisation of the changes necessary for education for sustainable living demand a reconstruction of current teacher education in order to secure and to sustain an appropriate and sound education ethic to form the basis of a trans formative teacher education curriculum for sustainable living within initial teacher education. Except formal policy, but central to overcoming these barriers, is the need for professional development programmes for teacher educators. A strategy in this regard, is outlined.
- Full Text:
- Date Issued: 1997
Newsletter of the Self-Employed Womens Union - No.22
- SEWU
- Authors: SEWU
- Date: 1997
- Subjects: SEWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/155037 , vital:39835
- Description: Die Derde Jaarlikse Konferensie van SEWU sal vanaf 22 -24 Julie plaasvind. Dit is die eerste nasionale konferensie vandat SEWU buite die grense van KwaZulu- Natal begin organiseer het. Afgevaardigdes van die Wes-Kaap sal ook by hierdie Konferensie wees. EWU lede sal afgevaardigdes uit hulle eie geledere kies om hulle by hierdie Konferensie te verteenwoordig. Daar is ongeveer 48 SEWU takke waarvan 15 in die KwaZulu-Natal se landelike gebiede is. Een afgevaardigde word vanuit elke 20 opbetaalde lede in ’n tak verkies. Ons verwag tussen 100 en 150 afgevaardigdes.
- Full Text:
- Date Issued: 1997
- Authors: SEWU
- Date: 1997
- Subjects: SEWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/155037 , vital:39835
- Description: Die Derde Jaarlikse Konferensie van SEWU sal vanaf 22 -24 Julie plaasvind. Dit is die eerste nasionale konferensie vandat SEWU buite die grense van KwaZulu- Natal begin organiseer het. Afgevaardigdes van die Wes-Kaap sal ook by hierdie Konferensie wees. EWU lede sal afgevaardigdes uit hulle eie geledere kies om hulle by hierdie Konferensie te verteenwoordig. Daar is ongeveer 48 SEWU takke waarvan 15 in die KwaZulu-Natal se landelike gebiede is. Een afgevaardigde word vanuit elke 20 opbetaalde lede in ’n tak verkies. Ons verwag tussen 100 en 150 afgevaardigdes.
- Full Text:
- Date Issued: 1997
Albany Rugby Football Club , 1997
- Date: 1997
- Subjects: Rugby football -- South Africa -- Eastern Cape -- Photographs , Albany Rugby Football Club -- Photographs
- Type: still image
- Identifier: http://hdl.handle.net/10962/45750 , vital:25544 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PIC/M 6734
- Description: Albany Rugby Football Club 1997. Team photograph with rugby/football players in rugby uniform (green jersey and white shorts, red socks), Team sitting outside a building with brick walls and below a window, Some players have arms around others shoulders, while others have cans or bottles of beer in their hands, Back row (left to right): D. Green, A. Annandale, B. Slabbert, A. Boschoff, L. Classen, C. Player (Coach), A. Mgabe, B. Ackerman, R. Havenga.
- Full Text: false
- Date Issued: 1997
- Date: 1997
- Subjects: Rugby football -- South Africa -- Eastern Cape -- Photographs , Albany Rugby Football Club -- Photographs
- Type: still image
- Identifier: http://hdl.handle.net/10962/45750 , vital:25544 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , PIC/M 6734
- Description: Albany Rugby Football Club 1997. Team photograph with rugby/football players in rugby uniform (green jersey and white shorts, red socks), Team sitting outside a building with brick walls and below a window, Some players have arms around others shoulders, while others have cans or bottles of beer in their hands, Back row (left to right): D. Green, A. Annandale, B. Slabbert, A. Boschoff, L. Classen, C. Player (Coach), A. Mgabe, B. Ackerman, R. Havenga.
- Full Text: false
- Date Issued: 1997
The use of remote sensing and Geographic Information System (GIS) techniques, to interpret savanna ecosystem patterns in the Sabi Sand Game Reserve, Mpumalanga province
- Fortescue, Alexander Kenneth John
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
Termination of psychotherapy : a phenomenological exploration of the therapist's and the patient's experience
- Authors: Schlodder, Michelle Ingrid
- Date: 1997
- Subjects: Psychotherapy -- termination Psychotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3049 , http://hdl.handle.net/10962/d1002558
- Full Text:
- Date Issued: 1997
- Authors: Schlodder, Michelle Ingrid
- Date: 1997
- Subjects: Psychotherapy -- termination Psychotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3049 , http://hdl.handle.net/10962/d1002558
- Full Text:
- Date Issued: 1997
Title not specified
- Performer not specified, Tracey, Andrew T N
- Authors: Performer not specified , Tracey, Andrew T N
- Date: 1997
- Subjects: Nyankole (African people) -- Uganda , Music -- Religious aspects , Fiddle tunes , Harp , Drum music , Sub-Saharan African music , Africa Uganda Ankole f-ug
- Language: English
- Type: sound recordings , field recordings , Sound recording material
- Identifier: http://hdl.handle.net/10962/93387 , vital:30875 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC027-01
- Description: Church song accompanied by the endingidi fiddle, harp and drum.
- Full Text: false
- Date Issued: 1997
- Authors: Performer not specified , Tracey, Andrew T N
- Date: 1997
- Subjects: Nyankole (African people) -- Uganda , Music -- Religious aspects , Fiddle tunes , Harp , Drum music , Sub-Saharan African music , Africa Uganda Ankole f-ug
- Language: English
- Type: sound recordings , field recordings , Sound recording material
- Identifier: http://hdl.handle.net/10962/93387 , vital:30875 , International Library of African Music, Rhodes University, Grahamstown, South Africa , ATC027-01
- Description: Church song accompanied by the endingidi fiddle, harp and drum.
- Full Text: false
- Date Issued: 1997
An evaluation of small scale open cast mining of UG2 in the Bushveld complex
- Authors: Mooney, David G
- Date: 1997
- Subjects: Platinum mines and mining -- South Africa , Strip mining -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4943 , http://hdl.handle.net/10962/d1005555 , Platinum mines and mining -- South Africa , Strip mining -- South Africa
- Description: The current weak state of the platinum market, as well as the large inventory of platinum group metals held by Russia, necessitates that the South African platinum mining industry must carefully evaluate the benefits and disadvantage of small-scale mining of shallow, open castable ore resources. Until the late 1980's, these resources were ignored due to the metallurgical complexities of treating oxidized ore, as well as the mind set that existed within the South African mining industry which militated against open cast mining in the Bushveld. During the latter part of the 1980's and early 1990's, advances in the metallurgical treatment of oxidized ore, specifically the UG2, as well as operational problems, created the impetus to begin the exploitation of these resources. Small-scale open cast mining has become viable due to the development of suitable mining methods that facilitate mining practices acceptable to the Department of Mineral and Energy Affairs, in terms of environmental legislation. Metallurgical advances and growing experience, especially with respect to the UG2, enables reasonable platinum group metals recovery from oxidized ore. The problems experienced in doing this can, and are being overcome. With growing public awareness of environmental issues, particularly related to the mining industry, the requirement to ensure that the small-scale open cast mine site is well managed is paramount. A methodology for the evaluation is presented along with a case study of a small-scale UG2 open cast pit. Evidence is presented that shows that these small-scale open cast mining operations are extremely profitable and require minimal capital expenditure. However, caution is advised when evaluating Merensky Reef open cast operations because of the problems that they present.
- Full Text:
- Date Issued: 1997
- Authors: Mooney, David G
- Date: 1997
- Subjects: Platinum mines and mining -- South Africa , Strip mining -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4943 , http://hdl.handle.net/10962/d1005555 , Platinum mines and mining -- South Africa , Strip mining -- South Africa
- Description: The current weak state of the platinum market, as well as the large inventory of platinum group metals held by Russia, necessitates that the South African platinum mining industry must carefully evaluate the benefits and disadvantage of small-scale mining of shallow, open castable ore resources. Until the late 1980's, these resources were ignored due to the metallurgical complexities of treating oxidized ore, as well as the mind set that existed within the South African mining industry which militated against open cast mining in the Bushveld. During the latter part of the 1980's and early 1990's, advances in the metallurgical treatment of oxidized ore, specifically the UG2, as well as operational problems, created the impetus to begin the exploitation of these resources. Small-scale open cast mining has become viable due to the development of suitable mining methods that facilitate mining practices acceptable to the Department of Mineral and Energy Affairs, in terms of environmental legislation. Metallurgical advances and growing experience, especially with respect to the UG2, enables reasonable platinum group metals recovery from oxidized ore. The problems experienced in doing this can, and are being overcome. With growing public awareness of environmental issues, particularly related to the mining industry, the requirement to ensure that the small-scale open cast mine site is well managed is paramount. A methodology for the evaluation is presented along with a case study of a small-scale UG2 open cast pit. Evidence is presented that shows that these small-scale open cast mining operations are extremely profitable and require minimal capital expenditure. However, caution is advised when evaluating Merensky Reef open cast operations because of the problems that they present.
- Full Text:
- Date Issued: 1997
The honeybees, Apis mellifera Linnaeus (Hymenoptera: Apidae) of woodland savanna of southeastern Africa
- Radloff, Sarah E, Hepburn, H Randall, Villet, Martin H
- Authors: Radloff, Sarah E , Hepburn, H Randall , Villet, Martin H
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6829 , http://hdl.handle.net/10962/d1012341
- Description: The morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to identify discrete populations in the southeastern woodland savanna of Africa. A discrete population in Mozambique is classified as A. m. litorea Smith, a second in Zimbabwe as A. m. scutellata Lepeletier and a third group in southwestern Zambia as A.m. adansonii Latreille. A zone of introgression between the last two subspecies occurs in south-central Zambia and in the Zambezi Valley.
- Full Text:
- Date Issued: 1997
- Authors: Radloff, Sarah E , Hepburn, H Randall , Villet, Martin H
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6829 , http://hdl.handle.net/10962/d1012341
- Description: The morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus, were analysed by multivariate methods to identify discrete populations in the southeastern woodland savanna of Africa. A discrete population in Mozambique is classified as A. m. litorea Smith, a second in Zimbabwe as A. m. scutellata Lepeletier and a third group in southwestern Zambia as A.m. adansonii Latreille. A zone of introgression between the last two subspecies occurs in south-central Zambia and in the Zambezi Valley.
- Full Text:
- Date Issued: 1997
A comparative photostability study of four propyl piperzine-substituted phenothiazines
- Authors: Drummond, Patricia Mary
- Date: 1997
- Subjects: Phenothiazine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3756 , http://hdl.handle.net/10962/d1003234 , Phenothiazine
- Description: Four structurally related phenothiazines available in South Africa in a variety of dosage forms and as fine chemicals were investigated to ascertain whether their structural differences in terms of the 2-chloro-/ trifluoromethyl-substituents on the phenothiazine nucleus and the methyl-/ ß-hydroxethyl groups on the piperazine ring accouning for the differences in pharmacological activity can be correlated with their photostability².The four propyl piperazine-substituted derivatives are ranked in the following decreasing order of neuroleptic activity: fluphenazine> trifluoperazine> perphenazine > rochlorperazine. In order to assess their photostability an HPLC method was developed and validated for linearity, accuracy and precision, selectivity, limit of detection and quantitation and ruggedness. Preliminary solution photostudies under controlled light conditions (UV, sunlight, fluorescent light) indicated that the rate of degradation followed first-order kinetics with perphenazine the most susceptible to.photodegradation under all light conditions studied. In vitro and in vivo metabolism yielding the 5-sulphoxide and its reported presence on decomposition of the phenothiazines25 led to the development of a synthetic procedure suitable for the sutphoxides of all four derivatives based on the method proposed by Owens et al. in order to provide standards for comparison in the photostudies⁷. Since ICH regulations require that impurities> 0.1 % are examined and identified⁷⁴ and semi-preparative isolation of photoproducts proved unsuccessful, LC-MS having been well documented for structural.elucidation⁷⁵ ⁷⁵ ⁷⁶ ⁷⁷ was used to characterize solution (UV, sunlight, fluorescent light) and preliminary solid (UV) photostudies. The chloroderivatives underwent dechlorination and sulphoxidation with subsequent photosubstitution in the case of prochlorperazine to yield the 2-hydroxy derivative and sulphoxidation of the dechloro-derivative of perphenazine. The sulphoxides of both trifluoperazine and fluphenazine were formed with further oxidation to the respective sulphones occurring. Preliminary solid state (UV) photostudies showed fluphenazine to be the least stable with 30.71 % degradation as opposed to 7.57% for prochlorperazine, 4.28% for perphenazine and 7.10% for trifluoperazine witn sulphoxidation observed to be. the major degradation pathway. Since in vitro metabolism of perazine derivatives is reported to occur via N-oxidation, N-demethylation, sulphoxidation and aromatic hydroxylation¹⁸ it does appear that there is some correlation between metabolic and photoproducts. However the fact that solution (UV) photostudies indicates trifluoperazine to be the most and perphenazine the least stable does not concur with the proposed order of pharmacological activity.
- Full Text:
- Date Issued: 1997
- Authors: Drummond, Patricia Mary
- Date: 1997
- Subjects: Phenothiazine
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3756 , http://hdl.handle.net/10962/d1003234 , Phenothiazine
- Description: Four structurally related phenothiazines available in South Africa in a variety of dosage forms and as fine chemicals were investigated to ascertain whether their structural differences in terms of the 2-chloro-/ trifluoromethyl-substituents on the phenothiazine nucleus and the methyl-/ ß-hydroxethyl groups on the piperazine ring accouning for the differences in pharmacological activity can be correlated with their photostability².The four propyl piperazine-substituted derivatives are ranked in the following decreasing order of neuroleptic activity: fluphenazine> trifluoperazine> perphenazine > rochlorperazine. In order to assess their photostability an HPLC method was developed and validated for linearity, accuracy and precision, selectivity, limit of detection and quantitation and ruggedness. Preliminary solution photostudies under controlled light conditions (UV, sunlight, fluorescent light) indicated that the rate of degradation followed first-order kinetics with perphenazine the most susceptible to.photodegradation under all light conditions studied. In vitro and in vivo metabolism yielding the 5-sulphoxide and its reported presence on decomposition of the phenothiazines25 led to the development of a synthetic procedure suitable for the sutphoxides of all four derivatives based on the method proposed by Owens et al. in order to provide standards for comparison in the photostudies⁷. Since ICH regulations require that impurities> 0.1 % are examined and identified⁷⁴ and semi-preparative isolation of photoproducts proved unsuccessful, LC-MS having been well documented for structural.elucidation⁷⁵ ⁷⁵ ⁷⁶ ⁷⁷ was used to characterize solution (UV, sunlight, fluorescent light) and preliminary solid (UV) photostudies. The chloroderivatives underwent dechlorination and sulphoxidation with subsequent photosubstitution in the case of prochlorperazine to yield the 2-hydroxy derivative and sulphoxidation of the dechloro-derivative of perphenazine. The sulphoxides of both trifluoperazine and fluphenazine were formed with further oxidation to the respective sulphones occurring. Preliminary solid state (UV) photostudies showed fluphenazine to be the least stable with 30.71 % degradation as opposed to 7.57% for prochlorperazine, 4.28% for perphenazine and 7.10% for trifluoperazine witn sulphoxidation observed to be. the major degradation pathway. Since in vitro metabolism of perazine derivatives is reported to occur via N-oxidation, N-demethylation, sulphoxidation and aromatic hydroxylation¹⁸ it does appear that there is some correlation between metabolic and photoproducts. However the fact that solution (UV) photostudies indicates trifluoperazine to be the most and perphenazine the least stable does not concur with the proposed order of pharmacological activity.
- Full Text:
- Date Issued: 1997
Die ontwikkeling van 'n plattelandse tak van die ACVV 1900-1996
- Authors: Du Plessis, Alette Marjorie
- Date: 1997
- Subjects: Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Language: Afrikaans
- Type: Thesis , Masters , MSocSc
- Identifier: vital:694 , http://hdl.handle.net/10962/d1006387 , Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Description: Die ACVV is een van die oudste gesinsorgorganisasies in Suid-Afrika en die oudste vrou-welsynsvereniging. Die organisasie is in 1904 gestig, maar dit word bewys dat dit in werklikheid ouer is. Die ontstaan is die gevolg van noodlenigingswerk wat in sovele Kaaplandse dorpe en stede aangepak is deur die Afrikaanse vroue om sover moontlik die smarte van die Anglo-Boere-oorlog te verlig. Dit was veral in die jare 1900 en 1902 toe plaaslike komitees in verskeie dorpe gestig is om eetware, klere en leesstof aan die krygsgevangenes in die kamp te stuur en later aan die vroue in konsentrasiekampe. Hieruit kan afgelei word dat die organisasie ontstaan het met oorlewing as oogmerk. Toe die oorlog verby is, het die begeerte posgevat om van hierdie komitees iets blywends te maak. Lambrechts en Theron (1959:31) bepaal dat daar drie tydperke onderskei word by die nagaan van die werksaamhede van die ACVV. In die bestudering van die plaaslike omstandighede word die stelling as waar bewys, maar word die tydperke aangepas om die situasie in 'n wyer spektrum waar te neem. Die eerste tydperk word hoofsaaklik gekenmerk deur die groei van die vereniging en die reelings wat getref is vir die doeltreffende organisasie van die werk wat verrig is deur vrywillige werkers. Die tweede tydperk val saam met 'n algehele nuwe benadering teenoor welsynswerk wat gevloei het uit die vermeerderde kennis en studie van Sosiale Wetenskappe en die vraagstuk van verarming in Suid-Afrika na die jare van droogte en depressie. 'n Derde tydperk is geëidentifiseer waarin die land tred gehou het met die wereldtendens waarin die staat 'n groter aandeel in welsynsdienste begin neem het. 'n Toenemende toepassing van die beleid van staatshulp aan partikuliere organisasies is 'n erkenning van staatsweë dat daar bepaalde take is wat beter deur hierdie organisasies vervul kan word. Dit het ACW-takke in staat gestel om maatskaplike werkers aan te stel in gesubsidieerde poste. Die ACVV se dienste het gedurig ontwikkeling getoon en het noodleniging, gesinsorgdienste, groepdienste en residensiële sorg ingesluit. Dienste het sekondêr ontwikkel en baie klem is op bejaardesorg geplaas wat onder andere die oprigting en bestuur van tehuise en dienssentrums tot gevolg gehad het. Gesinsorgwerk vorm die eintlike kern van die werksaamhede van die ACVV, want al sy ondernemings het ten doel die bevordering van 'n gesonde gesinslewe. Dienste van die vereniging aan die individuele gesinslid het steeds ten doel om beter by sy gesin, en gevolglik ook beter by die samelewing aan te pas. 'n Duidelike ontwikkeling word beskryf wat vanaf 1990 tot 'n punt van verdere veranderinge gedryf word deur omstandighede buite die ACVV. Die belangrikste hiervan is 'n dramatiese verandering in regeringsbeleid waarby die ACVV moes aansluit. Dit het wesentlike aanpassings meegebring op die gebied van werksarea en die kliêntesisteem, aangesien die ACVV in die verlede hoofsaaklik in die behoeftes van die blanke kultuurgroep voorsien het. Later het subsidievereistes die vereniging verhoed om buite hierdie beperkings te werk. Die aanpassings het egter nie tot gevolg gehad dat die vereniging doelstellings, waardes en norme moes laat vaar nie. Verskeie rolspelers is betrokke by praktiese en basiese dienslewering tot besluitneming op die hoogste vlak. Die ACVV se struktuur het grootliks dieselfde gebly met die Kongres as hoogste gesag. Die dienste van die Hoofbestuur het sodanig uitgebrei dat dit leiding kon bied aan takke op grondvlak. Dit is deurgaans duidelik dat die vrywillige werker binne die organisasie die kern en basis vorm waarop die vereniging voortbestaan. Die ACVV sal in die toekoms steeds In rol het om te vervul in 'n veranderde omgewing wat uitdagings bied vir dienslewering en waar uitgebreide behoeftes ten opsigte van maatskaplike ontwikkeling bestaan
- Full Text:
- Date Issued: 1997
- Authors: Du Plessis, Alette Marjorie
- Date: 1997
- Subjects: Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Language: Afrikaans
- Type: Thesis , Masters , MSocSc
- Identifier: vital:694 , http://hdl.handle.net/10962/d1006387 , Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Description: Die ACVV is een van die oudste gesinsorgorganisasies in Suid-Afrika en die oudste vrou-welsynsvereniging. Die organisasie is in 1904 gestig, maar dit word bewys dat dit in werklikheid ouer is. Die ontstaan is die gevolg van noodlenigingswerk wat in sovele Kaaplandse dorpe en stede aangepak is deur die Afrikaanse vroue om sover moontlik die smarte van die Anglo-Boere-oorlog te verlig. Dit was veral in die jare 1900 en 1902 toe plaaslike komitees in verskeie dorpe gestig is om eetware, klere en leesstof aan die krygsgevangenes in die kamp te stuur en later aan die vroue in konsentrasiekampe. Hieruit kan afgelei word dat die organisasie ontstaan het met oorlewing as oogmerk. Toe die oorlog verby is, het die begeerte posgevat om van hierdie komitees iets blywends te maak. Lambrechts en Theron (1959:31) bepaal dat daar drie tydperke onderskei word by die nagaan van die werksaamhede van die ACVV. In die bestudering van die plaaslike omstandighede word die stelling as waar bewys, maar word die tydperke aangepas om die situasie in 'n wyer spektrum waar te neem. Die eerste tydperk word hoofsaaklik gekenmerk deur die groei van die vereniging en die reelings wat getref is vir die doeltreffende organisasie van die werk wat verrig is deur vrywillige werkers. Die tweede tydperk val saam met 'n algehele nuwe benadering teenoor welsynswerk wat gevloei het uit die vermeerderde kennis en studie van Sosiale Wetenskappe en die vraagstuk van verarming in Suid-Afrika na die jare van droogte en depressie. 'n Derde tydperk is geëidentifiseer waarin die land tred gehou het met die wereldtendens waarin die staat 'n groter aandeel in welsynsdienste begin neem het. 'n Toenemende toepassing van die beleid van staatshulp aan partikuliere organisasies is 'n erkenning van staatsweë dat daar bepaalde take is wat beter deur hierdie organisasies vervul kan word. Dit het ACW-takke in staat gestel om maatskaplike werkers aan te stel in gesubsidieerde poste. Die ACVV se dienste het gedurig ontwikkeling getoon en het noodleniging, gesinsorgdienste, groepdienste en residensiële sorg ingesluit. Dienste het sekondêr ontwikkel en baie klem is op bejaardesorg geplaas wat onder andere die oprigting en bestuur van tehuise en dienssentrums tot gevolg gehad het. Gesinsorgwerk vorm die eintlike kern van die werksaamhede van die ACVV, want al sy ondernemings het ten doel die bevordering van 'n gesonde gesinslewe. Dienste van die vereniging aan die individuele gesinslid het steeds ten doel om beter by sy gesin, en gevolglik ook beter by die samelewing aan te pas. 'n Duidelike ontwikkeling word beskryf wat vanaf 1990 tot 'n punt van verdere veranderinge gedryf word deur omstandighede buite die ACVV. Die belangrikste hiervan is 'n dramatiese verandering in regeringsbeleid waarby die ACVV moes aansluit. Dit het wesentlike aanpassings meegebring op die gebied van werksarea en die kliêntesisteem, aangesien die ACVV in die verlede hoofsaaklik in die behoeftes van die blanke kultuurgroep voorsien het. Later het subsidievereistes die vereniging verhoed om buite hierdie beperkings te werk. Die aanpassings het egter nie tot gevolg gehad dat die vereniging doelstellings, waardes en norme moes laat vaar nie. Verskeie rolspelers is betrokke by praktiese en basiese dienslewering tot besluitneming op die hoogste vlak. Die ACVV se struktuur het grootliks dieselfde gebly met die Kongres as hoogste gesag. Die dienste van die Hoofbestuur het sodanig uitgebrei dat dit leiding kon bied aan takke op grondvlak. Dit is deurgaans duidelik dat die vrywillige werker binne die organisasie die kern en basis vorm waarop die vereniging voortbestaan. Die ACVV sal in die toekoms steeds In rol het om te vervul in 'n veranderde omgewing wat uitdagings bied vir dienslewering en waar uitgebreide behoeftes ten opsigte van maatskaplike ontwikkeling bestaan
- Full Text:
- Date Issued: 1997
Regional and local economic development strategies in the Eastern Cape and guidelines for future development
- Nel, E L
- Authors: Nel, E L
- Date: 1997
- Subjects: Community development -- South Africa -- Eastern Cape Case studies Community development Community development -- South Africa -- Eastern Cape Eastern Cape (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4848 , http://hdl.handle.net/10962/d1005524
- Description: Local Economic Development (LED) is an applied economic development strategy which seeks to address site-specific needs through locally appropriate solutions. In this thesis, the faith being accorded to the potential of LED in South Africa is critically examined. The study is based on a detailed examination of the experience of regional development and several emerging cases of LED in the Eastern Cape Province of South Africa. High levels of poverty and unemployment necessitate and justify innovative approaches to address such problems. The thesis examines the potential of LED strategies and identifies applied policy guidelines which can help address the Province's development needs. The theoretical framework of this research is based on a critical examination of international and South African literature dealing with development issues, LED and localities theory. A detailed documentary examination of early LED endeavours and the experience of regional development in the present century was undertaken. Results suggest that LED is not a new concept and that regional development, through its political bias, achieved only limited success. Contemporary examples of LED were identified and examined through detailed site-specific investigations. This was carried out through the use of semistructured interviews supplemented by participatory rural appraisal and questionnaire surveys which served as a means to triangulate the results. The research findings indicate that regional development, as applied in the study area, did not lead to the establishment of a permanent industrial base. In terms of the concept of LED, it is apparent that it has allowed for socio-political empowerment but has only improved economic conditions in the more well-endowed case-studies. In these areas, positive antecedent conditions and the key role played by community supportive nongovernmental organizations is apparent. Despite the limited degree of success which many initiatives attain, the thesis regards LED as a development alternative for areas which are unlikely to draw in external investment. Some of the key contributions of the thesis include the advancement of a refined typology of LED, the development of a research schedule to investigate and assess LED initiatives and the postulation of appropriate development guidelines and theoretical constructs.
- Full Text:
- Date Issued: 1997
- Authors: Nel, E L
- Date: 1997
- Subjects: Community development -- South Africa -- Eastern Cape Case studies Community development Community development -- South Africa -- Eastern Cape Eastern Cape (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4848 , http://hdl.handle.net/10962/d1005524
- Description: Local Economic Development (LED) is an applied economic development strategy which seeks to address site-specific needs through locally appropriate solutions. In this thesis, the faith being accorded to the potential of LED in South Africa is critically examined. The study is based on a detailed examination of the experience of regional development and several emerging cases of LED in the Eastern Cape Province of South Africa. High levels of poverty and unemployment necessitate and justify innovative approaches to address such problems. The thesis examines the potential of LED strategies and identifies applied policy guidelines which can help address the Province's development needs. The theoretical framework of this research is based on a critical examination of international and South African literature dealing with development issues, LED and localities theory. A detailed documentary examination of early LED endeavours and the experience of regional development in the present century was undertaken. Results suggest that LED is not a new concept and that regional development, through its political bias, achieved only limited success. Contemporary examples of LED were identified and examined through detailed site-specific investigations. This was carried out through the use of semistructured interviews supplemented by participatory rural appraisal and questionnaire surveys which served as a means to triangulate the results. The research findings indicate that regional development, as applied in the study area, did not lead to the establishment of a permanent industrial base. In terms of the concept of LED, it is apparent that it has allowed for socio-political empowerment but has only improved economic conditions in the more well-endowed case-studies. In these areas, positive antecedent conditions and the key role played by community supportive nongovernmental organizations is apparent. Despite the limited degree of success which many initiatives attain, the thesis regards LED as a development alternative for areas which are unlikely to draw in external investment. Some of the key contributions of the thesis include the advancement of a refined typology of LED, the development of a research schedule to investigate and assess LED initiatives and the postulation of appropriate development guidelines and theoretical constructs.
- Full Text:
- Date Issued: 1997
Exploitation of the bait organism Upogebia africana (Crustacea: Anomura) in the Knysna estuary
- Authors: Cretchley, Robyn
- Date: 1997
- Subjects: Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5691 , http://hdl.handle.net/10962/d1005377 , Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Description: In South African estuaries the anomuran mud prawn, Upogebia africana (Ortmann), is the main organism exploited as bait by recreational and subsistence anglers. In the Knysna estuary, three groups of bait collectors were identified on the basis of their source of income: subsistence fishermen who rely on bait-collecting and fishing for their income, supplementary anglers who catch fish to supplement their income and leisure anglers who draw no income from fishing. Two groups were identified based on the methods used: lelsure anglers who collect bait using a prawn pusher or pump and fish using a fishing rod and tackle, and non-leisure anglers who collect mud prawns using tin cans and fish with handlines. The hypothesis was erected that bait-collecting does not affect the U africana populations in the Knysna estuary. The approach adopted was to assess the distribution, density, population structure and reproductive patterns of the bait stock and to estimate the intensity of bait collection, to test the validity of the hypothesis. U africana has an extensive distribution, occupying 62 % of the available intertidal area of the Knysna estuary. Mud prawns have a broad intertidal distribution from the high water level (Spartina zone) to the shallow subtidal. The density, biomass and population structure of the mud prawns vary significantly with distance up the estuary and with tidal height on each shore. The Invertebrate Reserve supports very low densities of U africana (x = 11.7 m⁻²), whereas a relatively inaccessible centre bank in the middle reaches of the estuary appears to be a very effective natural mud prawn reserve as it supports the highest densities (x = 176.5m⁻²). The mud prawn stock of the estuary is estimated to be 2.19 x 108 prawns (82.7 tonnes dry mass). The numbers of bait collectors present per mudbank is highest on public holidays (x = 34) and higher during the summer holidays (x = 16) than during the winter (x = 4). A total of 1.858 x 106 U africana or 700.53 kg (dry mass) are removed by bait collectors annually from the 6 popular bait-collecting sites studied. This represents 8.49 % of the mud prawn stocks at these sites and 0.85 % of the entire estuary stock. 85 % of the U africana taken as bait annually, is removed by the 77.12 % of bait collectors who are non-leisure anglers. Recreational or leisure anglers are responsible for removing 14.2 %. The reproduction of female U africana in the Knysna estuary is seasonal and occurs from late July to April. There is evidence that this breeding season consists of two merging breeding cycles. The largest percentage (63 %) of ovigerous females is found in the middle reaches of the Knysna estuary at the Oyster Bank where the highest numbers of stage 1 larvae (165 m⁻³) are released. Larvae were exported from the estuary on the crepuscular ebb tide with peaks in abundance of nearly 1500 m⁻³ in November 1995 and January 1996. Although numbers caught are not significantly higher, larvae are nearly twice as abundant on crepuscular neap tides following a new moon (waxing quarter) than on those following a full moon (waning quarter). Recruitment of juvenile U africana to populations in the estuary was highest in December (45 m⁻²) and decreased over the summer. The highest numbers of recruits (31 m⁻²) were found at those sites closest to the mouth or on the main channel. Recruitment to the Leisure Isle and Thesens sites which are intensively exploited by bait collectors is high (20 - 32 m⁻²). The number of juveniles recruiting to U africana populations is estimated to be four times as high as the numbers of mud prawns taken by bait collectors. Legal methods of bait collection used in the Knysna estuary by the majority of anglers appear to cause minimal sediment disturbance and are not likely to affect the associated infauna. Illegal bait-collecting methods are however highly destructive and must be prohibited. It is concluded that the null hypothesis is acceptable, as mud prawn stocks of the Knysna estuary are not over-exploited and appear to be naturally regulated. The recruitment rate of juvenile U africana is estimated to be sufficiently high to sustain the present levels of exploitation.
- Full Text:
- Date Issued: 1997
- Authors: Cretchley, Robyn
- Date: 1997
- Subjects: Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5691 , http://hdl.handle.net/10962/d1005377 , Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Description: In South African estuaries the anomuran mud prawn, Upogebia africana (Ortmann), is the main organism exploited as bait by recreational and subsistence anglers. In the Knysna estuary, three groups of bait collectors were identified on the basis of their source of income: subsistence fishermen who rely on bait-collecting and fishing for their income, supplementary anglers who catch fish to supplement their income and leisure anglers who draw no income from fishing. Two groups were identified based on the methods used: lelsure anglers who collect bait using a prawn pusher or pump and fish using a fishing rod and tackle, and non-leisure anglers who collect mud prawns using tin cans and fish with handlines. The hypothesis was erected that bait-collecting does not affect the U africana populations in the Knysna estuary. The approach adopted was to assess the distribution, density, population structure and reproductive patterns of the bait stock and to estimate the intensity of bait collection, to test the validity of the hypothesis. U africana has an extensive distribution, occupying 62 % of the available intertidal area of the Knysna estuary. Mud prawns have a broad intertidal distribution from the high water level (Spartina zone) to the shallow subtidal. The density, biomass and population structure of the mud prawns vary significantly with distance up the estuary and with tidal height on each shore. The Invertebrate Reserve supports very low densities of U africana (x = 11.7 m⁻²), whereas a relatively inaccessible centre bank in the middle reaches of the estuary appears to be a very effective natural mud prawn reserve as it supports the highest densities (x = 176.5m⁻²). The mud prawn stock of the estuary is estimated to be 2.19 x 108 prawns (82.7 tonnes dry mass). The numbers of bait collectors present per mudbank is highest on public holidays (x = 34) and higher during the summer holidays (x = 16) than during the winter (x = 4). A total of 1.858 x 106 U africana or 700.53 kg (dry mass) are removed by bait collectors annually from the 6 popular bait-collecting sites studied. This represents 8.49 % of the mud prawn stocks at these sites and 0.85 % of the entire estuary stock. 85 % of the U africana taken as bait annually, is removed by the 77.12 % of bait collectors who are non-leisure anglers. Recreational or leisure anglers are responsible for removing 14.2 %. The reproduction of female U africana in the Knysna estuary is seasonal and occurs from late July to April. There is evidence that this breeding season consists of two merging breeding cycles. The largest percentage (63 %) of ovigerous females is found in the middle reaches of the Knysna estuary at the Oyster Bank where the highest numbers of stage 1 larvae (165 m⁻³) are released. Larvae were exported from the estuary on the crepuscular ebb tide with peaks in abundance of nearly 1500 m⁻³ in November 1995 and January 1996. Although numbers caught are not significantly higher, larvae are nearly twice as abundant on crepuscular neap tides following a new moon (waxing quarter) than on those following a full moon (waning quarter). Recruitment of juvenile U africana to populations in the estuary was highest in December (45 m⁻²) and decreased over the summer. The highest numbers of recruits (31 m⁻²) were found at those sites closest to the mouth or on the main channel. Recruitment to the Leisure Isle and Thesens sites which are intensively exploited by bait collectors is high (20 - 32 m⁻²). The number of juveniles recruiting to U africana populations is estimated to be four times as high as the numbers of mud prawns taken by bait collectors. Legal methods of bait collection used in the Knysna estuary by the majority of anglers appear to cause minimal sediment disturbance and are not likely to affect the associated infauna. Illegal bait-collecting methods are however highly destructive and must be prohibited. It is concluded that the null hypothesis is acceptable, as mud prawn stocks of the Knysna estuary are not over-exploited and appear to be naturally regulated. The recruitment rate of juvenile U africana is estimated to be sufficiently high to sustain the present levels of exploitation.
- Full Text:
- Date Issued: 1997