English in Africa 2000 : towards a new millennium : inaugural lecture delivered at Rhodes University
- Authors: Walters, Paul S
- Date: 1988
- Subjects: Molteno Project , English language -- Study and teaching -- South Africa , English language -- Usage -- South Africa
- Language: English
- Type: Text
- Identifier: vital:678 , http://hdl.handle.net/10962/d1020747 , ISBN 0868101680
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1988
English in Africa 2000 : towards a new millennium : inaugural lecture delivered at Rhodes University
- Authors: Walters, Paul S
- Date: 1988
- Subjects: Molteno Project , English language -- Study and teaching -- South Africa , English language -- Usage -- South Africa
- Language: English
- Type: Text
- Identifier: vital:678 , http://hdl.handle.net/10962/d1020747 , ISBN 0868101680
- Description: Inaugural lecture delivered at Rhodes University , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1988
Environmental requirements for the hatchery rearing of African catfish Clarias Gariepinus (Pisces: Clariidae) larvae and juveniles
- Britz, P J (Peter Jacobus), 1959-
- Authors: Britz, P J (Peter Jacobus), 1959-
- Date: 1988
- Subjects: Catfishes -- Africa , Fish culture , Clariidae , Clarias
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5188 , http://hdl.handle.net/10962/d1001964 , Catfishes -- Africa , Fish culture , Clariidae , Clarias
- Description: Inadequate seed production has historically been a factor limiting the commercial culture of Clarias gariepinus. The need to determine the environmental requirements of larvae was identified, in order to facilitate their successful mass rearing in hatcheries. The effects of key environmental factors on the growth, survival and aspects of the behaviour of C. gariepinus larvae and juveniles were investigated under controlled conditions. A strong emphasis was placed on the interpretation of the observed responses in terms of the natural history of the animal. Larvae were obtained by artificially inducing and spawning feral adult broodfish. Larval growth rates were highest in the temperature range 26-33ºC, with a peak at 30ºC. Survival of larvae was high between 22 and 33ºC. The final temperature preferendum of juveniles, determined in a thermal gradient was 30ºC, and it was concluded that this temperature is probably optimal for most of the physiological processes of the animal. Larvae and juveniles displayed strong negative phototaxis. When reared under different photoperiod regimes, larval growth increased with longer dark periods, however a similar rate of mortality was recorded in all photoperiod treatments. The provision of cover was found to enhance larval growth under conditions of continual light (24L/OD), however under conditions of continual darkness (OL/24D) similar growth rates were recorded regardless of the presence or absence of cover. All growth rates in continual darkness (OL/24D) were higher than those in continual light (24L/OD), regardless of whether cover was provided or not. It was concluded that a OL/24D photoperiod is optimal for larval rearing. At salinities between 0 and 5% similar growth and mortality rates of larvae were recorded. At 7.5 % larval growth and survival rates were lower, and at 10 % all larvae died within 48 hours. The 96h-LCSO for unionised ammonia was found to be 2.3 mg/l. The cytological effects of unionised ammonia were evident as degenerative changes in the gill and liver tissues. In an investigation of tank hygiene, it was found that larval growth and survival rates were highest in tanks not cleaned at all. As the frequency of tank cleaning increased, the growth and survival rates of larvae decreased. When reared at densities ranging from 45-450/1, larval growth was found to be density dependent. A model of hatchery productivity (number larvae of standard size produced/time/vol.) was developed based on the density dependent nature of larval growth. The model predicts that maximum productivity, will be achieved at a rearing density of 1400/1. The high growth and survival rates obtained over a broad range of each environmental parameter investigated serve to explain how larvae survive and grow in their unstable floodplain habitat in nature. The broad environmental tolerances of C. gariepinus are of benefit with respect to the culture of larvae, as successful larval rearing is possible over a fairly wide range of environmental conditions.
- Full Text:
- Date Issued: 1988
- Authors: Britz, P J (Peter Jacobus), 1959-
- Date: 1988
- Subjects: Catfishes -- Africa , Fish culture , Clariidae , Clarias
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5188 , http://hdl.handle.net/10962/d1001964 , Catfishes -- Africa , Fish culture , Clariidae , Clarias
- Description: Inadequate seed production has historically been a factor limiting the commercial culture of Clarias gariepinus. The need to determine the environmental requirements of larvae was identified, in order to facilitate their successful mass rearing in hatcheries. The effects of key environmental factors on the growth, survival and aspects of the behaviour of C. gariepinus larvae and juveniles were investigated under controlled conditions. A strong emphasis was placed on the interpretation of the observed responses in terms of the natural history of the animal. Larvae were obtained by artificially inducing and spawning feral adult broodfish. Larval growth rates were highest in the temperature range 26-33ºC, with a peak at 30ºC. Survival of larvae was high between 22 and 33ºC. The final temperature preferendum of juveniles, determined in a thermal gradient was 30ºC, and it was concluded that this temperature is probably optimal for most of the physiological processes of the animal. Larvae and juveniles displayed strong negative phototaxis. When reared under different photoperiod regimes, larval growth increased with longer dark periods, however a similar rate of mortality was recorded in all photoperiod treatments. The provision of cover was found to enhance larval growth under conditions of continual light (24L/OD), however under conditions of continual darkness (OL/24D) similar growth rates were recorded regardless of the presence or absence of cover. All growth rates in continual darkness (OL/24D) were higher than those in continual light (24L/OD), regardless of whether cover was provided or not. It was concluded that a OL/24D photoperiod is optimal for larval rearing. At salinities between 0 and 5% similar growth and mortality rates of larvae were recorded. At 7.5 % larval growth and survival rates were lower, and at 10 % all larvae died within 48 hours. The 96h-LCSO for unionised ammonia was found to be 2.3 mg/l. The cytological effects of unionised ammonia were evident as degenerative changes in the gill and liver tissues. In an investigation of tank hygiene, it was found that larval growth and survival rates were highest in tanks not cleaned at all. As the frequency of tank cleaning increased, the growth and survival rates of larvae decreased. When reared at densities ranging from 45-450/1, larval growth was found to be density dependent. A model of hatchery productivity (number larvae of standard size produced/time/vol.) was developed based on the density dependent nature of larval growth. The model predicts that maximum productivity, will be achieved at a rearing density of 1400/1. The high growth and survival rates obtained over a broad range of each environmental parameter investigated serve to explain how larvae survive and grow in their unstable floodplain habitat in nature. The broad environmental tolerances of C. gariepinus are of benefit with respect to the culture of larvae, as successful larval rearing is possible over a fairly wide range of environmental conditions.
- Full Text:
- Date Issued: 1988
Explanation in rule-based expert systems
- Authors: Carden, Kenneth John
- Date: 1988
- Subjects: Expert systems (Computer science) Ecology -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4569 , http://hdl.handle.net/10962/d1002034
- Description: The ability of an expert system to explain its reasoning is fundamental to the system's credibility. Explanations become even more vital in systems which use methods of uncertainty propagation. The research documented here describes the development of an explanation sub-system which interfaces with the P.R.O. Expert System Toolkit. This toolkit has been used in the development of three small ecological expert systems. This project has involved adapting the results of research in the field of explanation-generation, to the requirements of the ecologist users. The subsystem contains two major components. The first lists the rules that fired during a consultation. The second component comprises routines responsible for quantifying the effects on the system conclusions of the answers given to questions. These latter routines can be used to perform sensitivity analyses on the answers given. The incorporation of such routines in small expert systems is quite unique
- Full Text:
- Date Issued: 1988
- Authors: Carden, Kenneth John
- Date: 1988
- Subjects: Expert systems (Computer science) Ecology -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4569 , http://hdl.handle.net/10962/d1002034
- Description: The ability of an expert system to explain its reasoning is fundamental to the system's credibility. Explanations become even more vital in systems which use methods of uncertainty propagation. The research documented here describes the development of an explanation sub-system which interfaces with the P.R.O. Expert System Toolkit. This toolkit has been used in the development of three small ecological expert systems. This project has involved adapting the results of research in the field of explanation-generation, to the requirements of the ecologist users. The subsystem contains two major components. The first lists the rules that fired during a consultation. The second component comprises routines responsible for quantifying the effects on the system conclusions of the answers given to questions. These latter routines can be used to perform sensitivity analyses on the answers given. The incorporation of such routines in small expert systems is quite unique
- Full Text:
- Date Issued: 1988
Extractives from six species of Lamiaceae
- Davies-Coleman, Michael Trevor
- Authors: Davies-Coleman, Michael Trevor
- Date: 1988
- Subjects: Lamiaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4532 , http://hdl.handle.net/10962/d1016235
- Description: In continuation of the phytochemical studies of plants belonging to the Lamiaceae (formerly Labiatae) the acetone extractives of six Southern African species from this family have been examined. The genus Syncolostemon has not been investigated before and a new 6- substituted-5 ,6-dihydro-a-pyrone , synrotolide was isolated from S. rotundifolius. The structure of synrotolide was fully elucidated as 6fixii [3'R, 61S-(diacetyloxy)-4 1R, 5 1 8-(dihydroxy)-1~-hepteny~ -5,6-dihydro-2H-pyran- 2-one. Oleanolic acid is the major component of both~ rotundifolius and S. densifloris. The flavonol quercetin was isolated from S. densifloris as its 3, 3', 4' , 7 tetramethyl ether. A further 6-substituted-5,6-dihydro-a-pyrone, boronolide, was obtained from Tetradenia barberae. The structure of boronolide was known but the absolute stereochemistry was unassigned. Chemical degradation established the total structure of this compound as 6R- [1 'R, 2'R, 3's -(trisacetyloxy)heptyl] -5,6-dihydro-2H-pyran-2-one. The chemistry of naturally occuring 6-substituted-5,6-dihydro-apyrones has not as such been previously reviewed and a comprehensive review covering the literature up to June 1987 is presented here. Three known labdane diterpenoids nepetaefuran, hispanalone and dubiin were iso lated from Leonotis nepetaefolia, Ballota africana and L. ocymifolia var. ocymifolia (formerly~ dubia). Both~ nepetaefolia and L. dubia have been examined before. An X-ray analysis of saponified dubiin and a circular dichroism study of 6-deacetyldehydrodubiin and related compounds corroborated the structure of dubiin as 48, 5R, 6R, 8R, 9R, 10R-[6-acetoxy-15,16-epoxy-9-hydroxylabda-13 (16), 14-dien-19, 20- olactoneJ. The chemotaxonomic relationships of the genera Ballota and Leonotis are discussed.
- Full Text:
- Date Issued: 1988
- Authors: Davies-Coleman, Michael Trevor
- Date: 1988
- Subjects: Lamiaceae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4532 , http://hdl.handle.net/10962/d1016235
- Description: In continuation of the phytochemical studies of plants belonging to the Lamiaceae (formerly Labiatae) the acetone extractives of six Southern African species from this family have been examined. The genus Syncolostemon has not been investigated before and a new 6- substituted-5 ,6-dihydro-a-pyrone , synrotolide was isolated from S. rotundifolius. The structure of synrotolide was fully elucidated as 6fixii [3'R, 61S-(diacetyloxy)-4 1R, 5 1 8-(dihydroxy)-1~-hepteny~ -5,6-dihydro-2H-pyran- 2-one. Oleanolic acid is the major component of both~ rotundifolius and S. densifloris. The flavonol quercetin was isolated from S. densifloris as its 3, 3', 4' , 7 tetramethyl ether. A further 6-substituted-5,6-dihydro-a-pyrone, boronolide, was obtained from Tetradenia barberae. The structure of boronolide was known but the absolute stereochemistry was unassigned. Chemical degradation established the total structure of this compound as 6R- [1 'R, 2'R, 3's -(trisacetyloxy)heptyl] -5,6-dihydro-2H-pyran-2-one. The chemistry of naturally occuring 6-substituted-5,6-dihydro-apyrones has not as such been previously reviewed and a comprehensive review covering the literature up to June 1987 is presented here. Three known labdane diterpenoids nepetaefuran, hispanalone and dubiin were iso lated from Leonotis nepetaefolia, Ballota africana and L. ocymifolia var. ocymifolia (formerly~ dubia). Both~ nepetaefolia and L. dubia have been examined before. An X-ray analysis of saponified dubiin and a circular dichroism study of 6-deacetyldehydrodubiin and related compounds corroborated the structure of dubiin as 48, 5R, 6R, 8R, 9R, 10R-[6-acetoxy-15,16-epoxy-9-hydroxylabda-13 (16), 14-dien-19, 20- olactoneJ. The chemotaxonomic relationships of the genera Ballota and Leonotis are discussed.
- Full Text:
- Date Issued: 1988
Feeding by larvae of the American bollworm, Heliothis armigera (Hübner) (Lepidoptera: Noctuidae) on cotton plants
- Van der Walt, Susanna Johanna
- Authors: Van der Walt, Susanna Johanna
- Date: 1988
- Subjects: Cotton -- Diseases and pests , Helicoverpa armigera , Lepidoptera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5622 , http://hdl.handle.net/10962/d1004386 , Cotton -- Diseases and pests , Helicoverpa armigera , Lepidoptera
- Description: H. armigera larvae are a key stage for pest management in conmercial irrigated cotton crops in South Africa. Effective survey methods for detecting larval populations in the field require an understanding of the biology of the larvae, particularly their feeding habits. Their feeding is central to the development of pest threshold levels for the implementation of integrated control programmes. This applies to routine surveys for the larvae as well as to the damage they cause. Biological characteristics of the larvae are described with the emphasis on the identification of the larval instars, which were consistently five in number in both field and laboratory populations. The distribution of H. armigera larvae on cotton plants in the field was examined, but was found to more or less random; had there been a clear preference for any height zones or compass direction this would have been an obvious avenue for improving the survey methods currently in use. Details of field and laboratory investigations of the selection of feeding sites by the larvae are given. The study confirmed a clear preference by the larvae for cotton buds, flowers and bolls (in the thesis collectively called "fruiting forms"), over leaves. There were indications that the larvae selected flowers more readily than buds or bolls. This "preference", however, is shown to be of no practical value for refining survey methods. Damage levels to cotton due to B. armigera are discussed. Both direct losses and indirect losses due to the abortion of fruiting forms are considered. These criteria are inadequate since they do not take into account the ability of cotton plants to compensate for these losses. It is concluded that this compensation by cotton plants should be taken into account in further studies of the pest status of B. armigera.
- Full Text:
- Date Issued: 1988
- Authors: Van der Walt, Susanna Johanna
- Date: 1988
- Subjects: Cotton -- Diseases and pests , Helicoverpa armigera , Lepidoptera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5622 , http://hdl.handle.net/10962/d1004386 , Cotton -- Diseases and pests , Helicoverpa armigera , Lepidoptera
- Description: H. armigera larvae are a key stage for pest management in conmercial irrigated cotton crops in South Africa. Effective survey methods for detecting larval populations in the field require an understanding of the biology of the larvae, particularly their feeding habits. Their feeding is central to the development of pest threshold levels for the implementation of integrated control programmes. This applies to routine surveys for the larvae as well as to the damage they cause. Biological characteristics of the larvae are described with the emphasis on the identification of the larval instars, which were consistently five in number in both field and laboratory populations. The distribution of H. armigera larvae on cotton plants in the field was examined, but was found to more or less random; had there been a clear preference for any height zones or compass direction this would have been an obvious avenue for improving the survey methods currently in use. Details of field and laboratory investigations of the selection of feeding sites by the larvae are given. The study confirmed a clear preference by the larvae for cotton buds, flowers and bolls (in the thesis collectively called "fruiting forms"), over leaves. There were indications that the larvae selected flowers more readily than buds or bolls. This "preference", however, is shown to be of no practical value for refining survey methods. Damage levels to cotton due to B. armigera are discussed. Both direct losses and indirect losses due to the abortion of fruiting forms are considered. These criteria are inadequate since they do not take into account the ability of cotton plants to compensate for these losses. It is concluded that this compensation by cotton plants should be taken into account in further studies of the pest status of B. armigera.
- Full Text:
- Date Issued: 1988
Fest-Quest 87: a survey of visitors to the 1987 Standard Bank Festival of Arts
- Authors: Davies, William J
- Date: 1988
- Subjects: Art festivals -- South Africa Standard Bank National Arts Festival
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2304 , vital:20274 , ISBN 0868101656
- Description: Fest-Quest '87 was an attempt to secure information from visitors to the Standard Bank National Festival of the Arts held in Grahamstown from July 3 to July 11 1987. From the outset, this was an ambitious undertaking especially in view of the kinds of people and the ambient atmosphere associated with nine hectic days of cultural injection and serious literary and artistic discourse, interspersed with revelry and novel experiences; none of which is particularly conducive to filling in a lengthy questionnaire. Nevertheless, the exercise was well worth the effort and a number of lessons have been learned about how such a survey might be better conducted in future. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1988
- Authors: Davies, William J
- Date: 1988
- Subjects: Art festivals -- South Africa Standard Bank National Arts Festival
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2304 , vital:20274 , ISBN 0868101656
- Description: Fest-Quest '87 was an attempt to secure information from visitors to the Standard Bank National Festival of the Arts held in Grahamstown from July 3 to July 11 1987. From the outset, this was an ambitious undertaking especially in view of the kinds of people and the ambient atmosphere associated with nine hectic days of cultural injection and serious literary and artistic discourse, interspersed with revelry and novel experiences; none of which is particularly conducive to filling in a lengthy questionnaire. Nevertheless, the exercise was well worth the effort and a number of lessons have been learned about how such a survey might be better conducted in future. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1988
Fishes of the family Mullidae in the Red Sea, with a key to the species in the Red Sea and the Eastern Mediterranean
- Ben-Tuvia, Adam, Kissil, Geerge Wm
- Authors: Ben-Tuvia, Adam , Kissil, Geerge Wm
- Date: 1988
- Subjects: Mullidae -- Red Sea , Mullidae -- Mediterranean Sea
- Language: English
- Type: Text
- Identifier: vital:15011 , http://hdl.handle.net/10962/d1019744 , ISSN 0073-4381 , ISBN 0-86810-175-3 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 52
- Description: Thirteen species of Mullidae (goatfishes or red mullets) occur in the Red Sea: Mulloides flavolineatus, M. vanicolensis, Parupeneus cyclostomus, P. forsskali, P. heptacanthus, P. macronemus, P. rubescens, Upeneus asymmetricus, U. moluccensis, U. subvittatus (previously known only from the western Pacific), 0. sulphureus, U. tragula and U. vittatus. Descriptions, biological observations and black and white photographs are given for each of these 13 species. Keys are provided to the genera of Mullidae, to the species occurring in the Red Sea, and to the two Mediterranean species of Mullus that have been reported from the Suez Canal. The distinction between the genera Pseudupeneus and Parupeneus is discussed. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1988
- Authors: Ben-Tuvia, Adam , Kissil, Geerge Wm
- Date: 1988
- Subjects: Mullidae -- Red Sea , Mullidae -- Mediterranean Sea
- Language: English
- Type: Text
- Identifier: vital:15011 , http://hdl.handle.net/10962/d1019744 , ISSN 0073-4381 , ISBN 0-86810-175-3 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 52
- Description: Thirteen species of Mullidae (goatfishes or red mullets) occur in the Red Sea: Mulloides flavolineatus, M. vanicolensis, Parupeneus cyclostomus, P. forsskali, P. heptacanthus, P. macronemus, P. rubescens, Upeneus asymmetricus, U. moluccensis, U. subvittatus (previously known only from the western Pacific), 0. sulphureus, U. tragula and U. vittatus. Descriptions, biological observations and black and white photographs are given for each of these 13 species. Keys are provided to the genera of Mullidae, to the species occurring in the Red Sea, and to the two Mediterranean species of Mullus that have been reported from the Suez Canal. The distinction between the genera Pseudupeneus and Parupeneus is discussed. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1988
For you my God
- Marimba Group, Composer Not Specified, Dargie, Dave
- Authors: Marimba Group , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Music--Religious aspects , Field recordings , Africa, Sub-Saharan , Europe Germany Munich gw
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/317009 , vital:59890 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD140-24
- Description: Church song, accompanied by the Marimba and rattles.
- Full Text: false
- Date Issued: 1988
- Authors: Marimba Group , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Music--Religious aspects , Field recordings , Africa, Sub-Saharan , Europe Germany Munich gw
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/317009 , vital:59890 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD140-24
- Description: Church song, accompanied by the Marimba and rattles.
- Full Text: false
- Date Issued: 1988
Forever shining
- Church Choir, Composer Not Specified, Dargie, Dave
- Authors: Church Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309010 , vital:58986 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-50
- Description: Palm Sunday Mass hymn.
- Full Text: false
- Date Issued: 1988
- Authors: Church Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309010 , vital:58986 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-50
- Description: Palm Sunday Mass hymn.
- Full Text: false
- Date Issued: 1988
Geological control of aquifer properties of the Chuniespoort Group in the Klip River Valley and Natalspruit Basin, Transvaal
- Foster, Michael Benedict John
- Authors: Foster, Michael Benedict John
- Date: 1988 , 2013-03-08
- Subjects: Hydrogeology -- South Africa -- Transvaal , Aquifers -- South Africa -- Transvaal , Water supply -- South Africa -- Transvaal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4881 , http://hdl.handle.net/10962/d1013338
- Description: The aquifer of the study area occupies an escarpment and low lying limestone plain, and exhibits a Vaal River type karst. The four dolomitic formations present fall into two distinct aquifer forming types; chert poor units and chert rich units. The chert poor units of the Oaktree and Lyttelton Formations were deposited in a subtidal environment and were probably dolomi tised in a migrating schizohaline environment during basin subsidence and shoreline trangression. The chert rich units of the Monte Christo and Eccles Formations were deposited in the shallow subtidal to supratidal zones and the interbedded chert and dolomites may result from minor cyclical marine trangressions and regressions or be a geochemical response to the periodic flooding of freshwater carbonate and flats and tidal deltas. These fundamental geological differences are reflected in correspondingly different development of karst. Transmissive zones in the chert poor units are generally discrete solution features in massive dolomite, 1 m to 2 m thick. Transmissive zones in the chert rich units comprise thick (up to 60 m) and extremely weathered chert with a high void content resulting from the dissolution of carbonate material. The relative importance of various geological features to the development of the karst was assessed using information from two extensive hydrogeological investigations of the area. From the results it bas been concluded that lithostratigraphy, including the occurrence of palaeokarstic horizons, is the major control of aquifer properties. All other geological features are of lesser importance but may nevertheless be associated with enhanced transmissivi ties in any given unit. Faults and lineaments are the structural features most widely associated with highly transmissive zones. The knowledge gained in this study is applicable elsewhere as the principal hydrogeological characteristics of the study area are common to many of the Chuniespoort Group aquifers in the Pretoria - Witwatersrand - Vereeniging Region.
- Full Text:
- Date Issued: 1988
- Authors: Foster, Michael Benedict John
- Date: 1988 , 2013-03-08
- Subjects: Hydrogeology -- South Africa -- Transvaal , Aquifers -- South Africa -- Transvaal , Water supply -- South Africa -- Transvaal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4881 , http://hdl.handle.net/10962/d1013338
- Description: The aquifer of the study area occupies an escarpment and low lying limestone plain, and exhibits a Vaal River type karst. The four dolomitic formations present fall into two distinct aquifer forming types; chert poor units and chert rich units. The chert poor units of the Oaktree and Lyttelton Formations were deposited in a subtidal environment and were probably dolomi tised in a migrating schizohaline environment during basin subsidence and shoreline trangression. The chert rich units of the Monte Christo and Eccles Formations were deposited in the shallow subtidal to supratidal zones and the interbedded chert and dolomites may result from minor cyclical marine trangressions and regressions or be a geochemical response to the periodic flooding of freshwater carbonate and flats and tidal deltas. These fundamental geological differences are reflected in correspondingly different development of karst. Transmissive zones in the chert poor units are generally discrete solution features in massive dolomite, 1 m to 2 m thick. Transmissive zones in the chert rich units comprise thick (up to 60 m) and extremely weathered chert with a high void content resulting from the dissolution of carbonate material. The relative importance of various geological features to the development of the karst was assessed using information from two extensive hydrogeological investigations of the area. From the results it bas been concluded that lithostratigraphy, including the occurrence of palaeokarstic horizons, is the major control of aquifer properties. All other geological features are of lesser importance but may nevertheless be associated with enhanced transmissivi ties in any given unit. Faults and lineaments are the structural features most widely associated with highly transmissive zones. The knowledge gained in this study is applicable elsewhere as the principal hydrogeological characteristics of the study area are common to many of the Chuniespoort Group aquifers in the Pretoria - Witwatersrand - Vereeniging Region.
- Full Text:
- Date Issued: 1988
Gloria from the Missa Zimbabwe
- Ga-Rankuwa Marimba Group, Composer Not Specified, Dargie, Dave
- Authors: Ga-Rankuwa Marimba Group , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa South Africa Ga-Rankuwa f-sa
- Language: Latin , English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/310604 , vital:59168 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD120-21
- Description: Choral Church Music Festival Performance with Marimba accompaniment.
- Full Text: false
- Date Issued: 1988
- Authors: Ga-Rankuwa Marimba Group , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa South Africa Ga-Rankuwa f-sa
- Language: Latin , English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/310604 , vital:59168 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD120-21
- Description: Choral Church Music Festival Performance with Marimba accompaniment.
- Full Text: false
- Date Issued: 1988
History outside the classroom : the use of museums in the teaching of history
- Authors: Rheeder, Willem Lodewikus
- Date: 1988
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:21147 , http://hdl.handle.net/10962/6584
- Description: In the modern technical age in which we live , knowledge of the past is often pushed into the background As a result of this history teaching often becomes an attempt to pump an assortment of arbitrary facts into the minds of scholars by means of 'chalk and talk' methods. Educationists all over the world see this tendency as the major reason for the declining popularity of history as a school subject . In other parts of the world, such as the United States of America and Britain, education departments and teachers have faced this challenge and it seems as if the status of history as a school subject has been retrieved . In the Republic of South Africa the new core syllabuses are geared towards moving away from the earlier restricted emphasis of facts, but there is very little guidance on how teachers are to implement this 'new' approach, which focus more on the "how" of history and on the teaching of historical skills In this thesis museum visits as one of the modes of outdoor education, is studied as a possible additional alternative method of teaching history in South African schools . A study is made of what museums are and of the possible educational values of museum visits. It soon becomes clear that the major beneficial aspect of museum visits could be the acquisition of historical skills such as comprehension, application , analysis , synthesis and evaluation In order to gain insight into the practical implementation of museum visits several groups were observed while visiting the museum, after which two pilot studies were undertaken in the Kaffrarian and South African Missionary Museums with Black standard ten pupils and senior student teachers . Attention is given to aspects of administrative , teacher and pupil preparation the implementation of the visit and the types of follow-up work which could be used. During and after the implementation of the two pilot studies certain characteristic problems were experienced these are : the compilation of worksheets and cultural differences . The most important of language difficulties : It also became clear that education officers at museums find it difficult to cope with the special educational needs of the different visiting groups . For this reason an approach is advocated where the teacher compiles his own worksheet suited to the needs of his specific pupils Guidelines are given as to how pre-planned worksheets could be adapted : how different question-types could be used to compile a worksheet in which skills ascend from the simple to the complex: and how worksheets could be compiled for mixed ability groups. It is hoped that this thesis will lead to renewed interest in the use of the museum in the teaching of history and will serve as guideline for teachers planning to take history "out of its coffin".
- Full Text:
- Date Issued: 1988
- Authors: Rheeder, Willem Lodewikus
- Date: 1988
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:21147 , http://hdl.handle.net/10962/6584
- Description: In the modern technical age in which we live , knowledge of the past is often pushed into the background As a result of this history teaching often becomes an attempt to pump an assortment of arbitrary facts into the minds of scholars by means of 'chalk and talk' methods. Educationists all over the world see this tendency as the major reason for the declining popularity of history as a school subject . In other parts of the world, such as the United States of America and Britain, education departments and teachers have faced this challenge and it seems as if the status of history as a school subject has been retrieved . In the Republic of South Africa the new core syllabuses are geared towards moving away from the earlier restricted emphasis of facts, but there is very little guidance on how teachers are to implement this 'new' approach, which focus more on the "how" of history and on the teaching of historical skills In this thesis museum visits as one of the modes of outdoor education, is studied as a possible additional alternative method of teaching history in South African schools . A study is made of what museums are and of the possible educational values of museum visits. It soon becomes clear that the major beneficial aspect of museum visits could be the acquisition of historical skills such as comprehension, application , analysis , synthesis and evaluation In order to gain insight into the practical implementation of museum visits several groups were observed while visiting the museum, after which two pilot studies were undertaken in the Kaffrarian and South African Missionary Museums with Black standard ten pupils and senior student teachers . Attention is given to aspects of administrative , teacher and pupil preparation the implementation of the visit and the types of follow-up work which could be used. During and after the implementation of the two pilot studies certain characteristic problems were experienced these are : the compilation of worksheets and cultural differences . The most important of language difficulties : It also became clear that education officers at museums find it difficult to cope with the special educational needs of the different visiting groups . For this reason an approach is advocated where the teacher compiles his own worksheet suited to the needs of his specific pupils Guidelines are given as to how pre-planned worksheets could be adapted : how different question-types could be used to compile a worksheet in which skills ascend from the simple to the complex: and how worksheets could be compiled for mixed ability groups. It is hoped that this thesis will lead to renewed interest in the use of the museum in the teaching of history and will serve as guideline for teachers planning to take history "out of its coffin".
- Full Text:
- Date Issued: 1988
I have decided to follow Jesus
- Composition Workshop Choir, Peregrina, Sister, Dargie, Dave
- Authors: Composition Workshop Choir , Peregrina, Sister , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Katutura f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309535 , vital:59048 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD118-06
- Description: Practise session during composition workshop.
- Full Text: false
- Date Issued: 1988
- Authors: Composition Workshop Choir , Peregrina, Sister , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Katutura f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309535 , vital:59048 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD118-06
- Description: Practise session during composition workshop.
- Full Text: false
- Date Issued: 1988
If you think God is dead, take your time and look around
- Church Music Workshop Participants, Composer Not Specified, Dargie, Dave
- Authors: Church Music Workshop Participants , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Botswana Mahalapye f-bs
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/312764 , vital:59414 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD129-10
- Description: Practise and performance of church hymn, accompanied by the Marimba.
- Full Text: false
- Date Issued: 1988
- Authors: Church Music Workshop Participants , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Botswana Mahalapye f-bs
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/312764 , vital:59414 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD129-10
- Description: Practise and performance of church hymn, accompanied by the Marimba.
- Full Text: false
- Date Issued: 1988
Jesus
- St Paul's Choir, Composer Not Specified, Dargie, Dave
- Authors: St Paul's Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa South Africa Ga-Rankuwa f-sa
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/310321 , vital:59139 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD119-36
- Description: Music Festival Performance.
- Full Text: false
- Date Issued: 1988
- Authors: St Paul's Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa South Africa Ga-Rankuwa f-sa
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/310321 , vital:59139 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD119-36
- Description: Music Festival Performance.
- Full Text: false
- Date Issued: 1988
Jesus of Nazareth
- St Mary's Choir, Composer Not Specified, Dargie, Dave
- Authors: St Mary's Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309327 , vital:59024 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-78
- Description: Recording Session of Catholic Choirs.
- Full Text: false
- Date Issued: 1988
- Authors: St Mary's Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309327 , vital:59024 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-78
- Description: Recording Session of Catholic Choirs.
- Full Text: false
- Date Issued: 1988
John Chrysostom's understanding of the Eucharist in its relation to the Christian life
- Authors: Amos, Charles Harry
- Date: 1988
- Subjects: John Chrysostom, Saint, d. 407 , Lord's Supper , Lord's Supper -- Biblical teaching
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1217 , http://hdl.handle.net/10962/d1001547
- Description: The aim of this thesis is to reveal the intimate relationship between John Chrysostom's Eucharistic theology and the christian life, and that at the Eucharist Man's true being is demonstrated. It investigates Chrysostom's exegetical and oratorical method in order to ascertain how he approached a text and how he delivered his understanding of it. He is a representative of the Antiochene School of Exegesis and his fame as a preacher was a result not so much of his oratorical construction, but of the underlying spiritual unity within the oration. The purpose of all his preaching and exegesis was to evoke a moral response from his hearers. In the consecration of the elements, Chrysostcm displayed a remarkable openness to the varying traditions. He saw reciting the words of institution and invoking the Spirit as effecting consecration. Not only this, but also the moral life of the congregation played its part in effecting consecration. Once the elements had been consecrated, Christ was sacrificed, symbolically and literally, not again but in memory (Greek letters) of the Passion, which thereby becomes a present reality. In Chrysostom's understanding of the real presence he displays yet again an openness to the traditions. Christ is both present symbolically through the elements and literally through the transformation of the elements. The real presence demanded of the communicant a high degree of morality. To approach the Table on which Christ lay demanded a life of virtue, not only from the individual communicant but from the whole community. Those who partook unworthily imitated Judas and shared his fate. The community had to approach the Table in unity. At the Table, however, the community received its unity from Christ, the community became the body of Christ. Through participation and becoming the body of Christ, the community was united with the Godhead . Schism, therefore, was a very serious sin for it tore the body of Christ apart. For Chrysostom, Christ was also present in and intimately united with the poor. The church had to be able to be aware of Christ's presence in the poor and be responsible toward Him. In giving to the poor, the communiicant acknowledged that he/she had received at the Table and also received his/her salvation from Christ through the poor. The whole Eucharistic feast not only fed the christian with spiritual food, but called the communicant away from gross materialism to a life-giving dependance on God. It called the communicant to give to others as he/she had received from Christ.
- Full Text:
- Date Issued: 1988
- Authors: Amos, Charles Harry
- Date: 1988
- Subjects: John Chrysostom, Saint, d. 407 , Lord's Supper , Lord's Supper -- Biblical teaching
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1217 , http://hdl.handle.net/10962/d1001547
- Description: The aim of this thesis is to reveal the intimate relationship between John Chrysostom's Eucharistic theology and the christian life, and that at the Eucharist Man's true being is demonstrated. It investigates Chrysostom's exegetical and oratorical method in order to ascertain how he approached a text and how he delivered his understanding of it. He is a representative of the Antiochene School of Exegesis and his fame as a preacher was a result not so much of his oratorical construction, but of the underlying spiritual unity within the oration. The purpose of all his preaching and exegesis was to evoke a moral response from his hearers. In the consecration of the elements, Chrysostcm displayed a remarkable openness to the varying traditions. He saw reciting the words of institution and invoking the Spirit as effecting consecration. Not only this, but also the moral life of the congregation played its part in effecting consecration. Once the elements had been consecrated, Christ was sacrificed, symbolically and literally, not again but in memory (Greek letters) of the Passion, which thereby becomes a present reality. In Chrysostom's understanding of the real presence he displays yet again an openness to the traditions. Christ is both present symbolically through the elements and literally through the transformation of the elements. The real presence demanded of the communicant a high degree of morality. To approach the Table on which Christ lay demanded a life of virtue, not only from the individual communicant but from the whole community. Those who partook unworthily imitated Judas and shared his fate. The community had to approach the Table in unity. At the Table, however, the community received its unity from Christ, the community became the body of Christ. Through participation and becoming the body of Christ, the community was united with the Godhead . Schism, therefore, was a very serious sin for it tore the body of Christ apart. For Chrysostom, Christ was also present in and intimately united with the poor. The church had to be able to be aware of Christ's presence in the poor and be responsible toward Him. In giving to the poor, the communiicant acknowledged that he/she had received at the Table and also received his/her salvation from Christ through the poor. The whole Eucharistic feast not only fed the christian with spiritual food, but called the communicant away from gross materialism to a life-giving dependance on God. It called the communicant to give to others as he/she had received from Christ.
- Full Text:
- Date Issued: 1988
Kumbaya
- Church Choir, Composer Not Specified, Dargie, Dave
- Authors: Church Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309296 , vital:59021 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-76
- Description: Recording Session of Catholic Choirs.
- Full Text: false
- Date Issued: 1988
- Authors: Church Choir , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Gobabis f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/309296 , vital:59021 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-76
- Description: Recording Session of Catholic Choirs.
- Full Text: false
- Date Issued: 1988
Life history changes of two reef fish species in exploited and unexploited marine environments in South Africa
- Authors: Buxton, Colin David
- Date: 1988
- Subjects: Reef fishes -- Africa, Southern Chrysoblephus laticeps Chrysoblephus cristiceps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5189 , http://hdl.handle.net/10962/d1001965
- Description: A detailed investigation into the life histories of Chrysoblephus laticeps and c. cristiceps in exploited and unexploited marine environments on the south-east coast of southern Africa is presented. The study provided information necessary for the evaluation of marine reserves as a management option for these and similar reef species. Visual underwater assessments showed a clear spatial separation between adults and juveniles of both species, suggesting a recruitment of juveniles into shallow water followed by a gradual outward migration into deeper water with age. Denslty estlmates of C. laticeps in the Noordhoek (0.0064 fish/m²) and Tsitslkamma (0.0254 fish/m²) areas were significantly different and were attributed to exploitation. Within area differences in density were also significantly correlated with temperature) depth and substratum relief. Similar comparisons for C. cristiceps were not possible because these fish shied away from divers. Habitat preferences were mirrored in the diets of both species which fed on a wide variety of reef associated benthic animals. Size of prey appeared to be gape limited, only larger fish being able to manipulate prey. Quantitative differences between the diets of fish sampled in different areas were a reflection of differences in available prey and not related to the relative density of predators. The dietary characteristics recorded in these fish were typical of search hunters. An age and growth study based on the examination of sectioned otoliths showed that both species were slow growing and long lived. Maximum recorded ages were 18 and 22 years for C. laticeps and C. cristiceps respectively. Growth rates in exploited and unexploited areas were not significantly different although there was an indication that growth was slower in the exploited areas for C. cristiceps. Several inconsistencies in otolith interpretation and terminology were evaluated. Contrary to other South African studies the results suggested that somatic growth was fastest just after spawning. This coincided with the winter months and was reflected by the deposition of a hyaline zone in the otolith. Two independent estimates, the Pauli derivation and visually assessed length frequency analysis, produced the same value for total mortality of C. laticeps in the Tsitsikamma area (0.2). This result, together with a significant difference in the rate of fishing mortality at different areas along the coast suggested that the populations sampled were discrete and supported the postulate that both species were sedentary. Further support was obtained from a mark-recapture study. Although sample numbers were low the results showed no evidence of large scale migratory patterns in these fish. An investigation of the reproductive biology of both fish showed that they were protogynous hermaphrodites, all males being derived from females with no evidence for polyandry. Males were shown to be capable of mating with a number of females and this, together with monandry, monochromatism and a small testis size, suggested a polygynous mating system in both species. Observations of the courtship behaviour in captive c. laticeps also supported polygyny. A significant difference in the mean size at sex reversal between unexploited and exploited populations supported the postulate that sex reversal was independent of the size or age of the animal. The size at which sex reversal occurred appeared to be dependent on sex ratio. A detailed yield per recruit analysis of the response of the population to different levels of fishing mortality and size at recruitment (t [subscript]r), showed that sex reversing species were particularly vulnerable to over fishing. This was due to a dramatic decline in the number of surviving individuals past t[subscript]r which resulted in a skewing of the sex ratio towards females. Evidence is presented to show that current legislation is inadequately protecting the spawner stock of both species. In conclusion it is shown that longevity, sex reversal, restricted movements and the occupation of a demersal habitat make these species particularly vulnerable to over exploitation in a size- selective fishery. The sustained yield in the linefishery is suggested to be a result of distant recruitment from relatively unexploited populations rather than the adequacy of current conservation measures. The need to protect the spawner stock is emphasised and the use of marine reserves as an additional protection for sedentary reef-dwelling species is therefore advocated.
- Full Text:
- Date Issued: 1988
- Authors: Buxton, Colin David
- Date: 1988
- Subjects: Reef fishes -- Africa, Southern Chrysoblephus laticeps Chrysoblephus cristiceps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5189 , http://hdl.handle.net/10962/d1001965
- Description: A detailed investigation into the life histories of Chrysoblephus laticeps and c. cristiceps in exploited and unexploited marine environments on the south-east coast of southern Africa is presented. The study provided information necessary for the evaluation of marine reserves as a management option for these and similar reef species. Visual underwater assessments showed a clear spatial separation between adults and juveniles of both species, suggesting a recruitment of juveniles into shallow water followed by a gradual outward migration into deeper water with age. Denslty estlmates of C. laticeps in the Noordhoek (0.0064 fish/m²) and Tsitslkamma (0.0254 fish/m²) areas were significantly different and were attributed to exploitation. Within area differences in density were also significantly correlated with temperature) depth and substratum relief. Similar comparisons for C. cristiceps were not possible because these fish shied away from divers. Habitat preferences were mirrored in the diets of both species which fed on a wide variety of reef associated benthic animals. Size of prey appeared to be gape limited, only larger fish being able to manipulate prey. Quantitative differences between the diets of fish sampled in different areas were a reflection of differences in available prey and not related to the relative density of predators. The dietary characteristics recorded in these fish were typical of search hunters. An age and growth study based on the examination of sectioned otoliths showed that both species were slow growing and long lived. Maximum recorded ages were 18 and 22 years for C. laticeps and C. cristiceps respectively. Growth rates in exploited and unexploited areas were not significantly different although there was an indication that growth was slower in the exploited areas for C. cristiceps. Several inconsistencies in otolith interpretation and terminology were evaluated. Contrary to other South African studies the results suggested that somatic growth was fastest just after spawning. This coincided with the winter months and was reflected by the deposition of a hyaline zone in the otolith. Two independent estimates, the Pauli derivation and visually assessed length frequency analysis, produced the same value for total mortality of C. laticeps in the Tsitsikamma area (0.2). This result, together with a significant difference in the rate of fishing mortality at different areas along the coast suggested that the populations sampled were discrete and supported the postulate that both species were sedentary. Further support was obtained from a mark-recapture study. Although sample numbers were low the results showed no evidence of large scale migratory patterns in these fish. An investigation of the reproductive biology of both fish showed that they were protogynous hermaphrodites, all males being derived from females with no evidence for polyandry. Males were shown to be capable of mating with a number of females and this, together with monandry, monochromatism and a small testis size, suggested a polygynous mating system in both species. Observations of the courtship behaviour in captive c. laticeps also supported polygyny. A significant difference in the mean size at sex reversal between unexploited and exploited populations supported the postulate that sex reversal was independent of the size or age of the animal. The size at which sex reversal occurred appeared to be dependent on sex ratio. A detailed yield per recruit analysis of the response of the population to different levels of fishing mortality and size at recruitment (t [subscript]r), showed that sex reversing species were particularly vulnerable to over fishing. This was due to a dramatic decline in the number of surviving individuals past t[subscript]r which resulted in a skewing of the sex ratio towards females. Evidence is presented to show that current legislation is inadequately protecting the spawner stock of both species. In conclusion it is shown that longevity, sex reversal, restricted movements and the occupation of a demersal habitat make these species particularly vulnerable to over exploitation in a size- selective fishery. The sustained yield in the linefishery is suggested to be a result of distant recruitment from relatively unexploited populations rather than the adequacy of current conservation measures. The need to protect the spawner stock is emphasised and the use of marine reserves as an additional protection for sedentary reef-dwelling species is therefore advocated.
- Full Text:
- Date Issued: 1988
Light of God
- Doringveld Congregation, Composer Not Specified, Dargie, Dave
- Authors: Doringveld Congregation , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Doringveld f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/308927 , vital:58974 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-40
- Description: After Mass - Children singing religious song.
- Full Text: false
- Date Issued: 1988
- Authors: Doringveld Congregation , Composer Not Specified , Dargie, Dave
- Date: 1988
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Namibia Doringveld f-sx
- Language: English
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/308927 , vital:58974 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD117-40
- Description: After Mass - Children singing religious song.
- Full Text: false
- Date Issued: 1988