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Studies on captive rearing of spotted grunter, pommadasys commersonnii (Pisces : Haemulidae) under ambient conditions

  • Authors: Bacela, Ntobeko
  • Date: 1999
  • Subjects: Grunts (Fishes)
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5322 , http://hdl.handle.net/10962/d1005167 , Grunts (Fishes)
  • Description: The effects of stocking density, size grading, feeding frequency and ambient temperature on the growth performance and size variation of spotted grunter, Pomadasys commersonnii were investigated. The time that would be required to rear the species to market size was modelled. An area where maximum growth rate could be achieved under ambient temperature conditions, and therefore the location of a commercial farm within the distribution range of spotted grunter along the coast of South Africa, was predicted. The growth performance of spotted grunter was not significantly affected by stocking density. Growth performance seemed to improve with increasing stocking density. Competitive behaviour was absent among fish in the various stocking densities. Growth in terms of fork length and body weight was not significantly different between stocking densities. The highest specific growth rate, best food consumption, food conversion ratio and protein efficiency ratio of the fish were recorded at a density of 6.4 kg/m³, whereas the best condition factor was recorded at a density of 3.8 kg/m³. The lack of significant difference in many of the growth parameters between the various stocking densities suggest that juvenile spotted grunter could be reared at densities higher than 6.4 kg/m³. Further investigations are needed to determine the optimal initial stocking density of juvenile spotted grunter under ambient temperature and photoperiod conditions. Replacing the largest fish with average sized fish did not have a significant effect on the specific growth rate and competitive behaviour based on the relationship between the coefficient of variation and average size. Feeding frequency had a sIgnificant effect on food consumption, food conversion and protein efficiency ratio, and not on size increase, specific growth rate and condition factor. Its effect on competitive behaviour could not be conclusively explained. The best food conversion ratio recorded when feeding once a day showed that although the fish consumed a limited amount of food, they utilised the food that was fed most effectively. It is suggested that the fish be fed three times a day. The survival of juvenile spotted grunter was 95.6 % when feeding three times a day compared to 90 and 90.2 % when feeding once and five times a day, respectively. Fluctuating ambient temperature had a dramatic effect on specific growth rate and food consumption of spotted grunter. Growth modelling showed that the fish could be reared to a market size of 550 g (270 mm FL) in 19 months under ambient temperature conditions (23.2°C) at Richard's Bay. The optimal predicted rearing period of 19 months is approximately seven months less than that calculated for fish in the wild, and can possibly, be reduced further by feeding a balanced diet. The overall food consumption (on a dry weight basis) in the three size classes ranged from 0.15 ± 0.16 to 0.38 ± 0.35 % body weight per day. Food conversion ratio improved with increasing fish size. This relationship was attributed to diet quality and more specifically, the protein : energy ratio. As a result, fish in the large size class had the best overall protein efficiency ratio. Maximum specific growth rates of1.5, 0.84 and 0.74 % body weight per day were recorded from the small, medium and large size classes in the peak of summer with average daily temperature ranging from 21 to 22°C. Positive slopes in the coefficient of variation against fish size in the large size class indicated the presence of competitive behaviour which was attributed to the onset of adolescence. The information from this study can be used for pilot production of spotted grunter. Further research should be undertaken to investigate captive reproduction of the species.
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  • Date Issued: 1999

Study of milk marketing by selected dairy companies in Port Elizabeth

  • Authors: Smith, Natalie Heather
  • Date: 1999
  • Subjects: Milk trade , Dairying -- South Africa -- Port Elizabeth , Dairying -- Management
  • Language: English
  • Type: Thesis , Masters , MTech (Management)
  • Identifier: vital:10827 , http://hdl.handle.net/10948/17 , Milk trade , Dairying -- South Africa -- Port Elizabeth , Dairying -- Management
  • Description: This paper concerns itself with decreasing milk consumption in the Port Elizabeth area and how the marketing mix influences marketing decisions. Personal interviews were conducted in different supermarkets to investigate consumer perceptions of milk, the brand purchased and how consumers use milk. The study indicated that people purchasing milk were very price conscious. Respondents showed almost no brand loyalty. However, respondents indicated that they were aware of the health benefits of drinking milk, although most used milk predominantly to whiten their tea and/or coffee. A comparison of the findings of this study to those of Geils (1981) and Hanekom (1990) indicates that the milk industry has the same problems in 1999 as it did in 1990 and in 1981. Findings reflect the unhealthy perception people have about milk. Many regard it as a child’s drink and others perceive it as fattening. Decreasing consumption figures indicate that there has been little effort or success from the dairy industry to change consumer perceptions of milk. Figures indicate that consumption of milk may be close to zero in 2015, if marketers of dairy companies do not improve the image of milk. However, a considerable amount of investment by overseas companies in Port Elizabeth dairies may increase marketing activities in the future. This paper begins with an overview of the major competitors in the Port Elizabeth area, highlighting their strengths and weaknesses. The importance of selecting the appropriate market mix for milk is discussed by explaining each mix element, namely, product, distribution, promotion and price. Distribution involves the delivery of the perishable product to outlets in the shortest space of time after production. Careful and efficient planning of refrigerated warehousing, transport and delivery services all indirectly contribute to the freshness and quality of milk. Promotion is one of the most important elements that can be used to change consumer perceptions of milk. It is necessary to select the correct message for the specific target group when advertising. Product benefits like milk’s purity, or naturalness, should be focused on rather than its creaminess and richness. Price constitutes the fourth element of the marketing mix. Price in the narrowest sense, is the amount of money charged for milk. The milk industry is intensely price sensitive which often results in price wars among competitors. Most consumers purchase the cheapest brand of milk indicating little brand loyalty, especially among top-end consumers.
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  • Date Issued: 1999

Sulphate reduction utilizing hydrolysis of complex carbon sources

  • Authors: Molipane, Ntaoleng Patricia
  • Date: 1999
  • Subjects: Sewage sludge , Acid mine drainage , Hydrolysis
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4000 , http://hdl.handle.net/10962/d1004060 , Sewage sludge , Acid mine drainage , Hydrolysis
  • Description: Due to environmental pollution caused by acid mine drainage (AMD), the Department of Water Affairs has developed a National Water Bill for managing and controlling the water environment to prevent AMD pollution. The application of sulphate reducing bacteria have been demonstrated for the treatment of AMD. However, the scale-up application of this technology ultimately depends on the cost and availability of a carbon source. This study evaluated the use of sewage sludge to provide a carbon source for sulphate reduction in synthetic drainage wastewaters. The demonstration of this process in a laboratory-scale reactor proved that sewage sludge could provide a useful model and viable carbon source for evaluation of sulphate reduction as a process for treating AMD. Since sewage sludge is a complex carbon source, hydrolysis reactions controlling the anaerobic digestion of particulate substrate from this medium were optimized by evaluating the effect of pH on hydrolysis. Controlled and uncontrolled pH studies were conducted using a three stage mixed anaerobic reactor. Analysis of the degradation behaviour of the three important organic classes (carbohydrate, proteins and lipids) revealed that each class followed an indvidual trend with respect to pH changes. In addition, the solubilization of organic particulate carbon was also shown to be a function of pH. The hydrolysis pattern of organic substrate and COD solublization was induced at pH 6.5 rather than at high pH values (7.5 and 8.5). The biodegradation activity of sewage sludge was characterized by the API-ZYM1N test system to provide rapid semiquantitative information on the activity of hydrolytic enzymes associated with the degradation of carbohydrates, lipids, proteins and nucleic acids. A wide range of enzyme activities with phosphatases, aminopeptidases, and glucosyl hydralases dominating were displayed. The pattern of substrate hydrolysis correlated to the degradation efficiency of each organic class as a function of pH. The evaluation of scale-up application for sulphate reduction utilizing sewage sludge as a carbon source demonstrated that large water volume flows could possibly be treated with this cost-effective technology. Generation of alkalinity and sulphide in this medium was shown to be successful in the removal of heavy metals by precipitation. The use of this technology coupled to reduced cost involved showed that biological sulphate reduction utilizing hydrolysates of complex organic particulate from sewage sludge ss a carbon source has a potential scale-up application for the treatment of AMD.
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  • Date Issued: 1999

Sylvester Mazinyane interview

  • Authors: Struan Douglas interviews Sylvester Mazinyane , International Library of African Music
  • Date: 1999
  • Subjects: Interviews , Africa South Africa Grahamstown f-sa
  • Language: English
  • Type: sound recordings , field recordings , sound recording-musical
  • Identifier: http://hdl.handle.net/10962/131556 , vital:36595 , International Library of African Music, Rhodes University, Grahamstown, South Africa , SDC54-01
  • Description: Sylvester Mzinyane recounts his musical inspirations including: Gospel music and hymns from church; American and South African jazz heard from township yards; popular music from the radio; his own imagination and spiritual experience; sounds he hears from the environment; playing with current South African jazz bands; studies at technical school and UCT College of Music; talking to other musicians from Africa and elswhere
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  • Date Issued: 1999

Sylvester Mazinyane interview continued

  • Authors: Struan Douglas interviews Sylvester Mazinyane , International Library of African Music
  • Date: 1999
  • Subjects: Interviews , Africa South Africa Grahamstown f-sa
  • Language: English
  • Type: sound recordings , field recordings , sound recording-musical
  • Identifier: http://hdl.handle.net/10962/131537 , vital:36593 , International Library of African Music, Rhodes University, Grahamstown, South Africa , SDC54-02
  • Description: Sylvester Mzinyane recounts his musical inspirations including: Gospel music and hymns from church; American and South African jazz heard from township yards; popular music from the radio; his own imagination and spiritual experience; sounds he hears from the environment; playing with current South African jazz bands; studies at technical school and UCT College of Music; talking to other musicians from Africa and elswhere
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  • Date Issued: 1999

Sylvester Mazinyane interview continued

  • Authors: Struan Douglas interviews Sylvester Mazinyane , International Library of African Music
  • Date: 1999
  • Subjects: Interviews , Africa South Africa Grahamstown f-sa
  • Language: English
  • Type: sound recordings , field recordings , sound recording-musical
  • Identifier: http://hdl.handle.net/10962/131532 , vital:36592 , International Library of African Music, Rhodes University, Grahamstown, South Africa , SDC54-02
  • Description: Sylvester Mzinyane recounts his musical inspirations including: Gospel music and hymns from church; American and South African jazz heard from township yards; popular music from the radio; his own imagination and spiritual experience; sounds he hears from the environment; playing with current South African jazz bands; studies at technical school and UCT College of Music; talking to other musicians from Africa and elswhere
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  • Date Issued: 1999

Systematic status of Plectroctena mandibularis Smith and P. conjugata Santschi (Hymenoptera: Formicidae: Ponerini)

  • Authors: Villet, Martin H , McKitterick, L , Robertson, Hamish G
  • Date: 1999
  • Language: English
  • Type: text , Article
  • Identifier: vital:6893 , http://hdl.handle.net/10962/d1011653
  • Description: Plectroctena mandibularis Smith is the type species of Plectroctena F. Smith. Because there has been some doubt about its distinctness from P. conjugata, several techniques were used to assess the systematic status of the two species. Most crucially, several colony series contained workers of both phenotypes, and where these series included queens or males, the distinguishing feature of these specimens was not consistently related to those of the workers. Queens, males and workers did not manifest qualitative differences between the taxa, and morphological variation was continuous between the two. The putative morphological basis (funicular index) for distinguishing workers of the taxa arose from allometric variation. Putatively diagnostic colour variation in males was related to latitude, but no simple pattern of morphological variation could be correlated with geographical distribution. Plectroctena conjugata is therefore considered a junior synonym of P. mandibularis.
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  • Date Issued: 1999

Tackling mild head injury in rugby: a comparison of the cognitive profiles of professional rugby and cricket players

  • Authors: Reid, Iain Robert
  • Date: 1999
  • Subjects: Head -- Wounds and injuries -- Complications , Rugby football injuries , Neuropsychological tests , Cricket -- Accidents
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3043 , http://hdl.handle.net/10962/d1002552 , Head -- Wounds and injuries -- Complications , Rugby football injuries , Neuropsychological tests , Cricket -- Accidents
  • Description: The aim of this study was to investigate the effect of cumulative mild head injury on the cognitive functioning of professional rugby players. A comprehensive battery of neuropsychological tests was administered to 26 professional rugby players and to a comparison group of 21 professional cricket players. The group test results of the rugby, cricket, rugby forwards and rugby backline players were each compared with established normative data. Generally, the comparison of the rugby and cricket mean scores relative to the normative data did not reveal significant differences on tests known to be sensitive to the effects of mild head injury. However, the comparison of variability for each of the rugby and cricket playing groups relative to variability for the normative data, revealed a pattern of increased variability among the rugby players. This implies a bimodal distribution in which a significant number of rugby players were performing poorly across these tests whereas a significant proportion were not. This variability effect was accounted for by further mean score comparisons which revealed that, as a group, it was the forward players whose performances were disproportionately poor on tests sensitive to the effects of mild head injury. The implications of these results are developed theoretically within the context of brain reserve capacity theory and suggestions for future research are provided.
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  • Date Issued: 1999

Tamayi

Tchiwara

Temporal variability in the effects of grazing by the territorial limpet Patella longicosta on the productivity of the crustose alga Ralfsia verrucosa

  • Authors: Kaehler, Sven , Froneman, P William
  • Date: 1999
  • Language: English
  • Type: Article
  • Identifier: vital:6935 , http://hdl.handle.net/10962/d1011956
  • Description: This study reports the effects of grazing by the territorial limpet Patella longicosta on the productivity of the encrusting alga Ralfsia verrucosa. Grazing significantly increased algal growth during the first month of the study (August). Simulated grazing by brushing also enhanced productivity. However, the productivity of grazed and ungrazed algae did not differ significantly during the ensuing three months. As the growth of ungrazed plants remained the same throughout the study, the elevated productivity of grazed plants during August was attributed to increased limpet activity. The variation in grazer-induced algal growth was possibly associated with increased feeding when the limpets embark on energetically costly periods of reproduction.
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  • Date Issued: 1999

Testing chemical markers on granivorous birds

  • Authors: Steele, G R , Whittington-Jones, Craig A , Craig, Adrian J F K
  • Date: 1999
  • Language: English
  • Type: Article
  • Identifier: vital:6936 , http://hdl.handle.net/10962/d1011957
  • Description: We tested two substances (oxytetracycline and rhodamine B) that can be added to food or water of free-living birds, and serve as markers in their plumage for later identification. Oxytetracycline produced no detectable changes in the plumage of red bishops or redbilled queleas. Rhodamine B fed to captive birds produced fluorescence in the wing feathers when viewed under ultraviolet light. This fluorescence lasted for at least 14 weeks, and was retained until feathers were moulted. Rhodamine B may thus be useful in identifying birds using a specific feeding site, and for studies of moult and feather growth.
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  • Date Issued: 1999

The 2326 MHZ radio continuum emission of the milky way

  • Authors: Jonas, Justin Leonard
  • Date: 1999
  • Subjects: Radio astronomy Southern sky (Astronomy) Milky Way
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5450 , http://hdl.handle.net/10962/d1005235
  • Description: The Rhodes/HartRAO SKYMAP survey is the highest frequency (2326 MHz) and highest resolution (20 arcmin) large-area pencil-beam survey of the celestial radio continuum emission. The survey covers 67 % of the entire sky and is one of only two radio continuum surveys that cover the southern sky. These attributes make the survey eminently suitable for studying the extended radio continuum emission from the Milky Way. This thesis describes the methodology used to produce the SKYMAP survey map and presents an analysis of the galactic radio continuum emission. Mountfort (1989, PhD thesis, Rhodes University) designed and implemented the original SKYMAP observing and data reduction procedures. These original procedures have been modified and extended to accommodate instrumentation upgrades at HartRAO and take advantage of new computer technologies that have become available. A new procedure was developed to perform the merging of the ten individual target-area maps into a self-consistent combined map without discontinuities at the component map boundaries. Calibration and data quality procedures were devised and implemented in order to validate the temperature scale and pointing accuracy of the map data. The uncertainty in the relative full-beam temperature scale is estimated to be 2 % and the RMS pixel noise is less than 30 mK. The uncertainty in the zero-level of the survey map is conservatively estimated to be 80 mK. The RMS pointing accuracy is better than 1.9 arcmin. The diffuse galactic background (DGB) emission is shown to be consistent with four-arm spiral models for the Milky Way. The Gould Belt system and the galactic warp beyond the solar-circle are seen as non-symmetrical distortions in the DGB. An empirical model of the DGB was subtracted from the 2326 MHz map data in order to accentuate faint, extended radio sources. A new technique was devised to discriminate between thermal and non-thermal radio continuum emission on the basis of FIR/radio flux ratios. This procedure was used to reduce the source confusion near the galactic plane. 42 new shell-like radio sources with angular diameters ranging from 1.6 deg to 26 deg are identified in the SKYMAP 2326 MHz map. These sources are probably large-diameter supernova remnants (SNRs) that partially redress the incompleteness in existing SNR catalogues caused by limited surface brightness selection effects. The shells of some of these faint, extended sources are incomplete towards high-latitudes. This morphology suggests that these objects are breaking out of the galactic disk and are releasing hot gas into the halo. There is no evidence for linear worm- and chimney-like features in the non-thermal galactic emission. The spectral index of the diffuse galactic emission is calculated to be beta = 2.72 +/- 0.18 between 408 MHz and 2326 MHz and beta = 2.95 +/- 0.08 between 2326 MHz and 31 GHz, confirming previous work showing that the synchrotron spectrum steepens with increasing frequency. The high frequency spectral index is used to estimate upper limits on the galactic synchrotron foreground contamination of cosmic microwave background radiation measurements. The high-latitude 2326 MHz galactic emission is shown to correlate weakly with the far-infrared galactic cirrus clouds. This correlation is due to thermal free-free radio emission from extended, low-density HII regions associated with the cirrus dust. The RMS level of this thermal signal is estimated to be 1 mK at 2326 MHz. Two further experiments that need to be performed in order to complete the SKYMAP project are discussed: (a) the region of sky near the southern equatorial pole (SEP) needs to be mapped at HartRAO to complete the coverage of the entire southern sky, and (b) independent horn telescope (broad-beam) measurements of the sky temperature are required in order to reduce the baseline uncertainties in the current SKYMAP data.
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  • Date Issued: 1999

The cicada genus Nyara n. gen. (Homoptera Cicadidae) systematics, behaviour and conservation status

  • Authors: Villet, Martin H
  • Date: 1999
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/453870 , vital:75295 , https://doi.org/10.1080/03946975.1999.10539385
  • Description: The cicada genus Nyara n. gen. and its sole species N. thanatotica n. sp. are described and diagnosed. This species is very peculiar because it often feigns death when disturbed. This is the first time such behaviour has been described in a cicada. Nyara is the third endemic cicada genus described from a South African forest. Its distribution along the subtropical Eastern Cape coast, which is threatened by strip mining and housing developments, highlights the need for conservation of these under-researched habitats.
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  • Date Issued: 1999

The classification of negative polarity items evidence from Dutch and Afrikaans

  • Authors: Ter Horst, Paulus Willem
  • Date: 1999
  • Subjects: Polarity , Grammar, Comparative and general -- Negatives , Semantics
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2364 , http://hdl.handle.net/10962/d1002647 , Polarity , Grammar, Comparative and general -- Negatives , Semantics
  • Description: In this thesis I discuss the problem of negative polarity items (NPls). NPis are items that have to be licensed by a certain group of expressions. In this group of expressions which can trigger NPIs we find, among other things: negations, adversative expressions, questions and conditionals. I show that there is an important problem for a grammatical approach to negative polarity: the group of expressions which can licence NPls can't be adequately defined in a grammatical way. There is, however, a semantic way of defining the group of expressions that can licence NPIs. In semantics the group is often referred to as the group of "triggers". It can be proven logically that the group of triggers can be divided into four subgroups: a group of downward-entailing expressions, antimultiplicative expressions, anti-additive expressions and antimorphic expressions. By carrying out a corpus study I find evidence for the hypothesis that the way in which NPIs are licenced by the triggers with different logical properties originates from the different grammatical classes of NPIs (negative polarity nouns, negative polarity adjectives and negative polarity verbs). Since there is evidence for this causal relation, I argue that a grammatical approach to NPI-triggering is necessary from a formal point of view. I give a Minimalist account of NPI-triggering. To make the Minimalist Program suitable for NPI-triggering I have to assume, however, that the semantic information about triggers is available in the lexicon of the MP.
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  • Date Issued: 1999

The coastal grasslands of the Eastern Cape west of the Kei River

  • Authors: Judd, Rachel Anne
  • Date: 1999
  • Subjects: Grassland ecology -- South Africa -- Eastern Cape Grasslands -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4203 , http://hdl.handle.net/10962/d1003772
  • Description: The grasslands of South Africa are the foundation of commercial and subsistence agriculture yet they are being degraded at an alanning rate. The coastal grasslands of the Eastern Cape are no exception and they suffer added pressure of coastal resort development because of their proximity to an attractive coastline. In order to determine the degree of conservation necessary for any area it is essential to know what species occur there in order to determine if protection from habitat destruction is required. Four aims were defined for this studv. The initial aim was a phytogeographical classification of the grasslands in the coastal region west of the Kei River. This was done by vegetation sampling followed by computer based analysis with TWINSPAN. This analysis defined ten grassland associations. five being located in the area west of the Keiskamma River and five occurring east of it. The associations in the eastern half are termed mesic while those in the western balf are xeric. The second aim was to determine the presence of any underlying ecological gradients affecting the distribution of tbe associations. Indirect gradient analysis was carried out where samples are analysed irrespective of environmental factors. Direct gradient analysis was then carried out using scores per sample of various environmental factors. Environmental factors whicb migbt produce such gradients are both naturally-ocurring and man-induced. Natural factors which were recorded in the field include depth of soil at sample site, soil family, aspect and distance from the shore. An important factor is the land / sea interface. Natural factors analysed in the laboratory include soil pH. conductivity. percent organic matter, calcium, magnesium, phosphate and potassium. Man-induced factors are land use history e.g. Ploughing and grazing. Both direct and indirect gradient analysis were carried out with the computer based programme CANOCO. The third aim of the study was to determine the presence of any successional trends between the ten defined associations. This was done using several characteristics of the associations. Alpha and beta diversity were the first factors compared between associations. The percentage contribution of the Cyperaceae, Fabaceae, Asteraceae and Poaceae to each association was assessed and compared. The presence of various life forms of the species occurring in each association was determined together with the cover abundance of different classes of grass species. These results were then combined and analysed in the light of the results from CANOCO analvsis. They show that the mesic Themeda Iriandra - Anthospermum herhoceum, association which occurs closest to the shore and with the least disturbance is a depauperate form of the mesic climax Themeda triandra association. The mesic Hyparrhenia hirta - Dtheteropogon amplectens association may be a secondary grassland on account of phosphate and potassiun poor soils and land-use. The mesic Hyparrhenia hirta - Themedo triandra association is a slightly degraded form of the climax association due to grazing. The severely disturbed Stenotaphrum secundatum - C'entella coriacea association, which is located close to the shore, is a secondary grassland. Analysis of the xeric associations indicates a clearly defined ordination of associations on the basis of land-use. The Cynodon daclylon - Helictolrichon hirtulum and Sporobolis africanus - Setaria sphacelata associations which occur where ploughed lands have been left to lie fallow are secondary in nature. The Themeda triandra - Ehrharta calycina association is thought to be the closest representati ve of a climax xeric association but the presence of E. calycina indicates that some disturbance has occurred. The vegetation is subject to moderate grazing. The Cynodon dactylon - Ehrharla calycina and Diheleropogon filifolius - Ehrharla calycina associations are subject to varying intensities of trampling and grazing and are degraded forms of the Themeda triandra - Ehrharla calycina association. Because of tbe overriding influence of the land-use gradient separation along gradients of the remaining eight factors was limited. The effect of fire and temporal change in the mesic Themeda triandra and Hyparrhenia hirta - Themeeia trianda associations was assessed via long-term studies at Potter's Pass outside East London. The results show a quick response to burning with a return to 100% cover within six months by both associations. During spring the two associations could not be separated by either TWINSPAN or DECORANA. indicating a temporal shift from the Hyparrhenia hirta - Themeda triandra association to the Themeda triandra association. The fourth and final aim was to identify plants requiring protection from habitat destruction and to make recommendations for further conservation areas and management of the coastal grasslands. Through the collection and identification of as many plants as possible a species checklist was prepared and the status of each was determined through reference to the Red Data Book of threatened and endangered species. Kniphofia rooperi is vulnerable in the Cape and Euphorbia hupleuroides is considered rare in kwazulu-Natal. Ten species are endemic to the Cape and / or South Africa. The richness of the vegetation lies in the presence of species representative of the four major floras which converge in the eastern Cape. i.e. The Cape, NamaKarroo, Tongoland-Pondolaod floras and the Kalahari Highveld Regional Transitional Zone. Suggestions are made for the conservation of the grassland associations at various sites within the study area based on the present area conserved. Less than 2% of the coastline in the study area is conserved and it is felt that the area under conservation should be increased. Management suggestions based on the available literature are given for both farmed and conserved areas. There is a great potential for further studies on grassland dmamics within the areas surveyed. In terms of management, the grasslands require careful examination to determine the most effective season in which to burn if at all. As with most agricultural systems in South Africa. grazing strategies will benefit from further research. Any additional research on the dynamics of these grasslands can only be of benefit to the sustained utilisation of this vital resource.
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  • Date Issued: 1999

The development from a Wesleyan perspective of an appropriate model of multi-cultural ministry, from within a traditionally mono-cultural Methodist congregation

  • Authors: Rist, Timothy John
  • Date: 1999
  • Subjects: Wesley, John, 1703-1791 , Religion and culture , Methodist church buildings -- South Africa , Methodist church buildings -- South Africa -- Bloemfontein
  • Language: English
  • Type: Thesis , Masters , MTh
  • Identifier: vital:1309 , http://hdl.handle.net/10962/d1018218
  • Description: From introduction: The intention of this thesis is to develop a model for multi-cultural ministry, and, in so doing, to enable Trinity Methodist Church, Charles Street, Bloemfontein to provide a comprehensive and meaningful ministry to all people, one that is not limited by the constraints of language and culture but which transcends them. The fact that Trinity is a Methodist Church means that I will be establishing the "Model for Multi-Cultural Ministry" firmly within Wesleyan theology. South Africa has undergone far-reaching political change since the general elections of April 1994. This political transformation has emphasised a need for the bringing together of people across the barriers of race, culture and religion. In this thesis I will be focusing my attention on the latter - the realm of religion - and specifically that of Christianity. Furthermore, I will be restricting my attention to a specific congregation within the denomination of Methodism, within the religion of Christianity, namely Trinity Methodist Church, Charles Street, Bloemfontein'. The "Model for MultiCultural Ministry" developed in this thesis will therefore be 'congregation specific'. The Methodist ChurcQ of Southern Africa2 proclaims itself to be a Church "one and undivided" (Minutes: 1980: 65: para l(a) ), where people from all racial groups can worship God together in a meaningful way. In many respects this is not the case. The years of political pressure that the (MCSA) has endured, in particular the years of legislated Apartheid (1948-1989), ensured that existing divisions between the Methodist congregations became entrenched along racial, cultural and religious lines (Thompson: 1990: 187ff). The Group Areas Act (1950) is but one such example where the National Party Government "divided urban areas into zones where members of one specified race alone could live and work" (Thompson: 1990: 194). The homeland policy (implemented from 1963, but legislated from 1971 in the Bantu Homelands Constitution Act).
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  • Date Issued: 1999

The Development of a Generic Framework for the Implementation of Cheap, Component-Based Virtual Video-Conferencing System

  • Authors: Panagou, Soteri , Bangay, Shaun D
  • Date: 1999
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/432824 , vital:72903 , https://www.cs.ru.ac.za/research/Groups/vrsig/pastprojects/014humanmodelling/paper03.pdf
  • Description: We address the problem of virtual-videoconferencing. The proposed solution is effected in terms of a generic framework based on an in-house Virtual Reality system. The framework is composed of a number of distinct components: model acquisition, head tracking, expression analysis, network transmission and avatar reconstruction. The framework promises to provide a unique, cheap, and fast system for avatar construction, transmission and animation. This approach affords a conversion from the traditional video stream approach to the management of an avatar remotely and consequently makes minimal demands on network resources.
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  • Date Issued: 1999

The development of an immobilised-enzyme bioprobe for the detection of phenolic pollutants in water

  • Authors: Russell, Ingrid Margaret
  • Date: 1999
  • Subjects: Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4069 , http://hdl.handle.net/10962/d1006211 , Pollutants -- Biodegradation , Pollutants , Chemical reactors , Membrane reactors , Fungi -- Biotechnology
  • Description: The possibility of developing an immobilised-enzyme bioprobe, based on mushroom polyphenol oxidase, for the purely biological detection and quantification of phenolic pollutants in water was investigated. Polyphenol oxidase catalyses the bioconversion of many phenolic compounds into quinone-related coloured products. Thus, in an immobilised form, the enzyme serves as a visible indicator of the presence and concentration of phenolic pollutants in water. The objective of this research was to develop a portable, disposable bioprobe incorporating polyphenol oxidase for this purpose. The intensity of the colour changes produced by the enzyme on reaction with p-cresol, p-chlorophenol and phenol was found to increase proportionally with increasing concentrations of these substrates in solution. Immobilisation of the enzyme on various supports did not appear to significantly affect the catalytic activity of the enzyme. The enzyme was immobilised by adsorption and cross-linking on polyethersulphone, nitrocellulose and nylon membranes with the production of various colour ranges on reaction with the phenolic substrates. The most successful immobilisation of the enzyme, in terms of quantity and distribution of enzyme immobilised and colour production, was obtained with the enzyme immobilised by adsorption on nylon membranes in the presence of 3-methyl-2-benzothiazolinone hydrazone (MBTH). The enzyme, immobilised using this method, produced ranges of maroon colours in phenolic solutions and orange colours in cresylic solutions. The colour intensities produced were found to increase proportionally with increasing substrate concentration after 5 minutes exposure to the substrates. The bioprobe had a broad substrate specificity and was sensitive to substrate concentrations down to 0.05 mg/L. The enzyme activity of the bioprobe was not significantly affected in a pH range from 4 to 10 and in a temperature range from 5-25⁰C. The bioprobe activity was not affected by various concentrations of salt and metal ions and the bioprobe was able to detect and semi-quantify phenolic substrates in industrial effluent samples. These features of the bioprobe indicate that the commercialisation of such a bioprobe is feasible and this technology has been patented (Patent No. SA 97/0227). , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
  • Full Text:
  • Date Issued: 1999

The dynamics of a subtropical lake fishery in central Mozambique

  • Authors: Weyl, Olaf L F
  • Date: 1999
  • Subjects: Fisheries -- Chicamba, Lake Fisheries -- Mozambique
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5212 , http://hdl.handle.net/10962/d1004785
  • Description: Fisheries in African reservoirs are typically multi -species and in most cases the fish resource is harvested with a number of gears. These characteristics complicate their management and the development of management procedures. Typically, long time series of data on catch and effort and length- or age-based catch are not available for these fisheries. This precludes the use of data intensive methods such as multi-species virtual population analysis. The principal aim of this thesis was to develop a management procedure for African reservoir fisheries that takes into account the pertinent biological characteristics of the target species and accounts for the multi-species and multi-gear irIteractions in such fisheries. An opportunity availed itself to undertake this work on Lake ChicaIllba (19°08'S 33°08'E) a man-made hydroelectric dam in subtropical Mozambique (Manica province). The specific objectives of this study were: to obtain locality specific biological parameters for the target species in Lake ChicaIllba; to assess gear utilisation trends in the fishery through the determination of gear-selectivity, catch rate and effort for each of the principal gears used in the fishery; to assess the fishery using traditional per-recruit models and to test existing and new per-recruit models that account for the multi-species and multi-gear nature of the fishery and to determine the adequacy of each of these approaches in the determination of suitable target reference point (TRP) exploitation rates. The three principal specIes in Lake Chicamba are the introduced largemouth bass, Micropterus salmoides, and two cichlids the Mozambique tilapia, Oreochromis mossambicus and the redbreast tilapia, Tilapia rendalli. Sectioned otoliths were used for age and growth determination. Marginal zone analysis showed that annulus formation in all three species occurred during winter. The maximum-recorded age was 5 years for M. salmoides, 16 years for T. rendalli and 10 years for O. mossambicus. Growth of the three species was best described by the 3 parameter von Bertalanffy growth model as ℓa = 465.51 (1 - e⁻ₑ·ₑ⁷⁵⁽a⁺⁰·⁰⁰⁹⁾ mm FL for M salmoides; ℓa = 238.74 (1 - e⁻⁰⁶³⁶⁽a⁺⁰·⁹⁰⁵⁾) mm TL for T. rendalli; and ℓa = 266.06 (1 - e⁻⁰⁷⁹⁰⁴⁽a⁺⁰·²⁶⁹⁾) mm TL for 0. mossambicus. Female T. rendalli attained 50%-maturity at 2.89 years, while O. mossambicus matured at 2.83 years and M. salmoides at 0.9 years. Both cichlid species spawned throughout summer while M. salmoides had a very short spawning season from August to September. The total annual mortality rate (Z) for M. salmoides in Lake Chicamba was 1.27 yr⁻¹, the mean empirical estimate of natural mortality (M) was 0.73 yr⁻¹, and fishing mortality (F) was calculated at 0.54 yr⁻¹. For T. rendalli Z = 0.31 yr⁻¹, M = 0.20 yr⁻¹, F = 0.11 yr⁻¹ and for 0. mossambicus Z= 0.62 yr⁻¹, M= 0.38 yr⁻¹, F= 0.24 yr⁻¹. The three species exhibited reproductive traits, which implied a high reliance of recruitment on spawner stock (nest guarding in T. rendalli and M. salmoides and mouthbrooding in O. mossambicus). For this reason it was decided that the cichlid fisheries should be managed using TRPs which maintained the spawner biomass-per-recruit at 50% (FSB50) of pristine levels. However, based on good evidence it was hypothesised that the high rate of fishing mortality helped to maintain the fast growth rate of M. salmoides. It was, therefore, decided to manage this species at a TRP of F SB40. The three most important fishing sectors were the gill-net, seine-net and hook-and-line fisheries. The total catch for 1996 was 223 t. The gill nets selected all three species at a size/age approximating 50%-maturity while the seine-net and hook-and-line fisheries selected mainly juvenile fishes. There was strong evidence to suggest that seine net fishing also disrupted spawning. It was shown that the 'traditional' single-species per-recruit models were unsuitable to assess multi-species and multi-gear reservoir fisheries. Since existing multi-species/multifishery yield-per-recruit models were not capable of defining FsB(x) TRPs, a new multispecies/ multi-fishery spawner-biomass-per-recruit approach was developed. This approach allowed for the simulation of the response of spawner biomass-per-recruit to changes in effort in the three fishery sectors, simultaneously. The models showed that the spawner biomass-per-recruit, at current effort levels, was higher than the suggested TRP for the three species. However, it was shown that an increase of 10% in current total effort would reduce spawner biomass-per-recruit to below the recommended TRP levels. With the closure of the seine-net fishery, gill-net effort could be increased to 338 fishers (340 for management purposes) and effort in the hook-and-line fishery could be increased by 30% before the TRP was reached. To maintain the fish stocks above TRP levels, effort control was considered to be the most effective management method. The main recommendations for Lake Chicamba were to close the seine-net fishery, to limit the gill-net fishery to 340 fishers (using 137-m long x 3-m deep gill nets) and to maintain the open access nature of the hook-and-line fishery. The multi-species/multi-fishery per-recruit approach allows for the meaningful simulation of various scenarios and provides relatively robust management options. In the absence of long time series of effort and age- or length-based catch data, this approach was considered as the most suitable assessment method for multi-species/multi-gear African reservoir fisheries.
  • Full Text:
  • Date Issued: 1999
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