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Cytogenetic studies of Pseudobarbus and selected Barbus (Pisces: Cyprinidae) of southern Africa

  • Authors: Naran, Daksha
  • Date: 1997
  • Subjects: Cyprinidae
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5252 , http://hdl.handle.net/10962/d1005095 , Cyprinidae
  • Description: The aim of this study was to explore the karyology of temperate southern African barbine species in order to determine the extent and significance of polyploidy within the species. The study presents an optimised in vivo karyological protocol for the small barbines. The analysis of chromosomal data was explored using two approaches; measured (quantitative) and visual (qualitative). The karyology of 16 species of Barbus and six species of Pseudobarbus (Pisces: Cyprinidae) is reported. The study represents an almost complete (22/23 species) karyological survey of the temperate barbines. Chromosome number, arm numbers (NF) are recorded and karyotype morphology described for all species. Nucleolar organiser regions (NOR)s of 18 species have been examined by silver staining. Seven different AgNOR phenotypes occur among the species examined. Chromosome complements of the different species indicate at least three ploidy levels; diploid, tetraploid and hexaploid. Higher ploidy levels are represented in 78% (18/23) of species within the temperate fauna. This finding is remarkable, in the light of global proportions of cyprinid karyotypes, and provides an opportunity to shed further light on the evolution of polyploidy in barbine cyprinids. Results show that morphologically defined species complexes have distinct karyotypes, and most probably form cohesive phyletic clades. A phylogenetic tree was constructed using traditional morphological characters and tested against karyological data. The results suggests that similar ploidy states do not necessarily indicate close relationship between species. This supports a hypothesis of polyphyly for the African barbine cyprinids and also provides independent support for species complexes such as the "chubbyhead barb group" and the Pseudobarbus lineage. The broader implications of karyological findings are discussed within the context of African barbines and recommendations for further cytogenetic research are provided.
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  • Date Issued: 1997

Debate on globalisation

  • Authors: COSATU
  • Date: 1997
  • Subjects: COSATU
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/172083 , vital:42156
  • Description: At the Cosatu National Congress, a debate around the issue of globalisation erupted. At the core of the debate was whether the federation was opposed to globalisation or not. Some unions fell that as a federation we should be opposed to globalisation and all what it represents. Others felt that we should be opposed not to globalisation but its negative effects or the current form of globalisation.
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  • Date Issued: 1997

Dennett's compatibilism considered

  • Authors: Puttergill, Julian Gatenby
  • Date: 1997
  • Subjects: Dennett, Daniel Clement , Intentionality (Philosophy)
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2718 , http://hdl.handle.net/10962/d1002848 , Dennett, Daniel Clement , Intentionality (Philosophy)
  • Description: My basic concern in this thesis is to examine the details behind Dennett's attempt to reconcile the notions of mechanism and responsibility. In the main this involves an examination of how he tries to secure a compatibilism between mechanistic and intentional explanations by developing a systematised conception of intentional explanation. I begin by briefly discussing the various notions needed for understanding what is at stake in the area and where the orthodoxy on the matter lies. As such the first three sections of the work are not focussed on Dennett's work itself and playa stage-setting role for the deeper work to follow. These notions include the likes of the rationale behind attributing moral responsibility, agency and action, mechanism and mechanistic explanation, and intentional explanation. I suggest that the basic intuition regarding mechanism and responsibility is such that the two are seen to be incompatible with each other. The main reason for this lies in an intuition that mechanism undermines intentional explanation and so renders the notion of action largely empty. Action, I show, is at the heart of our attribution of responsibility and is dependent on intentional explanation. Having presented these issues, I turn to the details of Dennett's 'intentional systems theory'. I argue that Dennett attempts to avoid the intuition that mechanism is incompatible with responsibility by developing a specialised account of intentional explanation. Dennett calls it the intentional stance. r highlight the two important features of this intentional stance, namely rationality and intentionality. r show that Dennett's position on rationality and intentionality is such that it does allow him to secure an explanatory compatibilism between mechanism and his sort of intentional explanation. I argue, however, that his sort of intentional explanation does not fulfil our requirements for ascribing agency or moral responsibility. This is accomplished in part by developing alternative conceptions of the two notions. Out of this I develop a different sort of intentional stance, which I call the folk stance. I show finaIly that Dennett's compatibilist move is incapable of being applied to the folkstance from which we do in fact make attributions of responsibility, and so conclude thatDennett fails to make the case for reconciling mechanism and responsibility.
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  • Date Issued: 1997

Design, synthesis and evaluation of novel, metal complexing agents

  • Authors: Hagemann, Justin Philip
  • Date: 1997
  • Subjects: Ligands Metal complexes
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4307 , http://hdl.handle.net/10962/d1004965
  • Description: Various chelating ligands have been designed and synthesised; these include amino-amide ligands, tetraacetic acid systems and sulfur-containing amide ligands. Difficulties in the synthesis and purification of the amino-amide ligands were largely overcome, permitting the mono acylation of ethylenediamine and the synthesis of bis(2-aminoethyl)-2-benzylpropanediamide. Novel tetraacetic acid ligands, based on the propanediamide backbone and targeted as EDTA analogues, were obtained from their methyl and benzyl esters; but the instability of the tetraacids prevented their full characterisation. Bidentate, tridentate and tetradentate sulfur-containing monoamide ligands, based on the ortho-thio acetanilide moiety, were designed to specifically chelate platinum and palladium in the presence of base metals. In their synthesis, thiocyanation was used to introduce the orth-thio group on para-substituted anilines, and further functionalisation was achieved via appropriate protection of nucleophilic sulfur moieties. A range of tetradentate, sulfur-containing diamide ligands was also synthesised by reacting substituted 2-mercaptoacetanilides with 1,2- dibromoethane. Novel ligands were characterised by spectroscopic (¹H and ¹³C NMR; IR and M S) techniques and elemental (combustion and high resolution MS) analysis. Computer modelling and ¹H NMR chemical shift data have been used to explore the conformational preferences of the sulfur-containing acetanilide ligands. The macrocyclic ligands and systems with ortho-methylthio substituents appear to exhibit the greatest degree of coplanarity of the aromatic and amide functions. Solvent extraction studies revealed that the sulfur-containing amide ligands selectively extracted palladium(II) from platinum(II), copper(II}, nickel(II} and cobalt(II}. Even though the palladium(II} was extracted from an acidic medium, certain monoamide ligands were able to complex palladium(II) through their sulfur and deprotonated amide nitrogen donors, a trithia monoamide ligand being observed to displace all the chloride ligands on palladium to form a monomeric tetracoordinate complex. The diamide ligands, however, appeared to favour extraction of palladium(II) by coordination through their sulfur donors, forming 5-membered sulfur-sulfur chelates. In basic media (pH 8-9), selected sulfur-containing monoamide and diamide ligands have been shown to complex platinum(II) and palladium(II) through their sulfur and deprotonated amide nitrogen donors. At neutral pH, a dimercapto monoamide ligand has been shown to complex platinum from cisplatin with partial expulsion of the ammine ligands, while a macrocyclic trithia monoamide ligand has been observed to complex platinum from tetrachloroplatinate with concomitant deprotonation of the amide nitrogen. Where possible, the complexes were characterised by infrared and ¹H NMR spectroscopy and have also been studied using the computer modelling soft-ware programmes, Momec® and Hyperchem®.
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  • Date Issued: 1997

Detached harmonies : a study in/on developing social processes of environmental education in eastern southern Africa

  • Authors: O'Donoghue, Rob
  • Date: 1997
  • Subjects: Environmental education -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1939 , http://hdl.handle.net/10962/d1007726
  • Description: Long-term social processes are explored to examine the shaping of environmental education in eastern southern Africa. The study opens with early Nguni social figurations when 'to conserve was to hunt.' It then examines colonial conservation on the frontiers of imperial expansion and developing struggles for and against wildlife preservation. These processes shaped an inversion of earlier harmonies as declining wildlife was protected in island sanctuaries of natural wilderness and 'to conserve was not to hunt.' Inside protected areas, conservation management struggles shaped new harmonies of interdependence in nature, enabling better steering choices in developing conservation science institutions. Here more reality congruent knowledge also revealed escalating risk which was linked to a lack of awareness amongst communities of 'others' outside. Within continuing conservation struggles, education in, about and for the environment emerged as new institutional processes of social control. The study examines wilderness experience, interpretation, extension, conservancies and the development of an environmental education field centre, a teacher education programme and a school curriculum. Naming and clarifying the emergent education game for reshaping the awareness and behaviour of others is examined within a developing figuration of environmental education specialists. Particular attention is given to academic and statutory processes shaping environmental education as a field of objective principles and rational processes within modernist continuities and discontinuities into the 1990's. An environmental education field centre, an earth-love curriculum and research on reserve neighbour interaction are examined as political sociologies developing within a declining power gradient and wide ranging socio-political change. Into the present, a final window on a local case of water pollution examines shifting relational dynamics revealing how environment and development education models of process may have little resonance amidst long-term socio-historical struggles and shifting controls over surroundings, others and self. A concluding review suggests that grounded critical processes engaging somewhat blind control over surroundings may yet reshape self-control and social control amongst others. The trajectories of these clarifying struggles must remain open-ended as sedimented myth and memory is reshaped within ongoing processes of escalating risk and global intermeshing.
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  • Date Issued: 1997

Determination of the optimum environmental requirements of juvenile marine fish : the development of a protocol

  • Authors: Deacon, Neil
  • Date: 1997
  • Subjects: Mariculture Fishes -- Ecology Grunts (Fishes) -- Ecology Pomadasys -- Ecology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5254 , http://hdl.handle.net/10962/d1005097
  • Description: The spotted grunter, Pomodasys commersonnii, has been identified as a candidate species for mariculture in South Africa due to its high market demand and apparent biological suitability for culture. In common with most other potential mariculture species the spotted grunter has an estuarine juvenile phase. In this respect, the difficulties encountered in determining the optimum environmental requirements of spotted grunter are applicable to the majority of other potential mariculture species. Due the variability of estuarine habitats determination of the optimum environmental requirements of estuarine species under laboratory conditions are a prerequisite to subsequent evaluation of aquaculture potential. Therefore, using the spotted grunter as a representative of a typical potent ial mariculture species, the aim of this study was to contribute to the protocol for evaluating the environmental requirements of potential aquaculture species. The growth of fish is dependent on the relationship between food intake, metabolism and environmental factors. In this relationship, environmental factors do not act on growth per se, but rather act through metabolism on growth. Consequently, the environmental factors affecting the growth of a fish species can be classified into functional categories according to their respective influence on metabolic processes. Five functional categories are recognised, namely: controlling, limiting, masking, directive and lethal factors. In this study, the functional categories were sequenced to develop a theoretical protocol for determining the optimum environmental requirements of potential mariculture species under artificial conditions. It was hypothesised that the correct sequence for experimentally determining the optimum environmental requirements of a species should correspond to theoretical protocol. The hypothesis was tested from the experimental investigation into the individual effects of temperature, salinity, light intensity, photoperiod and food intake on growth performance of juvenile spotted grunter. The investigations quantified the relative effects of controlling, masking, directive and limiting factors on growth performance. The results of the studies were statistically compared to obtain a ranking of the effects of the environmental factors (e.g. temperature, salinity, etc.) on growth performance of juvenile spotted grunter. The statistical ranking facilitated the formulation of a second protocol for sequentially determining the optimum environmental requirements of a species. The second protocol was derived purely from the experimental data. Based on the corroboration between the theoretical protocol and that formulated from the experimental investigations, the hypothesis was accepted. Confirmation of the protocol for examining the effects of controlling, limiting, masking and directive factors provided a basis for the development of a preliminary experimental sequence for determining the optimum environmental requirements of juvenile marine fish. In the development of the experimental sequence, the protocol was interpreted in conjunction with the experimental methods used to determine the effects of environmental factors on the growth of juvenile spotted grunter. The experimental sequence provides a logical frame work within which the optimum environmental requirements of other marine fish species can be determined. In addition, evaluation of growth performance by this method provides a basis for comparison of the mariculture potential between species.
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  • Date Issued: 1997

Die ontwikkeling van 'n plattelandse tak van die ACVV 1900-1996

  • Authors: du Plessis, Alette Marjorie
  • Date: 1997
  • Subjects: Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
  • Language: Afrikaans
  • Type: Thesis , Masters , MSocSc
  • Identifier: vital:694 , http://hdl.handle.net/10962/d1006387 , Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
  • Description: Die ACVV is een van die oudste gesinsorgorganisasies in Suid-Afrika en die oudste vrou-welsynsvereniging. Die organisasie is in 1904 gestig, maar dit word bewys dat dit in werklikheid ouer is. Die ontstaan is die gevolg van noodlenigingswerk wat in sovele Kaaplandse dorpe en stede aangepak is deur die Afrikaanse vroue om sover moontlik die smarte van die Anglo-Boere-oorlog te verlig. Dit was veral in die jare 1900 en 1902 toe plaaslike komitees in verskeie dorpe gestig is om eetware, klere en leesstof aan die krygsgevangenes in die kamp te stuur en later aan die vroue in konsentrasiekampe. Hieruit kan afgelei word dat die organisasie ontstaan het met oorlewing as oogmerk. Toe die oorlog verby is, het die begeerte posgevat om van hierdie komitees iets blywends te maak. Lambrechts en Theron (1959:31) bepaal dat daar drie tydperke onderskei word by die nagaan van die werksaamhede van die ACVV. In die bestudering van die plaaslike omstandighede word die stelling as waar bewys, maar word die tydperke aangepas om die situasie in 'n wyer spektrum waar te neem. Die eerste tydperk word hoofsaaklik gekenmerk deur die groei van die vereniging en die reelings wat getref is vir die doeltreffende organisasie van die werk wat verrig is deur vrywillige werkers. Die tweede tydperk val saam met 'n algehele nuwe benadering teenoor welsynswerk wat gevloei het uit die vermeerderde kennis en studie van Sosiale Wetenskappe en die vraagstuk van verarming in Suid-Afrika na die jare van droogte en depressie. 'n Derde tydperk is geëidentifiseer waarin die land tred gehou het met die wereldtendens waarin die staat 'n groter aandeel in welsynsdienste begin neem het. 'n Toenemende toepassing van die beleid van staatshulp aan partikuliere organisasies is 'n erkenning van staatsweë dat daar bepaalde take is wat beter deur hierdie organisasies vervul kan word. Dit het ACW-takke in staat gestel om maatskaplike werkers aan te stel in gesubsidieerde poste. Die ACVV se dienste het gedurig ontwikkeling getoon en het noodleniging, gesinsorgdienste, groepdienste en residensiële sorg ingesluit. Dienste het sekondêr ontwikkel en baie klem is op bejaardesorg geplaas wat onder andere die oprigting en bestuur van tehuise en dienssentrums tot gevolg gehad het. Gesinsorgwerk vorm die eintlike kern van die werksaamhede van die ACVV, want al sy ondernemings het ten doel die bevordering van 'n gesonde gesinslewe. Dienste van die vereniging aan die individuele gesinslid het steeds ten doel om beter by sy gesin, en gevolglik ook beter by die samelewing aan te pas. 'n Duidelike ontwikkeling word beskryf wat vanaf 1990 tot 'n punt van verdere veranderinge gedryf word deur omstandighede buite die ACVV. Die belangrikste hiervan is 'n dramatiese verandering in regeringsbeleid waarby die ACVV moes aansluit. Dit het wesentlike aanpassings meegebring op die gebied van werksarea en die kliêntesisteem, aangesien die ACVV in die verlede hoofsaaklik in die behoeftes van die blanke kultuurgroep voorsien het. Later het subsidievereistes die vereniging verhoed om buite hierdie beperkings te werk. Die aanpassings het egter nie tot gevolg gehad dat die vereniging doelstellings, waardes en norme moes laat vaar nie. Verskeie rolspelers is betrokke by praktiese en basiese dienslewering tot besluitneming op die hoogste vlak. Die ACVV se struktuur het grootliks dieselfde gebly met die Kongres as hoogste gesag. Die dienste van die Hoofbestuur het sodanig uitgebrei dat dit leiding kon bied aan takke op grondvlak. Dit is deurgaans duidelik dat die vrywillige werker binne die organisasie die kern en basis vorm waarop die vereniging voortbestaan. Die ACVV sal in die toekoms steeds In rol het om te vervul in 'n veranderde omgewing wat uitdagings bied vir dienslewering en waar uitgebreide behoeftes ten opsigte van maatskaplike ontwikkeling bestaan
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  • Date Issued: 1997

Eastern Cape bells (letter)

  • Authors: Lewis, Colin A
  • Date: 1997
  • Language: English
  • Type: Article
  • Identifier: vital:6181 , http://hdl.handle.net/10962/d1012375 , http://www.ringingworld.co.uk
  • Description: Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa. This correspondence was sparked by the author's article: "Bells and Bellfounders of the Eastern Cape, South Africa" which appeared in The Ringing World No. 4477. 14th February 1997, pp. 161-162.
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  • Date Issued: 1997

Eco-ethology of shell-dwelling cichlids in Lake Tanganyika

  • Authors: Bills, Ian Roger
  • Date: 1997
  • Subjects: Cichlids -- Africa, East , Cichlids -- Tanganyika, Lake , Fishes -- Behavior
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5265 , http://hdl.handle.net/10962/d1005109 , Cichlids -- Africa, East , Cichlids -- Tanganyika, Lake , Fishes -- Behavior
  • Description: Observations of habitats are reported. A series of underwater experiments were conducted in natural habitats to answer questions concerning a) why Lamprologus ocellatus and Lamprologus ornatipinnis bury gastropod shells refuges into the substrate, and b) to examine interspecies differences in shell-using behaviours. Some behaviour patterns were analysed using phylogenetic methods. Lamprologus ocellatus and L. ornatipinnis responded to new shells in a variety of ways, shells were moved, buried (and used) or hidden (buried and not used). How shells are utilised seems to be dependant on a complex of factors such as the size and quality of new the shell and the number already in the territory. Shell use may also be affected by neighbour species, sex, size and predation levels. There are interspecific differences in the size of shells used and the methods of shell use. The latter results in species-characteristic shell orientations, vertical burial in L. ocellatus and horizontal burial in L. ornatipinnis. Shell orientation does affect other species/use of shells. Shell movement and vertical orientation appear to be apomorphic while shell hiding and burial are pleisiomorphic within the genus Lamprologus. Numerous cues are involved in stimulating shell burial. Most of these cues are actively sought by the fish by external and internal inspections. Shell burial therefore appears to be a method of reducing the information gathering ability of potential shell-dwelling competitors. Shell burial can therefore be regarded as an investment process which enhances the residents ability to defend its territory. Males can also control the distribution of open shells within teritories and thus control mate access to shells. This behaviour could be a significant factor in the evolution of marked sexual dichromatism exhibited within the genus.
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  • Date Issued: 1997

Ecological interaction between the introduced and native rock-dwelling cichlid fishes of Lake Malawi National Park, Malawi

  • Authors: Munthali, Simon Muchina
  • Date: 1997
  • Subjects: Cichlids -- Nyasa, Lake
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5266 , http://hdl.handle.net/10962/d1005110
  • Description: More than twenty years ago, over twenty species of the rock-dwelling cichlid species (Mbuna) were translocated from the northern Lake Malawi, where they are endemic, to Thumbi West Island, Lake Malawi National Park, in the southern part of Lake Malawi. Among these species, Cynotilapia afra, Pseudotropheus callainos and Pseudotropheus tropheops 'red cheek' are strongly territorial, and have increased substantially in number and are widely distributed, particularly in the three to seven metre depth band of the rocky habitats at the Island of Thumbi West. It is feared that the increase in population density of translocated species (hereafter referred to as introduced species) may be at the expense of ecologically equivalent native species which could be eliminated. In this thesis the following key hypotheses have been tested: (i) that the introduced species having originated from a region of Lake Malawi which is generally poor in nutrients and introduced in an area which is richer in nutrients, would cope better than the native species during periods of nutrient scarcity which occur frequently, often seasonally in oligotrophic lakes, such as Lake Malawi; (ii) that the introduced species are fitter than their ecologically equivalent native species in the acquisition of territorial space in which they breed, feed and seek shelter, and (iii) that introduced and native species coexist by utilizing different microhabitats. Results show that: 1. the introduced species, P. callainos and P. tropheops 'red cheek' may have responded positively to enhanced nutrient availability, as they were found to have better condition factors and fecundity indices at Thumbi West Island than at sites of their origin, in the northern lake Malawi. Cynotilapia afra, P. callainos and P. tropheops 'red cheek' also maximise their life-span fecundity by starting to reproduce at relatively smaller size than the native species with which they overlap in microhabitat requirements. Similarly, their breeding peaks precede the breeding peaks of the native species with which they overlap in microhabitat requirements. Consequently, due to priority residence effects, the offspring of introduced species may have a competitive edge in the use of essential resources, e.g., refuge over the offspring of the native species whose peak-recruitment occurs later in the year. 2. There is an overlap between the introduced and native species in their microhabitat requirements. Consequently, interference competition between them for territorial sites occurs. The choice of optimal territory sites is constrained by the fact that females preferentially mate with males that defend significantly smaller holes, or crevices among the rocks, probably as a means of minimizing egg predation during spawning. 3. The population of territorial males of introduced species seems to grow exponentially, depending on the availability of suitable microhabitats, and an equilibrium between them and males of the native species may be reached. Competition for optimal territory sites seems to intensify, once the carrying capacity in a particular area has been reached, and it is at this stage that some territorial males of the introduced and native species with similar microhabitat requirements, e.g., C. afra and P. zebra, or P. tropheops 'red cheek' and its sibling native species, P. tropheops 'orange chest' displace each other. However, it seems unlikely that any of the native species which were compared with the introduced species would be driven to extinction because: (a) there is a considerable interspecific territory turn-over between the introduced and native species that overlap in microhabitat requirements. (b) Even in situations where some of the native species occur in microhabitats that are not of their preference, they occupy patches of suitable sites and are capable of breeding. (c) It has been suggested that since introduced and native species breed throughout the year and are polygamous and have intraspecifically shared paternity, they are capable of fertilizing many gravid females of their own species. Therefore, the population of native species may not be detrimentally limited by the presence of introduced species. (d) The introduced and native Mbuna species that prefer small rocks coexist in the same microhabitats, partly by feeding at different sites with different intensity and they also feed at different heights in the water column. 4. The following studies have been recommended before any management intervention, such as culling is adopted: (i). interaction between the introduced and native species in the shallow and deep rocky habitats; (ii) space utilization and survivorship of juveniles of the introduced and native species; (iii) laboratory studies to confirm the role of different nutrient regimes on the fecundity of Mbuna; (iv) the possibility of hybridization between the introduced and native species; (v) monitoring of population growth and distribution of the introduced species around Thumbi West Island should continue in order to detect their long-term effects on the native species.
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  • Date Issued: 1997

Effects of sustained elevated CO₂ concentration on two cultivars of barley (Hordeum vulgare L.)

  • Authors: Siphugu, Mashudu Victor
  • Date: 1997
  • Subjects: Barley Barley -- Growth Photosynthesis -- Research Plants -- Effect of carbon dioxide on
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4226 , http://hdl.handle.net/10962/d1003795
  • Description: The enormous burning of fossil fuel and deforestation have caused an increase in the atmospheric CO₂ concentration ([CO₂]) during the last century. This will invariably have profound direct and indirect effects on plant carbon metabolism. The majority of research on the effects of CO₂ enrichment on plants are short-term and are done on other crops, but very little have been done on barley. This project aimed to determine the effects of long-term CO₂ enrichment on photosynthesis, growth and grain yield on barley. Hordeum vulgare L. cvs Stirling and Schooner plants were grown from seeds in controlled environment chambers at ambient (350) and elevated (600) μmol molˉ¹ [CO₂]. Measurements of net assimilation rate (NAR), photosynthetic pigments content and growth parameters were started 7 days after germination (DAG) and continued until senescence. The anatomy of matured fully developed leaves was also monitored. Elevated [CO₂l resulted in an increase in NAR in the two cultivars from days 7 until 14, after which the stimulation of NAR of CO₂-enriched plants started to decrease. At the onset of senescence, NAR was almost equal in plants grown under both ambient and elevated [CO₂]. The response of assimilation as a function of internal [CO₂l (C₁) at the end of the experimental period showed a significant decrease in both the initial slope of the A/C₁ curves and the CO₂-saturated photosynthetic rates in the two cultivars. Stirling showed no significant changes in the content of chlorophyll α,chlorophyll б or in total carotenoids. However, Schooner showed a stimulation in chlorophyll α content at day 7, but decreased at day 28. Chlorophyll б and total carotenoids content were not affected by CO₂ enrichment. While total above-ground biomass was not affected by elevated [CO₂] in the two cultivars, total plant height decreased significantly after 14 days in Stirling whereas no significant change occurred in Schooner throughout the experimental period. Leaf area was not significantly affected by CO₂ enrichment in the two cultivars although the leaves in CO₂ enriched plants were slightly shorter. Anatomical studies reveal that leaf thickness was significantly increased by CO₂ enrichment in Stirling, but the increase was not significant in Schooner. Both cultivars did not show any significant effect on chloroplast morphology and ultrastructure as a consequence of elevated CO₂ exposure. No signs of starch accumulation were evident in variety Schooner, but Stirling showed some form of starch accumulation, under increased atmospheric [CO₂]. Elevated CO₂ resulted in a significant reduction by more than 50 % in the number of grain yield per plant in both Stirling and Schooner. Results from this study therefore indicate that CO₂ enrichment will not be beneficial in terms of growth and yield in this important crop.
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  • Date Issued: 1997

Environmental education : a strategy for primary teacher education

  • Authors: Wagiet, Razeena
  • Date: 1997
  • Subjects: Environmental education -- Study and teaching (Elementary) Environmental education -- Study and teaching (Elementary) -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1512 , http://hdl.handle.net/10962/d1003394
  • Description: This research focuses on environmental education in initial teacher education, and is grounded in three interlinked and widely recognised assumptions. First, that education for sustainable living can assist in resolving some environmental problems that are contributing to the environmental crises of sustainability currently facing South Africa and the rest of the world. Second, that education for sustainable living can assist in the establishment of a new environmental ethic that will foster a sustainable way of living. Third, that teacher education is a vital process for the attainment of both. These assumptions inform the aim of this research, which is to explore the potential for the implementation of education for sustainable living, and to identify a strategy for this, for initial teacher education, for senior primary school student teachers in the Western Cape. The strategy is derived following the grounded theory approach, developed through the case study method. In the process of identifying the strategy, this study establishes that there are challenges at macro, meso and micro levels that are obstructing the changes necessary for education for sustainable living. Change theory provides the basis for explaining these shortcomings, by helping to identify the barriers that might obstruct the realisation of the changes that are necessary for education for sustainable living. These challenges need to be perceived in the light of overcoming three sets of barriers in the way of the potential implementation of education for sustainable living in teacher education. First are those that can be ascribed to the formal education system that, while clinging to Western, Eurocentric values on the one hand, bave also failed to secure a policy for environmental education on the other. Second are the barriers ascribed to the teacher educators themselves, with the whole notion of their powerlessness at its core. Finally, there are the logistical barriers, which encompass, for example, time and financial constraints. With these barriers as a backdrop, to facilitate the incorporation of environmental education into initial teacher education, the study identifies a need for the development of a strategy to secure that education for sustainable living assumes its rightful place in the curriculum for initial teacher education. This framework emerges from the theory grounded in the interviewees' responses during the research, and from the theory grounded in the literature. Central to this framework is for education for sustainable living to contribute to the realisation of real change, change that would further the transformation of our conflict-riddled and inequitable society towards a more democratic and just one. This thesis demonstrates that the realisation of the changes necessary for education for sustainable living demand a reconstruction of current teacher education in order to secure and to sustain an appropriate and sound education ethic to form the basis of a trans formative teacher education curriculum for sustainable living within initial teacher education. Except formal policy, but central to overcoming these barriers, is the need for professional development programmes for teacher educators. A strategy in this regard, is outlined.
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  • Date Issued: 1997

Environmental perceptions and knowledge among political leaders in the Eastern Cape Province and some implications for environmental policy

  • Authors: Mbengashe, Pauline Maria
  • Date: 1997
  • Subjects: Environmental policy -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1517 , http://hdl.handle.net/10962/d1003399
  • Description: The environmental and development challenges facing South Africa are closely linked with the political and economic inequalities of the past. The achievement of sustainable. development will require social and political change. Protection and conservation of the environment, improving environmental knowledge and understanding, the participation of all citizens, effective environmental management, inclusive and implementable policies and legislation, are all necessary components of sustainable development. These requirements are in line with the Rio Declaration on Environment and Development and Agenda 21, a programme of action coming out of the United Nations Conference on Environment and Development (UNCED 1992) This study explores the environmental perceptions and knowledge of some representative Eastern Cape political leaders. The aim of the study was to share views on environmental issues, concerns and strategies that might lead to improved environmental understanding, informed policy change and effective environmental management. Different environmental ideologies were also explored because of the political and ideological nature of the concepts 'environment' and 'education'. Data was collected from semi-structured interviews undertaken with ten political leaders in the Eastern Cape Province Legislature. The study revealed a general awareness and understanding of environmental issues with unsupported indepth knowledge and detailed information. The political, development, social and economic dimensions of the environment were emphasised more than the ecological and physical aspects. The need for environmental information, policies and legislation was recognised. Both formal and non-formal environmental education were emphasised. The need to redefine environmental education and make it more relevant, problem solving and action oriented was also emphasised. The challenge is to improve environmental understanding and making environmental information available to political leaders, government officials and citizens in general.
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  • Date Issued: 1997

Epithermal precious metal deposits physicochemical constraints, classification characteristics and exploration guidelines

  • Authors: McIver, Donald A
  • Date: 1997
  • Subjects: Precious metals , Geothermal resources
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
  • Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
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  • Date Issued: 1997

Evaluation of the proposed FDA pilot-dose response methodology for topical corticosteroid bioequivalence testing

  • Authors: Demana, Patrick H , Smith, Eric W , Walker, Roderick B , Haigh, John M , Kanfer, Isadore
  • Date: 1997
  • Language: English
  • Type: Article
  • Identifier: vital:6356 , http://hdl.handle.net/10962/d1006047
  • Description: The American FDA has recently released a Guidance document for topical corticosteroid bioequivalence testing. The purpose of this study was to evaluate the recommendations of this document for appropriateness. The new specifications require a dose-vasoconstriction response estimation by the use of a Minolta chromameter in a preliminary pilot study to determine the parameters for use in a pivotal bioequivalence study. Methods. The visually-assessed human skin blanching assay methodology routinely practiced in our laboratories was modified to comply with the requirements of the pilot study so that visual and chromameter data could be compared. Two different cream formulations, each containing 0.12% betamethasone 17-valerate, were used for this comparison. Results. Visual data showed the expected rank order of AUC values for most dose durations whereas the chromameter data did not show similar results. The expected rank order of AUC values for both chromameter and visual data was not observed at very short dose durations. In fitting the data to pharmacodynamic models, equivalent goodness of fit criteria were obtained when several different parameter estimates were used in the model definition, however the visual data were best described by the sigmoid E[subscript max] model while the chromameter data were best described by the simple E[subscript max] model. Conclusions. The E[subscript max] values predicted by the models were close to the observed values for both data sets and, in addition, excellent correlation between the AUC values and the maximum blanching response (R[subscript max]) (r > 0.95) was noted for both methods of assessment. The chromameter ED[subscript 50] values determined in this study were approximately 2 hours for both preparations. At this dose duration the instrument would not be sensitive enough to distinguish between weak blanching responses and normal skin for bioequivalence assessment purposes.
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  • Date Issued: 1997

Exploitation of the bait organism Upogebia africana (Crustacea: Anomura) in the Knysna estuary

  • Authors: Cretchley, Robyn
  • Date: 1997
  • Subjects: Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5691 , http://hdl.handle.net/10962/d1005377 , Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
  • Description: In South African estuaries the anomuran mud prawn, Upogebia africana (Ortmann), is the main organism exploited as bait by recreational and subsistence anglers. In the Knysna estuary, three groups of bait collectors were identified on the basis of their source of income: subsistence fishermen who rely on bait-collecting and fishing for their income, supplementary anglers who catch fish to supplement their income and leisure anglers who draw no income from fishing. Two groups were identified based on the methods used: lelsure anglers who collect bait using a prawn pusher or pump and fish using a fishing rod and tackle, and non-leisure anglers who collect mud prawns using tin cans and fish with handlines. The hypothesis was erected that bait-collecting does not affect the U africana populations in the Knysna estuary. The approach adopted was to assess the distribution, density, population structure and reproductive patterns of the bait stock and to estimate the intensity of bait collection, to test the validity of the hypothesis. U africana has an extensive distribution, occupying 62 % of the available intertidal area of the Knysna estuary. Mud prawns have a broad intertidal distribution from the high water level (Spartina zone) to the shallow subtidal. The density, biomass and population structure of the mud prawns vary significantly with distance up the estuary and with tidal height on each shore. The Invertebrate Reserve supports very low densities of U africana (x = 11.7 m⁻²), whereas a relatively inaccessible centre bank in the middle reaches of the estuary appears to be a very effective natural mud prawn reserve as it supports the highest densities (x = 176.5m⁻²). The mud prawn stock of the estuary is estimated to be 2.19 x 108 prawns (82.7 tonnes dry mass). The numbers of bait collectors present per mudbank is highest on public holidays (x = 34) and higher during the summer holidays (x = 16) than during the winter (x = 4). A total of 1.858 x 106 U africana or 700.53 kg (dry mass) are removed by bait collectors annually from the 6 popular bait-collecting sites studied. This represents 8.49 % of the mud prawn stocks at these sites and 0.85 % of the entire estuary stock. 85 % of the U africana taken as bait annually, is removed by the 77.12 % of bait collectors who are non-leisure anglers. Recreational or leisure anglers are responsible for removing 14.2 %. The reproduction of female U africana in the Knysna estuary is seasonal and occurs from late July to April. There is evidence that this breeding season consists of two merging breeding cycles. The largest percentage (63 %) of ovigerous females is found in the middle reaches of the Knysna estuary at the Oyster Bank where the highest numbers of stage 1 larvae (165 m⁻³) are released. Larvae were exported from the estuary on the crepuscular ebb tide with peaks in abundance of nearly 1500 m⁻³ in November 1995 and January 1996. Although numbers caught are not significantly higher, larvae are nearly twice as abundant on crepuscular neap tides following a new moon (waxing quarter) than on those following a full moon (waning quarter). Recruitment of juvenile U africana to populations in the estuary was highest in December (45 m⁻²) and decreased over the summer. The highest numbers of recruits (31 m⁻²) were found at those sites closest to the mouth or on the main channel. Recruitment to the Leisure Isle and Thesens sites which are intensively exploited by bait collectors is high (20 - 32 m⁻²). The number of juveniles recruiting to U africana populations is estimated to be four times as high as the numbers of mud prawns taken by bait collectors. Legal methods of bait collection used in the Knysna estuary by the majority of anglers appear to cause minimal sediment disturbance and are not likely to affect the associated infauna. Illegal bait-collecting methods are however highly destructive and must be prohibited. It is concluded that the null hypothesis is acceptable, as mud prawn stocks of the Knysna estuary are not over-exploited and appear to be naturally regulated. The recruitment rate of juvenile U africana is estimated to be sufficiently high to sustain the present levels of exploitation.
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  • Date Issued: 1997

Extracellular digestion in two intertidal mussels and the role played by their gut bacteria

  • Authors: Simon, Carol Anne
  • Date: 1997
  • Subjects: Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5692 , http://hdl.handle.net/10962/d1005378 , Perna -- Digestive organs , Mussels -- Digestive organs , Spirochaeta
  • Description: The intertidal mussels. Perna perna and Choromytilus meridionalis co-occur on the southern coast of South Africa. Mussels ingest mixtures of bacteria. phytoplankton. zooplankton and detritus. with proportions varying according to availability. These bivalves filter similar-sized particles. which might result in interspecific competition. Carbohydrate-digesting enzymes of the mussels and their enteric bacteria. and bacteriolytic enzymes of the mussels were therefore examined to elucidate feeding ecology in these animals at an enzymatic level. Style enzymes of both species digested the storage carbohydrates amylose glycogen and laminarin, and the structural carbohydrate carboxymethyl cellulose (CMC). Differential rates of digestion of these carbohydrates suggests that Perna perna relies more on plankton (and possibly bacteria) than on detritus for food while Choromytilus meridionalis relies equally on all components of the seston. There may therefore be some degree of resource partitioning of the seston. The styles of P.perna had a lower specific enzyme activity. but higher protein content than those of C.meridionalis. P.perna could therefore release more glucose from a given concentration of substrate than C.meridionalis. The gut contents and tissue were examined microscopically to determine where the bacterial colonisation sites were. Bacteria were associated primarily with the gut contents but not the gut walls. of both species. The styles housed spirochaete bacteria (Crislispira sp), Perna perna housed large numbers of one species. while Choromytilus meridionalis had lower numbers of two species. Levels of infection differed between species and localities. Enteric (but not style) bacteria of Perna perna and Choromytilus meridionalis always digested the same carbohydrates as the mussels as well as the structural carbohydrates mannan and fucoidan. Activity was erratic on the structural compounds, carageenin and xylan, and absent on alginic acid or inulin. Activity on the storage carbohydrates by enteric bacteria from C.meridionalis was higher than by those from P.perna. This is probably related to the larger bacterial populations housed by C.meridionalis than by P.perna. Bacteriolytic activity by the digestive enzymes of Pema perna was higher than for Choromytilus. In P.perna it was due to a combination of different enzymes one of which is a true lysozyme. C.meridionalis did not produce a true lysozyme. Enzymes produced by the mussels and their enteric bacteria allow the mussels to utilise all components of the seston. Low endogenous enzyme activity by Choromytilus meridionalis, coupled with the high activity by its enteric bacteria, suggests that they rely more on bacterial activity to meet their dietary requirements than does Perna perna. The ability of enteric bacteria to digest carbohydrates which the mussels cannot indicates that the bacteria are endosymbiotic, although the sporadic nature of activity of some of the enzymes, and the fact that bacteria are associated with the gut contents, indicates that the relationship is only incidental.
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  • Date Issued: 1997

FAWU - Response to the White Paper On A Marine Fisheries Policy For South Africa

  • Authors: FAWU
  • Date: 1997
  • Subjects: FAWU
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/118385 , vital:34625
  • Description: This document has been written to inform Deputy President Thabo Mbeki of FAWU’s objections to the above-mentioned White Paper. It also includes FAWU’s recommendations for changing the policy. The fishing industry in South Africa is an Apartheid creation. Like other aspects of our society, it needs to be completely transformed and restructured. Currently, the industry is marked by: Monopolised control of every aspect of the fishing value-chain: from production to processing to marketing to distribution; Highly restricted access to the resource by historically disadvantaged members of our society; and Disempowered communities who originally had unrestricted access to marine resources. The above conditions have been created by a process of systematically violating the human rights of fishers and fishing communities. A new White Paper on Fisheries has the potential to change this in a sustainable economic and environmental way. Unfortunately, the 1997 White Paper on Fisheries does not adequately address the legacy of history. In fact, there are more similarities in this Paper to the 1988 Sea Fisheries Act than there is to any framework of transformation. One such framework was put forward by the Fishing Policy Development Committee (FPDC). However, it seems that key aspects of the FPDC’s recommendations were ignored. This is unacceptable.
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  • Date Issued: 1997

FAWU Media Campaign

  • Authors: FAWU
  • Date: Sep 1997
  • Subjects: FAWU
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/118489 , vital:34638
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  • Date Issued: Sep 1997

First-row transition metal phthalocyanines as catalysts for water electrolysis

  • Authors: Chebotareva, Natalia , Nyokong, Tebello
  • Date: 1997
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/293391 , vital:57081 , xlink:href="https://doi.org/10.1016/S0013-4686(97)00033-9"
  • Description: Modification of carbon electrodes with first row transition metal phthalocyanines results in the lowering of the potentials needed for water electrolysis in basic media, by 600 to 700 mV when compared to unmodified carbon electrodes. Nickel(II), cobalt(II) and iron(II) phthalocyanines show higher catalytic activity than zinc(II), manganese(II), copper(II) and metal free phthalocyanines.
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  • Date Issued: 1997
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