M.Sc. / Please refer to full text to view abstract

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The species Haliotis midae is the only commercially exploitable abalone species of the six found in the South African coastal waters. This species is under substantial pressure from both legal and illegal harvesters, to such an extent that it could be commercially extinct within four years. Efforts to alleviate the pressures on the natural populations of both illegal and legal harvesting are being made. The genetic management systems for abalone farming and ranching activities should be carefully evaluated. The loss of genetic diversity and the risks of contaminating the gene pools of natural populations in the vicinity of a farm should be minimized. Genetic evaluation studies will be at great importance to acquire the necessary data needed for genetic diversity and differentiation analysis. The aim at this study was to develop species-specific microsatellite DNA markers to assess the genetic diversity and differentiation within and between the brood stock and commercial stock of the Sea Plant Products abalone farm (Hermanus, Republic of South Africa) and natural populations related to the brood stock. The species-specific DNA markers were also used for parentage assignments within the tarm population (first for abalone) and preliminary OTL (quantitative trait loci)-discovery analysis studying growth rate segregation. Samples were taken of the farm's brood stock and commercial stock (Rows 2, 3, 4) as well as from two natural populations (Saldanha Bay and Black Rock) related to the brood stock. Various statistical parameters and software packages were used to assess genetic diversity and differentiation, to infer parentage and to look for OTL's. Eight species-specific microsatellite DNA markers were designed and used for data analysis. Data analysis showed a loss at genetic diversity from the brood stock to the commercial stock caused by the subdivision of the original brood stock into rows and the differential contributions of parents to the offspring. No genetic differentiation (Fst) was detected between the farm and natural populations, except for the offspring of Row2. levels of inbreeding (ns) were high for all loci within the populations. Thirty-eight percent of all studied offspring were confidently assigned to a couple. The preliminary QTldiscovery suggested the segregation of a number of alleles and genotypes with growth rate. The study concluded that the commercial abalone population of the Sea Plant Products abalone farm holds no threat to the disruption of the genetic diversity of the natural populations. It is proposed that the farm implement a rotational breeding program to increase the genetic diversity of the commercial population. Any newly acquired brood stock must be profiled before their introduction into the breeding program to assess the influence of the animals on the current levels of genetic diversity within the farm. The accuracy and reliability of parentage assignments and QTl-discovery need to be optimised by adding more loci and sampling more animals or even by trying and developing new methods. / AFRIKAANSE OPSOMMING: Van die ses perlemoen spesies wat langs die Suid-Afrikaanse kus gevind word, is die spesie Haliotis midae die enigste een wat van kommersiële belang is. Wettige, sowel as onwettige versameling, plaas hierdie spesie onder sulke geweldige druk dat dit dalk binne vier jaar verlore kan wees vir die kommersiële bedryf. Verskeie strategieë word tans geïmplimenteer om hierdie druk te verlig. Die genetiese bestuurstrategieë binne perlemoen plase moet deeglik ondersoek word. Die verlies aan genetiese diversiteit en die moontlikheid vir die kontaminering van die natuurlike populasies in die omgewing van die plaas se geenpoel, moet uitgeskakel word. Genetiese evaluasies sal van groot belang wees om die nodige data vir genetiese diversiteit- en differensiasie-analises te verkry. Die doel van die studie was om spesies-spesifieke mikrosatelliet DNA merkers te ontwikkel wat gebruik sou word om die genetiese diversiteit en differensiasie binne en tussen die broei diere en die kommersiële diere van Sea Plant Products se perlemoen plaas (Hermanus, Republiek van Suid- Afrika) en die natuurlike populasies wat verwant is aan die broei diere, te bepaal. Die spesies-spesifieke DNA merkers is ook vir ouerskap-bepalings binne die plaas se populasie gebruik, asook vir voorlopige OTL (quantitative trait locI) - ontdekking met betrekking tot groeitempo segregasie. Monsters van die plaas se broei diere en kommersiële diere (Ry 2, 3, 4) asook van twee natuurlike populasies (Saldanha Baai en Black Rock) wat verwant is aan die broei diere, is geneem. 'n Verskeidenheid van statistiese parameters en sagteware pakette is vir die genetiese diversiteit- en differensiasie-analises, vir ouerskap-bepalings en vir die opspoor van OTL's gebruik. Agt spesies-spesifieke mikrosatelliet DNA merkers is ontwerp en toe gebruik vir die data analises. 'n Verlies aan genetiese diversiteit vanaf die broei diere na die kommersiële diere is deur die data analises uitgewys. Dit is veroorsaak deur die verdeling van die oorspronklike broei diere in rye en die differensiële bydraes deur die ouers na die nageslag. Geen genetiese differensiasie (Fst) is tussen die plaas se populasie en die natuurlike populasies gevind nie, maar die nageslag van Ry 2 het wel differensiasie getoon. Die vlakke van inteling (Fis) was hoog oor alle lokusse binne alle populasies. Agt-en-dertig persent van die nageslag wat bestudeer is, was suksesvol met 'n ouerpaartjie geassosieer. Die voorlopige OTL-ontdekking studie toon die potesiële segregasie van 'n aantal allele en genotipes saam met groeitempo. Die bevindinge van die studie is dat die kommersiële populasie op die Sea Plant Products perlemoen plaas, geen bedreiging vir die versteuring van die natuurlike populasies se genetiese diversiteit inhou nie. Daar is voorgestel dat die plaas 'n rotasie-basis broeiprogram moet implimenteer om sodoende die genetiese diversiteit van die kommersiële populasie te verhoog. Enige nuwe broei diere se genetiese profiel moet ook voor die tyd ondersoek word om te sien wat se effek hierdie diere op die huidige genetiese diversiteit van die kommersiële populasie sal hê. Die akkuraatheid en betroubaarheid van die ouerskap-bepalings en OTL-ontdekking moet optimiseer word deur of meer lokusse te bestudeer, of meer diere in analises te gebruik of selfs om nuwe tegnieke te probeer of te ontwikkel.

The principal aim of this study was to establish the biological and environmental parameters governing the successful and sustainable cultivation of mussels in Saldanha Bay. The environmental study investigated seston, chlorophyll-a and particulate organic matter (POM) levels, water temperature dissolved oxygen and salinity levels in the bay and water flow in and around the rafts. The biological part of the study investigated the efficiency of food extraction, growth rates, mussel condition, fouling and production and yield on a rope, raft and farm scale. Saldanha Bay is well suited for the culture of mussels, particularly Mytilus galloprovincialis and Choromytilus meridionalis. Water temperature and salinity in Saldanha Bay were found to be near optimal for mussel culture. POM and chlorophyll-a levels were found to be high due to primary production resulting from the nutrient rich upwelled water outside Saldanha Bay. The mean levels of chlorophyll-a (8,6μg/l) represent 6%, by mass, of the total POM. On a bay scale the POM remained above the mussels maximum requirements (pseudofaeces threshold) during the study period. Mussels showed a preference for the phytoplankton portion of the POM. Approximately 40% of the chlorophyll-a was extracted from the water by the mussel farm. The efficiency of food extraction increased with mussel age. Rafts with seed mussels younger than 2 months, 3 to 4 months, 5 to 6 months and older than 6 months extracted 32%, 55%, 85% and 92% of the available chlorophyll-a respectively. An increase of rope spacing on the rafts resulted in 37% more chlorophyll-a and 30% more particle volume reaching the lee of the raft. Ambient water currents in the bay show flow rates of up to 22cm per second. However, on entering a raft with a rope spacing of 60cm, the water flow is attenuated by 90%. Increasing the rope spacing to 90cm resulted in a water flow attenuation of 72%. The increase in rope spacing ensures that the mussels in the centre of the raft are feeding on food levels close to, or above, the pseudofaeces level. Mussel growth rate at a rope spacing of 90cm is significantly improved as a result of the increased food delivery. There are other factors, however that effect mussel growth. Growth rates were found to be better in summer than in winter. The reduced winter growth rate is possibly due to competition with the maturing fouling organisms which settle in mid to late summer. Fouling by mussel spat and Ciona intestinalis is seasonal, occurring from December to May. C.intestinalis is prevalent in the centre of the farm and rafts as low energy waters are preferred by this species. Mussel spat settles mainly on the periphery of the farm and the rafts. Competition with fouling organisms reduces growth and increases mortality of the cultured mussels. Results indicate that the present spacing of rafts, (1 raft per hectare) is adequate under existing conditions. Any new farms should maintain batches of 50 rafts with channels between them to ensure water current penetration into the furthest reaches of the farm. Rope spacing on the rafts should be increased to between 60cm and 90cm. Mussel density should be regulated according to mussel size and fouling should be controlled to maintain yields.

M.Sc. (Zoology) / Please refer to full text to view abstract

Bibliography: p. 207-227. / The broad theoretical concern of the thesis is to elucidate the relationship between material culture and social relations, and to counter the analytical separation of cultural form and social practice, which is a pervasive problem in archaeology and material culture studies in general. This problem is addressed with reference to museum practice, focusing in particular on the social role of artefacts in two contextual domains - that of everyday life, as interpreted in ethnographic fieldwork, and that of a museum, which is in itself a complex cultural artefact. These two contexts are linked by the concept of recontextualization, which I suggest is a pivotal process in both museum practice and archaeology. The theory of 'structuration', as formulated by Anthony Giddens, is drawn on to overcome the problematic separation of cultural objects from social subjects. This leads to the conceptualization of meaning in material culture as being socially constituted and context-related, and the relationship of material culture to social relations as being one of mediation rather than objective reflection. Emphasis is thereby given to material culture as a resource that is actively implicated in the construction of social relations and identity. This theoretical approach is applied in two field studies and two museum studies. The former, undertaken in Transkei and the Transvaal Lowveld, investigate material culture in the social matrix of everyday use; the latter, undertaken with reference to the Ethnography section of the South African Museum, illustrate the process of recontextualization, which I regard as operating at both physical and cognitive levels. It is argued that processes of recontextualization, inherent in museum practice, inevitably change both context and the object-subject relationship, and therefore alter the range of meanings that objects evoke once located in a museum. Despite the apparent authenticity of exhibited artefacts, I argue that museum representations are composite artefacts of museum practice, rather than objective reflections of reality. I suggest that reflexive awareness of professional practice as social practice should be built into both archaeological texts and museum representations, through which knowledge of the social past is conveyed to the general public. This is consistent with the argument throughout the dissertation for an integration of object and subject, and a recognition of human agency, past and present. In conclusion, I argue for a more sensitive, reflexive approach to museum practice that would encourage an awareness of social context, and invite a more active participation by viewers in the generation of meaning. The dissertation is a contribution to this end.

Bibliography: pages 127-137. / The original aims of this thesis were to analyze all the material remains from the previous excavations and collate all written reports on Andriesgrond Cave. Only one article has been written on Andriesgrond Cave (Parkington 1978), while several articles have referred to single unpublished reports or additional projects. Artefacts are analyzed and grouped according to their relevant chapters, and in the conclusion an interpretation of these finds is given in conjunction with social psychological theory of stress coping strategies and inter- and intragroup processes.

<p>This study explored the use of code-switching in Biology classes at high school level, how it is used in the teaching and learning situation and its effect on the learners' performance in the subject. Grade 11 was chosen as it precedes the last year at high school.</p>

M.Com. (Business Management) / Please refer to full text to view abstract

Thesis (M.A. (African Languages)) --University of Limpopo, 2014

This study investigated the relationship between masculinity, cultural worldviews, and societal risk perceptions in a sample of school-going boys between the ages of 17 and 18 years old. The main objective was to examine the nature of the relationship between these variables of interest with the purpose of gaining insight into the type of societal risks that are of most concern and those risks that are rejected by males conforming to traditional masculine norms. Furthermore, this study compared the pattern of societal risk perceptions held by males conforming to the traditional masculinity type with the risk perceptions of males adhering to the accommodating and progressive masculinity types. This study also attempted to identify the type of cultural worldviews that were held by individuals adhering to traditional masculine norms and values. One hundred and fifty seven adolescent boys participated in the study and were given two questionnaires and two psychometric scales to complete. The findings of this study showed that males embracing traditional masculine norms and values were more likely to endorse hierarchical and individualist worldviews and to be less concerned about a variety of societal risks and the impact these posed for the South African public. In contrast, participants conforming to progressive masculine norms were more likely to be risk sensitive, showing heightened concern for the negative impact of a number of societal risks on the South African public. In accordance with cultural theory of risk, the risk ideologies upheld by each of the masculinity types were found to be functional in the sense that they supported the core values and agenda of that masculinity type. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2009.