Do submarine canyons influence the structure and diversity of benthic fish assemblages on the continental shelf edge?
- Authors: Nyawo, Mpilonhle Aura June-Rose
- Date: 2020
- Subjects: Submarine valleys , iSimangaliso Wetland Park (South Africa) , Biotic communities -- South Africa -- iSimangaliso Wetland Park , Groundfishes -- South Africa -- iSimangaliso Wetland Park , Marine ecology -- South Africa -- iSimangaliso Wetland Park
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167264 , vital:41462
- Description: Marine ecosystems play an important role in human welfare, such as providing food security and providing social, economic and environmental benefits to an increasing human population. However, due to the deleterious impact of overfishing as well as habitat degradation, pollution and climate change, many marine ecosystems and the substantial biodiversity they support, are under increasing threats. Submarine canyon ecosystems cut into the continental margin in all our oceans and are considered regions of enhanced diversity, abundance and biomass for many marine communities, including fish. In South Africa, the tropical Delagoa Ecoregion is characterised by numerous submarine canyons that are home to coelacanths Latimeria chalumnae, and a variety of commercially important line fish species. However, there is currently a lack of information on the ecological structure and functioning of these canyons, in relation to nearby non-canyon ecosystems. The aim of this thesis was to generate knowledge on the role of submarine canyons in influencing the benthic fish assemblage structure and diversity on the continental shelf and shelf edge within the high-latitude coral reef ecosystems in the tropical Delagoa Ecoregion of South Africa. First, a systematic literature review was conducted to examine the current knowledge on the role of submarine canyons on the benthic fish assemblages occurring on continental margins, as well as outline the trends in canyon research. For the fieldwork component of this thesis, baited remote underwater stereo-video systems were utilised to gather data. The first research chapter, chapter 3, investigated the effect of ecosystem and depth on the diversity and structure of benthic fish assemblages within iSimangaliso Wetland Park in the Delagoa Ecoregion. Data were collected in 2017 from Wright Canyon (canyon ecosystem) and adjacent slope ecosystems around the canyon (non-canyon ecosystem) at depths ranging between 70–240 m. The second research chapter, chapter 4, data were collected in 2018, from 60–100 m depths in three ubmarine canyons (Wright, Diepgat,Levens) and their adjacent habitat within iSimangaliso Wetland Park to investigate the diversity patterns and community structure of benthic fish and cons ider location as a factor. The systematic review showed that canyon research is still very much in its infancy, however more papers are expected to be published in the future. There were clear location associated biases detected, with more than 90% of the canyon research being concentrated in the Mediterranean Sea, while only one study was published from South Africa. Most of the reviewed literature focused on invertebrates, with benthic fish (including cartilaginous fish) being the second most studied taxa. A wide range of methods from both fishery- dependent and fishery-independent categories were used to gather the data of benthic fish from the canyons and adjacent areas. With over 8500 submarine canyons mapped globally, the number of submarine canyon research published and the detected location bias is of great concern. More studies are needed in order to understand the role of submarine canyons on adjacent slope habitats Overall, the results from the research chapters indicated that there were higher a bundances in the canyon ecosystem compared to the non-canyon ecosystem. In contrast, evenness and beta-diversity were higher in the non-canyon ecosystem. Relief, bottom type as well as depth played a major role in explaining the observed abundance and diversity patterns. Both evenness and beta-diversity decreased with increase in depth. The canyon and non-canyon also differed in terms of habitat structure. The canyon ecosystem was characterised by patched reef and reef habitats with high relief whereas the non-canyon ecosystem was characterised by flats and habitats, especially at shallower depths. Additionally, there were clear differences in terms of the fish community structure between the canyon and the non-canyon ecosystem. The heterogeneous and complex habitats of the canyon ecosystem were typified by species such as Epinephelus poecilonotus, Polysteganus coeruleopunctatus and Chrysoblephus puniceus in comparison to the less complex habitats outside the canyons that were preferred by species such as Lagocephalus sceleratus, and Rhinobatos leucospilus. The different locations sampled demonstrated that the canyon effect was not onsistent at all locations, with varying results detected in the different sample locations. This research demonstrates that clea r differences exists between the benthic fish assemblages associated with canyon and non-canyon ecosystems and provides important information on the role of submarine canyons in the iSimangaliso Wetland Park. From this thesis, it is clear that a ‘canyon effect’ exists in the continental shelf and shelf edge. The results suggested that heterogeneity of habitats was the most important environmental factor that differed between the canyon and non-canyon ecosystems and these differences in the habitat were driving the observed patterns. This thesis has provided a reference point, with regards to investigating the role and influence of these canyons on benthic fish assemblages occurring on the continental shelf edge. The information provided by this thesis can ultimately be used in other studies investigating benthic fish assemblages in other submarine canyons within iSimangaliso Wetland Park and the rest of South Africa./
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- Date Issued: 2020
Fluid characteristics in hydrothermal veins of the Twangiza-Namoya Gold Belt, South Kivu and Maniema Provinces, DRC
- Authors: Reid, Wesson Kyle
- Date: 2020
- Subjects: Gold ores -- Geology -- Kivu (Congo : Region) , Mineralogy -- Congo (Democratic Republic) , Hydrothermal deposits -- Congo (Democratic Republic) , Quartz -- Congo (Democratic Republic)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167314 , vital:41467
- Description: This study evaluates fluid variations in hydrothermal quartz veins from gold deposits in Kamiuga, Lugushwa and Namoya, located in the Twangiza-Namoya Gold Belt (TNGB) of the Kibara Belt in the eastern Democratic Republic of the Congo (DRC. Petrographic, fluid inclusion (FI) microthermometric observations and Raman spectroscopy provided qualitative and quantitative fluid composition data on the hydrothermal and magmatic fluids and their evolution during mineral precipitation. The formational fluids, based on genetically specific characteristics, were categorized into six distinct FI Types. Type 1 to 4 FIs are common in all TNGB fluids. Type 1 and 2 FIs are high salinity halite bearing FIs that indicate formation fluids that are predominantly metamorphic-sedimentary in source. CO2 vapour-bearing and the aqueous-saline CO2 liquid-bearing Type 3 FIs commonly contain CH4 and/or N2. Type 4 FIs are saline aqueous and commonly co-genetic with Type 1 and 2 FIs. Type 5 CO2-rich FIs contain either sulphide crystals, amorphous or crystalline carbon. Type 3 and 5 FIs indicate fluid sources rich in organic materials. Type 6 single aqueous-liquid phase FIs have no apour bubble, lacked a visible phase change on heating and were not thermometrically evaluated. The data indicated a high correlation between fluid composition and gold grades. High Au grade veins correlate with CO2 bearing Type 3 and 5 FIs -predominantly liquid-bearing CO2 fluids and quartz veins and fluids that contain increased organic material and sulphides. The polyphase quartz veins show highly variable homogenisation and formational temperatures exceeding 400°C. Formation conditions indicate high trapping temperatures in relation to the pressures at which fluids were captured. The high depth-temperature gradients are likely associated with mesothermal orogenic go ld deposition. Mineralisation is interpreted to have taken place as a result of mobilisation of fluids during the Pan African orogeny. Based on fluid petrography and microthermometry, gold mineralisation is most likely associated with secondary fluid influx from metamorphic sedimentary sourrces such as metapelites. The correlation between high gold grades and secondary fluids containing sulphides, high depth-temperature gradients, elevated CO2, CH4 and organic materials suggest black shales as a possible primary fluid and gold source. The development of variable and multiple fluid influx events and interactions with host rocks and imported materials resulted in complex polyphase quartz veins; the product of which created viable gold deposits throughout the TNGB. The six FI Types provides evidence of the diversity in the formation and evolution of gold deposits in the TNGB.
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- Date Issued: 2020
Reading William Blake and T.S. Eliot: contrary poets, progressive vision
- Authors: Rayneard, Max James Anthony
- Date: 2002
- Subjects: Blake, William, 1757-1827 -- Criticism and interpretation , Eliot, T. S. (Thomas Stearns), 1888-1965 -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2279 , http://hdl.handle.net/10962/d1007545 , Blake, William, 1757-1827 -- Criticism and interpretation , Eliot, T. S. (Thomas Stearns), 1888-1965 -- Criticism and interpretation
- Description: Many critics resort to explaining readers' experiences of poems like William Blake's Jerusalem and T.S. Eliot's Four Quartets in terms of "spirituality" or "religion". These experiences are broadly defined in this thesis as jouissance (after Roland Barthes' essay The Pleasure of the Text) or "experience qua experience". Critical attempts at the reduction of jouissance into abstract constructs serve merely as stopgap measures by which critics might avoid having to account for the limits of their own rational discourse. These poems, in particular, are deliberately structured to preserve the reader's experience of the poem from reduction to any particular meta-discursive construct, including "the spiritual". Through a broad application of Rezeption-Asthetik principles, this thesis demonstrates how the poems are structured to direct readers' faculties to engage with the hypothetical realm within which jouissance occurs, beyond the rationally abstractable. T.S. Eliot's poetic oeuvre appears to chart his growing confidence in non-rational, pre-critical faculties. Through "The Love Song of J. Alfred Prufrock", The Waste Land, and Four Quartets, Eliot's poetry becomes gradually less prescriptive of the terms to which the experience of his poetry might be reduced. In Four Quartets he finally entrusts readers with a great deal of responsibility for "co-creating" the poem's significance. Like T.S . Eliot, although more consistently throughout his oeuvre, William Blake is similarly concerned with the validation of the reader's subjective interpretative/creative faculties. Blake's Jerusalem is carefully structured on various intertwined levels to rouse and exercise in the reader what the poet calls the "All Glorious Imagination" (Keynes 1972: 679). The jouissance of Jerusalem or Four Quartets is located in the reader's efforts to co-create the significance of the poems. It is only during a direct engagement with this process, rather than in subsequent attempts to abstract it, that the "experience qua experience" may be understood.
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- Date Issued: 2002
The puzzle of domination in society : seeking solutions in the African context
- Authors: Madonko, Thokozile
- Date: 2006
- Subjects: Rosen, Michael. On voluntary servitude , Fanon, Frantz, 1925-1961 , Fanon, Frantz, 1925-1961 -- Political and social views , Biko, Steve, 1946-1977 , Ideology , Black people -- Race identity , Ideology -- Psychological aspects , Ideology -- Sociological aspects , Power (Social sciences) , Consciousness , Racism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2855 , http://hdl.handle.net/10962/d1007260 , Rosen, Michael. On voluntary servitude , Fanon, Frantz, 1925-1961 , Fanon, Frantz, 1925-1961 -- Political and social views , Biko, Steve, 1946-1977 , Ideology , Black people -- Race identity , Ideology -- Psychological aspects , Ideology -- Sociological aspects , Power (Social sciences) , Consciousness , Racism
- Description: The presence of human destitution, impoverishment and degradation in the midst of plenty has puzzled social thinkers for millennia. One of the oldest and grandest of theories: the theory of ideology attempts to provide an answer to the puzzle of domination in society. Michael Rosen, in his book On Voluntary Servitude (1996), argues that the solution provided by the theory of ideology is problematic. Furthermore, on the basis of his critique, Rosen argues that we should abandon the theory of ideology and consider alternatives to it. Even though many contemporary academics have turned away from the theory of ideology, because they view it as an imprisoning meta-theory, this study explores the possibility of there being a meta-theory that could help us to make sense of the world. Through an examination of Rosen's critique this thesis shows that Rosen is too quick in his dismissal of the theory of ideology because he fails to consider that a revised functionalist theory of ideology can be expanded to account for the mechanism(s) that ensure that, over time, the society in question acquires ideological consciousness to further its welfare. This thesis shows that Rosen is correct in his criticism of the theory of ideology's explanation of domination because the content, history and social effects of ideological consciousness cannot be fully explained in terms of their role in promoting or stabilising relations of domination. In light of Rosen's criticism the thesis shows that if one provides both an explanation of the psychological motivations of individuals and of the nature of the oppressive society in which they find themselves then what I call an integrated theory of ideology can be developed. In order to illustrate the importance of an integrated theory of ideology the study moves away from high-level theoretical abstraction to concrete social analyses, focusing on the work of Frantz Fanon and Steve Biko and their explanations of domination. The reason this study focuses on their work is because in their role as social scientists, Fanon and Biko provided a powerful critique of colonial, post-colonial and neo-colonial society. It will be argued that Fanon and Biko were able to provide a lasting critique of colonial reality because they offered their critique within the framework of such an integrated theory. Consequently, this study argues that, as Fanon and Biko's work illustrate, an integrated theory of ideology qua critical theory ought not to be abandoned because it is crucial for understanding and resisting forms of oppression that exist in the world today.
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- Date Issued: 2006