List of Titles

The role of upwelling in determining the composition, species distribution and genetic structure of intertidal communities in a time of climate change

- Lourenço, Carla Sofia Emídio Rodrigues

Authors: Lourenço, Carla Sofia Emídio Rodrigues
Date: 2018
Subjects: Upwelling (Oceanography) , Intertidal organisms -- Morocco -- Atlantic Coast , Intertidal organisms -- Canary Current -- Effect of water currents on , Intertidal animals -- Canary Current -- Effect of water currents on , Intertidal animals -- Morocco -- Atlantic Coas , Mytilus galloprovincialis -- Morocco -- Atlantic Coast , Mytilus galloprovincialis -- Canary Current -- Effect of water currents on , Intertidal ecology -- Canary Current , Sea surface microlayer -- Morocco -- Atlantic Coast
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/61614 , vital:28042
Description: Upwelling is an oceanographic process that strongly influences coastal species and the communities they belong to. In upwelling areas, colder, denser, nutrient-rich subsurface waters are transported to the nearshore surface, replacing warmer superficial waters that are advected offshore. Such effects influence the composition and dynamics of coastal communities, for example by affecting species abundance, recruitment, dispersal and distribution. Upwelling areas are key model regions to study the responses of coastal species to climate change because they are characterized by cooler conditions and experience lower warming rates than adjacent regions. In particular, intertidal rocky shore species are ideal coastal sentinel organisms to study distributional changes driven by climate warming because they inhabit the interface between marine and terrestrial habitats and are exposed to extremely severe environmental conditions. In fact, sharp distributional shifts have been reported for multiple intertidal species as a response to ocean warming. Although some studies have investigated the role of upwelling in influencing abundance and distribution of intertidal species, little is known about its potential as refugia against climate warming and the degree to which upwelling shapes species genetic structure is yet not fully understood. The aim of this thesis is to understand the influence of the Canary Current upwelling system on intertidal community composition, including species distribution and the genetic structure of intertidal species under current climate change. To do this, I investigated community structure of intertidal assemblages along the Atlantic shores of Morocco and Western Sahara, performed large scale surveys on species distribution, evaluated species abundance and frequency of parasitism and examined species genetic patterns. I further coupled biological data with upwelling indices, sea surface temperatures (SST) and the rate of SST warming. I demonstrate that strong upwelling influences abundance and distribution of intertidal rocky shore species and that upwelling cells can act as refugia from climate change by ameliorating thermal conditions. Upwelling cells also conserve the genetic diversity of the marine macroalga Fucus guiryi, promoting intraspecific genetic diversity by preserving unique genetic lineages. However, no evidence was found that upwelling affects the genetic structure for either F. guiryi or the brown mussel Perna perna. Instead, the genetic patterns presented in this thesis seem to result from a combination of species’ life history traits, population size and habitat suitability. My results also suggest that upwelling intensity affects the frequency of endolithic parasitism on the Mediterranean mussel Mytilus galloprovincialis. In times of climate change, upwelling events provide suitable environmental conditions for species to counter act climatic change. As upwelling is project to intensify in the future, its influence on benthic intertidal species might be greater than previously anticipated.
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Date Issued: 2018

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Woody plant encroachment in arid and mesic South African savanna-grasslands: same picture, different story?

- Skowno, Andrew Luke

Authors: Skowno, Andrew Luke
Date: 2018
Subjects: Savanna ecology South Africa Eastern Cape , Remote sensing , Woody plants South Africa Eastern Cape , Grasslands South Africa Eastern Cape , Plant invasions South Africa Eastern Cape
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/62603 , vital:28212
Description: Woody plant encroachment in South Africa’s savanna-grasslands has been considered a rangeland management problem since the early 1900s. This phenomenon, which has been observed globally, is particularly important in Africa given the extent of tropical grassy biomes on the continent and their importance for rural livelihoods. In this study, local and regional scale approaches were used to investigate woody cover change in South Africa across the important savanna-grassland rainfall threshold of 650 mm mean annual precipitation (MAP). The aim was to test this threshold using remote sensing and demographic surveys in order to better understand the patterns, mechanisms and drivers of encroachment. Rates of encroachment and population demographics of Vachelia karroo were compared at arid and mesic savanna sites in the Eastern Cape, using time-series analysis of historical aerial photographs in conjunction with field surveys. Changes in the extent of woodland vs. grassland were then quantified at a national scale (1990-2013) by combining optical and synthetic aperture radar remote sensing data. This produced the first map of woodland- grassland shifts for South Africa and provided the basis for a spatially explicit investigation of the key drivers of change. The local studies revealed higher rates of encroachment at mesic sites than at arid sites, with a correlation between drought and rate of encroachment at the arid site. Vachelia karroo seedlings and stunted saplings were more prevalent at mesic sites than at arid sites and the growth form of adult trees differed significantly between sites. The national remote sensing investigation showed that woodland replaced grassland in over 5% of South Africa’s savanna- grasslands between 1990 and 2014, at rates consistent with other global and regional studies. Spatially explicit models showed a pattern of incremental expansion of woodland along a ‘tree front’ and complex relationships between woodland increase and fire, rainfall, terrain ruggedness and temperature. Overall, the local and regional scale findings of this work highlight the importance of the savanna rainfall threshold (~650 mm MAP) and the presence / absence of fire in understanding savanna dynamics and woody cover change in the context of global drivers such as elevated atmospheric CO2.
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Date Issued: 2018

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Malume’s bones

- Mokhele, Sizakele

Authors: Mokhele, Sizakele
Date: 2018
Subjects: Creative writing (Higher education) -- South Africa , South African poetry (English) -- 21st century
Language: English
Type: text , Thesis , Masters , MA
Identifier: http://hdl.handle.net/10962/63132 , vital:28366
Description: My poetry is about real stories: poverty, love, politics, past pains and healing. I try to follow the example of Amiri Baraka who says his poetry is whatever he thinks he is, that he makes poetry with “what can be saved out the garbage of our lives”. My collection also preserves and embraces demotic language, which is also a part of who I am. I am influenced by Baraka’s and Ike Muila’s use of demotics, and the way that poets such as Antonio Jacinto, Costa Andrade and Mafika Gwala tackle political matters in a colourful and powerful way. I have also been inspired by ancient Chinese poets to explore love and eroticism, particularly how it plays out in the eyes of my people.
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Date Issued: 2018

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Chemical weathering on selected nunataks in western Dronning Maud Land, Antarctica

- Knox, Jenna Tracy

Authors: Knox, Jenna Tracy
Date: 2018
Subjects: Glacial climates -- Antarctica -- Queen Maud Land , Glaciology -- Antarctica -- Queen Maud Land , Chemical weathering -- Antarctica -- Queen Maud Land , Atmospheric carbon dioxide -- Environmental aspects , Climatic changes -- Antarctica -- Queen Maud Land , Nunataks -- Antarctica -- Queen Maud Land
Language: English
Type: text , Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/61658 , vital:28046
Description: High latitude areas are sensitive to the impacts of climate change, and it is expected that the impact of greenhouse warming will be much higher in the polar regions than in any other climatic zones, with the most highly affected area being that of the Antarctic rim (Barsch, 1993). Weathering and pedogenic processes respond to variations in climate, with models predicting that chemical weathering may increase synchronously with global carbon dioxide levels increase, due to dissolution rates and the erosional impact of hydrological cycles in warming climates (Anderson & Anderson, 2010). As liquid water becomes more available in Antarctica the potential for chemical weathering, due to a less moisture-limited environment and increased temperatures, increases (Convey et al., 2009). Weathering processes are important for soil formation and the production of fine-grained material, with chemical weathering being an active constituent of this. Increased rates of soil formation are likely to occur, with global climate changes resulting in greater chemical weathering occurring in Antarctica. Opportunistic sampling was conducted during the Austral summer of 2016/2017, whereby rock, snow and meltwater samples were taken at various sites within the western portion of Dronning Maud Land of Antarctica. Rock samples were placed in resin, and cut with a diamond saw to create thin sections. Optical microscopy and scanning transmission electron microscopy (STEM) were used to analyse mineral weight percentage with depth. Twelve soil samples were dried and weighed, sieved and statistically represented according to particle size. Inductively coupled plasma mass spectrometry (ICP-MS) determined the geochemical analysis for 10 water and snow samples. Rock hardness was inferred through the use of an Equotip, with rebound values recorded for multiple rock faces and samples. Thermal regimes of rock temperature was further recorded using a FLIR infrared camera, and documented for each rock face over a 24 hour period at 2 hourly intervals. The products of increased chemical weathering were evident from particle size analysis; samples were very poorly sorted in nature, and undergo in situ weathering, whereby products were not removed by erosional processes. Weathering rinds were found to be siliceous and ferric, depending on parent lithology. Ferric ratios increased in wt.% from the substrate rock to the external surface, creating the red, iron rich crusts noted on the hand specimens. The observable chemical weathering was found adjacent to intrusions through Precambrian dolerites. Geochemical analysis revealed thin, carbonaceous features, with impurity-rich layers, characteristic of speleothem formation. Carbonaceous layers did not follow underlying substrate features, rather deposited at the external surface, upon which, further precipitation growth could occur, creating karst features. Extensive gypsum coatings (>2mm) under BSE imagery were identified, with the abundance of gypsum salts (below surface level) and rock coatings indicating active sulphuric acid weathering, in western Dronning Maud Land, Antarctica. Were mechanical processes faster than chemical, weathering rinds and solution features on silicate rocks would be uncommon in the Antarctic, periglacial landscape. However, this is not the case as the existence of these landforms implies that chemical weathering may occur faster than mechanical weathering processes (Pope et al., 1995). In a changing world, one needs to monitor these processes at a micro-scale in order to fully understand how periglacial environments react to global climatic changes, and the subsequent impacts on these sensitive environments.
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Date Issued: 2018

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The rupture in the Rainbow: an exploration of Joburg Pride’s fragmentation, 1990 to 2013

- McLean, Nyx Nicolene Cindy

Authors: McLean, Nyx Nicolene Cindy
Date: 2018
Subjects: Gay pride celebrations -- South Africa -- Johannesburg , Sexual minorities -- South Africa , Sexual minorities -- Crimes against -- South Africa , Hate crimes -- South Africa , Group identity -- South Africa -- Johannesburg , Identity politics -- South Africa -- Johannesburg , Racism -- South Africa , One in Nine Campaign
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/63822 , vital:28492
Description: In 2012 Joburg Pride was disrupted by the One in Nine Campaign who asked for a moment of silence to honour the lives of victims of hate crimes1 and violence. This interruption of the parade was met with violence from Joburg Pride organisers, marshals and participants, who explicitly told the campaign’s activists that they “had no right to be at the parade.” The activists were predominantly black lesbians and gender non-conforming people. This response suggested that there was no place within Joburg Pride for honouring and mourning the lives of LGBTIAQ people of colour that had been lost to hate crimes. In addition to the call for one minute of silence, the One in Nine Campaign argued that Joburg Pride had become depoliticised as a result of its increased commercialisation. This study is motivated by a need to understand this rupture that occurred in 2012, and to situate it within the history of the LGBTIAQ movement in South Africa. In particular, it investigates the argument made by the One in Nine Campaign that Joburg Pride had become depoliticised and commercialised. The tensions that were facilitated by the 2012 clash and the subsequent formation of alternative Pride events in 2013 are interesting in light of current conversations circulating in broader South African discourse around what it means to be a South African citizen. The study applies a poststructuralist, anti-racist queer feminist lens informed by queer theory, critical theory, critical race theory, and whiteness studies to the historical and current fractures within Joburg Pride. The study analyses Exit newspaper articles from 1990 to 2013, alongside interviews with key stakeholders involved in the 2012 clash. The analysis, informed by both thematic and discursive approaches, interrogates the following themes: depoliticisation, commercialisation, “community”, assimilation, whiteness, racism, rainbowism and rainbow-washing. In this thesis I argue that the commercial interests and apolitical stance of predominantly white Joburg Pride organisers came to exclude LGBTIAQ people of colour’s experiences, at a time when political organising around hate crimes was most necessary. The analysis further highlights a politics of assimilation rooted in rights-based discourse informed by the Rainbow Nation rhetoric of post-apartheid South Africa. Further, this study problematises the notion of “community”, and discusses its strategic use in assimilationist politics within the LGBTIAQ “community”. This study shows that the rupture in the rainbow that occurred at Joburg Pride 2012 was constituted by multiple ruptures that exist in South African society. The issues explored in this thesis are therefore not only useful for constructing more inclusive spaces for LGBTIAQ people, but also for the nation building project of South Africa.
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Date Issued: 2018

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Quantification of water resources uncertainties in two sub-basins of the Limpopo River basin

- Oosthuizen, Nadia

Authors: Oosthuizen, Nadia
Date: 2018
Subjects: Hydrologic models -- Limpopo River Watershed , Water-supply -- Limpopo River Watershed , Water-supply -- Management , Sustainable development , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Reservoirs -- Limpopo River Watershed
Language: English
Type: text , Thesis , Masters , MSc
Identifier: http://hdl.handle.net/10962/63267 , vital:28388
Description: The demand for water is rapidly growing, placing more strain on access to the resources and subsequently its management. For sustainable management, there is a need to accurately quantify the available water resources. Unfortunately, the data required for such assessments are frequently far from sufficient in terms of availability and quality, especially in southern Africa. In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. Such data is however, often inadequate in many sub-basins necessitating the incorporation of the uncertainty related to the estimation process. Model parameter estimation and input data are significant sources of uncertainty that should be quantified. Also, in southern Africa water use data are unreliable because available databases consist of licensed information and actual use is generally unknown. In this study, the water resources of two sub-basins of the Limpopo River basin – the Mogalakwena in South Africa and the Shashe shared between Botswana and Zimbabwe – are estimated. The study assessed how uncertainties in the Pitman model parameterisation and input water use data affect the estimation of surface water resources of the selected sub-basins. Farm reservoirs and irrigated areas data from various sources were collected and used to run the Pitman model. Results indicate that the total model output uncertainty is higher for the Shashe sub-basin which is more data scarce than the Mogalakwena sub-basin. The study illustrates the importance of including uncertainty in the water resources assessment process to provide baseline data for decision making in resource management and planning. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 22.6 Mm3 and 24.7 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased to between 22.2 Mm3 and 25.0 Mm3 when anthropogenic water use data such as small farm and large reservoirs and irrigation were included. The flows generated for Shashe was between 11.7 Mm3 and 14.5 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The predictive uncertainty of the model changed to 11.7 Mm3 and 17.7 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.
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Date Issued: 2018

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A social realist study of employability development in engineering education

- Nudelman, Gabrielle Reeve

Authors: Nudelman, Gabrielle Reeve
Date: 2018
Subjects: Critical realism , Electrical engineering -- Study and teaching (Higher) -- South Africa -- Cape Town , Employability , Career education -- South Africa -- Cape Town , School-to-work transition -- South Africa -- Cape Town
Language: English
Type: thesis , text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/62884 , vital:28307
Description: This qualitative case study of a course pairing offered to final-year electrical engineering students at the University of Cape Town in 2015 was undertaken in order to better understand the ways in which participation in undergraduate courses can prepare engineering students for the workplace. The course pairing consisted of New Venture Planning and Professional Communication Studies. While the former aimed to expose students to the knowledge relating to starting a new business, the latter focused on teaching students how to create written and oral texts to support such an endeavour. Using Roy Bhaskar’s critical realism as a theoretical underlabourer, the study develops understandings regarding the generative mechanisms at work during the two courses. In support of this, the study posits an understanding of employability that moves beyond the acquisition of discrete workplace skills. Rather, employability is conceptualised as discursive transformation, with students being deemed “work-ready” when they develop discursive identities as engineers. Data generation took place by means of focus group and individual interviews, ethnographic observation and documentary research. Margaret Archer’s social realist tools – in particular, analytical dualism and the morphogenetic framework were used to trace the students’ transformations over the course pairing. It was argued that those students who developed discursive identities of engineers were those who, in Archer’s terms, emerged as social actors at the end of the course pairing. Two characteristics of the courses were found to enable this transformation: those parts that promoted deepened understanding of what the role of “engineer” entailed and the parts that provided spaces for students to develop their own personal identities. The findings of the study indicated that discursive identities as engineers were more likely to be developed through the group work and spaces for reflection engendered by the courses than as a result of the formal curriculum. The implications of the research are that, while a focus on employability in engineering education is valid and productive, this needs to be supported by opportunities for authentic learning experiences which afford students the opportunity to engage in learning that promotes real-life application of knowledge. , Thesis (PhD)--Rhodes University, Faculty of Education, Education, 2018
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Date Issued: 2018

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