Crop fields abandonment: assessing the dynamics of degradation in relation to leverage points for sustainable land management in the Macubeni catchment, South Africa
- Authors: Sibiya, Silindile
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422470 , vital:71945
- Description: Soil erosion is a major global environmental problem and a pervasive forms of land degradation that threatens land productivity and food and water security. Some of the biggest sources of sediment in catchments are previously cultivated lands. Regardless of this factor, the abandonment of cultivated fields is not well-researched. Sustainable land management (SLM) interventions can play a significant role in mitigating and halting land degradation. This study investigated the dynamics of degradation exhibited by crop fields and the potential impacts of SLM interventions, using a leverage points framework and a case study in the Macubeni catchment of South Africa. The research answers three questions: (1) What is the relationship between the usage status of crop fields and degradation in Macubeni? (2) What are the drivers of crop field abandonment and how do they interact in the system? (3) Can proposed sustainable land management interventions tackle the dynamics of land abandonment, and associated degradation, at the root cause level? An empirical-analytical approach using a four step multi-method process was followed, in which crop fields were mapped using ArcGIS tools, literature was reviewed alongside stakeholder engagements, qualitative systems mapping modelling was undertaken, and a Multi-Criteria Analysis (MCA) with leverage points hierarchy was used to integrate all the steps together. The results revealed that the various drivers of crop field abandonment include natural environmental factors, socio-economic and social factors. 47.41% of the total crop fields in Macubeni were classified as highly degraded, and abandoned fields covered 37.47%. The statistical Chi-Square Test also confirmed that there is a significant relationship between the usage status and degradation level in crop fields. The SLM interventions assessed in the study have the potential to tackle the dynamics of land abandonment at a root cause level, however, there is a need to first shift the community’s mental models to address the existing sources of change resistance that are hindering successful implementation. Furthermore, the innovative multi-method approach applied in this study can further provide a holistic, dynamic, and integrated decision-support to land conservation and rehabilitation projects in similar settings across South Africa and other developing countries as opposed to the more traditional one-dimensional approaches. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-29
Factors influencing the number of non-timber forest product species used at the individual, household and village levels in Vhembe, Limpopo Province, South Africa
- Authors: Mulaudzi, Takalani Rachel
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422481 , vital:71946
- Description: Non-Timber Forest Products (NTFPs) are wild biological resources obtained from natural landscapes, agricultural systems, and rural and urban regions for a variety of uses. NTFPs contribute significantly to livelihoods and living standards by offering a variety of socioeconomic benefits such as food, health, income generation, and safety nets. These multiple benefits are provided by a wide diversity of plant, animal and fungal species in different settings. However, the precise number of NTFP species used depends on the scale of assessment, namely use by individuals, by households and by villages. Consequently, it is difficult to compare numbers of species used between studies because of the differing scales. As a result, the objective of this study was to determine the number of NTFP species used at three different scales and how each is correlated with appropriate scale-dependent contextual variables. This objective was met by sampling individuals and whole households in five villages in the Vhembe District in Limpopo Province, South Africa. Twenty households were randomly selected in each village, providing a total sample of 100 households and 179 individuals in those households. In each household, every adult member was interviewed individually about the NTFPs that they used or knew. The major questions covered the NTFP species used, the respondents' socioeconomic level, the NTFP species used previously, and if the number of NTFP species are changing in the landscape. Data were reported per individual as well as per household and per village. The household level was derived by adding the responses of all the adults in each household but excluding duplicates. The same approach was used at the village scale, namely, the data across the 20 households were pooled, and duplicates were omitted. Patterns of NTFP use were examined by type of NTFP, and analysis using standard statistical tests, along with a Principal Components Analysis and a multivariate Detrended Correspondence Analysis of the NTFP species composition across villages. A total of 275 species of NTFPs were mentioned across the entire sample, including 81 species of firewood, 48 species of edible insects, 43 species of wild vegetables, 40 species of edible fruits, 38 species of wood utensils, 28 species of medicinal plants, 23 species of thatch grass, 19 species of poles, 19 species of wood for carvings, nine species of reeds, eight species of mushroom, and eight species of fodder. Of these species, some species had more than one use. Approximately 90% of the species used by the respondents were native species. Wild vegetables (e.g., Corchorus olitorius, Amaranthus capensis, Bidens pilosa), firewood (e.g., Colophospermum mopane, Parinari curatellifolia, Combretum hereroense), wild fruit (e.g., Landolphia kirkii, Vangueria infausta), and edible insects (e.g., Imbrasia belina, Macrotermes michaelseni, Encosternum delegorguei) were the most often used NTFPs by communities in the Vhembe area. Most of the households relied on NTFPs for subsistence. At the scale of an individual, the mean number of NTFP species used was 26.8±12.6 across the five villages. When considering a household, the mean number was 36.1±10.7 species. When aggregated across the 20 households per village, the mean number per village was 105.2±34.1 species. The species accumulation curve showed that 20 households per village were reasonably representative for four of the five villages. The results from the principal component analysis (PCA) and correlation analysis revealed that age, education, and employment status were significantly associated with the number of species used by individuals, whereas gender showed no clear correlation. At the household scale, household size was positively related with the number of species used, but income level and income source were not. At the village scale, attributes such as proximity to a town, settlement type, vegetation type, and distance to a nearby savanna all had some influence on the number of NTFP species listed. Most of the respondents felt that the number of species used had increased over the last 10–15 years, although some stated the opposite. Increases were attributed by traditional councils bans, the establishment of protected areas, and restoration. Activities eroding the number of NTFP species were identified as clear felling for farming, climate change, and over-harvesting. This study suggests that communities must be made more aware of the overharvesting of NTFP species in the savanna to avoid biodiversity loss. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-29
The influence of immuno-contraception on the ecology of African savanna elephants (Loxodonta africana) in a small game reserve in the Eastern Cape, South Africa
- Authors: Fowler, Natalie
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422269 , vital:71926
- Description: African savanna elephants (Loxodonta africana) can alter the vegetation structure on a landscape which has both positive and negative consequences for biodiversity. This ecological role can be dependent on the density of elephants in a given area and how the area is transformed. Elephants are currently listed as an endangered species on the International Union for Conservation of Nature (IUCN) global red list. Despite this endangered status, strong conservation efforts in southern Africa have increased elephant numbers in protected areas. In South Africa, many of these protected areas are small (<1000 km2) and fenced. Thus, without the freedom to roam over large areas, elephant impacts on vegetation and other ecosystem processes may be exacerbated. Increased growth rates and higher population densities, have prompted wildlife managers to explore several population-level management techniques to slow elephant growth rates in small, protected areas. One such technique is the use of immuno-contraception. My study focused on three datasets (Pre, During and Post porcine zona pellucida (PZP) treatments) of one elephant population over an 18-year period in a small game reserve in the Eastern Cape, South Africa. The first aim of my study was to compare the female demography and reproductive parameters of treated (with PZP) and non-treated females (no PZP). I predicted that the population growth would decrease as more elephant cows were contracepted as well as them having longer inter-calving intervals than non-treated cows. Further, I predicted that there would be a skewed sex ratio of male calves born to treated cows. Lastly, I predicted that fertility rates would be lower in treated cows than in non-treated cows. I calculated the annual population growth rates, inter-calving intervals, sex ratios, age at first calving, fecundity rates and fertility rates of all breeding cows. Population growth rates were similar to other managed populations although, compared to a relatively untouched elephant population, annual growth rates in my study site were high. The inter-calving intervals and age at first birth were low compared to other African protected areas which were most likely influenced by the use of PZP, rainfall and a lack of density dependence. Treated cows did not have longer inter-calving intervals compared to non-treated cows nor was there a male biased sex ratio of the offspring of treated cows. The second aim was to assess the spatial ecology of this elephant population and how it may be influenced by immuno-contraception. I predicted that the use of PZP would increase the elephant herd’s core range as there were fewer reproducing cows. I also predicted that PZP would alter the elephant’s habitat use making them less selective in terms of the vegetation types they selected. I compared the home ranges of the elephant population among the three treatments (Pre PZP, During PZP and Post PZP treatment). Home ranges were larger when elephants were treated with PZP compared to the Pre and Post treatments. The herd utilized most of the reserve during the use of PZP whereas prior to contraception, their space use was mostly concentrated on the eastern side of the reserve. Additionally, the vegetation utilization was inconsistent across the differing timeframes, specifically between pre PZP and during PZP. Prior to the use of PZP, the elephant herd utilized the old lands and riverine thicket the most whereas during the use of PZP, the grasslands and karroid habitats were used the most. The most likely influence of the changes in home ranges and vegetation utilization were rainfall, the use of PZP and resource availability. My results suggest that the use of PZP is essential for controlling elephant population numbers. However, there may be some long-term effects (e.g., behavioural changes) of the use of PZP in elephant populations in small game reserves. Thus, I recommend continued monitoring of all aspects of elephant ecology on reserves where PZP is used as a contraceptive technique. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-03-29
Rapid Synthesis of Thiol-Co-Capped CdTe/CdSe/ZnSe Multi-Core-Shell QDs and Their Encapsulation in Liposomes and Chitosan Nanoparticles; Comparative Bio-compatibility Studies Using Hela and Vero Cells
- Authors: Daramola, Olamide Abiodun
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422617 , vital:71962 , DOI 10.21504/10962/422617
- Description: The common method that has been used to reduce the toxicity posed to living cells by CdTe Quantum Dots (QDs) is through the synthesis of CdTe multi-core-shells nanoparticles. In this process, the surface of CdTe QDs is usually coated by less toxic ZnS or ZnSe shells. This heterostructure compound does not only reduce the toxicity of CdTe QDs but can also be used in applications such as deep tissue imaging. The heterostructures can be in numerous forms such as CdTe/CdSe/ZnSe or CdTe/CdSe/ZnS or CdTe/CdS/ZnS multi-core-shell QDs. However, the drawbacks attributed to the fabrication of these compounds is long synthesis times (6- 24 h) in achieving the highest wavelength emission maxima. Others are the use of toxic reagents and poor reproducibility of synthesized materials. An additional problem is that the ZnSe or ZnS coating is insufficient to completely protect the highly toxic Cd metal from escaping into immediate solution. This limits their use in biochemistry and with living systems. Liposomes and biopolymers such as chitosan are known to be environmentally friendly compounds that have been used in various studies as delivery systems for QDs and model drugs for drug delivery applications. They are generally non-toxic and highly bio-compatible. In this study, the rapid synthesis of thiol-co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with a maximum reaction time of 35 mins, gave reliable QDs with emission maxima at 625 nm. The multi-core-shell QDs were encapsulated in two different bio-compatible environments, namely liposome and chitosan nanoparticles (CNP) at 14 different formulations (F) for liposome and 12 different formulations for CNP. Cytotoxicity and florescence imaging studies using HeLa and Vero cells, were used to investigate the improved bio-compatibility. Various characterization techniques were used to elucidate the optical properties, morphology and physico-chemical properties of the QDs and nanocomposites. Two of the best formulations, QD-liposome vesicles (LVs)-F12 and QD-CNP-F9 (with chitosan), demonstrated high loading efficiencies of 42 ± 6 % and 59 ± 5 %, respectively. While the plain CdTe QDs showed high toxicity, some of the encapsulated materials, QD-LVs-F1 and F12, depicted no-toxicity against the cells (IC50 > 0.5 mg/ml). The QDs also retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus, indicating the successful internalization of the QDs in the cytosol. These results shows that encapsulation of CdTe multi-core-shell QDs in liposomes produce better bio-compatibility compared to multi-core-shell QDs and better than CNP coating. These particles therefore show good promise in cell-labelling, drug delivery studies. Their core-shell nanoparticles have also shown good behavior in enhancing the memory of a device which is based on some recent collaborated works. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-03-31
Enhancing the use of large-scale assessment data in South Africa: Multidimensional Item Response Theory
- Authors: Lahoud, Tamlyn Ann
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422389 , vital:71938
- Description: This research aims to enhance the use of large-scale assessment data in South Africa by evaluating assessment validity by means of multidimensional item response theory and its associated statistical techniques, which have been severely underutilised. Data from the 2014 administration of the grade 6 Mathematics annual national assessment was used in this study and all analyses were conducted using the mirt package in R. A two parameter logistic item response theory model was developed which indicated a clear alignment between the model parameters and difficulty specifications of the test. The test was found to favour learners within the central band on the ability scale. An exploratory five dimensional item response theory model was then developed to investigate the alignment with the test specifications as evidence for construct validity. Significant discrepancies between the factor structure and the specifications of the test were identified. Notably, the results suggest that some items measured an ability that was not purely mathematical, such as reading ability, which would distort the test’s representation of Mathematics ability, disadvantage learners with lower English literacy, and reduce the construct validity of the test. Further validity evidence was obtained by differential item functioning analyses which revealed that fourteen items function differently for learners from different provinces. Although possible reasons for the presence of differential item functioning among provinces were not discussed, its presence provided sufficient evidence against the validity of the test. In conclusion, multidimensional item response theory provided an effective and rigorous approach to establishing the validity of a large-scale assessment. To avoid the pitfalls of the annual national assessments, it is recommended that this multidimensional item and differential item functioning techniques are utilised for the development and evaluation of future national assessment instruments in South Africa. , Thesis (MSc) -- Faculty of Science, Statistics, 2023
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- Date Issued: 2023-03-29
Semantic segmentation of astronomical radio images: a computer vision approach
- Authors: Kupa, Ramadimetse Sydil
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422378 , vital:71937
- Description: The new generation of radio telescopes, such as the MeerKAT, ASKAP (Australian Square Kilometre Array Pathfinder) and the future Square Kilometre Array (SKA), are expected to produce vast amounts of data and images in the petabyte region. Therefore, the amount of incoming data at a specific point in time will overwhelm any current traditional data analysis method being deployed. Deep learning architectures have been applied in many fields, such as, in computer vision, machine vision, natural language processing, social network filtering, speech recognition, machine translation, bioinformatics, medical image analysis, and board game programs. They have produced results which are comparable to human expert performance. Hence, it is appealing to apply it to radio astronomy data. Image segmentation is one such area where deep learning techniques are prominent. The images from the new generation of telescopes have a high density of radio sources, making it difficult to classify the sources in the image. Identifying and segmenting sources from radio images is a pre-processing step that occurs before sources are put into different classes. There is thus a need for automatic segmentation of the sources from the images before they can be classified. This work uses the Unet architecture (originally developed for biomedical image segmentation) to segment radio sources from radio astronomical images with 99.8% accuracy. After segmenting the sources we use OpenCV tools to detect the sources on the mask images, then the detection is translated to the original image where borders are drawn around each detected source. This process automates and simplifies the pre-processing of images for classification tools and any other post-processing tool that requires a specific source as an input. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
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- Date Issued: 2023-03-29
The link between behavioural plasticity and aerobic scope 1 phenotypes in predicting the survival of Chrysoblephus laticeps 2 under climate variability
- Authors: Bailey, Lauren Ashleigh
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422606 , vital:71961 , DOI 10.21504/10962/422606
- Description: Thermal variability in the marine environment is likely to have a considerable effect on fishes as it impacts physiological performance and vital (i.e metabolism, foraging and swimming style) and non-vital (i.e. reproductive fitness) energetic processes. When fish are subjected to thermal stress, they may primarily respond by changing their behaviour. Species that have broad phenotypic behavioural plasticity (i.e. defined as the ability to adjust behavioural activity in presiding environmental conditions in order to remain within their optimal thermal range) may have a competitive advantage. Fish behavioural plasticity may take many forms. Some species may seek out thermal refugia by changing their phenology or distribution, while others alter the timing of their seasonal and spawning migrations in response to a changing environment. Although fishes can use behavioural changes to cope with climate change impacts, there does appear to be variability in the behavioural responses within species. However, if alterations in behaviour are insufficient to ensure that the individual remains within their optimal thermal range, physiological acclimation (i.e. defined as the process in which an organism adjusts to prevailing conditions by broadening their thermal performance curve so that their performance is maximized in the new thermal environment) may be required. Therefore, there is a critical link between the behaviour and thermal physiology of fishes, particularly in a world where they are facing increasing thermal stress. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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- Date Issued: 2023-03-29
A native weevil and an exotic planthopper: investigating potential biological control agents for nymphaea mexicana zuccarini (nymphaeaceae) and its hybrids in South Africa
- Authors: Reid, Megan Kim
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422554 , vital:71957 , DOI 10.21504/10962/422554
- Description: Nymphaea mexicana Zuccarini (Nymphaeaceae) is an invasive plant originating from southern USA and Mexico that has become problematic in South Africa, invading several water bodies around the country. Manual removal of this plant is very labour intensive and is not cost efficient or effective for long term control, while the use of herbicides is damaging to the environment and expensive. Consequently, this plant is a desirable candidate for biological control, which takes advantage of enemy release of the target weed and aims to re-establish population suppression induced by host specific natural enemies. Initiating biological control requires that several steps are followed to maximise the success of the programme, and the first few of these, including overseas surveys in the native range of the plant, have already been completed. This thesis aimed to continue biological control research for this species to take further steps at effectively managing the plant. Firstly, pre-release surveys in the invaded range are necessary to: determine what factors (including enemy release) contribute to the invasiveness of the target weed; establish a baseline of information to allow for comparison after biological control agents have been released; and identify any insect herbivores that may already be present in the country. The pre-release surveys conducted in this study revealed useful information about N. mexicana invasions in South Africa and provided evidence that enemy release is applicable to this case. However, these studies determined that a native weevil, Bagous longulus Gyllenhal (Coleoptera: Curculionidae), has expanded its host range to include the exotic N. mexicana at three sites, and may thus have potential for management of the species through augmentative releases. The invasion of N. mexicana in South Africa is further complicated by the presence of several Nymphaea hybrids originating from a complex history of horticultural trade. Although previous research has shown that several hybrid groups are present in South Africa, their parentage is not known. As biological control requires the use of host specific insects adapted to overcome the unique chemical and morphological defences utilised by plant species, hybrids are notoriously difficult to manage because they possess intermediate characters inherited from parent species to which natural enemies may not have adapted. Although biological control of hybrids is challenging, other case studies have demonstrated that it is possible to find suitable agents, but the chances of success are increased if putative parents of the hybrids are known so that they can be surveyed for natural enemies. Further molecular studies including possible parents of the Nymphaea hybrids in South Africa were thus carried out in this thesis to focus future surveying efforts. Two main hybrid groups were identified with genetic similarity to two tested putative Nymphaea parents, and this will allow further investigations of these species to improve the chances of successfully managing these hybrid groups. Some of the tested hybrids showed genetic contributions from multiple groups, some of which were unidentified, so it is necessary to prioritise the most problematic hybrids for biological control. With more insight into the genetic makeup of the Nymphaea hybrids in South Africa, investigations into the host specificity of potential biological control agents can be conducted. The ideal biological control agent should have a broad enough host range to impact and survive on both N. mexicana and its hybrids, but without a host range so broad that it would pose risk to native South African species. Host specificity trials are thus necessary to determine the suitability of potential agents. The identification of B. longulus feeding on N. mexicana during pre-release surveys motivated further investigations to determine the natural distribution, field host range, and host specificity of B. longulus in experimentally controlled conditions. Further surveys were therefore conducted at native Nymphaea sites around South Africa in addition to host specificity trials using the native Nymphaea nouchali Burm. f. (Nymphaeaceae), two populations of N. mexicana, and a cultivated hybrid. Results from the surveys and host specificity tests suggest that B. longulus is widely distributed across South Africa, is specific to Nymphaea with no observed preference between N. mexicana and the native N. nouchali, and does not perform well on Nymphaea hybrids. Hence, B. longulus is promising for use in new association biological control through augmentative releases but is not suitable for management of hybrids. In addition to the potential use of the South African B. longulus, it is necessary to conduct host specificity trials for natural enemies from the native range of N. mexicana that were prioritised in previous studies. Megamelus toddi Beamer (Hemiptera: Delphacidae) is one such species that was imported into quarantined laboratory conditions from Florida, USA. Host specificity trials were conducted using the same test plants as described for the studies on B. longulus, in addition to multigeneration trials to determine how long M. toddi could survive on non-target host plants. As with the B. longulus studies, no statistically significant differences in preference were observed between N. mexicana and N. nouchali, but M. toddi could not complete development on the test hybrid, indicating that this species is also unsuitable for the management of Nymphaea hybrids. Despite suboptimal plant health, M. toddi completed development for three generations on the native N. nouchali. This lack of host specificity deems M. toddi unsafe for release in South Africa but highlights the importance of following predefined steps to develop a biological control programme. The concluding chapter of this thesis discusses the aforementioned findings in a broader context by considering the driving forces of plant invasions in general and specifically for N. mexicana in South Africa. Case studies are also consulted to provide insight into how to proceed with managing Nymphaea hybrids in South Africa, while the factors governing host specificity and host range expansion are also discussed and considered in the context of B. longulus and M. toddi. Finally, after a consideration of the limitations of these studies, recommendations are made to continue the development of biological control for N. mexicana in South Africa. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-03-31
Socio-historical analysis of organisational change: a case study of Zimbabwe Posts (Zimpost), 2010–2020
- Authors: Kambarami-Zengeni, Faith Chipo
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422518 , vital:71954 , DOI 10.21504/10962/422518
- Description: Postal organisations play an important role in the provision of basic communication services. In Zimbabwe, post offices have a large physical distribution network of over 240 post offices country-wide to make communication services accessible to the populace. However, e-substitution has threatened mail business significantly. Postal operators globally are experiencing declining mail volumes in the face of advanced information and communication technologies. The overall goal of this thesis was to undertake a socio-historical analysis of organisational change at ZimPost using Taylorism, Fordism and post-Fordism as broad ideal types to explain how industry evolves in different phases of capitalism. National politics and economics play an integral role in how Taylorism, Fordism and post-Fordism assumed at ZimPost. Studies on these broad organising types have mainly focused on private sector organisations. However, this thesis argues that these analytical paradigms are also valid in public sector organisations, but they will unfold differently given the context in which change is experienced. Using a qualitative approach, the study established that the 1980s and 1990s can best be described as the ‘golden years’ of postal services in Zimbabwe, characterised by mass production and mass consumption of postal products and services. At that time the Posts and Telecommunications Corporation enjoyed a monopoly of postal services in the country. The stable market share, competitive salaries for postal workers, increased unionisation and a fairly stable economy enabled a Fordist regime of accumulation to develop. The cycle broke down when the mode of regulation was weakened by national economic and political changes towards the late 1990s. PTC started to experience a decline in the consumption of postal products. The decline was also attributed to increased competition from smaller private courier operators that could provide specialised services to a market with changing needs. With increased competition, the advancement of information, and communication technologies, mail volumes dwindled. This period can best be described as the crisis of Fordism at ZimPost. In the year 2000, the government unbundled the posts and telecommunications corporation to create four companies including Zimbabwe Posts. This was perceived as one of the most radical organisational changes in the history of postal services in Zimbabwe. More organisational changes took place at ZimPost that can best be described as characteristics of post-Fordism. These changes were attempts by ZimPost to remain relevant in light of the economic, political and technological changes taking place in the country. The postal operator introduced customised products in the form of agency services, supported by increased use of information and communication technologies in the post office. Organisational changes at ZimPost were shaped mainly by the economic and political environment in which they took place. Organisational change is complex, changes do not follow a linear pattern, they are processual. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2022-10-14
Inadequate menstrual health management and human rights
- Authors: Hartley, Gemma-Maé
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422506 , vital:71953
- Description: Various human rights bodies have suggested that Inadequate Menstrual Health Management (MHM) could contribute to violations of human rights or, at the very least, is connected to the fulfilment of human rights. Despite recognition of this, there has not been thorough analysis of whether inadequate MHM is a violation of human rights, particularly in political discussions on the philosophy of human rights. Using a liberal cosmopolitan framework, this thesis attempts to bridge this gap and, ultimately, to argue that inadequate MHM constitutes a violation of human rights. This assertion brings with it various complications due to the heavily contested nature of human rights, their correlative duties, and the requirements for a lack of fulfilment to be considered a violation. I address each complication in turn. I argue that the traditional approach to human rights violations fails to consider the various ways that human rights are violated in our contemporary, globalised world. I suggest that structural violations of human rights should not be ruled out, particularly when we consider severe poverty and its by-products. Ultimately, the question of inadequate MHM is concerned with the content of human rights. If inadequate MHM were a violation, it would be a violation of women’s socio-economic rights. However, both group rights and socio-economic rights are contested. This thesis therefore justifies these rights. Group-differentiated rights are argued to be necessary for substantive equality. This is particularly the case when we consider the various risks women face simply because they are women. Women therefore need special protections and provisions for their human rights to be fulfilled. Socio-economic rights are necessary for the well-being and dignity of individuals everywhere. We can justify them even if they are costly, vague, and demanding on states, as critics argue they are. Therefore, if we can accept socio-economic rights and women’s rights, we can argue that inadequate MHM is a structural violation of human rights. Thinking about inadequate MHM in this way means we can respond to it with a level of urgency. This has the potential to improve the well-being, development, and dignity of women. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2023
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- Date Issued: 2022-10-14
Vulamasango Singene: sociological analysis of a rural social movement
- Authors: Kirchmann, Gail Lynne
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425132 , vital:72213
- Description: This dissertation tests the claim made by a large membership-based organisation that it is a social movement. The organisation, Vulamasango Singene (VS) operates across the rural areas of large parts of the Eastern Cape Province. It has, for twenty years, advocated for the re-opening of land restitution claims for a specific category of forced removal known as “betterment”. This study provides an analysis of an organisation that has yet to achieve its objective in spite of sufficient financial resources, logistical and strategic support, numeric strength and the legal clarity of its demand. The research is situated within the framework of social movement theory. The study examined the origins, institutional infrastructure, demographic make-up, activities and culture of VS. These were analysed against four components that are identified in the literature as key characteristics of a social movement. These are: (i) informal networks (as opposed to structured and managed engagements); (ii) a plurality of actors (as opposed to a homogenous grouping); (iii) mobilising around issues of conflict; and (iv) sharing common beliefs and demonstrating solidarity. Data were gathered through an archival study and field research. Semi-structured interviews were carried out with a sample of VS’s leadership, and staff of the non-governmental organisation in which VS originated, as well as expert informants in the land reform arena. The findings with respect to each of the criteria were: (i) VS’s structure was rigid and internal communication was largely formal. (ii) There was almost no demographic or political diversity within VS. (iii) VS had, in the past, mobilised around issues of conflict, but there had been no mobilisation for ten years. (iv) While there was some evidence of sharing common beliefs and demonstrating solidarity, this was limited. The conclusion reached was that VS is not a social movement. This does not imply that VS is not an important democratic or representative organisation. It does, however, provide a theoretical position from which VS, and other organisations, can direct further action. The study touched on the relationship between northern donors, local professional NGOs and grassroots organisations in South Africa. Interactions among these institutions impact on the way that organisations and social movements develop. Comparisons with other similar organisations were made and similarities and differences were highlighted. It was suggested that, because of the importance of the issue, further research in this regard is necessary. , Thesis (MA) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2023-10-13
Gender and the COVID-19 pandemic: exploring female vendors’ coping strategies in Lichtenburg during the lockdown
- Authors: Marumo, Mmaki Lesego
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425141 , vital:72214
- Description: The 2019 outbreak of the Coronavirus (COVID-19) in Wuhan, China, and its subsequent spread around the world caused uncertainty in the economy and other aspects of life. Most governments around the world took drastic measures to stop the spread of the virus and save lives. The most common of these measures were restrictions on people’s movement and trade. As a result, the world of work in South Africa changed dramatically, with over a million workers losing their jobs. That said, South Africa acutely felt the negative income effects of the COVID-19 pandemic. For those working in the informal economy, the five-week lockdown between March and May 2020 was a period of unprecedented insecurity and hunger, without work, income, or benefits. In light of the above, the study aimed to explore how female street vendors in Lichtenburg survived the impact of the COVID-19 national lockdown restrictions on trading activities between March 2020 and May 2020. The study sought to contribute to the understanding of the gendered impacts of the pandemic, particularly in relation to women in the informal economy, by examining the strategies and coping mechanisms adopted by them. Drawing on the sustainable livelihoods framework, this study examined the experiences of female street traders in Lichtenburg who were subjected to COVID-19 trade restrictions, assessed their coping strategies, and examined their support systems. The study was exploratory in nature, followed a qualitative approach, and adopted a case study design. Depending on the needs of the study, a purposive and convenience sampling techniques were chosen to address the research problem and questions. In order to explore women’s experiences on a specific topic, qualitative, semi-structured individual interviews were conducted with a sample of six female street vendors in Lichtenburg. The collected data were analysed using the thematic analysis technique. In this regard, the findings show that the perception upheld that the informal economy is an employment shock absorber during economic crises has been proven otherwise by the COVID-19 pandemic. The loss of profits led to a reduction in trading activities, which in turn increased the hardships of women street vendors. These vulnerability and hardships were made worse by the absence of government support structures since they were unable to navigate the procedures and had no one to turn to in times of need. As a result of the lack of formal channels of support and appropriate policy interventions, street vendors were particularly vulnerable to the financial consequences of the pandemic, resulting in an unpleasant reality of unsustainable livelihoods in the face of COVID-19. , Thesis (MA) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2023-10-13
The portrayal of migrants and liminality in Nadifa Mohamed’s Black Mamba Boy, The Orchard of Lost Souls and The Fortune Men
- Authors: Fühner, Melissa Ashleigh
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425056 , vital:72205
- Description: This thesis argues that the characters in Nadifa Mohamed’s oeuvre exhibit both vulnerability and agency and that their position in society oscillates as if between two poles, as they cross social and spatial boundaries. There is no existing scholarly research that focuses on child migrants in Mohamed’s texts specifically. Here, Black Mamba Boy, The Orchard of Lost Souls and The Fortune Men are analysed and compared with a central focus on the child migrant characters to examine her portrayal of conflict-induced migration and its impact on vulnerable communities. In Black Mamba Boy, Mohamed portrays Jama’s exilic journey where he leaves his homeland of Hargeisa and migrates across territorial borders in Northeast Africa to find his father. His quest brings him from Somaliland to Sudan as he walks through countries that are devastated by the war between the British and Italian colonial forces in the 1930s. As Jama attempts to cross the spatial distance between himself and his father he also treads the invisible line between life and death. Along his journey, Jama is exploited and abused by colonial troops and traumatised by the conflict he witnesses. Mohamed revisits her father’s precarious journey not to portray him as a victim but to make him “a hero, not the fighting or romantic kind but the real deal, the starved child who survives every sling and arrow that shameless fortune throws at them” (1). Thus, the text is an account of Jama’s strength as he miraculously survives the brutalities of war. Similarly, in The Orchard of Lost Souls, the child protagonist, Deqo, is a refugee with parents. She internally migrates through Hargeisa at the moment the region breaks out into the Somali Civil War. Deqo attempts to keep herself out of harm’s way as the town is destroyed by soldiers and rebel groups who have opened fire against civilians. As a female child migrant Deqo occupies a particularly vulnerable position as she navigates a space where gender-based violence is used as a method of war. Despite the dangers around her, Deqo actively seeks out safety and a path that will free her from the tightening grip of the war. The Fortune Men depicts Mahmood’s journey of migration as an adult. When he attempts to cross the border into Wales he is ostracised, abused, and dehumanised because of his difference. Jama and Deqo’s exilic journeys are compared to Mahmood’s unsuccessful migration and the children cross borders that adults cannot cross because they use their vulnerability to seek out opportunities and change their environment. This thesis is situated within the theoretical framework of transnational and diasporic literature with a specific focus on the impact of forced migration on child migrants. Through close engagement and comparison of the three primary ii texts mentioned, this thesis demonstrates the vulnerabilities and fluctuating agencies of characters to highlight their liminal positioning. , Thesis (MA) -- Faculty of Humanities, Literary Studies in English 2023
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- Date Issued: 2023-10-13
Phonological awareness skills of emergent bilingual Rumanyo-English learners
- Authors: Karupu, Erwina Mushinga
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425100 , vital:72210
- Description: This thesis is an account of a cross-sectional study which focused on investigating Phonological Awareness (PA) in emergent Rumanyo/English bilingual learners. PA and its contribution to reading fluency were investigated among 47 third grade learners with an average age of 9. 19, at a Namibian School, for which Rumanyo is the language of instruction and English, the first additional language. This cross-sectional study examines two levels of PA: Syllable awareness and phoneme awareness. Measures included three subtasks: identification, segmenting and deletion. Reading fluency was measured through oral reading fluency and silent reading. The findings suggest that learners’ levels of PA are still developing with learners performing better on syllable awareness measures than on phoneme awareness. Reading fluency results evince low levels of proficiency in Rumanyo and in English, an average level of proficiency was recorded. To determine the relationship between PA and reading fluency, a Correlation Matrix was run and followed later with a linear regression. The findings demonstrate that syllable awareness predicted reading fluency in Rumanyo, whilst phoneme awareness did not show any association and as such, the model fit did not show any relationship either. With regards to English, neither syllables nor phonemes were a predictor of reading fluency. The study further examined to what extent the phonology of Rumanyo transferred to English. , Thesis (MA) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
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- Date Issued: 2023-10-13
The mental health effects of social media on young adult South Africans in the COVID-19 pandemic: a thematic analysis of social media posts by Rhodes University students
- Authors: Jubase, Hlumelo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425122 , vital:72212
- Description: The COVID-19 pandemic in South Africa has been mainly discussed in terms of its socioeconomic effects and loss of life. While these are important, its mental health effects are given attention in this dissertation. In particular, this is explored through social media platforms, which saw increased usage as a result of regulations on movement to slow the Virus’ spread. This is explored during the hard lockdown (or ‘Alert Level 5’) and further, focuses on young adults, key users of social media platforms. Max Weber’s ‘social action theory’ and Michel de Certeau’s ‘theory of everyday life’ are drawn on, which help to analyse social relations from an individual level; and are used to explore the kinds of expressions made on a social media platform, and what can be said in mental health terms. These theoretical frameworks are applied to a university “Confessions” page, used mostly by young adults, where submissions were made anonymously. Findings indicate a great deal of trauma associated with the COVID-19 pandemic, but also evidence of the emergence of collective responsibility. They show the immense sacrifices made by participants for the opportunity of an education, and provide a window into the kinds of subjectivities experienced by South African young adults. Further, they show the importance of having more substantive mental health discussions in South Africa, a country familiar with traumatic experiences. , Thesis (MA) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2023-10-13
Empty adjectives and excessive intensifiers, or savvy discourse moves? A feminist critical discourse study of gender-based differences in the discourse of businesspeople on LinkedIn
- Authors: Schmauss, Lindsay Susannah
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425111 , vital:72211
- Description: This Feminist Critical Discourse Analysis (FCDA) examines the use of ‘empty’ adjectives and the equative intensifier so in discourse on LinkedIn, a social network service (SNS) for businesspeople and professionals. These linguistic features soften the impact of what is said in ways that can conform with politeness norms that one should not impose a point of view but can also be negatively construed as weak, uncertain and unclear. The North American sociolinguist, Robin Tolmach Lakoff (1973, 1975, 2004), first associated these linguistic markers with a feminine register in her seminal work, Language and Women’s Place, arguing that there is a social expectation that women talk like a lady and follow politeness conventions, while the speech of men is not similarly constrained. That women are socially conditioned to speak in ways that can undermine their clarity and assertiveness would present a particular dilemma in the business context, where clear, direct and confident communication is valued. This corpus-based study explores the dilemma in the context of LinkedIn where the linguistic behaviour of cisgender women indeed showed evidence of their struggle between conflicting impulses to talk like a lady and a desire to be taken seriously as businesspeople. While the examined features mainly appeared in the discourse of women, it was interesting to note men making use of ‘empty’ adjectives and so in communication contexts where the goal appeared to be relationship-building. As notions of business leadership are evolving to value organisational leadership more, this suggests that linguistic devices that have traditionally been associated more with the communal conversation of the stereotypical ‘woman’ appear to be gaining wider acceptance and relevance, although in domains orientated towards the “soft skill” of building relationships, rather than the “hard work” of business. While the value talking like a lady may be shifting, language that is the opposite of talking like a lady seems to remain the language of serious talk, and the kind of gender-based linguistic discrimination first theorised by Lakoff seems thus to persist, also in the sphere of business discourse. , Thesis (MA) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
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- Date Issued: 2023-10-13
Development of an evidence-based framework for the prevention and management of musculoskeletal disorders in South Africa
- Authors: De Bruyn, Elrico
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424232 , vital:72135
- Description: Background: Musculoskeletal Disorders (MSDs) are multi-causal soft tissue disorders that result in disability, discomfort, and pain. MSDs are prevalent in 21.5% of the world’s population and carry a great financial and personal burden to individuals, businesses and countries alike. The multi-casual nature of MSDs has resulted in a vast amount of literature being published on how to prevent and manage the disorders, to the extent that navigating through the literature to find effective and context-specific interventions has become time-consuming and difficult. This is the case in South Africa, where ergonomists have no guide or framework to navigate MSD literature, and context-specific literature is limited. Aims: This study aimed to assist ergonomists in South Africa navigate the MSD literature to identify and select appropriate MSD prevention and management interventions. To do so, three objectives of the study were identified: 1. Review MSD literature to identify effective MSD prevention and management interventions. 2. Create a framework to act as a guide for ergonomists to navigate MSD prevention and management studies. 3. To verify the suitability of the framework in the South African context. To achieve these objectives, the study took a two-phased approach. Phase 1: A scoping review of MSD literature was conducted to identify effective MSD prevention and management approaches. Sixteen (n=16) prevention strategies and fourteen (n=14) management strategies were identified. The information from the review was analysed and grouped into five hierarchical levels of interventions (“Law”, “Organisational Policies”, “Management Systems”, Workplace Interventions”, and “Individual”). This information, along with a conceptual model created for the navigation of the literature, was used to create a draft framework for musculoskeletal disorder prevention and management. It was concluded that although there were many effective MSD interventions, there was a lack of South African-specific literature. Phase 2: Interviews with five certified ergonomists working in the South African context were conducted to verify the framework’s suitability for a South African working environment. The interviews identified two MSD prevention and three MSD management themes as effective in South Africa. Both prevention themes (“training and education” and “workplace interventions”) were also mentioned to be part of the stakeholders’ ideal MSD prevention programme, further reinforcing their usefulness. The use of “workplace interventions” was also identified to be effective in MSD management, alongside interventions at the management level and the use of alternative tools and equipment. However, the lack of managerial buy-in was identified as a barrier to MSD prevention. Stakeholders also highlighted that job specification and work hardening was an MSD strategy missing from the framework that was effective in South Africa's MSD management. The use of surveillance practices was found to be ineffective in South Africa, with lots of resistance towards it from workers. Conclusion: The framework presented in Phase 1 identified many effective MSD interventions; however, only a few were found to be applicable to the South African working context during Phase 2. Future research should focus on identifying the success of different MSD interventions in South Africa with participation from the ergonomists involved in the implementation to create an even more suitable guide that matches the South African ergonomist’s needs. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
The effects of different shift patterns on nurses’ sleep-wake behaviours in selected, private healthcare facilities
- Authors: Bell, Emma Catherine
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424219 , vital:72134
- Description: Nurses are required to work shifts to provide 24-hour care, in which they complete physically and mentally demanding tasks. The length and type of shifts, particularly night shifts interfere with the natural sleep-wake behaviours, leading to extended wakefulness and overall reduced sleep, and increase the likelihood of sleepiness during subsequent shifts. This can in turn affected various cognitive processes such attention, vigilance and alertness, which are necessary during the care process. Sleepiness as a result of working shifts has also been associated with an increased risk accidents and error during the delivery of care. Given the unique demands and ways in which workplaces are structured, each context arranges its shifts in unique ways and thus, in order to determine how to manage the effects of shift work, it is important to understand how it affects self-reported fatigue and sleep, of, in this case, nurses. While there has been extensive research on this in the global north, to date, there has been limited research aimed at examining the effects of shift work on nurses’ sleep-wake behaviours and fatigue in the South African context. Therefore, the aim of this study is to characterise shift arrangements in selected private facilities and explore its effects on private healthcare nurses. This study adopted a cross-sectional, survey design using an amended version of Standard Shiftwork Index. The questionnaire included demographic and shift details and explored the impact of the shift systems on nurse sleep-wake behaviours and disturbances and fatigue and workload. It was distributed among shift working nurses registered with the South African Nursing Council across three selected, private, healthcare facilities in the Eastern Cape, over a two-month period. The responses were analysed with descriptive and inferential statistics, with open-ended questions analysed using a thematic analysis. A total of 51 nurses completed the survey. Nurses worked 12-hour shifts which included night shifts and day shifts with fixed start and end times. Over time was commonly reported and generally, nurses reported having very little control over their shift arrangements. Overall, nurses slept less than what they reported they needed on duty days, with nurses working both day and night shifts reporting to sleep less than the globally recommended required sleep. This was compensated for by longer sleep durations during days off. The data collection revealed that three different shift arrangements were in use, including permanent day shifts, permanent night shifts and rotating shift work including nights, with permanent night nurses working significantly more consecutive shifts (seven) than the other two shift types and having significantly more days off (seven) as well. While there were no significant differences in self-reported sleep across the three shift types, permanent night nurses were found to have the shortest sleep. During days off, rotating nurse reported significantly longer sleep times compared to day shift workers which may point to the need to catch up from sleep debt. Rotating nurses experienced the greater total disturbances to their sleep than permanent day and permanent night shift nurses. While not statistically significant, it may point to the fact that rotating shift workers could not obtain regularly timed sleep (due to having to change their schedules) compared to permanent day and night nurses. Workload (physical, emotional, mental and time pressure) did not differ between the shifts (day or night) or the shift types, but did reflect a heavier workload, possibly due to the data collection occurring during the 5th wave of the COVID 19 pandemic. This study highlights that nurses in private healthcare facilities are working extended hours which were associated with reduced total sleep, irrespective of the nature of the shift, with rotating shift nurses experiencing some degree of greater disturbances to their sleep. The number, duration speed and direction of the shifts of rotating nurses needs to be explored further, whilst also exploring the influence of individual factors on sleep-wake behaviours of nurses. It may be beneficial for the healthcare facilities to implement fatigue management strategies to mitigate the negative impacts of shift work, given the impact that this may impact the delivery of care. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
Evaluating the potential effects of microplastics at environmentally realistic concentrations in South African freshwater systems
- Authors: Mtintsilana, Zintle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424160 , vital:72129
- Description: Microplastic pollution is spatially broad, microplastics can be found in various habitats including freshwater systems. Microplastic exposure to aquatic organisms has been associated with several physical impacts on aquatic organisms from multiple trophic levels such as; increased immune response, a decrease in food intake, excessive loss of weight, reduced growth rate, reduced energy and adverse effects on successive generations. However, these significant effects of microplastics exposure have been observed mostly in studies that use concentrations of microplastics that exceed environmental concentrations. Therefore, there is an overall lack of research on the effects of microplastics on freshwater organisms using environmentally realistic concentrations, especially in the Southern Hemisphere. A series of toxicity tests were used to expose a range of taxa including Tilapia sparrmanii, Caridina nilotica, and Melanoides tuberculata to different environmentally realistic concentrations of microplastics of different polymers. The study results show that the environmentally realistic concentrations had no statistically significant effects on most of the chosen test organisms and selected study endpoints, except for T. sparrmanii microplastic particle egestion and growth in polyethylene exposures which produced significant results. Although this study showed that at environmentally realistic concentrations and 21 days of exposure, minute effects on the test taxa were detected, various studies have proven that with longer exposure to microplastics, significant effects on freshwater organisms can be detected. Additionally, studies using concentrations higher than the current environmental concentrations have recorded significant effects on organisms and therefore, with increasing concentrations in the environment, more significant effects may be observed. Therefore, plastic pollution in the environment should be reduced as microplastics are in continuous production and circulation, and microplastic concentrations in freshwater environments are predicted to increase. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
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- Date Issued: 2023-10-13
Macroplastics in the environment: are they suitable habitats for macroinvertebrates in riverine systems?
- Authors: Ali, Andrew Abagai
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424153 , vital:72128
- Description: Emerging pollutants, such as plastics are threat to freshwater ecosystems, and may negatively impact riverine systems. They can modify riverine habitats and affect aquatic organism distribution and composition. Knowledge of how macroplastics alter riverine habitat heterogeneity, and their effects on macroinvertebrate assemblage structure is sparse, especially in Africa. This study examines the effect of hydraulic biotopes on the colonisation, establishment and succession patterns of macroinvertebrates on macroplastic and natural substrates based on the taxonomic and trait-based approach. Four experimental sites from minimally impacted upper reaches of the Buffalo, Kat, Kowie, and Swartkops Rivers in the Eastern Cape of South Africa were selected for the deployment of plastic substrates. Plastics materials, including polyethylene terephthalate (PET) bottles and natural substrate composed of stone and vegetation, were used to formulate three substrate groups: Group 1: 100% natural substrates (NS), Group 2: 50% natural substrates and 50% plastic material (NP), and Group 3: 100% plastic materials (PD). These substrates were placed in litter bags of equal dimension (25 cm by 35 cm, with 2.5 cm mesh) and deployed randomly in three hydraulic biotopes (pools, riffles, runs) over a period of 180 days (October 2021 to April 2022). A total of 216 substrate bags, 54 bags per substrate were deployed per site in the four experimental sites. Twelve bags from each substrate group were retrieved at an interval of 30 days beginning on day 30 after deployment, and analysed for the establishment of macroinvertebrate communities. Based on composite hydraulic biotope data, Simpson index was significantly higher (P < 0.05) for macroinvertebrate assemblage structure on the 50% and 100% macroplastic substrate groups compared to natural substrates. With the exception of Tabanidae, Glossosomatidae, and Psephenidae, all macroinvertebrate taxa recorded showed non-significant positive correlations with all three substrate groups. However, Tabanidae, Glossosomatidae, and Psephenidae showed significant positive correlation with the 100% natural substrates, 50% plastic substrates and 100% plastic substrates, respectively. The parsimony analysis reveal that, within 30 days, all substrate groups underwent similar succession, with high abundance of pioneer taxa which increased on days 60 and 90, and then decreased from days 120 to 180. For the the pool biotope, Shannon and Simpson indices were significantly higher (P < 0.05) for the macroinvertabrates collected over the natural substates compared with those collected on the macroplastic substrate groups. However, in the riffle and run biotopes, all diversity indices were similar for all substrate groups and no statistically significant difference was observed. Statistically significant higher values for taxonomic richness, diversity, and evenness were found on day 30 to 90 for the riffle biotopes, and day 30 to 60 for the run biotopes. The run biotope presented temporal statistical significant variability in taxonomic composition with different macroinvertebrate communities recorded on days 30 and 60 compared with days 90 to 180. However, in pools and riffles, no temporal variation was observed in the taxonomic composition of macroinvertebrates on all three substrate groups. The trait-based fuzzy correspondence analysis revealed differential spatial-temporal distribution of macroinvertebrate traits on all three substrate group. The early colonisers i.e. day 30 – 60, were dominated by group of taxa characterised by medium (>10 – 20 mm) and large (20 > 40) body size, flat body, collector-gatherers, free-living, and predators. The late colonisers, collected mainly on day 150 and 180 were dominated by taxa with a preference for high flow velocity (0.3 - 0.6 m/s), permanent attachment, and filter-feeding mode. Traits such as oval and flat body shape, medium body size (>10 - 20 mm), skating and clinging/climbing mobility, temporal attachment, shredders, predators, prey, and plastron and spiracle respiration showed positive correlation with the 100% macroplastic substrates. Filter feeding, crawling, permanent attachment, a preference for fast velocity (0.3-0.6 m/s), and coarse particle organic matter were positively correlated with the 50% macroplastic substrates. Overall, the results provided critical insights on the impact of macroplastics on the assemblage structure of biological communities by acting as suitable habitats in stream ecosystems. The study elucidated the role of traits of aquatic organisms in mediating the colonisation of plastics substrates, providing insights into the impact of plastics proliferation on riverine ecosystem functioning. Furthermore, the finding provides a baseline insight into the influence of hydraulic biotopes on the colonisation and establishment of macroinvertebrates on macroplastic acting as artificial riverine habitat. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
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- Date Issued: 2023-10-13