The synthesis, characterization, and application of peptide-capped magnetite nanoparticles for the targeting of cancer cells
- Authors: Hickson, Matthew Victor
- Date: 2019
- Subjects: Nanomedicine -- Research , Nanostructured materials Cancer -- Alternative treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40172 , vital:35965
- Description: In this study, a comparative analysis was performed upon three co-precipitation techniques for the synthesis of capped magnetite nanoparticles as to optimize the approach to the highest quality nanoparticles. Three techniques were applied whereby the capping agent either introduced before the stage of nanoparticle precipitation, simultaneously to the stage of precipitation, or after the stage of precipitation. The resultant nanoparticles were tested in terms of their size, dispersity, crystallinity, and magnetic characteristics. The three techniques gave nanoparticles of varying sizes and characteristics. Out of the three synthetic techniques, the post precipitation introduction method gave the highest quality nanoparticles in terms of size distribution, crystallinity and magnetic character. Three novel peptides were synthesized, incorporating amino acids to varying degrees. Structure was confirmed via IR and NMR spectroscopy. The peptides were studied potentiometrically to explore their acid nature and were explored computationally as to discern possible modes of interaction with the nanoparticles. These three peptides were further used in the capping of magnetite nanoparticles. For this set of nanoparticles, a higher synthesis temperature and larger iron content were used as to obtain larger nanoparticles. For the capping procedure, the post precipitation technique was used due to its previous positive results, once again yielding high quality nanoparticles with low size dispersity, high crystallinity, and high magnetic saturations. The nanoparticles were also seen to display positive zeta potentials, which are beneficial for cellular interactions. The peptides and peptide-capped nanoparticles were tested for biological activity against the healthy MCF-10A and cancerous MCF-7 cell lines. The MTT assay displayed increased proliferation for both the cell lines treated with the nanoparticles, while the peptide treatments decreased the MCF-10A cell lines proliferation and increased the MCF-7 proliferation. TEM analysis displayed nanoparticles in the cellular sections. An ICP-OES analysis on the cells showed that the capped nanoparticles of similar zeta potentials were seen to be taken up excessively by cells as compared to the uncapped. The nanoparticles of lower zeta potentials but higher L-glutamine content were taken up to a lesser degree.
- Full Text:
- Date Issued: 2019
- Authors: Hickson, Matthew Victor
- Date: 2019
- Subjects: Nanomedicine -- Research , Nanostructured materials Cancer -- Alternative treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40172 , vital:35965
- Description: In this study, a comparative analysis was performed upon three co-precipitation techniques for the synthesis of capped magnetite nanoparticles as to optimize the approach to the highest quality nanoparticles. Three techniques were applied whereby the capping agent either introduced before the stage of nanoparticle precipitation, simultaneously to the stage of precipitation, or after the stage of precipitation. The resultant nanoparticles were tested in terms of their size, dispersity, crystallinity, and magnetic characteristics. The three techniques gave nanoparticles of varying sizes and characteristics. Out of the three synthetic techniques, the post precipitation introduction method gave the highest quality nanoparticles in terms of size distribution, crystallinity and magnetic character. Three novel peptides were synthesized, incorporating amino acids to varying degrees. Structure was confirmed via IR and NMR spectroscopy. The peptides were studied potentiometrically to explore their acid nature and were explored computationally as to discern possible modes of interaction with the nanoparticles. These three peptides were further used in the capping of magnetite nanoparticles. For this set of nanoparticles, a higher synthesis temperature and larger iron content were used as to obtain larger nanoparticles. For the capping procedure, the post precipitation technique was used due to its previous positive results, once again yielding high quality nanoparticles with low size dispersity, high crystallinity, and high magnetic saturations. The nanoparticles were also seen to display positive zeta potentials, which are beneficial for cellular interactions. The peptides and peptide-capped nanoparticles were tested for biological activity against the healthy MCF-10A and cancerous MCF-7 cell lines. The MTT assay displayed increased proliferation for both the cell lines treated with the nanoparticles, while the peptide treatments decreased the MCF-10A cell lines proliferation and increased the MCF-7 proliferation. TEM analysis displayed nanoparticles in the cellular sections. An ICP-OES analysis on the cells showed that the capped nanoparticles of similar zeta potentials were seen to be taken up excessively by cells as compared to the uncapped. The nanoparticles of lower zeta potentials but higher L-glutamine content were taken up to a lesser degree.
- Full Text:
- Date Issued: 2019
The social sustainability of low-cost housing: the role of social capital and sense of place
- Authors: Williams-Bruinders, Leizel
- Date: 2019
- Subjects: Housing -- South Africa , City planning -- South Africa Cities and towns -- Research Urban geography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44390 , vital:37161
- Description: In the past twenty years we have seen the South African government deliver the largest number of houses in the world (NDHS, 2011). However, this great effort does not appeal to the principles that policies have set out in terms of equality. Along with the delivery of this high level of state funded housing, many of the RDP dwellers feel as though they have been marginalised and forced out of the area of opportunity, namely, the CBD and the northern suburbs (Huchzermeyer, 2003). Many researchers believe that the South African housing delivery pattern resembles that of apartheid segregationist planning, which exacerbated the social inequalities in the country (Huchzermeyer, 2003; Donaldson, 2001; Harrison et al., 2003). To gain an in-depth understanding of the lived experiences of residents of a low-cost housing settlement, an interpretative phenomenological analysis was undertaken. The emergent themes emanating from the research study revealed that social problems were pertinent factors to the lack of formulation of community social cohesion. Without this aspect, community building will be hampered, and thus cohesive neighbourhoods will be lacking. To this end, social innovation is proposed as a solution to the Zanemvula development. The issue of social development needs to placed back on the housing agenda, as is stated in the latest Housing Act.
- Full Text:
- Date Issued: 2019
- Authors: Williams-Bruinders, Leizel
- Date: 2019
- Subjects: Housing -- South Africa , City planning -- South Africa Cities and towns -- Research Urban geography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44390 , vital:37161
- Description: In the past twenty years we have seen the South African government deliver the largest number of houses in the world (NDHS, 2011). However, this great effort does not appeal to the principles that policies have set out in terms of equality. Along with the delivery of this high level of state funded housing, many of the RDP dwellers feel as though they have been marginalised and forced out of the area of opportunity, namely, the CBD and the northern suburbs (Huchzermeyer, 2003). Many researchers believe that the South African housing delivery pattern resembles that of apartheid segregationist planning, which exacerbated the social inequalities in the country (Huchzermeyer, 2003; Donaldson, 2001; Harrison et al., 2003). To gain an in-depth understanding of the lived experiences of residents of a low-cost housing settlement, an interpretative phenomenological analysis was undertaken. The emergent themes emanating from the research study revealed that social problems were pertinent factors to the lack of formulation of community social cohesion. Without this aspect, community building will be hampered, and thus cohesive neighbourhoods will be lacking. To this end, social innovation is proposed as a solution to the Zanemvula development. The issue of social development needs to placed back on the housing agenda, as is stated in the latest Housing Act.
- Full Text:
- Date Issued: 2019
Micro-structures, mineralogy, and chemistry of peritidal tufa stromatolites along the Eastern Cape coast
- Edwards, Mark Joseph Kalahari, Rishworth, Gavin M
- Authors: Edwards, Mark Joseph Kalahari , Rishworth, Gavin M
- Date: 2019
- Subjects: Mineralogy -- Analysis -- South Africa , Environmental forensics Environmental chemistry Stromatolites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39896 , vital:35503
- Description: Peritidal tufa microbialites occurring along the coast near Port Elizabeth, South Africa have been investigated from multiple disciplines and are found to be similar to supratidal tufa deposits in South West Australia. Studies have been conducted on the biological factors, geomorphology, ecosystems, and associated water chemistry. However, to date no mineralogical, micro-fabric, or geochemical analyses have been reported on these tufa deposits. This work, carried out at a previously well-studied area, provides the first study of this kind on the tufa. Chapter 1 is a mineralogical and micro-fabric analysis of the tufa deposits near Port Elizabeth for the purpose of classification and contextualisation. Chapter 2 provides the first geochemical study of these peritidal microbialites. X-Ray diffraction (XRD) investigations reveal dominance of low-Mg calcite in the mineral make-up of the tufa. A micro-structure analysis via thin section exposes a number of fabrics, suggesting various micro-facies: phytoherm boundstone (layered), phytoherm framestone (non-layered), lithoclast, and minor metazoan tufa. Scanning electron microscopy (SEM) images show micro- to nano- scale variation in calcite grains and epitaxial forms of needlefibre calcite (NFC). The elemental composition of the tufa deposits were examined by X-ray fluorescence (XRF), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS), and Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS). XRF and LA-ICP-MS were used to analyse the bulk rock chemistry while SEM/EDS was used to scrutinize specific areas within the tufa. These observations suggest the deposits are better classified as tufa microbialites (rather than exclusively “stromatolites”) and outline similarities and disparities to the micro-fabrics of supratidal tufa deposits in South West Australia, and Cape Morgan, South Africa. Here the Port Elizabeth tufa is shown to be similar, in terms of the dominant elements (O, Ca and to a lesser extent, Mg and Sr), to the Australian deposits despite subtle dissimilarities in water chemistry. Increasing trends toward more marine tufa for many elements are also shown here and can be explained by the interaction with increased amounts of sedimentary products and/or interactions with more saline water that contains a higher TDS (Total Dissolved Salts). This is also the first study to report needle-fibre calcite formation in stromatolites and the first to geochemically analyse modern peritidal microbialites.
- Full Text:
- Date Issued: 2019
- Authors: Edwards, Mark Joseph Kalahari , Rishworth, Gavin M
- Date: 2019
- Subjects: Mineralogy -- Analysis -- South Africa , Environmental forensics Environmental chemistry Stromatolites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39896 , vital:35503
- Description: Peritidal tufa microbialites occurring along the coast near Port Elizabeth, South Africa have been investigated from multiple disciplines and are found to be similar to supratidal tufa deposits in South West Australia. Studies have been conducted on the biological factors, geomorphology, ecosystems, and associated water chemistry. However, to date no mineralogical, micro-fabric, or geochemical analyses have been reported on these tufa deposits. This work, carried out at a previously well-studied area, provides the first study of this kind on the tufa. Chapter 1 is a mineralogical and micro-fabric analysis of the tufa deposits near Port Elizabeth for the purpose of classification and contextualisation. Chapter 2 provides the first geochemical study of these peritidal microbialites. X-Ray diffraction (XRD) investigations reveal dominance of low-Mg calcite in the mineral make-up of the tufa. A micro-structure analysis via thin section exposes a number of fabrics, suggesting various micro-facies: phytoherm boundstone (layered), phytoherm framestone (non-layered), lithoclast, and minor metazoan tufa. Scanning electron microscopy (SEM) images show micro- to nano- scale variation in calcite grains and epitaxial forms of needlefibre calcite (NFC). The elemental composition of the tufa deposits were examined by X-ray fluorescence (XRF), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS), and Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS). XRF and LA-ICP-MS were used to analyse the bulk rock chemistry while SEM/EDS was used to scrutinize specific areas within the tufa. These observations suggest the deposits are better classified as tufa microbialites (rather than exclusively “stromatolites”) and outline similarities and disparities to the micro-fabrics of supratidal tufa deposits in South West Australia, and Cape Morgan, South Africa. Here the Port Elizabeth tufa is shown to be similar, in terms of the dominant elements (O, Ca and to a lesser extent, Mg and Sr), to the Australian deposits despite subtle dissimilarities in water chemistry. Increasing trends toward more marine tufa for many elements are also shown here and can be explained by the interaction with increased amounts of sedimentary products and/or interactions with more saline water that contains a higher TDS (Total Dissolved Salts). This is also the first study to report needle-fibre calcite formation in stromatolites and the first to geochemically analyse modern peritidal microbialites.
- Full Text:
- Date Issued: 2019
A comparison of different strategies to control pests and diseases in Brassica spp. production in the Western Cape
- Van Niekerk, Abraham Johannes
- Authors: Van Niekerk, Abraham Johannes
- Date: 2019
- Subjects: Pesticides , Pests -- Control Agricultural pests , Plant diseases
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/44122 , vital:37113
- Description: Brassica spp. are cultivated all over the world, commercial species include: cabbage, broccoli, kale, kohlrabi and turnip. In this study the focus was on broccoli (Brassica oleracea) production in the Western Cape province of South Africa and its economically important pests and diseases: sugar beet cyst nematode (Heterodera schachtii), diamondback moth (Plutella xylostella), white blister (Albugo candida) and clubroot (Plasmodiophora brassicae), and the different methods to control these pests and diseases. The control methods focused on in this study included a commercial chemical control programme, a biological control programme and a holistic approach. Other factors were bio-fumigation and chemical fumigation and different crop rotation practices including rotation crops versus no rotation crops. The experimental design was a strip split plot design, with different pest and disease management strategies as the main plot treatment and fumigation and rotation treatment combinations arranged in strips across the main plot treatments. The main plot design was a randomized complete block with four programmes (Control, Holistic, Chemical and Biological) replicated four times and laid out in a Randomised Complete Block Design (RCBD). The treatment design of the strip plot factors was a 2x2 factorial with two fumigations (fumigated chemically and fumigated biologically) and two rotations (crop rotated and monoculture) randomly allocated across main plot treatments. Each experimental unit consisted of 40 plants. Plants were evaluated weekly for the incidence of white blister and diamondback moth. Incidences of clubroot and white blister infection of heads of broccoli were recorded 78 days after planting. Baseline soil samples were analysed to establish the soil chemical properties. Post-trial soil samples were also analysed to investigate the effect of the different practices and programmes on the soil chemical properties. Nematodes were extracted pre-trial and post-trial, and the effect of fumigation and crop rotation on plant parasitic nematodes and the nematode population diversity investigated. In the post-trial soil chemical analysis, a significantly higher concentration of Na was recorded for the biological programme when crop rotation was included compared to the no rotation treatment. The concentration of K was also significantly higher in the no rotation compared to the rotation treatment. The nematode results showed very high numbers of bacterial feeders in all the samples. Overall nematode diversity was lacking and showed very few fungal feeders, omnivores and predators. The nematode indices for all of the samples showed that nematodes were highly enriched and unstructured. Of the plant parasitic nematodes, only Heterodera spp. were obtained in the pre-trial analysis, and incidences of these nematodes were lower at the end of the trial. Low numbers of other plant parasitic nematodes viz. Pratylenchus, Paratrichodorus and Tylenchorhynchus were reported for the post-trial analysis of the soil. Because of the low numbers of plant parasitic nematodes, it was not possible to analyse the data statistically. With regard to diamondback moth and the fungal diseases, crop rotation and fumigation did not significantly affect the incidence of white blister and diamondback moth. A significant “days after planting by control programme” interaction was reported for the incidence of white blister on foliage and the incidence of diamondback moth. All three control programmes significantly reduced the incidence of diamondback moth with the chemical programme being significantly more effective than the other two programmes. All three programmes also significantly reduced the incidence of white blister on foliage and the holistic and biological programmes significantly reduced the incidence of white blister on broccoli heads with the holistic programme being significantly more effective than the biological programme. There was no clubroot infection in the trial for any of the treatments. Results of this study showed that it is possible to manage diseases and pests of broccoli using a holistic approach. However, long term trials are needed to confirm the results obtained in this study.
- Full Text:
- Date Issued: 2019
- Authors: Van Niekerk, Abraham Johannes
- Date: 2019
- Subjects: Pesticides , Pests -- Control Agricultural pests , Plant diseases
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/44122 , vital:37113
- Description: Brassica spp. are cultivated all over the world, commercial species include: cabbage, broccoli, kale, kohlrabi and turnip. In this study the focus was on broccoli (Brassica oleracea) production in the Western Cape province of South Africa and its economically important pests and diseases: sugar beet cyst nematode (Heterodera schachtii), diamondback moth (Plutella xylostella), white blister (Albugo candida) and clubroot (Plasmodiophora brassicae), and the different methods to control these pests and diseases. The control methods focused on in this study included a commercial chemical control programme, a biological control programme and a holistic approach. Other factors were bio-fumigation and chemical fumigation and different crop rotation practices including rotation crops versus no rotation crops. The experimental design was a strip split plot design, with different pest and disease management strategies as the main plot treatment and fumigation and rotation treatment combinations arranged in strips across the main plot treatments. The main plot design was a randomized complete block with four programmes (Control, Holistic, Chemical and Biological) replicated four times and laid out in a Randomised Complete Block Design (RCBD). The treatment design of the strip plot factors was a 2x2 factorial with two fumigations (fumigated chemically and fumigated biologically) and two rotations (crop rotated and monoculture) randomly allocated across main plot treatments. Each experimental unit consisted of 40 plants. Plants were evaluated weekly for the incidence of white blister and diamondback moth. Incidences of clubroot and white blister infection of heads of broccoli were recorded 78 days after planting. Baseline soil samples were analysed to establish the soil chemical properties. Post-trial soil samples were also analysed to investigate the effect of the different practices and programmes on the soil chemical properties. Nematodes were extracted pre-trial and post-trial, and the effect of fumigation and crop rotation on plant parasitic nematodes and the nematode population diversity investigated. In the post-trial soil chemical analysis, a significantly higher concentration of Na was recorded for the biological programme when crop rotation was included compared to the no rotation treatment. The concentration of K was also significantly higher in the no rotation compared to the rotation treatment. The nematode results showed very high numbers of bacterial feeders in all the samples. Overall nematode diversity was lacking and showed very few fungal feeders, omnivores and predators. The nematode indices for all of the samples showed that nematodes were highly enriched and unstructured. Of the plant parasitic nematodes, only Heterodera spp. were obtained in the pre-trial analysis, and incidences of these nematodes were lower at the end of the trial. Low numbers of other plant parasitic nematodes viz. Pratylenchus, Paratrichodorus and Tylenchorhynchus were reported for the post-trial analysis of the soil. Because of the low numbers of plant parasitic nematodes, it was not possible to analyse the data statistically. With regard to diamondback moth and the fungal diseases, crop rotation and fumigation did not significantly affect the incidence of white blister and diamondback moth. A significant “days after planting by control programme” interaction was reported for the incidence of white blister on foliage and the incidence of diamondback moth. All three control programmes significantly reduced the incidence of diamondback moth with the chemical programme being significantly more effective than the other two programmes. All three programmes also significantly reduced the incidence of white blister on foliage and the holistic and biological programmes significantly reduced the incidence of white blister on broccoli heads with the holistic programme being significantly more effective than the biological programme. There was no clubroot infection in the trial for any of the treatments. Results of this study showed that it is possible to manage diseases and pests of broccoli using a holistic approach. However, long term trials are needed to confirm the results obtained in this study.
- Full Text:
- Date Issued: 2019
The socio-economic importance of indigenous vegetables to the Ntuze smallholder farming community in KwaZulu-Natal, South Africa
- Authors: Qwabe, Qinisani Nhlakanipho
- Date: 2019
- Subjects: Indigenous crops -- Economic aspects -- South Africa -- KwaZulu Natal , Vegetables -- South Africa -- KwaZulu Natal Farmers -- Economic aspects -- South Africa -- KwaZulu Natal , Farms, Small -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30287 , vital:30927
- Description: South Africa continues to face multiple socio-economic challenges – one of the direst being food insecurity, especially in rural areas. Compounding the challenges is the impact of changing weather patterns on agriculture. The current study presents evidence indicating that indigenous vegetables provide a sustainable yet inexpensive answer to several of these challenges. The research was aimed at determining the socio-economic impact of indigenous vegetables in the Ntuze community of northern KwaZulu-Natal. A mixed-methods methodology was employed to achieve a holistic understanding of the relationship between the use of indigenous vegetables and socio-economic influences. The study discovered that indigenous vegetables play an important role in the livelihood strategy of this rural farming community. Findings revealed that the utilisation of indigenous vegetables makes an essential contribution to the livelihoods and well-being of the Ntuze people, especially in terms of curbing food poverty, income generation and medicinal benefits. However, the value of these vegetables was found to be appreciated mostly by the elderly. Conclusions therefore indicate a possible decline in future production and use of indigenous vegetables if indigenous knowledge is not passed on to the next generation. Integration of indigenous knowledge in agricultural technology transfer programmes is therefore vital to promote production of indigenous vegetables as a sustainable food resource. Actively addressing the stigma attached to indigenous vegetables as being “low-status food” is also crucial to enhance perception and understanding of the value of these vegetables. This would contribute to both preserving cultural heritage and conserving valuable indigenous flora. Such intervention would safeguard this sustainable and renewable resource in its pivotal socio-economic role in terms of rural food security as is substantiated by this study.
- Full Text:
- Date Issued: 2019
- Authors: Qwabe, Qinisani Nhlakanipho
- Date: 2019
- Subjects: Indigenous crops -- Economic aspects -- South Africa -- KwaZulu Natal , Vegetables -- South Africa -- KwaZulu Natal Farmers -- Economic aspects -- South Africa -- KwaZulu Natal , Farms, Small -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30287 , vital:30927
- Description: South Africa continues to face multiple socio-economic challenges – one of the direst being food insecurity, especially in rural areas. Compounding the challenges is the impact of changing weather patterns on agriculture. The current study presents evidence indicating that indigenous vegetables provide a sustainable yet inexpensive answer to several of these challenges. The research was aimed at determining the socio-economic impact of indigenous vegetables in the Ntuze community of northern KwaZulu-Natal. A mixed-methods methodology was employed to achieve a holistic understanding of the relationship between the use of indigenous vegetables and socio-economic influences. The study discovered that indigenous vegetables play an important role in the livelihood strategy of this rural farming community. Findings revealed that the utilisation of indigenous vegetables makes an essential contribution to the livelihoods and well-being of the Ntuze people, especially in terms of curbing food poverty, income generation and medicinal benefits. However, the value of these vegetables was found to be appreciated mostly by the elderly. Conclusions therefore indicate a possible decline in future production and use of indigenous vegetables if indigenous knowledge is not passed on to the next generation. Integration of indigenous knowledge in agricultural technology transfer programmes is therefore vital to promote production of indigenous vegetables as a sustainable food resource. Actively addressing the stigma attached to indigenous vegetables as being “low-status food” is also crucial to enhance perception and understanding of the value of these vegetables. This would contribute to both preserving cultural heritage and conserving valuable indigenous flora. Such intervention would safeguard this sustainable and renewable resource in its pivotal socio-economic role in terms of rural food security as is substantiated by this study.
- Full Text:
- Date Issued: 2019
Epibenthic biodiversity, habitat characterisation and anthropogenic pressure mapping of unconsolidated sediment habitats in Algoa Bay, South Africa
- Authors: Truter, Hannah Jessie
- Date: 2019
- Subjects: Aquatic ecology , Marine sciences Conservation biology Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43812 , vital:37049
- Description: Implementation of an ecosystem-based management approach for marine systems requires a comprehensive understanding of the biophysical marine environment and the cumulative human impacts at different spatio-temporal scales. In Algoa Bay, South Africa, this study describes the epibenthic communities occurring in unconsolidated marine habitats. It further investigates the potential abiotic factors that influence their distribution and abundance, compares epibenthic communities with existing habitat information and evaluates the protection status of the marine environment in the Bay. Seabed imagery, covering a total area of 171.4m², and sediment samples were collected from 13 stations from which 106 epibenthic species were identified. Multivariate analyses revealed two statistically distinct communities that did not align with the Algoa Bay benthic habitat types defined in the current National Biodiversity Assessment (NBA, 2012). Further assessment indicated that community differences were driven by the presence of rock substrate. A range of abiotic factors were tested against the epibenthic communities to explore patterns and identify potential drivers. The combination of abiotic factors depth, mean grain size, mean bottom temperature and mean bottom current explained 55% fitted variation in epibenthic data. The degree of long-term variability in several of these parameters were likewise identified as explanatory variables, including bottom temperature, current speed and dissolved oxygen. The link between abiotic factors and the epibenthic communities observed indicate that these variables can act as surrogates for habitat mapping in the future. The existing and proposed Marine Protected Area (MPA) in conjunction with the NBA 2012 habitat types does well in protecting the majority of habitats in the Bay, however there remain habitats that lack protection. Utilising the benthic communities and potential drivers identified in this study, the proposed MPA boundary delineations should be somewhat altered to include missing habitat types.
- Full Text:
- Date Issued: 2019
- Authors: Truter, Hannah Jessie
- Date: 2019
- Subjects: Aquatic ecology , Marine sciences Conservation biology Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43812 , vital:37049
- Description: Implementation of an ecosystem-based management approach for marine systems requires a comprehensive understanding of the biophysical marine environment and the cumulative human impacts at different spatio-temporal scales. In Algoa Bay, South Africa, this study describes the epibenthic communities occurring in unconsolidated marine habitats. It further investigates the potential abiotic factors that influence their distribution and abundance, compares epibenthic communities with existing habitat information and evaluates the protection status of the marine environment in the Bay. Seabed imagery, covering a total area of 171.4m², and sediment samples were collected from 13 stations from which 106 epibenthic species were identified. Multivariate analyses revealed two statistically distinct communities that did not align with the Algoa Bay benthic habitat types defined in the current National Biodiversity Assessment (NBA, 2012). Further assessment indicated that community differences were driven by the presence of rock substrate. A range of abiotic factors were tested against the epibenthic communities to explore patterns and identify potential drivers. The combination of abiotic factors depth, mean grain size, mean bottom temperature and mean bottom current explained 55% fitted variation in epibenthic data. The degree of long-term variability in several of these parameters were likewise identified as explanatory variables, including bottom temperature, current speed and dissolved oxygen. The link between abiotic factors and the epibenthic communities observed indicate that these variables can act as surrogates for habitat mapping in the future. The existing and proposed Marine Protected Area (MPA) in conjunction with the NBA 2012 habitat types does well in protecting the majority of habitats in the Bay, however there remain habitats that lack protection. Utilising the benthic communities and potential drivers identified in this study, the proposed MPA boundary delineations should be somewhat altered to include missing habitat types.
- Full Text:
- Date Issued: 2019
Cheetah Acinonyx jubatus behaviour and resource use in response to other African large carnivores
- Authors: Cornhill, Kristina
- Date: 2019
- Subjects: Cheetahs -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44735 , vital:38169
- Description: Competition occurs between species for shared resources. Subordinate species employ resource selection to shift their resource use away from that of dominant species in order to avoid the negative consequences of competition. Only in Africa is the post-Pleistocene large carnivore guild intact, consisting of lions Panthera leo, spotted hyaenas Crocuta crocuta, leopards Panthera pardus, cheetahs Acinonyx jubatus, and African wild dogs Lycaon pictus. Therefore, only in Africa can we explore how large carnivores co-exist with one another in a diverse community. Cheetahs are a subordinate member of the large carnivore guild due to their small stature and solitary nature. However, we still do not fully understand how competition shapes cheetah behaviour and resource use. I used cheetahs as a model subordinate predator to determine the behavioural responses and resource selection of cheetah in response to assumed competition from other large carnivores. I experimentally explored the behavioural response of cheetah to large carnivore scent sources (scats) and their presence at cheetah scent-marking sites to test for avoidance of such cues. Moreover, using unplanned experiments based on the resource use of cheetahs in the absence and then presence of lions (assessing space and time use by cheetah) and African wild dogs (assessing prey use by both species), I evaluated resource selection by cheetahs as a way to reduce competition with these large carnivores. In addition, I measured spatial and temporal partitioning between cheetahs and all four large carnivores at camera trap sites. Finally, I assessed whether cheetahs responded to competitors using a long term proactive response or a short term reactive response. I found that all four of the other large carnivores in the guild shaped cheetahs resource use, however, all did so on different axes in accordance with the niche complementarity hypothesis. Lions and spotted hyenas were avoided through time, African wild dogs through space and prey use, and lions and leopards on the spatiotemporal axis. Moreover, I show that cheetahs utilize a reactive response to competition that allows them to avoid risk while still obtaining necessary resources.
- Full Text:
- Date Issued: 2019
- Authors: Cornhill, Kristina
- Date: 2019
- Subjects: Cheetahs -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44735 , vital:38169
- Description: Competition occurs between species for shared resources. Subordinate species employ resource selection to shift their resource use away from that of dominant species in order to avoid the negative consequences of competition. Only in Africa is the post-Pleistocene large carnivore guild intact, consisting of lions Panthera leo, spotted hyaenas Crocuta crocuta, leopards Panthera pardus, cheetahs Acinonyx jubatus, and African wild dogs Lycaon pictus. Therefore, only in Africa can we explore how large carnivores co-exist with one another in a diverse community. Cheetahs are a subordinate member of the large carnivore guild due to their small stature and solitary nature. However, we still do not fully understand how competition shapes cheetah behaviour and resource use. I used cheetahs as a model subordinate predator to determine the behavioural responses and resource selection of cheetah in response to assumed competition from other large carnivores. I experimentally explored the behavioural response of cheetah to large carnivore scent sources (scats) and their presence at cheetah scent-marking sites to test for avoidance of such cues. Moreover, using unplanned experiments based on the resource use of cheetahs in the absence and then presence of lions (assessing space and time use by cheetah) and African wild dogs (assessing prey use by both species), I evaluated resource selection by cheetahs as a way to reduce competition with these large carnivores. In addition, I measured spatial and temporal partitioning between cheetahs and all four large carnivores at camera trap sites. Finally, I assessed whether cheetahs responded to competitors using a long term proactive response or a short term reactive response. I found that all four of the other large carnivores in the guild shaped cheetahs resource use, however, all did so on different axes in accordance with the niche complementarity hypothesis. Lions and spotted hyenas were avoided through time, African wild dogs through space and prey use, and lions and leopards on the spatiotemporal axis. Moreover, I show that cheetahs utilize a reactive response to competition that allows them to avoid risk while still obtaining necessary resources.
- Full Text:
- Date Issued: 2019
Top-soil water retention in organic and conventional farming systems in South Africa’s Southern Cape
- Authors: Eckert, Catherine Jessica
- Date: 2019
- Subjects: Water harvesting , Soil moisture conservation Organic farming Sustainable agriculture
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39885 , vital:35500
- Description: With the world’s growing population and limited natural resources, there is a need to produce more food using less inputs. A major limiting factor to meeting the agricultural production needs of the growing population is fresh water. Water is a critical resource in agriculture and may be more of a limiting factor than other crop growth requirements in some areas. Furthermore, water availability is being impacted by climate change and competition from other industries. Methods of improving crop water use efficiency through conservation of water and the enhancement of crop growth need to be employed to meet the growing demand sustainably. The purpose of the research was to assess the differences in soil water status between organically farmed crops with a grass mulch and conventionally farmed crops without mulch, with a view to making more efficient use of the water resource. This research was conducted at the Mandela long term organic farming systems research trial site at Nelson Mandela University, George campus in the southern Cape, South Africa. It is part of a larger research project (the Mandela Trials) in which various researchers have been involved in different aspects of this trial including agronomy, microbiology and pest and disease control. This research took place over two seasons, namely, 2016-2017 season and 2017-2018 season. The soil water content (SWC) of organic and conventional plots were measured using fixed capacitance probes that recorded continuous data, every half hour, at depths of 10, 30 and 50 cm. A handheld theta probe was also used to measure the SWC in the top 6 cm of the soil at 7 to14 day intervals. The organic treatment had a significantly higher SWC than the conventional treatment over the two seasons in which this research was conducted. In addition, soil carbon was significantly higher in the organic treatment, than the conventional. Organic farming methods preserve and promote an increase in soil organic matter, thus improving the soil structure and increasing the soil’s water holding capacity. From this research, it is concluded that organic farming practices can be used to help conserve SWC, keeping it available to crops for longer and helping farmers make more efficient use of this scarce resource. This is especially relevant for low rainfall areas which are affected by water shortages. The improved SWC availability should be coupled with good agronomic practices to increase productive water losses and the conversion of water to yields, thus increasing water use efficiency. In addition, adding organic matter to the soil will improve resilience of the soil and help sequester carbon and thus help in mitigating climate change.
- Full Text:
- Date Issued: 2019
Top-soil water retention in organic and conventional farming systems in South Africa’s Southern Cape
- Authors: Eckert, Catherine Jessica
- Date: 2019
- Subjects: Water harvesting , Soil moisture conservation Organic farming Sustainable agriculture
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/39885 , vital:35500
- Description: With the world’s growing population and limited natural resources, there is a need to produce more food using less inputs. A major limiting factor to meeting the agricultural production needs of the growing population is fresh water. Water is a critical resource in agriculture and may be more of a limiting factor than other crop growth requirements in some areas. Furthermore, water availability is being impacted by climate change and competition from other industries. Methods of improving crop water use efficiency through conservation of water and the enhancement of crop growth need to be employed to meet the growing demand sustainably. The purpose of the research was to assess the differences in soil water status between organically farmed crops with a grass mulch and conventionally farmed crops without mulch, with a view to making more efficient use of the water resource. This research was conducted at the Mandela long term organic farming systems research trial site at Nelson Mandela University, George campus in the southern Cape, South Africa. It is part of a larger research project (the Mandela Trials) in which various researchers have been involved in different aspects of this trial including agronomy, microbiology and pest and disease control. This research took place over two seasons, namely, 2016-2017 season and 2017-2018 season. The soil water content (SWC) of organic and conventional plots were measured using fixed capacitance probes that recorded continuous data, every half hour, at depths of 10, 30 and 50 cm. A handheld theta probe was also used to measure the SWC in the top 6 cm of the soil at 7 to14 day intervals. The organic treatment had a significantly higher SWC than the conventional treatment over the two seasons in which this research was conducted. In addition, soil carbon was significantly higher in the organic treatment, than the conventional. Organic farming methods preserve and promote an increase in soil organic matter, thus improving the soil structure and increasing the soil’s water holding capacity. From this research, it is concluded that organic farming practices can be used to help conserve SWC, keeping it available to crops for longer and helping farmers make more efficient use of this scarce resource. This is especially relevant for low rainfall areas which are affected by water shortages. The improved SWC availability should be coupled with good agronomic practices to increase productive water losses and the conversion of water to yields, thus increasing water use efficiency. In addition, adding organic matter to the soil will improve resilience of the soil and help sequester carbon and thus help in mitigating climate change.
- Full Text:
- Date Issued: 2019
Finding Frankenflora: investigating hybridisation between local and introduced Protea species at the Van Stadens Wildflower Reserve
- Authors: Macqueen, Timothy
- Date: 2019
- Subjects: Proteaceae -- South Africa , Proteaceae Trees -- South Africa Hybridization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40724 , vital:36230
- Description: This study provides an overview of hybridisation and methods to detect it in plants. This is documented in chapter 1. Another aim was to identify hybridisation between local and non-local species in the Proteaceae. This is covered in chapter 2. Finally the third aim was to develop a cheap and rapidly working method of detecting hybrids in this system. This is detailed in chapter 3. The model system for this research is the Van Stadens Wildflower Reserve. In 1984 the reserve manager introduced the non-local species, Protea susannae from Cape Agulhas. This represents a long-distance dispersal of over 600 km. This study is focused on looking at the impacts of the introduction of P. susannae on the local species P. eximia. I use genetic and morphological methods to detect hybrids. Hybridisation and the methods implemented to identify it are reviewed and discussed (Chapter 1). Morphological traits of the two species and direct sequencing of the nuclear ITS and chloroplast regions are compared (Chapter 2). This includes notes on the detection of hybrids and the potential for cryptic hybrids. I also focussed on testing of two rapid and low-cost techniques for detecting hybrids using Species Specific Primers (SSP’s) and High Resolution Melt (HRM). The Sanger sequencing method and ITS detected cryptic hybrids. The HRM was able to detect hybrids when comparing F1 putative hybrids to a ‘pure’ parent populations, but was not able to detect between a ‘pure’ parent population and F3 or F4 putative hybrids in the Van Stadens system. The SSP’s had the highest hybrid detection rate. Genetic methods, specifically the SSP’s were found to work well to detect hybrids in an environment where a hybrid swarm has taken place. The maps produced from this thesis will be useful for determining the distribution of hybrids in the reserve and for other similar hybrid systems. Long distance dispersal of Cape species may lead to the loss of genetic diversity or species as local and non-local hybridisation may occur, similar to the hybridisation between P. susannae and P. eximia in the Van Stadens Wild Flower Reserve. Genetic methods were shown to be superior to morphological hybrid detection (i.e. Sanger sequencing and SSP’s). The SSP approach tested here, which is dependent on the presence of fixed species specific SNP’s (Single Nucleotide Polymorphisms), could offer a rapid and effective method to explore hybridisation through space and time.
- Full Text:
- Date Issued: 2019
- Authors: Macqueen, Timothy
- Date: 2019
- Subjects: Proteaceae -- South Africa , Proteaceae Trees -- South Africa Hybridization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40724 , vital:36230
- Description: This study provides an overview of hybridisation and methods to detect it in plants. This is documented in chapter 1. Another aim was to identify hybridisation between local and non-local species in the Proteaceae. This is covered in chapter 2. Finally the third aim was to develop a cheap and rapidly working method of detecting hybrids in this system. This is detailed in chapter 3. The model system for this research is the Van Stadens Wildflower Reserve. In 1984 the reserve manager introduced the non-local species, Protea susannae from Cape Agulhas. This represents a long-distance dispersal of over 600 km. This study is focused on looking at the impacts of the introduction of P. susannae on the local species P. eximia. I use genetic and morphological methods to detect hybrids. Hybridisation and the methods implemented to identify it are reviewed and discussed (Chapter 1). Morphological traits of the two species and direct sequencing of the nuclear ITS and chloroplast regions are compared (Chapter 2). This includes notes on the detection of hybrids and the potential for cryptic hybrids. I also focussed on testing of two rapid and low-cost techniques for detecting hybrids using Species Specific Primers (SSP’s) and High Resolution Melt (HRM). The Sanger sequencing method and ITS detected cryptic hybrids. The HRM was able to detect hybrids when comparing F1 putative hybrids to a ‘pure’ parent populations, but was not able to detect between a ‘pure’ parent population and F3 or F4 putative hybrids in the Van Stadens system. The SSP’s had the highest hybrid detection rate. Genetic methods, specifically the SSP’s were found to work well to detect hybrids in an environment where a hybrid swarm has taken place. The maps produced from this thesis will be useful for determining the distribution of hybrids in the reserve and for other similar hybrid systems. Long distance dispersal of Cape species may lead to the loss of genetic diversity or species as local and non-local hybridisation may occur, similar to the hybridisation between P. susannae and P. eximia in the Van Stadens Wild Flower Reserve. Genetic methods were shown to be superior to morphological hybrid detection (i.e. Sanger sequencing and SSP’s). The SSP approach tested here, which is dependent on the presence of fixed species specific SNP’s (Single Nucleotide Polymorphisms), could offer a rapid and effective method to explore hybridisation through space and time.
- Full Text:
- Date Issued: 2019
On the study of the performance of Photovoltaic power plants
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
- Authors: Serameng, Tshepo Joba
- Date: 2019
- Subjects: Photovoltaic power generation , Solar energy Power resources Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43401 , vital:36873
- Description: Performance monitoring of different module technologies and system configurations of photovoltaic (PV) systems in South Africa is rare, resulting in-few reports being published based on field results of PV systems installed and operated in South Africa. The goal of this work was to analyse and report on the performance of PV systems by evaluating the energy output of various PV system configurations and module technologies in the central part of South African (southern hemisphere) climatic conditions. To achieve this, a 400 kWp PV Solar plant has been installed and monitored since January 2015 at the Eskom Research and Innovation Centre (ERIC) in Rosherville, Gauteng (26°5'5" South, 28°5 8'1" East and 1625 m above mean sea level). The ERIC plant consists of multi-crystalline silicon (mc-Si) and copper indium gallium selenide (CIGS) thin-film technologies. The plant comprises of two 25° fixed-tilt north facing arrays, two east-west single axis tracking arrays and two 10° fixed shed orientation (East and West) for both module technologies and one north-south single axis tracking for mc-Si. The evaluation was achieved by studying the operation of the PV plant under different weather conditions and the impact of different configurations and technologies by analysing mainly in terms of specific yields normalized per m2 (kWh/kWp/m2). The first part of the study investigates the impact on the overall performance of different PV technologies as a function of the module mounting configuration. The second part presents the PVSyst yield validation for the Eskom Research and Innovation Centre (ERIC) solar PV plant. Normalised yield production calculations were performed for a fair comparison of various configurations. Although CIGS technology has a higher specific yield throughout the year, the normalised yield production per m2 shows that mc-Si technology out-performs CIGS in both fixed north facing and east-west tracking configurations. This study provides an insight to identify the optimal configuration and will also give an indication of suitability of PV technology for deployment in the central part of South Africa, once all design parameters are considered. This information is also useful in evaluating the operational benefits of the plant based on the net energy output. The monitored data and operating experience of the reported PV system can be applied for future projects. It is common at the beginning of any project for photovoltaic (PV) simulation tools to be utilized for yield prediction in order to estimate performance that can be expected. The purpose for PVSyst yield validation in this study was to validate the accuracy of the original PVSyst simulation that were performed using the satellite derived data, PVGIS satellite database for the ERIC PV plant. The validation is done using the actual ground measured solar resource datasets on site by importing them into PVSyst. A brief analysis of the results suggests that the PVSyst model seems to overestimate the yield output relative to the measured values. This due to out-door conditions and environmental factors impacting the PV site. These factors include power outages, module degradation and were unknown during the development phases when original simulations were performed. However, based on the statistical criteria and assessment, it can be concluded that the original PVSyst simulation results are accurate enough as per the MBE and RMSE percentages, however it is noted as well that the modified PVSyst results are more correlated to the measured results in comparison.
- Full Text:
- Date Issued: 2019
The distribution of South African loggerhead sea turtles (Caretta caretta) as indicated by epibionts and stable isotopes
- Authors: Nolte, Christopher Robin
- Date: 2019
- Subjects: Sea turtles -- South Africa , Loggerhead turtle -- South Africa Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31611 , vital:31625
- Description: Many marine species undertake long-distance migrations as part of their life history strategies, and so form an important part of marine ecosystems performing a range of functions, across many habitats. However, these migratory species, including sea turtles, face multiple threats and anthropogenic impacts across their ranges and knowing their movement and distribution patterns enables more effective and appropriate conservation strategies to be devised. Satellite telemetry has provided invaluable information on spatial distribution of marine migrants, but applying this approach to a large proportion of a population is often unfeasible and costly. This study aimed to identify alternative, more cost effective methods that could assist with tracking animal movements across a larger proportion of a population of marine focal species, such as sea turtles. This study used nesting loggerhead sea turtles (Caretta caretta) from the iSimangaliso Wetland Park, South Africa as a model species to test these alternative methods and subsequently combine body condition, habitat use, and distribution range in the South West Indian Ocean. First, epibiont community assemblages were investigated as a proxy to determine sea turtle body condition. A body condition index was created using plastron shape, injuries and skin deformities. Sixty turtles were classified into four body condition categories ranging from poor to very good and this was reflected in their epibiont communities as both species abundance and richness increased with a decline in body condition. A total of twenty-eight epibiont taxa were identified from a range of systematic groups including, but not limited to, Amphipoda, Cirripedia, Brachyura and Polychaeta. The barnacle Chelonibia testudinaria showed the greatest variation among different body conditions with an increase in abundance as turtle body condition deteriorated. These results suggest that epibiont load can be used as an indicator of body condition that is easy to implement in the field. Second, a combination of organic δ13C and δ15N isotopic signatures of turtle epidermis and epibiont communities was used to infer foraging habitat. One hundred and seventy turtles were sampled for stable isotope analysis. These turtles were clustered into two groups based on δ13C at -13.61 ‰ with relative depletion or enrichment indicating foraging in oceanic or neritic environments, respectively. The epibiont communities of IV 80 turtles closely followed this cluster grouping; turtles with depleted δ13C had a higher abundance and frequency of oceanic epibiont species, such Lepas spp. Similarly, three neritic epibionts (Hyale grandicornis, Hyachelia tortugae and Podocerus africanus) were the other habitat-specific species driving community assemblages, with higher occurrence and abundance on turtles in the enriched δ13C cluster. Additionally, the size of the dietary niche was determined by a Bayesian analysis of δ13C and δ15N for 46 turtles in different body condition categories. Although there was overlap among categories, individuals in very good body condition had the smallest dietary niche. These results show the complementarity of using epibionts and stable isotope analysis in determining foraging area. Third, Chelonibia testudinaria barnacles on sea turtles were analysed for δ18O and inorganic δ13C. The δ18O of expected calcite fractionation was mapped for the known migration routes of eight turtles in the South West Indian Ocean. The inorganic carbon values were not very informative on movement, however, the δ18O analysis of the barnacle showed the range of the turtle host moving through the isoscape. Most of the turtles migrated from the north in the Mozambique Channel, to the southern rookery in South Africa, which is in accordance with reports from tag recoveries and satellite telemetry studies. Using this approach to track migratory species that have epibiotic barnacles can provide complimentary approach to satellite tracking that can be used on more individuals within a population. This study aids in providing alternative methods to study body condition, habitat use and regional movement of loggerhead sea turtles. These approaches can be applied to other sea turtle species and migratory marine fauna to help better understand their movement patterns thereby promoting more effective conservation strategies. Future work should consider incorporating different cohorts, examining other epibionts such as meiofauna and diatoms, including additional isotope and trace elements for analysis on habitat and improving the resolution of the isoscape data for δ18O of seawater in the SWIO.
- Full Text:
- Date Issued: 2019
- Authors: Nolte, Christopher Robin
- Date: 2019
- Subjects: Sea turtles -- South Africa , Loggerhead turtle -- South Africa Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31611 , vital:31625
- Description: Many marine species undertake long-distance migrations as part of their life history strategies, and so form an important part of marine ecosystems performing a range of functions, across many habitats. However, these migratory species, including sea turtles, face multiple threats and anthropogenic impacts across their ranges and knowing their movement and distribution patterns enables more effective and appropriate conservation strategies to be devised. Satellite telemetry has provided invaluable information on spatial distribution of marine migrants, but applying this approach to a large proportion of a population is often unfeasible and costly. This study aimed to identify alternative, more cost effective methods that could assist with tracking animal movements across a larger proportion of a population of marine focal species, such as sea turtles. This study used nesting loggerhead sea turtles (Caretta caretta) from the iSimangaliso Wetland Park, South Africa as a model species to test these alternative methods and subsequently combine body condition, habitat use, and distribution range in the South West Indian Ocean. First, epibiont community assemblages were investigated as a proxy to determine sea turtle body condition. A body condition index was created using plastron shape, injuries and skin deformities. Sixty turtles were classified into four body condition categories ranging from poor to very good and this was reflected in their epibiont communities as both species abundance and richness increased with a decline in body condition. A total of twenty-eight epibiont taxa were identified from a range of systematic groups including, but not limited to, Amphipoda, Cirripedia, Brachyura and Polychaeta. The barnacle Chelonibia testudinaria showed the greatest variation among different body conditions with an increase in abundance as turtle body condition deteriorated. These results suggest that epibiont load can be used as an indicator of body condition that is easy to implement in the field. Second, a combination of organic δ13C and δ15N isotopic signatures of turtle epidermis and epibiont communities was used to infer foraging habitat. One hundred and seventy turtles were sampled for stable isotope analysis. These turtles were clustered into two groups based on δ13C at -13.61 ‰ with relative depletion or enrichment indicating foraging in oceanic or neritic environments, respectively. The epibiont communities of IV 80 turtles closely followed this cluster grouping; turtles with depleted δ13C had a higher abundance and frequency of oceanic epibiont species, such Lepas spp. Similarly, three neritic epibionts (Hyale grandicornis, Hyachelia tortugae and Podocerus africanus) were the other habitat-specific species driving community assemblages, with higher occurrence and abundance on turtles in the enriched δ13C cluster. Additionally, the size of the dietary niche was determined by a Bayesian analysis of δ13C and δ15N for 46 turtles in different body condition categories. Although there was overlap among categories, individuals in very good body condition had the smallest dietary niche. These results show the complementarity of using epibionts and stable isotope analysis in determining foraging area. Third, Chelonibia testudinaria barnacles on sea turtles were analysed for δ18O and inorganic δ13C. The δ18O of expected calcite fractionation was mapped for the known migration routes of eight turtles in the South West Indian Ocean. The inorganic carbon values were not very informative on movement, however, the δ18O analysis of the barnacle showed the range of the turtle host moving through the isoscape. Most of the turtles migrated from the north in the Mozambique Channel, to the southern rookery in South Africa, which is in accordance with reports from tag recoveries and satellite telemetry studies. Using this approach to track migratory species that have epibiotic barnacles can provide complimentary approach to satellite tracking that can be used on more individuals within a population. This study aids in providing alternative methods to study body condition, habitat use and regional movement of loggerhead sea turtles. These approaches can be applied to other sea turtle species and migratory marine fauna to help better understand their movement patterns thereby promoting more effective conservation strategies. Future work should consider incorporating different cohorts, examining other epibionts such as meiofauna and diatoms, including additional isotope and trace elements for analysis on habitat and improving the resolution of the isoscape data for δ18O of seawater in the SWIO.
- Full Text:
- Date Issued: 2019
β-N-Methylamino-L-Alanine is a developmental neurotoxin
- Authors: Scott, Laura Louise
- Date: 2019
- Subjects: Neurotoxic agents , Nervous system -- Diseases
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43633 , vital:36949
- Description: β-N-methylamino-L-alanine (BMAA) has been implicated in the development of the neurodegenerative diseases Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC), Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s Disease (AD), but to date no animal model has adequately substantiated this link at environmentally relevant or even exaggerated BMAA exposure levels. The resulting controversy over a possible role for BMAA in neurodegenerative diseases was further hampered by a lack of evidence for mechanistic explanation for the disease pathology associated with these diseases However, the different responses to BMAA that have been observed in neonatal compared to adult rats, together with the findings of epidemiological studies that exposure to environmental factors in utero or in the early stages of life may be important for the development of ALS several years later, suggested that age of exposure might be the determining factor of BMAA neurotoxicity. This study therefore specifically addresses the developmental nature of BMAA as a neurotoxin, and investigates the pathology and progressive nature of that pathology after exposure to the toxin at the most susceptible age. This study demonstrated the importance of BMAA exposure age over total BMAA dose by showing that the administration of a single neonatal dose of BMAA to rodents on postnatal day (PND) 3, 4 and 5, and not prenatally or on PND 6, 7 and 10, caused behavioural, locomotor, emotional and long-term cognitive deficits, clinical symptoms of neurodegeneration as well as pathological hallmarks of AD, PD and ALS in the central nervous system. Furthermore, the observed behavioural deficits and distribution of neuronal loss and proteinopathies in the rodent central nervous system following exposure to BMAA on PND 3, 4 and 5 (corresponding to the developing age of an infant during the third trimester of pregnancy) is consistent with that typically associated with the disruption of normal dopamine and/or serotonin signaling in the brain and the consequent alteration in normal hippocampal and striatal neurogenesis that is modulated, in part, by dopamine. The pattern of spread and rate of propagation of pathology in this neonatal rat BMAA model provided further evidence that BMAA potentially exerts its effect by acting on neurotransmitter signaling. The observed late onset of typical ALS symptoms and pathology suggest that in this BMAA model AD and/or PD related symptoms develop first, followed by the start of ALS symptoms only after the AD and/or PD neuropathological deficits have severely progressed. This study also demonstrated that BMAA exposure at different doses and at different developmental ages resulted in the development of different combinations of either AD and/or PD and/or ALS pathology and/or symptoms in rats, and it is therefore feasible that in humans the age and/or frequency of exposure as well as the BMAA dose might similarly be a major determinant of the variant of AD, PD and/or ALS that might develop in adulthood. Based on the low BMAA dose that was able to cause AD and/or PD-like neuropathological abnormalities in rats in this study, it is feasible that a pregnant human could over the course of her pregnancy, and specifically during the third trimester of pregnancy, consume sufficient BMAA to result in her unborn child developing AD and/or PD and/or ALS up to 30-50 years later. This neonatal BMAA model is the only non-transgenic rodent model that reproduces the behavioural deficits, neuropathology and clinical symptoms that are typically associated with AD, PD and ALS in humans and that, more importantly, mimics the delayed onset of disease symptoms and typical slow progression of these neurodegenerative diseases with age. It now seems very likely that BMAA is a developmental neurotoxin that, as a result of perinatal, but probably prenatal exposure, causes or contributes significantly to the development of neurodegenerative diseases in humans.
- Full Text:
- Date Issued: 2019
- Authors: Scott, Laura Louise
- Date: 2019
- Subjects: Neurotoxic agents , Nervous system -- Diseases
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43633 , vital:36949
- Description: β-N-methylamino-L-alanine (BMAA) has been implicated in the development of the neurodegenerative diseases Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC), Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s Disease (AD), but to date no animal model has adequately substantiated this link at environmentally relevant or even exaggerated BMAA exposure levels. The resulting controversy over a possible role for BMAA in neurodegenerative diseases was further hampered by a lack of evidence for mechanistic explanation for the disease pathology associated with these diseases However, the different responses to BMAA that have been observed in neonatal compared to adult rats, together with the findings of epidemiological studies that exposure to environmental factors in utero or in the early stages of life may be important for the development of ALS several years later, suggested that age of exposure might be the determining factor of BMAA neurotoxicity. This study therefore specifically addresses the developmental nature of BMAA as a neurotoxin, and investigates the pathology and progressive nature of that pathology after exposure to the toxin at the most susceptible age. This study demonstrated the importance of BMAA exposure age over total BMAA dose by showing that the administration of a single neonatal dose of BMAA to rodents on postnatal day (PND) 3, 4 and 5, and not prenatally or on PND 6, 7 and 10, caused behavioural, locomotor, emotional and long-term cognitive deficits, clinical symptoms of neurodegeneration as well as pathological hallmarks of AD, PD and ALS in the central nervous system. Furthermore, the observed behavioural deficits and distribution of neuronal loss and proteinopathies in the rodent central nervous system following exposure to BMAA on PND 3, 4 and 5 (corresponding to the developing age of an infant during the third trimester of pregnancy) is consistent with that typically associated with the disruption of normal dopamine and/or serotonin signaling in the brain and the consequent alteration in normal hippocampal and striatal neurogenesis that is modulated, in part, by dopamine. The pattern of spread and rate of propagation of pathology in this neonatal rat BMAA model provided further evidence that BMAA potentially exerts its effect by acting on neurotransmitter signaling. The observed late onset of typical ALS symptoms and pathology suggest that in this BMAA model AD and/or PD related symptoms develop first, followed by the start of ALS symptoms only after the AD and/or PD neuropathological deficits have severely progressed. This study also demonstrated that BMAA exposure at different doses and at different developmental ages resulted in the development of different combinations of either AD and/or PD and/or ALS pathology and/or symptoms in rats, and it is therefore feasible that in humans the age and/or frequency of exposure as well as the BMAA dose might similarly be a major determinant of the variant of AD, PD and/or ALS that might develop in adulthood. Based on the low BMAA dose that was able to cause AD and/or PD-like neuropathological abnormalities in rats in this study, it is feasible that a pregnant human could over the course of her pregnancy, and specifically during the third trimester of pregnancy, consume sufficient BMAA to result in her unborn child developing AD and/or PD and/or ALS up to 30-50 years later. This neonatal BMAA model is the only non-transgenic rodent model that reproduces the behavioural deficits, neuropathology and clinical symptoms that are typically associated with AD, PD and ALS in humans and that, more importantly, mimics the delayed onset of disease symptoms and typical slow progression of these neurodegenerative diseases with age. It now seems very likely that BMAA is a developmental neurotoxin that, as a result of perinatal, but probably prenatal exposure, causes or contributes significantly to the development of neurodegenerative diseases in humans.
- Full Text:
- Date Issued: 2019
Carbon and nutrient storage of the Swartkops Estuary salt marsh and seagrass habitats
- Authors: Els, Jessica
- Date: 2019
- Subjects: Estuarine ecology -- South Africa -- Swartkops River Estuary , Salt marsh ecology -- South Africa -- Swartkops River Estuary Seagrasses -- Ecology Seagrasses -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42196 , vital:36634
- Description: Coastal wetlands play an important role in filtering nutrient contaminants from water bodies and are also effective carbon sinks. These systems are known as blue carbon ecosystems. Blue carbon is defined as the carbon stored and sequestered by coastal vegetated habitats such as seagrasses, salt marsh and mangroves. These habitats are being lost on a global scale due to climate change and other anthropogenic pressures. Quantifying ecosystem services provided by these habitats may lead to better conservation and restoration strategies. Research on this topic has escalated over the past decade but there are no published studies in South Africa. The aim of this study was to quantify the carbon, nitrogen, and phosphorus stocks in the above and below ground tissues of Zostera capensis, Spartina maritima, and Salicornia tegetaria — a seagrass, salt marsh grass, and salt marsh succulent. This was done in both summer and winter to understand the variability of carbon and nutrient storage. The organic carbon stock of the sediment beneath these three species was also quantified. Results showed that S. maritima, S. tegetaria, and Z. capensis stored 16 ± 2.9 Mg C. ha-1, 4.3 ± 0.7 Mg C. ha-1, and 2.1 ± 0.5 Mg C. ha-1 in their respective biomass, and 247 ± 48 Mg C. ha-1, 212 ± 44 Mg C. ha-1, and 224 ± 38 Mg C. ha-1 respectively in the sediment beneath these habitats. This was determined by elemental analysis and the loss on ignition method (LOI). The sediment made up the dominant carbon pool in the estuary and there was very little seasonal variation, however spatial variation was evident. The sediment carbon stocks were similar to the global mean for salt marsh (255 Mg C. ha-1) and greater than the global mean for seagrass (108 Mg C. ha-1). The Swartkops Estuary stored a total (biomass and sediment carbon combined) of 14 094 Mg C in the Z. capensis area of 62 ha, 25 286 Mg C in the S. maritima area of 96 ha, and 5 916 Mg C in the S. tegetaria, covering an area of 27 ha. This is significantly less than what has been found globally in estuaries, but this is largely due to the smaller area cover of these macrophytes. The amount of carbon stored per hectare is much larger in this South African system than in many international studies — possibly due to the high levels of pollution coming into the system. Nitrogen and phosphorus stocks in the plants fluctuated seasonally in relation to the nutrient input to the estuary, with the greatest stocks found in winter in Z. capensis, S. maritima, and S. tegetaria (0.42 ± 0.03 Mg N. ha-1, 1.6 ± 0.13 Mg N. ha-1, and 0.37 ± 0.02 Mg N. ha-1, respectively; and 0.4 ± 0.03 Mg P. ha-1, 1.2 ± 0.10 Mg P. ha-1 in Z. capensis and S. maritima respectively) because nutrient inputs to the system were highest in winter, however the P stocks in S. tegetaria were greatest in summer (0.35 ± 0.04 Mg P. ha-1). The reason for this difference is because of their ability to store phosphorus better than nitrogen and for longer periods of time due to luxury uptake. Salicornia tegetaria N and P stocks were also lower than the other two species, possibly due to its placement along the intertidal gradient, as it is not tidally inundated for as long as the other two species. The Z. capensis and S. maritima at Site 1 showed extremely high amounts of nitrogen in their tissues (105.3 ± 1.6 g kg-1 and 74.91 ± 4.1 g kg-1 respectively). This is due to the area being a depositional site as it was an old oyster farm and experiences little tidal flushing from the sea despite its proximity to the mouth. Nutrient ratios and N: biomass were determined as an indication of nutrient pollution. The N: biomass was low in both seasons in Z. capensis, S. maritima, and S. tegetaria (0.08, 0.02, 0.04 respectively) indicating consistant eutrophic conditions in the estuary. Plant biomass was a better indicator of nutrient pollution than epiphytes which were very low in the Swartkops Estuary and did not prove as a useful indicator of nutrient enrichment. These results can inform local management plans of the ecosystem service potential of these species and how they should be protected for future and current sustainable use as filters for nutrient pollution to keep the water quality in a better state. It also outlines the current state of blue carbon and nutrient stocks in an urban South African estuary.
- Full Text:
- Date Issued: 2019
- Authors: Els, Jessica
- Date: 2019
- Subjects: Estuarine ecology -- South Africa -- Swartkops River Estuary , Salt marsh ecology -- South Africa -- Swartkops River Estuary Seagrasses -- Ecology Seagrasses -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42196 , vital:36634
- Description: Coastal wetlands play an important role in filtering nutrient contaminants from water bodies and are also effective carbon sinks. These systems are known as blue carbon ecosystems. Blue carbon is defined as the carbon stored and sequestered by coastal vegetated habitats such as seagrasses, salt marsh and mangroves. These habitats are being lost on a global scale due to climate change and other anthropogenic pressures. Quantifying ecosystem services provided by these habitats may lead to better conservation and restoration strategies. Research on this topic has escalated over the past decade but there are no published studies in South Africa. The aim of this study was to quantify the carbon, nitrogen, and phosphorus stocks in the above and below ground tissues of Zostera capensis, Spartina maritima, and Salicornia tegetaria — a seagrass, salt marsh grass, and salt marsh succulent. This was done in both summer and winter to understand the variability of carbon and nutrient storage. The organic carbon stock of the sediment beneath these three species was also quantified. Results showed that S. maritima, S. tegetaria, and Z. capensis stored 16 ± 2.9 Mg C. ha-1, 4.3 ± 0.7 Mg C. ha-1, and 2.1 ± 0.5 Mg C. ha-1 in their respective biomass, and 247 ± 48 Mg C. ha-1, 212 ± 44 Mg C. ha-1, and 224 ± 38 Mg C. ha-1 respectively in the sediment beneath these habitats. This was determined by elemental analysis and the loss on ignition method (LOI). The sediment made up the dominant carbon pool in the estuary and there was very little seasonal variation, however spatial variation was evident. The sediment carbon stocks were similar to the global mean for salt marsh (255 Mg C. ha-1) and greater than the global mean for seagrass (108 Mg C. ha-1). The Swartkops Estuary stored a total (biomass and sediment carbon combined) of 14 094 Mg C in the Z. capensis area of 62 ha, 25 286 Mg C in the S. maritima area of 96 ha, and 5 916 Mg C in the S. tegetaria, covering an area of 27 ha. This is significantly less than what has been found globally in estuaries, but this is largely due to the smaller area cover of these macrophytes. The amount of carbon stored per hectare is much larger in this South African system than in many international studies — possibly due to the high levels of pollution coming into the system. Nitrogen and phosphorus stocks in the plants fluctuated seasonally in relation to the nutrient input to the estuary, with the greatest stocks found in winter in Z. capensis, S. maritima, and S. tegetaria (0.42 ± 0.03 Mg N. ha-1, 1.6 ± 0.13 Mg N. ha-1, and 0.37 ± 0.02 Mg N. ha-1, respectively; and 0.4 ± 0.03 Mg P. ha-1, 1.2 ± 0.10 Mg P. ha-1 in Z. capensis and S. maritima respectively) because nutrient inputs to the system were highest in winter, however the P stocks in S. tegetaria were greatest in summer (0.35 ± 0.04 Mg P. ha-1). The reason for this difference is because of their ability to store phosphorus better than nitrogen and for longer periods of time due to luxury uptake. Salicornia tegetaria N and P stocks were also lower than the other two species, possibly due to its placement along the intertidal gradient, as it is not tidally inundated for as long as the other two species. The Z. capensis and S. maritima at Site 1 showed extremely high amounts of nitrogen in their tissues (105.3 ± 1.6 g kg-1 and 74.91 ± 4.1 g kg-1 respectively). This is due to the area being a depositional site as it was an old oyster farm and experiences little tidal flushing from the sea despite its proximity to the mouth. Nutrient ratios and N: biomass were determined as an indication of nutrient pollution. The N: biomass was low in both seasons in Z. capensis, S. maritima, and S. tegetaria (0.08, 0.02, 0.04 respectively) indicating consistant eutrophic conditions in the estuary. Plant biomass was a better indicator of nutrient pollution than epiphytes which were very low in the Swartkops Estuary and did not prove as a useful indicator of nutrient enrichment. These results can inform local management plans of the ecosystem service potential of these species and how they should be protected for future and current sustainable use as filters for nutrient pollution to keep the water quality in a better state. It also outlines the current state of blue carbon and nutrient stocks in an urban South African estuary.
- Full Text:
- Date Issued: 2019
Examining the influence of extrinsic factors on herbivore assemblage composition in a southern African savanna
- Young, Cyanne, Smithwick, Erica
- Authors: Young, Cyanne , Smithwick, Erica
- Date: 2019
- Subjects: Herbivores -- Ecology , Ungulates -- Ecology Mammal populations -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44334 , vital:37154
- Description: Globally, herbivore populations have become threatened by the effects of a growing human population. This has resulted in over-hunting, habitat encroachment, fragmentation and degradation and competition leading to the replacement of wild herbivore populations with livestock. African herbivores, in particular, have experienced a severe decline in abundance and distribution, and vast conservation management efforts are underway to preserve herbivore populations and promote their growth. However, conservation management efforts sometimes have unintended consequences on the abundance and distribution of herbivores as a result of the complex interactions they have with their ecosystem. The aim of this study was to: 1) examine the drivers of herbivore distribution at the Satara section of Kruger National Park (hereafter ‘KNP’) at a landscape scale, to determine assemblage composition under the constraints of different environmental attributes; and 2) examine feeding selection by grazing herbivores of different morpho-physiological characteristics at a patch scale of differing environmental attributes. To achieve this, thirty-six experimental plots were established at three distances from water at Satara, and manipulated by mowing, mowing and fertilising or fertilising only over the course of a year, to account for seasonal effects. Each plot was fitted with a camera trap which ran for five weeks in each sampling season, and the data collected focussed on eleven herbivore species of differing body size, digestive strategy and feeding preference. These species were selected due to their abundance at Satara, and their representation of a variety of morpho-physiological characteristics. To achieve both aims, generalised linear models were used to determine the probability of occurrence of a functional type (for aim 1- Chapter 3), and individual species (for aim 2- Chapter 4). To construct the generalised linear models for Chapter 3, hypotheses about species’ relative distribution and abundance were developed through a literature review of forage and water availability constraints on feeding preference and body size of herbivore biomass at a landscape scale. I expected strong seasonal relationships between vegetation biomass and quality, and biomass of water-dependent herbivores with increasing distance to water. My analyses of herbivore distribution across the region confirmed broad-scale descriptions of interactions between forage requirements and water availability, across a set of species which differ in functional traits, at a landscape scale. In Chapter 4, trends in probability of occurrence by seven grazing herbivore species were determined using camera trap data at a patch scale. My results showed that season was a major determinant of species distribution, especially those which are not obligate grazers or feed exclusively in the 0.5 km to 2 km zone from water. I found that most selective feeding occurred in the late wet season when water would be more evenly distributed across the landscape and forage resources close to water would have had the chance to recover from depletion as a result of dry season use. The collective efforts of this study show that distance from water was a critical determinant of herbivore distribution across the landscape, and that forage utilisation by small mixed-feeders and large grazers in particular, altered significantly across seasons. This has important implications for the provision of artificial water, given that foraging pressure is increased closer to water. Landscape heterogeneity needs to be maintained through efficient water provision, to allow areas of forage reserve to maintained in the dry season, where species are constrained by water availability and forage quality and quantity.
- Full Text:
- Date Issued: 2019
- Authors: Young, Cyanne , Smithwick, Erica
- Date: 2019
- Subjects: Herbivores -- Ecology , Ungulates -- Ecology Mammal populations -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44334 , vital:37154
- Description: Globally, herbivore populations have become threatened by the effects of a growing human population. This has resulted in over-hunting, habitat encroachment, fragmentation and degradation and competition leading to the replacement of wild herbivore populations with livestock. African herbivores, in particular, have experienced a severe decline in abundance and distribution, and vast conservation management efforts are underway to preserve herbivore populations and promote their growth. However, conservation management efforts sometimes have unintended consequences on the abundance and distribution of herbivores as a result of the complex interactions they have with their ecosystem. The aim of this study was to: 1) examine the drivers of herbivore distribution at the Satara section of Kruger National Park (hereafter ‘KNP’) at a landscape scale, to determine assemblage composition under the constraints of different environmental attributes; and 2) examine feeding selection by grazing herbivores of different morpho-physiological characteristics at a patch scale of differing environmental attributes. To achieve this, thirty-six experimental plots were established at three distances from water at Satara, and manipulated by mowing, mowing and fertilising or fertilising only over the course of a year, to account for seasonal effects. Each plot was fitted with a camera trap which ran for five weeks in each sampling season, and the data collected focussed on eleven herbivore species of differing body size, digestive strategy and feeding preference. These species were selected due to their abundance at Satara, and their representation of a variety of morpho-physiological characteristics. To achieve both aims, generalised linear models were used to determine the probability of occurrence of a functional type (for aim 1- Chapter 3), and individual species (for aim 2- Chapter 4). To construct the generalised linear models for Chapter 3, hypotheses about species’ relative distribution and abundance were developed through a literature review of forage and water availability constraints on feeding preference and body size of herbivore biomass at a landscape scale. I expected strong seasonal relationships between vegetation biomass and quality, and biomass of water-dependent herbivores with increasing distance to water. My analyses of herbivore distribution across the region confirmed broad-scale descriptions of interactions between forage requirements and water availability, across a set of species which differ in functional traits, at a landscape scale. In Chapter 4, trends in probability of occurrence by seven grazing herbivore species were determined using camera trap data at a patch scale. My results showed that season was a major determinant of species distribution, especially those which are not obligate grazers or feed exclusively in the 0.5 km to 2 km zone from water. I found that most selective feeding occurred in the late wet season when water would be more evenly distributed across the landscape and forage resources close to water would have had the chance to recover from depletion as a result of dry season use. The collective efforts of this study show that distance from water was a critical determinant of herbivore distribution across the landscape, and that forage utilisation by small mixed-feeders and large grazers in particular, altered significantly across seasons. This has important implications for the provision of artificial water, given that foraging pressure is increased closer to water. Landscape heterogeneity needs to be maintained through efficient water provision, to allow areas of forage reserve to maintained in the dry season, where species are constrained by water availability and forage quality and quantity.
- Full Text:
- Date Issued: 2019
Isolation and characterisation of a channel inhibitor from Bunodosoma capense
- Authors: Van Losenoord, Wynand
- Date: 2019
- Subjects: Bioactive compounds , Potassium channels Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44134 , vital:37114
- Description: Voltage gated ion channels have recently become a subject of investigation as possible pharmaceutical targets. Research has linked the activity of ion channels directly to antiinflammatory pathways, energy homeostasis, cancer proliferation and painful diabetic neuropathy. Sea anemones secrete a diverse array of bioactive compounds including potassium and sodium channel inhibitors. A novel sodium channel inhibitor (molecular mass of 4619.7 ± 0.6 Da) with a predicted sequence: CLCNSDGPSV RGNTLSGILW LAGCPSGWHN CKKHKPTIGW CCK was isolated from Bunodosoma capense using a modified stimulation technique to induce the secretion of the neurotoxin rich mucus confirmed by an Artemia nauplii swimming assay. The peptide purification combined size-exclusion and reverse-phase high performance liquid chromatography. A thallium-based ion flux assay confirmed the presence of a sodium channel inhibitor and purity was determined using a modified tricine SDS-PAGE system. The peptide isolated indicated a tight conformation with the presence of multiple disulfide bonds in a cystine knot conformation. An IC50 value of 26 nM was determined for sodium channel inhibition on MCF-7 cells, indicating increased toxicity in comparison to sodium channel inhibitors previously isolated from Bunodosoma species.
- Full Text:
- Date Issued: 2019
- Authors: Van Losenoord, Wynand
- Date: 2019
- Subjects: Bioactive compounds , Potassium channels Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44134 , vital:37114
- Description: Voltage gated ion channels have recently become a subject of investigation as possible pharmaceutical targets. Research has linked the activity of ion channels directly to antiinflammatory pathways, energy homeostasis, cancer proliferation and painful diabetic neuropathy. Sea anemones secrete a diverse array of bioactive compounds including potassium and sodium channel inhibitors. A novel sodium channel inhibitor (molecular mass of 4619.7 ± 0.6 Da) with a predicted sequence: CLCNSDGPSV RGNTLSGILW LAGCPSGWHN CKKHKPTIGW CCK was isolated from Bunodosoma capense using a modified stimulation technique to induce the secretion of the neurotoxin rich mucus confirmed by an Artemia nauplii swimming assay. The peptide purification combined size-exclusion and reverse-phase high performance liquid chromatography. A thallium-based ion flux assay confirmed the presence of a sodium channel inhibitor and purity was determined using a modified tricine SDS-PAGE system. The peptide isolated indicated a tight conformation with the presence of multiple disulfide bonds in a cystine knot conformation. An IC50 value of 26 nM was determined for sodium channel inhibition on MCF-7 cells, indicating increased toxicity in comparison to sodium channel inhibitors previously isolated from Bunodosoma species.
- Full Text:
- Date Issued: 2019
The characterization of the interaction between Streptococcus pneumoniae PspC and Homo sapiens pIgR
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
- Authors: Steyn, Sheldon
- Date: 2019
- Subjects: Streptococcus pneumoniae , Human evolution Microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44001 , vital:37091
- Description: Streptococcus pneumoniae is a commensal bacterium in the human nasopharyngeal tract and is known to cause severe respiratory related diseases in humans. The pneumococcal surface protein C (PspC) has been demonstrated to interact with human polymeric immunoglobulin receptor (pIgR) and its free form secretory component (SC). S. pneumoniae utilizes the pIgR recycling mechanism to bypass the nasopharyngeal epithelial barrier of the host through the PspC-pIgR interaction. Studies have shown the YPT motifs in PspC R domains to be involved in this interaction (Hammerschmidt et al., 2000). The exact amino acid sequences in pIgR/SC have not yet been elucidated but Elm et al., (2004), Lu et al., (2003) and Venables et al., (2013) have demonstrated that Ig-like domains 3 and 4 of SC are mutually critical in this interaction. Mutagenesis studies were conducted to give insight into regions of these domains responsible for this interaction. In order to select possible candidates for mutagenesis, homology modelling, protein-protein docking and multiple sequence alignments were performed. PspC-SC interaction is human specific (Hammerschmidt et al., 2000) and the conservation between known species was used to select amino acids located on highly variable loop regions of the SC molecule. Amino acids Ser257, Asp312 and Gln373 were suggested by previous studies and investigated in this study. Protein-protein docking was performed with Cluspro 2.0 and Haddock 2.2 webservers. The docking results, coupled with conservation information resulted in Arg304 also being selected for investigation. Additional candidates were identified for future studies. Point mutations of the selected amino acids were introduced with overlap PCR and confirmed by DNA sequencing. The SC-D3D4 proteins were expressed in vitro and refolded by an on-column method developed by Venables et al., (2013). The Biorad ProteOn™ XPR36 protein interaction array system at Rhodes University was utilized for measuring the effects of the SC-D3D4 mutations on affinity for PspC-R1R2. The affinities of expressed SC-D3D4 mutants for PspC-R1R2 were compared to the wild type (WT) SC-D3D4 in concentration dependent kinetic analyses. The KD values for WT SC-D3D4 and Ser257, Arg304, Asp312 and Gln373 mutations were 1.4, 2.9, 4.1, 2.0, and 2.1 μM, respectively. It was concluded that these mutations had no impact on the affinity of SC-D3D4 with PspC-R1R2 and therefore probably excludes these four residues as interaction motifs for PspC.
- Full Text:
- Date Issued: 2019
Behavioural flexibility in an endangered seabird during current changes
- Authors: Traisnel, Gwendoline
- Date: 2019
- Subjects: Penguins -- South Africa , Penguins -- Behavior Sea birds -- Behavior Sea birds -- Ecology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43800 , vital:37048
- Description: Penguins spend a large part of their life cycle at sea and are amongst the most threatened seabirds as they suffer high mortality and have low reproductive success. Across the world, many populations are currently declining despite the constant development of conservation actions. The lack of information at the individual level reduces the understanding of individual variability and its potential role in the population dynamics of these vulnerable species. For example, long-lived species are characterised by substantial individual heterogeneity in their contribution to the overall population dynamic that should be understood when considering the implemention of conservation policies. This thesis explored some of the primary mechanisms behind inter-individual differences in behaviour and breeding success in the endangered African penguin Spheniscus demersus. On Bird island (Algoa Bay), nest defence behaviours were investigated on adults brooding chicks 1-3 weeks-old and chicks were measured at regular intervals (every 5 days) to assess their growth rate, a proxy for breeding success in this species. All adults were sexed and implanted with a passive integrated transponder which was used for individual identification. In this species, males are usually larger than females and have a higher survival rates both as juveniles and as adults. A subsample of them was equipped with tracking devices (GPSs and Time Depth Recorders), sometimes over consecutive foraging trips and across years. Finally, mate and nest fidelity were investigated to understand the drivers and consequences of this trait in that population. Breeding success was linked to nest defence behaviours, with bolder birds generally showing lower breeding success. This relation could not, however, be explained by differences in foraging strategies. Males were generally bolder than females when defending the nests, but their foraging behaviour did not vary with their personality. They generally had lower foraging effort than females. By contrast, bolder females performed more sinuous path, more wiggles and travelled larger vertical distances than shyer ones. Overall, females were more flexible than males over consecutive trips, suggesting that they probably adjust their behaviours to the offspring needs in this species. However, no sex difference in behavioural flexibility between sexes was visible across years, indicating that environmental variability may equally impact females and males’ behaviour over such time-scale. Generally, consistency was time-scale dependent as penguins increased their foraging flexibility across years, potentially adjusting to the variability of the environment. Interestingly, foraging consistency over consecutive trips increased during years of poor environmental conditions, and individuals with consistent foraging strategies were more successful than more flexible individuals when resources were extremely scarce. Finally, while nest and mate fidelity were high in this species, individuals that changed nest/partners, improved their breeding outcome. Particularly, after low breeding success females were more likely to change nest site and thereby partner to possibly improve their fitness. The potential biased adult sex ratio towards males in this population may facilitate changes in females which may have more partners available to re-mate than males. The present thesis reveals the existence of individual differences in behaviour and breeding success which relate to personality in penguins. These findings highlight the importance to integrate individual variability to predict future population dynamics in the context of global changes to understand the resilience and vulnerability of the species.
- Full Text:
- Date Issued: 2019
- Authors: Traisnel, Gwendoline
- Date: 2019
- Subjects: Penguins -- South Africa , Penguins -- Behavior Sea birds -- Behavior Sea birds -- Ecology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43800 , vital:37048
- Description: Penguins spend a large part of their life cycle at sea and are amongst the most threatened seabirds as they suffer high mortality and have low reproductive success. Across the world, many populations are currently declining despite the constant development of conservation actions. The lack of information at the individual level reduces the understanding of individual variability and its potential role in the population dynamics of these vulnerable species. For example, long-lived species are characterised by substantial individual heterogeneity in their contribution to the overall population dynamic that should be understood when considering the implemention of conservation policies. This thesis explored some of the primary mechanisms behind inter-individual differences in behaviour and breeding success in the endangered African penguin Spheniscus demersus. On Bird island (Algoa Bay), nest defence behaviours were investigated on adults brooding chicks 1-3 weeks-old and chicks were measured at regular intervals (every 5 days) to assess their growth rate, a proxy for breeding success in this species. All adults were sexed and implanted with a passive integrated transponder which was used for individual identification. In this species, males are usually larger than females and have a higher survival rates both as juveniles and as adults. A subsample of them was equipped with tracking devices (GPSs and Time Depth Recorders), sometimes over consecutive foraging trips and across years. Finally, mate and nest fidelity were investigated to understand the drivers and consequences of this trait in that population. Breeding success was linked to nest defence behaviours, with bolder birds generally showing lower breeding success. This relation could not, however, be explained by differences in foraging strategies. Males were generally bolder than females when defending the nests, but their foraging behaviour did not vary with their personality. They generally had lower foraging effort than females. By contrast, bolder females performed more sinuous path, more wiggles and travelled larger vertical distances than shyer ones. Overall, females were more flexible than males over consecutive trips, suggesting that they probably adjust their behaviours to the offspring needs in this species. However, no sex difference in behavioural flexibility between sexes was visible across years, indicating that environmental variability may equally impact females and males’ behaviour over such time-scale. Generally, consistency was time-scale dependent as penguins increased their foraging flexibility across years, potentially adjusting to the variability of the environment. Interestingly, foraging consistency over consecutive trips increased during years of poor environmental conditions, and individuals with consistent foraging strategies were more successful than more flexible individuals when resources were extremely scarce. Finally, while nest and mate fidelity were high in this species, individuals that changed nest/partners, improved their breeding outcome. Particularly, after low breeding success females were more likely to change nest site and thereby partner to possibly improve their fitness. The potential biased adult sex ratio towards males in this population may facilitate changes in females which may have more partners available to re-mate than males. The present thesis reveals the existence of individual differences in behaviour and breeding success which relate to personality in penguins. These findings highlight the importance to integrate individual variability to predict future population dynamics in the context of global changes to understand the resilience and vulnerability of the species.
- Full Text:
- Date Issued: 2019
An assessment of the social ecological system of Mabira forest and environs: implications for vulnerability to climate variability
- Authors: Jjagwe, Aisha
- Date: 2019
- Subjects: Climate hazards
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10948/44726 , vital:38163
- Description: Tropical forests are attracting attention in climate change debates considering the fundamental role they play as carbon sinks. Mabira Central Forest Reserve (CFR) found in the Lake Victoria basin region and of significance in achieving the Sustainable Development Goals. It has however undergone drastic degradation since the 1970s and its social economic ecological and environmental functions are at risk. The present study assessed the Social Ecological System (SES) of Mabira CFR and environs as well as the implications for vulnerability to climate variability. It focused on; i) assessment of the spatial temporal changes of Mabira CFR; to which Landsat images of 1975, 1986, 2000 and 2015 were used in combination with ground truthing for a successful classification of land use/cover types. ii) Determine the implications of land use/cover types and forest management options for above ground biomass (AGB) and soil organic carbon (SOC); here Velle, (1995) allometric equation was adopted for the AGB while the Walkley and Black (1934) was used to determine soil organic carbon iii) Determine the implications of land use cover change for livelihood and vulnerability to climate change impacts; to this the Social Ecological systems framework by Ostrom (2009) was adopted to understand the vulnerability implications for land use cover change (LUCC) and Climate variability in a forest based community. The study reveals that heavy deforestation and degradation continue to pose threats to Mabira CFR and environs. Major drivers of LUCC are: population expansion, loss of soil fertility, poor agricultural practices, establishment of roadside markets, industrialization and unclear forestry boundary. Findings indicate that although forest comprised the biggest coverage between 1975 and 2000, it has faced massive reduction between 2000 and 2015. Major forest conversions have been to subsistence farming (5.94%). The implications of LUCC are reflected in; the exposure of soils to degradation as seen from deforestation; soil erosion; carbon sequestration and climate variability constraining livelihoods. AGB and carbon was found highest in the strict nature reserve where on average the parameters noted above were found to be bigger. The recreation buffer had less carbon compared to the strict nature reserve; however the production zone, which had scattered trees with smaller parameters, registered the lowest average total AGB and carbon. Results indicate a perfectly strong relationship between the AGB and carbon variables. Results also indicate that approximately 6,771092.344 tonnes are sunk in the strict nature reserve. SOC analyzed based on the soil carbon percentage content. In terms of soil depth, the 0-10cm and 10-20cm soil layers had relatively similar variations of least square means for carbon than at 20-30cm soil layer. The highest SOC was observed in the soil surface of 0-10 cm depth, with the highest mean of 2.78 % across all the management zones. The amount of soil organic matter also varied with land use /cover types. Study findings reveal that LUCC and land management have a direct influence on soil organic carbon accumulation. Results indicate that LUCC implications for AGB and SOC as well as climate variability lead to livelihood vulnerability. Climate hazards experienced have affected SES, temperature variation range between 1oC -2oC. These variations are likely to increase vulnerability. This study recommends mapping of LUCC to identify priority areas for intervention. Priority should be given to reducing deforestation and restore degraded areas. Future research should focus on building adaptive capacity for forest based communities to mitigate climate change, improving forest tenure as a strategy for climate change impacts, integrating climate change into forest policy reviews.
- Full Text:
- Date Issued: 2019
- Authors: Jjagwe, Aisha
- Date: 2019
- Subjects: Climate hazards
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10948/44726 , vital:38163
- Description: Tropical forests are attracting attention in climate change debates considering the fundamental role they play as carbon sinks. Mabira Central Forest Reserve (CFR) found in the Lake Victoria basin region and of significance in achieving the Sustainable Development Goals. It has however undergone drastic degradation since the 1970s and its social economic ecological and environmental functions are at risk. The present study assessed the Social Ecological System (SES) of Mabira CFR and environs as well as the implications for vulnerability to climate variability. It focused on; i) assessment of the spatial temporal changes of Mabira CFR; to which Landsat images of 1975, 1986, 2000 and 2015 were used in combination with ground truthing for a successful classification of land use/cover types. ii) Determine the implications of land use/cover types and forest management options for above ground biomass (AGB) and soil organic carbon (SOC); here Velle, (1995) allometric equation was adopted for the AGB while the Walkley and Black (1934) was used to determine soil organic carbon iii) Determine the implications of land use cover change for livelihood and vulnerability to climate change impacts; to this the Social Ecological systems framework by Ostrom (2009) was adopted to understand the vulnerability implications for land use cover change (LUCC) and Climate variability in a forest based community. The study reveals that heavy deforestation and degradation continue to pose threats to Mabira CFR and environs. Major drivers of LUCC are: population expansion, loss of soil fertility, poor agricultural practices, establishment of roadside markets, industrialization and unclear forestry boundary. Findings indicate that although forest comprised the biggest coverage between 1975 and 2000, it has faced massive reduction between 2000 and 2015. Major forest conversions have been to subsistence farming (5.94%). The implications of LUCC are reflected in; the exposure of soils to degradation as seen from deforestation; soil erosion; carbon sequestration and climate variability constraining livelihoods. AGB and carbon was found highest in the strict nature reserve where on average the parameters noted above were found to be bigger. The recreation buffer had less carbon compared to the strict nature reserve; however the production zone, which had scattered trees with smaller parameters, registered the lowest average total AGB and carbon. Results indicate a perfectly strong relationship between the AGB and carbon variables. Results also indicate that approximately 6,771092.344 tonnes are sunk in the strict nature reserve. SOC analyzed based on the soil carbon percentage content. In terms of soil depth, the 0-10cm and 10-20cm soil layers had relatively similar variations of least square means for carbon than at 20-30cm soil layer. The highest SOC was observed in the soil surface of 0-10 cm depth, with the highest mean of 2.78 % across all the management zones. The amount of soil organic matter also varied with land use /cover types. Study findings reveal that LUCC and land management have a direct influence on soil organic carbon accumulation. Results indicate that LUCC implications for AGB and SOC as well as climate variability lead to livelihood vulnerability. Climate hazards experienced have affected SES, temperature variation range between 1oC -2oC. These variations are likely to increase vulnerability. This study recommends mapping of LUCC to identify priority areas for intervention. Priority should be given to reducing deforestation and restore degraded areas. Future research should focus on building adaptive capacity for forest based communities to mitigate climate change, improving forest tenure as a strategy for climate change impacts, integrating climate change into forest policy reviews.
- Full Text:
- Date Issued: 2019
Testing potential groundwater reservoir connectivity using isotopes in the south-central Karoo region
- Authors: Dlakavu, Sinazo
- Date: 2019
- Subjects: Groundwater -- South Africa -- Karoo , Hydrogeology -- South Africa Water-supply -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39447 , vital:35248
- Description: Documenting areas with natural groundwater reservior connectivity using isotopes before the anticipated shale gas development in the Karoo Basin of South Africa could contribute to developing legislative framework for hydraulic fracturing. In this study, groundwater dynamics (primarily connectivity between old/deep and low temperature modern/shallow (<25°C) groundwater) are studied using isotopes (14C, δ18O-δ2H, 3H, and δ13C) in conjunction with geochemical parameters (sampling depth (masl) and (mbgl), temperature (°C), Electrical Conductivity (EC) (μS/m) and sustainable yield (l/s)). Previous groundwater studies conducted in the Karoo Basin suggest that 14C (pMC) has the least overlap among isotope signature constraints between the different aquifer/groundwater groups. The outcomes of 14C analysis for this study suggest that one groundwater sample is an old/deep groundwater sample (<53 pMC), and that three groundwater samples are composed of shallow/young groundwater mixed with old/deep groundwater (<74 pMC). These four relatively older samples have calculated 14C ages ≥ 1700 years and were collected from boreholes that are north-east of the Cape Mountains (~50 km). The position of these samples suggests that deep-seated faults within the Cape Mountains and the basement of the southern Karoo Basin act as preferential pathways for deep groundwater migration (as is consistent with existing deep geophysical data) to shallower depths (<60 mbgl) where it cools and/or mixes with low temperature groundwater (<25°C). Three more groundwater samples were found to match the relatively old calculated 14C ages (≥ 1700 years) of the groundwater samples collected close to the Cape Mountains even though they have modern 14C (pMC) concentrations (>74 pMC). This implies that adjusting the 14C content in Dissolved Inorganic Carbon (DIC) based on its dilution by 14C free carbonates is influential in controlling the mixed groundwater ages, and that relatively older groundwater occurs at shallow depths in other parts of the study area possibly due to linked fault systems between deep and shallow aquifers. δ18O-δ2H relationships for the sampled groundwater suggest that groundwater samples collected within the main drainage of the Great Fish River plot close to the Global Meteoric Water Line (GMWL) indicating that the recharge water to this groundwater does not experience significant evaporation. The average isotope composition of the recharging water for the all of the sampled groundwater is -7.90 ‰ and -46.72 ‰ for δ18O and δ2H, respectively. This result plots halfway between rainwater 18O-2H relationship lines for the Indian Ocean and the Atlantic Ocean. This suggests that the rainwater from which the sampled groundwater was derived from evolved from both the Indian and Atlantic Ocean waters.
- Full Text:
- Date Issued: 2019
- Authors: Dlakavu, Sinazo
- Date: 2019
- Subjects: Groundwater -- South Africa -- Karoo , Hydrogeology -- South Africa Water-supply -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39447 , vital:35248
- Description: Documenting areas with natural groundwater reservior connectivity using isotopes before the anticipated shale gas development in the Karoo Basin of South Africa could contribute to developing legislative framework for hydraulic fracturing. In this study, groundwater dynamics (primarily connectivity between old/deep and low temperature modern/shallow (<25°C) groundwater) are studied using isotopes (14C, δ18O-δ2H, 3H, and δ13C) in conjunction with geochemical parameters (sampling depth (masl) and (mbgl), temperature (°C), Electrical Conductivity (EC) (μS/m) and sustainable yield (l/s)). Previous groundwater studies conducted in the Karoo Basin suggest that 14C (pMC) has the least overlap among isotope signature constraints between the different aquifer/groundwater groups. The outcomes of 14C analysis for this study suggest that one groundwater sample is an old/deep groundwater sample (<53 pMC), and that three groundwater samples are composed of shallow/young groundwater mixed with old/deep groundwater (<74 pMC). These four relatively older samples have calculated 14C ages ≥ 1700 years and were collected from boreholes that are north-east of the Cape Mountains (~50 km). The position of these samples suggests that deep-seated faults within the Cape Mountains and the basement of the southern Karoo Basin act as preferential pathways for deep groundwater migration (as is consistent with existing deep geophysical data) to shallower depths (<60 mbgl) where it cools and/or mixes with low temperature groundwater (<25°C). Three more groundwater samples were found to match the relatively old calculated 14C ages (≥ 1700 years) of the groundwater samples collected close to the Cape Mountains even though they have modern 14C (pMC) concentrations (>74 pMC). This implies that adjusting the 14C content in Dissolved Inorganic Carbon (DIC) based on its dilution by 14C free carbonates is influential in controlling the mixed groundwater ages, and that relatively older groundwater occurs at shallow depths in other parts of the study area possibly due to linked fault systems between deep and shallow aquifers. δ18O-δ2H relationships for the sampled groundwater suggest that groundwater samples collected within the main drainage of the Great Fish River plot close to the Global Meteoric Water Line (GMWL) indicating that the recharge water to this groundwater does not experience significant evaporation. The average isotope composition of the recharging water for the all of the sampled groundwater is -7.90 ‰ and -46.72 ‰ for δ18O and δ2H, respectively. This result plots halfway between rainwater 18O-2H relationship lines for the Indian Ocean and the Atlantic Ocean. This suggests that the rainwater from which the sampled groundwater was derived from evolved from both the Indian and Atlantic Ocean waters.
- Full Text:
- Date Issued: 2019
Chacma baboons (papio ursinus) influence zoogeomorphic processes in the Karoo through rock movement
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019