The spatial ecology and roost site selection of fledging Cape vultures (Gyps coprotheres) in the Eastern Cape, South Africa
- Martens, Francis Rae, Downs, Colleen
- Authors: Martens, Francis Rae , Downs, Colleen
- Date: 2018
- Subjects: Spatial ecology -- South Africa -- Easter , Gyps -- South Africa -- Eastern Cape Vultures -- South Africa -- Eastern Cape Birds -- Behavior -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15875 , vital:28284
- Description: The Cape Vulture (Gyps coprotheres), a southern African endemic, is a species currently listed on the IUCN Red List as “Threatened” due to its 66-81% decline over the past 50 years. South Africa and Lesotho hold 90% of the global population, which are focused at two core areas, namely northern central South Africa and eastern South Africa. This species provides important ecological services yet faces numerous anthropogenic threats. An emerging threat in the south eastern part of South Africa is that of wind energy development. Understanding the movement and roosting behaviour of the Cape Vulture may mitigate potential collisions if areas of high use are avoided. Juvenile Cape Vultures, who naturally suffer high mortality rates, are known to forage extensively over a wider landscape and as a consequence may face a greater assortment of threats. The overall aim of this study therefore was to determine the ranging and roosting behaviour of juvenile Cape Vultures in the Eastern Cape Province, South Africa. In order to achieve this aim, i) the ranging behaviour and habitat use were determined and ii) roost sites and factors that influence roost site selection were determined. Using five juvenile Cape Vultures tagged with Global Positioning System (GPS/GSM) transmitters, home range sizes, distance travelled from the nest and habitat use were determined. Home range was determined through kernel density estimates and distance travelled from the nest was determined through the Euclidean distance. Habitat use was determined by overlaying the home range size onto a merged layer of all protected areas and the National Land Cover Database of South Africa. To determine roost sites, data from the tagged vultures were split into encamped and exploratory movements using a mixture model in a cluster analysis setting. Encamped movements were associated with roost sites. Roost density was determined around the natal colony using predetermined buffer sizes and a generalised linear mixed model (GLMM) fitted to the data. Conditions considered favourable for roost sites were based on previous research conducted on cliff-nesting species and a GLMM conducted. Juveniles increased their home range progressively for the first two months, then exhibited a rapid increase in size associated with dispersal from the colony. Distance from the nest increased rapidly following the dispersal period. Protected areas and woody vegetation were areas of preferred habitat. The highest density of roosts for juveniles was located within 20 km’s from the breeding colony and decreased further away. Roost sites that were favoured for juveniles and adult birds were those that were located close to colonies, had low accessibility to terrestrial predators and were in areas of high wind speed. The orientation of the cliff into the prevailing wind direction was also a determining factor. Roosting sites and foraging areas are important spatial determinants of Cape Vulture behaviour and the identification of such areas can help with conservation management. With the additional threat of wind development in areas highly utilised, wind farms located too close to colonies could have a devastating impact on the Cape Vulture population. Therefore, this study highlights the importance of conservation buffer zones as no-go areas for wind energy development around vulture colonies.
- Full Text:
- Date Issued: 2018
- Authors: Martens, Francis Rae , Downs, Colleen
- Date: 2018
- Subjects: Spatial ecology -- South Africa -- Easter , Gyps -- South Africa -- Eastern Cape Vultures -- South Africa -- Eastern Cape Birds -- Behavior -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15875 , vital:28284
- Description: The Cape Vulture (Gyps coprotheres), a southern African endemic, is a species currently listed on the IUCN Red List as “Threatened” due to its 66-81% decline over the past 50 years. South Africa and Lesotho hold 90% of the global population, which are focused at two core areas, namely northern central South Africa and eastern South Africa. This species provides important ecological services yet faces numerous anthropogenic threats. An emerging threat in the south eastern part of South Africa is that of wind energy development. Understanding the movement and roosting behaviour of the Cape Vulture may mitigate potential collisions if areas of high use are avoided. Juvenile Cape Vultures, who naturally suffer high mortality rates, are known to forage extensively over a wider landscape and as a consequence may face a greater assortment of threats. The overall aim of this study therefore was to determine the ranging and roosting behaviour of juvenile Cape Vultures in the Eastern Cape Province, South Africa. In order to achieve this aim, i) the ranging behaviour and habitat use were determined and ii) roost sites and factors that influence roost site selection were determined. Using five juvenile Cape Vultures tagged with Global Positioning System (GPS/GSM) transmitters, home range sizes, distance travelled from the nest and habitat use were determined. Home range was determined through kernel density estimates and distance travelled from the nest was determined through the Euclidean distance. Habitat use was determined by overlaying the home range size onto a merged layer of all protected areas and the National Land Cover Database of South Africa. To determine roost sites, data from the tagged vultures were split into encamped and exploratory movements using a mixture model in a cluster analysis setting. Encamped movements were associated with roost sites. Roost density was determined around the natal colony using predetermined buffer sizes and a generalised linear mixed model (GLMM) fitted to the data. Conditions considered favourable for roost sites were based on previous research conducted on cliff-nesting species and a GLMM conducted. Juveniles increased their home range progressively for the first two months, then exhibited a rapid increase in size associated with dispersal from the colony. Distance from the nest increased rapidly following the dispersal period. Protected areas and woody vegetation were areas of preferred habitat. The highest density of roosts for juveniles was located within 20 km’s from the breeding colony and decreased further away. Roost sites that were favoured for juveniles and adult birds were those that were located close to colonies, had low accessibility to terrestrial predators and were in areas of high wind speed. The orientation of the cliff into the prevailing wind direction was also a determining factor. Roosting sites and foraging areas are important spatial determinants of Cape Vulture behaviour and the identification of such areas can help with conservation management. With the additional threat of wind development in areas highly utilised, wind farms located too close to colonies could have a devastating impact on the Cape Vulture population. Therefore, this study highlights the importance of conservation buffer zones as no-go areas for wind energy development around vulture colonies.
- Full Text:
- Date Issued: 2018
Design and development of a context sensitive rural development software application for eService provisioning
- Authors: Masikisiki, Lizo
- Date: 2018
- Subjects: Rural development Electronic commerce Computer networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15332 , vital:40366
- Description: After more than a decade since South Africa realized the importance of Information and Communication Technology (ICT) and the role it can play to deliver services, the country is still confronted by a number of challenges challenges that hinder the implementation of a fully-fledged ICT-based system in a form of electronic government to better deliver services and information. While rural development remains as one of the country’s greatest concerns, ICT is among approaches and perspectives that are recognized for not only accelerating rural development but also for providing the country’s economic growth. This research was set to investigate approaches to implement ICT solutions for rural development and service provisioning in the context of electronic government. The research focused more on the technical skills to implement such ICT systems for the benefit of rural development and e-government stakeholders that have an interest in design and development of an integrated and interoperable solution to accelerate service delivery, especially in rural communities. A mixed methods approach was used throughout the research accompanied by an evolutionary prototyping to development the desired prototype. A study was then conducted to gain an understanding of the state and the needs of rural communities to date. The results of the study yielded a number of urbanized service providers that rural dwellers need to timeously visit to consume services. Scenarios to design and develop the intended prototypes were then drawn from these results. The overall implementation of the prototypes produced an integrated platform that allows multiple disparate systems to communicate, share and use information. The qualities of the prototype are what this research recommends to relevant to stakeholders in order to implement an integrated and interoperable e-government system that elevates rural development programs and service delivery.
- Full Text:
- Date Issued: 2018
- Authors: Masikisiki, Lizo
- Date: 2018
- Subjects: Rural development Electronic commerce Computer networks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15332 , vital:40366
- Description: After more than a decade since South Africa realized the importance of Information and Communication Technology (ICT) and the role it can play to deliver services, the country is still confronted by a number of challenges challenges that hinder the implementation of a fully-fledged ICT-based system in a form of electronic government to better deliver services and information. While rural development remains as one of the country’s greatest concerns, ICT is among approaches and perspectives that are recognized for not only accelerating rural development but also for providing the country’s economic growth. This research was set to investigate approaches to implement ICT solutions for rural development and service provisioning in the context of electronic government. The research focused more on the technical skills to implement such ICT systems for the benefit of rural development and e-government stakeholders that have an interest in design and development of an integrated and interoperable solution to accelerate service delivery, especially in rural communities. A mixed methods approach was used throughout the research accompanied by an evolutionary prototyping to development the desired prototype. A study was then conducted to gain an understanding of the state and the needs of rural communities to date. The results of the study yielded a number of urbanized service providers that rural dwellers need to timeously visit to consume services. Scenarios to design and develop the intended prototypes were then drawn from these results. The overall implementation of the prototypes produced an integrated platform that allows multiple disparate systems to communicate, share and use information. The qualities of the prototype are what this research recommends to relevant to stakeholders in order to implement an integrated and interoperable e-government system that elevates rural development programs and service delivery.
- Full Text:
- Date Issued: 2018
Tolerance of salt marsh ecotone species to salinity and inundation
- Authors: Matabane, Rebotile
- Date: 2018
- Subjects: Geobiology , Plant ecology Plant ecophysiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22409 , vital:29967
- Description: Ecophysiology studies help understand and predict the response of coastal ecosystems to changes in environmental factors and complement modelling and mapping studies that often do not take into account the physiological tolerances of the biota. Along the South African coastline predicted sea level rise will shift the tidal front and result in larger submerged areas. The frequency and magnitude of inundation and subsequent salinity stress is expected to influence the survival and distribution of salt marsh. An understanding of the effects of sea level rise on plant growth and survival is required to predict, manage and adapt to climate change. The aim of this study was to investigate the response of the salt marsh ecotone species Disphyma crassifolium (L.) L. Bol. to salinity and submergence stress and to measure in situ spatial and temporal changes in vegetation cover and its environmental drivers in the Swartkops Estuary in South Africa.Three greenhouse experiments assessed morphological and physiological responses to salinity and inundation treatments on D. crassifolium. The first experiment used three inundation levels (dry, tidal and waterlogged) and five salinity treatments (0, 8, 18, 35 and 45 ppt) and ran for six weeks. The second experiment also had three inundation levels (dry, waterlogged and completely submerged) and five salinity treatments (0, 8, 18, 35 and 45 ppt) and ran for 12 weeks. The third experiment investigated the response of a narrower range of salinity treatments under dry conditions only; namely 0, 5, 10, 15, 20, 25, 30 and 35 ppt and ran for seven weeks. Experiment 1 showed that D. crassifolium growth decreased with an increase in salinity. Optimum growth occurred at lower salinity treatments of 0 to 18 ppt under dry conditions. Plant height and leaf succulence was the highest at 0 ppt (12.4 ± 1.2 cm and 94.9 ± 0.6 % respectively). The number of leaves produced were the highest at 0 ppt (47.7 ± 8.9 number of leaves) and 8 ppt (59.6 ± 6.3 number of leaves). The root/shoot ratio for dry treatment plants was significantly lower (p < 0.005, n=12) than that of waterlogged and tidal-treated plants. This was as a result of more leaves being produced in dry treatments. In Experiment 2 D. crassifolium plants died after one month of submergence regardless of the salinity. Once again optimum growth occurred at salinity of 0 to 18 ppt under the dry treatment. Within the waterlogged treatment, 0 and 8 ppt treated plants developed adventitious roots and started flowering after two weeks.The electrolyte leakage increased with salinity, however the waterlogged plants had significantly higher electrolyte leakage compare to the dry treated plants. Within the waterlogged treatment electrolyte leakage was at the highest at 18 ppt (36.5 ± 4.2 %) and lowest at 0 ppt (26.1 ± 3.3 %). Photosynthetic pigments showed significant difference across the two inundation states. However, chlorophyll and carotenoids concentrations did not differ significantly with an increase in salinity in each treatment. D. crassifolium tolerated stress through accumulation of solutes that increased in concentration with salinity treatment. The proline concentration ranged between 23.1 to 102 mM while the glycinebetaine concentration ranged between 36.6 and 120 mM. Experiment 3 showed that growth was highest at salinity < 20 ppt. The highest growth based on plant height was measured at 0 and 10 ppt. Spatial and temporal changes in the salt marsh terrestrial boundary was investigated in situ at two sites in the Swartkops Estuary using three line transects per site extending from the terrestrial boundary to the supratidal salt marsh. Plant cover abundance was measured seasonally along with sediment moisture content, electrical conductivity, redox potential, organic content and sediment particle size. There were five sampling trips between April 2016 to July 2017, representing autumn, winter and summer. The transects at Sites 1 and 2 were divided into three zones; a Drosanthemum zone (dominated by Drosanthemum parvifolium (Haw.) Schwantes at the beginning of the transect), a Sarcocornia zone (in the middle of the transect and dominated by Sarcocornia pillanssii (Moss) A.J. Scott) and a Disphyma zone at the end of the transect in the supratidal marsh (dominated by Disphyma crassifolium). There was no significant seasonal change in vegetation cover except in Site 1 during Winter 2016 when Isolepis sp. appeared and was dominant in the middle of the transects. Sediment assessed from each of the zones showed physicochemical ranges within the typical ecotone sediment characteristics. Moisture content ranged between 0.6 and 30.9 % at Site 1 and between 3 and 33.8 % at Site 2. Electrical conductivity ranged between 0.9 and 10.2 mS cm-1 at Site 1 and between 1.4 and 17.8 mS cm-1 at Site 2. Organic content ranged between 1.9 and 16 % at Site 1 and between 3.9 and 16.3 % at Site 2. Redox potential ranged between 208 and 406.7 mV at Site 1 and between 202.7 and 389.67 mV at Site 2. Sediment particle size consisted of sand (>70%), silt (>15%) and clay (<10%). The aim of this study was to provide insight on the effects of salinity and inundation on the morphology and physiology of D. crassifolium occurring in the salt marsh terrestrial boundary and to assess its spatial and temporal changes over time. The research suggests that D. crassifolium is more sensitive to inundation than salinity. Furthermore the succulent was found in the field to be dominant in conditions which the glasshouse experiments showed to be its optimum growth. That is, in dry sediments with salinity of < 18 ppt. Therefore, if these conditions change (sediment moisture and salinity), the cover abundance of D. crassifolium could significantly change in the field.
- Full Text:
- Date Issued: 2018
- Authors: Matabane, Rebotile
- Date: 2018
- Subjects: Geobiology , Plant ecology Plant ecophysiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22409 , vital:29967
- Description: Ecophysiology studies help understand and predict the response of coastal ecosystems to changes in environmental factors and complement modelling and mapping studies that often do not take into account the physiological tolerances of the biota. Along the South African coastline predicted sea level rise will shift the tidal front and result in larger submerged areas. The frequency and magnitude of inundation and subsequent salinity stress is expected to influence the survival and distribution of salt marsh. An understanding of the effects of sea level rise on plant growth and survival is required to predict, manage and adapt to climate change. The aim of this study was to investigate the response of the salt marsh ecotone species Disphyma crassifolium (L.) L. Bol. to salinity and submergence stress and to measure in situ spatial and temporal changes in vegetation cover and its environmental drivers in the Swartkops Estuary in South Africa.Three greenhouse experiments assessed morphological and physiological responses to salinity and inundation treatments on D. crassifolium. The first experiment used three inundation levels (dry, tidal and waterlogged) and five salinity treatments (0, 8, 18, 35 and 45 ppt) and ran for six weeks. The second experiment also had three inundation levels (dry, waterlogged and completely submerged) and five salinity treatments (0, 8, 18, 35 and 45 ppt) and ran for 12 weeks. The third experiment investigated the response of a narrower range of salinity treatments under dry conditions only; namely 0, 5, 10, 15, 20, 25, 30 and 35 ppt and ran for seven weeks. Experiment 1 showed that D. crassifolium growth decreased with an increase in salinity. Optimum growth occurred at lower salinity treatments of 0 to 18 ppt under dry conditions. Plant height and leaf succulence was the highest at 0 ppt (12.4 ± 1.2 cm and 94.9 ± 0.6 % respectively). The number of leaves produced were the highest at 0 ppt (47.7 ± 8.9 number of leaves) and 8 ppt (59.6 ± 6.3 number of leaves). The root/shoot ratio for dry treatment plants was significantly lower (p < 0.005, n=12) than that of waterlogged and tidal-treated plants. This was as a result of more leaves being produced in dry treatments. In Experiment 2 D. crassifolium plants died after one month of submergence regardless of the salinity. Once again optimum growth occurred at salinity of 0 to 18 ppt under the dry treatment. Within the waterlogged treatment, 0 and 8 ppt treated plants developed adventitious roots and started flowering after two weeks.The electrolyte leakage increased with salinity, however the waterlogged plants had significantly higher electrolyte leakage compare to the dry treated plants. Within the waterlogged treatment electrolyte leakage was at the highest at 18 ppt (36.5 ± 4.2 %) and lowest at 0 ppt (26.1 ± 3.3 %). Photosynthetic pigments showed significant difference across the two inundation states. However, chlorophyll and carotenoids concentrations did not differ significantly with an increase in salinity in each treatment. D. crassifolium tolerated stress through accumulation of solutes that increased in concentration with salinity treatment. The proline concentration ranged between 23.1 to 102 mM while the glycinebetaine concentration ranged between 36.6 and 120 mM. Experiment 3 showed that growth was highest at salinity < 20 ppt. The highest growth based on plant height was measured at 0 and 10 ppt. Spatial and temporal changes in the salt marsh terrestrial boundary was investigated in situ at two sites in the Swartkops Estuary using three line transects per site extending from the terrestrial boundary to the supratidal salt marsh. Plant cover abundance was measured seasonally along with sediment moisture content, electrical conductivity, redox potential, organic content and sediment particle size. There were five sampling trips between April 2016 to July 2017, representing autumn, winter and summer. The transects at Sites 1 and 2 were divided into three zones; a Drosanthemum zone (dominated by Drosanthemum parvifolium (Haw.) Schwantes at the beginning of the transect), a Sarcocornia zone (in the middle of the transect and dominated by Sarcocornia pillanssii (Moss) A.J. Scott) and a Disphyma zone at the end of the transect in the supratidal marsh (dominated by Disphyma crassifolium). There was no significant seasonal change in vegetation cover except in Site 1 during Winter 2016 when Isolepis sp. appeared and was dominant in the middle of the transects. Sediment assessed from each of the zones showed physicochemical ranges within the typical ecotone sediment characteristics. Moisture content ranged between 0.6 and 30.9 % at Site 1 and between 3 and 33.8 % at Site 2. Electrical conductivity ranged between 0.9 and 10.2 mS cm-1 at Site 1 and between 1.4 and 17.8 mS cm-1 at Site 2. Organic content ranged between 1.9 and 16 % at Site 1 and between 3.9 and 16.3 % at Site 2. Redox potential ranged between 208 and 406.7 mV at Site 1 and between 202.7 and 389.67 mV at Site 2. Sediment particle size consisted of sand (>70%), silt (>15%) and clay (<10%). The aim of this study was to provide insight on the effects of salinity and inundation on the morphology and physiology of D. crassifolium occurring in the salt marsh terrestrial boundary and to assess its spatial and temporal changes over time. The research suggests that D. crassifolium is more sensitive to inundation than salinity. Furthermore the succulent was found in the field to be dominant in conditions which the glasshouse experiments showed to be its optimum growth. That is, in dry sediments with salinity of < 18 ppt. Therefore, if these conditions change (sediment moisture and salinity), the cover abundance of D. crassifolium could significantly change in the field.
- Full Text:
- Date Issued: 2018
Assessing growth response patterns of microalgae to varying environmental conditions using sediments from ephemeral wetlands
- Authors: Mazwane, Sixolile
- Date: 2018
- Subjects: Microalgae -- South Africa , Wetland conservation -- South Africa Landscape ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22398 , vital:29966
- Description: Ephemeral wetlands serve as habitats for different fauna and flora. Microalgae make up a bulk of primary production in newly inundated wetlands and have a big influence on the aquatic community structure. As ephemeral wetlands have cyclical drying and wetting phases, algal species found in these habitats have evolved adaptations (i.e. dormancy and cysts) to survive during dry periods and become productive upon inundation. Algae have been used as ecological indicators in many aquatic ecosystems including wetlands, particularly associated with water quality and with varying inundation states. Whilst temperature and water level have been shown to affect microalgal biomass independently, this study aims to assess the effects of these two factors simultaneously on microalgal biomass, species diversity and community changes. The aim of the study was to investigate microalgal dynamics using two ephemeral wetlands in the Nelson Mandela Bay Municipality. The growth response patterns of microalgal communities to varying temperatures and inundation levels through experiments using dry temporary wetland sediments was also assessed. Dry sediments were collected from two depression wetlands with different sediment characteristics (1592 and Elephant Wallow (EW)). The study consisted of replicated treatments with three different surface area: volume ratios (SA:V) (Low surface area: volume (LSAV), Medium (MSAV) and High (HSAV)), inundated with distilled water. The microcosms were placed inside a Conviron environmental growth chamber and illuminated at between 106 to 138 μmol.m-2s-1, with a 12:12 light-dark cycle at constant temperatures of 12 °C (mean winter) and 22 °C (mean summer). Physicochemical data were recorded, and biological samples were collected every 4 days over a 28-day inundation period. In the field, Electrical conductivity (EC) and pH showed a gradual increase over the inundation period. The systems were well oxygenated (6-10 mg L-1). Overall, phytoplankton biomass in the field was ~10 μg L-1 whereas benthic biomass (MPB) was significantly higher 10 – 300 mg L-1. Within the experiments, the phytoplankton biomass showed a pattern while MPB biomass increased gradually for both experiments. There were no significant (p>0.05) differences between the 1592 and EW phytoplankton biomass. However, the MPB biomass showed significant (p<0.05) differences between the two sediments (EW high, 1592 low) and the experiments, respectively. In the winter experiment, the 1592 sediment had high phytoplankton biomass compared to EW, the reverse was observed for the MPB biomass. In summer experiment, similar results were observed in terms of phytoplankton biomass. For the MPBs, 1592 had greater biomass for all treatments compared to EW. The phytoplankton community for both field samples and experiments was dominated by chlorophytes (>50 %), followed by cyanophytes and euglenophytes (with cryptophytes in summer experiment) for both field and experiments. The MPB community was dominated by bacillariophytes (55 %) and chlorophytes (25 %) in the 1592 sediments and this was also the case with EW sediments bacillariophytes (70 %), although cyanophytes (15 %) made up the remainder of the MPB community. The 1592 sediments supported higher diatom abundances under the HSAV compared to the same treatment from the EW wetland suggesting that possibly grain size or texture might be responsible. In contrast, sediments from EW under LSAV conditions showed higher diatom cell numbers possibly indicating that increased water depth has the propensity to support greater diatom assemblages compared with the same water level for sediments from 1592. The results indicate that microalgae community is influenced by sediment type more than it is by water level. From this study it was also established that microalgae were able to reemerge from their dormancy state upon inundation and that tank experiments were successful in simulating natural ephemeral wetland conditions. The findings from this study will add to the available baseline data on microalgal dynamics in the ephemeral wetlands in South Africa, especially in semi-arid areas. This information can be valuable in enhancing our understanding regarding the role of microalgae in ephemeral wetlands in order to conserve them.
- Full Text:
- Date Issued: 2018
- Authors: Mazwane, Sixolile
- Date: 2018
- Subjects: Microalgae -- South Africa , Wetland conservation -- South Africa Landscape ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22398 , vital:29966
- Description: Ephemeral wetlands serve as habitats for different fauna and flora. Microalgae make up a bulk of primary production in newly inundated wetlands and have a big influence on the aquatic community structure. As ephemeral wetlands have cyclical drying and wetting phases, algal species found in these habitats have evolved adaptations (i.e. dormancy and cysts) to survive during dry periods and become productive upon inundation. Algae have been used as ecological indicators in many aquatic ecosystems including wetlands, particularly associated with water quality and with varying inundation states. Whilst temperature and water level have been shown to affect microalgal biomass independently, this study aims to assess the effects of these two factors simultaneously on microalgal biomass, species diversity and community changes. The aim of the study was to investigate microalgal dynamics using two ephemeral wetlands in the Nelson Mandela Bay Municipality. The growth response patterns of microalgal communities to varying temperatures and inundation levels through experiments using dry temporary wetland sediments was also assessed. Dry sediments were collected from two depression wetlands with different sediment characteristics (1592 and Elephant Wallow (EW)). The study consisted of replicated treatments with three different surface area: volume ratios (SA:V) (Low surface area: volume (LSAV), Medium (MSAV) and High (HSAV)), inundated with distilled water. The microcosms were placed inside a Conviron environmental growth chamber and illuminated at between 106 to 138 μmol.m-2s-1, with a 12:12 light-dark cycle at constant temperatures of 12 °C (mean winter) and 22 °C (mean summer). Physicochemical data were recorded, and biological samples were collected every 4 days over a 28-day inundation period. In the field, Electrical conductivity (EC) and pH showed a gradual increase over the inundation period. The systems were well oxygenated (6-10 mg L-1). Overall, phytoplankton biomass in the field was ~10 μg L-1 whereas benthic biomass (MPB) was significantly higher 10 – 300 mg L-1. Within the experiments, the phytoplankton biomass showed a pattern while MPB biomass increased gradually for both experiments. There were no significant (p>0.05) differences between the 1592 and EW phytoplankton biomass. However, the MPB biomass showed significant (p<0.05) differences between the two sediments (EW high, 1592 low) and the experiments, respectively. In the winter experiment, the 1592 sediment had high phytoplankton biomass compared to EW, the reverse was observed for the MPB biomass. In summer experiment, similar results were observed in terms of phytoplankton biomass. For the MPBs, 1592 had greater biomass for all treatments compared to EW. The phytoplankton community for both field samples and experiments was dominated by chlorophytes (>50 %), followed by cyanophytes and euglenophytes (with cryptophytes in summer experiment) for both field and experiments. The MPB community was dominated by bacillariophytes (55 %) and chlorophytes (25 %) in the 1592 sediments and this was also the case with EW sediments bacillariophytes (70 %), although cyanophytes (15 %) made up the remainder of the MPB community. The 1592 sediments supported higher diatom abundances under the HSAV compared to the same treatment from the EW wetland suggesting that possibly grain size or texture might be responsible. In contrast, sediments from EW under LSAV conditions showed higher diatom cell numbers possibly indicating that increased water depth has the propensity to support greater diatom assemblages compared with the same water level for sediments from 1592. The results indicate that microalgae community is influenced by sediment type more than it is by water level. From this study it was also established that microalgae were able to reemerge from their dormancy state upon inundation and that tank experiments were successful in simulating natural ephemeral wetland conditions. The findings from this study will add to the available baseline data on microalgal dynamics in the ephemeral wetlands in South Africa, especially in semi-arid areas. This information can be valuable in enhancing our understanding regarding the role of microalgae in ephemeral wetlands in order to conserve them.
- Full Text:
- Date Issued: 2018
The evaluation of potential dietary media, measurement parameters and storage techniques for use in forensic entomotoxicology
- Mbatha, Erica Isabel Tavares Da Silva
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
The influence of landscape dis-connectivity on the structure and function of the Krom River, Eastern Cape, South Africa
- Authors: McNamara, Shaun
- Date: 2018
- Subjects: Wetland ecology -- South Africa -- Kromme River (Eastern Cape) , Alluvial fans -- South Africa -- Kromme River (Eastern Cape) , Sedimentation and deposition -- South Africa -- Kromme River (Eastern Cape) , Fluvial geomorphology -- South Africa -- Kromme River (Eastern Cape) , Soil erosion -- South Africa -- Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63198 , vital:28380
- Description: Given that a broad valley and low longitudinal slope are important pre-requisites for wetland formation in dryland environments, it has been proposed that cut-and-fill cycles are largely responsible for the geomorphic evolution of the Krom River valley-bottom wetlands. Research to support this suggestion has focused extensively on the role of phases of incision. As a result, little is known about where sediment mobilised during phases of incision is being deposited (filling phase). This study aimed to address this question to add to the understanding of how cut-and-fill cycles influence the structure and functioning of the Krom River and its wetlands. This was achieved through a reach-scale appraisal of the degree of longitudinal connectivity of the Krom River. The reach used for this appraisal contained an incised section along which the river channel exists as a large gully, and a section immediately downstream of the gully terminus where the Krom River is un-gullied, and flow is diffuse across most of the width of the valley floor. Quantification of the masses of sediment eroded and deposited within the selected reach of the Krom River during a single recent (2012) flood event revealed that the degree of longitudinal connectivity in the Krom River is generally low. During the flood, much of the sediment mobilised by the cutting of the Krom River channel was deposited immediately downstream of the gully terminus, forming a large floodout feature. Particle size analyses of core samples taken along the floodout feature showed that the coarsest fraction of previously mobilised sediment was deposited at the head of the floodout, while finer sediment fractions were deposited progressively further downstream. Field surveys revealed that the pattern of deposition within the floodout feature led to localised steepening of the studied reach of the Krom River downstream of the gully terminus. Surveys of the recently eroded gully revealed that following incision, the eroded stream bed had a lower longitudinal gradient than both the pre-erosional land surface and the regional slope of the Krom River. The results of this study suggest that floodout formation downstream of gullies may promote the transgression of geomorphic thresholds for erosion, such that the development of floodout features leads to likely initiation of new cutting phases in novel locations along the course of the Krom River. They further suggest that the Krom River is capable of intrinsic longitudinal self-recovery through ongoing cut-and-fill cycles. Finally, it would appear that the current cutting phases responsible for the “destruction” of wetlands within the system are part of a cycle that will lead to prolonged geomorphic stability, such that the system is made more suitable for the long-term re-establishment of wetlands.
- Full Text:
- Date Issued: 2018
- Authors: McNamara, Shaun
- Date: 2018
- Subjects: Wetland ecology -- South Africa -- Kromme River (Eastern Cape) , Alluvial fans -- South Africa -- Kromme River (Eastern Cape) , Sedimentation and deposition -- South Africa -- Kromme River (Eastern Cape) , Fluvial geomorphology -- South Africa -- Kromme River (Eastern Cape) , Soil erosion -- South Africa -- Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63198 , vital:28380
- Description: Given that a broad valley and low longitudinal slope are important pre-requisites for wetland formation in dryland environments, it has been proposed that cut-and-fill cycles are largely responsible for the geomorphic evolution of the Krom River valley-bottom wetlands. Research to support this suggestion has focused extensively on the role of phases of incision. As a result, little is known about where sediment mobilised during phases of incision is being deposited (filling phase). This study aimed to address this question to add to the understanding of how cut-and-fill cycles influence the structure and functioning of the Krom River and its wetlands. This was achieved through a reach-scale appraisal of the degree of longitudinal connectivity of the Krom River. The reach used for this appraisal contained an incised section along which the river channel exists as a large gully, and a section immediately downstream of the gully terminus where the Krom River is un-gullied, and flow is diffuse across most of the width of the valley floor. Quantification of the masses of sediment eroded and deposited within the selected reach of the Krom River during a single recent (2012) flood event revealed that the degree of longitudinal connectivity in the Krom River is generally low. During the flood, much of the sediment mobilised by the cutting of the Krom River channel was deposited immediately downstream of the gully terminus, forming a large floodout feature. Particle size analyses of core samples taken along the floodout feature showed that the coarsest fraction of previously mobilised sediment was deposited at the head of the floodout, while finer sediment fractions were deposited progressively further downstream. Field surveys revealed that the pattern of deposition within the floodout feature led to localised steepening of the studied reach of the Krom River downstream of the gully terminus. Surveys of the recently eroded gully revealed that following incision, the eroded stream bed had a lower longitudinal gradient than both the pre-erosional land surface and the regional slope of the Krom River. The results of this study suggest that floodout formation downstream of gullies may promote the transgression of geomorphic thresholds for erosion, such that the development of floodout features leads to likely initiation of new cutting phases in novel locations along the course of the Krom River. They further suggest that the Krom River is capable of intrinsic longitudinal self-recovery through ongoing cut-and-fill cycles. Finally, it would appear that the current cutting phases responsible for the “destruction” of wetlands within the system are part of a cycle that will lead to prolonged geomorphic stability, such that the system is made more suitable for the long-term re-establishment of wetlands.
- Full Text:
- Date Issued: 2018
Household's perceptions and determinants of participation in harvesting rangeland products :|bthe case of Dyamala community, Raymond Mhlaba Local Municipality, Eastern Cape Province, South Africa
- Authors: Mdiya, Lwandiso
- Date: 2018
- Subjects: Rangelands -- South Africa -- Eastern Cape Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9187 , vital:34303
- Description: The study reviews the household’s perceptions and determinants of sustainable products harvesting. Communal rangelands are vast natural landscapes in the form of grasslands, shrubs, woodlands, wetlands and deserts with multiple functions to the rural households. Most rural communities share boundaries and interact with rangelands for multiple socioeconomic and environmental reasons. Since most of these interactions are external to the price mechanism, the actual contribution of rangelands to communities has largely been missed. In an effort to appraise and explore the communal rangeland contribution to households, a study from Dyamala community in the Raymond Mhlaba Local Municipality under Amathole District in Eastern Cape was conducted using cross-sectional data. Descriptive results revealed that the majority of the respondents (71 percent) from the study area positively perceived communal rangelands as safety nets. however, there also emerged a fair share of challenges namely, (bad spirit, host predators, compete with arable land) leading to negative perceptions towards communal rangelands. It was also evident that, the majority of respondents from the study area use communal rangelands for fuel wood, construction poles, traditional medicine, with minor harvests of wild food (flora and fauna) and thatch grass. The results of the study also revealed that, rural people depend more on social grants for their income followed by incomes from remittances, agricultural activities and communal rangelands. However, it was established from the results that though communal rangelands provided commercial products capable of generating household income, rangeland users trading such products were receiving meagre incomes. This might be caused by the lack of institutional support to rural households thus, the low incomes received from communal rangelands. To that effect, main communal rangeland products such as, fuel wood, poles and medicine were cited as being more valuable for local domestic use than for the external market. Regression estimates further indicated that participation in communal rangeland products harvesting is more conditioned by perception-related factors as compared to socioeconomic attributes of rural households worth understanding for strategic targeting to promote their conservation. The extant literature and the study results, evidently show that communal rangelands provide a livelihood among rural households although it has a low direct household income potential. Therefore, the respondents were of the view that the use of campaigns targeting several perceptions (such as communal rangelands act as a source of medicinal plants, arable land and income etc) as suggested by the regression estimates may be very useful. The support from the extension department and further research may be necessary for purposes of quantifying harvestable rangeland products capable of enhancing rural livelihoods. Moreover, the observed low income potential of communal rangeland products suggests several technical and institutional challenges worth addressing to promote value addition of rangeland products.
- Full Text:
- Date Issued: 2018
- Authors: Mdiya, Lwandiso
- Date: 2018
- Subjects: Rangelands -- South Africa -- Eastern Cape Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9187 , vital:34303
- Description: The study reviews the household’s perceptions and determinants of sustainable products harvesting. Communal rangelands are vast natural landscapes in the form of grasslands, shrubs, woodlands, wetlands and deserts with multiple functions to the rural households. Most rural communities share boundaries and interact with rangelands for multiple socioeconomic and environmental reasons. Since most of these interactions are external to the price mechanism, the actual contribution of rangelands to communities has largely been missed. In an effort to appraise and explore the communal rangeland contribution to households, a study from Dyamala community in the Raymond Mhlaba Local Municipality under Amathole District in Eastern Cape was conducted using cross-sectional data. Descriptive results revealed that the majority of the respondents (71 percent) from the study area positively perceived communal rangelands as safety nets. however, there also emerged a fair share of challenges namely, (bad spirit, host predators, compete with arable land) leading to negative perceptions towards communal rangelands. It was also evident that, the majority of respondents from the study area use communal rangelands for fuel wood, construction poles, traditional medicine, with minor harvests of wild food (flora and fauna) and thatch grass. The results of the study also revealed that, rural people depend more on social grants for their income followed by incomes from remittances, agricultural activities and communal rangelands. However, it was established from the results that though communal rangelands provided commercial products capable of generating household income, rangeland users trading such products were receiving meagre incomes. This might be caused by the lack of institutional support to rural households thus, the low incomes received from communal rangelands. To that effect, main communal rangeland products such as, fuel wood, poles and medicine were cited as being more valuable for local domestic use than for the external market. Regression estimates further indicated that participation in communal rangeland products harvesting is more conditioned by perception-related factors as compared to socioeconomic attributes of rural households worth understanding for strategic targeting to promote their conservation. The extant literature and the study results, evidently show that communal rangelands provide a livelihood among rural households although it has a low direct household income potential. Therefore, the respondents were of the view that the use of campaigns targeting several perceptions (such as communal rangelands act as a source of medicinal plants, arable land and income etc) as suggested by the regression estimates may be very useful. The support from the extension department and further research may be necessary for purposes of quantifying harvestable rangeland products capable of enhancing rural livelihoods. Moreover, the observed low income potential of communal rangeland products suggests several technical and institutional challenges worth addressing to promote value addition of rangeland products.
- Full Text:
- Date Issued: 2018
Potential impact and host range of Pereskiophaga brasiliensis Anderson (Curculionidae): a new candidate biological control agent for the control of Pereskia aculeata Miller (Cactaceae) in South Africa
- Authors: Mdodana, Lumka Anita
- Date: 2018
- Subjects: Curculionidae -- South Africa , Cactus -- South Africa , Biological pest control agents , Alien plants-- South Africa , Pereskiophaga brasiliensis Anderson (Curculionidae) , Pereskia aculeata Miller (Cactaceae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62350 , vital:28157
- Description: Pereskia aculeata Miller (Cactaceae) is a damaging invasive alien plant in South Africa that has negative impacts to indigenous biodiversity and ecosystem functioning. Mechanical and chemical control are not effective against P. aculeata so biological control is considered the only viable option. Two biological control agents, the leaf-feeding beetle Phenrica guerini Bechyne (Chrysomelidae) and the stem-wilting bug Catorhintha schaffneri (Coreidae), have been released in South Africa thus far. Post-release evaluations have indicated that P. guerini will not reduce P. aculeata densities to acceptable levels alone, while C. schaffneri was released very recently, so it is too soon to determine how effective that agent will be. Even if C. schaffneri is extremely damaging, it is likely that further agents will be required to reduce the densities of P. aculeata to acceptable levels within a reasonable time-scale. Additional agents should target the woody stems of P. aculeata which are not impacted by the damage of either of the released agents. Pereskiophaga brasiliensis Anderson (Curculionidae) is a promising potential candidate agent that feeds on the thick woody stems of the plant in the larval stage. Climatic matching, genetic matching and field based host specificity observations all indicated that P. brasiliensis was a promising candidate. In this study, the impact of P. brasiliensis to the target weed, P. aculeata, was quantified under quarantine conditions to determine whether it was sufficiently damaging to warrant release. This was followed by host specificity testing to determine whether P. brasiliensis was suitably host specific for release in South Africa. Impact studies indicated that P. brasiliensis was damaging to P. aculeata at insect densities that would be expected in the field. Pereskiophaga brasiliensis reduced the number of leaves of P. aculeata to a greater extent than it reduced shoot lengths, but both plant parameters were significantly reduced due to the feeding damage from the insect. This suggests that the damage from P. brasiliensis may be compatible with that of C. schaffneri which reduces shoot length to a greater degree than the number of leaves. Pereskiophaga brasiliensis is therefore sufficiently damaging to warrant release, and although interaction studies with the other agents would be required, it is expected that it should complement other existing agents. Although P. brasiliensis is sufficiently damaging, at present the host specificity data indicates that it is not suitably specific for release in South Africa because oviposition and larval development to the adult stage was recorded on both indigenous and alien plant species within the families Cactaceae and Basellaceae. This non-target feeding was recorded during no-choice tests, which are very conservative, but significant non-target damage and development to the adult stage was recorded on an indigenous plant from a different family to the target weed. Further host specificity testing, including paired and multiple choice tests, are required to confirm the broad host range of P. brasiliensis. Other biological control agents that damage the woody stems of P. aculeata should be considered. The stem-borer, Acanthodoxus machacalis (Cerambycidae) is considered the most promising of the other candidate agents as it can be sourced from a climatically matched region where genetically suitable P. aculeata plants are found, it is sufficiently damaging to the woody stems of P. aculeata and there is no evidence that the species has a broad host range. Acanthodoxus machacalis should be sourced from Rio de Janeiro, Brazil, and imported into quarantine in South Africa for host specificity testing.
- Full Text:
- Date Issued: 2018
- Authors: Mdodana, Lumka Anita
- Date: 2018
- Subjects: Curculionidae -- South Africa , Cactus -- South Africa , Biological pest control agents , Alien plants-- South Africa , Pereskiophaga brasiliensis Anderson (Curculionidae) , Pereskia aculeata Miller (Cactaceae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62350 , vital:28157
- Description: Pereskia aculeata Miller (Cactaceae) is a damaging invasive alien plant in South Africa that has negative impacts to indigenous biodiversity and ecosystem functioning. Mechanical and chemical control are not effective against P. aculeata so biological control is considered the only viable option. Two biological control agents, the leaf-feeding beetle Phenrica guerini Bechyne (Chrysomelidae) and the stem-wilting bug Catorhintha schaffneri (Coreidae), have been released in South Africa thus far. Post-release evaluations have indicated that P. guerini will not reduce P. aculeata densities to acceptable levels alone, while C. schaffneri was released very recently, so it is too soon to determine how effective that agent will be. Even if C. schaffneri is extremely damaging, it is likely that further agents will be required to reduce the densities of P. aculeata to acceptable levels within a reasonable time-scale. Additional agents should target the woody stems of P. aculeata which are not impacted by the damage of either of the released agents. Pereskiophaga brasiliensis Anderson (Curculionidae) is a promising potential candidate agent that feeds on the thick woody stems of the plant in the larval stage. Climatic matching, genetic matching and field based host specificity observations all indicated that P. brasiliensis was a promising candidate. In this study, the impact of P. brasiliensis to the target weed, P. aculeata, was quantified under quarantine conditions to determine whether it was sufficiently damaging to warrant release. This was followed by host specificity testing to determine whether P. brasiliensis was suitably host specific for release in South Africa. Impact studies indicated that P. brasiliensis was damaging to P. aculeata at insect densities that would be expected in the field. Pereskiophaga brasiliensis reduced the number of leaves of P. aculeata to a greater extent than it reduced shoot lengths, but both plant parameters were significantly reduced due to the feeding damage from the insect. This suggests that the damage from P. brasiliensis may be compatible with that of C. schaffneri which reduces shoot length to a greater degree than the number of leaves. Pereskiophaga brasiliensis is therefore sufficiently damaging to warrant release, and although interaction studies with the other agents would be required, it is expected that it should complement other existing agents. Although P. brasiliensis is sufficiently damaging, at present the host specificity data indicates that it is not suitably specific for release in South Africa because oviposition and larval development to the adult stage was recorded on both indigenous and alien plant species within the families Cactaceae and Basellaceae. This non-target feeding was recorded during no-choice tests, which are very conservative, but significant non-target damage and development to the adult stage was recorded on an indigenous plant from a different family to the target weed. Further host specificity testing, including paired and multiple choice tests, are required to confirm the broad host range of P. brasiliensis. Other biological control agents that damage the woody stems of P. aculeata should be considered. The stem-borer, Acanthodoxus machacalis (Cerambycidae) is considered the most promising of the other candidate agents as it can be sourced from a climatically matched region where genetically suitable P. aculeata plants are found, it is sufficiently damaging to the woody stems of P. aculeata and there is no evidence that the species has a broad host range. Acanthodoxus machacalis should be sourced from Rio de Janeiro, Brazil, and imported into quarantine in South Africa for host specificity testing.
- Full Text:
- Date Issued: 2018
Development and assessment of a smart thermosetting intranasal hydrogel for lamotrigine
- Authors: Melamane, Siyabonga
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62975 , vital:28349
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Melamane, Siyabonga
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62975 , vital:28349
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Macroinvertebrate and diatom assemblage responses to pollution, with emphasis on salinity, in the Kat River, Eastern Cape South Africa
- Authors: Mgaba, Ntombekhaya
- Date: 2018
- Subjects: Water -- Pollution -- South Africa -- Kat River , Stream salinity -- South Africa -- Kat River , Sewage disposal plants -- South Africa , Environmental monitoring -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , South African Scoring System version 5 (SASS5) , Macroinvertebrate Response Assessment Index (MIRAI)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63279 , vital:28389
- Description: Salinity has been implicated as one of the major contributors to deteriorating water quality of freshwater ecosystems around the globe. In South Africa, anthropogenic activities such as mining, agriculture, industry and wastewater treatment works (WWTWs) are the major sources of increasing salinity levels of freshwater resources. The main focus of this study was to assess the impact of salinity on water quality of the Kat River using macroinvertebrates and diatoms as bioindicators. Biomonitoring using macroinvertebrates and diatom communities and concurrent sampling of water physicochemical variables were conducted bi-monthly from December 2015 to November 2016.This period covered summer and winter, and the study was conducted at five selected sites (Sites 1, 2, 3, 4 and 5) along the length of the Kat River. For macroinvertebrates biomonitoring, the South African Scoring System version 5 (SASS5) and Macroinvertebrate Response Assessment Index (MIRAI) were applied to collect and analyse data, while the Taylor et al (2006) protocol for collecting and analysing diatom assemblages was modified and used for diatom collection and analysis. Water physicochemical variables, including hydrogen ion concentration (pH), electrical conductivity (EC), dissolved oxygen (DO), temperature, turbidity and stream flow were determined in situ using appropriate multiprobe meter and/or techniques. Nutrients (NO3-N, NO2-N, NH4-N and PO4-P) were analysed in the laboratory using appropriate analytical methods. All data were subjected to appropriate statistical analyses and statistical decisions were made at an alpha value of 0.05. Particularly, multivariate analyses of both macroinvertebrates and diatoms assemblages were conducted using canonical correspondence analysis and Bray-Curtis similarity analysis, while indicator species analysis was used to determine which species is/are more significant with respect to biomonitoring in the Kat River. Biotic diversity indices were also measured and used to discriminate between least and most impacted sites. The Kat River water quality was found to have experienced a varying degree of modification compared to Generic Resources Water Quality Objectives limits. Change in DO, stream flow, EC, nutrients and turbidity exerted the greatest influenced on the macroinvertebrates assemblage structure, with organisms at Sites 4 and 5 (downstream sites) showing more significant negative impact compared to organisms at Sites 1, 2 and 3 (upstream sites). Analysis of the diatom biomonitoring showed more negative impact at Sites 2, 4 and 5 compared to Sites 1 and 3. Fort Beaufort Wastewater Treatment Works and small-scale farming activities, as well as leaking of pipes carrying sewage, were found to be the likely major sources of anthropogenic activities responsible for the observed increased salinity and other pollutants in the Kat River. Overall, this study found macroinvertebrates (identified up to the family level) as good for biomonitoring to assess or predict water quality of the Kat River, while diatoms were found to be most suitable for biomonitoring to assess salinity in the Kat River.
- Full Text:
- Date Issued: 2018
- Authors: Mgaba, Ntombekhaya
- Date: 2018
- Subjects: Water -- Pollution -- South Africa -- Kat River , Stream salinity -- South Africa -- Kat River , Sewage disposal plants -- South Africa , Environmental monitoring -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , South African Scoring System version 5 (SASS5) , Macroinvertebrate Response Assessment Index (MIRAI)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63279 , vital:28389
- Description: Salinity has been implicated as one of the major contributors to deteriorating water quality of freshwater ecosystems around the globe. In South Africa, anthropogenic activities such as mining, agriculture, industry and wastewater treatment works (WWTWs) are the major sources of increasing salinity levels of freshwater resources. The main focus of this study was to assess the impact of salinity on water quality of the Kat River using macroinvertebrates and diatoms as bioindicators. Biomonitoring using macroinvertebrates and diatom communities and concurrent sampling of water physicochemical variables were conducted bi-monthly from December 2015 to November 2016.This period covered summer and winter, and the study was conducted at five selected sites (Sites 1, 2, 3, 4 and 5) along the length of the Kat River. For macroinvertebrates biomonitoring, the South African Scoring System version 5 (SASS5) and Macroinvertebrate Response Assessment Index (MIRAI) were applied to collect and analyse data, while the Taylor et al (2006) protocol for collecting and analysing diatom assemblages was modified and used for diatom collection and analysis. Water physicochemical variables, including hydrogen ion concentration (pH), electrical conductivity (EC), dissolved oxygen (DO), temperature, turbidity and stream flow were determined in situ using appropriate multiprobe meter and/or techniques. Nutrients (NO3-N, NO2-N, NH4-N and PO4-P) were analysed in the laboratory using appropriate analytical methods. All data were subjected to appropriate statistical analyses and statistical decisions were made at an alpha value of 0.05. Particularly, multivariate analyses of both macroinvertebrates and diatoms assemblages were conducted using canonical correspondence analysis and Bray-Curtis similarity analysis, while indicator species analysis was used to determine which species is/are more significant with respect to biomonitoring in the Kat River. Biotic diversity indices were also measured and used to discriminate between least and most impacted sites. The Kat River water quality was found to have experienced a varying degree of modification compared to Generic Resources Water Quality Objectives limits. Change in DO, stream flow, EC, nutrients and turbidity exerted the greatest influenced on the macroinvertebrates assemblage structure, with organisms at Sites 4 and 5 (downstream sites) showing more significant negative impact compared to organisms at Sites 1, 2 and 3 (upstream sites). Analysis of the diatom biomonitoring showed more negative impact at Sites 2, 4 and 5 compared to Sites 1 and 3. Fort Beaufort Wastewater Treatment Works and small-scale farming activities, as well as leaking of pipes carrying sewage, were found to be the likely major sources of anthropogenic activities responsible for the observed increased salinity and other pollutants in the Kat River. Overall, this study found macroinvertebrates (identified up to the family level) as good for biomonitoring to assess or predict water quality of the Kat River, while diatoms were found to be most suitable for biomonitoring to assess salinity in the Kat River.
- Full Text:
- Date Issued: 2018
The potential significance of refugia in safeguarding Non-Timber Forest products under Harvesting
- Authors: Mjoli, Nwabisa
- Date: 2018
- Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60596 , vital:27801
- Description: Many rural households living in and adjacent to forests in South Africa harvest a variety of NonTimber Forest Products (NTFPs) such as wild fruits, fibre, fuelwood, seeds, medicine and bush meat for domestic use, sale and maintaining cultural values. To promote the continued availability of these NTFPs it is important that NTFPs are well maintained and that harvest offtake is sustainable, because if it is not, then the important livelihood function that they fulfil will be jeopardized over time. The role of refugia in conserving pockets of threatened species from overharvesting has rarely been considered. Building on Shackleton et al. (2015), six applications of the concept are considered: size refugia, spatial refugia, cultural/spiritual refugia and physical/habitat refugia. I examined the prevalence and type of refugia for NTFPs at three coastal sites in the Eastern Cape province of South Africa. This was done via several community focus group discussions at each site. Here I report on the role of refugia in offering some safeguard to NTFPs by assessing harvested and non-harvested sites of refugia as well as individual plant species by measuring population density, harvest damage and size class profile. Respondents from the focus group discussions perceived a general decline in the abundance of common, widely used species over the past five decades. Decreasing rainfall and distant farming activities was reported consistently by the majority of the respondents. The most common form of refugia was spatial refugia, followed by cultural/spiritual refugia and physical/habitat refugia. Only six species were identified to be in refugia, namely Cyperus congestus, Cyperus textillis, Millettia grandis, Olea europaea subsp. africana, Phoenix reclinata, and Ptaeroxylon obliquum. Population inventories revealed that regeneration and population densities of some NTFP species in the non-refuge site were adversely affected by harvesting. Populations in refuge sites generally had the largest size classes indicating a regeneration potential but likely to impact regeneration over time if pressures are maintained. Therefore, if refuge sites keep larger individuals, NTFP populations can be maintained. Few studies have critically analyzed the concept of refugia in relation to how NTFPs can be safeguarded and the practical implication of the refuge concept needs to be considered in conservation and strategies and population models.
- Full Text:
- Date Issued: 2018
- Authors: Mjoli, Nwabisa
- Date: 2018
- Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60596 , vital:27801
- Description: Many rural households living in and adjacent to forests in South Africa harvest a variety of NonTimber Forest Products (NTFPs) such as wild fruits, fibre, fuelwood, seeds, medicine and bush meat for domestic use, sale and maintaining cultural values. To promote the continued availability of these NTFPs it is important that NTFPs are well maintained and that harvest offtake is sustainable, because if it is not, then the important livelihood function that they fulfil will be jeopardized over time. The role of refugia in conserving pockets of threatened species from overharvesting has rarely been considered. Building on Shackleton et al. (2015), six applications of the concept are considered: size refugia, spatial refugia, cultural/spiritual refugia and physical/habitat refugia. I examined the prevalence and type of refugia for NTFPs at three coastal sites in the Eastern Cape province of South Africa. This was done via several community focus group discussions at each site. Here I report on the role of refugia in offering some safeguard to NTFPs by assessing harvested and non-harvested sites of refugia as well as individual plant species by measuring population density, harvest damage and size class profile. Respondents from the focus group discussions perceived a general decline in the abundance of common, widely used species over the past five decades. Decreasing rainfall and distant farming activities was reported consistently by the majority of the respondents. The most common form of refugia was spatial refugia, followed by cultural/spiritual refugia and physical/habitat refugia. Only six species were identified to be in refugia, namely Cyperus congestus, Cyperus textillis, Millettia grandis, Olea europaea subsp. africana, Phoenix reclinata, and Ptaeroxylon obliquum. Population inventories revealed that regeneration and population densities of some NTFP species in the non-refuge site were adversely affected by harvesting. Populations in refuge sites generally had the largest size classes indicating a regeneration potential but likely to impact regeneration over time if pressures are maintained. Therefore, if refuge sites keep larger individuals, NTFP populations can be maintained. Few studies have critically analyzed the concept of refugia in relation to how NTFPs can be safeguarded and the practical implication of the refuge concept needs to be considered in conservation and strategies and population models.
- Full Text:
- Date Issued: 2018
Sulphur isotope study of pyrite from the Twangiza-Namoya Gold Belt, (South Kivu, DRC): a proxy of gold provenance
- Moloto, Thapelo Refiloe Patience
- Authors: Moloto, Thapelo Refiloe Patience
- Date: 2018
- Subjects: Isotope geology -- Congo (Democratic Republic) , Pyrites -- Congo (Democratic Republic) , Gold mines and mining -- Congo (Democratic Republic) , Sulfur -- Isotopes -- Congo (Democratic Republic) , Hydrothermal deposits -- Congo (Democratic Republic) , Twangiza-Namoya Gold Belt, (South Kivu, DRC)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60552 , vital:27793
- Description: Gold in the highly prospective Twangiza-Namoya Gold Belt (TNGB) in the eastern Democratic Republic of Congo (DRC), with its four main deposits at Twangiza, Kamituga, Lugushwa and Namoya, appears to be correlated with the presence of sulphide minerals. Sulphur isotopic compositions of pyrite in the metasedimentary host rocks and in hydrothermal veins are used to identify the possible primary sources of hydrothermal sulphur and, by proxy, hydrothermal gold. The sulphur isotope signatures of the pyrites from the TNGB deposits show an overall range from -18.4%o to +22.6%o. S34 values in host rock pyrite are: -2.2%o to +3.0%o (Twangiza deposit), -4.2%o to -0.6% (Kamituga deposit), -18.4% to -12.7% (Lugushwa deposit), and +12.4% to +22.6% (Namoya deposit). The sulphur isotopic signature of vein pyrite is -5.2% to +3.0% (Twangiza deposit), -9.1% to -7.4% (Kamituga deposit), -0.3% to +3.2% (Lugushwa deposit) and +1.3% to +20.4% (Namoya deposit). The isotopic data indicate a primary sedimentary to evaporitic source of sulphur in the host rock pyrite. Pyrite from metadiorites shows magmatic S isotope compositions. Native gold was found in both sedimentary host rock and vein samples. This indicates that native gold was present in the primary metasedimentary sequence of the TNGB. Some vein pyrites in the TNGB have isotopic signatures that are similar to that of the host rock pyrite. These veins have formed from fluids extracted from the hosting metasedimentary sequence. Conversely, other vein pyrite shows different S34S values compared to the host rock pyrite, suggesting a fluid source that is different from the sedimentary source. Possibly, particularly in the Lugushwa deposit, an igneous source may have released sulphur and possibly gold bearing fluids in addition to those extracted from the sedimentary sequences in the TNGB. However, there is abundant evidence for sulphur and gold mobilised in the sedimentary host rocks and precipitated in the hydrothermal system of the TNGB.
- Full Text:
- Date Issued: 2018
- Authors: Moloto, Thapelo Refiloe Patience
- Date: 2018
- Subjects: Isotope geology -- Congo (Democratic Republic) , Pyrites -- Congo (Democratic Republic) , Gold mines and mining -- Congo (Democratic Republic) , Sulfur -- Isotopes -- Congo (Democratic Republic) , Hydrothermal deposits -- Congo (Democratic Republic) , Twangiza-Namoya Gold Belt, (South Kivu, DRC)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60552 , vital:27793
- Description: Gold in the highly prospective Twangiza-Namoya Gold Belt (TNGB) in the eastern Democratic Republic of Congo (DRC), with its four main deposits at Twangiza, Kamituga, Lugushwa and Namoya, appears to be correlated with the presence of sulphide minerals. Sulphur isotopic compositions of pyrite in the metasedimentary host rocks and in hydrothermal veins are used to identify the possible primary sources of hydrothermal sulphur and, by proxy, hydrothermal gold. The sulphur isotope signatures of the pyrites from the TNGB deposits show an overall range from -18.4%o to +22.6%o. S34 values in host rock pyrite are: -2.2%o to +3.0%o (Twangiza deposit), -4.2%o to -0.6% (Kamituga deposit), -18.4% to -12.7% (Lugushwa deposit), and +12.4% to +22.6% (Namoya deposit). The sulphur isotopic signature of vein pyrite is -5.2% to +3.0% (Twangiza deposit), -9.1% to -7.4% (Kamituga deposit), -0.3% to +3.2% (Lugushwa deposit) and +1.3% to +20.4% (Namoya deposit). The isotopic data indicate a primary sedimentary to evaporitic source of sulphur in the host rock pyrite. Pyrite from metadiorites shows magmatic S isotope compositions. Native gold was found in both sedimentary host rock and vein samples. This indicates that native gold was present in the primary metasedimentary sequence of the TNGB. Some vein pyrites in the TNGB have isotopic signatures that are similar to that of the host rock pyrite. These veins have formed from fluids extracted from the hosting metasedimentary sequence. Conversely, other vein pyrite shows different S34S values compared to the host rock pyrite, suggesting a fluid source that is different from the sedimentary source. Possibly, particularly in the Lugushwa deposit, an igneous source may have released sulphur and possibly gold bearing fluids in addition to those extracted from the sedimentary sequences in the TNGB. However, there is abundant evidence for sulphur and gold mobilised in the sedimentary host rocks and precipitated in the hydrothermal system of the TNGB.
- Full Text:
- Date Issued: 2018
A seismic characterization of the crustal structure underlying the offshore Natal valley within the south-west Indian Ocean
- Authors: Moorcroft, David
- Date: 2018
- Subjects: Seismology , Seismology -- Kwa Zulu Natal -- Research Coasts -- Kwa Zulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22387 , vital:29965
- Description: The Natal Valley is a ~1000 km long, elongated depression in the seafloor, located within the south-west Indian Ocean, between the coastline of south-east Africa and the offshore aseismic Mozambique Ridge. Knowledge of its present-day crustal structure is important to reconstruct the Gondwana supercontinent break-up history and the concurrent opening of the Indian Ocean, which started during the Jurassic, some ~180 – 150 million years ago. Major geological events relating to this supercontinent break-up including continental rifting, magmatism, the emplacement of extensive oceanic flood basalt as submarine plateaus, vertical processes associated with tectonic uplift, flexural subsidence of the margin and relative global sea-level change are recorded within the crust underlying the south-west Indian Ocean. Although these events have been well modelled, fundamental questions remain regarding the nature and tectonic structure of the crust. Today, the Natal Valley region represents a frontier for geophysical exploration. Early attempts at imaging the crust beneath the seafloor within the south-west Indian Ocean made use of now primitive seismic reflection data acquisition and processing techniques available to them at the time (1960’s - 1970’s). Considering the advancements made in marine seismic reflection imaging, these vintage datasets lacked the horizontal and vertical resolution necessary to most accurately account for and describe features of the upper crust underlying the northern Natal Valley. This study is based on the acquisition, processing and preliminary interpretation of a newly acquired, regional seismic reflection profile, Profile Mz5-007, acquired across the northernmost region of the Natal Valley during the PAMELA-Moz5 cruise in 2016. The methods of marine seismic reflection data acquisition, processing and interpretation are described. The seismic reflection data presented in this dissertation provides a regional-scaled appraisal of the upper crust underlying the northern Natal Valley for the first time. The imagery allows a comprehensive description of crustal structures and features from the very northern Natal Valley, close to the Mozambique coastline, southwards into the southern Natal Valley offshore of Durban. The findings presented here support the notion that the crust underlying the northern Natal Valley experienced roughly N-S orientated trans-tensional stresses in relation to the breakup of West Gondwana. At least two major phases of volcanism are imaged within the seismic stratigraphy. The lower-most event underlies the Limpopo Fan in the northernmost regions of the Natal Valley at a depth of 2 seconds TWT and is interpreted as a seismic expression of the upper surface of the Lower – Middle Jurassic Karoo LIP. The progressive disappearance of this horizon towards the south coincides with the emergence of a second, overlying, as yet unreported volcanic horizon, which extends southwards throughout the Natal Valley. On the basis of its regional distribution, spatial relationship with the underlying event boundary and its deformation history, this volcanic horizon is interpreted to represent a series of basaltic lava outpourings during the Lower Cretaceous, initiated in response to trans-tensional crustal deformation associated with the breakup of West Gondwana. In addition to these two major phases of flood basalt outpouring, a number of localized volcanic flows are imaged throughout the stratigraphy, most notably over the Central Terrace. In addition, at least four major unconformities are identified, all of which are well developed within the Limpopo Fan. One of these is interpreted to represent the well-developed Mid-Cretaceous hiatus in sedimentation, providing a relative seismo-stratigraphic constraint to overlying and underlying seismic units. A review of the structural elements of the crust reveals how the northern Natal Valley is partitioned into two sub-basins separated by a prominent basement high, the Central Terrace, imaged across the central portions of Profile Mz5-007. To the north of the Central Terrace, structural deformation appears largely extensional, characterized by a large (~37 km wide) asymmetrical depression directly to the north of the Central Terrace and only minor structural faulting. To the south of the Central Terrace, trans-tensional stresses associated with withdrawal of the Falkland Malvinas Plateau have deformed the upper crust into a series of apparently southwards tilted crustal blocks, producing a series of deep (3.5 s TWT) half graben-like structures, within which syn-rift fill has an apparent dip towards the south. There is evidence to suggest ongoing reactivation of these fault structures. This zone of deformation is shown to bear resemblances to the faulting mapped onshore of the Kwa-Zulu Natal coastline, providing reason to consider the two regions as a continuous zone of deformation associated with the withdrawal of the Falkland-Malvinas Plateau during the breakup of West Gondwana. Furthermore, a number of post-sedimentary intrusive features are imaged, the largest of which is the Naude Ridge; a large pinnacle-like feature which has penetrated the upper crust towards the southern limit of the profile. This feature corresponds to an abrupt change in seafloor depth and upper crustal structure, suggesting that this feature may mark the transition between subsided continental crust interpreted to underlie the northern Natal Valley to the north and oceanic crust known to underlie the southern Natal Valley to the south.
- Full Text:
- Date Issued: 2018
- Authors: Moorcroft, David
- Date: 2018
- Subjects: Seismology , Seismology -- Kwa Zulu Natal -- Research Coasts -- Kwa Zulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22387 , vital:29965
- Description: The Natal Valley is a ~1000 km long, elongated depression in the seafloor, located within the south-west Indian Ocean, between the coastline of south-east Africa and the offshore aseismic Mozambique Ridge. Knowledge of its present-day crustal structure is important to reconstruct the Gondwana supercontinent break-up history and the concurrent opening of the Indian Ocean, which started during the Jurassic, some ~180 – 150 million years ago. Major geological events relating to this supercontinent break-up including continental rifting, magmatism, the emplacement of extensive oceanic flood basalt as submarine plateaus, vertical processes associated with tectonic uplift, flexural subsidence of the margin and relative global sea-level change are recorded within the crust underlying the south-west Indian Ocean. Although these events have been well modelled, fundamental questions remain regarding the nature and tectonic structure of the crust. Today, the Natal Valley region represents a frontier for geophysical exploration. Early attempts at imaging the crust beneath the seafloor within the south-west Indian Ocean made use of now primitive seismic reflection data acquisition and processing techniques available to them at the time (1960’s - 1970’s). Considering the advancements made in marine seismic reflection imaging, these vintage datasets lacked the horizontal and vertical resolution necessary to most accurately account for and describe features of the upper crust underlying the northern Natal Valley. This study is based on the acquisition, processing and preliminary interpretation of a newly acquired, regional seismic reflection profile, Profile Mz5-007, acquired across the northernmost region of the Natal Valley during the PAMELA-Moz5 cruise in 2016. The methods of marine seismic reflection data acquisition, processing and interpretation are described. The seismic reflection data presented in this dissertation provides a regional-scaled appraisal of the upper crust underlying the northern Natal Valley for the first time. The imagery allows a comprehensive description of crustal structures and features from the very northern Natal Valley, close to the Mozambique coastline, southwards into the southern Natal Valley offshore of Durban. The findings presented here support the notion that the crust underlying the northern Natal Valley experienced roughly N-S orientated trans-tensional stresses in relation to the breakup of West Gondwana. At least two major phases of volcanism are imaged within the seismic stratigraphy. The lower-most event underlies the Limpopo Fan in the northernmost regions of the Natal Valley at a depth of 2 seconds TWT and is interpreted as a seismic expression of the upper surface of the Lower – Middle Jurassic Karoo LIP. The progressive disappearance of this horizon towards the south coincides with the emergence of a second, overlying, as yet unreported volcanic horizon, which extends southwards throughout the Natal Valley. On the basis of its regional distribution, spatial relationship with the underlying event boundary and its deformation history, this volcanic horizon is interpreted to represent a series of basaltic lava outpourings during the Lower Cretaceous, initiated in response to trans-tensional crustal deformation associated with the breakup of West Gondwana. In addition to these two major phases of flood basalt outpouring, a number of localized volcanic flows are imaged throughout the stratigraphy, most notably over the Central Terrace. In addition, at least four major unconformities are identified, all of which are well developed within the Limpopo Fan. One of these is interpreted to represent the well-developed Mid-Cretaceous hiatus in sedimentation, providing a relative seismo-stratigraphic constraint to overlying and underlying seismic units. A review of the structural elements of the crust reveals how the northern Natal Valley is partitioned into two sub-basins separated by a prominent basement high, the Central Terrace, imaged across the central portions of Profile Mz5-007. To the north of the Central Terrace, structural deformation appears largely extensional, characterized by a large (~37 km wide) asymmetrical depression directly to the north of the Central Terrace and only minor structural faulting. To the south of the Central Terrace, trans-tensional stresses associated with withdrawal of the Falkland Malvinas Plateau have deformed the upper crust into a series of apparently southwards tilted crustal blocks, producing a series of deep (3.5 s TWT) half graben-like structures, within which syn-rift fill has an apparent dip towards the south. There is evidence to suggest ongoing reactivation of these fault structures. This zone of deformation is shown to bear resemblances to the faulting mapped onshore of the Kwa-Zulu Natal coastline, providing reason to consider the two regions as a continuous zone of deformation associated with the withdrawal of the Falkland-Malvinas Plateau during the breakup of West Gondwana. Furthermore, a number of post-sedimentary intrusive features are imaged, the largest of which is the Naude Ridge; a large pinnacle-like feature which has penetrated the upper crust towards the southern limit of the profile. This feature corresponds to an abrupt change in seafloor depth and upper crustal structure, suggesting that this feature may mark the transition between subsided continental crust interpreted to underlie the northern Natal Valley to the north and oceanic crust known to underlie the southern Natal Valley to the south.
- Full Text:
- Date Issued: 2018
Designing and prototyping WebRTC and IMS integration using open source tools
- Authors: Motsumi, Tebagano Valerie
- Date: 2018
- Subjects: Internet Protocol multimedia subsystem , Session Initiation Protocol (Computer network protocol) , Computer software -- Development , Web Real-time Communications (WebRTC)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63245 , vital:28386
- Description: WebRTC, or Web Real-time Communications, is a collection of web standards that detail the mechanisms, architectures and protocols that work together to deliver real-time multimedia services to the web browser. It represents a significant shift from the historical approach of using browser plugins, which over time, have proven cumbersome and problematic. Furthermore, it adopts various Internet standards in areas such as identity management, peer-to-peer connectivity, data exchange and media encoding, to provide a system that is truly open and interoperable. Given that WebRTC enables the delivery of multimedia content to any Internet Protocol (IP)-enabled device capable of hosting a web browser, this technology could potentially be used and deployed over millions of smartphones, tablets and personal computers worldwide. This service and device convergence remains an important goal of telecommunication network operators who seek to enable it through a converged network that is based on the IP Multimedia Subsystem (IMS). IMS is an IP-based subsystem that sits at the core of a modern telecommunication network and acts as the main routing substrate for media services and applications such as those that WebRTC realises. The combination of WebRTC and IMS represents an attractive coupling, and as such, a protracted investigation could help to answer important questions around the technical challenges that are involved in their integration, and the merits of various design alternatives that present themselves. This thesis is the result of such an investigation and culminates in the presentation of a detailed architectural model that is validated with a prototypical implementation in an open source testbed. The model is built on six requirements which emerge from an analysis of the literature, including previous interventions in IMS networks and a key technical report on design alternatives. Furthermore, this thesis argues that the client architecture requires support for web-oriented signalling, identity and call handling techniques leading to a potential for IMS networks to natively support these techniques as operator networks continue to grow and develop. The proposed model advocates the use of SIP over WebSockets for signalling and DTLS-SRTP for media to enable one-to-one communication and can be extended through additional functions resulting in a modular architecture. The model was implemented using open source tools which were assembled to create an experimental network testbed, and tests were conducted demonstrating successful cross domain communications under various conditions. The thesis has a strong focus on enabling ordinary software developers to assemble a prototypical network such as the one that was assembled and aims to enable experimentation in application use cases for integrated environments.
- Full Text:
- Date Issued: 2018
- Authors: Motsumi, Tebagano Valerie
- Date: 2018
- Subjects: Internet Protocol multimedia subsystem , Session Initiation Protocol (Computer network protocol) , Computer software -- Development , Web Real-time Communications (WebRTC)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63245 , vital:28386
- Description: WebRTC, or Web Real-time Communications, is a collection of web standards that detail the mechanisms, architectures and protocols that work together to deliver real-time multimedia services to the web browser. It represents a significant shift from the historical approach of using browser plugins, which over time, have proven cumbersome and problematic. Furthermore, it adopts various Internet standards in areas such as identity management, peer-to-peer connectivity, data exchange and media encoding, to provide a system that is truly open and interoperable. Given that WebRTC enables the delivery of multimedia content to any Internet Protocol (IP)-enabled device capable of hosting a web browser, this technology could potentially be used and deployed over millions of smartphones, tablets and personal computers worldwide. This service and device convergence remains an important goal of telecommunication network operators who seek to enable it through a converged network that is based on the IP Multimedia Subsystem (IMS). IMS is an IP-based subsystem that sits at the core of a modern telecommunication network and acts as the main routing substrate for media services and applications such as those that WebRTC realises. The combination of WebRTC and IMS represents an attractive coupling, and as such, a protracted investigation could help to answer important questions around the technical challenges that are involved in their integration, and the merits of various design alternatives that present themselves. This thesis is the result of such an investigation and culminates in the presentation of a detailed architectural model that is validated with a prototypical implementation in an open source testbed. The model is built on six requirements which emerge from an analysis of the literature, including previous interventions in IMS networks and a key technical report on design alternatives. Furthermore, this thesis argues that the client architecture requires support for web-oriented signalling, identity and call handling techniques leading to a potential for IMS networks to natively support these techniques as operator networks continue to grow and develop. The proposed model advocates the use of SIP over WebSockets for signalling and DTLS-SRTP for media to enable one-to-one communication and can be extended through additional functions resulting in a modular architecture. The model was implemented using open source tools which were assembled to create an experimental network testbed, and tests were conducted demonstrating successful cross domain communications under various conditions. The thesis has a strong focus on enabling ordinary software developers to assemble a prototypical network such as the one that was assembled and aims to enable experimentation in application use cases for integrated environments.
- Full Text:
- Date Issued: 2018
The spatial ecology of Albula glossodonta in the St. Joseph Atoll, Seychelles
- Authors: Moxham, Emily Jeanne
- Date: 2018
- Subjects: Bonefish -- Seychelles -- Amirante Islands , Albula -- Seychelles -- Amirante Islands , Bonefish fisheries -- Seychelles -- Amirante Islands , Small-scale fisheries -- Seychelles -- Amirante Islands -- Economic conditions , Underwater acoustic telemetry , Bonefish -- Behavior -- Seychelles -- Amirante Islands , Bonefish -- Home range -- Seychelles -- Amirante Islands , Bonefish -- Conservation -- Seychelles -- Amirante Islands , Predation (Biology) -- Seychelles -- Amirante Islands , Bonefishing
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57863 , vital:26997
- Description: Bonefish (Albula spp.) support valuable recreational and artisanal fisheries worldwide. Declining stocks have been reported at multiple localities, potentially jeopardising numerous multimillion-dollar industries. In particular, tourism generated through bonefish fly fishing contributes considerably to the economies of many isolated tropical islands and atolls. However, despite their economic value, little is known about bonefish in the Indian Ocean. This study aimed to contribute to the understanding of bonefish ecology in the Indian Ocean by (1) reviewing the bonefish literature to identify knowledge gaps; (2) evaluating the postrelease survival of acoustically tagged bonefish and; (3) quantifying the spatial and temporal movements of bonefish at a near-pristine and predator rich atoll in the Seychelles. A review of published literature on bonefish indicated that despite considerable biological and ecological research in the Pacific and Atlantic oceans, virtually no research has been conducted in the Indian Ocean. To help address this research gap, an acoustic telemetry study was initiated at the remote St. Joseph Atoll, within an existing array of 88 automated datalogging acoustic receivers. Thirty Albula glossodonta were surgically implanted with Vemco V13 acoustic transmitters in May 2015 and tracked for a period of one year. Only 10% of the tagged bonefish were detected for more than two weeks. A comparison of the final 100 hours of movement data from fish that were detected for less than two weeks to fish detected for longer periods revealed distinct differences. These included differences in area use patterns and significant differences in the average daily distance moved, speed of movement and residency index. This suggested that mortality in the form of post-release predation was high (90%) with tagged fish detected for less than two weeks being preyed upon by sharks. The three surviving bonefish were tracked for 210 to 367 days. These individuals remained in the atoll and showed high use of the marginal habitats between the shallow sand flats and the deeper lagoon. Water temperature, diel cycle and tide were significant predictors of bonefish presence in the lagoon. The high post-release predation of bonefish has implications for the management of this and other Albula species. Despite these fisheries being catch-and-release, bonefish fishing may be unsustainable due to the high post-release mortality, particularly in areas that are rich in predators. Therefore, protected areas or limitations on fishing effort need to be considered.
- Full Text:
- Date Issued: 2018
- Authors: Moxham, Emily Jeanne
- Date: 2018
- Subjects: Bonefish -- Seychelles -- Amirante Islands , Albula -- Seychelles -- Amirante Islands , Bonefish fisheries -- Seychelles -- Amirante Islands , Small-scale fisheries -- Seychelles -- Amirante Islands -- Economic conditions , Underwater acoustic telemetry , Bonefish -- Behavior -- Seychelles -- Amirante Islands , Bonefish -- Home range -- Seychelles -- Amirante Islands , Bonefish -- Conservation -- Seychelles -- Amirante Islands , Predation (Biology) -- Seychelles -- Amirante Islands , Bonefishing
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57863 , vital:26997
- Description: Bonefish (Albula spp.) support valuable recreational and artisanal fisheries worldwide. Declining stocks have been reported at multiple localities, potentially jeopardising numerous multimillion-dollar industries. In particular, tourism generated through bonefish fly fishing contributes considerably to the economies of many isolated tropical islands and atolls. However, despite their economic value, little is known about bonefish in the Indian Ocean. This study aimed to contribute to the understanding of bonefish ecology in the Indian Ocean by (1) reviewing the bonefish literature to identify knowledge gaps; (2) evaluating the postrelease survival of acoustically tagged bonefish and; (3) quantifying the spatial and temporal movements of bonefish at a near-pristine and predator rich atoll in the Seychelles. A review of published literature on bonefish indicated that despite considerable biological and ecological research in the Pacific and Atlantic oceans, virtually no research has been conducted in the Indian Ocean. To help address this research gap, an acoustic telemetry study was initiated at the remote St. Joseph Atoll, within an existing array of 88 automated datalogging acoustic receivers. Thirty Albula glossodonta were surgically implanted with Vemco V13 acoustic transmitters in May 2015 and tracked for a period of one year. Only 10% of the tagged bonefish were detected for more than two weeks. A comparison of the final 100 hours of movement data from fish that were detected for less than two weeks to fish detected for longer periods revealed distinct differences. These included differences in area use patterns and significant differences in the average daily distance moved, speed of movement and residency index. This suggested that mortality in the form of post-release predation was high (90%) with tagged fish detected for less than two weeks being preyed upon by sharks. The three surviving bonefish were tracked for 210 to 367 days. These individuals remained in the atoll and showed high use of the marginal habitats between the shallow sand flats and the deeper lagoon. Water temperature, diel cycle and tide were significant predictors of bonefish presence in the lagoon. The high post-release predation of bonefish has implications for the management of this and other Albula species. Despite these fisheries being catch-and-release, bonefish fishing may be unsustainable due to the high post-release mortality, particularly in areas that are rich in predators. Therefore, protected areas or limitations on fishing effort need to be considered.
- Full Text:
- Date Issued: 2018
An evaluation of the impact of the biogas digesters project at Melani village, Eastern Cape, South Africa
- Authors: Mthimunye , Thabiso Vincent
- Date: 2018
- Subjects: Biogas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14561 , vital:40014
- Description: A study was conducted in Melani rural community of Raymond Mhlaba district in Eastern Cape, with the aim of identifying types of energy sources and households energy utilization. Melani village (32°43’29” S, 27°07’35” E) is 13 km away from Alice, the closest town and its household population is about 350. The survey was conducted with 50% of the randomly chosen households using semi-structured questionnaires and some onset CTA-A hobo current transducers were installed in three households to measure electricity used for either cooking, heating or lighting. The survey shows that electricity (supplied by Eskom) is the main source of energy for cooking, lighting and heating, while paraffin and candles are also used for lighting. The data collected using the data acquisition system has also shown that each household consumes an average of 140 kWh of electricity per month. Assuming this amount of energy being used throughout the year, on average the households consume 1680 kWh of electricity per year. The research concludes that there is a need to promote sustainable energy resources and technologies such as the use of biogas digesters as an alternative source of energy since the households has on average 20 of cattle, 10 of goats, 10 sheep and 4 donkeys. The research has also shown that the economic analysis of the biogas project is financially feasible. The Net present value was high and positive showing the feasibility of the investment on the project. The payback period was implying that the project pays itself off within the service life or within a set payback limit, which must be shorter than the technical service period of 5 years. The research has further shown that the emission factor for carbon dioxide for every 1MWh of electrical energy saved is 1.07 kg and consequently a corresponding volume of avoidance water is 1.40 KL. This can be mentioned that this monthly cost saving in the electrical energy consumption can go a long way in improving the social and economic welfare of the people. More so, it also vi plays a key role in the reduction of the global warming potential and the amount of air pollutant in the atmosphere. The avoidance water also contributed greatly in reducing the total volume of water used in the cooling towers of the coal power generation plant.
- Full Text:
- Date Issued: 2018
- Authors: Mthimunye , Thabiso Vincent
- Date: 2018
- Subjects: Biogas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14561 , vital:40014
- Description: A study was conducted in Melani rural community of Raymond Mhlaba district in Eastern Cape, with the aim of identifying types of energy sources and households energy utilization. Melani village (32°43’29” S, 27°07’35” E) is 13 km away from Alice, the closest town and its household population is about 350. The survey was conducted with 50% of the randomly chosen households using semi-structured questionnaires and some onset CTA-A hobo current transducers were installed in three households to measure electricity used for either cooking, heating or lighting. The survey shows that electricity (supplied by Eskom) is the main source of energy for cooking, lighting and heating, while paraffin and candles are also used for lighting. The data collected using the data acquisition system has also shown that each household consumes an average of 140 kWh of electricity per month. Assuming this amount of energy being used throughout the year, on average the households consume 1680 kWh of electricity per year. The research concludes that there is a need to promote sustainable energy resources and technologies such as the use of biogas digesters as an alternative source of energy since the households has on average 20 of cattle, 10 of goats, 10 sheep and 4 donkeys. The research has also shown that the economic analysis of the biogas project is financially feasible. The Net present value was high and positive showing the feasibility of the investment on the project. The payback period was implying that the project pays itself off within the service life or within a set payback limit, which must be shorter than the technical service period of 5 years. The research has further shown that the emission factor for carbon dioxide for every 1MWh of electrical energy saved is 1.07 kg and consequently a corresponding volume of avoidance water is 1.40 KL. This can be mentioned that this monthly cost saving in the electrical energy consumption can go a long way in improving the social and economic welfare of the people. More so, it also vi plays a key role in the reduction of the global warming potential and the amount of air pollutant in the atmosphere. The avoidance water also contributed greatly in reducing the total volume of water used in the cooling towers of the coal power generation plant.
- Full Text:
- Date Issued: 2018
Biophysical monitoring of unphosphorylated STAT3 homodimerization
- Mtwebana, Sinethemba Siphokazi
- Authors: Mtwebana, Sinethemba Siphokazi
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63957 , vital:28514
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Mtwebana, Sinethemba Siphokazi
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63957 , vital:28514
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Assessment of pharmaceutical equivalence of topical cream products containing hydrocortisone acetate using in vitro release testing (IVRT)
- Mudyahoto, Nyengeterai Amanda
- Authors: Mudyahoto, Nyengeterai Amanda
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63384 , vital:28404
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Mudyahoto, Nyengeterai Amanda
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63384 , vital:28404
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Formulation, characterisation and optimisation of self-nanoemulsifying drug delivery systems (SNEDDS) loaded with artemether and lumefantrine
- Authors: Mudyahoto, Tsitsi
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63503 , vital:28422
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Mudyahoto, Tsitsi
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63503 , vital:28422
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Preparation, characterization and in vitro analysis of polyamidoamine drug conjugates containing ferrocene and platinum analogues
- Authors: Mugogodi, Ansley
- Date: 2018
- Subjects: Ferrocene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10145 , vital:35360
- Description: Polyamidoamine drug conjugates were prepared from analogues of ferrocene and platinum. Standard reaction procedures were followed in the synthesis of platinum and ferrocene analogues. Michael addition reaction of amines to the activated double bonds of methylenebisacrylamide was applied for preparation of the water soluble polyamidoamine carriers onto which drug analogues were attached. The drug release studies of the conjugates were evaluated at different pH environments. The results obtained from drug release studies showed that rate of drug release was variable depending on the conjugate and pH environment. Mathematical drug release models by Korsmeyer-Peppas were used to determine the drug release characteristics of the ferrocene and platinum based drugs from polyamidoamine drug conjugates. Cytotoxicity potential of the analogues and polyamidoamine drug conjugates was tested on selected cell lines. Cisplatin was used as the standard for comparison of the IC50 values obtained for the compounds tested for cytotoxicity activity. The results from six polymer drug conjugates tested for cytotoxicity activity showed that conjugation of analogues to polyamidoamine carrier enhanced the activity of the analogues in some of the polyamidoamine drug conjugates. Various techniques such as Fourier Transform Infrared (FTIR) spectroscopy, Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX) spectroscopy were employed for the characterization of the ferrocene and platinum analogues, polyamidoamine carriers and drug conjugates.
- Full Text:
- Date Issued: 2018
- Authors: Mugogodi, Ansley
- Date: 2018
- Subjects: Ferrocene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10145 , vital:35360
- Description: Polyamidoamine drug conjugates were prepared from analogues of ferrocene and platinum. Standard reaction procedures were followed in the synthesis of platinum and ferrocene analogues. Michael addition reaction of amines to the activated double bonds of methylenebisacrylamide was applied for preparation of the water soluble polyamidoamine carriers onto which drug analogues were attached. The drug release studies of the conjugates were evaluated at different pH environments. The results obtained from drug release studies showed that rate of drug release was variable depending on the conjugate and pH environment. Mathematical drug release models by Korsmeyer-Peppas were used to determine the drug release characteristics of the ferrocene and platinum based drugs from polyamidoamine drug conjugates. Cytotoxicity potential of the analogues and polyamidoamine drug conjugates was tested on selected cell lines. Cisplatin was used as the standard for comparison of the IC50 values obtained for the compounds tested for cytotoxicity activity. The results from six polymer drug conjugates tested for cytotoxicity activity showed that conjugation of analogues to polyamidoamine carrier enhanced the activity of the analogues in some of the polyamidoamine drug conjugates. Various techniques such as Fourier Transform Infrared (FTIR) spectroscopy, Proton Nuclear Magnetic Resonance spectroscopy (1H NMR), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX) spectroscopy were employed for the characterization of the ferrocene and platinum analogues, polyamidoamine carriers and drug conjugates.
- Full Text:
- Date Issued: 2018