Nanofiber immobilized cellulases and hemicellulases for fruit waste beneficiation
- Authors: Swart, Shanna
- Date: 2015
- Subjects: Agricultural wastes , Cellulase , Hemicellulose , Nanofibers , Electrospinning , Lignocellulose -- Biodegradation , Biomass conversion , Polysaccharides , Immobilized enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4153 , http://hdl.handle.net/10962/d1017914
- Full Text:
- Date Issued: 2015
- Authors: Swart, Shanna
- Date: 2015
- Subjects: Agricultural wastes , Cellulase , Hemicellulose , Nanofibers , Electrospinning , Lignocellulose -- Biodegradation , Biomass conversion , Polysaccharides , Immobilized enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4153 , http://hdl.handle.net/10962/d1017914
- Full Text:
- Date Issued: 2015
The interaction of silver nanoparticles with triosephosphate isomerase from human and malarial parasite (Plasmodium falciparum) : a comparative study
- De Moor, Warren Ralph Josephus
- Authors: De Moor, Warren Ralph Josephus
- Date: 2014
- Subjects: Silver , Nanoparticles , Triose-phosphate isomerase , Plasmodium falciparum , Nanotechnology , Antimalarials , Povidone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4169 , http://hdl.handle.net/10962/d1020895
- Description: The advent of advanced modern nanotechnology techniques offers new and exciting opportunities to develop novel nanotech-derived antimalarial nanodrugs with enhanced selective and targeting abilities that allow for lower effective drug dosages, longer drug persistence and reduced drug degradation within the body. Using a nanodrug approach also has the advantage of avoiding drug resistance problems that plague reconfigured versions of already-existing antimalarial drugs. In this study recombinant triosephosphate isomerase enzymes from Plasmodium falciparum (PfTIM) and Humans (hTIM) were recombinantly expressed, purified and characterised. PfTIM was shown to have optimal pH stability at pH 5.0-5.5 and thermal stability at 25°C with Km 4.34 mM and Vmax 0.876 μmol.ml⁻ₑmin⁻ₑ. For hTIM, these parameters were as follows: pH optima of 6.5-7.0; temperature optima of 30°C, with Km 2.27 mM and Vmax 0.714 μmol.ml⁻ₑmin⁻ₑ. Recombinant TIM enzymes were subjected to inhibition studies using polyvinylpyrrolidone (PVP) stabilised silver nanoparticles (AgNPs) of 4-12 nm in diameter. These studies showed that the AgNPs were able to selectively inhibit PfTIM over hTIM with an 8-fold greater decrease in enzymatic efficiency (Kcat/Km) observed for PfTIM, as compared to hTIM, for kinetics tests done using 0.06 μM of AgNPs. Complete inhibition of PfTIM under optimal conditions was achieved using 0.25 μM AgNPs after 45 minutes while hTIM maintained approximately 31% of its activity at this AgNP concentration. The above results indicate that selective enzymatic targeting of the important, key metabolic enzyme TIM, can be achieved using nanotechnology-derived nanodrugs. It was demonstrated that the key structural differences, between the two enzyme variants, were significant enough to create unique characteristics for each TIM variant, thereby allowing for selective enzyme targeting using AgNPs. If these AgNPs could be coupled with a nanotechnology-derived, targeted localization mechanism – possibly using apoferritin to deliver the AgNPs to infected erythrocytes (Burns and Pollock, 2008) – then such an approach could offer new opportunities for the development of viable antimalarial nanodrugs. For this to be achieved further research into several key areas will be required, including nanoparticle toxicity, drug localization and testing the lethality of the system on live parasite cultures.
- Full Text:
- Date Issued: 2014
- Authors: De Moor, Warren Ralph Josephus
- Date: 2014
- Subjects: Silver , Nanoparticles , Triose-phosphate isomerase , Plasmodium falciparum , Nanotechnology , Antimalarials , Povidone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4169 , http://hdl.handle.net/10962/d1020895
- Description: The advent of advanced modern nanotechnology techniques offers new and exciting opportunities to develop novel nanotech-derived antimalarial nanodrugs with enhanced selective and targeting abilities that allow for lower effective drug dosages, longer drug persistence and reduced drug degradation within the body. Using a nanodrug approach also has the advantage of avoiding drug resistance problems that plague reconfigured versions of already-existing antimalarial drugs. In this study recombinant triosephosphate isomerase enzymes from Plasmodium falciparum (PfTIM) and Humans (hTIM) were recombinantly expressed, purified and characterised. PfTIM was shown to have optimal pH stability at pH 5.0-5.5 and thermal stability at 25°C with Km 4.34 mM and Vmax 0.876 μmol.ml⁻ₑmin⁻ₑ. For hTIM, these parameters were as follows: pH optima of 6.5-7.0; temperature optima of 30°C, with Km 2.27 mM and Vmax 0.714 μmol.ml⁻ₑmin⁻ₑ. Recombinant TIM enzymes were subjected to inhibition studies using polyvinylpyrrolidone (PVP) stabilised silver nanoparticles (AgNPs) of 4-12 nm in diameter. These studies showed that the AgNPs were able to selectively inhibit PfTIM over hTIM with an 8-fold greater decrease in enzymatic efficiency (Kcat/Km) observed for PfTIM, as compared to hTIM, for kinetics tests done using 0.06 μM of AgNPs. Complete inhibition of PfTIM under optimal conditions was achieved using 0.25 μM AgNPs after 45 minutes while hTIM maintained approximately 31% of its activity at this AgNP concentration. The above results indicate that selective enzymatic targeting of the important, key metabolic enzyme TIM, can be achieved using nanotechnology-derived nanodrugs. It was demonstrated that the key structural differences, between the two enzyme variants, were significant enough to create unique characteristics for each TIM variant, thereby allowing for selective enzyme targeting using AgNPs. If these AgNPs could be coupled with a nanotechnology-derived, targeted localization mechanism – possibly using apoferritin to deliver the AgNPs to infected erythrocytes (Burns and Pollock, 2008) – then such an approach could offer new opportunities for the development of viable antimalarial nanodrugs. For this to be achieved further research into several key areas will be required, including nanoparticle toxicity, drug localization and testing the lethality of the system on live parasite cultures.
- Full Text:
- Date Issued: 2014
A review of lessons learned to inform capacity-building for sustainable nature-based tourism development in the European Union funded ʺSupport to the Wild Coast Spatial Development Initiative Pilot Programmeʺ
- Authors: Wright, Brian Bradley
- Date: 2006
- Subjects: Wild Coast Spatial Development Initiative Pilot Programme , Sustainable development -- South Africa -- Eastern Cape -- Citizen participation , Sustainable development -- Environmental aspects -- South Africa -- Eastern Cape , Conservation and natural resources -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Natural resources -- Management -- International cooperation , Rural development -- South Africa -- Eastern Cape , Eastern Cape (South Africa) -- Economic development , South Africa -- Foreign economic relations -- European Union countries , European Union countries -- Foreign economic relations -- South Africa , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Tourism -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1744 , http://hdl.handle.net/10962/d1003628 , Wild Coast Spatial Development Initiative Pilot Programme , Sustainable development -- South Africa -- Eastern Cape -- Citizen participation , Sustainable development -- Environmental aspects -- South Africa -- Eastern Cape , Conservation and natural resources -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Natural resources -- Management -- International cooperation , Rural development -- South Africa -- Eastern Cape , Eastern Cape (South Africa) -- Economic development , South Africa -- Foreign economic relations -- European Union countries , European Union countries -- Foreign economic relations -- South Africa , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Tourism -- Environmental aspects -- South Africa -- Eastern Cape
- Description: This case-study establishes the influences of power-knowledge relationships on capacity-building for sustainability in the European Union Funded ‘Wild Coast Spatial Development Initiative Pilot Programme’ (EU Programme). It aims to capture the lessons learned for capacitybuilding to support nature-based tourism initiatives on the Wild Coast. The EU Programme aimed to achieve economic and social development of previously disadvantaged communities through nature-based tourism enterprises, and to develop capacity of local authorities and communities to support environmental management. The study discusses common trends in thematic categories emerging from the research data, and contextualises research findings in a broader development landscape. This study indicates that power-knowledge relations were reflected in the EU Programme’s development ideology by an exclusionary development approach, which lacked a participatory ethos. This exclusionary approach did not support an enabling environment for capacity-building. This development approach, guiding the programme conceptualization, design and implementation processes, resulted in a programme with unrealistic objectives, time-frames and resource allocations; a programme resisted by provincial and local government. The study provides a causal link between participation, programme relevance, programme ownership, commitment of stakeholders, effective management and capacity-building for sustainable programme implementation. The study argues that the underlying motivation for the exclusionary EU development ideology in the programme is driven by a risk management strategy. This approach allows the EU to hold power in the development process, whereas, an inclusionary participative development methodology would require a more in-depth negotiation with stakeholders, thereby requiring the EU to relinquish existing levels of power and control. This may increase the risk of an unexpected programme design outcome and associated exposure to financial risk. It may also have a significant financial effect on donor countries' consultancies and consultants currently driving the development industry. This study recommends an interactive-participative methodology for programme design and implementation, if an enabling environment for capacity-building is to be created. In addition, all programme stakeholders must share contractual accountability for programme outcomes. This requires a paradigm shift in the EU development ideology to an inclusionary methodology. However, this research suggests that the current EU development approach will not voluntarily change. I, therefore, argue that South Africa needs to develop a legislative framework that will guide donor-funded development programme methodology, to support an enabling environment for capacity-building.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Brian Bradley
- Date: 2006
- Subjects: Wild Coast Spatial Development Initiative Pilot Programme , Sustainable development -- South Africa -- Eastern Cape -- Citizen participation , Sustainable development -- Environmental aspects -- South Africa -- Eastern Cape , Conservation and natural resources -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Natural resources -- Management -- International cooperation , Rural development -- South Africa -- Eastern Cape , Eastern Cape (South Africa) -- Economic development , South Africa -- Foreign economic relations -- European Union countries , European Union countries -- Foreign economic relations -- South Africa , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Tourism -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1744 , http://hdl.handle.net/10962/d1003628 , Wild Coast Spatial Development Initiative Pilot Programme , Sustainable development -- South Africa -- Eastern Cape -- Citizen participation , Sustainable development -- Environmental aspects -- South Africa -- Eastern Cape , Conservation and natural resources -- South Africa -- Eastern Cape , Natural resources -- Management -- South Africa -- Eastern Cape , Natural resources -- Management -- International cooperation , Rural development -- South Africa -- Eastern Cape , Eastern Cape (South Africa) -- Economic development , South Africa -- Foreign economic relations -- European Union countries , European Union countries -- Foreign economic relations -- South Africa , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Tourism -- Environmental aspects -- South Africa -- Eastern Cape
- Description: This case-study establishes the influences of power-knowledge relationships on capacity-building for sustainability in the European Union Funded ‘Wild Coast Spatial Development Initiative Pilot Programme’ (EU Programme). It aims to capture the lessons learned for capacitybuilding to support nature-based tourism initiatives on the Wild Coast. The EU Programme aimed to achieve economic and social development of previously disadvantaged communities through nature-based tourism enterprises, and to develop capacity of local authorities and communities to support environmental management. The study discusses common trends in thematic categories emerging from the research data, and contextualises research findings in a broader development landscape. This study indicates that power-knowledge relations were reflected in the EU Programme’s development ideology by an exclusionary development approach, which lacked a participatory ethos. This exclusionary approach did not support an enabling environment for capacity-building. This development approach, guiding the programme conceptualization, design and implementation processes, resulted in a programme with unrealistic objectives, time-frames and resource allocations; a programme resisted by provincial and local government. The study provides a causal link between participation, programme relevance, programme ownership, commitment of stakeholders, effective management and capacity-building for sustainable programme implementation. The study argues that the underlying motivation for the exclusionary EU development ideology in the programme is driven by a risk management strategy. This approach allows the EU to hold power in the development process, whereas, an inclusionary participative development methodology would require a more in-depth negotiation with stakeholders, thereby requiring the EU to relinquish existing levels of power and control. This may increase the risk of an unexpected programme design outcome and associated exposure to financial risk. It may also have a significant financial effect on donor countries' consultancies and consultants currently driving the development industry. This study recommends an interactive-participative methodology for programme design and implementation, if an enabling environment for capacity-building is to be created. In addition, all programme stakeholders must share contractual accountability for programme outcomes. This requires a paradigm shift in the EU development ideology to an inclusionary methodology. However, this research suggests that the current EU development approach will not voluntarily change. I, therefore, argue that South Africa needs to develop a legislative framework that will guide donor-funded development programme methodology, to support an enabling environment for capacity-building.
- Full Text:
- Date Issued: 2006
Nutrient dynamics in and offshore of two permanently open South African estuaries with contrasting fresh water inflow
- Authors: Jennings, Michael Evan
- Date: 2006
- Subjects: Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5735 , http://hdl.handle.net/10962/d1005421 , Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
- Description: The nutrient dynamics in two contrasting estuaries and in the adjacent nearshore environment along the south-east coast of South Africa was investigated seasonally. Due to an inter-basin transfer of water from the Gariep Dam to the Great Fish River, the Great Fish estuary is a fresh water dominated, terrestrially driven system with an annual fresh water inflow of 250 – 650 x 10⁶ m³ per year. In contrast, the Kariega estuary is a fresh water deprived, marine dominated system with a fresh water inflow estimated at 2.5 – 35 x 10⁶ m³per year. The reduced fresh water inflow into the estuary is attributed to regular impoundments along the Kariega River. Water samples were collected from surface and subsurface layers along the length of the estuaries as well as from a series of transects occupied in the nearshore environment. Samples were analysed for nitrate, nitrite, ammonium, phosphate and silicate. Temperature and salinity were recorded at each station. A Land-Ocean Interactions in the Coastal Zone (LOICZ) budget was constructed for each estuary to describe the role of ecosystem-level metabolism as either a sink or a source of phosphorus, nitrogen and carbon. Seasonal variation in physico-chemical properties and nutrient concentrations in the Kariega estuary was minimal due to constant low inflow, while in the Great Fish estuary, concentrations varied in response to changes in flow rate. Nutrient concentrations were consistently higher in the Great Fish estuary than in the Kariega estuary, largely reflecting differences in fresh water inflow. During periods of high flow (32.92 m³.s⁻¹in the Great Fish River) dissolved inorganic nitrogen (DIN) concentrations in the Great Fish estuary were an order of magnitude higher than those recorded in the Kariega estuary. Results of the LOICZ budgeting procedures revealed that in spite of the contrasting hydrodynamic features, the estuaries behave in largely the same manner – both predominantly sources of nutrients with heterotrophic processes dominating over autotrophic actions and both were net denitrifyers during all surveys. This was, however, due to different sets of processes operating in the two estuaries, namely low nutrient concentrations resulting in microbial activity in the Kariega estuary, and riverine influx of nutrients and phytoplankton combined with a short residence time of the water in the Great Fish estuary. In the marine nearshore environment, higher nutrient concentrations were recorded adjacent to the Great Fish estuary than offshore of the Kariega estuary. This was due to a surface plume of less saline water leaving the Great Fish estuary, which acted as an ‘outweller’ of nutrients. Offshore of the Kariega estuary, on the other hand, the nutrient concentrations were characteristic of marine waters due to a lack of fresh water outflow from the estuary. Nutrient concentrations in the marine environment adjacent to the Kariega estuary were, at times, higher than those recorded within the estuary. This observation supports previous statements which suggest that the Kariega estuary is not an ‘outweller’ of dissolved nutrients and particulate material, but rather an extension of the marine environment.
- Full Text:
- Date Issued: 2006
- Authors: Jennings, Michael Evan
- Date: 2006
- Subjects: Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5735 , http://hdl.handle.net/10962/d1005421 , Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
- Description: The nutrient dynamics in two contrasting estuaries and in the adjacent nearshore environment along the south-east coast of South Africa was investigated seasonally. Due to an inter-basin transfer of water from the Gariep Dam to the Great Fish River, the Great Fish estuary is a fresh water dominated, terrestrially driven system with an annual fresh water inflow of 250 – 650 x 10⁶ m³ per year. In contrast, the Kariega estuary is a fresh water deprived, marine dominated system with a fresh water inflow estimated at 2.5 – 35 x 10⁶ m³per year. The reduced fresh water inflow into the estuary is attributed to regular impoundments along the Kariega River. Water samples were collected from surface and subsurface layers along the length of the estuaries as well as from a series of transects occupied in the nearshore environment. Samples were analysed for nitrate, nitrite, ammonium, phosphate and silicate. Temperature and salinity were recorded at each station. A Land-Ocean Interactions in the Coastal Zone (LOICZ) budget was constructed for each estuary to describe the role of ecosystem-level metabolism as either a sink or a source of phosphorus, nitrogen and carbon. Seasonal variation in physico-chemical properties and nutrient concentrations in the Kariega estuary was minimal due to constant low inflow, while in the Great Fish estuary, concentrations varied in response to changes in flow rate. Nutrient concentrations were consistently higher in the Great Fish estuary than in the Kariega estuary, largely reflecting differences in fresh water inflow. During periods of high flow (32.92 m³.s⁻¹in the Great Fish River) dissolved inorganic nitrogen (DIN) concentrations in the Great Fish estuary were an order of magnitude higher than those recorded in the Kariega estuary. Results of the LOICZ budgeting procedures revealed that in spite of the contrasting hydrodynamic features, the estuaries behave in largely the same manner – both predominantly sources of nutrients with heterotrophic processes dominating over autotrophic actions and both were net denitrifyers during all surveys. This was, however, due to different sets of processes operating in the two estuaries, namely low nutrient concentrations resulting in microbial activity in the Kariega estuary, and riverine influx of nutrients and phytoplankton combined with a short residence time of the water in the Great Fish estuary. In the marine nearshore environment, higher nutrient concentrations were recorded adjacent to the Great Fish estuary than offshore of the Kariega estuary. This was due to a surface plume of less saline water leaving the Great Fish estuary, which acted as an ‘outweller’ of nutrients. Offshore of the Kariega estuary, on the other hand, the nutrient concentrations were characteristic of marine waters due to a lack of fresh water outflow from the estuary. Nutrient concentrations in the marine environment adjacent to the Kariega estuary were, at times, higher than those recorded within the estuary. This observation supports previous statements which suggest that the Kariega estuary is not an ‘outweller’ of dissolved nutrients and particulate material, but rather an extension of the marine environment.
- Full Text:
- Date Issued: 2006
Adaptive flow management of multimedia data with a variable quality of service
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
An experimental study of the effect of Acacia mearnsii (black wattle trees) on streamflow in the Sand River, Eastern Cape
- Authors: Beyers, Gregory John
- Date: 1999
- Subjects: Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4832 , http://hdl.handle.net/10962/d1005507 , Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Description: This thesis explores the effect of Acacia mearnsii on streamflow in the Eastern Cape. There is a need for data on the localised effects of removing alien trees from the riparian zones within the Fynbos Biome. Fynbos catchments throughout the Western and Eastern Cape yield large quantities of good quality water which is an essential resource in the region. To convince local land owners to manage their riparian zones, small scale experimental results will prove invaluable to assure them of the immediate advantages for themselves and for downstream water users. Three permanent weirs were built 500 m apart to monitor the effect of removing A. mearnsii on streamflow in the Sand River, Eastern Cape. Consecutive weirs allowed for the comparison of streamflow between a cleared and uncleared section of the river without significant differences in riparian conditions, channel morphology and vegetation densities. A site survey confirmed comparable densities of A. mearnsii in both sections. A sample of trees was weighed and a relationship was found between diameter at breast height and above ground wet biomass. Between the first two weirs, 2.5 ha of riparian zone was cleared amounting to approximately 160tlha. Streamflow was monitored from the 10th of January 1996 to the 9th of September 1996. The average streamflow reduction for the duration of the experiment was 15.1 m³/ha/day or 551 mm per annum. Initially, after a period of above average rainfall, streamflow was augmented by discharge from the riparian zone but as conditions dried out, there was a net uptake of water with the highest average uptake of 23. 7m³/ha/day in June. A comparison between weather conditions and streamflow reduction indicated there is a complex relationship, with evidence of A. mearnsii exhibiting control of water loss during dry conditions. Acacia mearnsii trees in the riparian zone have been shown to cause significant streamflow reduction. Permanent weirs were found to be appropriate for this type of study. There is a need for further research on the effect of alien trees in riparian zones around South Africa as there is potential for significant increases in streamflow.
- Full Text:
- Date Issued: 1999
- Authors: Beyers, Gregory John
- Date: 1999
- Subjects: Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4832 , http://hdl.handle.net/10962/d1005507 , Wattles (Plants) -- South Africa , Wattles (Plants) -- South Africa -- Eastern Cape , Sand river (South africa) , Streamflow , Streamflow -- South Africa
- Description: This thesis explores the effect of Acacia mearnsii on streamflow in the Eastern Cape. There is a need for data on the localised effects of removing alien trees from the riparian zones within the Fynbos Biome. Fynbos catchments throughout the Western and Eastern Cape yield large quantities of good quality water which is an essential resource in the region. To convince local land owners to manage their riparian zones, small scale experimental results will prove invaluable to assure them of the immediate advantages for themselves and for downstream water users. Three permanent weirs were built 500 m apart to monitor the effect of removing A. mearnsii on streamflow in the Sand River, Eastern Cape. Consecutive weirs allowed for the comparison of streamflow between a cleared and uncleared section of the river without significant differences in riparian conditions, channel morphology and vegetation densities. A site survey confirmed comparable densities of A. mearnsii in both sections. A sample of trees was weighed and a relationship was found between diameter at breast height and above ground wet biomass. Between the first two weirs, 2.5 ha of riparian zone was cleared amounting to approximately 160tlha. Streamflow was monitored from the 10th of January 1996 to the 9th of September 1996. The average streamflow reduction for the duration of the experiment was 15.1 m³/ha/day or 551 mm per annum. Initially, after a period of above average rainfall, streamflow was augmented by discharge from the riparian zone but as conditions dried out, there was a net uptake of water with the highest average uptake of 23. 7m³/ha/day in June. A comparison between weather conditions and streamflow reduction indicated there is a complex relationship, with evidence of A. mearnsii exhibiting control of water loss during dry conditions. Acacia mearnsii trees in the riparian zone have been shown to cause significant streamflow reduction. Permanent weirs were found to be appropriate for this type of study. There is a need for further research on the effect of alien trees in riparian zones around South Africa as there is potential for significant increases in streamflow.
- Full Text:
- Date Issued: 1999
A study of the Pycnonotus bulbul species complex in Southern Africa
- Authors: Lloyd, Penn
- Date: 1995
- Subjects: Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5782 , http://hdl.handle.net/10962/d1005470 , Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Description: The three Pycnonotus bulbuls endemic to Africa, P. barbatus, P. nigricans and P. capensis, occupy mutually exclusive distributions in southern Africa. These species are closely related and appear to occupy very similar ecological niches, only in different regions. Using a multifaceted approach, this study attempts to explain the ecology of this species complex. All three species show similar physiological responses to temperature extremes, and are therefore unlikely to be directly limited by environmental temperature. However, their distributions are highly correlated to a complex of environmental variables, particularly winter minimum temperatures, the coefficient of variation in mean annual rainfall, and the seasonality of rainfall. This combination of environmental parameters can be used to predict the distributions of at least one of the species, P. nigricans, accurately. An analysis of the vocalizations and behaviour of the three species revealed that, whilst P. capensis has a number of recognizably different vocalizations, those of P. barbatus and P. nigricans are very similar. The three have nearly identical behaviours, particularly courtship and pre-copulatory behaviours. The mate recognition systems of the three are therefore extremely similar. P. barbatus is territorial during the breeding season, and exhibits highly structured-variation in male territorial song at the level of the local neighbourhood. The literature pertaining to song dialects is reviewed, and a new hypothesis is postulated to explain song-matching in terms of neighbour/stranger discrimination and the possible existence of cooperative territory defence. A survey of the eastern Cape region, where all three species come into contact, showed that extensive hybridization is taking place between each species pair. Phenotypically, this hybridization is restricted to narrow hybrid zones, that are considered to be stable in both time and place. The evolutionary and ecological significance of these zones to the distributions of the species is discussed, and it is proposed that the zones are maintained by selection acting on differentially-adapted genomes along an environmental gradient.
- Full Text:
- Date Issued: 1995
- Authors: Lloyd, Penn
- Date: 1995
- Subjects: Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5782 , http://hdl.handle.net/10962/d1005470 , Bulbuls -- Ecology -- South Africa -- Eastern Cape , Songbirds -- Ecology -- South Africa -- Eastern Cape , Birds -- Ecology -- South Africa -- Eastern Cape
- Description: The three Pycnonotus bulbuls endemic to Africa, P. barbatus, P. nigricans and P. capensis, occupy mutually exclusive distributions in southern Africa. These species are closely related and appear to occupy very similar ecological niches, only in different regions. Using a multifaceted approach, this study attempts to explain the ecology of this species complex. All three species show similar physiological responses to temperature extremes, and are therefore unlikely to be directly limited by environmental temperature. However, their distributions are highly correlated to a complex of environmental variables, particularly winter minimum temperatures, the coefficient of variation in mean annual rainfall, and the seasonality of rainfall. This combination of environmental parameters can be used to predict the distributions of at least one of the species, P. nigricans, accurately. An analysis of the vocalizations and behaviour of the three species revealed that, whilst P. capensis has a number of recognizably different vocalizations, those of P. barbatus and P. nigricans are very similar. The three have nearly identical behaviours, particularly courtship and pre-copulatory behaviours. The mate recognition systems of the three are therefore extremely similar. P. barbatus is territorial during the breeding season, and exhibits highly structured-variation in male territorial song at the level of the local neighbourhood. The literature pertaining to song dialects is reviewed, and a new hypothesis is postulated to explain song-matching in terms of neighbour/stranger discrimination and the possible existence of cooperative territory defence. A survey of the eastern Cape region, where all three species come into contact, showed that extensive hybridization is taking place between each species pair. Phenotypically, this hybridization is restricted to narrow hybrid zones, that are considered to be stable in both time and place. The evolutionary and ecological significance of these zones to the distributions of the species is discussed, and it is proposed that the zones are maintained by selection acting on differentially-adapted genomes along an environmental gradient.
- Full Text:
- Date Issued: 1995
The effect of the pesticide, endosulfan, on hepatic cytochrome P-450, liver and gill ultrastructure, and selected haematological parameters of Oreochromis Mossambicus (Peters, 1852) (Pisces : Cichlidae)
- Authors: Quick, Arthur Joseph Rex
- Date: 1986
- Subjects: Pesticides , Mozambique tilapia , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5195 , http://hdl.handle.net/10962/d1001971 , Pesticides , Mozambique tilapia , Cichlids
- Description: Two possible ways in which fish may acclimate to prolonged exposure· to sublethal levels of endosulfan were investigated: induction of the hepatic monooxygenase system and changes in haematology. These studies also involved an examination of the ultrastructure of liver and gill tissue. Endosulfan caused none of the characteristic phenobarbital-type inductive effects on the liver of Oreochromis mossambicus. There was no increase in cytochrome P-450 levels, microsomal protein or hepatosomatic index. The reasons for the lack of induction are discussed. The effect of endosulfan on the following haematological parameters was determined: haemoglobin, erythrocyte count, microhaematocrit, mean erythrocyte volume and mean erythrocyte haemoglobin concentration. The only effect was an increase in erythrocyte count. The value of changes in haematological parameters as indicators of pollutioninduced anemia in the field is discussed. No changes in gill ultrastructure were noted although electron micrographs of liver tissue showed lesions in hepatocytes. The diagnostic value of pollution-induced pathological changes on cell ultrastructure are discussed. Recommendations are made with regard to future large scale application of pesticides on or near large water bodies
- Full Text:
- Date Issued: 1986
- Authors: Quick, Arthur Joseph Rex
- Date: 1986
- Subjects: Pesticides , Mozambique tilapia , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5195 , http://hdl.handle.net/10962/d1001971 , Pesticides , Mozambique tilapia , Cichlids
- Description: Two possible ways in which fish may acclimate to prolonged exposure· to sublethal levels of endosulfan were investigated: induction of the hepatic monooxygenase system and changes in haematology. These studies also involved an examination of the ultrastructure of liver and gill tissue. Endosulfan caused none of the characteristic phenobarbital-type inductive effects on the liver of Oreochromis mossambicus. There was no increase in cytochrome P-450 levels, microsomal protein or hepatosomatic index. The reasons for the lack of induction are discussed. The effect of endosulfan on the following haematological parameters was determined: haemoglobin, erythrocyte count, microhaematocrit, mean erythrocyte volume and mean erythrocyte haemoglobin concentration. The only effect was an increase in erythrocyte count. The value of changes in haematological parameters as indicators of pollutioninduced anemia in the field is discussed. No changes in gill ultrastructure were noted although electron micrographs of liver tissue showed lesions in hepatocytes. The diagnostic value of pollution-induced pathological changes on cell ultrastructure are discussed. Recommendations are made with regard to future large scale application of pesticides on or near large water bodies
- Full Text:
- Date Issued: 1986
Some aspects of the biology of Nassarius kraussianus (Dunker)(Gastropoda : Prosobranchia : Nassariidae), in the Bushman's River estuary, with particular reference to recolonisation after floods
- Authors: Palmer, Carolyn Gay
- Date: 1981
- Subjects: Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5809 , http://hdl.handle.net/10962/d1006934 , Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Description: 1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.
- Full Text:
- Date Issued: 1981
- Authors: Palmer, Carolyn Gay
- Date: 1981
- Subjects: Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5809 , http://hdl.handle.net/10962/d1006934 , Gastropoda -- South Africa -- Eastern Cape , Estuarine biology -- South Africa -- Eastern Cape , Prosobranchia -- South Africa -- Eastern Cape
- Description: 1. The development of estuarine research in South Africa has been reviewed, and the present state of knowledge assessed. Little is known about many abundant estuarine species, and a previously unstudied prosobranch Nassarius kraussianus (Dunker), was selected for investigation. 2. The study area, a mudflat on the Bushmans River estuary, was divided into three habitat types: supratidal, intertidal and subtidal, each with a particular substratum and pattern of vegetation cover. The distribution of N. kraussianus is associated with the nature of the substratum and the degree of Zostera capensis Setchell cover. 3. A brief review of pertinent literature indicated the necessity of relating population parameters to environmental conditions. 4. The population biology of N. . kraussianus was investigated, and the size frequencies, sex ratios, and male/female size frequencies were recorded over three distinct periods: pre-flood, post-flood and recovery. 5. The Bushmans River flooded in July and August 1979, and the results of the flood have been described. The most immediate result was a period of low salinity, but the most persistant result was the deposition of silt, which had an important effect on the substratum and the Z. capensis beds. 6. The pre-flood population was characterised by patchy distribution, and by a large number of mature adults in relation to juveniles. Females were generally larger than males, and the sex ratio was 1:1. The presence of juveniles in consistantly low numbers indicated that reproduction may have been continuous, but that intraspecific adult/juvenile competition may have kept juvenile numbers low. 7. The post-flood period was characterised by extreme physical conditions, and the survival of a few adults. Juveniles were completely annihilated, and were absent until a few were spawned by the surviving adults towards the end of 1979 . Sex ratio was biased, and females predominated. 8. The recovery period began abruptly with the arrival of a large number of juveniles in the 2, 3 and 4 mm size classes. Recolonisation coincided with habitat recovery, and reqeneration of the Z. capensis cover. Recolonising juveniles grew quickly, reaching adult size in three months. After that, juveniles were spawned on the mudflat by the new population. During this period the sex ratio did not return to the pre-flood 1:1, but remained female biased. Males and females grew at the same rate over the period measured, but females were consistantly larger, indicating that at some stage female growth may be faster. 9. The recolonising juveniles arrived in a regenerated habitat, at a time when temperatures were high, and conditions for growth probably optimal. If intraspecific competition was a feature of the pre-flood population it would have been elimianted in the recovery phase, by the absence of adults. 10. N. kraussianus is apparently omnivorous and proabably not food limited. However, carrion, a limited resource, may be essential for growth to reproductive maturity. Adults and juveniles may compete for this resource, and any juveniles deprived of access to carrion may be stimulated to leave the parental habitat. 11. N. kraussianus is ovoviviparous, and carries up to 5 egg cases within the uterus. Each triangular egg case contains 1 egg which hatches after approximately 3 weeks, as a free swimming veliger. Yeligers metamorphose, and settle after 4-7 days, assuming a benthic mode of life. Ovoviviparity protects the developing embryo from the rigours of environmental extremes, and ensures that embryos are not swept out to sea . Additionally, veligers have a high probability of settling in the parental habitat. 12. This reproductive strategy has been compared with other prosobranchs, and the evolutionary trends within the Prosobranchia, and particularly the Nassariidae, have been related to their dispersal potential. 13. Developmental strategy is intimately related to recolonisation potential. Ovoviviparity, and the lack of pelagic larvae, did not limit the recolonisation potential of N. kraussianus, and recolonisation was probably effected by post-larval juveniles, which may disperse from neighbouring estuaries and coastal pools, by floating in coastal and tidal currents. Post-larval juveniles have two important advantages over larvae. They are less vulnerable to physical extremes, and they have a sturdy crennellated shell which probably affords them protection from predators. 14. Examples of larval recolonisation in estuarine populations have been reviewed, and the most fundamental conclusion of this work is that recolonisation is an important, and probably widespread, adaptation to estuarine conditions in South Africa.
- Full Text:
- Date Issued: 1981
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