Identification and classification of micro-estuaries using selected abiotic and biotic characteristics along the Eastern Cape coast, South Africa
- Authors: Naidoo, Lyndle Sherae
- Date: 2017
- Subjects: Estuarine ecology -- South Africa -- Eastern Cape Estuaries -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11920 , vital:27007
- Description: Many of the larger estuaries along the South African coastline are highly degraded due to human impacts, highlighting the need to conserve pristine systems. There are approximately 100 micro-estuaries along our coastline which have not yet been identified or classified and hence their ecological functioning is unknown. The aim of this study was to identify and classify micro-estuaries along the Eastern Cape coast. Specific objectives of the study were to: 1) map the distribution of estuarine habitats in a selection of micro-estuaries and assess changes over time; 2) measure the physico-chemical characteristics of the micro-estuaries in the field; 3) investigate the distribution of vegetation, identify macrophyte species and habitat integrity and classify the micro-estuaries sampled using abiotic and botanical characteristics. A total of 30 systems were identified of which 10 were selected for sampling which took place seasonally (2015-2016). A relationship between open water surface area and short term rainfall was only evident in Cunge, Sandy Bottom and Ichabana. In the field it was observed that after heavy rainfall, open water surface area increased and mouth breaching occurred. Salinity was the only water column characteristic that showed differences; salinity increased in response to over wash events. Sand was dominant in all systems and there were no differences in sediment characteristics. A total of 8 macroalgal species, 16 estuarine macrophyte species, six freshwater species and 72 riparian plant species were found. Seed bank reserves were low in all systems despite them being vegetated. Only abiotic characteristics were used for classification using Principle Components Analysis since there were no botanical differences between systems. Micro-estuaries were larger (> 0.03 ha), had a higher salinity (oligohaline, mesohaline and polyhaline conditions) and a constant water body. Micro-outlets were smaller (< 0.03 ha), had a lower salinity (oligohaline conditions were most common) and showed periods of drying. Five micro-estuaries (Shelbertsstroom, Kwesani, Cunge, Mtwendwe and Mtendwe) and five micro-outlets (Stromatolite, Sandy Bottom, Ichabana, Palm Tree and Black Rock) were classified. This study has shown that the micro-estuaries along the Eastern Cape coast are pristine (i.e. intact riparian zone and catchment), untouched and highly dynamic systems (i.e. great variation in water surface area and mouth condition) highlighting their need for protection.
- Full Text:
- Date Issued: 2017
Influence of sedimentological and hydrological processes on the distribution of the Spartina maritima salt marsh in the Keurbooms Estuary, Western Cape
- Authors: Mfikili, Athi Nkosibonile
- Date: 2017
- Subjects: Salt marshes -- South Africa -- Western Cape Estuarine hydrology -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13004 , vital:27143
- Description: Salt marshes are some of the most productive ecosystems in the world and have been the centre of attention over the past few decades, due to their decline as a result of global climate change and anthropogenic impacts. The growth of salt marshes is determined by substrate type, soil conductivity and elevation. The permanently open Keurbooms Estuary along the south-east coast of South Africa is subjected to occasional fluvial flooding and its intertidal area lacks well developed salt marshes, with Spartina maritima restricted to the lower reaches of the Bitou tributary and a few sections of the Keurbooms tributary. Presumeably because of fine sediment habitat in the confluence and lower Bitou tributary. The salinity of the estuarine water ranges between 0.1 – 26.9 and 3.2 – 35.3 in the Bitou and Keurbooms tributaries respectively. A typical salt wedge salinity pattern is common in the Keurbooms tributary where saline water often intrudes underneath the freshwater, especially during high river flows. The following hypotheses were developed and tested in this study: The limited spatial distribution of S. maritima in the Keurbooms Estuary is due to limited availability of fine sediment habitat; and the source of the fine sediment in the estuary is the Bitou tributary rather than the Keurbooms tributary or the sea. It was further postulated that after sediment characteristics, floods are the major hydrological driver determining the distribution of S. maritima in the Keurbooms Estuary. The results of the surveys of the estuarine channel bottom sediments showed that the Keurbooms tributary was mostly characterized by the sand-size sediment fraction derived from the feldspathic and sandstone with evidence of fine sediment fractions restricted to the upper reaches at the confluence with Whiskey Creek. The Bitou was almost always composed of coarse sized sediments in the upper reaches, fine sediment deposits in the middle and lower reaches and medium sorted sand with almost no clay or calcium carbonate in the estuarine component below the confluence of the tributaries. These findings were further supported by the surface sediment deposited within the S. maritima intertidal salt marsh, which showed finer sediment deposits in the Bitou marsh compared to the Keurbooms marsh surface. Similar results were also found in the sediment cores, with the Keurbooms marsh sediment becoming finer with increasing depth whereas fine sediments reduced with depth in the Bitou marsh. The results of the sediment mineralogy indicated that the increased concentrations of clay minerals in the S. maritima surface sediments are derived from the Bokkeveld shale, siltstone and clay slate exposed above the N2 Bridge in the Keurbooms Estuary. GIS mapping shows that S. maritima has been declining over the past two decades, with rapid decreases especially evident after big flooding events. The GIS mapping also indicates that the patches of the S. maritima in the Keurbooms tributary are more exposed to big floods than the Bitou marsh. Despite showing an overall decline, S. maritima area coverage remained more consistent in the lower reaches of the Bitou tributary than in the Keurbooms tributary. Despite the larger and more persistent area cover, the S. maritima plants were shorter and less dense than the plants growing in the sandy substrate. The black/grey colouration of soil with increasing depth in the Bitou tributary was an indication of the reduced state of the soil caused by prolonged waterlogged conditions. The roots of S. maritima in both tributaries were mostly restricted to the sub-surface substrate layer (i.e. 0 – 0.25 m), although the Bitou populations showed more vegetative propagation than the Keurbooms populations. This mechanism of reproduction was also demonstrated during the transplant experiment which showed a greater number of new stem production in the fine sediment substrates compared to the sandy silt substrates. Although accretion rates were not determined in this study, the short-term sediment deposition rates revealed that sedimentation is active in the marshes of the Keurbooms Estuary. Therefore, in spite of showing a decline in area cover, the production of viable seed and observed vegetative propagation suggest that the S. maritima is likely to colonize open stable intertidal mudflats / sandflats, thus maintaining its distribution as an intertidal species in the salt marshes of the Keurbooms Estuary.
- Full Text:
- Date Issued: 2017
Integration of Eucalyptus coppice regeneration with mechanical harvesting in South Africa
- Authors: Schwegman, Kylle , Ackerman, S A
- Date: 2017
- Subjects: Eucalyptus -- Regeneration Harvesting machinery
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21131 , vital:29443
- Description: In South Africa, ca. 530 000 ha of the plantation area is planted to Eucalyptus spp. which are native to Australia. Commercially grown hardwoods account for 40.5% of the total area planted to trees, yet contribute more than 70% of the timber to the pulpwood market. This is largely attributed to the superior quality of fibre and pulping properties associated with eucalypt plantations, increases in global short-fibre pulp demands. This as well as the ability to reduce the temporary unplanted period and associated re-establishment costs when choosing to regenerate a stand through coppice management. With the unlikelihood of additional eucalypts being introduced into South Africa, and a reduction in genetic gains from 3rd-4th generation tree breading programmes, most of the eucalypts currently planted will be managed for at least one coppice rotation before replanting with improved genetic material if available. This together with the increased use of mechanised silvicultural and harvesting operations, concerns have been raised as to whether the integration of Eucalyptus coppice regeneration and mechanical harvesting in South Africa is both possible and financially viable for the forest industry to practise. The need for integration becomes more important as often mechanised systems have smaller tolerance levels when compared to manual systems. The first trial was situated in Zululand and was implemented to determine the type and severity of stump damage, coppicing potential and coppice growth over the rotation, associated with four types of harvesting and extraction systems on coppice regeneration. Results obtained from these four treatments (harvesting systems that ranged from manual to fully mechanised cut-to-length systems), found that irrespective of the harvesting system used, more damage occurred to the top than bottom half of the stump, with a significant decrease in coppice regrowth with increasing stump damage. Most damage and least coppice regrowth occurred in the extraction rows where the damage recorded could be attributed to vehicle movement, tear-outs and/or log stripping. There was no significant difference between the harvesting systems in terms of stump mortality, final stem stocking and rotation-end volume. Although this trial indicates that the harvesting systems tested had no impact on tree production the severity of damage and/or difference may have been masked by the excellent coppice potential of the species used for this trial (E. grandis x E. urophylla). Based on the results obtained in the first trial, and using five existing data sets, each data set consisted of four treatment sub-sets (4m_8m_s; 2m_8m_s; 4m_8m_BOP; 2m_8m_Or) where possible to determine the cost benefits associated with each treatment at various levels of stocking over a full rotation period. BOP (best operating practice) and Or (original stocking) refers to treatments with two stems stump-1, and s (single stem) refers to one stem stump-1. Within each of the four treatment sub-sets, treatments with three levels of stump survival were sought (60%; 80%; 100%), in order to assess financial viability of harvesting different coppice regimes (one coppice stem and two coppiced stems stump-1) using a fully mechanised cut-to-length harvesting system was tested. No differences were found between one coppice stem and two coppiced stems stump-1 in terms of financial returns (internal rate of return). Of the four treatment sub-sets (4m_8m_s; 2m_8m_s; 4m_8m_BOP; 2m_8m_Or), treatments which had two coppice stems stump-1 lead to increased harvesting cost, while coppice stumps with one stem favours mechanised harvesting and reduced harvesting costs. The final trial, which was also implemented in Zululand, tested the timing of reduction of one coppice stem stump-1 at various stump and stem densities in order to develop an appropriate coppice regime that could favour fully mechanised CTL harvesting systems. Although significant differences were detected at 23 months between the additional control (current recommendation) and the various Reduction_ht (3.5 m, 4.5 m, and 6.5 m) treatments for Dbh, Ba, and Stocking. It is likely that these differences may become less with time due to the decrease in absolute and relative differences between the various treatments with time. This thesis indicates that it is possible to successfully integrate eucalypt coppice regeneration and fully mechanised CTL harvesting. As the results obtained showed that despite the harvesting-associated damage found, no significant difference occurred between the harvesting systems tested in terms of stump mortality, stem stocking (after the final reduction) and rotation-end volume. With regards to the financial implications (using internal rates of return - IRR) associated with harvesting coppice stands of one or two stems stump-1, no clear cost-benefits were found between either of these two treatment scenarios. As those factors that contribute to increased volumes per hectare (increased stem numbers and the retention of two stems stump-1), tend to become normalised across a treatment sub-set, this results in increased harvesting costs with a reduction in the IRR. Coppice management regimes need to be investigated that favour fully mechanised CTL harvesting systems (fewer stems to harvest, but with increased volumes per stem). This includes a reduction to one stem stump-1, as opposed to the current recommendations where some stumps have two stems, such as was tested in the final trial. Although initial results were promising, rotation-end data would be needed to determine any longer term impacts from carrying out an early thinning of coppice shoots to one stem stump-1. Future research needs to be carried out to: determine the influence of mechanised harvesting and extraction for difference species of eucalypts, especially for those that do not coppice as well as the species tested in these trials (Eucalyptus grandis x Eucalyptus urophylla), develop harvesting productivity and/or volume models for coppiced stands of one and two stems stump-1 for different Eucalyptus spp., determine financial returns using specifically designed coppice management regimes which optimise the integration of both mechanical harvesting and silvicultural perations.
- Full Text:
- Date Issued: 2017
Maize stalk fibre reinforced natural rubber/tyre-tread reclaimed rubber composites
- Authors: Mente, Pumza
- Date: 2017
- Subjects: Polymeric composites Rubber
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19332 , vital:28852
- Description: This research project focuses on the production of reclaimed rubber composites reinforced with natural fibres obtained from agricultural waste. The prepared natural fibre composites were characterized through evaluation of curing characteristics, tensile properties, thermal properties, dynamic mechanical properties and electron microscopy imaging. Untreated composites generally showed poor properties which were attributed to poor compatibility and fibre agglomeration. Various treatments were then employed in attempts to improve the composite properties. Fibre treatments used were water treatment and silane treatments using two different silane coupling agents. Torque, reaction rate and tensile modulus were observed to increase with addition of reclaimed rubber and natural fibres. Tensile strength and elongation at break increased with addition of natural rubber. An increase in thermal stability was observed with addition of reclaimed rubber. Dynamic mechanical analysis (DMA) results have shown that addition of reclaimed rubber resulted to an increase in glass transition temperature. Scanning electron microscopy (SEM) images of tensile fractured composites showed evidence of fibre pull-outs from the matrix. Removal of lignin from treated natural fibres was evident from thermogravimetric analysis (TGA) for all fibre treatments. There were no noticeable improvements in composites properties with use of fibre treatments and there were no statistical differences observed among the different fibre treatments. Generally, the composites prepared showed high stiffness and low tensile strength.
- Full Text:
- Date Issued: 2017
Microstructure and properties of zirconium silicide surface layers on zirlo for improved nuclear fuel cladding
- Authors: Ngongo, Sinoyolo
- Date: 2017
- Subjects: Zirconium alloys Zirconium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/20098 , vital:29107
- Description: Zirconium alloys have important applications as nuclear reactor fuel cladding material. In this study the microstructure and properties of zirconium silicide synthesized by heating ZIRLO (which is an alloy of zirconium and niobium) in contact with silicon powder has been investigated. The silicide acts as a coating layer to protect the ZIRLO from oxidation which is associated with hydrogen pick-up. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the morphology and crystal structure of the silicides respectively. Heating of ZIRLO with silicon powder was carried out in a Webb 89 Vacuum Furnace for various temperatures (1000–1400 °C) and times (4–8 hours) in an argon atmosphere or under vacuum, which resulted in the diffusion of silicon into the ZIRLO and the formation of zirconium silicide layers. The sample heat treated for 8 hours at 1000 °C did not show any evidence of inter-diffusion between the ZIRLO and silicon, this suggests that a temperature of 1000 °C is not sufficient to facilitate the formation of a silicide layer. The formation of the silicide layer was however observed after heat treatments at 1200 °C and 1400 °C using SEM and TEM. The silicide formed at 1200 °C as a layer on the ZIRLO sample and voids were observed in this layer, most likely due to the Kirkendall effect which occurs in solid state diffusion. The results suggest that Zr has a larger flux than Si as the voids formed in the ZIRLO. The temperature of 1400 °C appears to exceed the ideal required for silicide formation on the surface of ZIRLO, since the silicon infiltrated very far into the ZIRLO and in fact reacted with the entire ZIRLO sample. Both these samples were heat treated for 8 hours in an argon atmosphere. Silicide layers without voids were obtained in the case where ZIRLO and Si were heat treated for 8 and 4 hours at 1200 °C in an argon atmosphere and under vacuum respectively. The average penetration rate, calculated from the aforementioned heat treatments, of Si into Zr was calculated to be 4.5 μm/hour. The diffusion coefficient of Si in Zr was also estimated and it differs by about a factor of 104 from the reported value Zr into Si diffusion coefficient.
- Full Text:
- Date Issued: 2017
Optical fibre measurement for clock tones in telescope networks
- Authors: Dlamini, Phumla Patience
- Date: 2017
- Subjects: Fiber optics Very large array telescopes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22200 , vital:29872
- Description: Astronomy dates back to the early man’s impression of the heavens with little information recorded including some drawings of comets, eclipse and supernovas[1]. Major progress has been made in the field of Astronomy since then. Scientific curiosity to probe the universe in attempt to answer questions such as the origin of the universe, the matter it is made of, the formation of stars, planets and galaxies, and tracking life in other solar systems has brought about the need for more advanced tools capable of detailed observations. In 1608 H. Lippershey developed the first refracting telescope[2], [3]. A year later Galileo used a similar telescope pointing skywards discovering mountains and craters on the earth’s moon, the moons of Jupiter and the phases of Venus. Over the years telescopes have been developed with advancements from the optical telescope towards much larger and more sensitive radio telescopes. The first radio signal from space was detected by Karl Jansky and ever since then astronomers have been using radio telescopes to explore the universe by detecting radio waves emitted by cosmic objects[4]. The ability of radio telescopes to detect weak signals is related to the signal capture surface. As the demand for sensitivity, transmission bandwidth and data rate increases, so does the need for telescopes with a large field of view and capability to observe different parts of the sky at once[5]. This is possible with radio telescope array, with the data from the antennas combined electronically to produce a high resolution image of the sky. The South African MeerKAT radio telescope is an array of 64 interlinked antennas each transmitting up to 160 Gbps of data to the central processing site over optical fibre which is ideal for carrying large volumes of data at high speeds. The MeerKAT telescope is a precursor to the Square kilometer Array which will have up to 50 times the sensitivity and 10000 times the survey speed than the best telescope[6].
- Full Text:
- Date Issued: 2017
Optimal cycle dating of large financial time series
- Authors: Kapp, Konrad Phillip
- Date: 2017
- Subjects: Computer algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/17767 , vital:28452
- Description: The study of cycles in the context of economic time series has been active for many decades, if not centuries; however, it was only in recent decades that more formal approaches for identifying cycles have been developed. Litvine and Bismans (2015) proposed a new approach for dating cycles in financial time series, for purposes of optimising buysell strategies. In this approach, cycle dating is presented as an optimisation problem. They also introduced a method for optimising this problem, known as the hierarchical method (using full evaluation 2, or HR-FE2). However, this method may be impractical for large data sets as it may require unacceptably long computation time. In this study, new procedures that date cycles using the approach proposed by Litvine and Bismans (2015), were introduced, and were speciffically developed to be feasible for large time series data sets. These procedures are the stochastic generation and adaptation (SGA), buy-sell adapted Extrema importance identity sequence retrieval (BSA-EIISR) and buysell adapted bottom-up (BSA-BU) methods. An existing optimisation technique, known as particle swarm optimisation (PSO), was also employed. A statistical comparison was then made between these methods, including HR-FE2. This involved evaluating, on simulated data, the performance of the algorithms in terms of objective function value and computation time on different time series lengths, Hurst exponent, and number of buy-sell points. The SRace methodology (T. Zhang, Georgiopoulos, and Anagnostopoulos 2013) was then applied to these results in order to determine the most effcient methods. It was determined that, statistically, SGA, BSA-EIISR and BSA-BU are the most effcient methods. Number of buysell points was found to have the largest effect on relative performance of these methods. In some cases, the Hurst exponent also has a small effect on relative performance.
- Full Text:
- Date Issued: 2017
Optimising syzygium cordatum dye extraction and subsequent cotton dyeing incorporating organic electrolytes
- Authors: Gamedze, Nombuso Faith
- Date: 2017
- Subjects: Dyes and dyeing -- Cotton Syzygium cordatum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19509 , vital:28888
- Description: The present investigation was carried out to optimize the extraction of natural dye from Syzygium cordatum,bark trees and then to evaluate its use in the dyeing of cotton fabric incorporating organic electrolyte. The bark was collected from recently fallen trees and twigs pruned from old trees, since they have greater dye content than the younger trees, dried for two weeks, crushed with a hammer and ground into powder. Grinding of bark was done to ensure a uniform particle size with a large surface area to facilitate quick extraction. The relevant conditions for natural dye extraction using a methanol/water mixture were optimized by Response Surface Methodology (RSM), with the help of Design Expert Version 7.0. The central composite design (CCD) was applied to design experiments for the evaluation of the interactive effects of the three most important operating extracting variables namely, temperature, time and liquor volume on 25g bark powder. This approach decreased the required number of experiments, and the following optimized extraction conditions were derived; temperature 700C, time 51minutes and material-to-liquor ratio 1:16. Dye used for subsequent dyeing was extracted using the optimized conditions. To determine the best conditions for dyeing cotton fabric with the dye extract, dyeing was carried out in a rotating canister machine, using two different organic electrolytes, namely trisodium nitrilo triacetate (trisodium NTA) and dimethylformamide, as mordants. The use of organic electrolytes, as mordants, was to ensure eco-friendliness of the dyeing, and with a maximum concentration of 3g/L being used to reduce the effluent load. Three different mordanting techniques, namely simultaneous, pre-mordanting and post-mordanting were investigated so as to establish which is best. The impact of the two organic electrolyte mordants on certain physical properties of the cotton fabric was also determined. The dyeing of cotton with theSyzygium cordatum bark dye extract, in conjuction with an organic electrolyte, generally showed good results, with trisodium NTA superior to dimethylformamide as a mordant. An increase in trisodium NTA mordant concentration increased dye exhaustion and a dye exhaustion of 23.7% being achieved with 3g/L pre-mordanting. This is still relatively low, however, and the use of an exhausting agent needs to be explored. The fabric dyed with a mordant, exhibited good wash, rub and perspiration fastness, with trisodium NTA superior to dimethylformamide. The use of trisodium NTA increased the strength of the dyed fabric whereas the use of dimethylformamide decreased it. In general, pre- and simultaneous mordants were better than post-mordanting. It has been shown that the dyeing of cotton, using Syzygium cordatum bark dye extract, in conjuction with an organic electrolyte, particulary trisodium NTA, has potential and can be recommended for craft applications. Optimised conditions for dye extraction and cotton dyeing have been derived and which can be recommended for use by crafters in Swaziland.
- Full Text:
- Date Issued: 2017
Performance and throughput rates of quantity surveying students: a cohort analysis
- Authors: Dent, Sharon Peta
- Date: 2017
- Subjects: Cohort analysis Quantity surveying
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/17581 , vital:28382
- Description: Performance and throughput rates at South African tertiary institutions are low, especially within the science, engineering and technology fields of study. The causes of this poor performance and throughput are difficult to predict, and incorrect assumptions are often made on which students are most likely to fail. The need to investigate this issue is vital in South Africa, where the contributing factors to poor performance and throughput are exacerbated by recent political and economic disparities in the diverse population. In order to better understand the issue within the built environment sector, this study evaluated the performance and throughput rates of fifteen first-year cohorts within the Department of Quantity Surveying at the Nelson Mandela Metropolitan University. The main aim of this study was to investigate the changes in the student population within the department, and to develop a framework for the future prediction of a student’s likelihood of success or failure. In order to achieve this objective, a retrospective longitudinal approach, i.e. a cohort study, was adopted. The study plotted the trends in performance and throughput rates over a period of time; it measured the strength of the relationships between several variables and performance and throughput; and it culminated in the establishment of predictors of performance and throughput rates. Ultimately, the prediction variables could be utilised in the development of influence diagrams as prediction frameworks. The research revealed that the performance and throughput rates of students in the department are improving. This highlights the importance of undertaking a narrow, departmental level analysis; as the findings in this smaller sphere do not match the general theory and assumptions covered in the literature.
- Full Text:
- Date Issued: 2017
Population status and habitat use of Indian Ocean humpback dolphins (sousa plumbea) along the south coast of South Africa
- Authors: Conry, Danielle Shanè
- Date: 2017
- Subjects: Sousa -- Population viability analysis -- South Africa Sousa -- Habitat -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15556 , vital:28269
- Description: Long-lived, top-level predators, such as some marine mammals, serve as important indicators of ecosystem health. Assessing the abundance and habitat use of such marine top predators is essential for the formulation of effective conservation and management actions. There is considerable concern over the viability of small humpback dolphin opulations across a global scale and a number of studies have raised concerns over their vulnerability to extinction. In light of the recent uplisting of Indian Ocean humpback dolphins (Sousa plumbea) to ‘Endangered’ on the South African Red Data list, there is an urgent need for a greater understanding of the abundance and spatial distribution of this species along the South African coastline. Using small vessels as survey platforms between March 2014 and June 2015, this study attempted to determine the abundance, spatial distribution and habitat preferences of Indian Ocean humpback dolphins along 150 km of South Africa’s south coast. A further aim was to assess the utilisation of the current Marine Protected Area network by humpback dolphins along this coastline relative to areas outside of formal protection. Mark-recapture methods applied to photo-identification data produced abundance estimates of 84 individuals (95% CI: 72-115) within the study area for both open and closed models. An average group size of 3.94 individuals (range 1-12; SD = ± 2.82) was observed during the study, indicating a decrease in average group size of ~45 % from a previous assessment in 2002/03. Such a decline in group size could potentially be a result of a change in social structure in response to reduced prey availability. Spatial analyses of humpback dolphin geographic positions, using a kernel density estimator (KDE) and effort-weighted density grid analyses, indicate that the species is unevenly distributed over the coastal zone within the area. Sightings occurred at the highest densities within Buffels Bay and along Goukamma MPA, followed by Plettenberg Bay, Nature’s Valley, and around the Bloukrans, Elandsbos and Groot River East mouths. Habitat preference was assessed using a standard classification-based method and the results indicate a strong preference, in particular, for Dissipative Intermediate Sandy Coast habitat, followed by Very Exposed Rocky Coast, Intermediate Sandy Coast, Estuarine Shore, Mixed Shore and Inshore Reef habitats. Areas of high humpback dolphin densities appear to be associated with these habitat types, especially with Dissipative-Intermediate Sandy Coast habitat. Humpback dolphins were sighted at relatively low densities along stretches of coastline consisting predominately of Exposed Rocky Shore habitat. Long expanses of this habitat type may limit humpback dolphin movements along the coast. The observed patterns in distribution and habitat preferences may be linked to the availability of prey and/or the avoidance of predators. Average sightings per kilometer travelled (SPUE) indicate that the utilisation of the Robberg and Tsitsikamma MPAs by humpback dolphins was low, most likely due to the low availability of sandy coastline in these areas. In contrast, the utilisation of the Goukamma MPA, which is characterised by a high availability of Dissipative-Intermediate Sandy Coast, was very high. The low population numbers and declines in average group size of Indian Ocean humpback dolphins within the study area warrant concern and call for effective conservation and management measures. In light of ever-increasing levels of anthropogenic threats to coastal areas, future research and long-term monitoring of the population is essential to broaden our knowledge of the species and to detect population trends.
- Full Text:
- Date Issued: 2017
Property development in Mthatha: an interactive framework
- Authors: Bavu, Sonwabile
- Date: 2017
- Subjects: Real estate development -- South Africa -- Eastern Cape Land use -- South Africa -- Eastern Cape , Sustainable development -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14553 , vital:27761
- Description: Property development (PD) is basically driven by the need or demand from the people. Sustainable property development has emerged in response to a global problem – and the need to maintain environmental integrity, according to Gurry (2011) cited by Botha (2013: 7). Keeping and Shiers (2004) state that property development, as a whole, has to balance social, economic and environmental needs. Emanating from the above, any successful development project must offer investors security, infrastructure and efficiency and should also put the needs of citizens at the forefront of all its planning activities. Availability of land, existing infrastructure, availability of finance, economic conditions, political influence and corruption always influence growth of property development in any area. This study aims to identify factors that contribute to lack of property development in Mthatha. Data collected shows that the challenges sometimes lead to failure and delays of the development. The purpose of this study is to identify these challenges, investigate the available literature, consider what has been done so far to address these challenges and make recommendations. It is essential to understand the state of the town and perceptions of the people in the area dealing with Property Development. Mthatha is the main focus of the study because of the perceived number of failed and delayed property development initiatives. The primary and secondary data collected provide the basis for understanding challenges that lead to such failures and delays. This research was conducted by means of a review of the related literature and an empirical study. The empirical study was conducted using a quantitative statistical approach by distributing research questionnaires to members falling within the sample population. The primary objective of the study is to develop a framework for successful implementation of property developments in Mthatha. The study’s findings reveal shortcomings which contribute to the study’s identified problems relating to property development in Mthatha, namely: decaying infrastructure, shortage of land, implementation of the IDP, availability of finance to promote real estate developments, political influence and corruption. Wikipedia defines Property Development as a “multifaceted business encompassing activities that range from the renovations and release of existing buildings to the purchase of land and the sale of improved land or parcels to others”. Harvey and Jowsey (2004), as cited by Botha (2013: 5), define Property Development as a process that involves changing or intensifying the use of land to produce buildings for occupation.
- Full Text:
- Date Issued: 2017
Quality management systems – a fundamental business imperative for construction companies: a case study of Bay West city mall
- Authors: Mthi, Vuyolwethu Feza Philisa
- Date: 2017
- Subjects: Construction projects -- Management Construction industry -- Management , Total quality management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45908 , vital:39319
- Description: The quality of construction projects in South Africa has long been below par which is evident in the reports of poor project performance, poorly implemented construction processes, or even worse projects delivered at an unexpected cost to the client. Private and public sector clients are dissatisfied with the quality of work produced by contractors whilst the rectification of substandard construction work on many of the low-cost housing projects throughout South Africa has left the state with a bill of around R50 billion. As a result this research suggests that company’s implement quality management systems as a means to differentiate and elevate themselves above current industry performance. The research inquiry was conducted through the use of a case study (Bay West City Mall). Data was collected primarily through participant observation and survey questionnaires with the various participants on the Bay West City Mall project. The collected data were extracted, errors eliminated/accounted for, coded and entered onto an excel spreadsheet for easy reference and analysis. For the interpretation of the data the researcher used the bivariate tabulation method where categorical data is measured using ordinal and nominal scales. The study concluded that the employment of quality management systems should no longer be seen as optional but as fundamental to the continual improvement of construction companies, those organizations that fully institutionalise the principles of quality management will have a strong chance of improving their project performance, reducing project costs, getting repeat business and increasing profits on projects. It is the recommendation of this study that more research be conducted into how quality management, in the construction industry, can assist in alleviating other problems that plague the South African construction industry such as poor performance relating to health & safety, cost, time, low profit margins and poor cultural practices.
- Full Text:
- Date Issued: 2017
Resource partitioning in the world’s largest gannetry
- Authors: Botha, Jonathan Aubrey
- Date: 2017
- Subjects: Gannets -- South Africa Birds of prey -- Behavior -- South Africa , Birds -- Behavior
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/14707 , vital:27828
- Description: Understanding strategies of resource partitioning within populations is a fundamental aspect of the study of ecology, and one which has been well documented across various taxa. In seabirds, sex-specific differences in foraging behaviour are often thought to reflect strategies of resource partitioning to avoid intra-specific competition. At present Bird Island in Algoa Bay hosts the world’s largest breeding population of gannets, with recent population estimates numbering well over 90 000 breeding pairs. Given the large size of this colony, intense levels of intra-specific competition are expected during the breeding season, particularly in years of poor feeding conditions. In addition, continuous foraging around the breeding colony may lead to the local depletion of prey as the season progresses, calling for flexibility in the foraging behaviour and diet of breeding individuals. Therefore, the aim of this dissertation was to investigate resource partitioning in Cape gannets breeding at Bird Island through strategies of sex-specific foraging and intra-seasonal variability in foraging behaviour and diet. To achieve this, the spatial and temporal aspects of Cape gannet foraging behaviour were assessed during the early stages of chick rearing, over two consecutive breeding seasons (2011/12, 2012/13) using GPS tracking and VHF monitoring. In addition, intra-seasonal variability in foraging behaviour and diet were investigated, taking into account the influence of sex and chick age, to provide a comprehensive assessment of foraging behaviour throughout the chick rearing period. GPS tracking data for 79 birds revealed limited evidence for sex-specific differences over spatial dimensions. An extension in the foraging range of females during a year of lower prey availability (2012/13) was, however, evident. This suggests a possible sex-specific response to prey limitation, likely reflecting resource partitioning strategies or differences in nutritional requirements. VHF data for 95 additional birds revealed a clear pattern in temporal foraging behaviour. In general, females were more likely to be on a foraging trip during the early and mid-day hours, with the probability of males being on a foraging trip increasing towards the late afternoon. Continuous tracking of individuals throughout the 2015/16 breeding season further revealed little evidence for sex-specific differences in spatial distribution and forging effort during both the guard and post-guard stages of chick rearing. A clear increase in foraging range was evident during the early stages of chick rearing as the season progressed. However, birds attending chicks older than 50 days showed an unexpected contraction in foraging range, which appeared to coincide with a dietary shift. During the early stages of breeding the diet was comprised almost exclusively of anchovy, the proportion of which decreased progressively in the diet throughout the breeding season. This was mirrored by a substantial increase in the proportion of saury in the diet. These results suggest that Cape gannets increase their foraging range in response to local prey depletion as the breeding season progresses. However, when alternative prey becomes available they may shift their diet, allowing them to access prey closer to the breeding colony. Overall, this dissertation provides insight into sex-specific behaviour in a monomorphic seabird, suggesting a marginal degree of spatial segregation. The results provide the first support for sex-related temporal foraging segregation in gannets. Such separation could potentially be driven by resource partitioning, but could also relate to differential nutritional requirements. In addition, this study also provided the first comprehensive assessment of foraging behaviour throughout the guard and post guard stages of chick rearing in gannets. These results suggest that a combination of foraging and dietary flexibility may allow Cape gannets to buffer the effects of prey depletion during the breeding season. In conclusion, resource partitioning through sex-specific foraging appears to be limited in the Cape gannet population at Bird Island. Segregation via alternative pathways may however be possible and as such, future studies should consider the influence of individual level segregation and habitat specialization.
- Full Text:
- Date Issued: 2017
Seasonal physiological and behavioural responses of a small bird in a hot, arid habitat
- Authors: Pattinson, Nicholas Bruce
- Date: 2017
- Subjects: Birds -- Behavior Birds -- Physiology , Birds -- Ecophysiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19728 , vital:28948
- Description: The role that climate plays in the ecology of organisms is perhaps the most pronounced where the earth’s environments are most extreme. In arid-zones, organisms have to deal with large seasonal shifts and/or extremes in temperature and/or moisture levels. As a result, arid-zone species are sensitive to climatic changes. I assessed the physiological and behavioural adjustments of an arid-zone endemic passerine, the rufous-eared warbler (Malcorus pectoralis), to seasonal changes in the Karoo semi-desert of South Africa. Respirometry measurements in the field showed that the warblers’ basal metabolic rate was lower and set point body temperature (Tb) was higher in summer compared to winter. At high air temperatures (Ta) evaporative water loss (EWL) rate was significantly lower in summer compared to winter, while Tb showed a clear pattern of heterothermy that was similar in both seasons. Compared to winter, the warblers in summer were able to remain calm, and tolerate higher Ta’s, before their Tb’s increased to potentially detrimental levels. Behavioural observations showed that free-living warblers exhibited significant temperature-dependence in their behaviour; they increased panting behaviour, and reduced activity levels, time spent preening, and foraging effort at high Ta’s in summer. The warblers also displayed a considerable decrease in foraging success, and a shift in microsite use, at high Ta’s in summer. I hypothesise that the flexible responses the rufous-eared warblers show are aimed at increasing their heat tolerance in summer, and help them balance their energy and water demands in an arid environment that exhibits wide seasonality in Ta, in addition to high summer Ta. My findings emphasise the importance of identifying, as well as understanding, the associated costs of physiological and behavioural responses to environmental variables. This information is valuable in terms of predicting biologically meaningful responses (and hence, vulnerability) of arid-zone avian communities to climactic shifts.
- Full Text:
- Date Issued: 2017
Seed ecology and growth comparisons of native (Virgilia divaricata) and invasive alien (Acacia mearnsii and A. melanoxylon) plants: implications for conservation
- Authors: Goets, Stefan Albert
- Date: 2017
- Subjects: Seeds -- Ecology Plants -- Reproduction , Vegetation dynamics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15248 , vital:28191
- Description: The abundance of invasive alien plants, with their numerous associated negative effects, has resulted in challenging and costly management requirements in South Africa. Management of invasives is further complicated when species have rapid inherent growth rates, atmospheric nitrogen fixing capabilities and large, persistent seed banks. Management strategies other than the usual mechanical, chemical, and biological (and combinations thereof) methods may be more effective. An alternative strategy is ’habitat management’, whereby management may be aimed at favouring native species. If the native species could compete favourably with, and possibly exclude, the invasive species, which is more likely when the species are ecologically similar, management may be more effective. This study investigated the competitive performance of two invasive species, Acacia mearnsii De Wild. and Acacia melanoxylon R.Br., and an indigenous ecological analogue, Virgilia divaricata Adamson, on the southern Cape Coast of South Africa. Both acacias are included among the five worst invasive species in the native forest and fynbos shrubland ecosystems. Performance was compared among the three species in terms of germination success (responses to five stimuli, namely chipping, hot water exposure, dry heat pulse, smoke, and control, incubated at 12 or 20°C), soil-stored seed bank densities and viability at different soil depths, and individual growth performance in seedling and sapling stages (and the effect of inter-specific competition on the latter). Virgilia divaricata performed comparably to the acacias in most aspects. Responses to germination stimuli at both temperature regimes were comparable among species, with chipping and hot water exposure resulting in the highest germination success. Acacia melanoxylon displayed poorer germination response under the cool temperature regime than the warm regime. Of the three species, A. mearnsii (7 596 seeds m-2) had the highest seed bank density, followed by V. divaricata (938 seeds m-2) and A. melanoxylon (274 seeds m-2). Seed viability was high (87-91%) in all three species. Neither seed density nor seed viability differed significantly between soil depths, and there were no clear differences in this aspect between species. In terms of growth during the seedling stage, V. divaricata outperformed A. mearnsii. In the sapling stage, growth was comparable between the three species and was not affected by the extent of competition from neighbouring saplings. Overall, the findings of this study suggest that the success of A. mearnsii as an invader is primarily attributable to its large seed banks. However, the good performance of V. divaricata seedlings and no apparent negative effect of competition on sapling growth from A. mearnsii and A. melanoxylon suggest that it may be used in the management of the acacias along with other management strategies. Due to the similarity observed between the three species, any management operation (such as fire) that would benefit V. divaricata recruitment would benefit the acacias equally (except for potentially reduced germination of A. melanoxylon in cooler seasons). Management should thus attempt to prevent the germination of Acacia seeds. Alternatively, dense localised Acacia seed banks may be reduced by repeat burning. On a small scale, areas where V. divaricata would occur naturally (or which are completely compromised ecologically) can be seeded with pre-treated (chipped or hot water exposure) V. divaricata seeds. If V. divaricata is given enough time to establish dense stands, subsequent germination and growth of the acacias should be suppressed and simultaneously promote forest re-establishment. To further decrease Acacia success, biocontrol (seed-boring weevils, flower-galling midges, and rust fungus) should be widely disseminated.
- Full Text:
- Date Issued: 2017
Statistical methods for the detection of non-technical losses: a case study for the Nelson Mandela Bay Municipality
- Authors: Pazi, Sisa
- Date: 2017
- Subjects: Nonparametric statistics Mathematical statistics , Statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/19706 , vital:28939
- Description: Electricity is one of the most stolen commodities in the world. Electricity theft can be defined as the criminal act of stealing electrical power. Several types of electricity theft exist, including illegal connections and bypassing and tampering with energy meters. The negative financial impacts, due to lost revenue, of electricity theft are far reaching and affect both developing and developed countries. . Here in South Africa, Eskom loses over R2 Billion annually due to electricity theft. Data mining and nonparametric statistical methods have been used to detect fraudulent usage of electricity by assessing abnormalities and abrupt changes in kilowatt hour (kWh) consumption patterns. Identifying effective measures to detect fraudulent electricity usage is an active area of research in the electrical domain. In this study, Support Vector Machines (SVM), Naïve Bayes (NB) and k-Nearest Neighbour (KNN) algorithms were used to design and propose an electricity fraud detection model. Using the Nelson Mandela Bay Municipality as a case study, three classifiers were built with SVM, NB and KNN algorithms. The performance of these classifiers were evaluated and compared.
- Full Text:
- Date Issued: 2017
Statistical modelling applied to perceptions of fraud
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics , Mathematical models Bank fraud Banks and banking -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41073 , vital:36289
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
Statistical modelling applied to perceptions of fraud
- Authors: Mnci, Mihlali
- Date: 2017
- Subjects: Mathematical statistics Statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41064 , vital:36288
- Description: This study aims to investigate and identify attitudes, behaviours and perceptions harboured by bank cardholders and merchants, which are associated with a higher susceptibility towards experiencing bank card fraud. Primary data was obtained from bank cardholders and merchants, from various business categories, in both the Nelson Mandela Bay Metropolitan Municipality and the City of Johannesburg Metropolitan Municipality. Following the use of parametric Multinomial Logistic Regression (MLR) and nonparametric conditional density estimation to analyse the data, the results are compared and relevant covariates/perceptions are determined from the more accurate of the two techniques. The results of the analysed survey data serve as a tool, highlighting areas which require further education and awareness on the part of merchants and bank clients.
- Full Text:
- Date Issued: 2017
Synthesis of L-menthyl glyoxylate, an important intermediate in the manufacture of ARVS, using flow chemistry technology
- Authors: Moyo, McQuillan
- Date: 2017
- Subjects: Chemistry , Pharmaceutical chemistry , Organic compounds -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12019 , vital:27018
- Description: Herein an alternative approach to the conventional batch synthesis of L-menthyl glyoxylate hydrate (MGH), an important intermediate in the synthesis of drugs of importance is reported, through flow chemistry technology. MGH was initially synthesized in batch and various reaction parameters optimized. It was found to proceed to completion after 6 hours of esterifying glyoxylic acid with excess alcohol (L-menthol) in the presence of a catalyst, ideally amberlyst-15 (an ion exchange resin) at 105 °C giving a yield of 72 %. The batch reaction conditions were adopted in a continuous flow synthesis setup, using the Labtrix Start system, in which reaction conditions were optimized. The optimization of glyoxylic acid conversion (92 %) in the Labtrix Start system gave reaction conditions that resulted in low MGH selectivity (25 %) whereas the optimization for MGH selectivity (100 %) gave a conversion a poor glyoxylic acid conversion (15 %). The FlowSyn system fitted with a column reactor gave the best results, in which the optimum conditions were an excess of L-menthol (1.5 M, 6.0 equiv.), temperature (80 °C) and a residence time of 2.5 minutes with a high selectivity (77 %) and average conversion (50 %). The optimized reaction conditions for conversion and selectivity on the different flow systems did not vary significantly and similar trends were observed for the systems. It was shown that an increase in temperature, mole equivalents and residence time led to an increase in MGH conversion in all flow systems. The scale up of the esterification reaction from the Labtrix Start system (19 μL microreactor) to the FlowSyn system fitted with a 2 mL reactor chip, showed that the reaction proceeds with a slight drop in selectivity from 100 % to 92 % while conversion dropped from 15 to 12 %. On the contrary, a significant drop in conversion and selectivity were observed when the FlowSyn column reactor was up-scaled to the Elite-tubular furnace, owing to the poor mixing in the larger channel size reactor.
- Full Text:
- Date Issued: 2017
Synthesis, crystal structures and molecular modelling of rare earth complexes with bis(2-pyridylmethyl)amine: aim topological analysis and ligand conformation search
- Authors: Matthews, Cameron
- Date: 2017
- Subjects: Rare earths , Ligands , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/8230 , vital:26229
- Description: Eight rare earth complexes with bis(2-pyridylmethyl)amine (DPA) were synthesised and recrystallised, under air-sensitive or low moisture conditions. The crystal structures were successfully determined, via SC-XRD, and the asymmetric units of five complexes (1, 3, 5, 6 and 7) were submitted for DFT molecular modelling calculations, which involved geometry optimisation and frequency calculations. The neutral complexes obtained were bis(bis(2-pyridylmethyl)amine)-trichloro-lanthanum(III) [LaCl3(DPA)2] (1), bis(bis(2-pyridylmethyl)amine)-trichloro-cerium(III)) [CeCl3(DPA)2] (2), bis(μ2-chloro)-diaqua-tetrachloro-bis(bis(2-pyridylmethyl)amine)-di-praseodymium(III) [PrCl2(μ-Cl)(DPA)(OH2)]2 (3) and bis(μ2-methoxo)-bis(bis(2-pyridylmethyl)amine)- tetrachloro-di-dysprosium(III) [DyCl2(μ-OCH3)(DPA)]2 (4). The cationic complexes obtained in this study were dichloro-bis(bis(2-pyridylmethyl)amine)- neodymium(III) chloride methanol solvate [NdCl2(DPA)2]Cl·CH3OH (5), dichloro-bis(bis(2- pyridylmethyl)amine)-dysprosium(III) chloride methanol solvate [DyCl2(DPA)2]Cl·CH3OH (6), dichloro-bis(bis(2-pyridylmethyl)amine)-yttrium(III) chloride methanol solvate [YCl2(DPA)2]Cl·CH3OH (7) and dichloro-bis(bis(2-pyridylmethyl)amine)-lutetium(III) chloride methanol solvate [LuCl2(DPA)2]Cl·CH3OH (8). The ‘Quantum theory of atoms in molecules’ approach was used to investigate the electron density topology, primarily in order to investigate the hydrogen and coordination bonds for three of the eight complexes. Two of the neutral complexes contain the ‘early’ rare earth elements lanthanum and praseodymium and one cationic complex contains the ‘late’ lanthanide element dysprosium. Noncovalent interaction analysis was also performed on the aforementioned complexes in order to gain a deeper understanding of the intra-molecular stereo-electronic interactions. Spin density analysis was used to investigate the distribution of unpaired electron density at and around the metal centres of the aforementioned paramagnetic Pr- and Dy-complexes. A ligand conformation search for DPA was undertaken and 32 low energy conformers were identified and their relative energies were determined using two DFT functionals, namely M06 and M06-2X.
- Full Text:
- Date Issued: 2017