Bacterial degradation of fossil fuel waste in aqueous and solid media
- Authors: Edeki, Oghenekume Gerald
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54565 , vital:26588
- Description: The generation of environmental pollutants worldwide is mainly due to over reliance on fossil fuels as a source of energy. As a result of the negative impacts of these pollutants on the health of humans, animals, plants and microorganisms, global attention has been directed towards ways of containing this problem. Biodegradation of fossil fuel is one of the most effective methods used to remediate contaminated systems. However with regard to coal waste, much of what is known is based on the ability of fungal species to biosolubilize this material under enrichment conditions in a laboratory setting. For effective biodegradation as a remediation technique, there is an immediate need to source, isolate, enrich and incorporate other microorganisms such as bacteria into bioremediation technologies. The goal of this dissertation was to isolate bacteria from fossil fuel contaminated environments and to demonstrate competence for petroleum hydrocarbon degradation which was achieved using a combination of analytical methods such as spectrophotometry, FT-IR, SEM and GC-MS. Screening for biodegradation of coal and petroleum hydrocarbon waste resulted in the isolation of 75 bacterial strains of which 15 showed good potential for use in developing remedial biotechnologies. Spectrophotometric analysis of bacteria both in coal and petroleum hydrocarbons (all in aqueous media) revealed a high proliferation of bacteria in these media suggesting that these microbes can effectively utilize the various substrates as a source of carbon. The isolated bacteria effectively degraded and converted waste coal to humic and fulvic acids; products required to enrich coal mine dumps to support re-vegetation. Scanning electron microscopy showed the attachment of bacteria to waste coal surfaces and the disintegration of coal structures while FT-IR analysis of extracted humic-like substances from biodegraded waste coal revealed these to have the same functional groups as commercial humic acid. Specific consortia which were established using the isolated bacterial strains, showed greater potential to biodegrade coal than did individual isolates. This was evident in experiments carried out on coal and hydrocarbons where the efficient colonization and utilization of these substrates by each bacterial consortium was observed due to the effect of added nutrients such as algae. The biodegradation of liquid petroleum hydrocarbons (diesel and BTEX) was also achieved using the 15 bacterial isolates. GC-MS analysis of extracted residual PHC from aqueous and solid media revealed rapid breakdown of these contaminants by bacteria. Different bacterial consortia established from the individual isolates were shown to be more efficient than single isolates indicating that formulated consortia are the biocatalysts of choice for fossil fuel biodegradation. This study represents one of the most detailed screenings for bacteria from fossil fuel contaminated sites and the isolation of strains with potential to biodegrade coal and petroleum hydrocarbon wastes. Several consortia have been developed and these show potential for further development as biocatalysts for use in bioremediation technology development. An evaluation of efficiency of each established bacterial consortium for biodegradation in a commercial and/or industrial setting at pilot scale is now needed.
- Full Text:
- Date Issued: 2015
Coastal pH variability and the eco-physiological and behavioural response of a coastal fish species in light of future ocean acidification
- Authors: Edworthy, Carla
- Date: 2021
- Subjects: Ocean acidification , Diplodus capensis (Blacktail) , Diplodus -- South Africa -- Algoa Bay , Diplodus -- Metabolism , Diplodus -- Food , Diplodus -- Larvae , Marine ecology -- South Africa -- Algoa Bay , Carbon dioxide -- Physiological effect , Respiration -- Measurement
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/176793 , vital:42759 , 10.21504/10962/176793
- Description: Ocean acidification (OA) is a global phenomenon referring to a decrease in ocean pH and a perturbation of the seawater carbonate system due to ever-increasing atmospheric CO2 concentrations. In coastal environments, identifying the impacts of OA is complex due to the multiple contributors to pH variability by coastal processes, such as freshwater inflow, upwelling, hydrodynamic processes, and biological activity. The aim of this PhD study was to quantify the local processes occurring in a temperate coastal embayment, Algoa Bay in South Africa, that contribute to pH and carbonate chemistry variability over time (monthly and 24-hour) and space (~10 km) and examine how this variability impacts a local fish species, Diplodus capensis, also commonly known as ‘blacktail’. Algoa Bay, known for its complex oceanography, is an interesting location in which to quantify carbonate chemistry variability. To assess this variability, monitoring sites were selected to coincide with the Algoa Bay Sentinel Site long-term ecological research (LTER) and continuous monitoring (CMP) programmes. The average pH at offshore sites in the bay was 8.03 ± 0.07 and at inshore sites was 8.04 ± 0.15. High pH variability (~0.55–0.61 pH units) was recorded at both offshore (>10 m depth) and inshore sites (intertidal surf zones). Many sites in the bay, especially the atypical site at Cape Recife, exhibit higher than the average pH levels (>8.04), suggesting that pH variability may be biologically driven. This is further evidenced by high diurnal variability in pH (~0.55 pH units). Although the specific drivers of the high pH variability in Algoa Bay could not be identified, baseline carbonate chemistry conditions were identified, which is necessary information to design and interpret biological experiments. Long-term, continuous monitoring is required to improve understanding of the drivers of pH variability in understudied coastal regions, like Algoa Bay. A local fisheries species, D. capensis, was selected as a model species to assess the impacts of future OA scenarios in Algoa Bay. It was hypothesized that this temperate, coastally distributed species would be adapted to naturally variable pH conditions and thus show some tolerance to low pH, considering that they are exposed to minimum pH levels of 7.77 and fluctuations of up to 0.55 pH units. Laboratory perturbation experiments were used to expose early postflexion stage of D. capensis to a range of pH treatments that were selected based on the measured local variability (~8.0–7.7 pH), as well as future projected OA scenarios (7.6–7.2 pH). Physiological responses were estimated using intermittent flow respirometry by quantifying routine and active metabolic rates as well as relative aerobic scope at each pH treatment. The behavioural responses of the larvae were also assessed at each pH treatment, as activity levels, by measuring swimming distance and speed in video-recording experiments, as well as feeding rates. D. capensis had sufficient physiological capacity to maintain metabolic performance at pH levels as low as 7.27, as evidenced by no changes in any of the measured metabolic rates (routine metabolic rate, active metabolic rate, and relative aerobic scope) after exposure to the range of pH treatments (8.02–7.27). Feeding rates of D. capensis were similarly unaffected by pH treatment. However, it appears that subtle increases in activity level (measured by swimming distance and swimming speed experiments) occur with a decrease in pH. These changes in activity level were a consequence of a change in behaviour rather than metabolic constraints. This study concludes, however, that based on the parameters measured, there is no evidence for survival or fitness related consequences of near future OA on D. capensis. OA research is still in its infancy in South Africa, and the potential impacts of OA to local marine resources has not yet been considered in local policy and resource management strategies. Integrating field monitoring and laboratory perturbation experiments is emerging as best practice in OA research. This is the first known study on the temperate south coast of South Africa to quantify local pH variability and to use this information to evaluate the biological response of a local species using relevant local OA scenarios as treatment levels for current and near future conditions. Research on local conditions in situ and the potential impacts of future OA scenarios on socio-economically valuable species, following the model developed in this study, is necessary to provide national policy makers with relevant scientific data to inform climate change management policies for local resources.
- Full Text:
- Date Issued: 2021
The performance and preference of a specialist herbivore, Catorhintha schaffneri (Coreidae), on its polytypic host plant, Pereskia aculeata (Cactaceae)
- Authors: Egbon, Ikponmwosa Nathaniel
- Date: 2019
- Subjects: Insects and biological pest control agents -- South Africa , Pereskia -- Biological control -- South Africa , Cactus -- Biological control -- South Africa , Coreida-- South Africa , Invasive plants -- Biological control -- South Africa , Catorhintha schaffneri
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68250 , vital:29223
- Description: Plant species moved beyond their natural ranges may be liberated into enemy-free spaces, where they increase resource allocation to fitness, rather than defence against natural enemies, and become invasive as suggested by the Evolution of Increased Competitive Ability (EICA) Hypothesis. Several cacti are notable invaders and are targeted for biological control. The leafy cactus, Pereskia aculeata Miller, introduced into South Africa from South America, has become a target for biological control after becoming invasive. The absence of natural enemies of P. aculeata in the introduced range may be the reason for its invasiveness. This thesis seeks to investigate the role of the evolution of increased competitive ability (enemy release) as the probable driver of P. aculeata’s success, and ascertain how the plant’s intraspecific variation influences the impact, fitness of, and preference by its biological control agent, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in South Africa. Enemy release and evolution of traits in P. aculeata were examined by quantifying plant growth parameters of fifteen genotypes of P. aculeata from both the native and invaded distribution of the plant. Ten genotypes of P. aculeata were used in testing the effect of agent herbivory (impact and damage) under similar conditions. These studies indicated that most invaded-range genotypes were more vigorous than the native genotypes. Rapid growth may account for the quick access of invasive genotypes of P. aculeata to tree canopies. Catorhintha schaffneri damage varied between genotypes but differences in the damage and impact from the agent could not be explained by whether the plant originated in the introduced or native distribution. In sum, while the growth of the invasive genotypes largely conforms to the EICA hypothesis, the impact of C. schaffneri did not support the hypothesis. The influence of host variation in P. aculeata on the fitness of C. schaffneri within the context of local adaptation to plant genotypes from different localities was tested using agent survival, stage-specific and total developmental time, and the extent of damage to ten host genotypes. Maw’s Host Suitability Index (HIS) and Dobie’s Susceptibility Index (DSI) showed the preference by and performance of C. schaffneri on the different genotypes of the plant. Catorhintha schaffneri survived to the adult stage on 70% of genotypes tested. Evidence consistent with the assumption that C. schaffneri would be fitter on the native genotypes than the invasive genotypes due to local adaptation was not found. In addition, there was no evidence in support of fitter agents on the invasive genotypes than on the native genotypes as proposed by EICA hypothesis. Catorhintha schaffneri developed equally well on the invasive genotypes of P. aculeata as on the native genotypes. To establish whether host variation would affect diet selection by C. schaffneri, both nymphs and adults were examined in paired-choice and multiple-choice trials. The nymphs and adults chose their hosts regardless of host genotype differences. The agent may be good at selecting good succulent shoots from bad shoots, but is incapable of distinguishing a good host genotype from a poorer one. This thesis shows, therefore, that P. aculeata and its array of genotypes in South Africa could be effectively controlled by C. schaffneri, as it has the potential to suitably utilise and impact the different genotypes of the weed in South Africa with neither any demonstrable preference nor local adaptation for the native genotypes. Consequently, the use of C. schaffneri, as a biological control agent in the weed biological control programme of P. aculeata remains promising, as the agent is insensitive to the intraspecific variation of the invasive host plants.
- Full Text:
- Date Issued: 2019
The incidence of musculoskeletal disorders and stakeholder perceptions of work challenges in South-Eastern Nigerian quarry mining industry
- Authors: Egwuonwu, Victor Afamerfuna
- Date: 2020
- Subjects: Quarries and quarrying -- Health aspects -- Nigeria , Musculoskeletal system -- Diseases -- Nigeria , Miners -- Health and hygiene -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141263 , vital:37957
- Description: Musculoskeletal disorders (MSDs) are very common among industrial labourers, leading to sick leave absence, disability and low productivity at work. MSDs have multifactorial causes, thereby making it difficult to pinpoint the extent of the contributions of the various risks regarding the mechanism of its pathophysiology. Previously, attempts were made to study regional pain symptoms in varying occupational groups, disregarding the particularities of the different workplace situations. It is important to highlight, that quantifying physical exposure factors that contribute to MSDs occurrence using quantitative approach alone could be inadequate. It is therefore imperative to incorporate qualitative approach to unmask accompanying psychosocial stressors, which are mostly explanatory variables. The study investigated the following: 12-month retrospective prevalence of MSDs, prospective incidence, risk factors and pattern of MSDs in a 6-month follow-up survey of selected quarry mineworkers, who reported MSDs complaints at the mine clinic. The study also determined the level of psychosocial stress associated with working in the mine by understanding stakeholders’ perception of work challenges, and how it influenced recurrence of MSDs. The study utilised a mixed method design with two phases: phase 1 was an initial baseline retrospective prevalence and a prospective cohort-control incidence survey. The Cultural and Psychosocial Influence on Disability (CUPID) questionnaire was translated into an Igbo-language version, cross-culturally adapted and utilized. The instrument was administered via oral interview and sought information on the following: demographic characteristics; pain in different anatomical sites and associated disability for tasks of daily living; as well as information on any change of job and reason during the study period, recent pain in different anatomical sites and associated disability for tasks of daily living; distress from common somatic symptoms; mental health status, sickness absence in the past 5-months for musculoskeletal pain. Phase 2 was a qualitative focus group discussion that engaged mine stakeholders on their perceptions of work challenges. Descriptive statistics of mean and standard deviation was utilised to analyse sociodemographic characteristics of participants. MSD incidence rates were estimated and the patterns of MSD incidence at different anatomical sites were also determined. The Cox proportional regression analyses were utilised to compare hazard ratios of MSD risks between the exposed cohorts and unexposed cohorts in the phase one incidence survey, alpha level was set at 0.05. Transcription, thematic and content analyses with the aid of Nvivo version 11 for windows was used to interpret stakeholders’ perception of work challenges. The incidence of MSD was 6.2 per 1000, with shoulder pain being the most reported complaint (40% prevalence). This was followed by back pain with the distribution of back pain presented as follows: upper back (20.37%), lower back (45.50%) and both (34.13%). All participants reported previous medical history of back, shoulder and neck pain. The relative risk ratio of mineworkers to MSDs was 4.57, which implies that the mineworkers were approximately 5 times more at risk of developing MSDs compared to the recruited unexposed cohorts. Meanwhile, wrist pain (43.58%) was the highest MSD complaints which lead miners to be absent from work, followed by knee and back with 35.42% and 21% respectively. Physical job risks, such as III working underground and squatting or kneeling at work were all significantly associated with MSDs recurrence in all six body parts (HR: 1.12-1.92, 95%CI). Similarly, time pressure to complete task, low decision latitude, poor job satisfaction, somatisation and mental disorder, job insecurity, poor incentive system (HR: 1.01-1.75, 95%CI) were perceived by stakeholders’ and participants alike in the study to be significantly associated with MSDs incidence. Quarrymen are exposed to high MSD risks associated with elevated psychosocial stress from their difficult work situations. The South Eastern Nigerian mine stakeholders believed that the high incidence of MSDs may have a substantial impact on health and productivity in the near future. Necessitating a clear need for the promotion of stakeholder’s engagement concerning safe work policy implementation initiatives in the sector.
- Full Text:
- Date Issued: 2020
Ecological consequences of non-native fish invasion in Eastern Cape headwater streams
- Authors: Ellender, Bruce Robert
- Date: 2014
- Subjects: Fishery management -- South Africa -- Eastern Cape Fishes -- Conservation -- South Africa Introduced fishes -- South Africa -- Eastern Cape Introduced organisms
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/69065 , vital:29380
- Description: The introduction, spread and concomitant impacts of non-native species are a global problem. Fish are among the most widely introduced vertebrate groups, with their impacts affecting multiple levels of organisation- from individuals, populations and communities, to entire ecosystems. In South Africa, the largest perceived threat to range-restricted endemic headwater stream fishes is said to be invasion by non-native fishes, however, as is the case elsewhere, invasive impacts are often a case of risk perception rather than actual risk analysis. Two range-restricted headwater species, the Eastern Cape redfin Pseudobarbus afer and the Border barb Barbus trevelyani are redlisted by the International Union for the Conservation of Nature (IUCN) as ‘Endangered’, primarily due to invasion by non-native fishes. To investigate invasions in South Africa, and provide a quantitative estimate of the impact of non-native fishes on the two imperilled endemics, P. afer and B. trevelyani, the overall aims of this thesis were to: (A) Provide a literature review on non-native fish invasions in South Africa; (B) Using two case studies on the headwaters of the perennial Keiskamma and episodic Swartkops River systems, investigate the naturalisation-invasion continuum to provide a holistic view of the invasion process in these variable environments. The specific thesis objectives were: (1) Reviewing current knowledge of invasive impacts of non-native fishes in South Africa; (2) Investigating invasibility of headwater stream environments by non-native fishes; (3) Determining the establishment success of non-native fishes, (4) Assessing the spatial and temporal impacts of invasion; (5) Understanding mechanisms responsible for non-native fish impacts; (6) Investigating the threat of non-native fish invasion on the genetic diversity of two the two headwater fishes, P. afer and B. trevelyani. Results from the literature review of fish invasions (Chapter 1) showed that South Africa has a long history of non-native fish introductions, spanning two and a half centuries. Currently, 55 species have been introduced or translocated. Many of these introduced species have become fully invasive (36%). Their impacts also span multiple levels of biological organisation. There was a general paucity of studies on fish invasions (38 studies), however, of those conducted, reviewed studies placed emphases on invasive impacts (25 studies) and the transport, introduction, establishment and spread stages of the invasion process were largely ignored. The two study systems, the Swartkops and Keiskamma Rivers, were heavily invaded and numbers of introduced species surpassed that of natives (Chapter 2, 3 and 5). Headwater streams had varying invasibility and a number of non-native species were successfully established (Chapter 2, 3, 5 and 6). The remainder of the invasions were casual incursions into headwater streams from source populations in mainstream and impoundment environments which were invasion hotspots. Irrespective of establishment, four predatory invaders (largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss) impacted heavily on native fish communities (Chapter 3, 4 and 5). Two broad types of invasion were documented, top down invasion by non-native O. mykiss and S. trutta and upstream invasion by M. salmoides and M. dolomieu (Chapter 3 and 5). Their impacts included changes in community structure, extirpation from invaded stream reaches resulting in contracted distribution, and isolation and fragmentation of native fish populations. The impacts of non-native predatory fishes were particularly acute for P. afer and B. trevelyani. Where non-native predatory fish occurred, P. afer and B. trevelyani had been extirpated (Chapter 3 and 5). As a result both native species exhibited contracted distributions (>20% habitat loss due to invasion). Upstream invasion by centrarchids isolated and fragmented P. afer populations into headwater refugia, while top down invasion by salmonids excluded B. trevelyani from invaded, more pristine stream reaches, by forcing the species into degraded unsuitable lower stream reaches. Predation also disrupted population processes such as adult dispersal for P. afer, and centrarchid-invaded zones acted as demographic sinks, where adults dispersing through invaded reaches were rapidly depleted. While the Mandela lineage of P. afer exhibited little within or between drainage genetic structuring, B. trevelyani was >4% divergent between drainages, and up to 2% divergent between streams within the Keiskamma River system (Chapter 7). The distribution of genetic diversity for B. trevelyani also indicated that the loss of diversity was imminent without immediate conservation interventions. This thesis has provided conclusive evidence that native fishes are vulnerable to invasion and that non-native predatory fishes have significant impacts on native fishes in Eastern Cape headwater streams. If management and conservation measures are implemented, the unwanted introduction and spread of non-native fishes may be restricted, allowing native fishes opportunities for recovery.
- Full Text:
- Date Issued: 2014
The trophic and spatial ecology of a sympatric dasyatid community at a remote Atoll, Seychelles
- Authors: Elston, Chantel
- Date: 2019
- Subjects: Dasyatidae -- Seychelles -- Ecology , Rays (Fishes) -- Seychelles -- Ecology , Ecology -- Seychelles , Dasyatidae -- Seychelles -- Conservation , Pastinachus sephen , Urogymnus granulatus , Urogymnus asperrimus
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/95756 , vital:31196 , DOI https://doi.org/10.21504/10962/95756
- Description: Batoid populations are declining globally but the paucity of information makes management or conservation efforts difficult. Additionally, batoids are mesopredators and are hypothesised to play important ecological roles, but a comprehensive understanding of these roles is also limited. Therefore, information on batoid habitat use, foraging ecology, and resource partitioning is needed. St. Joseph Atoll is a relatively pristine ecosystem that hosts a sympatric dasyatid community (Pastinachus sephen, Urogymnus granulatus, and U. asperrimus). Passive acoustic telemetry identified high levels of long-term site affinity by both juvenile and adult dasyatids to St. Joseph Atoll. Dispersal from the atoll by larger juveniles was also evident. Juveniles displayed restricted horizontal movements in the atoll, but the extent of these movements differed seasonally. Stomach content and stable isotope analyses identified inter-specific prey partitioning (P. sephen juveniles were mollusc specialists and U. granulatus juveniles were crustacean specialists) and intra-specific prey partitioning. Juveniles were reliant upon a seagrass-based food web, whereas adults were reliant on phytoplankton-based food web. Adults fed at higher trophic levels compared to juveniles (mean of 4.6 and 3.4 respectively). Juvenile dasyatids preferentially selected the shallow reef at habitat of the atoll, where there was no evidence for inter-specific habitat partitioning (individuals co-occurred randomly with con-and hetero-specifics). Conversely, resident adults were more reliant on the deeper lagoon. Juveniles selected the reef at habitat likely because it provided refuge from predation and foraging opportunities. However, juveniles were also detected in the lagoon habitat and this appeared to be necessitated by physical factors as they were detected more frequently in the lagoon at low tides and when temperatures on the reef fats became too warm or too cold. All results together suggest that St. Joseph Atoll is a nursery area for these dasyatids. Juveniles may be limited by resources as prey was partitioned between species. However, top-down control by larger sharks was likely a significant influence on habitat selection, as was the physical effects of tide and temperature. Finally, St. Joseph Atoll is suitable for the designation of a Marine Protected Area, which would likely confer high conservation benefits to this dasyatid community.
- Full Text:
- Date Issued: 2019
The isolation, characterisation and chemotaxonomic significance of secondary metabolites from selected South African Laurencia spp. Rhodophyta
- Authors: Fakee, Jameel
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64696 , vital:28593
- Description: Bioprospection of marine organisms as a potential source for lead drugs is becoming increasingly popular. The secondary metabolome of these organisms consists of structurally diverse molecules possessing unprecedented carbon skeletons, the biosynthesis of which occurs via complex metabolomic pathways driven by specialist enzymes. This structural novelty is highly influential on the favourable bioactivity these compounds display. A prominent example of such a compound is trabectedin marketed as Yondelis®. Registered for the treatment of soft tissue sarcomas, this marine drug was developed from extracts of the tunicate Ecteinascidia turbinata. South Africa is renowned for possessing a highly diverse marine biota including several endemic species of marine red algae belonging to the Laurencia sensu stricto genus, which falls within the Laurencia complex. Despite having a good reputation for fascinating secondary metabolites, the taxonomy of Laurencia natural products is proving challenging for reasons including the presence of cryptic species, as well as individual species displaying morphological variability. The aim of this study was thus to isolate secondary metabolites from various South African Laurencia spp. and subsequently assess their chemotaxonomic significance by analysis of a parallel plastid rbcL phylogeny study of Laurencia spp. This study reports the first phycochemical investigation into Laurencia natalensis Kylin, Laurencia cf. corymbosa J.Agardh, Laurencia complanata (Suhr) Kützing, Laurencia sodwaniensis Francis, Bolton, Mattio and Anderson submitted, Laurencia multiclavata Francis, Bolton, Mattio and Anderson submitted, and a South African specimen of Laurenciella marilzae Gil-Rodríguez, Sentíes, Díaz-Larrea, Cassano and M.T. Fujii (basionym: Laurencia marilzae) originally described from Spain. Additionally, the chemical profiles of previously explored species Laurencia flexuosa Kützing and Laurencia glomerata Kützing were re-investigated. The organic extracts of the above species afforded 31 compounds belonging to a wide array of structural classes including halo-chamigranes, linear C15 acetogenins, indole alkaloids, cuparanes and cyclic bromo-ethers. A new tri-cyclic keto-cuparane (4.4) was isolated from L.cf. corymbosa alongside the new cuparanes 4.1 and 4.7. Algoane (5.9), a unique marker compound isolated from L. natalensis, was previously only reported from a sea-hare. Such marker compounds which are exclusive to an individual algal species increase the ease of their subsequent identification. The feasibility of chemotaxonomy as an additional tool to classify Laurencia spp. Was established as broad predictions of a specimen’s phylogeny, based on representatives of its secondary metabolome, proved viable. The study specimens were shown to possess similar chemical profiles to their sister species e.g. L. complanata, L. sodwaniensis and L. multiclavata produced similar metabolites to their sister species as inferred by an rbcL phylogeny tree. Finally, a 1H NMR profiling study on the crude organic extracts of various Laurencia spp. generated distinctive, reproducible spectra, exposing the value of NMR spectroscopy as a rudimentary species discernment tool.
- Full Text:
- Date Issued: 2015
Evaluation of water quality, selected metals and endocrine-disrupting compounds in the rivers and municipal wastewaters of Eastern Cape province, South Africa
- Authors: Farounbi, Adebayo Ibikunle
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177327 , vital:42810
- Description: Thesis embargoed. Release date April 2022. , Thesis (PhD) -- Faculty of Science, Institute of Water Research, 2021
- Full Text:
- Date Issued: 2021-04
The current utility of oligonucleotide aptamers in targeting the MUC1 mucin tumour marker
- Authors: Flanagan, Shane Patrick
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62969 , vital:28348
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Dynamics of stimulated luminescence in natural quartz: Thermoluminescence and phototransferred thermoluminescence
- Authors: Folley, Damilola Esther
- Date: 2020
- Subjects: Thermoluminescence , Quartz
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146255 , vital:38509
- Description: Natural quartz has remained an important mineral that is of topical interest in luminescence and dosimetry-related research. We investigate the dynamics of stimulated luminescence on this material through thermoluminescence (TL) and phototransferred thermoluminescence (PTTL). Measurements were made on unannealed natural quartz as well as quartz annealed at 800 and 1000̊C. The samples were annealed for 10 minutes and for 1 hour. The material, in its un- and annealed state has its main peak between 68 and 72̊C when measured at 1Cs ̃1 after a dose of 50 Gy. A study of dosimetric features and kinetic analysis was carried out on two prominent peaks, peak I and III for all the samples. The peaks show a sublinear dose response for irradiation doses between 10 and 300 Gy. Kinetic analysis shows that peak I is a first-order peak and peak III a general-order peak. Interestingly, we observe for peak I for the sample annealed at 800̊C for 1 hour an inverse thermal quenching behaviour. We demonstrate that a peak affected with an inverse thermal quenching-like behaviour can still show effect of thermal quenching when the dose the sample is irradiated to is significantly reduced. We ascribe the apparent dependence of thermal quenching on dose to competition between radiative and non-radiative transitions at the recombination centre. Peaks I, II, and III for all the samples were reproduced under phototransfer when the peaks, initially removed by preheating to a certain temperature are exposed to 470 and 525 nm light. The infuence of duration of illumination on the PTTL intensity of these peaks corresponding to various preheating temperatures is modelled using coupled first-order dfferential equations. The model is based on systems of acceptors and donors whose number and role depends on preheating temperature
- Full Text:
- Date Issued: 2020
A multi-threading software countermeasure to mitigate side channel analysis in the time domain
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
Elevated CO2 determines cell damage and nitrogen allocation in barley subjected to aphid herbivory
- Authors: Gallagher, Sean
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64337 , vital:28535
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2018
Urbanisation, foraging and household food security in urban South Africa
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
- Full Text:
- Date Issued: 2020
Thermal physiology and behavioural ecology of the white shark, carcharodon carcharias
- Authors: Gennari, Enrico
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64002 , vital:28522
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2015
Tomographic imaging of East African equatorial ionosphere and study of equatorial plasma bubbles
- Authors: Giday, Nigussie Mezgebe
- Date: 2018
- Subjects: Ionosphere -- Africa, Central , Tomography -- Africa, Central , Global Positioning System , Neural networks (Computer science) , Space environment , Multi-Instrument Data Analysis System (MIDAS) , Equatorial plasma bubbles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63980 , vital:28516
- Description: In spite of the fact that the African ionospheric equatorial region has the largest ground footprint along the geomagnetic equator, it has not been well studied due to the absence of adequate ground-based instruments. This thesis presents research on both tomographic imaging of the African equatorial ionosphere and the study of the ionospheric irregularities/equatorial plasma bubbles (EPBs) under varying geomagnetic conditions. The Multi-Instrument Data Analysis System (MIDAS), an inversion algorithm, was investigated for its validity and ability as a tool to reconstruct multi-scaled ionospheric structures for different geomagnetic conditions. This was done for the narrow East African longitude sector with data from the available ground Global Positioning Sys-tem (GPS) receivers. The MIDAS results were compared to the results of two models, namely the IRI and GIM. MIDAS results compared more favourably with the observation vertical total electron content (VTEC), with a computed maximum correlation coefficient (r) of 0.99 and minimum root-mean-square error (RMSE) of 2.91 TECU, than did the results of the IRI-2012 and GIM models with maximum r of 0.93 and 0.99, and minimum RMSE of 13.03 TECU and 6.52 TECU, respectively, over all the test stations and validation days. The ability of MIDAS to reconstruct storm-time TEC was also compared with the results produced by the use of a Artificial Neural Net-work (ANN) for the African low- and mid-latitude regions. In terms of latitude, on average,MIDAS performed 13.44 % better than ANN in the African mid-latitudes, while MIDAS under performed in low-latitudes. This thesis also reports on the effects of moderate geomagnetic conditions on the evolution of EPBs and/or ionospheric irregularities during their season of occurrence using data from (or measurements by) space- and ground-based instruments for the east African equatorial sector. The study showed that the strength of daytime equatorial electrojet (EEJ), the steepness of the TEC peak-to-trough gradient and/or the meridional/transequatorial thermospheric winds sometimes have collective/interwoven effects, while at other times one mechanism dominates. In summary, this research offered tomographic results that outperform the results of the commonly used (“standard”) global models (i.e. IRI and GIM) for a longitude sector of importance to space weather, which has not been adequately studied due to a lack of sufficient instrumentation.
- Full Text:
- Date Issued: 2018
Waste management knowledge, its production, recontextualisation and circulation in Expanded Public Works Programme (EPWP) training programmes
- Authors: Giqwa, Nomfundiso Louisa
- Date: 2018
- Subjects: Refuse and refuse disposal -- South Africa -- Eastern Cape , South Africa. Expanded Public Works Programme , Refuse and refuse disposal -- Employees -- Training of -- South Africa -- Eastern Cape , South Africa. Department of Environmental Affairs , Knowledge, Theory of , Knowledge, Sociology of
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63729 , vital:28478
- Description: This study set out to investigate the structuring, recontextualisation and circulation of waste management knowledge in the South African environmental Expanded Public Works Programme (EPWP) Waste Management Projects. In this thesis these projects also referred to as the Working on Waste (WoW) programme or focus area within the Environmental Protection and Infrastructure Programme (EPIP) hosted by the National Department of Environmental Affairs. Expanded Public Work Programmes are a strategy used by governments to address unemployment and in South Africa; the programmes also seek to address a need for skills development. In this study, the focus is on EPWP waste management knowledge, training programmes and activities only. With waste management knowledge as the core interest, the focus of the investigation was on knowledge circulation of waste management via informal (participation in the project) and formal training of workers at Level 2 National Qualifications Framework (NQF). The study started by firstly investigating what waste management knowledge is produced in the Field of Production via scientific research and policy. It then studied how this waste management knowledge is recontextualised into qualifications and skills programmes designed in the official recontextualising field and learning materials and training programmes designed and offered in the professional recontextualising field. The study also focused on the knowledge of workers and their experience of training in the EPWP workplaces, with an emphasis on rural workplaces. This is where the Department of Environmental Affairs (DEA) is placing emphasis on training for job creation, empowerment and skills development, and it is also where a number of EPWP Working on Waste programmes are being implemented. The aim was also to develop an understanding of how knowledge circulates amongst learners in training sessions and in workplaces. To do this, I drew on Bernstein’s theory of the pedagogical device which provides theoretical lenses and a language of description to explain how knowledge is recontextualised from the field of production to the field of reproduction. To investigate the structuring of this knowledge by official and pedagogical recontextualisers, I drew on the work of Maton, who offers a Legitimation Code Theory to explain the principles structuring knowledge, of which I used specialisation and semantics (two of his suite of knowledge structuring principles) for analysis. The questions that guided the study throughout were: 1. What is the structure of legitimate knowledge and knowers in waste management? 2. What are the underlying principles underpinning knowledge and knowers in waste management? 3. How is the knowledge recontextualised in waste management training qualifications, documents and manuals for worker training at NQF Level 2? 4. How is the knowledge reproduced and evaluated in the waste management EPWP training activities (formal) and workplaces (informal)? 5. How does waste management knowledge circulate amongst the workers in the EPWP training activities and workplaces? For this study I used the case study method, focusing only on one field or DEA EPWP focus area (waste management) and one programme (EPWP Working on Waste), looking in more depth at two cases (two similar types of projects) within the EPWP Working on Waste programme, though they are situated in different areas and though I could only carry through observations of actual workplace training in one of the two sites due to contextual circumstances. The first project was situated in the Amathole District Municipality while the second one was situated in the Chris Hani District Municipality, both of which are in the rural towns of the former Transkei region in the Eastern Cape, South Africa. This area has been at the forefront in accessing funding for these projects due to the level of poverty surrounding these towns and the inability of the local government sphere to deliver on its mandate in the region. Data was collected through document analysis, questionnaires, interviews and observations. Documents analysed were research documents produced by researchers at the level of production as well as legal frameworks guiding waste management processes in this country. Qualifications and Unit Standards at Level 2, as well as training materials designed by providers were analysed. Training in one of the projects was observed and workers in both sites were interviewed twice. The main finding of the study is that waste management knowledge is characterised by interdisciplinarity and a strong epistemic relation which emphasises procedural and technical forms of knowledge. The study found that the knowledge constructed in the field, as well as the policies, qualifications and training programmes are all consequently characterised by a strong epistemic code (ER+) and a weak social relations code (SR-). The study also identified a ‘code clash’ with the knowledge of workers in rural towns whose knowledge and experience of waste management was found to reflect a strong social relation (SR+) and weak epistemic code (ER-), a pattern which was traced back to a similar code in waste management knowledge at home and school (i.e. workers’ prior knowledge and learning experiences). This created difficulties for the trainers who sought to use strategies of descending from the abstract to the concrete in various ‘descending’ semantic waves that tended to move from high levels of semantic density (SD+) to lower levels of semantic density (SD-) as the training provider sought to contextualise a range of concepts. This was the main strategy identified for mediating waste management knowledge reflecting a dominant pattern of SD+/SG- to SD-/SG+ (with SG meaning semantic gravity). This shows that the trainer seldom started mediating concepts from the basis of workers’ prior knowledge and experience and observations showed little responsiveness from workers resulting from this strategy. Despite this, the study found that workers did develop an improved understanding of specialised waste management knowledge over time, especially through observing and doing more complex tasks in the workplace. The study offers a model for addressing the pedagogical difficulty identified around the code clash, and suggests that further attention needs to be given to ‘ascending’ from the concrete to the abstract in pedagogical practices. The study also pointed to the need for a more inclusive knowledge framework for waste management training, especially in the field of recontextualisation (both the official and pedagogical recontextualisation fields) to extend possibilities for workers to learn more about economic potential and access routes into more sustainable jobs. It identifies the need for a more systemic approach to waste management in rural towns and municipalities, improved compliance and also proposes that better waste management practices are modelled to avoid performative contradictions between the knowledge promoted in the field of production and the official and pedagogical recontextualising fields and the field of reproduction, where workers are learning this knowledge via a mix of accredited training and exposure to participation in waste management practices. This study contributes to new knowledge in that it offers an epistemically grounded and theorised pedagogical process model for Level 2 Waste Management Training (in the EPWP programmes, but potentially also more broadly) that accords with the need for a strong epistemic relation code (ER+) embodied in the need for learning scientific and technical waste management knowledge and procedures. It also addresses workers’ needs for greater epistemic access and participation in knowledge building and application of waste management knowledge in praxis as per the purpose of the EPW training programmes, thereby potentially opening up more sustainable learning pathways for them out of poverty through the EPWP training opportunities. The study has pointed to key areas for further research, including further research on the proposed model, further research into Level 2 pedagogical practices and further research into the foundations of waste management learning in schools. Most of the workers who were participating in the training in the EPWP programmes were educated at above Level 2 before participating in the projects, yet their knowledge and experience of waste management was mostly based on everyday knowledge, pointing to an absence of adequate waste management education in schools in rural contexts in South Africa. The study has also made various recommendations for improving waste management education and training at Level 2 in EPWP programmes in rural areas in particular (but potentially also more widely), notably the need to develop a more inclusive knowledge framework that includes historical and economic knowledge more explicitly at all levels of the recontextualisation process; improved pedagogical and assessment practices that take better account of learners knowledge and experiences in knowledge building processes; and giving attention to structural and systemic approaches to waste management in rural areas to avoid performative contradictions that arise between the knowledge being promoted in the field of production and the field of reproduction and the actual context of waste management.
- Full Text:
- Date Issued: 2018
Perceptions of Ulwaluko in a Liberal Democratic State: is multiculturalism beneficial to AmaXhosa women in the Eastern Cape province of South Africa?
- Authors: Gogela, Kholisa B
- Date: 2018
- Subjects: Initiation rites -- South Africa -- Eastern Cape , Circumcision -- South Africa -- Eastern Cape , Stigma (Social psychology) -- South Africa -- Eastern Cape , Xhosa (African people) -- South Africa -- Eastern Cape , Women -- Attitudes , Multiculturalism -- South Africa -- Eastern Cape , Women's rights -- South Africa -- Eastern Cape , Male domination (Social structure) -- South Africa -- Eastern Cape , Sex discrimination against women -- South Africa -- Eastern Cape , Ulwaluko
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61780 , vital:28059
- Description: This exploratory qualitative study sought to investigate the views and perceptions of women on their experiences of ulwaluko, a traditional rite practised by amaXhosa in the Eastern Cape province of South Africa. Ulwaluko is also known as isiko lokwaluka or ukoluka in isiXhosa. The concept refers not only to the act of circumcision that occurs during the initiation ritual but the entire process a boy goes through in observing this practice. Ulwaluko is performed in the belief that it will transform boys into accountable and responsible citizens of the society who are fully committed and dedicated to the tenets and standards of nation building. All amaXhosa boys are expected to undergo this tradition to be considered men. Failure to go to the initiation school usually results in social stigma and complete banishment by the society. There is an abundance of literature on studies that have been conducted on male circumcision (and not ulwaluko) which is performed for hygiene and religious purposes worldwide. With regards to ulwaluko of amaXhosa, research studies that have been conducted appear to lean mainly towards biomedical and public health aspects of the ritual. There seems to be an even bigger proportion of studies whose objective was to examine the relationship between circumcision and HIV/AIDS. From the literature review, it was not difficult to observe the pervasive paucity of research studies on women in relation to initiation (and that of amaXhosa in particular), with regards to their inclusion or exclusion in the practice, their feelings, perceptions, experiences and attitudes towards the custom. It is for this reason that I found it crucial to conduct this study. The main research question I sought to answer in this investigation was: are the human rights and gender equality rights of women, as entrenched in the multicultural principles that underpin South Africa’s liberal, democratic order, adequately protected? In other words, could the individual rights of women (or gender rights) that are endorsed by liberalism, be deferred in the interest of respecting traditions and cultural values associated with ulwaluko? And if they are, I further ask: could the deferral of such rights be legitimate in the face of South Africa’s legal framework? The nature of this study places it in the qualitative paradigm, and interpretive phenomenology was the most appropriate research design to carry out the investigation. Multiculturalism is a principle at the centre of liberalism, and as a framework for this study, I contrast and reconcile it with feminism. While multiculturalism is concerned with protecting traditions and cultures of minority groups, feminism is concerned about women’s emancipation. I used the non-probability purposive sampling to select participants who were rich in information; and I made use of community structures to gain entry into research sites and to seek permission to carry out the investigation. I conducted the pilot study in Mdantsane, a township in the Buffalo City Municipality; and I gathered data in two research sites, namely: Flagstaff in Mpondondoland and Grahamstown in the Makana Local Municipality. I employed two qualitative methods to collect information, namely: focus group discussions (FGDs) and semi-structured in-depth interviews. A total of 70 participants took part in the study. 60 women participated in 8 focus groups and 10 participated in-depth interviews. Their ages ranged between 31 and 82 years. I recorded all the FGDs and semi-structured in-depth interviews that I conducted, for ease of transcription and translation. To interprete and analyze data, I applied the general inductive approach which I later substantiated with the use of NVivo 8, a computer assisted qualitative data analysis (CAQDAS). This resulted in the identification of four themes and their related sub-themes which I compared and contrasted with literature review and the theoretical framework, so as to make sense of the information I generated from the data collection process. I also discussed the results in line with the four goals of the study. The findings of this inquiry suggest a number of factors about ulwaluko, the following being the most significant: that firstly, although the rite is espoused and celebrated by some women as a significant cultural practice among amaXhosa, for others it is synonymous with patriarchy and hegemony. Secondly, women felt largely excluded, claiming that they were relegated to a subordinate position in society. For this reason, as well as because of the biomedical and other socio-political concerns associated with the practice, some women resented the custom. Thirdly, participants were divided about whether the practice should be continued or abolished; and these differences manifested within and between different regions. Fourthly, the results also demonstrated that the norms and values applied in ulwaluko are in contravention of the fundamental principles of a liberal state in that universal human rights are infringed upon through exclusionary practices. In this case the woman’s voice is muted; and this results in the denial of human agency. The study however, also revealed the emergence of shifting patterns in some parts of the province where an effort to include women appears to be taking place. Fifth and last, the enquiry demonstrated that ulwaluko is deeply entrenched among amaXhosa; that it has stood the test of time and is unlikely to be discontinued. Based on the results, I recommend that creative and transformative ways of addressing the evident clash between the provision of individual rights by the state and the recognition of ulwaluko as a cultural practice (which is perceived by some as harmful to women) be sought. To achieve this objective I make the following recommendations: 1) establishment and utilization of gender equality programmes; 2) modification of values and norms of the custom; 3) representation of women in decision-making structures; 4) establishment of collaborative networks; 5) widening of access to services (such as chapter nine institutions and national gender machinery); 6) documentation and sharing of effective and inclusive practices as well as; 7) creating awareness on initiation legislation.
- Full Text:
- Date Issued: 2018
The missing ingredient: rethinking the drought disaster risk reduction and climate change adaptation nexus in Chirumhanzu District, Zimbabwe
- Authors: Grey, Mashoko Stephen
- Date: 2018
- Subjects: Climatic changes -- Zimbabwe -- Chirumanzu District , Climatic changes -- Government policy -- Zimbabwe -- Chirumanzu District , Climatic changes -- Economic aspects -- Zimbabwe -- Chirumanzu District , Natural disasters -- Risk assessment -- Zimbabwe -- Chirumanzu District , Drought management -- Zimbabwe -- Chirumanzu District , Hazard mitigation -- Zimbabwe -- Chirumanzu District
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58298 , vital:27207
- Description: Two of the main challenges facing communities and governments in developing countries are the reduction of risks of hydro-meteorological hazards and adaptation to climate change. As climate variability and change impacts are becoming more visible in the form of disasters, and are negatively affecting climate sensitive livelihoods and eroding communities' ability to fully recover, leading to increased vulnerability to subsequent climate risks. The unpredictability of current weather systems, therefore, makes it very difficult for poor governments and households to deal with adverse impacts of climate change. Furthermore, the fragmented approach to DRR and CCA with regards to practice, policy and organisational frameworks for dealing with climate risks is resulting in coordination challenges for the government departments. This study aimed to explore how local households and communities perceive and are experiencing and coping with climate change and drought, and what that means for integrating hydro-meteorological disaster risk reduction and climate change adaptation. The study was carried out in Chirumhanzu district and the methods used for data collection included: 217 household surveys; six focus group discussions; participatory learning actions methods; key informant's interviews and document review. The majority of households owned low value material assets and had low levels of livelihood capitals and this exposed them to the impacts of climate variability and successive droughts. This low adaptive capacity largely affected their ability to engage effective drought risk reduction and adaptation strategies for their livelihood activities in small-scale farming and livestock rearing. Vulnerability to climate risks was exacerbated by seasonal weather forecasts, which were deemed by some households to be unreliable, inaccurate and not easily understood, while others used of indigenous knowledge. Successive droughts affected households' access to food and cash income for other household demands. Other non-climatic factors that contributed to adverse drought impacts at the household level were an emphasis on reactive humanitarian aid approach and the poor economy in Zimbabwe. Additionally, the policy framework for dealing with climate change and drought hazards is fragmented and weak; and is housed in different government departments making it difficult to coordinate and implement. To improve climate risk management, there is need for the government to appreciate that drought risk reduction and climate change adaptation are all about reducing vulnerability. Understanding this, might assist in improving government focus on addressing the underlying causes of vulnerability and mainstreaming DRR and CCA into development processes through addressing specific and generic adaptive capacities. The thesis argues that as long as rural households are involved in climate sensitive livelihood activities and not getting meaningful intervention to diversity and/or better intensify their livelihood activities, they will continue to be vulnerable to successive climate risks. This fragmented approach to dealing with climate risks, is not yielding any successful results with regards to building resilience, risk reduction or adaptation of rural households.
- Full Text:
- Date Issued: 2018
Livestock water productivity: towards improving rural livelihoods from livestock in semi-arid rangelands
- Authors: Gusha, Bukho
- Date: 2019
- Subjects: Livestock -- South Africa -- Eastern Cape , Livestock -- Effect of drought on -- South Africa -- Eastern Cape , Animals -- Food -- South Africa -- Eastern Cape , Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Livestock -- Water requirements -- South Africa -- Eastern Cape , Livestock productivity -- South Africa -- Eastern Cape , Stochastic analysis , Communal rangelands -- South Africa -- Eastern Cape , Land degradation -- South Africa -- Eastern Cape , Animal owners -- South Africa -- Eastern Cape , Livestock improvement -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115171 , vital:34084
- Description: Communal rangelands in South Africa mainly occur in the former homelands. The former homelands constitute 13% of the land surface area and support a quarter of the country's human population with a wide range of goods and services, among them, grazing for livestock, mostly reared on communal rangelands. These rangelands are degraded and cannot sustain maximum livestock production because of poor species composition and low standing biomass, however research has been conducted on livestock production at household level (where all livestock goods and services are valued). This provides an opportunity to conduct a study describing livestock water productivity in the north of the Eastern Cape, where livestock production is a primary source of livelihood for rural communities from which many households generate cash but where different practices and factors undermine high livestock production. Many studies have focused on understanding the water productivity of a natural rangeland system for commercially oriented crop-livestock systems, but the aim of this study is to contribute towards improving rural livelihoods from livestock in the sub-humid rangelands of the north Eastern Cape. Here, unimproved native grasslands are the major source of feed for livestock and people do not have herders to take livestock to the most productive parts of the rangelands. Households were surveyed using a questionnaire on livestock household contribution, socioeconomic characteristics of the household, livestock holdings and livestock production strategies. Rangeland productivity was measured in the field. Experimental animals for livestock grazing distribution were identified and fitted with Global Positioning Systems (GPS) collars to identify the seasonal grazing areas. These activities shed light on the biophysical attributes of the ecosystem and livestock production in a communal rangeland system. Because continuous grazing in the rangelands of the north Eastern Cape reduces the standing biomass, there is no obvious aboveground biomass to provide a visual perspective of production nor is it possible to determine production without excluding the livestock. Thus, four parallel lines of evidence were employed to measure rangeland productivity: line intercept, grazing exclosures, net photosynthesis from earth observation and disc pasture meter. Earth observation products were used to derive the amount of water used by the landscape to produce this forage (i.e. evapotranspiration or ET) and these measurements of net primary production and landscape water use were used in preparing a value of livestock water productivity (LWP) for this farming system. There has been the perception that residents of the study area lack knowledge of technical efficiencies in the large stock sector at household level. The study used stochastic frontier analysis to assess livestock production and followed with a household survey to collect information on socio-economic characteristics and information on livestock practices. The data from the household survey were used to estimate the technical efficiency of households using a stochastic frontier analysis. Productivity and inefficiency variables that increase livestock production or increase technical difficulties were identified. The focus on livestock has mostly been on the direct value of livestock to owners with a poor understanding of their value to non-livestock owners, where cultural activities, such as livestock slaughtering, were documented as the only source of protein for non-livestock owners. However, the value that is available to non-livestock owners has not been quantified. This study assessed livestockbased livelihoods of communal people to improve their livelihoods through a household survey looking at the contribution of livestock to both livestock and non-livestock owners. Earlier work on LWP has focused on systems where animals were on ‘fed, cut and carry’ and irrigated systems. However, there is a need to describe LWP in a natural grazing system and this study set out to achieve this for these communal rangelands through a household survey that determined the value of livestock goods and services given the amount of water used (ET). Lastly, livestock grazing distribution across the landscape was assessed, using GPS collars that recorded livestock behaviour every five minutes during the daylight. This approach was necessary because livestock grazing patterns in these communal rangelands is poorly controlled by people, and animals are largely free-ranging, grazing selectively, based on their own preferences, which leads to localised overgrazing. This part of the study was achieved through experimental livestock collaring and weighing (both sheep and goats) for the wet and dry seasons. The collared livestock were weighed on the day of putting on collars and the day of removing the collars. The results on livestock grazing distribution were analysed using the R package, T-LoCoH. The major finding of this study was that communal rangelands of the north Eastern Cape can improve rural livelihoods from livestock if proper interventions for both livestock and rangeland production and productivity can be implemented. One of these interventions is fencing as it was found that exclosures that were fenced during the study yielded high aboveground productivity comparable to that achieved in commercial rangelands, yielding 220 g DM m-2 yr-1. Surveys using the calibrated disc pasture meter showed the need for proper rotation and resting of the rangeland. Net photosynthesis of 880.7 g C m-2 yr-1 for unimproved grassland in good condition was comparable to commercial rangelands in the region. Using the line intercept, vegetation cover was found to be a good predictor of aboveground standing biomass; thus a positive relationship was revealed. Lastly, annual ET of 270 mm yr-1 was calculated using the Penman Monteith Palmer (PMP) equation, while 379 mm yr-1 was extracted from the MOD16 product, suggesting that PMP ET may not be accurate in these grassland systems due to the slow response of MODIS Leaf Area Index (LAI). The average household technical efficiency (TE) score was found to be 0.79 on the study sites, indicating the potential for households to improve outputs from livestock. A range of household categories were identified, based on gender and an index of wealth, and households with lower and higher TE were identified. This analysis revealed that productivity variables such as holding higher livestock numbers and providing additional feed achieved high livestock outputs, suggesting high livestock productivity. However, in terms of inefficiency variables, gender (female-headed households), dwelling type (an index of homestead wealth), kraaling livestock at night and herding livestock during the day were found to improve technical efficiency. It was revealed in this study that households keep livestock to derive different goods and services including offtake, manure, milk, wool and services such as traction. The non-livestock owning households were reported to also benefit from the abovementioned goods and services in the study site and that the value of their contribution could be quantified, thus contributing significantly to rural livelihoods. The study showed that LWP was comparable with other studies such as those conducted in Ethiopia. This study compared its results with the studies conducted outside South Africa as there were limited comparable South African studies available; however, this does not necessarily mean we can use the same model as the value of livestock outputs varies based on the preferred outputs. This study developed an LWP model for the natural rangeland system. The LWP values were measured in ZAR and later converted in USD and were divided into three different categories based on the wealth index, such as better-off, middle wealth and poor households. Lastly, this study showed that livestock (both cattle and sheep) spend a high proportion of their grazing day, during both the wet and dry seasons, in a small physical area, immediately around the homesteads. These are areas where the active green growth occurs throughout the year, suggesting the need for livestock herders to move livestock around the landscape for more effective landscape use. Herding has the potential to improve landscape use and conserve grazing resource and the ability of a household to attain best outputs from livestock. Positive daily weight gains were reported in collared livestock during the wet season. However, both sheep and cattle lost weight during the dry season. This study recommends interventions such as labour for herding, and other animal husbandry-related activities including milking, handling, and vaccinating animals. Market opportunities for communal rangeland livestock should be facilitated by informing livestock owners about livestock market specifications to improve their livelihoods. Lastly, proper grazing management planning, such as fencing, which enables rotational grazing, and herding which moves animals to the most productive parts of the rangeland, should be implemented so that rangelands can be rested for plant growth, vigour, and improved aboveground net primary productivity. Based on the recommendations made in this study, a research development approach is necessary which prioritises female empowerment in agriculture and poor farmers as female-headed households were reported by this study to be more technically efficient.
- Full Text:
- Date Issued: 2019
The further development, application and evaluation of a sediment yield model (WQSED) for catchment management in African catchments
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
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- Date Issued: 2021-04