Characterization of polarization dependent loss in optical fibres and optical components in the presence of polarization mode dispersion
- Authors: Pelaelo, Gaoboelwe
- Date: 2008
- Subjects: Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10528 , http://hdl.handle.net/10948/695 , Fiber optics , Polarization (Light)
- Description: In this study, the Jones matrix eigenanalysis (JME), optical spectrum analyzer (OSA) and polarization scrambling methods were used to investigate polarization dependent loss (PDL) in the presence of polarization mode dispersion (PMD) in optical components and fibres. The PDL measurements were conducted both in the laboratory and in the field. For field measurements, a buried link (28.8 km) and an aerial fibre (7.1 km) were extensively studied. The findings obtained from these studies are very important for network operators who must assess the impact of PDL on the network reliability. The three different PDL measurement methods (JME, OSA and polarization scrambling) were compared and their PDL values were found to agree very well at the selected wavelength of 1550 nm. Concatenation of PDL components showed that as expected, PDL increase as the number of PDL components were added. The interactions between PMD and PDL measurements were analyzed. A PMD/PDL emulator was constructed. We observed that PMD decreased while PDL increased. The PMD decrease was a result of the PMD vector cancellation enhanced by the randomly distributed mode coupling angles while PDL increase was a result of each PM fibre segments contributing to the overall global PDL. It was observed that the presence of PMD in a link containing PDL, results in PDL being wavelength dependent and this resulted in the extraction of the PMD information from the PDL data. PDL was found to be Maxwellian distributed when considering low values of PMD. High PMD values resulted in the PDL distribution deviating from Maxwellian. Long-term PDL and PMD (average DGD) measurements indicated that the PDL and PMD varied slowly with time and wavelength for both the laboratory and field measurements. It was observed that the BER increase as both PDL and PMD increased for simulated optical link.
- Full Text:
- Date Issued: 2008
Absenteeism management at Willard Batteries
- Authors: Paul, Gary William
- Date: 2008
- Subjects: Absenteeism (Labor) -- Management , Absenteeism (Labor) -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9383 , http://hdl.handle.net/10948/896 , Absenteeism (Labor) -- Management , Absenteeism (Labor) -- South Africa
- Description: The main research problem in this study centred around the assessment of the impact of an absenteeism monitoring and management system at Willard Batteries. The main research problem had five sub-problems which were addressed through the following actions: A literature study was conducted to identify the causes and impact of absenteeism in the workplace. The researcher also conducted interviews with the Human Resources Manager, line managers and employees at Willard Batteries to obtain their views of the absenteeism management strategies utilised, as well as the effects of absenteeism in their organisation. The insights gained from these interviews were incorporated into the questionnaire. The absenteeism figures of the organisation for the period 2005 to 2008 were analysed and compared against the internationally accepted absenteeism norm of three percent. An absence rate above three percent is considered as unacceptable and would imply that the current absenteeism management system is not effective. The theoretical study also entailed the reviewing of the legal framework within which absenteeism needs to be managed, as well as the literature that deals with strategies for the effective management of absenteeism. These strategies relate to the recording, calculation, analysis, benchmarking and practical management of absenteeism in the workplace. A survey questionnaire was developed to determine the perceptions of managers, supervisors and employees in relation to the impact of absenteeism on the company as well as the extent to which managers and supervisors were utilising selected absenteeism monitoring and management strategies within the company. The results from the empirical study revealed that management and supervisors were more aware of the impact of absenteeism on the organisation than their employees. It can therefore be concluded that employees perceived their absence from work to have little impact on aspects such as employee morale, cost, production and the customer. This could possibly be due to ineffective communication in terms of the cost and other consequences of absenteeism in the organisation. Employees also felt that managers were effective in taking the necessary disciplinary action with regards to absenteeism-related transgressions, but that they were not diligent in the recording and communication of absence information, as well as comparing absenteeism information inter-departmentally. Absenteeism has proven to be globally pervasive, expensive and extremely disruptive to organisations. Managers and supervisors who employ the various absence monitoring and management strategies, could be more effective in improving employee attendance. Their efforts could be further enhanced if employees are made aware of the negative impact that their absence has on the morale of their fellow employees, the cost to the company, the customer, as well as the achievement of production targets and the quality of outputs.
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- Date Issued: 2008
Larval fish dynamics in the shallow nearshore of Eastern Algoa Bay with particular emphasis on the effects of currents and swimming abilities on dispersal
- Authors: Pattrick, Paula
- Date: 2008
- Subjects: Fishes -- Larvae -- Eastern Cape -- Algoa Bay , Marine parks and reserves -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Ecology -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Dispersal -- Eastern Cape -- Algoa Bay , Fishes -- Development -- Eastern Cape -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5294 , http://hdl.handle.net/10962/d1005139 , Fishes -- Larvae -- Eastern Cape -- Algoa Bay , Marine parks and reserves -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Ecology -- Eastern Cape -- Algoa Bay , Fishes -- Larvae -- Dispersal -- Eastern Cape -- Algoa Bay , Fishes -- Development -- Eastern Cape -- Algoa Bay
- Description: The larval fish assemblage in the shallow, nearshore region of a proposed marine protected area (MPA) in eastern Algoa Bay, temperate South Africa was investigated. Current velocities and direction and the swimming abilities of late-stage larvae were further assessed to determine potential larval movement to and from the MPA. In total, 6045 larval fishes were collected along two depth contours (~5m and ~15m) in the shallow nearshore of eastern Algoa Bay using stepped-oblique bongo net tows, twice per season for two years (March 2005 – January 2007). These larvae represented 32 families and 78 species. The Gobiidae, Cynoglossidae, Clupeidae, Engraulidae and Sparidae were the dominant fish families. Catches varied significantly between seasons peaking in spring with a mean of 64 larvae/100m3. Preflexion stage larvae dominated catches (75%). All developmental stages of Diplodus capensis, Engraulis capensis, Heteromycteris capensis, Sardinops sagax and Pomadasys species were found in the study area. It appears that these species use the shallow nearshore as a nursery area. Analysis of 12 months (May 2006 – May 2007) data from a bottom-moored Acoustic Doppler Current Profiler within the study area showed that offshore south eastward (39%) and onshore north westward currents (33%) dominated. The south westward current (15%) and north eastward current (12%) occurred less frequently. Current velocity decreased with depth in the nearshore, with a mean velocity of ~29 cms⁻¹ recorded at a depth of 4 m and a mean velocity of ~11 cms⁻¹ recorded at a depth of 14 m. Understanding the dispersal and movement of marine fish larvae in coastal habitats requires knowledge of active swimming abilities. The critical speed and endurance swimming of late stage larvae of two common inshore species occurring in the study area, Diplodus capensis and Sarpa salpa (Family Sparidae), were measured in a laboratory swimming chamber. The mean U-crit value for D. capensis (18.6 cms⁻¹) was similar to that of S. salpa (18.0 cms⁻¹), whereas mean endurance (km swum) was greater in S. salpa (8.4 km) than D. capensis (5.9 km). These swimming abilities exceed the average current velocities observed in the shallow nearshore providing larvae with the ability to greatly alter their passive dispersal trajectories and ultimately influence their distribution in the nearshore.
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- Date Issued: 2008
Corporeal tales : an investigation into narrative form in contemporary South African dance and choreography
- Authors: Parker, Alan Charles
- Date: 2008
- Subjects: Sichel, Adrienne Krouse, Matthew Dance -- South Africa Choreography -- South Africa Choreographers -- South Africa Dance criticism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2157 , http://hdl.handle.net/10962/d1007658
- Description: In the years following the fall of Apartheid in South Africa, dance and choreography have undergone considerable transformation. This investigation stems from one observation relative to this change that has been articulated by two of South Africa's most respected dance critics, Adrienne Sichel and Matthew Krouse. Both critics have noted a growing concern for narrative in South African contemporary choreography, coupled with an apparent propensity for narratives of a distinctly personal and 'autobiographical' nature. In Part One: 'Just after the beginning', the proposed preoccupation with narrative in South African contemporary choreography is discussed in light of the relationship between narrative and the notion of personal identity. The use of the performed narrative as a medium to explore questions about identity is offered as one explanation underpinning this increased proclivity, where the interrogation of the form of the danced narrative provides a site for exploration of personal identity. Part Two: 'Somewhere in the middle' interrogates the notion of form through an in-depth discussion of the experimentation with form within theatrical and antitheatrical dance traditions over the last fifty years. Specific works by three selected South African choreographers (Ginslov, Maqoma and Sabbagha) are discussed in terms of their general approach to narrative form. This provides an illustration of some of the approaches to narrative form emergent in contemporary South African choreographic practices. Part Three: 'Nearing the end' offers Acty Tang's Chaste (2007) as a case study to illustrate the practical application of the dance narrative as a means to interrogate questions relating to personal identity. A detailed analysis of Tang's particular approach to forming the narrative of Chaste is conducted, exposing the intertextual, multimedia and multidisciplinary approach to creating the danced narrative.
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- Date Issued: 2008
Investigating the learners perceptions on the factors that influence learners to use and abuse drugs: a case study of one secondary school in the Eastern Cape Province
- Authors: Pama, Mzingisi Nimrod
- Date: 2008
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: vital:16160 , http://hdl.handle.net/10353/186
- Description: The research interest in this study was on learners’ perceptions on the factors that influence learners to use and abuse drugs. This study discussed learner understanding of drug use and abuse, what learners consider as reasons why learners use and abuse drugs and what could be done to discourage this phenomenon. The investigation was carried in the central region of the Eastern Cape in Fort Beaufort District. This district covers the rural areas of Nkonkobe municipality. I made use of qualitative methodology to obtain data from a sample of 56 learners and 12 teachers including the principal of the school. This study is located in one high school in the Fort Beaufort District. Methods used included learner surveys, learners’ focus group discussions, teachers’ focus discussions, learners individual interviews as well as document analysis. A major finding in this study indicates that learners understood what drugs as well as heir effects on those who use and abused them. The learners also unpacked factors that contribute to this phenomenon, which include peer pressure, socialization, stress and others. Teachers and learners also suggested ways in which drug use can be discouraged. Teacher also acknowledged that there was a drug problem amongst learners in their school and that something should urgently be done to discourage this phenomenon.
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- Date Issued: 2008
The feasibility of stock enhancement as a management tool for dusky kob (Argyrosomus japonicus) in South Africa
- Authors: Palmer, Ryan Michael
- Date: 2008
- Subjects: Argyrosomus -- South Africa , Argyrosomus -- Genetics , Fishery management -- South Africa , Fish stocking -- South Africa , Fisheries -- South Africa , Marine ecology -- South Africa , Fish culture -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5281 , http://hdl.handle.net/10962/d1005125 , Argyrosomus -- South Africa , Argyrosomus -- Genetics , Fishery management -- South Africa , Fish stocking -- South Africa , Fisheries -- South Africa , Marine ecology -- South Africa , Fish culture -- South Africa
- Description: The dusky kob, Argyrosomus japonicus, is a popular South African “line fish” whose stocks have dwindled to dangerously low levels of between 1% and 4.5% of pristine spawner biomass per recruit. A. japonicus stocks are currently managed by means of minimum size restrictions and daily bag limits, and as a result of the inability of these measures to facilitate the recovery of the species over a realistic time frame, the need for an alternative management plan has become apparent. Given the status of the stock and management regime, stock enhancement appears to be an appropriate option to be investigated. This study evaluates the feasibility of stock enhancement as a possible management tool to assist with the recovery of this important South African linefish species. By evaluating the genetic and ecological implications related to stock enhancement, identifying a suitable tagging method for post-release monitoring, and evaluating the economic feasibility of such a programme, any fatal flaws would become immediately apparent. This coupled with the required framework for the development of a management plan for stock enhancement of A. japonicus provides direction further research and actions required in order to utilise stock enhancement as a management tool. Due to the nature of stock enhancement, there are several ecological and genetic issues that arise from such a programme. These issues were reviewed and the issues that were relevant to stock enhancement of A. japonicus identified. Ecological concerns that arose included those of competition, disease and seed quality, while genetic issues were concerned mainly in the possible loss of genetic variability and consequent reduction in fitness of the stock. Fortunately the technology exists to evaluate the effects and likelihood of these problems occurring as well as to minimise the likelihood of them occurring. By taking a scientific approach to stock enhancement, hatchery management, and release strategies can be manipulated in such a way as to minimise any negative effects that may be caused. Both ecological and genetic effects of stocking indicate a need for post-release monitoring of stock enhancement programmes. Stock enhancement requires a post-release monitoring programme, which in turn relies on an ability to distinguish between hatchery reared and wild fish. A study was conducted to evaluate the suitability of coded wire tags (CWT), visual implant fluorescent elastomers (VIFE), and oxytetracycline (OTC) as a means of distinguishing between hatchery reared and wild A. japonicus, for the purpose of a post-release monitoring programme. OTC appeared to be the most suitable as it produced 100% retention over a five month period compared to 62% and 61% for VIFE and CWT respectively. OTC is therefore suggested as a tagging method for the purpose of post-release monitoring of the stock enhancement of A. japonicus. To evaluate a possible funding option for stock enhancement of A. japonicus in South Africa, a willingness-to-pay survey, based on a “user pays” approach using recreational fishing permits as a vehicle for payment, included 102 recreational anglers in the Plettenberg Bay area. The survey showed that generally anglers were willing to pay more than the current amount for the recreational fishing permit. This promising result, coupled with the fact that there are approximately 450 000 recreational anglers leads to the belief that there is potential for a substantial increase in the funds generated for the Marine Living Resources Fund through recreational anglers. Stock enhancement should not be ruled out on the basis of economic feasibility yet as there is potential for it to be sustained by the users of the resource. An A. japonicus juvenile production costing model was created taking into account setup and running costs of a hatchery for A. japonicus, based on known parameters from existing facilities, and adjusting them to meet the requirements of a stock enhancement facility. Estimates varied according to the number and size of fish for release (values which can only be decided upon after further research), with setup estimated to be between R 10 000 000 and R 30 000 000 and annual running costs between R 2 400 000 and R 6 700 000 annually. These figures were dependant on the size and number of fish being produced, with production ranging between 100 000 and 5 000 000 fish of between 50 mm and 150 mm, and a broodstock of 150 individuals. Given the need for alternative management of A. japonicus in South Africa and the lack of evidence to suggest that it is an unfeasible option, this project has found no reason why further investigation into the use of stock enhancement for the management of A. japonicus should not proceed further provided the fishery is shown to be recruit limited. The technology and ability to overcome possible ecological and genetic problems exists, a suitable means of tagging for post-release monitoring exists, as does a realistic funding option. There is a substantial amount of research that must be done prior to stocking, for which a base framework is provided.
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- Date Issued: 2008
Spatial and temporal variations in metals in the sediment and water of selected Eastern Cape Estuaries, South Africa
- Authors: Orr, Kyla Kathleen
- Date: 2008
- Subjects: Marine sediments -- South Africa -- Eastern Cape , Metals -- South Africa -- Eastern Cape , Metals -- Environmental aspects , Estuaries -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuarine sediments -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Water pollution -- South Africa -- Eastern Cape , Environmental toxicology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5769 , http://hdl.handle.net/10962/d1005457 , Marine sediments -- South Africa -- Eastern Cape , Metals -- South Africa -- Eastern Cape , Metals -- Environmental aspects , Estuaries -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuarine sediments -- South Africa -- Eastern Cape , Water quality -- South Africa -- Eastern Cape , Water pollution -- South Africa -- Eastern Cape , Environmental toxicology -- South Africa -- Eastern Cape
- Description: The spatio-temporal patterns in concentrations of selected metals within the sediment (Cd, Co, Cu, Fe, Pb, Ni and Zn) and water (Cd and Pb) of three permanently open estuaries (Kariega, Kowie, Great Fish) and six temporary open-closed estuaries (Mpekweni, East Kleinemonde, West Kleinemonde, Riet, Kasouga, Boknes) were investigated. The concentrations of metals were influenced by size composition and total organic content of the sediments. Enrichment factors (EFs), using Fe as a reference element, and baseline linear regression models for metals vs. Fe were calculated to assess the extent of metal enrichment in the sediments. The mean concentrations of metals in the sediments(mg·kg⁻¹) showed ranges of 0.28 – 2.31 for Cd, 1.26 – 6.24 Co, 0.69 – 6.93 for Cu, 2119 – 14912 for Fe, 2.29 –14.01 for Ni, 4.81 – 22.20 for Pb and 5.77 – 21.75 for Zn. Mean normalized enrichment factors ranged between 0.75 – 6.19 for Cd, 0.53 – 2.71 for Co, 0.22 – 0.84 for Cu, 0.30 – 1.87 for Ni, 0.99 – 3.17 for Pb and 0.14 – 0.98 for Zn. All nine estuaries had average enrichment factors of greater than 1 for Cd. In general there was no enrichment of Cu and Zn in the sediments of any of the estuaries included in this study (EFs < 1). The Kariega, East Kleinemonde, West Kleinemonde, Riet and Great Fish Estuaries showed some degree of enrichment for Co (1 < EF < 4), Ni (1 < EF < 2) and Pb (1 < EF < 4), while the Mpekweni, Kasouga, Boknes and Kowie Estuaries were unenriched with these metals (EF < 1). Enrichment factors for Cd, Co and Pb typically followed the development gradient along the estuaries, suggesting anthropogenic enrichment. The concentrations of Cd and Pb in the water of the nine estuaries were also determined. The average concentrations of Cd and Pb in the water (μg·ℓ⁻¹) ranged between 0.05 – 3.32 and 0.75 – 34.13 respectively. On average the concentrations of Cd and Pb in the water of all the estuaries were below the South African recommended water quality guidelines for coastal marine waters. Variations in metal concentrations associated with changes in hydrology (wet vs. dry season) were determined in the water and sediment of the Kariega, East Kleinemonde and Riet Estuaries. Cobalt, Pb and Ni enrichment in the Kariega Estuary sediment was significantly higher during the dry season, and the mean concentrations of Pb and Cd in the water column were 19-fold and 66-fold higher in the dry season. The elevated concentration of metals during the dry season could be related to accumulation of diffuse pollution from human activities within the catchment area. Conversely, inflow of fresh water into the estuary had the net effect of reducing the concentration and enrichment of these metals within the Kariega Estuary due to scouring and outflow of estuarine water and sediment into the marine environment. The temporal variations in metal concentrations and enrichment factors were less pronounced in the temporary open-closed estuaries than the permanently open Kariega Estuary. The observed trend can probably be related to the low anthropogenic impact within the catchment areas of these systems, and the relatively smaller size of the catchments. Significant spatial variations existed in metal enrichment in the sediment of both the East Kleinemonde and Riet estuaries, with the highest degrees of enrichment occurring in the sediments from the marine environment and lower reaches.
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- Date Issued: 2008
An investigation of the Ugandan publication Red Pepper: a case study from 2001-2004
- Authors: Opolot, Benedict
- Date: 2008
- Subjects: Red Pepper (Uganda) Sex in mass media -- Uganda Liberalism in mass media -- Uganda Homophobia -- Press coverage -- Uganda Mass media -- Political aspects -- Uganda Tabloid newspapers -- Uganda -- Case studies Newspapers -- Uganda -- 21st century Journalism -- Uganda
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3513 , http://hdl.handle.net/10962/d1007713
- Description: Red Pepper has been the subject of much discussion in Uganda, with some accounts describing it as a liberal mouthpiece, and others as pornography. This case study, therefore, sought to investigate Red Pepper as a media phenomenon in Uganda in the 21st century, specifically between 2001 and 2004. Employing quantitative and qualitative methodologies, it focused on the production process and the text. Although sexualised content dominate its pages, and news about issues such as the environment and education are near-absent, its managers describe the publication as legitimate, normative and consistent with liberal media standards. Accordingly, to interrogate Red Pepper in terms of its journalistic functions, selected debates associated with liberal approaches to news media, media political economy, tabloidisation, pornography and gendered relations were reviewed. The analysis entailed five phases. The first was a denotative or descriptive analysis, which focused on the publication's structure and content focus. This was followed by an interview with management, a broad content analysis to establish the incidence of predefined content categories expected of the tabloid, pornographic and liberal press and, lastly, a theme-based content analysis that sought to establish the potential meanings and framing of the dominant content categories of gossip and sexualised copy. Overall, the study found Red Pepper to be a misogynistic tabloid, having elements said to belong to pornography and homophobia. According to the findings, not only does Red Pepper fall short of a liberal understanding of a newspaper in terms of diversity of topics, provision of information and professional practice, it also does not fit the understanding of an alternative public sphere, mainly because it fails to challenge the patriarchal framing of sex, sexuality and gendered relations. This framing is undertaken deliberately as a means to securing economic rather than journalistic ideals to which the editors pay lip service. Consequently, the gossip and sexualised content are not problematised and as such discourses and power relations therein are not interrogated. Neither are inadequacies in local systems addressed nor corrective action mobilised as expected of some tabloids. All in all, the publication fronts superficial entertainment content that echoes particular gender constructions and patriarchal commonsense and entrenches the (undesirable) status quo which, ironically, it claims to challenge.
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- Date Issued: 2008
Geographic variation in the susceptibility of false colding Moth, Thaumatotibia Leucotreta, populations to a granulovirus (CrleGV-SA)
- Authors: Opoku-Debrah, John Kwadwo
- Date: 2008
- Subjects: Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Citrus -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10586 , http://hdl.handle.net/10948/984 , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Citrus -- Diseases and pests
- Description: The false codling moth (FCM), Thaumatotibia (=Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a serious pest of citrus and other crops in Sub-Saharan Africa. The introduction of the Cryptophlebia leucotreta granulovirus (CrleGV-SA) Cryptogran and Cryptex (biopesticides) has proven to be very effective in the control of FCM. However, markedly lower susceptibility of some codling moth (CM), Cydia pomonella (L.) populations to Cydia pomonella granulovirus (CpGV-M), another granulovirus product used in the control of CM’s in Europe have been reported. Genetic differences between FCM populations in South Africa have also been established. It is therefore possible that differences in the susceptibility of these geographically distinct FCM populations to CrleGV-SA might also exist. To investigate this phenomenon, a benchmark for pathogenecity was established. In continuation of previous work with Cryptogran against the 1st and 5th instar FCM larvae, dose-response relationships were established for all five larval instars of FCM. In surface dose-response bioassays, the LC50 values for the 2nd, 3rd and 4th instars were calculated to be 4.516 x 104, 1.662 x 105 and 2.205 x 106 occlusion bodies (OBs)/ml, respectively. The LC90 values for the 2nd, 3rd and 4th instars were calculated to be 4.287 x 106, 9.992 x 106 and 1.661 x 108 OBs/ml, respectively. Susceptibility to CrleGV-SA was found to decline with larval stage and increase with time of exposure. The protocol was used in guiding bioassays with field collected FCM larvae. Laboratory assays conducted with Cryptogran (at 1.661 x 108 OBs/ml) against field collected FCM larvae from Addo, Kirkwood, Citrusdal and Clanwilliam as well as a standard laboratory colony, showed a significant difference in pathogenecity in only one case. This significant difference was observed between 5th instars from the Addo colony and 5th instars from the other populations. Four geographically distinct FCM colonies from Addo, Citrusdal, Marble Hall and Nelspruit were also established. Since Cryptogran and Cryptex are always targeted against 1st instar FCM larvae in the field, further comparative laboratory assays were conducted with the Addo colony and an old laboratory colony. Cryptogran was significantly more pathogenic than Cryptex against both the Addo and the old colony. However, a high level of heterogeneity was observed in responses within each population.
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- Date Issued: 2008
Analysis of the extended defects in 3C-SiC
- Authors: Olivier, Ezra Jacobus
- Date: 2008
- Subjects: Crystals -- Defects , Crystallography , Silicon carbide
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10525 , http://hdl.handle.net/10948/730 , Crystals -- Defects , Crystallography , Silicon carbide
- Description: The dissertation focuses on the analysis of the extended defects present in as-grown and proton bombarded β-SiC (annealed and unannealed) grown by chemical vapour deposition (CVD) on (001) Si. The proton irradiation was done to a dose of 2.8 × 1016 protons/cm2 and the annealing took place at 1300°C and 1600°C for 1hr. The main techniques used for the analysis were transmission electron microscopy (TEM) and high resolution TEM (HRTEM). From the diffraction study of the material the phase of the SiC was confirmed to be the cubic beta phase with the zinc-blende structure. The main defects found in the β- SiC were stacking faults (SFs) with their associated partial dislocations and microtwins. The SFs were uniformly distributed throughout the foil. The SFs were identified as having a fault vector of the type 1/3 <111> with bonding partial dislocations of the type 1/6 <121> by using image simulation. The SFs were also found to be predominantly extrinsic in nature by using HRTEM analysis of SFs viewed edge-on. Also both bright and dar-field images of SFs on inclined planes exhibited symmetrical and complementary fringe contrast images. This is a result of the anomalous absorption ratio of SiC lying between that of Si and diamond. The analysis of the annealed and unannealed irradiated β-SiC yielded no evidence of radiation damage or change in the crystal structure of the β-SiC. This confirmed that β-SiC is a radiation resistant material. The critical proton dose for the creation of small dislocation loops seems to be higher than for other compound semiconductors with the zinc-blende structure.
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- Date Issued: 2008
Variation in the essential oil composition of Calendula Officinalis L
- Authors: Okoh, Omobola Oluranti
- Date: 2008
- Subjects: Calendula (Genus) , Essences and essential oils , Medicinal plants , Calendula officinalis
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11334 , http://hdl.handle.net/10353/d1001150 , Calendula (Genus) , Essences and essential oils , Medicinal plants , Calendula officinalis
- Description: Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80 percent of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 percent and 67 percent, the HD derived oil showed inhibitions of between 52.2 percent and 65.30 percent at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nosocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts
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- Date Issued: 2008
On the Processing of InAsSb/GaSb photodiodes for infrared detection
- Authors: Odendaal, Vicky
- Date: 2008
- Subjects: Gallium arsenide semiconductors , Photovoltaic cells , Infrared detectors , Gas-detectors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10523 , http://hdl.handle.net/10948/980 , Gallium arsenide semiconductors , Photovoltaic cells , Infrared detectors , Gas-detectors
- Description: The objective of this dissertation is the development of the necessary processing steps needed to manufacture infrared photodiodes on InAs1-xSbx material. Preliminary surface preparation steps were performed on both InAs and InSb material, thus covering both possible extremes of the antimony mole fraction. The first experiments endeavoured to characterise the effect of several possible etchants with regards to etch rate, repeatability, limitations for photolithographic patterning and the resultant surface roughness. The etchants investigated include a lactic acid based etchant, a sulphuric acid based etchant, an acetic acid based etchant, an ammonium based etchant, a hydrochloric acid based etchant as well as an organic rinse procedure. These cleaning and etching steps were evaluated at several temperatures. Measurements were performed on an Alpha Step stylus profiler as well as an atomic force microscope. Metal-insulator-semiconductor capacitor devices were manufactured, on both InAs and InSb material, in order to investigate the effects of the above-mentioned etchants combined with surface passivation techniques in terms of surface state densities. Capacitance-versus-bias voltage measurements were done to determine the resultant surface state densities and to compare these to the surface state density of an untreated reference sample. The surface passivation techniques included KOH, Na2S as well as (NH4)2S anodisation. Auger electron spectroscopy measurements were done on InAs and InSb material in order to examine possible surface contamination due to the etchants as well as combinations of these etching and anodisation procedures. The extent of surface coverage by contaminants as well as by the intrinsic elements was measured. The results of the cleaning and etching as well as the surface passivation studies were used to manufacture photovoltaic infrared diodes on an MOCVD (metal oxide chemical vapour deposition) grown p-InAs0.91Sb0.09/i- InAs0.91Sb0.09/n-GaSb structure. Current-versus-voltage and electro-optical measurements were performed on the these diodes in order to evaluate the effect of sulphuric acid based etching combined with KOH, Na2S or (NH4)2S anodisation on the detector performance. The results of surface passivated structures were compared to those of an unpassivated reference detector.
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- Date Issued: 2008
A study of the reintergration of former child soldiers : the case study of Gusco Northern Uganda
- Authors: Obika, Juliana
- Date: 2008
- Subjects: Children and war -- Uganda -- Gusco , Child soldiers -- Uganda -- Gusco , Soldiers -- Rehabilitation -- Uganda , Lord's Resistance Army
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:8256 , http://hdl.handle.net/10948/786 , http://hdl.handle.net/10948/d1012067 , Children and war -- Uganda -- Gusco , Child soldiers -- Uganda -- Gusco , Soldiers -- Rehabilitation -- Uganda , Lord's Resistance Army
- Description: The provision of basic needs such as food, shelter, security, identity and recognition is central in the rebuilding and reconstruction of the war-torn areas of Africa and indeed around the world. The war in northern Uganda, in particular, has taken its toll on the people of that area for more than 20 years and in the process, has witnessed the children facing some of the worst effects of armed conflicts known to man. This study investigated the role played by the Gulu Support the Children Organisation (GUSCO) in the reintegration of former child soldiers in Northern Uganda. GUSCO is however in favour of the term Formerly Abducted Children (FAC) as this is less prone to acts of stigmatisation against those who have faced some of the most horrific abuses known to human kind. It focused on the process of reintegration of the FAC in relation to the human needs theory which has been used as a basis for conflict resolution practices. The researcher conducted extensive face-to-face interviews with the employees of GUSCO who work in various fields as social workers, counsellors, health workers and teachers, who tend to the needs of the FAC daily. The researcher was also able to carryout observations of the activities that take place at the GUSCO reception centre where the children are rehabilitated. The organisation’s official documents were also consulted in order to carryout this triangular study and collect data. The major themes constructed from the study include: the empowerment and development of the FAC through education and skills training; health care provision to meet both physical and psychological needs; community empowerment and development and finally peacebuilding and reconciliation which involves the participation of whole communities to meet their needs and rebuild the war-torn northern Uganda. The researcher highlights some challenges that GUSCO faces in trying to reintegrate the former combatants albeit children into a routine of a community that struggles to recover from a war that continues to persist after twenty years. Several recommendations are made for GUSCO and civil societies who have given themselves the mandate to work towards salvaging the future generations of Uganda and Africa as a whole.
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- Date Issued: 2008
Tolerance in intergroup relations: cognitive representations reducing ingroup projection
- Authors: O'Sullivan, Clodagh M
- Date: 2008
- Subjects: Group identity , Social groups , Intergroup relations
- Language: English
- Type: Thesis , Masters , M Soc Sc (Psych)
- Identifier: vital:11604 , http://hdl.handle.net/10353/140 , Group identity , Social groups , Intergroup relations
- Description: This study assessed the personal, career and learning skills needs of 196 psychology students (M= 56, F= 103). The preferred means of counselling assistance, preferred experience of counselling and preferred counselling provider were also assessed. The most highly endorsed needs were time management skills (83.5 pecent, n=162), learning test-taking strategies (82 percent, n=159), job search strategies (73.6 percent, n=142), increasing self-confidence (70.3 percent, n=135), increasing motivation (72.4 percent, n=134), controlling anxiety and nervousness (68.7 percent, n=134), public speaking anxiety (68 percent, n=134), understanding career interests and abilities (67.5 percent, n=131), fear of failure (68.1 percent, n=130), and improving study skills (66.5 percent, n=129). Significant sex differences were found for the following, finding a greater purpose in life, controlling weight, job search strategies, concerns about career choice, understanding career interests and abilities in the selection of major subjects and improving study skills. Males highly endorsed the need for finding a greater purpose in life, job search strategies, and concern about career choice, understanding career interest and abilities, selection of major subjects and to improve study skills, whereas females endorsed the need for controlling weight. Respondents indicated individual counselling as being their preferred means of counselling assistance, but lectures were the most prevalent means of assistance previously received by respondents. Most respondents (78.1 percent) found the assistance they had received to be helpful.
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- Date Issued: 2008
Between hotel mama and petrol station manager: the represatations of women's realities in a selection of African films
- Authors: O'Reilly, Kevin Joseph
- Date: 2008
- Subjects: Motion pictures -- Africa , Women in motion pictures
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8404 , http://hdl.handle.net/10948/789 , Motion pictures -- Africa , Women in motion pictures
- Description: The roles that women perform as depicted in African films are often dictated to by the type of society they find themselves in. At first glance traditional societies can be seen as oppressive because of the presence of certain cultural practices. Alternatively modern urban settings appear to offer women authority and empowerment through employment. However, with a closer examination one sees that the situation is not so simplistic. Such is the case when certain traditional practices that are deemed oppressive through a Western perspective, are still found in urban societies. Films on the subject of African women have to be cautious not place their characters in stereotypical roles. Therefore, it is not enough to merely portray African women as ‘oppressed’. African films that engage in a feminist critique need to present ‘realistic’ portrayals of African women. Such characters are layered and complex. The film Faat Kine (2000) depicts such a character in the authoritative protagonist Kine. The film La Vie est Belle (1987) examines the issue of polygamous marriages and patriarchy from the point of view of two African women living in France. Touki Bouki (1973) examines two young characters living in Senegal and questions the possibility of escape from ones circumstances. Traditional practices such as polygamous marriages are explored in Xala (1975), and Finzan (1989) explores cultural practices such as forced marriages and female circumcision. This treatise will consider women and work in both traditional society and urban settings. African feminism will also be investigated for the purpose of exploring common social perceptions of women in Africa.
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- Date Issued: 2008
Home range dynamics of spotted grunter, pomadasys commersonnii, in a South African intermittently open estuary
- Authors: O'Connell, Bronwyn Anne
- Date: 2008
- Subjects: Grunts (Fishes) -- South Africa -- Eastern Cape , Pomadasys -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Estuarine fishes -- South Africa -- Eastern Cape , Estuarine fishes -- Habitat -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fishes -- Home range , Fishes -- Home range -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5286 , http://hdl.handle.net/10962/d1005130 , Grunts (Fishes) -- South Africa -- Eastern Cape , Pomadasys -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Estuarine fishes -- South Africa -- Eastern Cape , Estuarine fishes -- Habitat -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fishes -- Home range , Fishes -- Home range -- South Africa -- Eastern Cape
- Description: The spotted grunter (Pomadasys commersonnii) is an important, estuarine-dependent, fishery species in southern Africa. Since estuaries are essential habitats in the life history of this species, the quantification of area use patterns and movements is important for fisheries management. In this study, acoustic telemetry was used to investigate movements, use of habitat and home range dynamics of spotted grunter in the small intermittently open East Kleinemonde Estuary on the Eastern Cape coast of South Africa. Nine spotted grunter (range: 326-489mm TL) were surgically equipped with uniquely coded acoustic transmitters. Positional fixes were obtained by manual tracking tagged individuals on six days and six nights during five tracking sessions from March to November 2004. In addition, five stationary data-logging receivers, moored at specific locations from the mouth to the top of the estuary provided additional long-term monitoring. Kernel home ranges (95% UD) varied in size (26 296-165 321m²) but were all located in a common high use area situated between 300-1 300m from the estuary mouth, which coincided with the highest abundance of prey items. There was no significant variation in home range size [C² (N = 9, df = 4) = 4.18; p = 0.38] between the temporally segregated tracking sessions (over nine months). The persistence of these home range estimates were confirmed by the long-term data-logging receivers. There was no significant diel variation in home range size [F(4, 64) = 0.05, p = 0.99] or core area size [F(4, 64) = 1.40, p = 0.25]. Fish length showed negative, although not significant, relationships between home range size (p = 0.225); number of home range areas (p = 0.065); core area size (p = 0.512) and home range length (p = 0.320). Use of habitat and home range dynamics of spotted grunter in the East Kleinemonde Estuary were consistent over the nine month study period, and they appeared to be influenced more by biotic than abiotic factors. However, when the mouth opened at the end of the study, most tagged fish vacated their home ranges and emigrated to sea.
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- Date Issued: 2008
Application of the Baylis-Hillman methodology in the construction of novel heterocyclic derivatives
- Authors: Nyoni, Dubekile
- Date: 2008
- Subjects: Heterocyclic compounds -- Derivatives
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4402 , http://hdl.handle.net/10962/d1006704
- Description: Baylis-Hillman reactions of 2,2’-dithiodibenzaldehyde with the acyclic alkenes, methyl vinyl ketone (MVK) and methyl acrylate have afforded the thiochromene derivatives in moderate yields, and this approach has been extended to the use of the cyclic alkenes, 2-cyclohexenone and 2-cyclopentenone to afford the tricyclic analogues. In all cases, reduction of the disulphide link and intramolecular cyclisation occurred in situ, and a preliminary kinetic study of this reaction using the acyclic substrates MVK and methyl acrylate was undertaken with the aim of elucidating the mechanism involved. The results obtained showed that the consumption of both 2,2’-dithiodibenzaldehyde and MVK and/or methyl acrylate followed 1st-order kinetics during the initial stages of the reaction, but then deviated from 1st-order linearity. The reaction with methyl acrylate was much slower than with MVK, and the kinetic data indicates the mechanism to be more complex than anticipated. Conjugate addition reactions of methyl acrylate-derived 2-nitrobenzaldehyde Baylis-Hillman adducts with the amines, piperidine and benzylamine, afforded a range of conjugate addition products as diastereomeric mixtures in excellent yield (80-100%). Catalytic hydrogenation of the conjugate addition products using a Pd-C catalyst in ethanol, has afforded the corresponding, novel 3-amino-2-quinolone derivatives in lower yield (22-37%).The application of [superscript 13]C NMR prediction programmes to selected compounds synthesized in this study has revealed reasonable correlations between the experimental and predicted values.
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- Date Issued: 2008
An investigation into the management of HIV/AIDS programmes at the workplace in a highly volatile environment: a case study of selected organisations in Harare, Zimbabwe
- Authors: Nyemba, Taurai Booth William
- Date: 2008
- Subjects: Social responsibility of business -- Zimbabwe , Industrial hygiene -- Zimbabwe , HIV infections -- Zimbabwe -- Prevention , AIDS (Disease) -- Prevention -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MCom (Industrial Psychology)
- Identifier: vital:11549 , http://hdl.handle.net/10353/177 , Social responsibility of business -- Zimbabwe , Industrial hygiene -- Zimbabwe , HIV infections -- Zimbabwe -- Prevention , AIDS (Disease) -- Prevention -- Zimbabwe
- Description: The HIV/AIDS pandemic has had a devastating effect in the world, as it is now rated as the world’s greatest killer since its appearance in the mid 1980s. A UNICEF Report (2005) states that sub Saharan Africa is the hardest hit with countries like Botswana, Zimbabwe, South Africa, Namibia and Mozambique having an average of one in every five adults being infected. Sub Saharan Africa has less than 3 percent of the world’s population but it has an estimated 65 percent of the world’s population living with HIV/AIDS as it has 26 million of the 40 million infected people worldwide. In May 2003 the Government of Zimbabwe declared HIV/AIDS a national emergency a move that seems to have yielded results as the HIV prevalence rate has come down from 26.1 percent to 18.6 percent in 2005 and further to 15.6 percent in 2007. The Ministry of Health and Child Welfare (2004) states that if the prevalence had continued at 26.1 percent, about two thirds of today’s 15- year-olds would die from this disease. The deterioration of the political, social and economic situation since 1999 and the withdrawal of donor development support due to policy differences require concerted efforts from all parties concerned, now, rather than later. More commitment must be shown by private and public sector organisations to active participation in the establishing of effective workplace programmes, to assist employees, for the pandemic has placed a heavy strain on the health delivery system, as AIDS patients occupy between 50 percent to 70 percent of all hospital beds. Furthermore, the pandemic is killing the youth at the prime of their working careers so the pandemic, while being a health problem also has a negative macro-economic impact which may lead to a developmental crisis. A study was conducted of six organisations, using two questionnaires, one for management and one for non-management level employees. The study investigates whether the organisations had HIV/AIDS programmes and whether such programmes were effective. The findings were that all six organisations had HIV/AIDS programmes in place. However, some of the programmes were not effective because the employees did not know of their existence. Furthermore, it was found that management initiated awareness programmes and made condoms available but the employees were not changing their risky behaviour.
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- Date Issued: 2008
Investigating aspects of corporate citizenship on private game farms: the case of Mtshelezi Game Reserve in Makana Municipality, Eastern Cape Province
- Authors: Nyama, Cynthia
- Date: 2008
- Subjects: Tourism -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Agricultural laborers -- South Africa -- Eastern Cape -- Social conditions , Agricultural laborers -- South Africa -- Eastern Cape -- Economic conditions , Social responsibility of business -- South Africa -- Eastern Cape , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:751 , http://hdl.handle.net/10962/d1003872 , Tourism -- South Africa -- Eastern Cape , Game farms -- South Africa -- Eastern Cape , Agricultural laborers -- South Africa -- Eastern Cape -- Social conditions , Agricultural laborers -- South Africa -- Eastern Cape -- Economic conditions , Social responsibility of business -- South Africa -- Eastern Cape , Ecotourism -- South Africa -- Eastern Cape -- Citizen participation , Rural development -- South Africa -- Eastern Cape
- Description: Research show that post 1996 period has experienced an unprecedented increase in game based operations. The corporate citizenship or corporate social responsibility of the game reserves is of much interest to this study with a focus on the rights of previous and current occupants of farms, workers’ well-being, job creation, quality of life and poverty alleviation within the game/tourism industry. The research was conducted as a qualitative case study and the tools employed for data gathering include: a review of the relevant literature, interviews (face-to-face), the administering of a questionnaire survey and document analysis from diversity of resources which include the Department of Labour, East Cape Agricultural Research Project, and through use of multiple data sources. The approach taken in this dissertation is to examine to what extent the private game reserves in the Makana Municipality can be labelled as “corporate citizens” and this was done by means of a case study of one private game reserve. The areas that are deemed to be most important in this regard are (i) employment history (ii) educational opportunities (iii) wages (iv) housing (v) land tenure. The study established that younger, better educated people are likely to secure better paying employment on PGR. The nature and conditions of sale of the farm to the PGR can impact on the employment secured by workers in the new dispensation. Workers are tied to these jobs because of the very long hours that prevent them from doing anything else to earn money. Some of the workers had opportunities to learn new skills but the question remains; which people are these and how long will growing differentials in earnings reproduce the poorly educated worker in the next generation. The study also high lightened the need for academics and researchers to come with a common set of corporate citizenship measures such as to measure corporate social impacts.
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- Date Issued: 2008
Plant community distribution and diversity, and threats to vegetation of the Kromme River peat basins, Eastern Cape Province, South Africa
- Authors: Nsor, Collins Ayine
- Date: 2008
- Subjects: Kromme River (Eastern Cape, South Africa) , Peatland ecology -- South Africa -- Eastern Cape , Plant diversity conservation -- South Africa -- Eastern Cape , Peatland plants -- South Africa -- Eastern Cape , Peatlands -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Wetland conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4760 , http://hdl.handle.net/10962/d1007151 , Kromme River (Eastern Cape, South Africa) , Peatland ecology -- South Africa -- Eastern Cape , Plant diversity conservation -- South Africa -- Eastern Cape , Peatland plants -- South Africa -- Eastern Cape , Peatlands -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Wetland conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Description: This study examined the current plant diversity status and the impact of drivers of change on the peat basins of the Kromme River peatland. It was conducted at six sites over sixty one years in the Eastern Cape Province of South Africa. I reviewed the rapid habitat and biodiversity loss of wetlands globally and discussed the distribution of wetlands and specifically peatlands in South Africa. Plant species diversity was assessed using Modified- Whittaker plots. The influence of environmental variables on floristic composition and distribution was investigated using ordination techniques (DCA and CCA). Land use dynamics were assessed by applying GIS techniques on orthorectified aerial images. Six different peat basins were subjectively classified into good, medium and poor condition peat basins. The good condition peat basin (Krugersland) was the most diverse in plant species (4.1 Shannon-Weiner’s index) (p> 0.20; F = 11.04; df = 2), with the highest mean number of plant species (32.5 ± 3.4). This was followed by the medium condition class (Kammiesbos) (26.5 ± 9.0) and poor condition class (Companjesdrift) (22.5 ± 8.9). On average, species composition was not evenly distributed across the peat basins (p> 0.21; F = 0.94; df = 2), since 77.8% of the Shannon-Weiner evenness index obtained were less than one. However, there were variations in plant species richness across six peat basins as confirmed by Oneway ANOVA test (p= 0.0008, F = 1241.6, df = 4). Key environmental variables that influenced plant species distribution and structure were erosion and grazing intensity, potassium, phosphorus, soil pH and calcium. Total species variance accounted for in the first two axes for ground cover and plant height were 40.7% and 56.4% respectively. Alien species (e.g. Acacia mearnsii and Conyza scabrida) were common in degraded peat basins, whereas good condition peat basins supported indigenous species (e.g., Cyperus denudatus, Chrysanthemoides monolifera and Digitaria eriantha). Analysis of aerial images revealed a general progressive decrease in the peatland area between 1942 and 1969 in the good (Krugersland) and poor (Companjesdrift) condition class, with a marginal increase from 1969 to 2003. Peatland area in the good and poor condition class decreased by 5.3% and 8.3% respectively between 1942 and 1969, with a marginal increase of 1.5% and 4.1% respectively from 1969 to 2003. Annual net rate of change in peatland area over the 61 year period was -0.32% (good condition class) and - 0.79% (poor condition class). Transformed lands were impacted by drivers of change such as alien invasives, agricultural activities, erosion and sediment transport. The area under alien invasives increased by 50% between 1942 and 2003, with an annual net rate of change of +0.82 (good condition class) and +1.63% (poor condition class).
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- Date Issued: 2008