The contribution of small-scale fisheries to rural livelihoods and food security : evidence from Hamburg, Eastern Cape Province, South Africa
- Authors: Budaza, Nwabisa
- Date: 2018
- Subjects: Small-scale fisheries -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Fishery management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10338 , vital:35396
- Description: Small-scale fisheries are known to provide food and income to millions of people around the world, but their role and existence is often ignored in development planning. The growing human demand for animal protein has become one of the foremost world challenges for which aquatic organisms have a significant role to play. In South Africa, small-scale fisheries have been recognized since the end of Apartheid, but the extent of the contribution of the sector to rural livelihoods and food security is not well understood. Using data drawn from a sample of 80 fishers in the coastal community of Hamburg, Eastern Cape, this dissertation presents an assessment of the contribution of small-scale fisheries to rural livelihoods, income and food security. The primary data were collected from the fishers using a structured questionnaire and non-probability sampling. The data were analysed with the assistance of descriptive techniques and a few simply statistical tests. The results of the study indicate that fishers in Hamburg catch a wide range of fish, which include wild kob, octopus, spotted grunter, white/black mussel cracker and white steenbras. Fishers in the study area are not solely dependent on small-scale fisheries for their livelihoods, income and food security, but generally supplement their welfare payments with fishing in order to sustain their livelihoods. About 78percent of the surveyed fishers depend on government grants, including old age grants, child support grants and social care grant. In terms of employment, 15percent of the surveyed fishers are casually employed, while 6percent are formally employed on a contract basis. Although they are not only dependent on fishing, nevertheless fishing is an important source of livelihood, income and food security. About 37percent of the fishers harvest marine resources for home consumption, while 7percent harvest solely for income, and 56percent harvest for both home consumption and income. Income generated from fisheries is approximately R935 per month and is used to buy food, electricity, fishing equipment and other household needs. The findings from this research underline the need for interventions such as coordinated institutions, improved infrastructure, improved monitoring and enforcement systems, as well as improved access to permit/fishing rights for sustainable use of marine resources.
- Full Text:
- Date Issued: 2018
The development of natural fibre reinforced composites roof sheet
- Authors: Musikwa, Mufeba
- Date: 2018
- Subjects: Textile fibers -- Research , Textile fabrics Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32927 , vital:32398
- Description: The study aims to develop natural fibre reinforced bio-epoxy composite for use as roof sheets, manufacturing and characterization to evaluate its suitability for building applications. In this study natural fibres such as flax and kenaf were selected to reinforce bio-epoxy matrix. Different weight ratios of flax and kenaf fibres were processed by needle-punching technique to produce nonwoven mats. The nonwoven mats and bio-epoxy matrix were prepared using vacuum assisted resin transfer moulding (VARTM) at room temperature until dry and cured. The effects of weathering and water aging on the static and dynamic mechanical properties of kenaf and flax composites were investigated. Flax fibre reinforced bio-epoxy composites were found to exhibit higher tensile strength at 25% fibre content of 41.5 MPa in comparison to the composites reinforced with kenaf fibres (33.0 MPa). With regards to the drop weight impact results, flax fibre reinforced bio-epoxy composites exhibited brittle failure. Water aging results showed that kenaf fibre reinforced bio-epoxy composites absorbed less water for all fibre contents in comparison to composites reinforced with flax fibres. The tensile strength and modulus of both the composites reinforced with flax and kenaf fibres were reduced after water aging. However, the composite reinforced with kenaf fibres showed the maximum reduction in tensile strength at 25% fibre content. After UV treatment both composites reinforced with flax and kenaf fibres showed a decrease in tensile strength of 6.25% and 30%, respectively. In comparison to kenaf, bioepoxy composites reinforced with flax fibres showed an increase in tensile modulus. Both composites reinforced with flax and kenaf fibres were found to be brittle and broke easily but no colour fading was observed after UV treatment. The dynamic mechanical analyses results showed that the incorporation of flax and kenaf fibres increases the storage modulus of the composites with the maximum storage modulus value exhibited by flax fibre reinforced bio-epoxy composite at 30% fibre content. The glass transition temperature of composites reinforced with both flax and kenaf fibres shifted to lower temperatures of 79 °C and 69 °C respectively, in comparison to 96 °C for bio-epoxy resin, with the incorporation of fibres.
- Full Text:
- Date Issued: 2018
The development of rhenium(III) oxide nanoradiopharmaceuticals
- Authors: Joseph, Sinelizwi Veronica
- Date: 2018
- Subjects: Radiopharmaceuticals , Radiopharmaceuticals Rhenium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30507 , vital:30955
- Description: The study details the experimental work on the development of rhenium(III) oxide nanoradiopharmaceuticals for imaging and therapy of disease states. The nanoparticles (NPs) were capped with covalently linked tetraaminophthalocyanine-folate and ethylenediamine-folate to enhance their targeting ability. The capping agents were successfully synthesised and structurally characterised using Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform-Infrared Spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance (1H-NMR), and Liquid Chromatography-Mass Spectroscopy (LC-MS). The nanoparticles were characterised using UV-Vis, spectrofluorimetry, Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Zeta potential. Nanoparticles of sizes between 10 and 100 nm size were envisaged to be suitable for applications in biological systems. The preferred surface charge for the uptake of NPs must be between -30 and +30 mV, Re2O3 NPs capped with ethylenediamine were found to have a surface charge of -49 mV as compared with NPs capped with ethylenediamine-folate which gave -18.6 mV. The cytotoxicity studies of the nanoparticles were tested against four different cell lines: MDA-MB-468, MDA-MB-231, MCF-7, and MCF-10A. The cell survival rate after treatment was done with different capped rhenium(III) oxide nanoparticles obtained at a 10 μM concentration showed more than 80% cell viability. A comparison was conducted based on different nanoparticle sizes of capping agents across the four cell lines of varying folate receptor. All the cell lines were compared, and it was observed that MCF-7 had high percentage of cell viability especially with the cells treated with folate conjugated nanoparticles. Further investigation was done on the effects of folate conjugates and the effects of size. It was observed that the tetraaminophthalocyanine-folate favoured the MCF-7, for large-sized nanoparticles. However, further work is required to test the cancer cell internalisation of the nanoparticles using TEM as well as the correct size for endocytosis. Thereafter, the mice model study will be carried out for investigation of biodistribution of particles in tumour tissue using hot isotopes (186/188Re) and this will be done in a radiophamarceutical laboratory.
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- Date Issued: 2018
The development, manufacture and assessment of solid dispersions of gliclazide
- Authors: Govere, Grace Shalom
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63390 , vital:28405
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
The development, manufacture and evaluation of a selfmicro-emulsifying drug delivery system for efavirenz
- Authors: Musakana, Tanyaradzwa Gracious
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62643 , vital:28223
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
The effect of casuarina trees on sea turtles nesting beaches throughout the Indian Ocean and South-East Asia regions: A beach vulnerability assessment
- Authors: De Vos, Deidre
- Date: 2018
- Subjects: Conservation biology , Casuarina Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22420 , vital:29968
- Description: Rapid global change and anthropogenic modification of natural habitats are threatening ecosystems across the globe. Many of these threats and adverse impacts are concentrated on the world’s coastlines, with a large portion of the global population choosing to live next to the coast. To accommodate coastal populations and their related activities, the dynamic littoral active zone is often stabilized with hard engineering structures such as sea walls, which disrupt coastal ecological processes. Most natural coastal processes have since become natural disaster risks to the anthropogenically-modified coasts. Coastal stabilization has led to “coastal squeeze” with modified shorelines unable to respond naturally to changes in sea level. Furthermore, global change through global ‘warming’ exacerbates sea level rise. The combined impacts result in permanent/episodic inundation and coastal erosion, which may damage human settlements and degrade or destroy coastal habitat. As an alternative to hard armouring structures like sea walls, ‘soft’ options like large-scale plantations of trees as bio-shields are used as a ‘green’ option to protect developed coasts. Indeed, green shelter belts have rapidly increased since the December 2004 tsunami event in the Indian Ocean and South-East Asian (IOSEA) region. Extensive portions of the coastal habitat, including sensitive sea turtle nesting habitat, have been modified by planting exotic vegetation. Two invasive species, Casuarina equisetifolia and Casuarina glauca, are regularly used for coastal dune stabilization or as bio-shields because they are adapted to arid conditions, high salinity and low soil fertility typical of beach systems. The functionality of Casuarina trees as a ‘comprehensive’ coastal protection tool, however, has yet to be tested and the effects of Casuarina on sandy beach ecosystems remain largely unquantified. There is no empirical evidence to support the claim that Casuarina trees adequately function as a storm protection measure, and other studies have suggested that Casuarina species have adverse effects on sandy beach ecosystems, including the promotion of erosion in some instances and negative impacts on fauna, including sea turtles. This study investigated the potential value of non-native Casuarina trees as a coastal protection measure on sea turtle nesting beaches taking into consideration the potential impacts of global change. First, the study estimated local scale effects of Casuarina trees within the South African sea turtle nesting rookery in the iSimangaliso Wetland Park by measuring impacts on back-beach substrate characteristics and shape. A few metrics were unaffected, such as grain size, sand penetrability and sand moisture, but sand pH and sand temperature were significantly lower underneath Casuarina stands. A mean pH of 8.2 and a median temperature of 26 ± SD1.5oC were recorded under Casuarina trees and a pH of 9 and a median temperature of 27.2 ± SD1.9oC under native vegetation. The significantly lower, more stable average temperature underneath Casuarina trees may have significant implications for sex ratios of sea turtles as the sex of sea turtles is determined by temperature; Temperatures above 32°C will yield all females and temperatures below 28°C will produce only males, with a pivotal temperature at which a 1:1 sex ratio is developed is about 29°C. Furthermore, sand temperature underneath Casuarina trees is less likely to reach lethal temperatures (above ~33°C) that could lead to hatchling mortality than in areas with no vegetation. So, in terms of hatchling success, the thermal environment created by Casuarina trees might be favourable in extremely hot climate areas, especially when considering the effects of climate change. Casuarina trees, however, affect back-beach and dune dynamics by altering sand movement. Semi-quantitative and qualitative analyses of beach profiles suggested that Casuarina trees and shrubs result in wind scouring directly in front of the foredunes as evidenced by the concave shape in front of Casuarina stands at some sites. Sites with natural vegetation had mainly convex beach shapes, suggesting sand accretion. Either way, vegetation had an important effect on sand dynamics (both positive and negative) where areas with no vegetation (bare sand) only had a neutral/straight shape. There was, however, a significant interaction between vegetation type and site, indicating that vegetation type alone cannot account for all the differences in beach profile dynamics and that site-specific conditions like wave height, sand budget, precipitation and orientation differences among locations may also have an effect. The second part of the study had a regional perspective, investigating the effect of Casuarina trees on 50 sea turtle nesting beaches across the Indian Ocean South East Asia (IOSEA) region. The study first derived an appropriate (novel) beach vulnerability index using features that drive beach erosion. The index was then applied to 50 turtle rookeries in the presence/absence of Casuarina trees. The study noted the extensive distribution of exotic Casuarina trees throughout the IOSEA region and established that 28% of the 50 selected sea turtle nesting beaches had non-native Casuarina present. There was no significant difference in the erosion vulnerability of beaches with and without Casuarina based on the existing indicators. However, the study did show that seven important sea turtle rookeries were highly vulnerable to erosion, some with extensive exotic Casuarina stands. Olive ridley (Lepidochelys olivacea) nesting beaches in India, were dominated by Casuarina trees and were highly vulnerable to erosion. The study showed that the presence of Casuarina trees alone could not be viewed as an indicator of erosion but could be a contributing factor, as several other drivers like narrow back-beach width, absence of dunes and development on exposed coasts prone to storms, also contribute to the high erosion vulnerability of beaches. The study questions the use of exotic vegetation, such as Casuarina species, for coastal protection by demonstrating local scale effects on the back-beach environment and provides a comprehensive overview of the erosion potential of sea turtle nesting beaches throughout the IOSEA region.
- Full Text:
- Date Issued: 2018
The effect of ER stress in INS-1E cells using IL-1β under hyperglycaemic conditions
- Authors: Jackson, Simon
- Date: 2018
- Subjects: Diabetes -- Pathogenesis , Endoplasmic reticulum -- Pathophysiology Endoplasmic reticulum Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30397 , vital:30938
- Description: Diabetes afflicts millions of individuals worldwide, and the statistics rise each year. It is associated with various ailments which reduce the quality of life and has been shown to be associated with seemingly unrelated diseases or conditions. One aspect of the pathogenesis of diabetes is endoplasmic reticulum (ER) stress, which is an imbalance in the protein loading and protein folding capacities of the ER of a cell. Under chronic hyperglycaemic conditions associated with the development of diabetes, excessive insulin production disrupts the ER homeostasis, leading to ER stress. If the ER stress is severe or chronic, cell death of pancreatic β-cells may occur, leading to the onset of diabetes. There is currently a gap in available models that closely resemble the pathogenesis of diabetes in insulinoma-1E (INS-1E) pancreatic β-cells to study ER stress under hyperglycaemic conditions. This study optimised various ER stress-inducing models and tested terpenoid treatments to investigate their potential in modulating ER stress. Using various cell viability assays, five models to induce ER stress were optimised (hyperglycaemic, interleukin-1β (IL-1β), tunicamycin (Tm), brefeldin-A (BFA) and thapsigargin (Tg)). The five models were shown to induce ER stress through the expression of the downstream ER stress marker CCAAT-enhancer binding protein (C/EBP) homologous protein (CHOP). The various models induced ER stress under different mechanisms. Insulin secretion analysis using enzyme-linked immunosorbent assays (ELISAs) demonstrated that low concentrations of IL-1β promoted insulin secretion. Several of the terpenoid treatments showed potential in alleviating different aspects of either ER stress or inflammation.
- Full Text:
- Date Issued: 2018
The effect of water temperature on the distribution of the Eastern Cape redfin minnow, Pseudobarbus afer (Peters, 1864)
- Authors: Bloy, Lesley Elizabeth
- Date: 2018
- Subjects: Minnows -- South Africa -- Eastern Cape , Cyprinidae -- South Africa -- Eastern Cape , Minnows -- Effect of temperature on -- South Africa -- Eastern Cape , Minnows -- Effect of exotic animals on -- South Africa -- Eastern Cape , Introduced organisms -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62017 , vital:28096
- Description: The main objective of this MSc study was to disentangle whether temperature or the presence of non-native fish was limiting the distribution of Pseudobarbus afer (Peters, 1864) in the Blindekloof stream, Eastern Cape, South Africa. The aims were to: i) describe the thermal regime of the Blindekloof stream; ii) conduct experiments to determine the preferred and critical temperatures of P. afer and; iii) use snorkel surveys to contextualise the distribution of both native and non-native fishes in the Blindekloof stream to assess whether the downstream distribution of P. afer was likely to be influenced by temperature or by the presence of non-native, predatory fishes. To describe the thermal regime, year-long temperature data from four long term monitoring sites in the Blindekloof stream were collected using Hobo temperature loggers and analysed in order to better understand the thermal profile, the thermal variation and the rate of temperature change in the stream. The warmest temperatures were recorded in late December 2015 (absolute maximum of 29.4 °C). The coolest water temperatures were recorded in early August 2015 (absolute minimum of 9.5 °C). There is both seasonal and diel variation in temperature with mean, minimum, maximum, 7 day mean, 7 day maximum and temperature ranges differing significantly between sites. With knowledge of the thermal regime of a monitored reach of the Blindekloof stream, the thermal tolerance and preference of P. afer were investigated. The thermal tolerance of P. afer was investigated using the Critical Thermal Method (CTM) which uses non-lethal endpoints (the loss of equilibrium). At low acclimatization temperatures (11.9 ± 0.7 °C), the mean CTmax of P. afer was found to be 29.9 ± 0.7 °C, while at a higher acclimatization temperature (19.9 ± 0.1 °C), the mean CTmax was 35.1 ± 0.6°C. Custom-built thermal choice tanks were used to investigate the thermal preference of P. afer in both summer and winter. The preferred median temperatures for the summer experiments ranged from 22.4 - 29.3 °C while the winter preferred median temperatures ranged from 18.5 - 23.1 °C. The thermal tolerance of P. afer was compared to the thermal regime of the stream and the results suggest that temperature is not limiting the distribution of P. afer. Snorkel surveys were used to determine the distribution of fishes in the Blindekloof stream. Analysis of the distribution data suggests that, in the absence of non-native predatory species, native fishes have the potential to inhabit pools throughout the system right to the confluence, thus predatory fishes and not temperature was limiting P. afer distributions.
- Full Text:
- Date Issued: 2018
The effects of intermittent task parameters on muscle fatigue development during submaximal dynamic exertions
- Authors: King, Josephine Claire
- Date: 2018
- Subjects: Muscles -- Physiology , Muscles -- Wounds and injuries , Fatigue , Human engineering , Occupational diseases
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63855 , vital:28498
- Description: The negative effects of localised muscle fatigue on accidents, injuries and poor work performance are well known, as is the realisation that modifying task characteristics can minimise fatigue development. A large amount of literature has investigated the effects of task-dependent factors on localised muscle fatigue, most studies have focussed on prolonged or intermittent static (isometric) exertions. Few studies have investigated muscle fatigue development during more complex tasks, namely those which resemble common work activities and which tend to be intermittent and dynamic in nature. More specifically, the interactions between the main intermittent parameters - duty cycle, force level, and cycle time - during dynamic exertions are poorly understood. The purpose of this study was to investigate the effects of cycle time and combinations of duty cycles and force levels on the development of muscle fatigue during submaximal dynamic exertions while the overall mean muscle load was kept constant. A two-factorial repeated-measures experiment was developed for this study. Nine experimental conditions, each lasting 16 minutes, aimed at inducing muscle fatigue in the middle deltoid muscle via intermittent dynamic shoulder abduction and adduction motions at three cycle times (30, 60, and 120 seconds) and three combinations of duty cycles and force levels. The percentage of muscle activation during one cycle (i.e. the duty cycle) varied depending on the exertion intensity (force level) so that the overall mean muscle load remained consistent throughout all experimental conditions, namely at 20% of maximum force exertion. As a result, the three duty cycle/force level combinations were: 0.8/25% of maximum voluntary force (MVF), 0.5/40%MVF, and 0.4/50%MVF. Muscle fatigue development was inferred by changes in peak torque, total work, average power, local Ratings of Perceived Exertion (RPE), and surface electromyographical (EMG) activity (time domain and frequency domain).Two-factorial analyses of variance with Tukey post-hoc tests were used to identify significant condition effects at p<0.05. All dependent measures showed that muscle fatigue was induced by the 16-minute fatigue protocol. Peak torque, total work, average power, and EMG percentage of maximum showed that cycle time and the duty cycle/force level combination had no effect on the development of muscle fatigue, whereas the measures evaluated during the 16-minute fatigue protocol did. The cycle time of 120 seconds induced the greatest change in six of the eight variables, while the duty cycle/force level combination (0.8/25%) also resulted in the greatest effect in six of the measures. Fatigue was also found to be dependent on the interaction of cycle time and duty cycle/force level combination. The conclusion draws from this study is that shorter cycles and activities with short activation periods, and proportionally longer rest breaks result in the lowest fatigue developments.
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- Date Issued: 2018
The evaluation of potential dietary media, measurement parameters and storage techniques for use in forensic entomotoxicology
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
The foraging ecology of Wedge-tailed Shearwaters (Ardenna Pacifica) in the tropical Western Indian Ocean
- Authors: Keys, Danielle Zuanda
- Date: 2018
- Subjects: Birds of prey -- Behavior -- South Africa -- Western Cape , Animal behavior , Wildlife conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31251 , vital:31348
- Description: The distribution and abundance of prey largely influences how marine predators forage. Thus, understanding how marine predators respond to such changes becomes imperative when making decisions in marine spatial planning, especially in light of global climate change. Tropical marine systems are known for their relatively low productivity and high unpredictability of prey resources. Compared to higher latitudes, very few studies on seabirds have been implemented in the tropics. The Wedge-tailed Shearwater Ardenna pacifica is an Indo-Pacific tropical seabird with a wide distributional range. However, like many other seabirds, its population numbers are currently declining. Very little is known about the at-sea distribution of Wedge-tailed Shearwaters in the tropical western Indian Ocean. Therefore, this thesis investigates the foraging ecology of Wedge-tailed Shearwaters in the western Indian Ocean by tracking the fine scale movements of individuals at sea. This study was conducted in two different oceanic environments, namely D’Arros Island and Fouquet Island, St Joseph Atoll in the Amirantes Group in Seychelles archipelago as well as Réunion Island in the Mascarene archipelago during the Wedge-tailed Shearwaters breeding seasons. Here I aimed to investigate the foraging distribution of Wedge-tailed Shearwaters on Réunion Island in relation to different stages of the breeding period. I also compared the foraging ecology of all three populations, subjected to different abiotic and biotic factors. Furthermore, I investigated foraging site fidelity in individuals and repeatability within individual flight characteristics. To my knowledge, this is the first study to comprehensively investigate the foraging ecology of Wedge-tailed Shearwaters using global positioning system (GPS) loggers. This study demonstrated that the Wedge-tailed Shearwaters implement flexible foraging strategies throughout different stages of their breeding period and between different islands. In Réunion, during the shearwater breeding season, sexual segregation was prominent during early chick rearing and both sexes implemented dual foraging. As suggested by previous studies, it is likely that long trips were implemented for self-maintenance, whereas multiple short trips were implemented to meet the high energetic demands of the chicks. Several important foraging areas were identified for these Wedge-tailed Shearwaters. During incubation, shearwaters from Réunion faithfully foraged towards the south east of Madagascar near the East Madagascar Current and flew over large areas of the Mascarene Basin. During chick rearing, shearwaters significantly constricted their range closer to the colony and exploited deep waters on the south-west of Réunion Island. Shearwaters concentrated near oceanographic features such as the Pérouse Seamount (which is a known area of high productivity) as well as the Bourdonnais Ridge. There was no clear evidence for spatial or sexual segregation between individuals from the two study colonies in Seychelles during incubation and birds utilized a broader foraging range than birds from Réunion. This is likely to be the result of a large annual phytoplankton bloom which coincides with the shearwater breeding season in Seychelles, providing many foraging opportunities within the Seychelles Basin. The shearwaters from Seychelles exploited the Amirante Basin, East Somali Basin, and parts of the Seychelles archipelago. Shearwaters from D’Arros flew further east and foraged in the Mascarene Basin. Shearwaters from all populations foraged over deep, relatively unproductive waters with relatively high sea surface temperatures which are similar oceanographic features favoured by tuna. Foraging plasticity between individuals from different colonies was observed with varying flight bearings, flight durations and the maximum distances travelled from their respective colonies. Shearwaters displayed dissimilar levels of site fidelity, where shearwaters from Réunion faithfully foraged towards south east Madagascar, while shearwaters from Seychelles foraged over a wide range over the Seychelles Basin. Foraging effort for shearwaters from Fouquet was lower than shearwaters from Reunion and they spent less time at sea and foraged closer to their colony. These difference in behaviour responses between colonies may be advantageous to shearwaters, indicating that they may be able to respond to some level of environmental variability resulting from climate change and anthropogenic pressures. Lastly, during chick rearing, though shearwaters showed low levels of repeatability in flight characterising, foraging site fidelity was high amongst some of the individuals. Here we see that shearwaters continuously rely on permanent features, like seamounts and possibly fish aggregating devices, which are known to attract high abundances of tuna. Shearwaters may to some extent be relying on memory to find prey in a seemingly unpredictable environment. This study has helped us gain valuable insight about the foraging ecology of Wedge-tailed Shearwaters in the western Indian Ocean. Together with similar studies determining the at-sea behaviour of seabirds, better informed recommendations can be made to marine spatial planners as to where much needed pelagic marine protection should be implemented to preserve marine life in this fascinating part of the global ocean.
- Full Text:
- Date Issued: 2018
The impact of project performance on the image of the construction industry in Botswana
- Authors: Ndadi, Thabo Enert
- Date: 2018
- Subjects: Project management -- Botswana , Construction industry -- Botswana Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32826 , vital:32367
- Description: The construction industry is one of the largest sectors in the economy of Botswana, and contributes significantly to the socio-economic development of the country, averaging 6.7 per cent of the country’s gross domestic product (GDP). Botswana operates a free enterprise system where anyone is free to participate, which is supported by the existence of multi-national construction firms operating in the country. The construction industry in Botswana consists of various role players. As a developing country, Botswana’s construction industry is facing challenges of poor project implementation. The performance of the construction industry has not escaped the public‘s scrutiny of commercial construction and social development projects, resulting in negative perceptions with respect to the sector. This study focuses on the impact of project performance on the image of the construction industry in Botswana, and was conducted on projects underway. When public opinion is formed, a certain image of the business results, therefore the investigation endeavoured to establish the sources of negative perceptions towards the construction industry. To realise the aforementioned study objectives, an exploratory design sequence method was adopted henceforth applying established and tested quantitative and qualitative systems. A questionnaire was formulated and established to obtain the empirical data on randomly selected projects that were on-going or completed in the past ten years .These included public sector projects, private sector and those undertaken by parastatal organisation. The sample stratum deemed representative picture of the population, included various construction industry stakeholders. To facilitate for an effective data to inform the study, the questionnaire was categorised in three key areas of, biographic data, demographic and the industry best practice perceptions. The study determined that the capability of firms is influenced by construction management skills, and established regulatory systems. These can determine the extent to which the construction industry delivers the project within the business environment that is guided by the micro, macro and market parameters. As evidenced in the findings, the Botswana construction industry faces a skills’ gap and therefore is reliant on imported labour, and many international firms operating in the country affirm this observation. The study also addressed the existing regulatory systems, and the effectiveness of institutions. The study concludes that the existing performance regulatory systems are not adequate or they are ineffectively controlled; industry role players’ behaviour is irresponsible; there is limited skills’ capacity, and political interference accompanies project implementation. While the deterioration in the construction industry can be attributed to imported culture, it is noted that multi-national corporations (MNCs) and other foreign firms can be conduits for technology and knowledge (T&K) transfer to host countries in the developing world. Botswana with its free enterprise market and limited skill capacity and informed by the behaviour of construction industry role players, there is need for a structured integrity restoration process from both regulator and the operators. There is further need for a specific sector regulatory instrument (Act) to regulate the safety, health, and environmental operations in the construction industry. The construction industry also need to support research and development of the industry to be competitive both local and international.
- Full Text:
- Date Issued: 2018
The impact of the construction regulations 2014 on a water utility’s projects’ health and safety performance in South Africa
- Authors: Malindi, Rajandree Mandy
- Date: 2018
- Subjects: Construction industry -- Safety regulations -- South Africa , Construction industry -- Standards -- South Africa Construction industry -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31655 , vital:31645
- Description: The construction industry plays a major role in South Africa’s economic development. Since promulgation of the Construction Regulations, the expectation is that project stakeholders are placing more emphasis on H&S to contribute to project success. The study aimed to assess the impact of the involvement of clients and other project stakeholders on the overall project H&S performance on projects undertaken by a large water utility. The scope was limited to the organisation’s engineering and operations division and its internal project stakeholders, namely the designers, quantity surveyors, project managers, and construction H&S professionals. Local literature pointed out that poor construction H&S performance is attributable to a lack of management commitment, inadequate supervision, inadequate or lack of H&S training, lack of worker involvement, personal risk appreciation and work pressures (cidb, 2009: 37). International literature indicated that the total CoA exceeds the cost of H&S (cidb, 2009: 9). Quantitative methods were utilised in two phases to gather and analyse data. In Phase 1, a questionnaire was developed and distributed to a target population, and in Phase 2, data was obtained from existing records of historic and completed project files for projects undertaken by the water utility. A total of 67 responses were used to analyse data. All stakeholders somehow contributed to H&S however, most respondents regarded CHS professionals, contractors and PMs as the primary stakeholders. The study found that stakeholders perceived H&S to be influenced during the later rather than the initial stages of projects and that H&S actions were significantly undertaken during stage 5. The frequency of H&S actions varied with each stakeholder dependent on the stage in which they were involved in. Recommendations were for H&S to be integrated in the initial stages of projects and for a follow up research to be conducted to investigate if there are improvements during the six project stages after full implementation of the Construction Regulations 2014. This requirement will force industry to comply and most importantly to drive joint efforts by the various stakeholders.
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- Date Issued: 2018
The impact, on fibre quality, of changing from conventional cotton to genetically modified cotton
- Authors: van Rensburg, Joané Jansen
- Date: 2018
- Subjects: Cotton -- Genetic engineering , Cotton -- Quality Cotton
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30408 , vital:30940
- Description: This study was aimed at investigating the impact, on cotton fibre quality, of changing from conventional (non-GM) to genetically modified (GM) cotton, in both South Africa and the United States of America (USA). The cotton quality data, pre- and post-GM, generated by Cotton SA and the USDA, respectively, using the HVI systems, were accessed for 25 years in South Africa, and 27 years in the U.S. The key cotton quality parameters evaluated were staple length, micronaire and strength. These quality parameters had been measured on the Uster® HVI system by the various classing facilities in South Africa and the USA, on each bale of cotton produced within the specific country. The data for South Africa covered the period from 1992 (six years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2007. Data for the USA covered the period from 1990 (five years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2010. The data accessed and compiled, from the respective databases of two different countries, had to be electronically captured, regrouped (according to standards provided by the USDA) and thereafter analysed. It was found that the introduction and phasing in of GM cotton in both South Africa and the USA had a beneficial impact on the overall quality (FQI) of cotton produced in these countries. These positive trends in FQI were mainly caused by an increase in staple length for both countries, due to the beneficial impact that the introduction and phasing in of GM cotton had on staple length. Certain of the fibre parameters, notably micronaire, tended to fluctuate from year to year, quite unrelated to the introduction and phasing in of GM cotton, this being ascribed to fluctuating climatic conditions, and the parameter’s extreme sensitivity to such conditions. Over the period covered, cotton fibre, strength, showed a different trend for each country, remaining largely constant in South Africa, while increasing in the USA, this being unrelated to the introduction of GM cotton per sé.
- Full Text:
- Date Issued: 2018
The implementation of a push-pull programme for the control of Eldana saccharina (Lepidoptera: Pyralidae) in sugarcane in the coastal regions of Kwazulu-Natal, South Africa
- Authors: Mulcahy, Megan Marie
- Date: 2018
- Subjects: Pyralidae -- South Africa -- KwaZulu-Natal , Pests -- Integrated control , Sugarcane -- Diseases and pests -- South Africa -- KwaZulu-Natal , Stem borers -- Effect of habitat modification on -- South Africa -- KwaZulu-Natal , Insect-plant relationships -- South Africa -- KwaZulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63290 , vital:28390
- Description: Eldana saccharina, an indigenous lepidopteran stemborer, is considered the most damaging pest of sugarcane in South Africa. Researchers have advocated the use of an area-wide integrated pest management (AW-IPM) programme as a means of improving the control of this pest. A push-pull strategy was developed as a component of this AW-IPM approach. The push-pull strategy in sugarcane is a habitat management method of pest control that uses plants that are both repellent (Melinis Minutiflora) and attractive (Cyperus dives, Cyperus papyrus and Bt-maize) to E. saccharina. Previous research into push-pull has shown that this strategy is an effective tool for the control of E. saccharina. Push-pull has been implemented successfully in the Midlands North sugarcane growing region of KwaZulu-Natal (KZN), South Africa. Despite the proven efficacy of push-pull, very little push-pull research has been conducted in the coastal sugarcane growing regions of KZN, and adoption of this technology has been poor in these regions. Therefore, the aim of this research was to facilitate the implementation of push-pull for the management of E. saccharina in sugarcane in the coastal regions of KZN. This was done by focussing on on-farm field trials and farmer participatory research. On-farm push-pull field trials were conducted on five model farms in the North and South Coast sugarcane growing regions of KZN. High levels of E. saccharina were recorded during this study. The push-pull treatment sites showed a significant reduction of E. saccharina damage on four of the five farms used in the study. Mean percentage of stalks damaged decreased by up to 50 % in the presence of the repellent grass species, M. minutiflora. The number of E. saccharina found per 100 stalks also decreased significantly at these farms. The farm which did not show a significant reduction in E. saccharina populations or damage had low numbers of this pest in the sugarcane throughout the experiment. This demonstrates that push-pull is more effective in areas that have high levels of E. saccharina. Stem borer surveys in wetlands on sugarcane farms revealed that high numbers of E. saccharina were found within the pull plants, C. papyrus and C. dives, in comparison to the push-pull sites. This verifies that the pull plants do work efficiently to attract E. saccharina away from sugarcane. Additionally, eight parasitoids emerged from E. saccharina larvae collected in wetland sedges. The beneficial roles that push-pull plants play in attracting and maintaining natural enemies in the agroecosystem are discussed, and these findings further demonstrate the important ecosystem, and pest management services that wetlands provide on sugarcane farms. The success of the push-pull trials in this study show that this technology can be an effective tool for controlling E. saccharina in the coastal sugarcane growing regions. The timing of the planting of push-pull plants was shown to play a role in the efficacy of this technology. The study also confirmed that push-pull should be used as a component of AW-IPM in conjunction with good crop management practices. Surveys were undertaken to determine large-scale sugarcane growers' (LSGs) knowledge and perceptions of E. saccharina and other pests. Research regarding the farmers' perceptions of push- pull was also conducted to better understand the drivers and barriers to adoption of push-pull, and other new technologies. The surveys found that large-scale farmers in the coastal regions suffer from high infestations of E. saccharina. As such there is scope for the introduction of new pest management practices such as push-pull in this area. Farmers also demonstrated a good basic knowledge of E. saccharina and IPM. However, LSGs had a poor understanding of push-pull and how it works, as well as the plants that make up the push-pull system that is being implemented against E. saccharina in South Africa. A dearth in practical knowledge regarding the implementation of push-pull was seen as a major barrier to the adoption of this strategy, as was financial instability, farmer attitudes and poor institutional support. Farmers recommended collaboration amongst stakeholders, improved education, proof of the efficacy of push-pull and incentives as tools to improve the implementation of this strategy in the coastal sugarcane growing regions of KZN. Farmers preferred direct contact with extension personnel and experiential learning opportunities when acquiring information about push- pull and other new pest management practices. If opportunities for push-pull education are increased through direct contact with extension personnel, and through on-farm demonstrations, and if inputs are provided in the form of push-pull plants, it is likely that push-pull will succeed amongst coastal LSGs, especially since farmers had an overall positive attitude towards the technology. Surveys amongst small-scale sugarcane growers (SSGs) showed that sugarcane is important in the lives of these farmers. The SSGs perceive pests to be a major constraint to their farming systems, and they identified E. saccharina as a major pest of sugarcane. The farmers also demonstrated good knowledge of sugarcane pests and vegetable pests. However, SSGs lacked knowledge regarding pest management practices and beneficial insects. Extension and advisory services should to continue concentrating on pest management practices to educate SSGs on the variety and application of pest control strategies. SSGs were found to employ complex, diverse and integrated agricultural systems that are well-suited to the implementation of IPM technologies such as push-pull. Since insect pests act were found to be a major constraint to SSG sugarcane production, push-pull was deemed a feasible pest management strategy for coastal farmers and its implementation by SSGs should be further explored. SSGs in this study were also concerned about vegetable pests, therefore if push-pull can be adapted to help protect additional crops, adoption of this technology by small-scale growers will improve.
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- Date Issued: 2018
The implications of utilising small, medium and micro sized enterprises on construction projects
- Authors: Kampman, Juan
- Date: 2018
- Subjects: Small business -- South Africa , Construction industry -- Management Construction industry -- Economic aspects Construction industry -- Cost effectiveness
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30698 , vital:31031
- Description: The National Development Plan envisages that eleven million jobs will be created in South Africa by small and medium enterprises (SME) by 2030. This vehicle aims to generate employment opportunities, redistribute income and contribute to poverty alleviation. This research highlights the main hurdles associated with the appointment of small, medium and micro-enterprise (SMME) contractors while providing recommendations geared towards the development of a sustainable industry. This study focuses on the cost, quality, programme, and health and safety implications of utilising SMMEs on construction projects. The study is seen from the perspective of the client’s representatives on construction projects and it focuses on South African National Roads Agency Limited (SANRAL) projects in the Eastern Cape. The respondents answered a structured web-based questionnaire which included open and closed questions. The research determined that in order to provide the best quality work, at the best price, on time, and in a safe manner, SMMEs who are employed on construction projects should be experienced or should be trained and mentored, or both. To ensure that SMMEs function at the required level with regard to the cost of their service, the quality of work, construction duration, and health and safety, it is fundamental to train and mentor the SMMEs. In order to assist SMMEs, they should be supported by providing construction material, the required tools, and personal protective equipment at the start of a project. It was proposed that SMME guidelines be drafted in order to standardise implementation methodologies which can be applied throughout the construction industry.
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- Date Issued: 2018
The influence of construction project managers’ experience on project performance: the case of Nelson Mandela Bay infrastructure projects
- Authors: Parazee, Viahn
- Date: 2018
- Subjects: Infrastructure (Economics) -- South Africa -- Nelson Mandela Bay Municipality , Economic development projects -- South Africa -- Nelson Mandela Bay Municipality -- Management Public works -- South Africa -- Nelson Mandela Bay Municipality -- Management Project Management -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34510 , vital:33387
- Description: When you start out in the engineering industry especially in the public sector, one seldom has the mentorship required to equip you with the skills to succeed in successfully implementing projects. It has furthermore been observed that there is a major difference between project management competencies and merely having a qualification in the same field as the project’s core business. The role of Construction Project Managers is especially unique within public sector projects as these projects often involve multiple stakeholders whose opinions can strongly influence the project(Jalocha et al., 2014). This has been the case within the Nelson Mandela Bay Municipality where labour and community unrest often result in project stoppages and delays which ultimately lead to project failure. Stakeholder engagement, an inherently social competence, is a key component of Project Management Competence and falls outside the curriculum of most technical qualifications in the built environment. Project Management failure within the public sector has become rife and the research findings of this study should be helpful in assisting the local government in attaining higher project success rates. A qualitative research approach was adopted for this study making use of a descriptive research design, yielding qualitative data which was summarised by the researcher through statistical analyses. The data were obtained through questionnaires distributed to the various Clients, Consultants and Contractors within the NMBM via email. The questionnaires were furthermore only distributed to government parastatals within the construction industry in the NMBM, Consultants and Contractors who have completed or are working on projects for these parastatals within the public sector. Key findings from the research note a positive relationship between competency and project success; that there is not enough mentorship received by Construction Project Managers in the built environment sectors; that there is a positive relationship between mentorship received and project success and that there is a significant difference in the number of professionally registered personnel in the Consulting Sector compared to that of the Public-Sector. It furthermore indicated that there was a positive correlation between supervisors being professionally registered and their junior Construction Project Managers achieving project success from the research findings, recommendations were made to aid the increase in project success rates and decrease project management failure within the NMBM. For this to be achieved, the following areas need to be addressed: Assigning of projects to Construction Project Managers, Mentorship provided to Construction Project Managers and ultimately their Project Management Competence.
- Full Text:
- Date Issued: 2018
The influence of landscape dis-connectivity on the structure and function of the Krom River, Eastern Cape, South Africa
- Authors: McNamara, Shaun
- Date: 2018
- Subjects: Wetland ecology -- South Africa -- Kromme River (Eastern Cape) , Alluvial fans -- South Africa -- Kromme River (Eastern Cape) , Sedimentation and deposition -- South Africa -- Kromme River (Eastern Cape) , Fluvial geomorphology -- South Africa -- Kromme River (Eastern Cape) , Soil erosion -- South Africa -- Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63198 , vital:28380
- Description: Given that a broad valley and low longitudinal slope are important pre-requisites for wetland formation in dryland environments, it has been proposed that cut-and-fill cycles are largely responsible for the geomorphic evolution of the Krom River valley-bottom wetlands. Research to support this suggestion has focused extensively on the role of phases of incision. As a result, little is known about where sediment mobilised during phases of incision is being deposited (filling phase). This study aimed to address this question to add to the understanding of how cut-and-fill cycles influence the structure and functioning of the Krom River and its wetlands. This was achieved through a reach-scale appraisal of the degree of longitudinal connectivity of the Krom River. The reach used for this appraisal contained an incised section along which the river channel exists as a large gully, and a section immediately downstream of the gully terminus where the Krom River is un-gullied, and flow is diffuse across most of the width of the valley floor. Quantification of the masses of sediment eroded and deposited within the selected reach of the Krom River during a single recent (2012) flood event revealed that the degree of longitudinal connectivity in the Krom River is generally low. During the flood, much of the sediment mobilised by the cutting of the Krom River channel was deposited immediately downstream of the gully terminus, forming a large floodout feature. Particle size analyses of core samples taken along the floodout feature showed that the coarsest fraction of previously mobilised sediment was deposited at the head of the floodout, while finer sediment fractions were deposited progressively further downstream. Field surveys revealed that the pattern of deposition within the floodout feature led to localised steepening of the studied reach of the Krom River downstream of the gully terminus. Surveys of the recently eroded gully revealed that following incision, the eroded stream bed had a lower longitudinal gradient than both the pre-erosional land surface and the regional slope of the Krom River. The results of this study suggest that floodout formation downstream of gullies may promote the transgression of geomorphic thresholds for erosion, such that the development of floodout features leads to likely initiation of new cutting phases in novel locations along the course of the Krom River. They further suggest that the Krom River is capable of intrinsic longitudinal self-recovery through ongoing cut-and-fill cycles. Finally, it would appear that the current cutting phases responsible for the “destruction” of wetlands within the system are part of a cycle that will lead to prolonged geomorphic stability, such that the system is made more suitable for the long-term re-establishment of wetlands.
- Full Text:
- Date Issued: 2018
The metabolic physiology of early stage Argyrosomus japonicus with insight into the potential effects of pCO2 induced ocean acidification
- Authors: Edworthy, Carla
- Date: 2018
- Subjects: Argyrosomus , Argyrosomus -- Growth , Argyrosomus -- Mortality , Argyrosomus -- Larvae -- Ecology , Ocean acidification , Marine ecology -- South Africa , Carbon dioxide -- Physiological effect
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/51417 , vital:26094
- Description: Ocean acidification is a phenomenon associated with global change and anthropogenic CO2 emissions that is changing the chemistry of seawater. These changes result in elevated pCO2 and reduced pH in seawater and this is impacting marine organisms in various ways. Marine fishes are considered generally tolerant to conditions of ocean acidification; however, these assumptions are based on juvenile and adult fish tolerance and the larval stages have not been frequently assessed. Furthermore, it has been suggested that temperate species, particularly those with an estuarine association, may be tolerant to variable CO2 and pH. This study used an eco-physiological approach to understand how the early life stages of Argyrosomus japonicus, an estuarine dependent marine fisheries species found in warm-temperate regions, may be impacted by ocean acidification. The metabolic response of early stage larvae (hatching to early juvenile stage) was assessed under conditions of elevated pCO2 and reduced pH in a controlled laboratory setting. Small volume static respirometry was used to determine the oxygen consumption rate of larvae raised in three pCO2 treatments including a low (pCO2 = 327.50 ± 80.07 µatm at pH 8.15), moderate (pCO2 477.40 ± 59.46 µatm at pH 8.03) and high treatment (PCO2 910.20 ± 136.45 µatm at pH 7.78). These treatment levels were relevant to the present (low) and projected conditions of ocean acidification for the years 2050 (moderate) and 2100 (high). Prior to experimentation with ocean acidification treatments, baseline metabolic rates and diurnal variation in oxygen consumption rates in early stage A. japonicus was determined. Distinct ontogenetic structuring of metabolic rates was observed in early stage A. japonicus, with no cyclical fluctuations in metabolic rate occurring during the 24 hour photoperiodic cycle. Pre-flexion larvae showed no metabolic response to ocean acidification treatments; however post-flexion stage larvae showed metabolic depression of standard metabolic rate in the moderate (32.5%) and high (9.5%) pCO2 treatments (P = 0.02). Larvae raised in the high pCO2 treatment also showed high levels of mortality with no individuals surviving past the post-flexion stage. Larvae raised in the moderate pCO2 treatment were unaffected. This study concluded that ocean acidification conditions expected for the end of the century will have significant impacts on the metabolism of early stage A. japonicus, which may result in reduced growth, retardation of skeletal development and ultimately survival as a result of increased mortality. Furthermore, the timing of reduced metabolic scope will significantly impact the recruitment ability of A. japonicus larvae into estuarine habitats. This could ultimately impact the sustainability of A. japonicus populations. Most importantly, this study highlighted the need to consider the combined effect of ontogeny and life-history strategy when assessing the vulnerability of species to ocean acidification.
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- Date Issued: 2018
The potential significance of refugia in safeguarding Non-Timber Forest products under Harvesting
- Authors: Mjoli, Nwabisa
- Date: 2018
- Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Nature conservation -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60596 , vital:27801
- Description: Many rural households living in and adjacent to forests in South Africa harvest a variety of NonTimber Forest Products (NTFPs) such as wild fruits, fibre, fuelwood, seeds, medicine and bush meat for domestic use, sale and maintaining cultural values. To promote the continued availability of these NTFPs it is important that NTFPs are well maintained and that harvest offtake is sustainable, because if it is not, then the important livelihood function that they fulfil will be jeopardized over time. The role of refugia in conserving pockets of threatened species from overharvesting has rarely been considered. Building on Shackleton et al. (2015), six applications of the concept are considered: size refugia, spatial refugia, cultural/spiritual refugia and physical/habitat refugia. I examined the prevalence and type of refugia for NTFPs at three coastal sites in the Eastern Cape province of South Africa. This was done via several community focus group discussions at each site. Here I report on the role of refugia in offering some safeguard to NTFPs by assessing harvested and non-harvested sites of refugia as well as individual plant species by measuring population density, harvest damage and size class profile. Respondents from the focus group discussions perceived a general decline in the abundance of common, widely used species over the past five decades. Decreasing rainfall and distant farming activities was reported consistently by the majority of the respondents. The most common form of refugia was spatial refugia, followed by cultural/spiritual refugia and physical/habitat refugia. Only six species were identified to be in refugia, namely Cyperus congestus, Cyperus textillis, Millettia grandis, Olea europaea subsp. africana, Phoenix reclinata, and Ptaeroxylon obliquum. Population inventories revealed that regeneration and population densities of some NTFP species in the non-refuge site were adversely affected by harvesting. Populations in refuge sites generally had the largest size classes indicating a regeneration potential but likely to impact regeneration over time if pressures are maintained. Therefore, if refuge sites keep larger individuals, NTFP populations can be maintained. Few studies have critically analyzed the concept of refugia in relation to how NTFPs can be safeguarded and the practical implication of the refuge concept needs to be considered in conservation and strategies and population models.
- Full Text:
- Date Issued: 2018