The extent of urban Green Collar employment, its contribution to poverty alleviation and potential for growth in the Eastern Cape, South Africa
- Authors: King, Andrew
- Date: 2019
- Subjects: Economic development -- Environmental aspects -- South Africa -- Eastern Cape , Poverty prevention -- South Africa -- Eastern Cape , Job creation -- South Africa -- Eastern Cape , Urban ecology (Sociology) -- South Africa -- Eastern Cape , Urban poor -- Employment -- South Africa -- Eastern Cape , Clean energy industries -- Employment -- South Africa -- Eastern Cape , Renewable energy sources -- Government policy -- South Africa -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Open spaces -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115191 , vital:34095
- Description: The aim of this research was to investigate the job provisioning benefits of urban green space (GS), the ability of these jobs to alleviate poverty amongst poor urban households, as well as the potential to increase the number of Green Collar (GC) jobs. According to Lal et al. (2010), Roy et al. (2012) and others, environmental employment or GC jobs, represent the very synergy between social, economic and environmental resilience and sustainability, and have the ability to provide an additional range of goods and services. Data was collected from 12 towns and cities in the Eastern Cape of South Africa, all varying in population, town size and geographic location. Structured employer, employee and resident interviews were used to collect data, which pertained to a number of employment characteristics and employee living conditions. Throughout the sample, 19 different types of jobs were identified, and a total of 17 429 GC employees were counted, sharing a total of approximately R503 million in annual wages. Some GC employees were found to still be in a position of poverty despite employment, while others enjoyed a higher standard of living as a result, although this was largely dependent on the extent of wages and other household and employment attributes. Using lessons learnt from previous chapters, a number of data sources and a creative approach, the potential for growth and improvement in the urban GC sector was discussed, and the way forward involves private, public, informal and civil sector participation and innovation; which will not only enhance environmental and social ecosystem services, but also provide meaningful employment opportunities to the otherwise impoverished. Urban GC jobs should be widely viewed as a useful tool in achieving social, environmental and economic prosperity in urban landscapes (Bowen and Kuralbayeva, 2015).
- Full Text:
- Date Issued: 2019
- Authors: King, Andrew
- Date: 2019
- Subjects: Economic development -- Environmental aspects -- South Africa -- Eastern Cape , Poverty prevention -- South Africa -- Eastern Cape , Job creation -- South Africa -- Eastern Cape , Urban ecology (Sociology) -- South Africa -- Eastern Cape , Urban poor -- Employment -- South Africa -- Eastern Cape , Clean energy industries -- Employment -- South Africa -- Eastern Cape , Renewable energy sources -- Government policy -- South Africa -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Open spaces -- Environmental aspects -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115191 , vital:34095
- Description: The aim of this research was to investigate the job provisioning benefits of urban green space (GS), the ability of these jobs to alleviate poverty amongst poor urban households, as well as the potential to increase the number of Green Collar (GC) jobs. According to Lal et al. (2010), Roy et al. (2012) and others, environmental employment or GC jobs, represent the very synergy between social, economic and environmental resilience and sustainability, and have the ability to provide an additional range of goods and services. Data was collected from 12 towns and cities in the Eastern Cape of South Africa, all varying in population, town size and geographic location. Structured employer, employee and resident interviews were used to collect data, which pertained to a number of employment characteristics and employee living conditions. Throughout the sample, 19 different types of jobs were identified, and a total of 17 429 GC employees were counted, sharing a total of approximately R503 million in annual wages. Some GC employees were found to still be in a position of poverty despite employment, while others enjoyed a higher standard of living as a result, although this was largely dependent on the extent of wages and other household and employment attributes. Using lessons learnt from previous chapters, a number of data sources and a creative approach, the potential for growth and improvement in the urban GC sector was discussed, and the way forward involves private, public, informal and civil sector participation and innovation; which will not only enhance environmental and social ecosystem services, but also provide meaningful employment opportunities to the otherwise impoverished. Urban GC jobs should be widely viewed as a useful tool in achieving social, environmental and economic prosperity in urban landscapes (Bowen and Kuralbayeva, 2015).
- Full Text:
- Date Issued: 2019
The impact of elephants on thicket vegetation and other mammals in the Eastern Cape Province, South Africa
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
The influence of artificial light on the foraging efficiency and diet of insect eating bats
- Authors: Bailey, Lauren
- Date: 2019
- Subjects: Predation (Biology) , Bats -- Effect of light on , Bats -- Nutrition , Moths
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76376 , vital:30555
- Description: Artificial light may be altering the interactions between bats and moth prey. Unable to make use of bat evasion strategies around artificial light, eared moths are susceptible to exploitation by syntonic bats (using echolocation frequencies between 20-50 kHz within the hearing range of eared moths). Using a handheld plasma metabolite analyzer, I evaluated the foraging success of syntonic bats and rarer allotonic bats (using echolocation frequencies outside the hearing range of eared moths), in areas with artificial light and in areas of natural darkness. I used microscope diet analysis to determine whether bats were consuming more or fewer moths in areas with artificial light and in areas of natural darkness. Syntonic bats were more selective for moth prey under lit conditions, likely owing to a reduction in the ability of tympanate moths to evade bats. Moths increased in the diets of generalist syntonic bats (Pipistrellus hesperidus) foraging around artificial light sources. Some P. hesperidus individuals showed high β-hydroxybutyrate levels around lights, but there was no difference in β-hydroxybutyrate levels between lit and unlit conditions. There is insufficient evidence to reject the null hypothesis that the foraging success of syntonic bats is equivalent in lit vs unlit conditions. The foraging success and diets of allotonic bats, Rhinolophus capensis, appear to be negligibly impacted by artificial light on a small scale. My study emphasizes the need for a mechanistic understanding of the influence of artificial light on the foraging success of bat species. Bat-moth interactions may be influenced by other factors apart from the common assumption that increased refuelling rates will occur in syntonic species foraging on moths around artificial light.
- Full Text:
- Date Issued: 2019
- Authors: Bailey, Lauren
- Date: 2019
- Subjects: Predation (Biology) , Bats -- Effect of light on , Bats -- Nutrition , Moths
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76376 , vital:30555
- Description: Artificial light may be altering the interactions between bats and moth prey. Unable to make use of bat evasion strategies around artificial light, eared moths are susceptible to exploitation by syntonic bats (using echolocation frequencies between 20-50 kHz within the hearing range of eared moths). Using a handheld plasma metabolite analyzer, I evaluated the foraging success of syntonic bats and rarer allotonic bats (using echolocation frequencies outside the hearing range of eared moths), in areas with artificial light and in areas of natural darkness. I used microscope diet analysis to determine whether bats were consuming more or fewer moths in areas with artificial light and in areas of natural darkness. Syntonic bats were more selective for moth prey under lit conditions, likely owing to a reduction in the ability of tympanate moths to evade bats. Moths increased in the diets of generalist syntonic bats (Pipistrellus hesperidus) foraging around artificial light sources. Some P. hesperidus individuals showed high β-hydroxybutyrate levels around lights, but there was no difference in β-hydroxybutyrate levels between lit and unlit conditions. There is insufficient evidence to reject the null hypothesis that the foraging success of syntonic bats is equivalent in lit vs unlit conditions. The foraging success and diets of allotonic bats, Rhinolophus capensis, appear to be negligibly impacted by artificial light on a small scale. My study emphasizes the need for a mechanistic understanding of the influence of artificial light on the foraging success of bat species. Bat-moth interactions may be influenced by other factors apart from the common assumption that increased refuelling rates will occur in syntonic species foraging on moths around artificial light.
- Full Text:
- Date Issued: 2019
The integration of effluent treatment using constructed wetlands, with crop production and aquaculture
- Authors: de Jong, Martyn
- Date: 2019
- Subjects: Recycling (Waste, etc.) , Brewery waste , Sewage -- Purification , Beets , Mozambique tilapia
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95767 , vital:31197
- Description: Breweries are major consumers of water and produce nutrient rich wastewater. Therefore, it is important to research technologies that optimise the reuse and recycling of this waste. This study compared different constructed wetlands (CWs) in terms of their potential for cleaning brewery effluent and simultaneously producing crops Beta vulgaris and fish Oreochromis mossambicus. Filling and draining times (FDT; 15 min, 30 min and 60 min) in tidal CWs were compared in Experiment 1. The 15 min FDT (6.52 ± 0.09 mg/l) and 30 min FDT (5.74 ± 0.09 mg/l) had higher dissolved oxygen (DO) than the 60 min FDT (5.40 ± 0.09 mg/l; p<0.05). This resulted in the 15 and 30 min FDT treatments reaching ammonia effluent discharge standards sooner than the 60 min FDT. Total plant harvest increased with increasing FDT; therefore, 15 min FDT was used as the FDT in tidal treatments in the following experiments. The aerated CW (5.81 ± 0.07 mg/l) and tidal CW (5.67 ± 0.07 mg/l) treatments had higher DO concentrations than the unaerated CW treatment (3.76 ± 0.07 mg/l; p<0.05) in Experiment 2. This resulted in lower ammonia concentrations on day 5 in the aerated and tidal CWs compared with the unaerated treatment (p<0.05). The tidal CW (23.97 ± 2.57 kg) had a total harvest that was approximately four times higher than the unaerated CW (p<0.05), which had the highest frequency of chlorosis and plant mortality; and was unable to treat ammonia to discharge standards. In Experiment 3, the aerated and tidal CW were compared with municipal-water as water sources for aquaculture. There were no differences in fish growth (p > 0.05). However, there were differences in water quality; with the municipal treatment having the lowest pH, EC and nitrate concentration (p<0.05); but all water quality parameters remained in a range suitably for fish production. Due to the tidal CW having the highest plant harvest and lowest frequency of chlorosis and mortality; it was the most suitable CW technology to clean the brewery effluent, and to produce B. vulgaris and water that could be used downstream in aquaculture.
- Full Text:
- Date Issued: 2019
- Authors: de Jong, Martyn
- Date: 2019
- Subjects: Recycling (Waste, etc.) , Brewery waste , Sewage -- Purification , Beets , Mozambique tilapia
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95767 , vital:31197
- Description: Breweries are major consumers of water and produce nutrient rich wastewater. Therefore, it is important to research technologies that optimise the reuse and recycling of this waste. This study compared different constructed wetlands (CWs) in terms of their potential for cleaning brewery effluent and simultaneously producing crops Beta vulgaris and fish Oreochromis mossambicus. Filling and draining times (FDT; 15 min, 30 min and 60 min) in tidal CWs were compared in Experiment 1. The 15 min FDT (6.52 ± 0.09 mg/l) and 30 min FDT (5.74 ± 0.09 mg/l) had higher dissolved oxygen (DO) than the 60 min FDT (5.40 ± 0.09 mg/l; p<0.05). This resulted in the 15 and 30 min FDT treatments reaching ammonia effluent discharge standards sooner than the 60 min FDT. Total plant harvest increased with increasing FDT; therefore, 15 min FDT was used as the FDT in tidal treatments in the following experiments. The aerated CW (5.81 ± 0.07 mg/l) and tidal CW (5.67 ± 0.07 mg/l) treatments had higher DO concentrations than the unaerated CW treatment (3.76 ± 0.07 mg/l; p<0.05) in Experiment 2. This resulted in lower ammonia concentrations on day 5 in the aerated and tidal CWs compared with the unaerated treatment (p<0.05). The tidal CW (23.97 ± 2.57 kg) had a total harvest that was approximately four times higher than the unaerated CW (p<0.05), which had the highest frequency of chlorosis and plant mortality; and was unable to treat ammonia to discharge standards. In Experiment 3, the aerated and tidal CW were compared with municipal-water as water sources for aquaculture. There were no differences in fish growth (p > 0.05). However, there were differences in water quality; with the municipal treatment having the lowest pH, EC and nitrate concentration (p<0.05); but all water quality parameters remained in a range suitably for fish production. Due to the tidal CW having the highest plant harvest and lowest frequency of chlorosis and mortality; it was the most suitable CW technology to clean the brewery effluent, and to produce B. vulgaris and water that could be used downstream in aquaculture.
- Full Text:
- Date Issued: 2019
The invasion ecology of Nymphaea mexicana Zucc. (Mexican Water lily) in South Africa
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
- Authors: Naidu, Prinavin
- Date: 2019
- Subjects: Nymphaea Mexicana zuccarini , Nymphaea , Nymphaea -- Biological control -- South Africa , Water lilies , Nymphaea -- Ecology -- South Africa , Water lilies -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water lilies -- Ecology -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92920 , vital:30763
- Description: The Mexican water lily, Nymphaea mexicana Zuccarini, is an aquatic perennial, native to southern USA and Mexico, and has been introduced to South Africa via the ornamental plant trade. This species has rapid growth rates and becomes weedy in dams, ponds and rivers. It is currently listed as a NEM:BA category 1b invasive plant in South Africa. One possible management measure for this weed is biological control, but it is a novel target because no biological control programme has been initiated against it anywhere in the world. This study is intended as a baseline for the biological control programme against this plant in South Africa. Assessing the population structure and mode of reproduction of invasive alien plants is an imperative aid to determining if biological control is a suitable management option. Using amplified fragment length polymorphism (AFLP) molecular markers, I compared the amount of genetic variability and differentiation of N. mexicana in its native range (USA), and invasive range (South Africa). Results indicated a large genetic distance between populations in the USA and South Africa, compared to populations within each country. The genetic variability of the invasive populations was higher than that found in the native distribution. This could be due to hybridization in the introduced range, and/or multiple introductions from different source populations. Differences in the morphology of N. mexicana plants in the invasive range and South Africa were also observed which confirm the results of the genetic analyses. I also assessed the reproductive mode of N. mexicana cultivars/hybrids by conducting breeding system experiments and field pollinator studies. Results indicated that the cultivars are sterile, suggesting that the primary mode of reproduction is asexual via fragmentation of tubers. The main pollinators that were found to be associated with the cultivars in South Africa were honeybees, sweat bees, flies and beetles. These insect groups were the same as those that were observed in another study which was conducted on the pollinators associated with the pure N. mexicana in the native range in southern USA. Mechanical and chemical control of N. mexicana and its multiple genotypes have been applied but have not been efficient due to the fast regeneration of shoots, especially in summer. Therefore, these two management options are not long–term solutions and will also be costly due to the widespread occurrence of the hybrids in South Africa. Thus the only cost–effective, environmentally friendly, self–sustainable and long–term management option is biological control. The significant divergence between native and invasive populations of N. mexicana, as well as the possibility of numerous invasive cultivars, may limit future prospects of biological control of this species. However the differences in the root structures between native South African waterlilies, such as N. lotus and N. nouchali, and the introduced waterlilies, such as N. mexicana and its associated hybrids, may play a pivotal role in the success of biological control of the N. mexicana hybrid complex in South Africa. Natural enemies which feed on the hard tuberous roots of N. mexicana and its hybrids, as opposed to the soft bulbs of the native N. nouchali and N. lotus, should be prioritised.
- Full Text:
- Date Issued: 2019
The morphological and molecular variation of southern African Nannocharax (Characiformes: Distichodontidae), and its taxonomic implications
- Authors: Smith, Timothy
- Date: 2019
- Subjects: Nannocharax -- Africa, Southern , Distichodontidae -- Africa, Southern , Freshwater fishes -- Africa, Southern , Nannocharax -- Genetics -- Africa, Southern , Distichodontidae -- Genetics -- Africa, Southern , Freshwater fishes -- Genetics -- Africa, Southern
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69212 , vital:29446
- Description: Nannocharax is the most species rich genus in the family Distichodontidae, being currently represented by 41 species. The genus is widely distributed across much of sub-Saharan Africa, with a range extending from the Zambezi ichthyofaunal province in the south to the Nilo-Sudan ichthyofaunal province in the north. In southern Africa, the genus is currently represented by four species, Nannocharax dageti Jerep, Vari, & Vreven, 2014, N. machadoi (Poll, 1967), N. macropterus Pellegrin, 1926, and N. multifasciatus Boulenger, 1923. Each of these species exhibit considerable intraspecific pigmentation pattern variation across their respective distribution ranges, suggesting that the current taxonomy possibly underestimates the taxonomic diversity of Nannocharax species in southern Africa. Much pigmentation pattern variation within these southern African species has been observed by both collectors and scientists in the field, prompting an investigation into the extent of this morphological variation as well as what molecular variation may occur as well. The genus displays a high degree of morphological conservatisim, making it difficult to assign external morphological characters as diagnostic. To this end, this study was conducted to determine the extent of diversity of this genus in the region, employing an integrative approach with traditional morphological analysis techniques as well as sequencing the ‘barcoding gene’, cytochrome oxidase I, testing the hypothesis that there is a greater, hidden diversity of this genus in the region than currently recognised. This study aims to identify these potential lineages and accurately map their distributions. Phylogenetic analyses were performed using maximum parsimony, maximum likelihood, and Bayesian inference, using the mitochondrial cytochrome oxidase I gene region. Massive genetic divergence was detected between populations of taxa previously considered to be singular, widely distributed species. The three approaches of phylogenetic inference used in this study yielded trees of comparable overall topology, with the exception of the maximum parsimony tree which indicated additional lineages within the southern African N. multifasciatus group. These analyses revealed four deeply divergent (1.3 – 12.3%) lineages within southern African N. macropterus, as well as two deeply divergent (0.4-14.6%) populations from the Congo ichthyofaunal region, the lineages here named “N. macropterus Congo 1” and “N. macropterus Congo 2”. Within the southern African region, two deeply divergent (10.3%) lineages of N. macropterus were identified from the Okavango River system, identified as “N. macropterus Okavango 2” lineage restricted to the Cuito-Canavale tributary, and “N. macropterus Okavango 1” distributed throughout the remainder of the Okavango system. “N. macropterus Okavango 2” shares a closer relationship with the unique lineage from the Kwanza ichthyofaunal region, named N. macropterus “Kwanza”, which itself is deeply divergent from the N. macropterus “Okavango 1”, N. macropterus “Zambezi”, N. macropterus “Congo 1” and N. macropterus “Congo 2” lineages (3.1-14.4%). Principal component analyses (PCA) and discriminant function analyses (DFA) produced overlapping clusters for all identified lineages, with the exception of the N. macropterus “Kwanza” lineage, which in all analyses clustered away from the other lineages. Analysis of variance (ANOVA) and Kruskall-Wallis tests indicated significant differences in means between character traits between lineages, however, overlap in measurements and counts occurred in all instances except between the N. macropterus “Kwanza” and N. macropterus Congo lineages. However the N. macropterus “Kwanza” lineages could be distinguished from the other lineages by generally smaller fin lengths (dorsal fin 19.5%SL vs 20.0-22.1%SL in others; pectoral fin 16.5%SL vs 20.6-21.8%SL in others; pelvic fin 18.3%SL vs 21.3-22.4) and pigmentation pattern differences. The N. macropterus species group displayed extensive pigmentation pattern variation, to the extent that five pattern grades could be used to classify them. These pattern grades, while not specific to river systems, showed patterns similar to that which was seen in the molecular analyses and could be linked to lineages with only minor overlap between them. Three lineages of N. multifasciatus were identified, with two occurring in the southern African region, each corresponding to a river system, being the N. multifasciatus “Zambezi” and N. multifasciatus “Okavango” lineages. This species group displayed shallower divergence between lineages than did the N. macropterus group, at 2.5% genetic distance. Genetic analysis inferred a closer relationship between the N. multifasciatus “Zambezi” and N. multifasciatus “Congo” lineages than with the N. multifasciatus “Okavango” lineage. Morphological PCA and DFA analyses indicated morphological divergence of the N. multifasciatus “Congo” lineage, with generally larger proportional measurements than southern African specimens (body width 12.6%SL vs 9.5-9.7%SL; body depth 26.6%SL vs 21.6-21.9%SL; head width 12.0%SL vs 10.0-10.4%SL). PCA, DFA, and measurements show a near complete overlap between the N. multifasciatus “Okavango” and N. multifasciatus “Zambezi” lineages. Pigmentation pattern variation occurred within this group, but none that could be assigned to a particular lineage. The N. machadoi species group in southern Africa consists of five lineages: N. machadoi “Zambezi 1”, N. machadoi “Zambezi 2”, N. machadoi “Kafue 1”, N. machadoi “Kafue 2”, and N. machadoi “Okavango”. This group displayed shallower genetic divergence between lineages than the other southern African Nannocharax species groups (0.4-1.3%). This shallow genetic divergence is paralleled by near complete morphological overlap, with PCA and DFA producing overlapping clusters, and measurements, meristics, and pigmentation pattern metrics consisting of very similar values for the lineages. These results indicate that what is considered to be “N. macropterus” in southern Africa should not be named as such. The N. macropterus “Zambezi” and the N. macropterus “Okavango 1” lineages, are misidentifications of Nannocharax dageti. Other “N. macropterus” from the southern African region possesses fewer circumpeduncular scales than the true N. macropterus as described by Pellegrin (1926), and require taxonomic re-evaluation, each here being recognised as a unique lineage with species status, here named N. macropterus “Okavango 2” and N. macropterus “Kwanza”. In particular, N. macropterus “Kwanza” displays deep genetic divergence as well as morphological dissimilarity with the other southern African “N. macropterus” groups. Nannocharax fasciolaris and N. monardi are here placed as junior synonyms of N. multifasciatus, owing to vast overlaps in measurements and character counts of these species and N. multifasciatus, which is also known to occur within the same geographical distribution, as well as dubious arguments from the original publications in delineating these species from N. multifasciatus. Therefore, there is insufficient evidence indicating the presence of multiple species originating from the Okavango system, where it is here indicated that only a single lineage of banded, adipose fin-bearing Nannocharax occurs, namely N. multifasciatus “Okavango”.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Timothy
- Date: 2019
- Subjects: Nannocharax -- Africa, Southern , Distichodontidae -- Africa, Southern , Freshwater fishes -- Africa, Southern , Nannocharax -- Genetics -- Africa, Southern , Distichodontidae -- Genetics -- Africa, Southern , Freshwater fishes -- Genetics -- Africa, Southern
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69212 , vital:29446
- Description: Nannocharax is the most species rich genus in the family Distichodontidae, being currently represented by 41 species. The genus is widely distributed across much of sub-Saharan Africa, with a range extending from the Zambezi ichthyofaunal province in the south to the Nilo-Sudan ichthyofaunal province in the north. In southern Africa, the genus is currently represented by four species, Nannocharax dageti Jerep, Vari, & Vreven, 2014, N. machadoi (Poll, 1967), N. macropterus Pellegrin, 1926, and N. multifasciatus Boulenger, 1923. Each of these species exhibit considerable intraspecific pigmentation pattern variation across their respective distribution ranges, suggesting that the current taxonomy possibly underestimates the taxonomic diversity of Nannocharax species in southern Africa. Much pigmentation pattern variation within these southern African species has been observed by both collectors and scientists in the field, prompting an investigation into the extent of this morphological variation as well as what molecular variation may occur as well. The genus displays a high degree of morphological conservatisim, making it difficult to assign external morphological characters as diagnostic. To this end, this study was conducted to determine the extent of diversity of this genus in the region, employing an integrative approach with traditional morphological analysis techniques as well as sequencing the ‘barcoding gene’, cytochrome oxidase I, testing the hypothesis that there is a greater, hidden diversity of this genus in the region than currently recognised. This study aims to identify these potential lineages and accurately map their distributions. Phylogenetic analyses were performed using maximum parsimony, maximum likelihood, and Bayesian inference, using the mitochondrial cytochrome oxidase I gene region. Massive genetic divergence was detected between populations of taxa previously considered to be singular, widely distributed species. The three approaches of phylogenetic inference used in this study yielded trees of comparable overall topology, with the exception of the maximum parsimony tree which indicated additional lineages within the southern African N. multifasciatus group. These analyses revealed four deeply divergent (1.3 – 12.3%) lineages within southern African N. macropterus, as well as two deeply divergent (0.4-14.6%) populations from the Congo ichthyofaunal region, the lineages here named “N. macropterus Congo 1” and “N. macropterus Congo 2”. Within the southern African region, two deeply divergent (10.3%) lineages of N. macropterus were identified from the Okavango River system, identified as “N. macropterus Okavango 2” lineage restricted to the Cuito-Canavale tributary, and “N. macropterus Okavango 1” distributed throughout the remainder of the Okavango system. “N. macropterus Okavango 2” shares a closer relationship with the unique lineage from the Kwanza ichthyofaunal region, named N. macropterus “Kwanza”, which itself is deeply divergent from the N. macropterus “Okavango 1”, N. macropterus “Zambezi”, N. macropterus “Congo 1” and N. macropterus “Congo 2” lineages (3.1-14.4%). Principal component analyses (PCA) and discriminant function analyses (DFA) produced overlapping clusters for all identified lineages, with the exception of the N. macropterus “Kwanza” lineage, which in all analyses clustered away from the other lineages. Analysis of variance (ANOVA) and Kruskall-Wallis tests indicated significant differences in means between character traits between lineages, however, overlap in measurements and counts occurred in all instances except between the N. macropterus “Kwanza” and N. macropterus Congo lineages. However the N. macropterus “Kwanza” lineages could be distinguished from the other lineages by generally smaller fin lengths (dorsal fin 19.5%SL vs 20.0-22.1%SL in others; pectoral fin 16.5%SL vs 20.6-21.8%SL in others; pelvic fin 18.3%SL vs 21.3-22.4) and pigmentation pattern differences. The N. macropterus species group displayed extensive pigmentation pattern variation, to the extent that five pattern grades could be used to classify them. These pattern grades, while not specific to river systems, showed patterns similar to that which was seen in the molecular analyses and could be linked to lineages with only minor overlap between them. Three lineages of N. multifasciatus were identified, with two occurring in the southern African region, each corresponding to a river system, being the N. multifasciatus “Zambezi” and N. multifasciatus “Okavango” lineages. This species group displayed shallower divergence between lineages than did the N. macropterus group, at 2.5% genetic distance. Genetic analysis inferred a closer relationship between the N. multifasciatus “Zambezi” and N. multifasciatus “Congo” lineages than with the N. multifasciatus “Okavango” lineage. Morphological PCA and DFA analyses indicated morphological divergence of the N. multifasciatus “Congo” lineage, with generally larger proportional measurements than southern African specimens (body width 12.6%SL vs 9.5-9.7%SL; body depth 26.6%SL vs 21.6-21.9%SL; head width 12.0%SL vs 10.0-10.4%SL). PCA, DFA, and measurements show a near complete overlap between the N. multifasciatus “Okavango” and N. multifasciatus “Zambezi” lineages. Pigmentation pattern variation occurred within this group, but none that could be assigned to a particular lineage. The N. machadoi species group in southern Africa consists of five lineages: N. machadoi “Zambezi 1”, N. machadoi “Zambezi 2”, N. machadoi “Kafue 1”, N. machadoi “Kafue 2”, and N. machadoi “Okavango”. This group displayed shallower genetic divergence between lineages than the other southern African Nannocharax species groups (0.4-1.3%). This shallow genetic divergence is paralleled by near complete morphological overlap, with PCA and DFA producing overlapping clusters, and measurements, meristics, and pigmentation pattern metrics consisting of very similar values for the lineages. These results indicate that what is considered to be “N. macropterus” in southern Africa should not be named as such. The N. macropterus “Zambezi” and the N. macropterus “Okavango 1” lineages, are misidentifications of Nannocharax dageti. Other “N. macropterus” from the southern African region possesses fewer circumpeduncular scales than the true N. macropterus as described by Pellegrin (1926), and require taxonomic re-evaluation, each here being recognised as a unique lineage with species status, here named N. macropterus “Okavango 2” and N. macropterus “Kwanza”. In particular, N. macropterus “Kwanza” displays deep genetic divergence as well as morphological dissimilarity with the other southern African “N. macropterus” groups. Nannocharax fasciolaris and N. monardi are here placed as junior synonyms of N. multifasciatus, owing to vast overlaps in measurements and character counts of these species and N. multifasciatus, which is also known to occur within the same geographical distribution, as well as dubious arguments from the original publications in delineating these species from N. multifasciatus. Therefore, there is insufficient evidence indicating the presence of multiple species originating from the Okavango system, where it is here indicated that only a single lineage of banded, adipose fin-bearing Nannocharax occurs, namely N. multifasciatus “Okavango”.
- Full Text:
- Date Issued: 2019
The origin of bedrock depression wetlands in the southern Cape of South Africa: a changing perspective
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
The predictors of student performance in a blended learning environment at Higher Education Institutions (HEIs) in Tanzania: a case study conducted at the University of Dar-es-Salaam
- Authors: Kabudi, Tumaini John
- Date: 2019
- Subjects: Prediction of scholastic success -- Tanzania -- Case studies , Motivation in education -- Tanzania -- Case studies , Academic achievement -- Tanzania -- Case studies , Blended learning -- Tanzania -- Case studies , Chuo Kikuu cha Dar es Salaam -- Students
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68358 , vital:29242
- Description: Blended Learning is an important technological platform which has the potential to enhance the efficiency and efficacy of educational provision, especially in Tanzania universities. Despite a high level of investment into Blended learning, students face various challenges that have impeded them performing well in Blended learning courses. The purpose of this research is to examine and explore how student’s performance in a Blended learning environment is influenced by motivation and learning strategies; using the University of Dar es Salaam as a case study. This is a pragmatic research that utilises a mixed research design. The research design includes both qualitative design (in-depth single case study) and quantitative design (survey). The target population for this study is students participating in Blended learning modules. Primary data will be collected by means of Motivational Strategies for Learning Questionnaire and observation. It was found that motivation and learning strategies are significant predictors of student performance in a Blended learning environment. In terms of the motivation categories, Intrinsic Goal Orientation and Self-efficacy have statistically significant effect on student performance. With learning strategies sub factors, it was found out that Rehearsal, Effort Regulation and Peer Learning have significance effect on student performance. Moreover, age and gender significantly influence performance. The findings obtained are significant in building a better understanding of the influence that the mentioned predictors have on predicting the performance of students in Blended learning courses in Tanzania.
- Full Text:
- Date Issued: 2019
- Authors: Kabudi, Tumaini John
- Date: 2019
- Subjects: Prediction of scholastic success -- Tanzania -- Case studies , Motivation in education -- Tanzania -- Case studies , Academic achievement -- Tanzania -- Case studies , Blended learning -- Tanzania -- Case studies , Chuo Kikuu cha Dar es Salaam -- Students
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68358 , vital:29242
- Description: Blended Learning is an important technological platform which has the potential to enhance the efficiency and efficacy of educational provision, especially in Tanzania universities. Despite a high level of investment into Blended learning, students face various challenges that have impeded them performing well in Blended learning courses. The purpose of this research is to examine and explore how student’s performance in a Blended learning environment is influenced by motivation and learning strategies; using the University of Dar es Salaam as a case study. This is a pragmatic research that utilises a mixed research design. The research design includes both qualitative design (in-depth single case study) and quantitative design (survey). The target population for this study is students participating in Blended learning modules. Primary data will be collected by means of Motivational Strategies for Learning Questionnaire and observation. It was found that motivation and learning strategies are significant predictors of student performance in a Blended learning environment. In terms of the motivation categories, Intrinsic Goal Orientation and Self-efficacy have statistically significant effect on student performance. With learning strategies sub factors, it was found out that Rehearsal, Effort Regulation and Peer Learning have significance effect on student performance. Moreover, age and gender significantly influence performance. The findings obtained are significant in building a better understanding of the influence that the mentioned predictors have on predicting the performance of students in Blended learning courses in Tanzania.
- Full Text:
- Date Issued: 2019
The preparation of BODIPY and porphyrin dyes and their cyclodextrin inclusion complexes and Pluronic® F-127 encapsulation micelles for use in PDT and PACT
- Authors: Molupe, Nthabeleng
- Date: 2019
- Subjects: Dyes and dyeing -- Chemistry , Drug delivery systems , Fluorescence spectroscopy , Cancer -- Photochemotherapy , Photosensitizing compounds -- Therapeutic use , Cyclodextrins -- Biotechnology , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117574 , vital:34528
- Description: Several novel BODIPY dyes ((4,4′-difluoro-1,7-tetramethyl-3,5-(3-dithiophene)-2,6-diiodo-8-(4-dimethylamino)-4-bora-3a,4a-diaza-s-indacene (1c), 4,4′-difluoro-1,7-tetramethyl-3,5-(3 dithiophene)-2,6-diiodo-8-(4-methylthio)-4-bora-3a,4a-diaza-s-indacene (3c) and 4,4′-difluoro-1,7-tetramethyl-3,5-(4-dibenzyloxybenzene)-2,6-diiodo-8-(4-methylbenzoate)-4 bora-3a,4a-diaza-s-indacene (4c)) and porphyrins (tetraacenaphthylporphyrin (7a) and Sn(IV) tetraacenaphthylporphyrin (7b)) were synthesized and characterized. Previously reported BODIPY dyes (4,4′-difluoro-1,7-tetramethyl-3,5-(2-dihydroxy)-2,6-diiodo-8-(4-bromo)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4′-difluoro-1,7-tetramethyl-3,5-(2-dithiophene)-2,6-diiodo-8-(phenyl)-4-bora-3a,4a-diaza-s-indacene (6)) were also used. Pluronic® F-127 and cyclodextrins were used as solubilizing drug delivery agents for the synthesized BODIPY dyes. The encapsulation of BODIPY dyes with Pluronic® F-127 micelles improved the water solubility of the BODIPY 5. Further modification of Pluronic® F-127 by coating with folate-functionalized chitosan for targeted delivery of BODIPY 1c and 6 was explored. The BODIPY dyes and their encapsulation complexes exhibited significant inhibition of human MCF-7 breast cancer cell growth. When cyclodextrins were used as nanocarriers, the inclusion complexes of BODIPY 4c with mβCD were found to enhance the water-solubility of the dye. Greater photoinactivation of Staphylococcus aureus was observed for the inclusion complexes when compared to the effect of solutions of non-complexed BODIPY 4c. The cyclodextrin inclusion complexes of porphyrin 7b with mβCD were also found to enhance the water-solubility of 7b. When the photodynamic effect was evaluated, solutions of the porphyrin alone and their inclusion complexes were found to have significant photodynamic effects against human MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2019
- Authors: Molupe, Nthabeleng
- Date: 2019
- Subjects: Dyes and dyeing -- Chemistry , Drug delivery systems , Fluorescence spectroscopy , Cancer -- Photochemotherapy , Photosensitizing compounds -- Therapeutic use , Cyclodextrins -- Biotechnology , Nanoparticles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117574 , vital:34528
- Description: Several novel BODIPY dyes ((4,4′-difluoro-1,7-tetramethyl-3,5-(3-dithiophene)-2,6-diiodo-8-(4-dimethylamino)-4-bora-3a,4a-diaza-s-indacene (1c), 4,4′-difluoro-1,7-tetramethyl-3,5-(3 dithiophene)-2,6-diiodo-8-(4-methylthio)-4-bora-3a,4a-diaza-s-indacene (3c) and 4,4′-difluoro-1,7-tetramethyl-3,5-(4-dibenzyloxybenzene)-2,6-diiodo-8-(4-methylbenzoate)-4 bora-3a,4a-diaza-s-indacene (4c)) and porphyrins (tetraacenaphthylporphyrin (7a) and Sn(IV) tetraacenaphthylporphyrin (7b)) were synthesized and characterized. Previously reported BODIPY dyes (4,4′-difluoro-1,7-tetramethyl-3,5-(2-dihydroxy)-2,6-diiodo-8-(4-bromo)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4′-difluoro-1,7-tetramethyl-3,5-(2-dithiophene)-2,6-diiodo-8-(phenyl)-4-bora-3a,4a-diaza-s-indacene (6)) were also used. Pluronic® F-127 and cyclodextrins were used as solubilizing drug delivery agents for the synthesized BODIPY dyes. The encapsulation of BODIPY dyes with Pluronic® F-127 micelles improved the water solubility of the BODIPY 5. Further modification of Pluronic® F-127 by coating with folate-functionalized chitosan for targeted delivery of BODIPY 1c and 6 was explored. The BODIPY dyes and their encapsulation complexes exhibited significant inhibition of human MCF-7 breast cancer cell growth. When cyclodextrins were used as nanocarriers, the inclusion complexes of BODIPY 4c with mβCD were found to enhance the water-solubility of the dye. Greater photoinactivation of Staphylococcus aureus was observed for the inclusion complexes when compared to the effect of solutions of non-complexed BODIPY 4c. The cyclodextrin inclusion complexes of porphyrin 7b with mβCD were also found to enhance the water-solubility of 7b. When the photodynamic effect was evaluated, solutions of the porphyrin alone and their inclusion complexes were found to have significant photodynamic effects against human MCF-7 breast cancer cells.
- Full Text:
- Date Issued: 2019
The relative roles of ecosystem services and disservices in rural livelihoods in the Eastern Cape, South Africa
- Authors: Herd-Hoare, Shannon
- Date: 2019
- Subjects: Ecosystem services -- Health aspects -- South Africa , South Africa -- Rural conditions , Biodiversity -- South Africa -- Health aspects , Rural development -- South Africa -- Health aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94080 , vital:30998
- Description: Since the publication of the Millennium Ecosystem Assessment report there has been a marked increase in research into various aspects of ecosystem services (ES). While ES are essential to human wellbeing, the literature has overlooked that some ecosystem goods and services also undermine human wellbeing. These are known as Ecosystem Disservices (EDS). This study aims to counter this imbalance in research, specifically in the context of rural livelihoods which are frequently dependent on local ES but often ill-equipped to manage EDS. The objectives of this study, conducted in three rural villages along a gradient of habitat diversity, were to identify a range of ES and EDS, determine their perceived contributions to or effects on the wellbeing of respondents, and identify modifications in livelihood strategies in response to EDS. The research made use of household surveys in conjunction with participatory learning and action techniques, such as focus group discussions in which ranking and trendline exercises, timelines, and participatory mapping were conducted. Findings indicated that although numerous participants were involved in the harvest of multiple ES, such as Non-Timber Forest Products (NTFPs), livestock outputs, crops and marine wildlife, they simultaneously experienced losses from EDS, such as ticks, unpalatable grass species, monkeys, and Lantana camara invasion which undermined livelihoods to varying degrees. The role of ES and EDS in livelihoods was expressed in economic terms, representing a common framework with which to illustrate the magnitude of their contribution or loss. For example, the average value of livestock goods and services, amongst those who owned and used outputs, was highest in the least biodiverse village at R9 753 per annum, while the corresponding value of potential livestock goods and services lost due to EDS, despite active implementation of prevention measures, totalled R22 426. Further, the average value of cultivated plots in the most biodiverse village could have totalled approximately R20 958, but because of EDS, represented less than 20% of this value. Further, the findings highlighted that the most biodiverse village also had the highest number of EDS, supporting Dunn (2010) who hypothesised that the number of EDS increases with the number of ES. Based on these findings, I propose that a comprehensive framework which systematically contextualises both the positive and negative contributions of ES is needed to grasp the full picture of how local people conceive and engage with nature to facilitate an understanding of the resulting practices and processes.
- Full Text:
- Date Issued: 2019
- Authors: Herd-Hoare, Shannon
- Date: 2019
- Subjects: Ecosystem services -- Health aspects -- South Africa , South Africa -- Rural conditions , Biodiversity -- South Africa -- Health aspects , Rural development -- South Africa -- Health aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94080 , vital:30998
- Description: Since the publication of the Millennium Ecosystem Assessment report there has been a marked increase in research into various aspects of ecosystem services (ES). While ES are essential to human wellbeing, the literature has overlooked that some ecosystem goods and services also undermine human wellbeing. These are known as Ecosystem Disservices (EDS). This study aims to counter this imbalance in research, specifically in the context of rural livelihoods which are frequently dependent on local ES but often ill-equipped to manage EDS. The objectives of this study, conducted in three rural villages along a gradient of habitat diversity, were to identify a range of ES and EDS, determine their perceived contributions to or effects on the wellbeing of respondents, and identify modifications in livelihood strategies in response to EDS. The research made use of household surveys in conjunction with participatory learning and action techniques, such as focus group discussions in which ranking and trendline exercises, timelines, and participatory mapping were conducted. Findings indicated that although numerous participants were involved in the harvest of multiple ES, such as Non-Timber Forest Products (NTFPs), livestock outputs, crops and marine wildlife, they simultaneously experienced losses from EDS, such as ticks, unpalatable grass species, monkeys, and Lantana camara invasion which undermined livelihoods to varying degrees. The role of ES and EDS in livelihoods was expressed in economic terms, representing a common framework with which to illustrate the magnitude of their contribution or loss. For example, the average value of livestock goods and services, amongst those who owned and used outputs, was highest in the least biodiverse village at R9 753 per annum, while the corresponding value of potential livestock goods and services lost due to EDS, despite active implementation of prevention measures, totalled R22 426. Further, the average value of cultivated plots in the most biodiverse village could have totalled approximately R20 958, but because of EDS, represented less than 20% of this value. Further, the findings highlighted that the most biodiverse village also had the highest number of EDS, supporting Dunn (2010) who hypothesised that the number of EDS increases with the number of ES. Based on these findings, I propose that a comprehensive framework which systematically contextualises both the positive and negative contributions of ES is needed to grasp the full picture of how local people conceive and engage with nature to facilitate an understanding of the resulting practices and processes.
- Full Text:
- Date Issued: 2019
The remote sensing of fires and their effects on soil properties in the uKhahlamba Drakensberg Park
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
The suspended sediment yield and provenance of the Inxu River Catchment, Eastern Cape
- Authors: Nyamela, Namso
- Date: 2019
- Subjects: Suspended sediments -- South Africa -- Inxu River , Sedimentation and deposition -- South Africa -- Inxu River , Watershed management -- South Africa -- Inxu River , Erosion -- South Africa -- Inxu River , Soil erosion -- South Africa -- Inxu River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72150 , vital:30010
- Description: The excessive deposition and accumulation of suspended sediment leads to the degradation of water resources such as dams and rivers. For the purpose of preserving and protecting these resources, suspended sediment needs to be managed, and its management should be catchment-wide and catchment-specific. This is certainly the case for the eroded Inxu River Catchment, which has been identified as a major contributor of sediment to the planned Lalini Dam on the Tsitsa River (a tributary of the Mzimvubu River). Knowledge of suspended sediment flux and catchment sources will aid the design of relevant strategies to manage suspended sediment production. Suspended sediment flux was determined from sediment samples that were collected using citizen-based monitoring techniques at calendar- and event-based sampling frequency, along with discharges estimated using stage-discharge relationships. Sediment source areas were identified by determining the suspended sediment contribution from major sub-catchments and observing similarities in the characteristics of the sub-catchments that produced the most sediment. The Inxu River Catchment produced 5.5 t/ha/yr between 01 May 2016 and 30 April 2017. When compared to modelled sediment yield (7 t/ha/yr) from Le Roux et al. (2015), modelled output was not far off from the measured results and both measured and modelled results identified similar sediment source areas. Q-SSC relationships observed at the Inxu River Outlet indicated that sediment was eroded from local areas and sub-catchment sediment contribution confirmed that most of the sediment was from the lower Inxu River Catchment. Within this area, the Ncolosi and Qwakele River Sub-catchments were major sediment source areas and were subject to widespread gully erosion. Gully erosion was prominent on gentle slopes, foot slopes and valley-bottoms that have concave slope curvature and lie on the Tarkastad Formation. This Formation is associated with some of the most dispersive soils in the area. Moreover, the catchment is vulnerable to erosion due to cultivation and subsequent land abandonment, continuous grazing and dense rural populations. Other studies in the Mzimvubu catchment identified similar catchment characteristics that contribute to excessive erosion. This study has successfully measured sediment yield and identified areas that should be targeted and prioritised for rehabilitation within the Inxu River Catchment. The findings could be applied to a wider catchment scale. The study has successfully demonstrated the use of citizen-based monitoring and desktop techniques and has also identified some pitfalls of this approach.
- Full Text:
- Date Issued: 2019
- Authors: Nyamela, Namso
- Date: 2019
- Subjects: Suspended sediments -- South Africa -- Inxu River , Sedimentation and deposition -- South Africa -- Inxu River , Watershed management -- South Africa -- Inxu River , Erosion -- South Africa -- Inxu River , Soil erosion -- South Africa -- Inxu River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72150 , vital:30010
- Description: The excessive deposition and accumulation of suspended sediment leads to the degradation of water resources such as dams and rivers. For the purpose of preserving and protecting these resources, suspended sediment needs to be managed, and its management should be catchment-wide and catchment-specific. This is certainly the case for the eroded Inxu River Catchment, which has been identified as a major contributor of sediment to the planned Lalini Dam on the Tsitsa River (a tributary of the Mzimvubu River). Knowledge of suspended sediment flux and catchment sources will aid the design of relevant strategies to manage suspended sediment production. Suspended sediment flux was determined from sediment samples that were collected using citizen-based monitoring techniques at calendar- and event-based sampling frequency, along with discharges estimated using stage-discharge relationships. Sediment source areas were identified by determining the suspended sediment contribution from major sub-catchments and observing similarities in the characteristics of the sub-catchments that produced the most sediment. The Inxu River Catchment produced 5.5 t/ha/yr between 01 May 2016 and 30 April 2017. When compared to modelled sediment yield (7 t/ha/yr) from Le Roux et al. (2015), modelled output was not far off from the measured results and both measured and modelled results identified similar sediment source areas. Q-SSC relationships observed at the Inxu River Outlet indicated that sediment was eroded from local areas and sub-catchment sediment contribution confirmed that most of the sediment was from the lower Inxu River Catchment. Within this area, the Ncolosi and Qwakele River Sub-catchments were major sediment source areas and were subject to widespread gully erosion. Gully erosion was prominent on gentle slopes, foot slopes and valley-bottoms that have concave slope curvature and lie on the Tarkastad Formation. This Formation is associated with some of the most dispersive soils in the area. Moreover, the catchment is vulnerable to erosion due to cultivation and subsequent land abandonment, continuous grazing and dense rural populations. Other studies in the Mzimvubu catchment identified similar catchment characteristics that contribute to excessive erosion. This study has successfully measured sediment yield and identified areas that should be targeted and prioritised for rehabilitation within the Inxu River Catchment. The findings could be applied to a wider catchment scale. The study has successfully demonstrated the use of citizen-based monitoring and desktop techniques and has also identified some pitfalls of this approach.
- Full Text:
- Date Issued: 2019
The time course changes in selected fatigue indicators in moderately trained participants
- Authors: Maduna, Bongani Cyprian
- Date: 2019
- Subjects: Athletes -- Health and hygiene , Fatigue , Athletes -- Physiology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76354 , vital:30553
- Description: Background: During daily physical activities, individuals will encounter some level of fatigue. This is especially true for athletes who exert their bodies to achieve superior performance and attempt to delay the onset of fatigue as far as possible. However, fatigue is a progressive process that is part of physical exercise. It is therefore, important to understand the various factors associated with fatigue. Objective: The purpose of this research project was to observe the changes in perceptual, physiological responses, and workload while participants performed a fatiguing cycling exercise task. In order to observe the aforementioned changes, one of the three variables, either perceptual, physiological responses or workload was kept constant, while the other two were observed as dependent variables. There were three test conditions, which permitted each variable to be kept constant in at least one of the three test conditions. Methods: Thirty-six apparently healthy university students were recruited for the study. The exercise was of 35 minute duration for each condition, with the data collection for HR (physiological response), RPE (perceptual response), and power output (workload) occurring at two minute intervals from the eighth minute until the thirtieth minute. The participants were required to perform a peak-power-output test in order set the relative performance ranges for each participant in order to elicit an observable fatigue response from all the participants. The three conditions included constant HR response, constant workload, and constant RPE response where each participant performed all of the above conditions on separate days.Results: The perceptual (RPE) response increased significantly (p<0.05) over time in all three test conditions, even under the constant RPE condition where it was expected to remain unchanged throughout the test duration. The HR response only demonstrated a significant (p<0.05) increase over time under the constant workload condition. Lastly, workload remained constant in all three testing conditions. Conclusion: Participants may be able to exercise for longer periods during sub-maximal exercise if they disregard the RPE warning response. In the current study, the RPE response illustrated that participants were being exerted more over time; however, the participants still had physiological and workload capacity to continue exercising. This research project has confirmed the fact that fatigue is a multifaceted phenomenon. Furthermore, it has been illustrated that RPE response alone as an indicator of fatigue onset may be misleading as participants did not breach the HR and workload steady state during the current research. Therefore, it may be more appropriate to assess fatigue onset through the assessment of more than one fatigue variable in order to ensure increased accuracy of the participants’ fatigue state assessment.
- Full Text:
- Date Issued: 2019
- Authors: Maduna, Bongani Cyprian
- Date: 2019
- Subjects: Athletes -- Health and hygiene , Fatigue , Athletes -- Physiology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76354 , vital:30553
- Description: Background: During daily physical activities, individuals will encounter some level of fatigue. This is especially true for athletes who exert their bodies to achieve superior performance and attempt to delay the onset of fatigue as far as possible. However, fatigue is a progressive process that is part of physical exercise. It is therefore, important to understand the various factors associated with fatigue. Objective: The purpose of this research project was to observe the changes in perceptual, physiological responses, and workload while participants performed a fatiguing cycling exercise task. In order to observe the aforementioned changes, one of the three variables, either perceptual, physiological responses or workload was kept constant, while the other two were observed as dependent variables. There were three test conditions, which permitted each variable to be kept constant in at least one of the three test conditions. Methods: Thirty-six apparently healthy university students were recruited for the study. The exercise was of 35 minute duration for each condition, with the data collection for HR (physiological response), RPE (perceptual response), and power output (workload) occurring at two minute intervals from the eighth minute until the thirtieth minute. The participants were required to perform a peak-power-output test in order set the relative performance ranges for each participant in order to elicit an observable fatigue response from all the participants. The three conditions included constant HR response, constant workload, and constant RPE response where each participant performed all of the above conditions on separate days.Results: The perceptual (RPE) response increased significantly (p<0.05) over time in all three test conditions, even under the constant RPE condition where it was expected to remain unchanged throughout the test duration. The HR response only demonstrated a significant (p<0.05) increase over time under the constant workload condition. Lastly, workload remained constant in all three testing conditions. Conclusion: Participants may be able to exercise for longer periods during sub-maximal exercise if they disregard the RPE warning response. In the current study, the RPE response illustrated that participants were being exerted more over time; however, the participants still had physiological and workload capacity to continue exercising. This research project has confirmed the fact that fatigue is a multifaceted phenomenon. Furthermore, it has been illustrated that RPE response alone as an indicator of fatigue onset may be misleading as participants did not breach the HR and workload steady state during the current research. Therefore, it may be more appropriate to assess fatigue onset through the assessment of more than one fatigue variable in order to ensure increased accuracy of the participants’ fatigue state assessment.
- Full Text:
- Date Issued: 2019
The use of filter-feeding fish (Clarias gariepinus and Oreochromis mossambicus) to remove microalgae from brewery effluent treatment ponds
- Authors: Nombembe, Lwazi
- Date: 2019
- Subjects: Clarias gariepinus -- Food , Mozambique tilapia -- Food , Water -- Purification -- South Africa , Algae -- Biotechnology -- South Africa , Microalgae -- Biotechnology-- South Africa , Brewery waste -- South Africa , Fish culture -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95745 , vital:31194
- Description: The removal of microalgae from high rate algal ponds (HRAP) in waste-water treatment systems remains a constraint to their use in effluent treatment systems. Conventional algae harvesting methods often have high energy demands, take up lots of space, are expensive to operate or are time consuming. The aim of the study was to determine if fish such as Clarias gariepinus and Oreochromis mossambicus, could be used to remove microalgae from waste-water treatment ponds (in the absence/presence of a flocculent in the former and in the absence or presence of pH moderation in the latter), and to investigate the subsequent influence of algae concentration on several water quality parameters. The age of Clarias gariepinus (3-12 months) had a positive relationship with the distance between gill rakers (98.27 to 163.34 μm; y=90.576+4.823*x: R²=0.549; F(1,18)=21.867; p<0.001) and these data suggested that these fish might be efficient at removing algae from HRAP effluent. However, this was not the case, even with flocculent application (but this result might have been confounded by very high pH readings, at which flocculation is less likely to occur). Oreochromis mossambicus removed some of this algae, but the pH was too high for tilapia culture. It was not possible to moderate the increase in pH by keeping tanks in the dark and thus preventing photosynthesis; but pH fluctuation in HRAP effluent could be moderated using CO2 sparging in an attempt to make the environment more hospitable for tilapia (the average pH that was moderated with CO2 was 8.43±0.06, whereas the unmoderated average was 10.65±0.06). However, pH moderation using CO2 sparging did not increase the rate at which algae were removed by O. mossambicus; rather, it compromised O2 concentration which dropped to 4.17±1.26 mg/l after five hours of CO2 sparging, whereas it increased to 20.50±1.41 mg/l in treatments with unadjusted pH over the same period. Fish can be used to remove algae from treated effluent, and Oreochromis mossambicus remains a recommended species. Future work needs to investigate moderating fluctuations in pH and O2 concentration to further facilitate this method of algae removal.
- Full Text:
- Date Issued: 2019
- Authors: Nombembe, Lwazi
- Date: 2019
- Subjects: Clarias gariepinus -- Food , Mozambique tilapia -- Food , Water -- Purification -- South Africa , Algae -- Biotechnology -- South Africa , Microalgae -- Biotechnology-- South Africa , Brewery waste -- South Africa , Fish culture -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95745 , vital:31194
- Description: The removal of microalgae from high rate algal ponds (HRAP) in waste-water treatment systems remains a constraint to their use in effluent treatment systems. Conventional algae harvesting methods often have high energy demands, take up lots of space, are expensive to operate or are time consuming. The aim of the study was to determine if fish such as Clarias gariepinus and Oreochromis mossambicus, could be used to remove microalgae from waste-water treatment ponds (in the absence/presence of a flocculent in the former and in the absence or presence of pH moderation in the latter), and to investigate the subsequent influence of algae concentration on several water quality parameters. The age of Clarias gariepinus (3-12 months) had a positive relationship with the distance between gill rakers (98.27 to 163.34 μm; y=90.576+4.823*x: R²=0.549; F(1,18)=21.867; p<0.001) and these data suggested that these fish might be efficient at removing algae from HRAP effluent. However, this was not the case, even with flocculent application (but this result might have been confounded by very high pH readings, at which flocculation is less likely to occur). Oreochromis mossambicus removed some of this algae, but the pH was too high for tilapia culture. It was not possible to moderate the increase in pH by keeping tanks in the dark and thus preventing photosynthesis; but pH fluctuation in HRAP effluent could be moderated using CO2 sparging in an attempt to make the environment more hospitable for tilapia (the average pH that was moderated with CO2 was 8.43±0.06, whereas the unmoderated average was 10.65±0.06). However, pH moderation using CO2 sparging did not increase the rate at which algae were removed by O. mossambicus; rather, it compromised O2 concentration which dropped to 4.17±1.26 mg/l after five hours of CO2 sparging, whereas it increased to 20.50±1.41 mg/l in treatments with unadjusted pH over the same period. Fish can be used to remove algae from treated effluent, and Oreochromis mossambicus remains a recommended species. Future work needs to investigate moderating fluctuations in pH and O2 concentration to further facilitate this method of algae removal.
- Full Text:
- Date Issued: 2019
Time motion analyses of one-day international and twenty/20 matches and the development of a simulated batting protocol specifically designed for female cricket players
- Authors: Munro, Catherine
- Date: 2019
- Subjects: Women cricket players , Cricket -- Batting , Cricket -- Coaching , Cricket -- Physiological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76342 , vital:30550
- Description: Background: Accurate and reliable in-game data is fundamental when designing effective batting training. A simulated batting protocol that could aid research and training has not been specifically designed for female cricketers because of a distinct lack of empirical in-game data for the women’s version of the game. Objective: The purpose of this study was to quantify the motion demands and run-breakdown of a century and T20 half-century for women’s cricket matches to establish a simulated batting protocol specifically designed for female batters. Method: Time-motion analyses of four one-day international and six T20 innings were conducted on international cricket matches played around the world between 2012 and 2017. The innings was divided into the bowling and batting innings. The ODI innings that met the criterion of 100 runs scored and T20 innings with scores above 50 runs were used in the run breakdown, which included scores from the top 10 countries ranked by the ICC. The time-motion analyses and century breakdown were utilised in the establishment of a simulated batting protocol. The simulated batting protocol for female batters was created/developed by utilising the method designed by Houghton et al., (2011), who developed the BATEX© protocol. Results: The time-motion analyses indicated that the mean duration of an ODI innings was 169 minutes. An over lasted 2.45 minutes, with 24.86 seconds between each delivery and 55 seconds between each over. When the bowling side changed to a new bowler, it was 1.12 minutes between overs. The mean score for the first power play in an ODI was 41 runs with 1.38 wickets being taken. The mean score during the second power play was 28 runs with 0.714 wickets being taken. The T20 bowling innings lasted 75.50 minutes, with an over lasting 2.52 minutes with 25.58 seconds between deliveries. The mean score in the T20 batting innings was 122 runs. During the power play, which lasted 24.35 minutes, 37 runs were scored with 1.45 wickets being taken. The simulated batting innings was then designed as four stages lasting the duration of a typical women’s century. Each stage was based on theoretical phases of play that may occur during a batting innings. Conclusion: The study indicated that the women’s game has different movement requirements compared to the men’s game in both the ODI and T20 formats. Further, the demands differ depending on the country that is playing. A training and research protocol specifically designed for female batters is an important outcome.
- Full Text:
- Date Issued: 2019
- Authors: Munro, Catherine
- Date: 2019
- Subjects: Women cricket players , Cricket -- Batting , Cricket -- Coaching , Cricket -- Physiological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76342 , vital:30550
- Description: Background: Accurate and reliable in-game data is fundamental when designing effective batting training. A simulated batting protocol that could aid research and training has not been specifically designed for female cricketers because of a distinct lack of empirical in-game data for the women’s version of the game. Objective: The purpose of this study was to quantify the motion demands and run-breakdown of a century and T20 half-century for women’s cricket matches to establish a simulated batting protocol specifically designed for female batters. Method: Time-motion analyses of four one-day international and six T20 innings were conducted on international cricket matches played around the world between 2012 and 2017. The innings was divided into the bowling and batting innings. The ODI innings that met the criterion of 100 runs scored and T20 innings with scores above 50 runs were used in the run breakdown, which included scores from the top 10 countries ranked by the ICC. The time-motion analyses and century breakdown were utilised in the establishment of a simulated batting protocol. The simulated batting protocol for female batters was created/developed by utilising the method designed by Houghton et al., (2011), who developed the BATEX© protocol. Results: The time-motion analyses indicated that the mean duration of an ODI innings was 169 minutes. An over lasted 2.45 minutes, with 24.86 seconds between each delivery and 55 seconds between each over. When the bowling side changed to a new bowler, it was 1.12 minutes between overs. The mean score for the first power play in an ODI was 41 runs with 1.38 wickets being taken. The mean score during the second power play was 28 runs with 0.714 wickets being taken. The T20 bowling innings lasted 75.50 minutes, with an over lasting 2.52 minutes with 25.58 seconds between deliveries. The mean score in the T20 batting innings was 122 runs. During the power play, which lasted 24.35 minutes, 37 runs were scored with 1.45 wickets being taken. The simulated batting innings was then designed as four stages lasting the duration of a typical women’s century. Each stage was based on theoretical phases of play that may occur during a batting innings. Conclusion: The study indicated that the women’s game has different movement requirements compared to the men’s game in both the ODI and T20 formats. Further, the demands differ depending on the country that is playing. A training and research protocol specifically designed for female batters is an important outcome.
- Full Text:
- Date Issued: 2019
TiRiFiG, a graphical 3D kinematic modelling tool
- Authors: Twum, Samuel Nyarko
- Date: 2019
- Subjects: Tilted Ring Fitting GUI , Astronomy -- Observations , Galaxies -- Observations , Galaxies -- Measurement , Galaxies -- Measurement -- Data processing , Kinematics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76409 , vital:30558
- Description: Galaxy kinematics is of crucial importance to understanding the structure, formation and evolution of galaxies. The studies of mass distributions giving rise to the missing mass problem, first raised by Zwicky (1933), give us an insight into dark matter distributions which are tightly linked to cosmology. Neutral hydrogen (H i) has been widely used as a tracer in the kinematic studies of galaxies. The Square Kilometre Array (SKA) and its precursors will produce large Hi datasets which will require kinematic modelling tools to extract kinematic parameters such as rotation curves. TiRiFiC (Józsa et al., 2007) is an example of such a tool for 3D kinematic modelling of resolved spectroscopic observations of rotating disks in terms of the tilted-ring model with varying complexities. TiRiFiC can be used to model a large number (20+) of parameters which are set in a configuration file (.def) for its execution. However, manually editing these parameters in a text editor is uncomfortable. In this work, we present TiRiFiG, Tilted Ring Fitting GUI, which is the graphical user interface that provides an easy way for parameter inputs to be modified in an interactive manner.
- Full Text:
- Date Issued: 2019
- Authors: Twum, Samuel Nyarko
- Date: 2019
- Subjects: Tilted Ring Fitting GUI , Astronomy -- Observations , Galaxies -- Observations , Galaxies -- Measurement , Galaxies -- Measurement -- Data processing , Kinematics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76409 , vital:30558
- Description: Galaxy kinematics is of crucial importance to understanding the structure, formation and evolution of galaxies. The studies of mass distributions giving rise to the missing mass problem, first raised by Zwicky (1933), give us an insight into dark matter distributions which are tightly linked to cosmology. Neutral hydrogen (H i) has been widely used as a tracer in the kinematic studies of galaxies. The Square Kilometre Array (SKA) and its precursors will produce large Hi datasets which will require kinematic modelling tools to extract kinematic parameters such as rotation curves. TiRiFiC (Józsa et al., 2007) is an example of such a tool for 3D kinematic modelling of resolved spectroscopic observations of rotating disks in terms of the tilted-ring model with varying complexities. TiRiFiC can be used to model a large number (20+) of parameters which are set in a configuration file (.def) for its execution. However, manually editing these parameters in a text editor is uncomfortable. In this work, we present TiRiFiG, Tilted Ring Fitting GUI, which is the graphical user interface that provides an easy way for parameter inputs to be modified in an interactive manner.
- Full Text:
- Date Issued: 2019
Towards defining the tipping point of tolerance to CO2-induced ocean acidification for the growth, development and metabolism of larval dusky kob Argyrosomus japonicus (Pisces: Sciaenidae)
- Authors: Mpopetsi, Pule Peter
- Date: 2019
- Subjects: Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Larvae , Argyrosomus -- Larvae -- Effect of water acidification on , Argyrosomus japonicus -- Larvae -- Nutrition , Argyrosomus -- Larvae -- Nutrition , Ocean acidification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71602 , vital:29924
- Description: Increased CO2 production and the consequent ocean acidification (OA) have been identified as one of the greatest threats to both calcifying and non-calcifying marine organisms. Traditionally, marine fishes, as non-calcifying organisms, were considered to have a higher tolerance to near-future OA conditions owing to their well-developed ion regulatory mechanisms. However, recent studies provide evidence to suggest that they may not be as resilient to near-future OA conditions as previously thought. In addition, earlier life stages of marine fishes are thought to be less tolerant than juveniles and adults of the same species as they lack well-developed ion regulatory mechanisms for maintaining homeostasis. This study follows up on previous studies examining the effects of near-future OA on larval Argyrosomus japonicus, an estuarine-dependent marine fish species, in order to identify the tipping point of tolerance for the larvae of this species. These previous studies showed that elevated pCO2, predicted for the year 2100, had negative effects on growth, development and metabolism and ultimately, survival of larval A. japonicus from post-flexion stage. Larval A. japonicus in the present study were reared from egg up to 22 DAH (days after hatching) under three treatments. The three treatments, (pCO2 353 μatm; pH 8.03), (pCO2 451 μatm; pH 7.93) and (pCO2 602 μatm; pH 7.83) corresponded to levels predicted to occur in year 2050, 2068 and 2090 respectively under the Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (IPCC RCP) 8.5 model. Size-at-hatch, growth, development and metabolic responses (standard and active metabolic rates and metabolic scope) were assessed and compared between the three treatments throughout the rearing period. Five earlier larval life stages (hatchling – flexion/post-flexion) were identified by the end of the experiment. There were no significant differences in size-at-hatch (P > 0.05), development or the active metabolic (P > 0.05) or metabolic scope (P > 0.05) of fish in the three treatments throughout the study. However, the standard metabolic rate was significantly higher in the year 2068 treatment but only at the flexion/post-flexion stage which could be attributed to differences in developmental rates (including the development of the gills) between the 2068 and the other two treatments. Overall, the metabolic scope was narrowest in the 2090 treatment, but varied according to life stage. Although not significantly different, metabolic scope in the 2090 treatment was noticeably lower at the flexion stage compared to the other two treatments, and the development appeared slower, suggesting that this could be the stage most prone to OA. The study concluded that, in isolation, OA levels predicted to occur between 2050 and 2090 will not negatively affect size-at-hatch, growth, development, and metabolic responses of larval A. japonicus up to 22 DAH (flexion/post-flexion stage). Taken together with the previous studies of the same species, the tipping point of tolerance (where negative impacts will begin) in larvae of the species appears to be between the years 2090 and 2100.
- Full Text:
- Date Issued: 2019
- Authors: Mpopetsi, Pule Peter
- Date: 2019
- Subjects: Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Larvae , Argyrosomus -- Larvae -- Effect of water acidification on , Argyrosomus japonicus -- Larvae -- Nutrition , Argyrosomus -- Larvae -- Nutrition , Ocean acidification
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/71602 , vital:29924
- Description: Increased CO2 production and the consequent ocean acidification (OA) have been identified as one of the greatest threats to both calcifying and non-calcifying marine organisms. Traditionally, marine fishes, as non-calcifying organisms, were considered to have a higher tolerance to near-future OA conditions owing to their well-developed ion regulatory mechanisms. However, recent studies provide evidence to suggest that they may not be as resilient to near-future OA conditions as previously thought. In addition, earlier life stages of marine fishes are thought to be less tolerant than juveniles and adults of the same species as they lack well-developed ion regulatory mechanisms for maintaining homeostasis. This study follows up on previous studies examining the effects of near-future OA on larval Argyrosomus japonicus, an estuarine-dependent marine fish species, in order to identify the tipping point of tolerance for the larvae of this species. These previous studies showed that elevated pCO2, predicted for the year 2100, had negative effects on growth, development and metabolism and ultimately, survival of larval A. japonicus from post-flexion stage. Larval A. japonicus in the present study were reared from egg up to 22 DAH (days after hatching) under three treatments. The three treatments, (pCO2 353 μatm; pH 8.03), (pCO2 451 μatm; pH 7.93) and (pCO2 602 μatm; pH 7.83) corresponded to levels predicted to occur in year 2050, 2068 and 2090 respectively under the Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (IPCC RCP) 8.5 model. Size-at-hatch, growth, development and metabolic responses (standard and active metabolic rates and metabolic scope) were assessed and compared between the three treatments throughout the rearing period. Five earlier larval life stages (hatchling – flexion/post-flexion) were identified by the end of the experiment. There were no significant differences in size-at-hatch (P > 0.05), development or the active metabolic (P > 0.05) or metabolic scope (P > 0.05) of fish in the three treatments throughout the study. However, the standard metabolic rate was significantly higher in the year 2068 treatment but only at the flexion/post-flexion stage which could be attributed to differences in developmental rates (including the development of the gills) between the 2068 and the other two treatments. Overall, the metabolic scope was narrowest in the 2090 treatment, but varied according to life stage. Although not significantly different, metabolic scope in the 2090 treatment was noticeably lower at the flexion stage compared to the other two treatments, and the development appeared slower, suggesting that this could be the stage most prone to OA. The study concluded that, in isolation, OA levels predicted to occur between 2050 and 2090 will not negatively affect size-at-hatch, growth, development, and metabolic responses of larval A. japonicus up to 22 DAH (flexion/post-flexion stage). Taken together with the previous studies of the same species, the tipping point of tolerance (where negative impacts will begin) in larvae of the species appears to be between the years 2090 and 2100.
- Full Text:
- Date Issued: 2019
Towards understanding and mitigating attacks leveraging zero-day exploits
- Authors: Smit, Liam
- Date: 2019
- Subjects: Computer crimes -- Prevention , Data protection , Hacking , Computer security , Computer networks -- Security measures , Computers -- Access control , Malware (Computer software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115718 , vital:34218
- Description: Zero-day vulnerabilities are unknown and therefore not addressed with the result that they can be exploited by attackers to gain unauthorised system access. In order to understand and mitigate against attacks leveraging zero-days or unknown techniques, it is necessary to study the vulnerabilities, exploits and attacks that make use of them. In recent years there have been a number of leaks publishing such attacks using various methods to exploit vulnerabilities. This research seeks to understand what types of vulnerabilities exist, why and how these are exploited, and how to defend against such attacks by either mitigating the vulnerabilities or the method / process of exploiting them. By moving beyond merely remedying the vulnerabilities to defences that are able to prevent or detect the actions taken by attackers, the security of the information system will be better positioned to deal with future unknown threats. An interesting finding is how attackers exploit moving beyond the observable bounds to circumvent security defences, for example, compromising syslog servers, or going down to lower system rings to gain access. However, defenders can counter this by employing defences that are external to the system preventing attackers from disabling them or removing collected evidence after gaining system access. Attackers are able to defeat air-gaps via the leakage of electromagnetic radiation as well as misdirect attribution by planting false artefacts for forensic analysis and attacking from third party information systems. They analyse the methods of other attackers to learn new techniques. An example of this is the Umbrage project whereby malware is analysed to decide whether it should be implemented as a proof of concept. Another important finding is that attackers respect defence mechanisms such as: remote syslog (e.g. firewall), core dump files, database auditing, and Tripwire (e.g. SlyHeretic). These defences all have the potential to result in the attacker being discovered. Attackers must either negate the defence mechanism or find unprotected targets. Defenders can use technologies such as encryption to defend against interception and man-in-the-middle attacks. They can also employ honeytokens and honeypots to alarm misdirect, slow down and learn from attackers. By employing various tactics defenders are able to increase their chance of detecting and time to react to attacks, even those exploiting hitherto unknown vulnerabilities. To summarize the information presented in this thesis and to show the practical importance thereof, an examination is presented of the NSA's network intrusion of the SWIFT organisation. It shows that the firewalls were exploited with remote code execution zerodays. This attack has a striking parallel in the approach used in the recent VPNFilter malware. If nothing else, the leaks provide information to other actors on how to attack and what to avoid. However, by studying state actors, we can gain insight into what other actors with fewer resources can do in the future.
- Full Text:
- Date Issued: 2019
- Authors: Smit, Liam
- Date: 2019
- Subjects: Computer crimes -- Prevention , Data protection , Hacking , Computer security , Computer networks -- Security measures , Computers -- Access control , Malware (Computer software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115718 , vital:34218
- Description: Zero-day vulnerabilities are unknown and therefore not addressed with the result that they can be exploited by attackers to gain unauthorised system access. In order to understand and mitigate against attacks leveraging zero-days or unknown techniques, it is necessary to study the vulnerabilities, exploits and attacks that make use of them. In recent years there have been a number of leaks publishing such attacks using various methods to exploit vulnerabilities. This research seeks to understand what types of vulnerabilities exist, why and how these are exploited, and how to defend against such attacks by either mitigating the vulnerabilities or the method / process of exploiting them. By moving beyond merely remedying the vulnerabilities to defences that are able to prevent or detect the actions taken by attackers, the security of the information system will be better positioned to deal with future unknown threats. An interesting finding is how attackers exploit moving beyond the observable bounds to circumvent security defences, for example, compromising syslog servers, or going down to lower system rings to gain access. However, defenders can counter this by employing defences that are external to the system preventing attackers from disabling them or removing collected evidence after gaining system access. Attackers are able to defeat air-gaps via the leakage of electromagnetic radiation as well as misdirect attribution by planting false artefacts for forensic analysis and attacking from third party information systems. They analyse the methods of other attackers to learn new techniques. An example of this is the Umbrage project whereby malware is analysed to decide whether it should be implemented as a proof of concept. Another important finding is that attackers respect defence mechanisms such as: remote syslog (e.g. firewall), core dump files, database auditing, and Tripwire (e.g. SlyHeretic). These defences all have the potential to result in the attacker being discovered. Attackers must either negate the defence mechanism or find unprotected targets. Defenders can use technologies such as encryption to defend against interception and man-in-the-middle attacks. They can also employ honeytokens and honeypots to alarm misdirect, slow down and learn from attackers. By employing various tactics defenders are able to increase their chance of detecting and time to react to attacks, even those exploiting hitherto unknown vulnerabilities. To summarize the information presented in this thesis and to show the practical importance thereof, an examination is presented of the NSA's network intrusion of the SWIFT organisation. It shows that the firewalls were exploited with remote code execution zerodays. This attack has a striking parallel in the approach used in the recent VPNFilter malware. If nothing else, the leaks provide information to other actors on how to attack and what to avoid. However, by studying state actors, we can gain insight into what other actors with fewer resources can do in the future.
- Full Text:
- Date Issued: 2019
Truth and reconciliation and other stories: a critical multimodal investigation of representations of post-apartheid South Africa in children's picturebooks: volume 1
- Authors: Smith, Jade
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97614 , vital:31458
- Description: Expected release date-April 2021
- Full Text: false
- Date Issued: 2019
- Authors: Smith, Jade
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97614 , vital:31458
- Description: Expected release date-April 2021
- Full Text: false
- Date Issued: 2019
Using captive seabirds to assess knowledge gaps in stable isotope analysis of diets
- Authors: Micklem, Isabel Andrea
- Date: 2019
- Subjects: Stable isotopes -- Analysis African penguin -- South Africa Breeding
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65101 , vital:28686
- Description: Stable isotope (SI) ratios of carbon (δ13C) and nitrogen (δ15N) are now widely used as biomarkers in ecological studies to provide information about food web structuring. However, understanding trophic relationships using SI analysis requires not only knowledge of SI values of predator and prey, but also accurate discrimination factors (DFs), which can differ among species and by physiological state. This thesis examined three questions using captive birds from the South African Foundation for the Conservation of Coastal Birds (SANCCOB). First, the effects of ontogeny on δ13C and δ15N ratios of African penguins (Spheniscus demersus) were assessed. Blood samples were collected from penguins in four age classes (P3 chicks, blues, juveniles and adults) concurrently with their diet (sardine (Sardinops sagax) and formula). Second, to assess the influence of breeding physiology on SI ratios, the blood of ten breeding pairs of penguins was sampled over a five-month period from June to October 2016. Following laying, each pair was categorised into one of three (four for whole blood) egg production phases (initial yolk deposition, rapid yolk deposition and post-laying) and their influences on SI ratios were tested. Third, species differences in DFs were evaluated for African penguins, kelp and Hartlaub’s gulls (Larus dominicanus and L. hartlaubii), greater crested terns (Thalasseus bergii) and Cape cormorants (Phalacrocorax capensis). Flying birds were mostly fed sardine with a small but unknown amount of sardinella (Sardinella aurita), DFs were therefore estimated for a 50:50 sardine:sardinella diet, a 75:25 sardine:sardinella diet and a 100% sardine diet for each flying bird species. The DFs were assessed for the whole blood (WB), red blood cells (RBC), plasma (PL) and delipidated plasma of the penguins, and only WB for the flying birds as well as flesh, whole fish, delipidated flesh and delipidated whole fish for fish species, and for formula. Results indicated that age influenced both the δ13C and δ15N of WB, only the δ15N of RBC and the δ13C of delipidated PL. The assessment of breeding physiology yielded a significant interaction between the effects of egg production phase and sex on the δ13C of WB; females had significantly lower δ13C in the rapid yolk deposition phase than the other two phases and all males. The δ13C of PL was affected only by sex, with females having a significantly lower δ13C value than males. Neither physiological state nor sex influenced the other blood components. Differences were found among the three DFs in the non-penguin species, but not for all consumer – prey tissue combinations. There were also significant differences among species with a DF calculated from a diet with the most probable prey proportions eaten. Depending on the combination of consumer and prey tissue used to calculate the DF, a different conclusion regarding trophic information can be reached. A literature review updated with the present data showed that no general pattern or grouping of similar species with regards to DF values could be drawn, highlighting the importance of determining species- and tissue-specific DFs. Thus age, egg production, tissue and species all influenced the SI values of bird blood and therefore their DFs. Not all physiological conditions affect all blood components in the same way, making different components more or less sensitive to physiological influences. Though their influence is at a small enough scale that it is unlikely to hamper correct conclusion in ecological studies, it is crucial that these factors are considered when using SI analysis (SIA). When uncertainties exist for some coefficients in wild studies, SIA should therefore be combined to other dietary techniques to determine the food web structure as best as possible.
- Full Text:
- Date Issued: 2019
- Authors: Micklem, Isabel Andrea
- Date: 2019
- Subjects: Stable isotopes -- Analysis African penguin -- South Africa Breeding
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65101 , vital:28686
- Description: Stable isotope (SI) ratios of carbon (δ13C) and nitrogen (δ15N) are now widely used as biomarkers in ecological studies to provide information about food web structuring. However, understanding trophic relationships using SI analysis requires not only knowledge of SI values of predator and prey, but also accurate discrimination factors (DFs), which can differ among species and by physiological state. This thesis examined three questions using captive birds from the South African Foundation for the Conservation of Coastal Birds (SANCCOB). First, the effects of ontogeny on δ13C and δ15N ratios of African penguins (Spheniscus demersus) were assessed. Blood samples were collected from penguins in four age classes (P3 chicks, blues, juveniles and adults) concurrently with their diet (sardine (Sardinops sagax) and formula). Second, to assess the influence of breeding physiology on SI ratios, the blood of ten breeding pairs of penguins was sampled over a five-month period from June to October 2016. Following laying, each pair was categorised into one of three (four for whole blood) egg production phases (initial yolk deposition, rapid yolk deposition and post-laying) and their influences on SI ratios were tested. Third, species differences in DFs were evaluated for African penguins, kelp and Hartlaub’s gulls (Larus dominicanus and L. hartlaubii), greater crested terns (Thalasseus bergii) and Cape cormorants (Phalacrocorax capensis). Flying birds were mostly fed sardine with a small but unknown amount of sardinella (Sardinella aurita), DFs were therefore estimated for a 50:50 sardine:sardinella diet, a 75:25 sardine:sardinella diet and a 100% sardine diet for each flying bird species. The DFs were assessed for the whole blood (WB), red blood cells (RBC), plasma (PL) and delipidated plasma of the penguins, and only WB for the flying birds as well as flesh, whole fish, delipidated flesh and delipidated whole fish for fish species, and for formula. Results indicated that age influenced both the δ13C and δ15N of WB, only the δ15N of RBC and the δ13C of delipidated PL. The assessment of breeding physiology yielded a significant interaction between the effects of egg production phase and sex on the δ13C of WB; females had significantly lower δ13C in the rapid yolk deposition phase than the other two phases and all males. The δ13C of PL was affected only by sex, with females having a significantly lower δ13C value than males. Neither physiological state nor sex influenced the other blood components. Differences were found among the three DFs in the non-penguin species, but not for all consumer – prey tissue combinations. There were also significant differences among species with a DF calculated from a diet with the most probable prey proportions eaten. Depending on the combination of consumer and prey tissue used to calculate the DF, a different conclusion regarding trophic information can be reached. A literature review updated with the present data showed that no general pattern or grouping of similar species with regards to DF values could be drawn, highlighting the importance of determining species- and tissue-specific DFs. Thus age, egg production, tissue and species all influenced the SI values of bird blood and therefore their DFs. Not all physiological conditions affect all blood components in the same way, making different components more or less sensitive to physiological influences. Though their influence is at a small enough scale that it is unlikely to hamper correct conclusion in ecological studies, it is crucial that these factors are considered when using SI analysis (SIA). When uncertainties exist for some coefficients in wild studies, SIA should therefore be combined to other dietary techniques to determine the food web structure as best as possible.
- Full Text:
- Date Issued: 2019