Conserving land for people: transformative adaptive co-management of sustainable protected areas in the eastern Democratic Republic of Congo
- Authors: Kalyongo, Kujirakwinja Deo
- Date: 2020
- Subjects: Protected areas -- Congo (Democratic Republic) , Protected areas -- Government policy -- Congo (Democratic Republic) , Protected areas -- Management -- Congo (Democratic Republic) , Conservation of natural resources -- Congo (Democratic Republic)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165912 , vital:41296
- Description: Conservation practices and approaches in the Democratic Republic of Congo (DRC), as in other parts of the world, have evolved from traditional to fortress and collaborative contemporary approaches such as adaptive co-management. These approaches aim to include multiple decision-makers using diversified resources and, existing formal and informal governance structures. Collaborative approaches also consider conflict resolution and external factors that can influence conservation outputs and outcomes. In the DRC context, conflicts over resources are related not only to resource access and power but also to the ineffectiveness of collaborative approaches that exclude stakeholders such as local communities. These conflicts have negatively affected protected areas and weakened the management and governance of protected areas. Therefore, evolving approaches such as adaptive co-management that consider power relations, the multi-scaled involvement of actors and learning loops to adjust strategies are seen as better options to improve the governance of protected areas and minimise the degradation of key ecosystems. My research explored the gazettement processes of three protected areas in the eastern DRC (Itombwe, Kabobo and Okapi Reserves). I focused on the influence of social-political, historical and psychological factors on the management and governance of protected areas in the DRC. In addition, the research reveals the inclusive gazettement processes of protected areas is the foundation of successful co-management approaches. I found that values and good governance practices play a key role in influencing local perceptions and support to conservation interventions. Whilst some conservation practitioners believe that economic benefits to communities are the most predominant motivating factor, I found that good conservation management practices can motivate communities to support protected area management. Bad management practices were related not only to inadequate conservation approaches and practices but also to factors such as corruption, inadequate law enforcement and the inappropriate equipment of rangers. Therefore, I suggest that long term protected area management in DRC should consider how the value of resources for communities and protected areas have been changing throughout the history of conservation, and how to best share power and responsibilities with local resource users and stakeholders. This is only possible if conservation practices and approaches, governance process and institutions are transformed at multiple levels.
- Full Text:
- Date Issued: 2020
- Authors: Kalyongo, Kujirakwinja Deo
- Date: 2020
- Subjects: Protected areas -- Congo (Democratic Republic) , Protected areas -- Government policy -- Congo (Democratic Republic) , Protected areas -- Management -- Congo (Democratic Republic) , Conservation of natural resources -- Congo (Democratic Republic)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165912 , vital:41296
- Description: Conservation practices and approaches in the Democratic Republic of Congo (DRC), as in other parts of the world, have evolved from traditional to fortress and collaborative contemporary approaches such as adaptive co-management. These approaches aim to include multiple decision-makers using diversified resources and, existing formal and informal governance structures. Collaborative approaches also consider conflict resolution and external factors that can influence conservation outputs and outcomes. In the DRC context, conflicts over resources are related not only to resource access and power but also to the ineffectiveness of collaborative approaches that exclude stakeholders such as local communities. These conflicts have negatively affected protected areas and weakened the management and governance of protected areas. Therefore, evolving approaches such as adaptive co-management that consider power relations, the multi-scaled involvement of actors and learning loops to adjust strategies are seen as better options to improve the governance of protected areas and minimise the degradation of key ecosystems. My research explored the gazettement processes of three protected areas in the eastern DRC (Itombwe, Kabobo and Okapi Reserves). I focused on the influence of social-political, historical and psychological factors on the management and governance of protected areas in the DRC. In addition, the research reveals the inclusive gazettement processes of protected areas is the foundation of successful co-management approaches. I found that values and good governance practices play a key role in influencing local perceptions and support to conservation interventions. Whilst some conservation practitioners believe that economic benefits to communities are the most predominant motivating factor, I found that good conservation management practices can motivate communities to support protected area management. Bad management practices were related not only to inadequate conservation approaches and practices but also to factors such as corruption, inadequate law enforcement and the inappropriate equipment of rangers. Therefore, I suggest that long term protected area management in DRC should consider how the value of resources for communities and protected areas have been changing throughout the history of conservation, and how to best share power and responsibilities with local resource users and stakeholders. This is only possible if conservation practices and approaches, governance process and institutions are transformed at multiple levels.
- Full Text:
- Date Issued: 2020
Post-apartheid nostalgia and the future of the black visual archive
- Nsele, Zamansele Nsikakazi Busisiwe
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
Biogeographic patterns of endolithic cyanobacteria and their negative impacts on mussels along the South African coast
- Authors: Ndhlovu, Aldwin
- Date: 2020
- Subjects: Cyanobacteria -- South Africa , Cyanobacteria -- Geographical distribution , Prokaryotes -- South Africa , Mexilhao mussel -- South Africa , Mytilus galloprovincialis -- South Africa , Coastal biology -- South Africa , Coastal ecology -- South Africa , Mussels -- Geographical distribution , Mussels -- Predators of , Mussels -- Mortality -- South Africa , Mussels -- Ecology -- South Africa , Mussels -- Growth -- South Africa , Mussels -- Fertility -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144656 , vital:38367
- Description: Endolithic cyanobacterial species occur in a wide range of environments including cold and hot deserts as well as marine systems where they attack biological material such as corals and the shells of molluscs including limpets, mussels and abalone. Endoliths live as parasites in mussel shells, where they erode and extract calcium carbonate leading to shell weakening, creating fracture holes that lead to shell collapse and death, but they also have positive effects when they lead to discolouration of mussel shells hence giving them the ability to reduce stressful heat gain during periods of extreme heat stress. Mussels are ecological engineers on which the abundance and diversity of associated species assemblages depend. Understanding how endolithic cyanobacteria affect mussels will not only help in predicting future patterns of mussel abundances, but also future patterns of the infauna that depend on them. Firstly, I identified endolithic species infesting mussels and assessed the prevalence of endolithic parasitism in two intertidal mussel species in South Africa, the native Perna perna and the invasive Mytilus galloprovincialis. Large-scale surveys of endolithic infestation of mussels were conducted along 2500 km of the South African coast, covering three biogeographic regions: the subtropical east coast, dominated by P. perna, the warm temperate south coast where the indigenous species coexists with M. galloprovincialis, and the cool temperate west coast which is dominated by M. galloprovincialis. The prevalence of endolithic infestation was higher in the cool temperate bioregion than in the warm temperate and subtropical bioregions which did not differ and for P. perna endolithic species assemblages revealed clear groupings by bioregion. Results for endolithic induced mortality followed the same trend, with no significant difference between the two mussel species where they coexist and these results attribute biogeography of endoliths to environmental factors rather than host identity. Secondly, I assessed energy budgets of infested and clean mussels, to evaluate the energetic cost of infestation. This involved measuring energy acquisition, expenditure, calculating scope for growth and lethal temperatures (LT50s). The results revealed that endolithic cyanobacteria have a negative effect on scope for growth due to increased metabolic rates for infested mussels, with no effect of endoliths on the rates or efficiency of energy acquisition through filtration and no effect on lethal temperatures. The effects of infestation were then examined in more detail through a qualitative and quantitative analysis of mussel gonads and byssal attachment strength to the substratum. Endolithic infestation was found to affect reproduction by affecting the size (mass) of gonads, but not the density of eggs within them. Attachment strength was affected by endolithic infestation with very infested mussels requiring much less force to detach them from the substratum compared to mussels with low or no infestation. These results show that endolithic infestation affects mussel fitness by directly affecting attachment strength and by reducing their reproductive output. Thirdly, endolithic succession within mussel shells was examined by assessing endolithic species composition in different regions of the shell and as a function of time. The results on the spatial distribution of endolith species within a shell supported those for temporal succession in shells deployed in the field. Endolithic species that were early colonists of clean shells were similar to those that were found in the distal edge, the new and growing region of the shell and species that arrived late in succession were similar to endolithic species found near the umbo, the oldest region of the shell. Overall, the study shows that endolithic cyanobacteria show the effects of biogeography on species distribution and clear patterns of succession within mussel shells. Cyanobacteria affect mussels negatively; they lead to low scope for growth and hence low growth rates, low reproductive output and reduced attachment strength for infested mussels. This, in turn is expected to have indirect consequences for other species that rely on mussels as ecological engineers for their survival.
- Full Text:
- Date Issued: 2020
- Authors: Ndhlovu, Aldwin
- Date: 2020
- Subjects: Cyanobacteria -- South Africa , Cyanobacteria -- Geographical distribution , Prokaryotes -- South Africa , Mexilhao mussel -- South Africa , Mytilus galloprovincialis -- South Africa , Coastal biology -- South Africa , Coastal ecology -- South Africa , Mussels -- Geographical distribution , Mussels -- Predators of , Mussels -- Mortality -- South Africa , Mussels -- Ecology -- South Africa , Mussels -- Growth -- South Africa , Mussels -- Fertility -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144656 , vital:38367
- Description: Endolithic cyanobacterial species occur in a wide range of environments including cold and hot deserts as well as marine systems where they attack biological material such as corals and the shells of molluscs including limpets, mussels and abalone. Endoliths live as parasites in mussel shells, where they erode and extract calcium carbonate leading to shell weakening, creating fracture holes that lead to shell collapse and death, but they also have positive effects when they lead to discolouration of mussel shells hence giving them the ability to reduce stressful heat gain during periods of extreme heat stress. Mussels are ecological engineers on which the abundance and diversity of associated species assemblages depend. Understanding how endolithic cyanobacteria affect mussels will not only help in predicting future patterns of mussel abundances, but also future patterns of the infauna that depend on them. Firstly, I identified endolithic species infesting mussels and assessed the prevalence of endolithic parasitism in two intertidal mussel species in South Africa, the native Perna perna and the invasive Mytilus galloprovincialis. Large-scale surveys of endolithic infestation of mussels were conducted along 2500 km of the South African coast, covering three biogeographic regions: the subtropical east coast, dominated by P. perna, the warm temperate south coast where the indigenous species coexists with M. galloprovincialis, and the cool temperate west coast which is dominated by M. galloprovincialis. The prevalence of endolithic infestation was higher in the cool temperate bioregion than in the warm temperate and subtropical bioregions which did not differ and for P. perna endolithic species assemblages revealed clear groupings by bioregion. Results for endolithic induced mortality followed the same trend, with no significant difference between the two mussel species where they coexist and these results attribute biogeography of endoliths to environmental factors rather than host identity. Secondly, I assessed energy budgets of infested and clean mussels, to evaluate the energetic cost of infestation. This involved measuring energy acquisition, expenditure, calculating scope for growth and lethal temperatures (LT50s). The results revealed that endolithic cyanobacteria have a negative effect on scope for growth due to increased metabolic rates for infested mussels, with no effect of endoliths on the rates or efficiency of energy acquisition through filtration and no effect on lethal temperatures. The effects of infestation were then examined in more detail through a qualitative and quantitative analysis of mussel gonads and byssal attachment strength to the substratum. Endolithic infestation was found to affect reproduction by affecting the size (mass) of gonads, but not the density of eggs within them. Attachment strength was affected by endolithic infestation with very infested mussels requiring much less force to detach them from the substratum compared to mussels with low or no infestation. These results show that endolithic infestation affects mussel fitness by directly affecting attachment strength and by reducing their reproductive output. Thirdly, endolithic succession within mussel shells was examined by assessing endolithic species composition in different regions of the shell and as a function of time. The results on the spatial distribution of endolith species within a shell supported those for temporal succession in shells deployed in the field. Endolithic species that were early colonists of clean shells were similar to those that were found in the distal edge, the new and growing region of the shell and species that arrived late in succession were similar to endolithic species found near the umbo, the oldest region of the shell. Overall, the study shows that endolithic cyanobacteria show the effects of biogeography on species distribution and clear patterns of succession within mussel shells. Cyanobacteria affect mussels negatively; they lead to low scope for growth and hence low growth rates, low reproductive output and reduced attachment strength for infested mussels. This, in turn is expected to have indirect consequences for other species that rely on mussels as ecological engineers for their survival.
- Full Text:
- Date Issued: 2020
Urbanisation, foraging and household food security in urban South Africa
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
- Full Text:
- Date Issued: 2020
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
- Full Text:
- Date Issued: 2020
Mechanism of action of non-synonymous single nucleotide variations associated with α-carbonic anhydrases II, IV and VIII
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
- Date Issued: 2020
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
- Date Issued: 2020
Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
Conceptualisations and pedagogical practices of academic literacy in Namibian higher education
- Authors: Julius, Lukas Homateni
- Date: 2021-04
- Subjects: Information literacy -- Study and teaching (Higher) -- Namibia , Academic writing -- Study and teaching -- Namibia , Qualitative research -- Methodology , Academic language -- Namibia , Information literacy -- Social aspects
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177293 , vital:42807 , 10.21504/10962/177293
- Description: The purpose of this study was to investigate academic literacy development lecturers’ conceptualisations of academic literacy and resultant pedagogical practices in academic development courses at three different Higher Education Institutional types in Namibia. The research sites were a Traditional University, a University of Technology and a Comprehensive University. The focus was to understand the extent to which the academics’ conceptions of academic literacy and the resultant pedagogical practices in the academic development courses at these three Higher Education Institutions (HEIs) facilitate epistemological access into students’ chosen fields of study. Bernstein’s Pedagogical theory (1990), Genre theory (1996) and Halliday’s Systemic Functional Linguistics (1978) were used as the study’s theoretical lenses and analytical framework. An interpretative paradigm and a qualitative case study design were employed as the research approach. Semi-structured interviews, classroom observations and documentary evidence were used to generate data. Research findings revealed a common (mis)conception of the nature of academic literacy, the resultant inadequate learning support offered to students in the selected academic literacy development courses, and a clear divorcing of academic literacy interventions from the students’ ‘home’ or mainstream disciplines at the three HEIs. The participants understood academic literacy from an autonomous position as a set of generic skills which could be taught outside of mainstream classes. Moreover, findings revealed that this understanding impacted on the design and assessments of all the academic literacy courses across the three universities under study. The study calls for a context sensitive model through which academic literacy acquisition can be scaffolded to meet the discipline-specific epistemological needs of the students. , Elalakano lyehokololoningomwa lyomapekapeko ndika olyo okukonakona ehumithokomeho lyomikalo dhokulesha nokushanga meilongngo lyopombada (oAcademic Literaci) maaputudhilongi, okukonakona omafatululo giisimanintsa moAcademic Literaci osho wo okutala iizemo yomikalo dhayooloka dhokulonga noku ilonga iilongwa yayooloka miiputudhilo yelongo lyopombada moNamibia. Omapekapeko ngaka oga li ga ningilwa miiputudhilo yomaukwatya ta ga landula; Oshiputudhiilo shopamudhigululwakalo, Oshiputudhilo shopaunongononi, nOshiputudilo shomailongo gaandjakana. Oshintsa shopokati shomapekapeko ngaka osho okuuva ko ondodo yowino osho wo euveko lyoAcademic Literaci maaputudhilongi nonkene euveko nontseyo ndjika tayi longithwa oku eta oshizemo tashi humitha komeho euveko lyopombanda lyaalongwa yomailongo geewino dhayooloka miiputudhilo itatu yelongo lyopombanda; shino otashi kwathele aalongwa yamone ontseyo ndjoka tayi ya kwathele meilongo lyawo. Omapekapeko ngano oga longitha omadhiladhiloukithi (eetheori) ga Bernstein’s Pedagogical theori (1990), Genre theori (1996) na Halliday’s Systemic Functional Linguistics theori (1978), mokufatulula nokundjandjukununa iizemo yomapekapeko. Omodela yokukonakona iizemo yongushu tayi ziilile maakonakonwa, oya tala ekonakono ndika onga oshintsa shopokati, oyo ya longithwa, opo ku monike uuyelele wothaathaa. Omikalo dha longifwa mokukonakona noku gongela uuyelele momapekapeko ngano ongaashi, eenkundathana dhayaali, omatalelo geetundi oshoyo omakonakono giinyanyangidhwa tayi kwandjangele nepekapeko ndika. Iizedjemo yepekapeko ndika otayi ulike kutya opena engwangwano montseyo nenge mefatululo lyuukwatya woAcademic Literaci, shoka sha eta enkundipalo meyambidhidho hali pewa aalongwa miilongwa yeewino dhayooloka. Shika otashi ulike kutya kapena etsokumwe pokati keenkambadhala tadhi ningwa kaapudhilongi dhokulonga oAcademic Litraci miilongwa ya yooloka mbyoka tayi ilongelwa kaalongwa miiputudhilo itatu yopombada. iizemmo yepekapeko olyo tuu mdika oya ulike wo kutya aalongwa mboka yaza komailongo ga yooloka oha yi ilongo nuudhigu opo ya pondole ondondo yomadhiladhilo gopombanda meilongo lyuukumwe. Mokukonakona euveko lyoAcademic Literaci, epekapeko ndika olya ndhindhilike kutya aakuthimbinga oyena euveko lyankundipala lyoterma ‘Academic Literaci,’ ano ya nyengwa okukwatakanitha oohedi dhopetameko ndhoka dhina oku ilongwa meikalekelo - ano pondje yiilongwa ikwao. Oshikwao, iizemo oya ulike kutya euveko ndika otali nwetha mo etungepo lyoAcademic Literaci onga oshilongwa, osho wo omakonakono gasho miiputudilo yombombanda itatu yakwatelwa momapekapeko. Hugunina, epekapeko ndika otali ulike/gandja oshiholelwa shomodela ndjoka oAcademic literacy tai vulu okulongwa opo yi kwatelemo eilongo lyiikwatelela kiilongwa osho yo komaitaalo nokeempumbwe dhaalongwa miiputudhilo yopombabda. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning (CHERTL), 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Julius, Lukas Homateni
- Date: 2021-04
- Subjects: Information literacy -- Study and teaching (Higher) -- Namibia , Academic writing -- Study and teaching -- Namibia , Qualitative research -- Methodology , Academic language -- Namibia , Information literacy -- Social aspects
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177293 , vital:42807 , 10.21504/10962/177293
- Description: The purpose of this study was to investigate academic literacy development lecturers’ conceptualisations of academic literacy and resultant pedagogical practices in academic development courses at three different Higher Education Institutional types in Namibia. The research sites were a Traditional University, a University of Technology and a Comprehensive University. The focus was to understand the extent to which the academics’ conceptions of academic literacy and the resultant pedagogical practices in the academic development courses at these three Higher Education Institutions (HEIs) facilitate epistemological access into students’ chosen fields of study. Bernstein’s Pedagogical theory (1990), Genre theory (1996) and Halliday’s Systemic Functional Linguistics (1978) were used as the study’s theoretical lenses and analytical framework. An interpretative paradigm and a qualitative case study design were employed as the research approach. Semi-structured interviews, classroom observations and documentary evidence were used to generate data. Research findings revealed a common (mis)conception of the nature of academic literacy, the resultant inadequate learning support offered to students in the selected academic literacy development courses, and a clear divorcing of academic literacy interventions from the students’ ‘home’ or mainstream disciplines at the three HEIs. The participants understood academic literacy from an autonomous position as a set of generic skills which could be taught outside of mainstream classes. Moreover, findings revealed that this understanding impacted on the design and assessments of all the academic literacy courses across the three universities under study. The study calls for a context sensitive model through which academic literacy acquisition can be scaffolded to meet the discipline-specific epistemological needs of the students. , Elalakano lyehokololoningomwa lyomapekapeko ndika olyo okukonakona ehumithokomeho lyomikalo dhokulesha nokushanga meilongngo lyopombada (oAcademic Literaci) maaputudhilongi, okukonakona omafatululo giisimanintsa moAcademic Literaci osho wo okutala iizemo yomikalo dhayooloka dhokulonga noku ilonga iilongwa yayooloka miiputudhilo yelongo lyopombada moNamibia. Omapekapeko ngaka oga li ga ningilwa miiputudhilo yomaukwatya ta ga landula; Oshiputudhiilo shopamudhigululwakalo, Oshiputudhilo shopaunongononi, nOshiputudilo shomailongo gaandjakana. Oshintsa shopokati shomapekapeko ngaka osho okuuva ko ondodo yowino osho wo euveko lyoAcademic Literaci maaputudhilongi nonkene euveko nontseyo ndjika tayi longithwa oku eta oshizemo tashi humitha komeho euveko lyopombanda lyaalongwa yomailongo geewino dhayooloka miiputudhilo itatu yelongo lyopombanda; shino otashi kwathele aalongwa yamone ontseyo ndjoka tayi ya kwathele meilongo lyawo. Omapekapeko ngano oga longitha omadhiladhiloukithi (eetheori) ga Bernstein’s Pedagogical theori (1990), Genre theori (1996) na Halliday’s Systemic Functional Linguistics theori (1978), mokufatulula nokundjandjukununa iizemo yomapekapeko. Omodela yokukonakona iizemo yongushu tayi ziilile maakonakonwa, oya tala ekonakono ndika onga oshintsa shopokati, oyo ya longithwa, opo ku monike uuyelele wothaathaa. Omikalo dha longifwa mokukonakona noku gongela uuyelele momapekapeko ngano ongaashi, eenkundathana dhayaali, omatalelo geetundi oshoyo omakonakono giinyanyangidhwa tayi kwandjangele nepekapeko ndika. Iizedjemo yepekapeko ndika otayi ulike kutya opena engwangwano montseyo nenge mefatululo lyuukwatya woAcademic Literaci, shoka sha eta enkundipalo meyambidhidho hali pewa aalongwa miilongwa yeewino dhayooloka. Shika otashi ulike kutya kapena etsokumwe pokati keenkambadhala tadhi ningwa kaapudhilongi dhokulonga oAcademic Litraci miilongwa ya yooloka mbyoka tayi ilongelwa kaalongwa miiputudhilo itatu yopombada. iizemmo yepekapeko olyo tuu mdika oya ulike wo kutya aalongwa mboka yaza komailongo ga yooloka oha yi ilongo nuudhigu opo ya pondole ondondo yomadhiladhilo gopombanda meilongo lyuukumwe. Mokukonakona euveko lyoAcademic Literaci, epekapeko ndika olya ndhindhilike kutya aakuthimbinga oyena euveko lyankundipala lyoterma ‘Academic Literaci,’ ano ya nyengwa okukwatakanitha oohedi dhopetameko ndhoka dhina oku ilongwa meikalekelo - ano pondje yiilongwa ikwao. Oshikwao, iizemo oya ulike kutya euveko ndika otali nwetha mo etungepo lyoAcademic Literaci onga oshilongwa, osho wo omakonakono gasho miiputudilo yombombanda itatu yakwatelwa momapekapeko. Hugunina, epekapeko ndika otali ulike/gandja oshiholelwa shomodela ndjoka oAcademic literacy tai vulu okulongwa opo yi kwatelemo eilongo lyiikwatelela kiilongwa osho yo komaitaalo nokeempumbwe dhaalongwa miiputudhilo yopombabda. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning (CHERTL), 2021
- Full Text:
- Date Issued: 2021-04
Synthesis of novel heterocyclic systems as potential inhibitors of HIV-1 enzymes
- Authors: Sekgota, Khethobole Cassius
- Date: 2020
- Subjects: Protease inhibitors , Heterocyclic compounds , HIV (Viruses) , Quinoline , Amides , Nuclear magnetic resonance , Antiretroviral agents , AIDS vaccines , Nitrobenzaldehyde , Propylphosphonic acid anhydride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146502 , vital:38531
- Description: This study has focussed on the application of Baylis-Hillman methodology in the development of efficient synthetic pathways to libraries of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones and indolizine-2-carboxamides and on an exploration of their medicinal potential. The approach to 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones involved a six-step pathway comprising: Baylis-Hillman reaction of 2-nitrobenzaldehyde derivatives and methyl acrylate to afford nitro-Baylis-Hillman adducts; thermal cyclisation of the adducts to give a range of 3-(acetoxymethyl)-2(1H)-quinolones in good to excellent yields; hydrolysis of the acetates; conversion of the resulting alcohols to the 3-chloromethyl analogues; amination; and, finally, acylation to afford the target amides. Variable temperature NMR methods were used to facilitate analysis of the ¹H and ¹³C NMR spectra which were complicated by internal rotation and cycloalkyl ring-flipping effects. On the other hand, the indolizine-2-carboxamides were obtained in several steps commencing with the Baylis-Hillman reaction of pyridine-2-carboxaldehyde and methyl acrylate. Thermal cyclisation of the Baylis-Hillman adduct afforded indolizine esters, hydrolysis of which gave the corresponding acids which served as precursors to the target indolizine-2-carboxamides. The final amidation step, however, proved to be particularly challenging. Various coupling strategies were explored to access indolizine-2-carboxamides. These included the use of 2,2,2-trifluoroethyl borate which showed limited promise, but propylphosphonic acid anhydride (T3P) proved to be the most effective coupling agent, permitting the formation of 24 novel indolizine-2-carboxamides from hydrazines, aliphatic amines and a range of heterocyclic amines. A high-field NMR-based kinetic study of the mechanism of the Baylis-Hillman reaction of pyridine-4-carboxaldehyde and methyl acrylate in the presence of 3-hydroxyquinuclidine in deuterated chloroform was initiated, reaction progress being followed by the automated collection of ¹H and DEPT 135 NMR spectra over ca. 24 hours using a high-field (600 MHz) NMR instrument. The results have provided critical new insights into the mechanism. NMR analysis has also been used to elucidate the multiplicity of signals associated with rotameric equilibria observed at ambient probe temperature. Variable temperature 1D- and 2D-NMR spectra were used to facilitate the unambiguous characterisation of the 2-quinolone benzamides and some of the indolizine-2-carboxamides. The 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones, together with selected precursors, and a number of the indolizine-2-carboxamides have been screened in vitro as potential HIV-1 enzyme inhibitors. A survey of the activity of the 2-quinolones against HIV-1 integrase, protease and reverse transcriptase revealed selective inhibition of HIV-1 integrase with the most active IN inhibitor, 3-[(cyclopentylamino)methyl-6-methoxy-2(1H)-quinolone 115e, producing residual enzyme activity of 40% at a concentration of 20 μM. Many of the 2-quinolones exhibited no significant cytotoxicity against HEK 293 cells at 20 μM concentrations. 3-[(N-Cyclohexylamino)methyl]-6-methoxy-2(1H)-quinolone 114e was the only compound to exhibit ant-plasmodial activity (55% pfLDH activity). The survey of indolizine-2-carboxamides also revealed encouraging inhibition against HIV-1 integrase. None of these compounds exhibited cytotoxicity at 20 μM against HEK 293 cells, while a number of them exhibited some activity against Plasmodium falciparum (3D7 strain) and Trypanosoma brucei. Selected indolizine-2-carboxamides exhibited significant anti-tubercular activity in the 7H9 CAS GLU Tx and 7H9 ADC GLU Tw media. In view of the inherent fluorescent character and biological potential of the synthesised indolizine-2-carboxamides, their photophysical properties were explored to establish their possible dual use as bio-imaging and therapeutic agents. The major absorption and corresponding emission bands, and the associated molar absorption coefficients (Ɛ) expressed in the form of log Ɛ were determined. Their high extinction coefficients, large Stokes shift and red-shifted emissions in the visible region indicate their potential for use as fluorophores.
- Full Text:
- Date Issued: 2020
- Authors: Sekgota, Khethobole Cassius
- Date: 2020
- Subjects: Protease inhibitors , Heterocyclic compounds , HIV (Viruses) , Quinoline , Amides , Nuclear magnetic resonance , Antiretroviral agents , AIDS vaccines , Nitrobenzaldehyde , Propylphosphonic acid anhydride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146502 , vital:38531
- Description: This study has focussed on the application of Baylis-Hillman methodology in the development of efficient synthetic pathways to libraries of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones and indolizine-2-carboxamides and on an exploration of their medicinal potential. The approach to 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones involved a six-step pathway comprising: Baylis-Hillman reaction of 2-nitrobenzaldehyde derivatives and methyl acrylate to afford nitro-Baylis-Hillman adducts; thermal cyclisation of the adducts to give a range of 3-(acetoxymethyl)-2(1H)-quinolones in good to excellent yields; hydrolysis of the acetates; conversion of the resulting alcohols to the 3-chloromethyl analogues; amination; and, finally, acylation to afford the target amides. Variable temperature NMR methods were used to facilitate analysis of the ¹H and ¹³C NMR spectra which were complicated by internal rotation and cycloalkyl ring-flipping effects. On the other hand, the indolizine-2-carboxamides were obtained in several steps commencing with the Baylis-Hillman reaction of pyridine-2-carboxaldehyde and methyl acrylate. Thermal cyclisation of the Baylis-Hillman adduct afforded indolizine esters, hydrolysis of which gave the corresponding acids which served as precursors to the target indolizine-2-carboxamides. The final amidation step, however, proved to be particularly challenging. Various coupling strategies were explored to access indolizine-2-carboxamides. These included the use of 2,2,2-trifluoroethyl borate which showed limited promise, but propylphosphonic acid anhydride (T3P) proved to be the most effective coupling agent, permitting the formation of 24 novel indolizine-2-carboxamides from hydrazines, aliphatic amines and a range of heterocyclic amines. A high-field NMR-based kinetic study of the mechanism of the Baylis-Hillman reaction of pyridine-4-carboxaldehyde and methyl acrylate in the presence of 3-hydroxyquinuclidine in deuterated chloroform was initiated, reaction progress being followed by the automated collection of ¹H and DEPT 135 NMR spectra over ca. 24 hours using a high-field (600 MHz) NMR instrument. The results have provided critical new insights into the mechanism. NMR analysis has also been used to elucidate the multiplicity of signals associated with rotameric equilibria observed at ambient probe temperature. Variable temperature 1D- and 2D-NMR spectra were used to facilitate the unambiguous characterisation of the 2-quinolone benzamides and some of the indolizine-2-carboxamides. The 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones, together with selected precursors, and a number of the indolizine-2-carboxamides have been screened in vitro as potential HIV-1 enzyme inhibitors. A survey of the activity of the 2-quinolones against HIV-1 integrase, protease and reverse transcriptase revealed selective inhibition of HIV-1 integrase with the most active IN inhibitor, 3-[(cyclopentylamino)methyl-6-methoxy-2(1H)-quinolone 115e, producing residual enzyme activity of 40% at a concentration of 20 μM. Many of the 2-quinolones exhibited no significant cytotoxicity against HEK 293 cells at 20 μM concentrations. 3-[(N-Cyclohexylamino)methyl]-6-methoxy-2(1H)-quinolone 114e was the only compound to exhibit ant-plasmodial activity (55% pfLDH activity). The survey of indolizine-2-carboxamides also revealed encouraging inhibition against HIV-1 integrase. None of these compounds exhibited cytotoxicity at 20 μM against HEK 293 cells, while a number of them exhibited some activity against Plasmodium falciparum (3D7 strain) and Trypanosoma brucei. Selected indolizine-2-carboxamides exhibited significant anti-tubercular activity in the 7H9 CAS GLU Tx and 7H9 ADC GLU Tw media. In view of the inherent fluorescent character and biological potential of the synthesised indolizine-2-carboxamides, their photophysical properties were explored to establish their possible dual use as bio-imaging and therapeutic agents. The major absorption and corresponding emission bands, and the associated molar absorption coefficients (Ɛ) expressed in the form of log Ɛ were determined. Their high extinction coefficients, large Stokes shift and red-shifted emissions in the visible region indicate their potential for use as fluorophores.
- Full Text:
- Date Issued: 2020
Formulation and characterisation of a combination captopril and hydrochlorothiazide microparticulate dosage form for paediatric use
- Chikukwa, Mellisa Tafadzwa Ruramai
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
Determination of nonlinear optical properties of phthalocyanine regioisomers using computational models
- Date: 2020
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Nonlinear optics , Nonlinear optical spectroscopy , Refraction
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166197 , vital:41337
- Description: This work investigates the effects of the nonlinear optical properties of four different constitutional isomers (C4h, C2v, Cs, and D2h) of a series of tetrasubstituted phthalocyanines (free-base 3-4-tert-butylphenoxyether phthalocyanines, free-base 4-4-tertbutylphenoxyether phthalocyanines, SnCl2 tetra substituted 3-4-tert-butylphenoxyether phthalocyanine, and SnCl2 tetra substituted 4-4-tert-butylphenoxyether phthalocyanine). The properties investigated were the real and imaginary components of the 3rd order hyperpolarizability, as well as the excited state absorption and refraction cross sections. The investigations were performed with a z-scan over a range of laser beam intensities. This work determined the imaginary component of the 3rd order hyperpolarizability for the free-base and SnCl2 3-4-tert-butylphenoxyether phthalocyanines and 4-4-tert-butylphenoxyether phthalocyanines to be highly dependent on the excited state cross sections. The refraction caused due to the real component of the 3rd order hyperpolarizability of the phthalocyanines was also investigated, however, the values found were strongly dependent on the laser beam intensity and the cause of this was investigated. A Five-level model was developed and run on GPGPU computing devices in order to isolate the absorption and refractive cross sections. Theeffects of the regio substitution on the excited state cross sections were also investigated, and the 1st singlet excited state and 1st triplet state absorption cross sections were calculated for all constitutional isomers. It was found that the symmetry of the constitutional isomers have a disproportionately large effect on the excited state absorption when compared to the ground state absorption. The nonlinear refractive properties of all constitutional isomers were also investigated, and the values of the parametric susceptibility are reported herein. The nonlinear refraction was found to have less effect than was seen in the nonlinear absorption. The 1st singlet excited state and 1st triplet state refractive cross sections of all constitutional isomer was determined. The results indicated that if more than one excited state was present and contributing to the nonlinear refraction, then more data than was collected here would be required. However, the 1st singlet excited state cross section were successfully determined for the free-base constitutional isomers. This work concluded that the region substitution affected the excited states more than the ground state.
- Full Text:
- Date Issued: 2020
- Date: 2020
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Nonlinear optics , Nonlinear optical spectroscopy , Refraction
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166197 , vital:41337
- Description: This work investigates the effects of the nonlinear optical properties of four different constitutional isomers (C4h, C2v, Cs, and D2h) of a series of tetrasubstituted phthalocyanines (free-base 3-4-tert-butylphenoxyether phthalocyanines, free-base 4-4-tertbutylphenoxyether phthalocyanines, SnCl2 tetra substituted 3-4-tert-butylphenoxyether phthalocyanine, and SnCl2 tetra substituted 4-4-tert-butylphenoxyether phthalocyanine). The properties investigated were the real and imaginary components of the 3rd order hyperpolarizability, as well as the excited state absorption and refraction cross sections. The investigations were performed with a z-scan over a range of laser beam intensities. This work determined the imaginary component of the 3rd order hyperpolarizability for the free-base and SnCl2 3-4-tert-butylphenoxyether phthalocyanines and 4-4-tert-butylphenoxyether phthalocyanines to be highly dependent on the excited state cross sections. The refraction caused due to the real component of the 3rd order hyperpolarizability of the phthalocyanines was also investigated, however, the values found were strongly dependent on the laser beam intensity and the cause of this was investigated. A Five-level model was developed and run on GPGPU computing devices in order to isolate the absorption and refractive cross sections. Theeffects of the regio substitution on the excited state cross sections were also investigated, and the 1st singlet excited state and 1st triplet state absorption cross sections were calculated for all constitutional isomers. It was found that the symmetry of the constitutional isomers have a disproportionately large effect on the excited state absorption when compared to the ground state absorption. The nonlinear refractive properties of all constitutional isomers were also investigated, and the values of the parametric susceptibility are reported herein. The nonlinear refraction was found to have less effect than was seen in the nonlinear absorption. The 1st singlet excited state and 1st triplet state refractive cross sections of all constitutional isomer was determined. The results indicated that if more than one excited state was present and contributing to the nonlinear refraction, then more data than was collected here would be required. However, the 1st singlet excited state cross section were successfully determined for the free-base constitutional isomers. This work concluded that the region substitution affected the excited states more than the ground state.
- Full Text:
- Date Issued: 2020
An evaluation of the cytotoxic activities of novel artemisinin derivatives: towards targeted therapies for triple-negative breast cancers (TNBC)
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
The current role of palm species Hyphaene Coriacea and Phoenix Reclanata in local livelihoods in the Zitundo area, southern Mozambique
- Authors: Martins, Angelina R O
- Date: 2020
- Subjects: Ilala palm -- Economic aspects -- Mozambique , Palms -- Economic aspects -- Mozambique , Non-timber forest products industry -- Mozambique , Sustainable development -- Mozambique , Conservation of natural resources -- Mozambique
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150613 , vital:38989
- Description: The majority of rural households in developing countries are heavily dependent on non-timber forest products (NTFPs) to fulfill much of their basic daily needs. In Mozambique more than 64% of the population lives in rural areas and depends heavily in the extraction of NTFPs to complement agricultural production. One substantial source of NTFPs are palm species. Palms are sources of food, building materials, cloth, ornaments, medicines, and are also used for cultural purposes. In southern Mozambique two important palms species used as NTFPs are Hyphaene coriacea and Phoenix reclinata. These two species provide an array of subsistence and commercial products. The sap, leaves and stems of these two palms are harvested by local people as sources of traditional beverages, weaving, roofing, fencing and furniture material as well as other household utensils. The effects (if any) of harvesting of these palm products on palm distribution, population structure, dynamics and viability have never been examined, and thus the sustainability of the practices and benefits flows to local livelihoods are unknow-n. Any effects harvesting effects may also be exacerbated by predicted climate change for the area. The present study aims to investigate the role of the palm species Hyphaene coriacea and Phoenix reclinata in the livelihoods of households in the Zitundo area, Matutuine district, southern Mozambique and under future climate scenarios. Specifically, this study: i) evaluates the abundance, population structure and harvesting selection of these species; ii) characterizes the ethnobotanical knowledge and use of the two species; iii) examines the local production and trade of palm wine in the area; iv) examines the contribution of palm income to livelihoods and income diversification in area; v) describes the local management practices and perceptions on palm productivity and abundance; and vi) models the current and future distribution of the these palm species in the area. To evaluate the abundance, population structure and stability of these two palm species a population census was carried out, and the size class distribution, Simpson index of dominance, permutation index and the quotient between successive size classes were calculated. I further calculated the preference ratio for specific size classes. Additionally a questionnaire survey was conducted with 179 randomly selected households from the 16 villages in the study area to characterize the ethnobotanical knowledge and use of these two species, as well as to examine the contribution of palm income to livelihoods and diversification. Standard ethnobotanical indices were used as measures of each palm species use and knowledge while principal component analysis and cluster analysis were applied to highlight the livelihood patterns and the role of diversification and of palm income in local livelihoods. Structured interviews with 37 palm tappers were additionally used to examine the local production and trade of palm wine in the area, while both the household survey and palm tappers interviews, were employed to investigate the local management practices and perceptions on palms productivity and abundance. Maxent Software was used to model the current and future under climate change distribution of the two palm species. Hyphaene coriacea was more abundant than Phoenix reclinata. Both species exhibited steep negative slopes in the regression analyses of size class distribution, indicating the presence of more individuals in shorter size classes. Although there was a dominance of shorter over taller size classes, limited recruitment was observed through low stem densities of seedlings and juveniles compared to the 1-50 cm size class The Simpson index of dominance, the permutation index, and the fluctuating quotients between the consecutive size classes showed a level of instability in both populations. Hyphaene coriacea appeared to be more resilient to tapping than Phoenix reclinata as showed by the higher rate of stem survival after tapping. Hyphaene coriacea was favored for tapping compared to Phoenix reclinata. The most preferred size class to tap for both species was between 101cm and 150 cm. Currently the distribution of Hyphaene coriacea and Phoenix reclinata was mostly confined to the eastern side of the study area. Most of the area was predicted as unsuitable for both palm species, with less than six percent predicted to be suitable or higher. The occurrence of both species appeared to be influenced mostly by water related variables, such as precipitation, and distance to rivers and distance to water bodies. The habitat suitability for Hyphaene coriacea was predicted to increase under future climate conditions scenarios, while little variation was predicted for Phoenix reclinata distribution. The knowledge about the uses of these two palm species was widespread in the area, although only 32% of respondents were engaged in palm exploitation. Thirteen palm products were exploited, with palm wine production from the sap of both palms being the dominant activity, followed by broom production from Phoenix reclinata stems and basket production from Hyphaene coriacea leaves. The cultural importance of these species included the production of anklets and skirts used during traditional dances and the use of palm wine in the traditional ritual of libation. Palm tapping was practiced year round in five of the sixteen villages in the area. Palm tapping was an important livelihood activity, contributing over 80% of tappers’ total annual income, and tappers earned up to three times more than the national minimum wage for the agricultural and forestry sector. Palm wine was also a highly commercial commodity in Zitundo area, with an average commercialization index above 60%. The income from palm wine sales showed an important role in mitigating the level of poverty in the area. Palm income accounted for over 60% reduction on poverty incidence among palm tappers. Households in Zitundo further engaged in some level of livelihood diversification. The majority of households adopted a wage-based strategy, although this strategy was among the less remunerative in terms of per capita cash income. A palm-based livelihood strategy, although adopted only by 11% of households, was one of the most remunerative strategies. Palm income played a vital role in enhancing household livelihoods and mitigating poverty in the area as shown by the lower poverty incidences among households engaged in the palm-based livelihood strategy than alternatives strategies. The village of household residency, along with household demographic and socio-economic characteristics appeared to determine the knowledge and exploitation level of palms as well as a households’ choice of livelihood strategy, level of palm wine returns, commercialization index and palm income dependency. The importance of palms in local livelihoods and poverty alleviation needs greater acknowledgement by government and development agencies in the area. Palm wine, broom and basket production have a high potential for income generation, and therefore should be included in future local development policies and poverty reduction strategies. Although palms are an open access resource in Zitundo area, the perception is that they are abundant and that tapping does not have many detrimental effects. However, this study found some negative impacts of tapping on the recruitment of both palms species. The inclusion of palm products in future development programs and poverty reduction strategies will require the design of participatory conservation and management strategies that involve all palm users groups and others stakeholders and include long-term participatory monitoring of the effect of palm use on the populations.
- Full Text:
- Date Issued: 2020
- Authors: Martins, Angelina R O
- Date: 2020
- Subjects: Ilala palm -- Economic aspects -- Mozambique , Palms -- Economic aspects -- Mozambique , Non-timber forest products industry -- Mozambique , Sustainable development -- Mozambique , Conservation of natural resources -- Mozambique
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150613 , vital:38989
- Description: The majority of rural households in developing countries are heavily dependent on non-timber forest products (NTFPs) to fulfill much of their basic daily needs. In Mozambique more than 64% of the population lives in rural areas and depends heavily in the extraction of NTFPs to complement agricultural production. One substantial source of NTFPs are palm species. Palms are sources of food, building materials, cloth, ornaments, medicines, and are also used for cultural purposes. In southern Mozambique two important palms species used as NTFPs are Hyphaene coriacea and Phoenix reclinata. These two species provide an array of subsistence and commercial products. The sap, leaves and stems of these two palms are harvested by local people as sources of traditional beverages, weaving, roofing, fencing and furniture material as well as other household utensils. The effects (if any) of harvesting of these palm products on palm distribution, population structure, dynamics and viability have never been examined, and thus the sustainability of the practices and benefits flows to local livelihoods are unknow-n. Any effects harvesting effects may also be exacerbated by predicted climate change for the area. The present study aims to investigate the role of the palm species Hyphaene coriacea and Phoenix reclinata in the livelihoods of households in the Zitundo area, Matutuine district, southern Mozambique and under future climate scenarios. Specifically, this study: i) evaluates the abundance, population structure and harvesting selection of these species; ii) characterizes the ethnobotanical knowledge and use of the two species; iii) examines the local production and trade of palm wine in the area; iv) examines the contribution of palm income to livelihoods and income diversification in area; v) describes the local management practices and perceptions on palm productivity and abundance; and vi) models the current and future distribution of the these palm species in the area. To evaluate the abundance, population structure and stability of these two palm species a population census was carried out, and the size class distribution, Simpson index of dominance, permutation index and the quotient between successive size classes were calculated. I further calculated the preference ratio for specific size classes. Additionally a questionnaire survey was conducted with 179 randomly selected households from the 16 villages in the study area to characterize the ethnobotanical knowledge and use of these two species, as well as to examine the contribution of palm income to livelihoods and diversification. Standard ethnobotanical indices were used as measures of each palm species use and knowledge while principal component analysis and cluster analysis were applied to highlight the livelihood patterns and the role of diversification and of palm income in local livelihoods. Structured interviews with 37 palm tappers were additionally used to examine the local production and trade of palm wine in the area, while both the household survey and palm tappers interviews, were employed to investigate the local management practices and perceptions on palms productivity and abundance. Maxent Software was used to model the current and future under climate change distribution of the two palm species. Hyphaene coriacea was more abundant than Phoenix reclinata. Both species exhibited steep negative slopes in the regression analyses of size class distribution, indicating the presence of more individuals in shorter size classes. Although there was a dominance of shorter over taller size classes, limited recruitment was observed through low stem densities of seedlings and juveniles compared to the 1-50 cm size class The Simpson index of dominance, the permutation index, and the fluctuating quotients between the consecutive size classes showed a level of instability in both populations. Hyphaene coriacea appeared to be more resilient to tapping than Phoenix reclinata as showed by the higher rate of stem survival after tapping. Hyphaene coriacea was favored for tapping compared to Phoenix reclinata. The most preferred size class to tap for both species was between 101cm and 150 cm. Currently the distribution of Hyphaene coriacea and Phoenix reclinata was mostly confined to the eastern side of the study area. Most of the area was predicted as unsuitable for both palm species, with less than six percent predicted to be suitable or higher. The occurrence of both species appeared to be influenced mostly by water related variables, such as precipitation, and distance to rivers and distance to water bodies. The habitat suitability for Hyphaene coriacea was predicted to increase under future climate conditions scenarios, while little variation was predicted for Phoenix reclinata distribution. The knowledge about the uses of these two palm species was widespread in the area, although only 32% of respondents were engaged in palm exploitation. Thirteen palm products were exploited, with palm wine production from the sap of both palms being the dominant activity, followed by broom production from Phoenix reclinata stems and basket production from Hyphaene coriacea leaves. The cultural importance of these species included the production of anklets and skirts used during traditional dances and the use of palm wine in the traditional ritual of libation. Palm tapping was practiced year round in five of the sixteen villages in the area. Palm tapping was an important livelihood activity, contributing over 80% of tappers’ total annual income, and tappers earned up to three times more than the national minimum wage for the agricultural and forestry sector. Palm wine was also a highly commercial commodity in Zitundo area, with an average commercialization index above 60%. The income from palm wine sales showed an important role in mitigating the level of poverty in the area. Palm income accounted for over 60% reduction on poverty incidence among palm tappers. Households in Zitundo further engaged in some level of livelihood diversification. The majority of households adopted a wage-based strategy, although this strategy was among the less remunerative in terms of per capita cash income. A palm-based livelihood strategy, although adopted only by 11% of households, was one of the most remunerative strategies. Palm income played a vital role in enhancing household livelihoods and mitigating poverty in the area as shown by the lower poverty incidences among households engaged in the palm-based livelihood strategy than alternatives strategies. The village of household residency, along with household demographic and socio-economic characteristics appeared to determine the knowledge and exploitation level of palms as well as a households’ choice of livelihood strategy, level of palm wine returns, commercialization index and palm income dependency. The importance of palms in local livelihoods and poverty alleviation needs greater acknowledgement by government and development agencies in the area. Palm wine, broom and basket production have a high potential for income generation, and therefore should be included in future local development policies and poverty reduction strategies. Although palms are an open access resource in Zitundo area, the perception is that they are abundant and that tapping does not have many detrimental effects. However, this study found some negative impacts of tapping on the recruitment of both palms species. The inclusion of palm products in future development programs and poverty reduction strategies will require the design of participatory conservation and management strategies that involve all palm users groups and others stakeholders and include long-term participatory monitoring of the effect of palm use on the populations.
- Full Text:
- Date Issued: 2020
CO2-induced woody thickening depends strongly on interacting abiotic and biotic factors
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text:
- Date Issued: 2020
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text:
- Date Issued: 2020
Localising the global: the use of a postmodernist aesthetic in the fiction of Alain Mabanckou
- Authors: Ngulube, Innocent Akilimale
- Date: 2020
- Subjects: Mabanckou, Alain, 1966- , Mabanckou, Alain, 1966- -- Blue, white, red , Mabanckou, Alain, 1966- -- African psycho , Mabanckou, Alain, 1966- -- Broken glass , Mabanckou, Alain, 1966- -- Memoirs of a porcupine , Mabanckou, Alain, 1966- -- The Lights of Pointe-Noire , Mabanckou, Alain, 1966- -- Tomorrow I'll be twenty , Mabanckou, Alain, 1966- Black bazaar , Postcolonialism in literature , African fiction (French) -- History and criticism , Postmodernism (Literature)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167153 , vital:41442
- Description: This thesis explores the use of a postmodernist aesth etic in Alain Mabanckou’s oeuvre, namely Blue White Red, African Psycho, Broken Glass, Memoirs of a Porcupine, Black Bazaar, Tomorrow I’ll Be Twenty, The Lights of Pointe-Noire, and Black Moses. In particular, I show how and why this Afrodiasporic author localises strategies associated with Western postmodernist writing in an African postcolonial context. My central argument is that if postmodernism is a critique of modernity in the West, then it must also be a respon se to enforced modernity in the African postcolonial context. In mounting this argument, I conduct a close reading of Mabanckou’s novels from within the theoretical frameworks of postmodernism and postcolonialism. I demonstrate that Mabanckou’s writing adu mbrates the possibility of a postcolonial postmodernism. Since he is a French-Congolese citizen, his writing evinces aesthetic glocalisation. That is, as a postcolonial writer, he conceives of, and inflects, postmodernism differently from a Western writer, for his experiences of and responses to modernity differ from the latter’s. Far from replicating a politics of disillusionment and despair that informs, even characterises, Western postmodernist fiction, Mabanckou invests hi s African postcolonial writing with a politics of decolonis ation which problematises the effects of enforced modernity. Postmodernism, in other words, accords Mabanckou an ambivalent position from which he interrogates both Western modernity and its African version. Significantly, in this regard, Mabanckou’s writing presents both an extension of and a departure from the pioneering influence of the first generation of African writers such as Chinua Achebe, Ngugi wa Thiong’o, and Wole Soyinka.
- Full Text:
- Date Issued: 2020
- Authors: Ngulube, Innocent Akilimale
- Date: 2020
- Subjects: Mabanckou, Alain, 1966- , Mabanckou, Alain, 1966- -- Blue, white, red , Mabanckou, Alain, 1966- -- African psycho , Mabanckou, Alain, 1966- -- Broken glass , Mabanckou, Alain, 1966- -- Memoirs of a porcupine , Mabanckou, Alain, 1966- -- The Lights of Pointe-Noire , Mabanckou, Alain, 1966- -- Tomorrow I'll be twenty , Mabanckou, Alain, 1966- Black bazaar , Postcolonialism in literature , African fiction (French) -- History and criticism , Postmodernism (Literature)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167153 , vital:41442
- Description: This thesis explores the use of a postmodernist aesth etic in Alain Mabanckou’s oeuvre, namely Blue White Red, African Psycho, Broken Glass, Memoirs of a Porcupine, Black Bazaar, Tomorrow I’ll Be Twenty, The Lights of Pointe-Noire, and Black Moses. In particular, I show how and why this Afrodiasporic author localises strategies associated with Western postmodernist writing in an African postcolonial context. My central argument is that if postmodernism is a critique of modernity in the West, then it must also be a respon se to enforced modernity in the African postcolonial context. In mounting this argument, I conduct a close reading of Mabanckou’s novels from within the theoretical frameworks of postmodernism and postcolonialism. I demonstrate that Mabanckou’s writing adu mbrates the possibility of a postcolonial postmodernism. Since he is a French-Congolese citizen, his writing evinces aesthetic glocalisation. That is, as a postcolonial writer, he conceives of, and inflects, postmodernism differently from a Western writer, for his experiences of and responses to modernity differ from the latter’s. Far from replicating a politics of disillusionment and despair that informs, even characterises, Western postmodernist fiction, Mabanckou invests hi s African postcolonial writing with a politics of decolonis ation which problematises the effects of enforced modernity. Postmodernism, in other words, accords Mabanckou an ambivalent position from which he interrogates both Western modernity and its African version. Significantly, in this regard, Mabanckou’s writing presents both an extension of and a departure from the pioneering influence of the first generation of African writers such as Chinua Achebe, Ngugi wa Thiong’o, and Wole Soyinka.
- Full Text:
- Date Issued: 2020
Understanding a West African recreational fishery as a complex social-ecological system – a case study of the fishery for giant African threadfin Polydactylus quadrifilis (Cuvier, 1829) in the Kwanza Estuary, Angola
- Authors: Butler, Edward C
- Date: 2020
- Subjects: Cuanza River (Angola) , Fishing -- Angola , Polynemidae , Fishes -- Angola -- Ecology
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146688 , vital:38548
- Description: Despite increasing global recognition of the importance of recreational fisheries, their management largely remains poor. This is because they exhibit unique human-nature relationships and are nested within complex social-ecological systems (SESs). Recreational fisheries in the developing world have large potential for socio-economic development, but are generally underappreciated, in terms of their value and their impact, and are poorly governed. This is particularly concerning as they are highly complex and often compete for resources with dependent artisanal and subsistence fisheries. Developing world recreational fishery SESs are not well understood and present an important research gap for improved governance. The general aim of this thesis was to explore the recreational fishery targeting Polydactylus quadrifilis on the Kwanza Estuary, Angola, and provide context for how managers should approach recreational fisheries in the developing world and in Africa. To do this, the recreational fishery SES was explored using a combination of methodologies including those characteristic of traditional fisheries science, and new methods involving biology, sociology, and economics. The thesis contains an introductory chapter, a chapter describing the background, study area and study species, five data chapters and a discussion chapter. Chapter 3 aimed to investigate the reproductive style of P. quadrifilis. Results identified the species as a protandrous hermaphrodite. Evidence to suggest this included degenerating testicular tissue and the presence of early developing ovarian tissues in transitional individuals. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. Owing to the species’ reliance on large highly fecund females for reproduction, it is likely that P. quadrifilis will be sensitive to fisheries that target larger individuals, such as trophy recreational fisheries and line fisheries within other sectors. Chapter 4 aimed to investigate alternative methods for adequately describing the growth of P. quadrifilis individuals belonging to either one of two distinct hypothetical life-history pathways: pathway I (‘changers’) – initial maturation as a primary male followed by a sex change to female; pathway II (‘non-changers’) – initial maturation as a male fish with no subsequent sex change, using von Bertalanffy Growth Functions (VBGFs). Other specific objectives included determining the size- and age-at-maturity and size- and age-at-sex-change for P. quadrifilis. Otolith aging revealed rapid growth and early maturation (L50 = 399.2 mm FL, A50 = 1.50 years) and sex change occurred over a wide size (790–1125 mm FL) and age (3–8 years) range. There was strong evidence for partial protandry in P. quadrifilis with several extremely old male fish (up to 22 years) observed in the population. When compared to the conventional model produced for the entire population, there were significant differences in the models for the ‘non-changers’ (LRT, p < 0.01) and their parameters L∞ (full model = 130.8, ‘non-changers’ = 113.3, p < 0.01), k (0.32, 0.44, p < 0.01) and t0 (0.23, 0.43, p = 0.03) in the first approach and the models (LRT, p < 0.01) and their L∞ (‘changers’ = 113.7, p < 0.01) values in the second approach. This suggests that utilising conventional modelling techniques may be inappropriate for the stock assessment and management of P. quadrifilis and, potentially, other sequentially hermaphroditic fishery species. Chapter 5 aimed to assess the sensitivity of P. quadrifilis to recreational C&R within the foreign recreational fishery using a rapid assessment approach. To do this, a number of C&R variables including fight time, air exposure, hook placement, hooking injury, total time of the stress event, river depth and angling method were measured and related to two indicators of fish health and survival – the physiological stress indicators blood glucose and blood lactate concentration and reflex action mortality predictors (RAMPs). Air exposure was identified as a major contributor to motor impairment (Cumulative Link Model: p < 0.01) and fight time was an important contributor to motor impairment via its interaction with air exposure (Cumulative Link Model: p = 0.02). Handling practices appear to be particularly important for larger individuals as fish size was positively correlated with air exposure (Pearson’s r coefficient = 0.41, p < 0.01) and fight times (0.88, p < 0.01). The findings suggest that recreational C&R may result in mortalities directly, via C&R, and indirectly, via predation, and several recommendations were made for best practice. Chapter 6 aimed to assess the direct economic contribution of the recreational fishery for Polydactylus quadrifilis on the Kwanza Estuary. Results indicated that the recreational fishery for contributed significantly to the economy of an area that would otherwise likely receive little external input ($282 054 per four-month fishing season). However, high rates of economic leakage from the study area were identified (58.7%–92.9% of locally spent revenue) and were attributed to the sourcing of lodge supplies, services and staff outside of the local area and the repatriation of profit by foreign business owners. Capacity building within the local community is likely required to develop ‘linkages’ between the local community and the recreational fishery. Greater community involvement in the fishery is suggested to incentivise the protection of recreationally important fishery species and their associated ecosystems. Chapter 7 aimed to investigate the resource user groups involved within the SES. Results illustrated that artisanal and domestic recreational anglers are well-established and are characterised by long histories of participation. The artisanal fishery was highly valued as a source of livelihoods for the local community. Artisanal fishers were eager for involvement in the recreational sector, through the chartering of their vessels, due to the attractiveness of extra earnings. Both recreational and artisanal fishers reported recent decreases in P. quadrifilis catch and anticipated further declines. Domestic recreational anglers appeared to be highly consumptive in their use of the fishery and C&R angling was uncommon. User conflict may be problematic for future management as recreational anglers perceived the artisanal gill-net fishery to be a threat towards P. quadrifilis stocks. In conclusion, the open-access nature of the fishery was identified as the most pertinent threat to its sustainability and likely needs to be addressed. Potential solutions involve offering users the opportunity to purchase access rights (e.g. day permits), thus initiating the concept that users must pay for their use of public resources. Management should aim to protect large female fish due to their increased reproductive value and worth as trophy fish. Thus, C&R angling is likely to be an important interaction between users and the resource. However, angler behaviour will need to be manipulated to promote C&R and minimise C&R-related mortalities. Solutions include angler educational drives and interventions and the implementation of competitive C&R-only angling. Foreign recreational fisheries, although touted as potential ecotourism ventures, will only succeed in improving the lives of local people if they fully integrate the community into the operation of the fishery.
- Full Text:
- Date Issued: 2020
- Authors: Butler, Edward C
- Date: 2020
- Subjects: Cuanza River (Angola) , Fishing -- Angola , Polynemidae , Fishes -- Angola -- Ecology
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146688 , vital:38548
- Description: Despite increasing global recognition of the importance of recreational fisheries, their management largely remains poor. This is because they exhibit unique human-nature relationships and are nested within complex social-ecological systems (SESs). Recreational fisheries in the developing world have large potential for socio-economic development, but are generally underappreciated, in terms of their value and their impact, and are poorly governed. This is particularly concerning as they are highly complex and often compete for resources with dependent artisanal and subsistence fisheries. Developing world recreational fishery SESs are not well understood and present an important research gap for improved governance. The general aim of this thesis was to explore the recreational fishery targeting Polydactylus quadrifilis on the Kwanza Estuary, Angola, and provide context for how managers should approach recreational fisheries in the developing world and in Africa. To do this, the recreational fishery SES was explored using a combination of methodologies including those characteristic of traditional fisheries science, and new methods involving biology, sociology, and economics. The thesis contains an introductory chapter, a chapter describing the background, study area and study species, five data chapters and a discussion chapter. Chapter 3 aimed to investigate the reproductive style of P. quadrifilis. Results identified the species as a protandrous hermaphrodite. Evidence to suggest this included degenerating testicular tissue and the presence of early developing ovarian tissues in transitional individuals. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. Owing to the species’ reliance on large highly fecund females for reproduction, it is likely that P. quadrifilis will be sensitive to fisheries that target larger individuals, such as trophy recreational fisheries and line fisheries within other sectors. Chapter 4 aimed to investigate alternative methods for adequately describing the growth of P. quadrifilis individuals belonging to either one of two distinct hypothetical life-history pathways: pathway I (‘changers’) – initial maturation as a primary male followed by a sex change to female; pathway II (‘non-changers’) – initial maturation as a male fish with no subsequent sex change, using von Bertalanffy Growth Functions (VBGFs). Other specific objectives included determining the size- and age-at-maturity and size- and age-at-sex-change for P. quadrifilis. Otolith aging revealed rapid growth and early maturation (L50 = 399.2 mm FL, A50 = 1.50 years) and sex change occurred over a wide size (790–1125 mm FL) and age (3–8 years) range. There was strong evidence for partial protandry in P. quadrifilis with several extremely old male fish (up to 22 years) observed in the population. When compared to the conventional model produced for the entire population, there were significant differences in the models for the ‘non-changers’ (LRT, p < 0.01) and their parameters L∞ (full model = 130.8, ‘non-changers’ = 113.3, p < 0.01), k (0.32, 0.44, p < 0.01) and t0 (0.23, 0.43, p = 0.03) in the first approach and the models (LRT, p < 0.01) and their L∞ (‘changers’ = 113.7, p < 0.01) values in the second approach. This suggests that utilising conventional modelling techniques may be inappropriate for the stock assessment and management of P. quadrifilis and, potentially, other sequentially hermaphroditic fishery species. Chapter 5 aimed to assess the sensitivity of P. quadrifilis to recreational C&R within the foreign recreational fishery using a rapid assessment approach. To do this, a number of C&R variables including fight time, air exposure, hook placement, hooking injury, total time of the stress event, river depth and angling method were measured and related to two indicators of fish health and survival – the physiological stress indicators blood glucose and blood lactate concentration and reflex action mortality predictors (RAMPs). Air exposure was identified as a major contributor to motor impairment (Cumulative Link Model: p < 0.01) and fight time was an important contributor to motor impairment via its interaction with air exposure (Cumulative Link Model: p = 0.02). Handling practices appear to be particularly important for larger individuals as fish size was positively correlated with air exposure (Pearson’s r coefficient = 0.41, p < 0.01) and fight times (0.88, p < 0.01). The findings suggest that recreational C&R may result in mortalities directly, via C&R, and indirectly, via predation, and several recommendations were made for best practice. Chapter 6 aimed to assess the direct economic contribution of the recreational fishery for Polydactylus quadrifilis on the Kwanza Estuary. Results indicated that the recreational fishery for contributed significantly to the economy of an area that would otherwise likely receive little external input ($282 054 per four-month fishing season). However, high rates of economic leakage from the study area were identified (58.7%–92.9% of locally spent revenue) and were attributed to the sourcing of lodge supplies, services and staff outside of the local area and the repatriation of profit by foreign business owners. Capacity building within the local community is likely required to develop ‘linkages’ between the local community and the recreational fishery. Greater community involvement in the fishery is suggested to incentivise the protection of recreationally important fishery species and their associated ecosystems. Chapter 7 aimed to investigate the resource user groups involved within the SES. Results illustrated that artisanal and domestic recreational anglers are well-established and are characterised by long histories of participation. The artisanal fishery was highly valued as a source of livelihoods for the local community. Artisanal fishers were eager for involvement in the recreational sector, through the chartering of their vessels, due to the attractiveness of extra earnings. Both recreational and artisanal fishers reported recent decreases in P. quadrifilis catch and anticipated further declines. Domestic recreational anglers appeared to be highly consumptive in their use of the fishery and C&R angling was uncommon. User conflict may be problematic for future management as recreational anglers perceived the artisanal gill-net fishery to be a threat towards P. quadrifilis stocks. In conclusion, the open-access nature of the fishery was identified as the most pertinent threat to its sustainability and likely needs to be addressed. Potential solutions involve offering users the opportunity to purchase access rights (e.g. day permits), thus initiating the concept that users must pay for their use of public resources. Management should aim to protect large female fish due to their increased reproductive value and worth as trophy fish. Thus, C&R angling is likely to be an important interaction between users and the resource. However, angler behaviour will need to be manipulated to promote C&R and minimise C&R-related mortalities. Solutions include angler educational drives and interventions and the implementation of competitive C&R-only angling. Foreign recreational fisheries, although touted as potential ecotourism ventures, will only succeed in improving the lives of local people if they fully integrate the community into the operation of the fishery.
- Full Text:
- Date Issued: 2020
Between nationalism and transnationalism: entanglements of history, individual narrative, and memory in diaspora spaces in selected transnational fiction
- Authors: Bosman, Sean James
- Date: 2020
- Subjects: Literature and transnationalism , Gurnah, Abdulrazak, 1948- , Gurnah, Abdulrazak, 1948- -- By the sea , Gurnah, Abdulrazak, 1948- -- Gravel heart , Nguyen, Viet Thanh, 1971- , Nguyen, Viet Thanh, 1971- -- The sympathizer , Nguyen, Viet Thanh, 1971- -- The refugees , Urrea, Luis Alberto , Urrea, Luis Alberto -- The house of broken angels , Urrea, Luis Alberto -- The water museum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140932 , vital:37930
- Description: This thesis offers close readings and a comparative analysis of selected works by Abdulrazak Gurnah, Viet Thanh Nguyen, and Luis Alberto Urrea. The selected primary texts used are Gurnah’s By the Sea (2000) and Gravel Heart (2017), Nguyen’s The Sympathizer (2015) and The Refugees (2017), and Urrea’s The Water Museum (2015) and The House of Broken Angels (2018). Analyses are informed by a conceptual framework that draws on critical works by Avtar Brah, J. U. Jacobs, Sarah Nuttall, Homi K. Bhabha, Judith Butler, Stuart Hall, Paul Ricoeur, Viet Thanh Nguyen, and Christopher B. Patterson. These theories are deployed to analyse how the selected works engage with the entanglements of history, individual narratives, and memory in the diaspora spaces they articulate. The thesis argues that the selected works indicate an emerging subgenre within the broader category of transnational literature. This subgenre rejects disempowering interpolations of transnational identities. Instead, it prioritises ethical forms of memory. These acknowledge that transnational subjects share at least partial accountability for the precarity they experience in diaspora spaces. The selected literature limns how this may be accomplished by rejecting the label of victim. In so doing, the selected literature also suggests that the elevation of transnationals to full ethical agency would enable them to exercise power in their diaspora spaces. All three authorial projects studied here also give rise to uncomfortable juxtapositions that suggest a mounting fear that, as nationalisms become more pronounced in the UK and the USA, transnationals may have to re-experience conditions from which they have already fled. The thesis concludes by identifying four additional areas of confluence amongst the selected literature worthy of future study.
- Full Text:
- Date Issued: 2020
- Authors: Bosman, Sean James
- Date: 2020
- Subjects: Literature and transnationalism , Gurnah, Abdulrazak, 1948- , Gurnah, Abdulrazak, 1948- -- By the sea , Gurnah, Abdulrazak, 1948- -- Gravel heart , Nguyen, Viet Thanh, 1971- , Nguyen, Viet Thanh, 1971- -- The sympathizer , Nguyen, Viet Thanh, 1971- -- The refugees , Urrea, Luis Alberto , Urrea, Luis Alberto -- The house of broken angels , Urrea, Luis Alberto -- The water museum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140932 , vital:37930
- Description: This thesis offers close readings and a comparative analysis of selected works by Abdulrazak Gurnah, Viet Thanh Nguyen, and Luis Alberto Urrea. The selected primary texts used are Gurnah’s By the Sea (2000) and Gravel Heart (2017), Nguyen’s The Sympathizer (2015) and The Refugees (2017), and Urrea’s The Water Museum (2015) and The House of Broken Angels (2018). Analyses are informed by a conceptual framework that draws on critical works by Avtar Brah, J. U. Jacobs, Sarah Nuttall, Homi K. Bhabha, Judith Butler, Stuart Hall, Paul Ricoeur, Viet Thanh Nguyen, and Christopher B. Patterson. These theories are deployed to analyse how the selected works engage with the entanglements of history, individual narratives, and memory in the diaspora spaces they articulate. The thesis argues that the selected works indicate an emerging subgenre within the broader category of transnational literature. This subgenre rejects disempowering interpolations of transnational identities. Instead, it prioritises ethical forms of memory. These acknowledge that transnational subjects share at least partial accountability for the precarity they experience in diaspora spaces. The selected literature limns how this may be accomplished by rejecting the label of victim. In so doing, the selected literature also suggests that the elevation of transnationals to full ethical agency would enable them to exercise power in their diaspora spaces. All three authorial projects studied here also give rise to uncomfortable juxtapositions that suggest a mounting fear that, as nationalisms become more pronounced in the UK and the USA, transnationals may have to re-experience conditions from which they have already fled. The thesis concludes by identifying four additional areas of confluence amongst the selected literature worthy of future study.
- Full Text:
- Date Issued: 2020
A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University
- Authors: Tsope, Lindiwe
- Date: 2021-04
- Subjects: AIDS (Disease) South Africa Makhanda , HIV infections South Africa Makhanda , College students Health and hygiene South Africa Makhanda , Universities and colleges South Africa Makhanda Employees Health and hygiene , Stigma (Social psychology) , AIDS (Disease) Social aspects South Africa Makhanda , HIV infections Social aspects South Africa Makhanda , AIDS (Disease) Psychological aspects , HIV infections Psychological aspects , Health counseling South Africa Makhanda , Discourse analysis, Narrative
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/176894 , vital:42769 , 10.21504/10962/176894
- Description: A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University Research on HIV and AIDS in university settings, especially research exploring the experience of living with the disease, has been minimal. As a response to the knowledge and research gaps, this thesis is a qualitative study involving students and staff living with HIV (LWH) and accessing treatment (ART) at the Rhodes University Health Care Centre. This study explored the personal and social symbolisms as well as meanings attached to living with HIV, through in-depth interviews with ten students and staff living with HIV, all purposively sampled and recruited through the Rhodes University Health Care Centre. Using social constructionism, symbolic interactionism and the theory of biographical disruption, the narratives revealed a positive and inspirational side of living with HIV and AIDS – especially emphasizing that PLWHA do not have to surrender to the deadly narrative of the disease. It became evident that stigma, both internal and external, largely influences illness narratives. Furthermore, the study revealed the social reconstruction of life narratives both in order to understand the illness in terms of past social experiences and to reaffirm the impression that life has a course and the self has a purpose. All participants found that accessing treatment from the Rhodes University Health Care Centre positively influenced their experiences of adherence and reconstruction of narratives. The study indicates that HIV-related interventions in place at the university need to pay more attention to the psychosocial needs of PLWH, involvement of PWLH, as well as keeping up with the continuously changing global HIV narrative. The study argues for more attention to in-depth experiences and personal narratives in HIV and AIDS, and PLWHA education at Rhodes University. , Thesis (PhD) -- Humanities, Department of Sociology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Tsope, Lindiwe
- Date: 2021-04
- Subjects: AIDS (Disease) South Africa Makhanda , HIV infections South Africa Makhanda , College students Health and hygiene South Africa Makhanda , Universities and colleges South Africa Makhanda Employees Health and hygiene , Stigma (Social psychology) , AIDS (Disease) Social aspects South Africa Makhanda , HIV infections Social aspects South Africa Makhanda , AIDS (Disease) Psychological aspects , HIV infections Psychological aspects , Health counseling South Africa Makhanda , Discourse analysis, Narrative
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/176894 , vital:42769 , 10.21504/10962/176894
- Description: A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University Research on HIV and AIDS in university settings, especially research exploring the experience of living with the disease, has been minimal. As a response to the knowledge and research gaps, this thesis is a qualitative study involving students and staff living with HIV (LWH) and accessing treatment (ART) at the Rhodes University Health Care Centre. This study explored the personal and social symbolisms as well as meanings attached to living with HIV, through in-depth interviews with ten students and staff living with HIV, all purposively sampled and recruited through the Rhodes University Health Care Centre. Using social constructionism, symbolic interactionism and the theory of biographical disruption, the narratives revealed a positive and inspirational side of living with HIV and AIDS – especially emphasizing that PLWHA do not have to surrender to the deadly narrative of the disease. It became evident that stigma, both internal and external, largely influences illness narratives. Furthermore, the study revealed the social reconstruction of life narratives both in order to understand the illness in terms of past social experiences and to reaffirm the impression that life has a course and the self has a purpose. All participants found that accessing treatment from the Rhodes University Health Care Centre positively influenced their experiences of adherence and reconstruction of narratives. The study indicates that HIV-related interventions in place at the university need to pay more attention to the psychosocial needs of PLWH, involvement of PWLH, as well as keeping up with the continuously changing global HIV narrative. The study argues for more attention to in-depth experiences and personal narratives in HIV and AIDS, and PLWHA education at Rhodes University. , Thesis (PhD) -- Humanities, Department of Sociology, 2021
- Full Text:
- Date Issued: 2021-04
Invasion status and impact potential of Florida bass Micropterus floridanus in South Africa
- Authors: Khosa, Dumisani
- Date: 2020
- Subjects: Micropterus floridanus , Florida largemouth bass -- South Africa , Black bass -- South Africa , Micropterus floridanus -- South Africa -- Habitat , Florida largemouth bass -- South Africa -- Habitat , Black bass -- South Africa -- Habitat , Introduced fishes -- Environmental aspects -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165733 , vital:41276
- Description: In South Africa, the introduction of alien fishes was largely driven by the development of recreational fishing opportunities. Government-backed programmes resulted in the introduction of four Black Bass species: Micropterus salmoides, Micropterus dolomieu, Micropterus punctulatus and Micropterus floridanus. These species are regarded as the primary threat to native biota and there is an urgent need to assess their spread and impacts. This thesis focuses on: assessing the current distribution of all four Black Basses; using genetic techniques to establish the extent of hybridisation between M. salmoides and M. floridanus, and using functional responses to assess the impact potential of M. salmoides and M. floridanus under the context dependence of temperatures and habitat complexity. Maximum entropy modelling of habitat suitability for Black Bass highlighted that M. salmoides had broad climatic suitability across South Africa, while suitability for M. dolomieu and M. punctulatus was restricted to the Cape Fold Ecoregion. An extensive area-based invasion debt was observed for all Micropterus spp. To better understand the dynamics of hybridisation between M. salmoides and M. floridanus, 38 species-diagnostic single nucleotide polymorphism was used to screen Black Bass populations from the Breede River and Kowie River catchments. Micropterus salmoides alleles were more prevalent than M. floridanus in both the Breede River catchments (69.1% and 30.9%, respectively) and Kowie River catchments (63.3% and 36.7%, respectively). However, isolated populations found in dams (reservoirs) remained free from hybridisation. To compare resource utilisation (i.e. per capita effects) between M. salmoides and M. floridanus, two experimental chapters were designed. Chapter 4 focuses on how temperature mitigates per capita effects between the two Black Basses. There was a significant decrease in per capita effects for M. salmoides with increasing temperatures, while the converse was true for M. floridanus. Chapter 5 gives an account of the influence of habitat complexity on per capita effects. The results showed that habitat complexity did mitigate per capita effects, specifically on M. floridanus, which showed a significant drop in per capita effects; however, no significant difference was recorded for M. salmoides. In the two experimental chapters, M. floridanus exhibited a superior per capita effect compared to M. salmoides, implying higher predation impact on native biota.
- Full Text:
- Date Issued: 2020
- Authors: Khosa, Dumisani
- Date: 2020
- Subjects: Micropterus floridanus , Florida largemouth bass -- South Africa , Black bass -- South Africa , Micropterus floridanus -- South Africa -- Habitat , Florida largemouth bass -- South Africa -- Habitat , Black bass -- South Africa -- Habitat , Introduced fishes -- Environmental aspects -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165733 , vital:41276
- Description: In South Africa, the introduction of alien fishes was largely driven by the development of recreational fishing opportunities. Government-backed programmes resulted in the introduction of four Black Bass species: Micropterus salmoides, Micropterus dolomieu, Micropterus punctulatus and Micropterus floridanus. These species are regarded as the primary threat to native biota and there is an urgent need to assess their spread and impacts. This thesis focuses on: assessing the current distribution of all four Black Basses; using genetic techniques to establish the extent of hybridisation between M. salmoides and M. floridanus, and using functional responses to assess the impact potential of M. salmoides and M. floridanus under the context dependence of temperatures and habitat complexity. Maximum entropy modelling of habitat suitability for Black Bass highlighted that M. salmoides had broad climatic suitability across South Africa, while suitability for M. dolomieu and M. punctulatus was restricted to the Cape Fold Ecoregion. An extensive area-based invasion debt was observed for all Micropterus spp. To better understand the dynamics of hybridisation between M. salmoides and M. floridanus, 38 species-diagnostic single nucleotide polymorphism was used to screen Black Bass populations from the Breede River and Kowie River catchments. Micropterus salmoides alleles were more prevalent than M. floridanus in both the Breede River catchments (69.1% and 30.9%, respectively) and Kowie River catchments (63.3% and 36.7%, respectively). However, isolated populations found in dams (reservoirs) remained free from hybridisation. To compare resource utilisation (i.e. per capita effects) between M. salmoides and M. floridanus, two experimental chapters were designed. Chapter 4 focuses on how temperature mitigates per capita effects between the two Black Basses. There was a significant decrease in per capita effects for M. salmoides with increasing temperatures, while the converse was true for M. floridanus. Chapter 5 gives an account of the influence of habitat complexity on per capita effects. The results showed that habitat complexity did mitigate per capita effects, specifically on M. floridanus, which showed a significant drop in per capita effects; however, no significant difference was recorded for M. salmoides. In the two experimental chapters, M. floridanus exhibited a superior per capita effect compared to M. salmoides, implying higher predation impact on native biota.
- Full Text:
- Date Issued: 2020
Developing macroinvertebrate trait- and taxonomically-based approaches for biomonitoring wadeable riverine systems in the Niger delta, Nigeria
- Authors: Edegbene, Ovie Augustine
- Date: 2020
- Subjects: Water – Pollution -- Nigeria -- Niger River Delta , Stream health -- Nigeria -- Niger River Delta , Water -- Pollution -- Measurement , Environmental monitoring -- Nigeria -- Niger River Delta , Water quality -- Nigeria -- Niger River Delta , Water quality biological assessment -- Nigeria -- Niger River Delta , Aquatic invertebrates -- Nigeria -- Niger River Delta , Stream restoration -- Nigeria -- Niger River Delta , Urban agriculture -- Nigeria -- Niger River Delta , Stream ecology -- Nigeria -- Niger River Delta
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140660 , vital:37907
- Description: Riverine systems are increasingly subjected to pollution due to rapid urbanisation, industrialisation, and agricultural activities. Increasing pollution in freshwater systems impairs water quality, causes biodiversity loss and impairs aquatic ecosystem functionality and supply of ecosystem services. Rivers in the Niger Delta region of Nigeria are particularly vulnerable to urban pollution and agricultural activities as natural forests are increasingly replaced by urbanisation and agriculture. The differential effects of these pressures on the ecological processes of these river systems are poorly explored, as is the development of appropriate biomonitoring tools for routine monitoring of river health. In this study, a physico-chemically-based approach and macroinvertebrate trait- and taxonomic- approaches were developed to better understand the effects of multiple pressures on riverine systems, while developing multimetric indices to enable sustainable management of rivers within the region. Sixty-six stations in 20 river systems within the Edo and Delta States of the Niger Delta ecoregion were monitored seasonally for a period of five (2008–2012) years. The physico-chemically based approach makes apparent the extent of degradation of rivers and streams in the Niger Delta. For each dominant land use type, river stations were classified into least impacted stations (LIS), moderately impacted stations (MIS) or heavily impacted stations (HIS). Of 11 stations within urban catchments, only two were considered least impacted, suggesting that urgent measures are necessary to revise the current trajectories of urban rivers within the region. Most of the stations designated as MIS and HIS in the urban and urban-agriculture catchments were found to be significantly correlated with increased nutrients, EC and BOD5. Characteristics of most of the MIS and HIS within rivers in urban catchments evidenced the so-called urban stream syndrome, a state of persistent degradation of urban streams. The results of the traits and ecological preferences approach showed traits sensitive to urban and urban-agriculture pollution. Traits and ecological preferences that were associated with the LIS include the possession of hardshell, moderate and high sensitivities to oxygen depletion, very large body sized individuals (>20-40mm), swimmers, flattened body shape, a preference for temporary attachment, crawling, respiration with aerial/vegetation, possession of breathing tubes, possession of strap or other apparatus for respiration, streamlined body, and a high sensitivity to oxygen depletion. Permanent attachment as an ecological preference associated with LIS was also positively correlated with increasing dissolved oxygen (DO) and was deemed a pollution sensitive ecological preference. The possession of very small body size (<5mm), associated with HIS, was deemed a pollution-tolerant trait and was negatively correlated with DO, confirming the deteriorating state of the urban and urban-agricultural rivers. The impact of urban-forestry pollution on the distribution pattern of macroinvertebrate traits and ecological preferences was also explored in the selected rivers. Traits and ecological preferences such as possession of hard-shell, large body size, and grazing as a feeding preference which were significantly positively associated with the LIS, were also either significantly positively correlated with DO, or significantly negatively correlated with increasing any two of flow velocity, water temperature, BOD5 and nutrient. These traits and ecological preferences were deemed sensitive in forested rivers receiving urban pollution. Further, burrowing, the pupa aquatic stage, and predation which were significantly positively associated with HIS on the RLQ ordination, were also significantly negatively associated with DO. These traits were deemed tolerant of forested systems receiving urban pollution. Multimetric indices (MMI) were developed, validated and applied for urban, urban-agriculture and urban-forested (MMI-urban, MMI-urban-agric and urban-forest) areas. Of the 26 metrics that satisfactorily discriminated between the LIS, the MIS, and the HIS for MMI-urban, only five metric were retained for integration into MMI-urban, they are log VeL, Hemiptera abundance, % Coleoptera + Hemiptera, % Chironomidae + Oligochaeta and Evenness index. Further, of the 18 metrics that satisfactorily discriminated between the LIS, the MIS, and the HIS for MMI-urban-agric, only 12 metrics were retained and nine proved to be redundant. The nine metrics represent different measures; two of them were retained in addition to Chironomidae/Diptera abundance, % Odonata and Oligochaeta richness. The two metrics selected in addition to the hironomidae/Diptera abundance, % Odonata and Oligochaeta richness were the Margalef index and the logarithm of relative abundance of sprawler. For the MMI-urban-forest, 14 metrics satisfactorily discriminated between the LIS, the MIS, and the HIS, and 12 metrics were retained and 11 proved to be redundant. The non-redundant metric was Trichoptera abundance. Three metrics were further selected in addition to the Trichoptera abundance which include % Chironomidae + Oligochaeta, Coleoptera + Hemiptera richness and Shannon diversity. The MMI-urban and MMI-urban-agric indices performed better for LIS designated stations compared to the MIS and HIS deignated stations. The developed indices proved effective as biomonitoring tools for assessing the ecological health of rivers in the urban and urban-agriculture catchments within the Niger Delta. Overall, the results of the macroinvertebrate traits and ecological preferences, and taxonomic approaches showed the strength in the complementarity of both approaches in developing biomonitoring tools for assessing levels of deterioration in riverine systems. The study contributes significantly to understanding the ecology of riverine systems in the Niger Delta, particularly those subject to urban stresses, agricultural activities and urban pollution in forested systems, and thus makes an important contribution to the science and practice of biomonitoring in Nigeria where such studies are sparse.
- Full Text:
- Date Issued: 2020
- Authors: Edegbene, Ovie Augustine
- Date: 2020
- Subjects: Water – Pollution -- Nigeria -- Niger River Delta , Stream health -- Nigeria -- Niger River Delta , Water -- Pollution -- Measurement , Environmental monitoring -- Nigeria -- Niger River Delta , Water quality -- Nigeria -- Niger River Delta , Water quality biological assessment -- Nigeria -- Niger River Delta , Aquatic invertebrates -- Nigeria -- Niger River Delta , Stream restoration -- Nigeria -- Niger River Delta , Urban agriculture -- Nigeria -- Niger River Delta , Stream ecology -- Nigeria -- Niger River Delta
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140660 , vital:37907
- Description: Riverine systems are increasingly subjected to pollution due to rapid urbanisation, industrialisation, and agricultural activities. Increasing pollution in freshwater systems impairs water quality, causes biodiversity loss and impairs aquatic ecosystem functionality and supply of ecosystem services. Rivers in the Niger Delta region of Nigeria are particularly vulnerable to urban pollution and agricultural activities as natural forests are increasingly replaced by urbanisation and agriculture. The differential effects of these pressures on the ecological processes of these river systems are poorly explored, as is the development of appropriate biomonitoring tools for routine monitoring of river health. In this study, a physico-chemically-based approach and macroinvertebrate trait- and taxonomic- approaches were developed to better understand the effects of multiple pressures on riverine systems, while developing multimetric indices to enable sustainable management of rivers within the region. Sixty-six stations in 20 river systems within the Edo and Delta States of the Niger Delta ecoregion were monitored seasonally for a period of five (2008–2012) years. The physico-chemically based approach makes apparent the extent of degradation of rivers and streams in the Niger Delta. For each dominant land use type, river stations were classified into least impacted stations (LIS), moderately impacted stations (MIS) or heavily impacted stations (HIS). Of 11 stations within urban catchments, only two were considered least impacted, suggesting that urgent measures are necessary to revise the current trajectories of urban rivers within the region. Most of the stations designated as MIS and HIS in the urban and urban-agriculture catchments were found to be significantly correlated with increased nutrients, EC and BOD5. Characteristics of most of the MIS and HIS within rivers in urban catchments evidenced the so-called urban stream syndrome, a state of persistent degradation of urban streams. The results of the traits and ecological preferences approach showed traits sensitive to urban and urban-agriculture pollution. Traits and ecological preferences that were associated with the LIS include the possession of hardshell, moderate and high sensitivities to oxygen depletion, very large body sized individuals (>20-40mm), swimmers, flattened body shape, a preference for temporary attachment, crawling, respiration with aerial/vegetation, possession of breathing tubes, possession of strap or other apparatus for respiration, streamlined body, and a high sensitivity to oxygen depletion. Permanent attachment as an ecological preference associated with LIS was also positively correlated with increasing dissolved oxygen (DO) and was deemed a pollution sensitive ecological preference. The possession of very small body size (<5mm), associated with HIS, was deemed a pollution-tolerant trait and was negatively correlated with DO, confirming the deteriorating state of the urban and urban-agricultural rivers. The impact of urban-forestry pollution on the distribution pattern of macroinvertebrate traits and ecological preferences was also explored in the selected rivers. Traits and ecological preferences such as possession of hard-shell, large body size, and grazing as a feeding preference which were significantly positively associated with the LIS, were also either significantly positively correlated with DO, or significantly negatively correlated with increasing any two of flow velocity, water temperature, BOD5 and nutrient. These traits and ecological preferences were deemed sensitive in forested rivers receiving urban pollution. Further, burrowing, the pupa aquatic stage, and predation which were significantly positively associated with HIS on the RLQ ordination, were also significantly negatively associated with DO. These traits were deemed tolerant of forested systems receiving urban pollution. Multimetric indices (MMI) were developed, validated and applied for urban, urban-agriculture and urban-forested (MMI-urban, MMI-urban-agric and urban-forest) areas. Of the 26 metrics that satisfactorily discriminated between the LIS, the MIS, and the HIS for MMI-urban, only five metric were retained for integration into MMI-urban, they are log VeL, Hemiptera abundance, % Coleoptera + Hemiptera, % Chironomidae + Oligochaeta and Evenness index. Further, of the 18 metrics that satisfactorily discriminated between the LIS, the MIS, and the HIS for MMI-urban-agric, only 12 metrics were retained and nine proved to be redundant. The nine metrics represent different measures; two of them were retained in addition to Chironomidae/Diptera abundance, % Odonata and Oligochaeta richness. The two metrics selected in addition to the hironomidae/Diptera abundance, % Odonata and Oligochaeta richness were the Margalef index and the logarithm of relative abundance of sprawler. For the MMI-urban-forest, 14 metrics satisfactorily discriminated between the LIS, the MIS, and the HIS, and 12 metrics were retained and 11 proved to be redundant. The non-redundant metric was Trichoptera abundance. Three metrics were further selected in addition to the Trichoptera abundance which include % Chironomidae + Oligochaeta, Coleoptera + Hemiptera richness and Shannon diversity. The MMI-urban and MMI-urban-agric indices performed better for LIS designated stations compared to the MIS and HIS deignated stations. The developed indices proved effective as biomonitoring tools for assessing the ecological health of rivers in the urban and urban-agriculture catchments within the Niger Delta. Overall, the results of the macroinvertebrate traits and ecological preferences, and taxonomic approaches showed the strength in the complementarity of both approaches in developing biomonitoring tools for assessing levels of deterioration in riverine systems. The study contributes significantly to understanding the ecology of riverine systems in the Niger Delta, particularly those subject to urban stresses, agricultural activities and urban pollution in forested systems, and thus makes an important contribution to the science and practice of biomonitoring in Nigeria where such studies are sparse.
- Full Text:
- Date Issued: 2020
An integrative approach to understanding vulnerability of an alpine range-restricted bird to climate warming
- Authors: Oswald, Krista Natasha
- Date: 2020
- Subjects: Passeriformes -- South Africa -- Western Cape , Passeriformes -- Physiology -- South Africa -- Western Cape , Passeriformes -- Behavior -- Climatic factors -- South Africa -- Western Cape , Passeriformes -- Reproduction -- Climatic factors -- South Africa -- Western Cape , Passeriformes -- Dispersal -- South Africa -- Western Cape , Passeriformes -- Food -- South Africa -- Western Cape , Passeriformes -- Nests-- South Africa -- Western Cape , Blue Hill Nature Reserve , Cape Rockjumper -- Climatic factors , Chaetops frenatus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148517 , vital:38746
- Description: Understanding species' vulnerability to climate change requires an integrative ecological approach involving, at minimum, physiology, behaviour, reproductive success, and limitations on dispersal. In this thesis I determined potential negative effects of increasing temperatures on behaviour, reproduction, and ability to disperse in an alpine-restricted bird, the Cape Rockjumper Chaetops frenatus ("Rockjumper"). Here I provide a comprehensive ecological set of data for understanding the link between Rockjumper population declines and warming habitats. I tested whether Rockjumper microsite-use at high temperatures resulted in decreased time spent on important behaviours, such as foraging. I found Rockjumpers made increased use of rock-shade as air temperature increased and so spent less time panting, but birds in rock-shade foraged less. Birds may be constrained to foraging in sun at high temperatures to sustain energy or water requirements, despite risks of high thermal load, or else face lost foraging opportunities by remaining in rock-shade. I determined if adult nest attendance and causes of nest failure were related to high temperatures. I filmed nests over two breeding seasons to examine temperature-effects on adult time in nests, provisioning rate, and resultant nestling daily mass gain. The only temperature effect I found was decreased percent daily change in body mass for older nestlings at hotter temperatures. I also examined causes of nest failure over three breeding seasons in relation to nest concealment and habitat openness by observing failure/success. Nests in more open territories (i.e. early post-fire habitat) had greater success, and the main cause of predation came from Boomslang Dispholydus typus. Importantly, the probability of Boomslang predation increased significantly at hotter temperatures. These findings show there may be direct negative effects of increasing temperatures on reproductive success and population recruitment, and so hotter temperature during the breeding season may be at least partly responsible for observed population declines. Lastly, I examined genetic structure of populations across mountain ranges separated from one another by lowland habitat unsuitable for Rockjumpers. I predicted I would find little evidence for dispersal between mountain ranges separated by unsuitable lowland habitat, but instead found Rockjumpers show little evidence for inbreeding. I also found evidence for a past bottleneck event or founder effect, and little overall genetic diversity (possibly as their specialized niche exerts selective pressure). Low diversity may limit Rockjumpers' ability to adapt to a changing environment. Adult physiological and behavioural thresholds to increasing temperatures are often used to create predictions of climate change effects. My past physiological research and current behavioural research suggest no particularly strong evidence that temperature-related population declines are driven by poor physiological capacity to tolerate heat or negative behaviour trade-offs. Instead, my current research shows that understanding negative effects of increasing temperatures may require a more in-depth approach involving investigation of fine-scale ecological interactions. No single one of my chapters provides the insight necessary for understanding Rockjumper population declines at warming temperatures. Instead, I show how an integrative approach may be necessary for assessing species' vulnerability to climate change by examining multiple ecological aspects of a single sentinel species, using an alpine species with a narrow thermal range and highly specialized habitat niche.
- Full Text:
- Date Issued: 2020
- Authors: Oswald, Krista Natasha
- Date: 2020
- Subjects: Passeriformes -- South Africa -- Western Cape , Passeriformes -- Physiology -- South Africa -- Western Cape , Passeriformes -- Behavior -- Climatic factors -- South Africa -- Western Cape , Passeriformes -- Reproduction -- Climatic factors -- South Africa -- Western Cape , Passeriformes -- Dispersal -- South Africa -- Western Cape , Passeriformes -- Food -- South Africa -- Western Cape , Passeriformes -- Nests-- South Africa -- Western Cape , Blue Hill Nature Reserve , Cape Rockjumper -- Climatic factors , Chaetops frenatus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148517 , vital:38746
- Description: Understanding species' vulnerability to climate change requires an integrative ecological approach involving, at minimum, physiology, behaviour, reproductive success, and limitations on dispersal. In this thesis I determined potential negative effects of increasing temperatures on behaviour, reproduction, and ability to disperse in an alpine-restricted bird, the Cape Rockjumper Chaetops frenatus ("Rockjumper"). Here I provide a comprehensive ecological set of data for understanding the link between Rockjumper population declines and warming habitats. I tested whether Rockjumper microsite-use at high temperatures resulted in decreased time spent on important behaviours, such as foraging. I found Rockjumpers made increased use of rock-shade as air temperature increased and so spent less time panting, but birds in rock-shade foraged less. Birds may be constrained to foraging in sun at high temperatures to sustain energy or water requirements, despite risks of high thermal load, or else face lost foraging opportunities by remaining in rock-shade. I determined if adult nest attendance and causes of nest failure were related to high temperatures. I filmed nests over two breeding seasons to examine temperature-effects on adult time in nests, provisioning rate, and resultant nestling daily mass gain. The only temperature effect I found was decreased percent daily change in body mass for older nestlings at hotter temperatures. I also examined causes of nest failure over three breeding seasons in relation to nest concealment and habitat openness by observing failure/success. Nests in more open territories (i.e. early post-fire habitat) had greater success, and the main cause of predation came from Boomslang Dispholydus typus. Importantly, the probability of Boomslang predation increased significantly at hotter temperatures. These findings show there may be direct negative effects of increasing temperatures on reproductive success and population recruitment, and so hotter temperature during the breeding season may be at least partly responsible for observed population declines. Lastly, I examined genetic structure of populations across mountain ranges separated from one another by lowland habitat unsuitable for Rockjumpers. I predicted I would find little evidence for dispersal between mountain ranges separated by unsuitable lowland habitat, but instead found Rockjumpers show little evidence for inbreeding. I also found evidence for a past bottleneck event or founder effect, and little overall genetic diversity (possibly as their specialized niche exerts selective pressure). Low diversity may limit Rockjumpers' ability to adapt to a changing environment. Adult physiological and behavioural thresholds to increasing temperatures are often used to create predictions of climate change effects. My past physiological research and current behavioural research suggest no particularly strong evidence that temperature-related population declines are driven by poor physiological capacity to tolerate heat or negative behaviour trade-offs. Instead, my current research shows that understanding negative effects of increasing temperatures may require a more in-depth approach involving investigation of fine-scale ecological interactions. No single one of my chapters provides the insight necessary for understanding Rockjumper population declines at warming temperatures. Instead, I show how an integrative approach may be necessary for assessing species' vulnerability to climate change by examining multiple ecological aspects of a single sentinel species, using an alpine species with a narrow thermal range and highly specialized habitat niche.
- Full Text:
- Date Issued: 2020