List of Titles

Biological longitudinal aspects of the Kabompo River, a significant tributary of the upper Zambezi sub-catchment, North-west Province, Zambia

- Janse van Rensburg, Lomarie Cathleen

Authors: Janse van Rensburg, Lomarie Cathleen
Date: 2023-03-29
Subjects: Nutrient cycles , Stable isotopes , Redeye Labeo , Synodontis , Zambezi River Watershed Ecology , Aquatic ecology
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/422292 , vital:71928
Description: The landscape of the Upper Zambezi Catchment in the remote North-Western Province of Zambia retains many natural features, but current and future anthropogenic activities threaten its integrity. Lack of information relating to the basic ecological functioning of the region hampers conservation efforts. Flooding from the adjacent woody-savanna and open grasslands in the Upper-Zambezi Catchment in the wet season drives crucial processes in the aquatic ecosystems such as the Kabompo River. This thesis describes aquatic food webs and describes the nutrient cycling in this river. A general introduction was based on the seasonality, river morphology, and biodiversity of the Kabompo River. There is no aquatic food web information available on this river. To address this knowledge gap, sampling of the principal food web components– vegetation, invertebrates, and fish – were collected in the dry season from August to September 2019 across six sites in the Kabompo River. Stable isotope analyses provided proxies for the food web structure at each site, and were the basis of longitudinal comparisons. The analyses suggest that the Kabompo River food webs follow the trophic ordination and nutrient cycling characteristic of the revised-Riverine Productivity Model. Food webs and community assemblages remain structurally similar between sites and provide some evidence of bottom-up productivity-driven trophic dynamics. To predict the possible landscape-scale processing of nutrient changes present for the aquatic ecosystems of the Kabompo River, a longitudinal comparison between a herbivore, Labeo cylindricus, and omnivore, Synodontis spp., fish species and their resources (primary producers and invertebrates) was done and showed archetypal fish food web trophic separation (2 ‰ to3 ‰) between species which remains consistent for the headwater sites. The nutrient values change at the convergence between the Kabompo Bridge and the Mwinilunga branches and show a decrease in the trophic separation of the sites below. This change becomes apparent from the last site, Watopa, where the trophic separation re-establishes (2 ‰ to 3 ‰) between the species. The trend suggests primarily autochthonous production in the headwater reaches, changing to allochthonous and autochthonous nutrient incorporation after the convergence of the two main branches. Permanent wetlands surrounding the convergence zones may be conducive to more primary producer activity and increased nutrient turnover. Permanent wetlands are a common feature of the Upper Zambezi Catchment tributaries, with the most notable lentic system the Barotse Flood Plains in the south, which shares reach-adjacent characteristics with the Kabompo River. Trends from the 2015 dry season identified for the Barotse Flood Plains support the findings of this thesis, where the δ13C values recorded reach depletion of -45 ‰. Management in the Upper Zambezi Basin and the Kabompo River comprises biannual assessments of water quality and quantity by the Zambezi River Authority, but not of the ecosystem process. This thesis may provide information to address the ecological (food webs and nutrient cycling) dynamics of the Basin rivers. As the first baseline information on the river's biology and ecology, it may present a comparative basis for future assessments under conservation management strategies. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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Date Issued: 2023-03-29

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Effect of Helicosporidium sp. (Chlorophyta; Trebouxiophyceae) infection on Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), a biological control agent for the invasive Salvinia molesta D.S. Mitchell (Salviniaceae) in South

- Mphephu, Tshililo Emmanuel

Authors: Mphephu, Tshililo Emmanuel
Date: 2022-10-14
Subjects: Salvinia molesta South Africa , Weeds Biological control , Cyrtobagous salviniae , Ketoconazole
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/365815 , vital:65792 , DOI https://doi.org/10.21504/10962/365815
Description: The effectiveness of established biological control agents depends on biotic and abiotic interactions in the introduced range. The weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), was released as a biological control against Salvinia molesta D.S. Mitchell (Salviniaceae) in South Africa in 1985. This agent has been highly successful against S. molesta and has significantly reduced the weed’s populations around the country. However, in 2007, the parasitic alga, Helicosporidium sp. (an undescribed species), was detected in field-collected C. salviniae adults in South Africa. The distribution and impacts of this disease on the weevil and its efficacy as a control agent were not known. In this thesis, the prevalence, infection load, and impact of Helicosporidium sp. on C. salviniae was determined. In 2019, adult weevils were collected from 10 sites across the Eastern Cape, KwaZulu-Natal, Limpopo, and Western Cape provinces and screened to determine the occurrence, infection load, and geographic distribution of Helicosporidium sp. Transmission mechanisms of this disease in C. salviniae were then evaluated. The possible impact of Helicosporidium sp. was assessed by comparing the feeding rates and the reproductive output of the diseased and healthy adults of C. salviniae. An attempt was then made to eliminate the disease in C. salviniae through the application of the antibiotic, ketoconazole. Further, the role of temperature on infection load in C. salviniae was also assessed. Finally, recommendations for the long-term biological control programme against S. molesta in South Africa were made. The disease covers the entire distribution range of C. salviniae in South Africa, with the disease occurrence rate ranging from 92.15% to 100% insects infected per site. Helicosporidium sp. was found to transmit vertically within the populations of C. salviniae. Infection by the Helicosporidium sp. disease reduced the reproductive output of C. salviniae as well its impact on biomass reduction of S. molesta when a diseased culture was compared to a healthy culture from the USA. 98.44 to 98.55% of Helicosporidium sp. loads were reduced through multiple applications of ketoconazole concentrations under in vitro trials. In vivo treatments resulted in 70% control of Helicosporidium sp. in the adults of C. salviniae that were fed ketoconazole three times over a 21 day period. Adult C. salviniae feeding and survival performances were similar when fed fronds of S. molesta inoculated with ketoconazole and water. The lowest and highest disease loads of Helicosporidium sp. were recorded when the weevils were reared at 30°C and 14°C, respectively. As expected, the highest impact and reproductive output of C. salviniae were at 30°C. The evaluations discussed in this thesis highlight the role of diseases in biological control agents, and gaps in both the pre-release and post-release monitoring that should integrate screening of diseases in these studies. Although the combined application of the antibiotic and temperature will reduce Helicosporidium sp. loads and impact, this technology is most likely only applicable where the weevils are reared in small numbers in a rearing facility and not really applicable to the field situation. It is important to release healthy agents that will cause efficient control of the target weed plant species, therefore, when introducing new biological control agents, the health status of such agents needs to be understood. Therefore, long-term field monitoring and assessment of the impact of C. salviniae on S. molesta should be conducted to track all the changes that may result due to the presence of Helicosporidium sp. This long-term monitoring and assessment will give a more informative role of Helicosporidium sp. in field populations of C. salviniae. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
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Date Issued: 2022-10-14

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Exploring how Grade 9 Physical Science teachers mediate learning of the topic of chemical changes

- Likando, Orrice Munukayumbwa

Authors: Likando, Orrice Munukayumbwa
Date: 2021-04
Subjects: Science -- Study and teaching (Secondary) -- Namibia , Chemistry -- Study and teaching (Secondary) -- Namibia , Culturally relevant pedagogy , Pedagogical content knowledge , Prior learning -- Namibia
Language: English
Type: thesis , text , Masters , MEd
Identifier: http://hdl.handle.net/10962/177918 , vital:42890
Description: The examiners’ reports for 2013-2018 indicated that learners consistently perform poorly in questions based on chemical changes. My assumption is that the reason why learners are challenged with understanding the topic of chemical changes could be due to the way this topic is taught. It is against this background that this study explored how grade 9 Physical Science teachers mediated learning of the topic of chemical changes. The study is underpinned by an interpretive paradigm. Within the interpretive paradigm, a qualitative case study research design was employed. It was conducted at two different schools in the Otjozondjupa region with two Physical Science teachers. Data were collected using semi-structured interviews, lesson observations, stimulated recall interviews, and teachers’ reflections. The study is informed by Vygotsky’s socio-cultural theory together with Shulman’s pedagogical content knowledge as the theoretical frameworks. A thematic approach to data analysis was adopted. That is, qualitative data were analysed inductively to come up with sub-themes to form themes. Moreover, validation and trustworthiness were completed through data triangulation, member checking, and watching videotaped lessons with the participants. The findings of this study revealed that the topic of chemical changes has many examples which can be used during mediation. Teachers seemed to be aware of integrating learners’ experiences into their lessons. Furthermore, they were aware that they should improvise resources during mediation of learning. In contrast, during lesson observations, the findings revealed an imbalance between this awareness and the actual knowledge of using easily accessible materials, and the elicitation and integration of prior knowledge throughout the science lessons. Moreover, hands-on practical activities were lacking in the mediation process and instead, traditional methods of teaching tended to dominate. Nonetheless, teachers’ reflections influenced them to analyse and strengthen their lessons. Thus, the study recommends that there is a need for teachers to have mentorships and platforms which can expose them to the knowledge of different types of easily accessible materials. This might strengthen their PCK. Teachers are also encouraged to do some reflections after very lesson as these have a potential to influence their pedagogical practices. , Thesis (MEd) -- Faculty of Education, Education, 2021
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Date Issued: 2021-04

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Health factors associated with traditional circumcision of adolescent males in Alice, Raymond Mhlaba local municipality, Eastern Cape

- Mpateni, Aphiwe https://orcid.org/0000-0002-6823-9179

Authors: Mpateni, Aphiwe https://orcid.org/0000-0002-6823-9179
Date: 2016-06
Subjects: Circumcision , Penis -- Surgery http://id.loc.gov/authorities/subjects/sh85099485
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10353/19726 , vital:43183
Description: This research explored the health challenges associated with male adolescents during traditional male circumcision in Alice,Raymond Mhlaba Local Municipality in Eastern Cape. This researcher used the views, attitudes and perceptions of the male adolescents who recently underwent traditional male circumcision, the parents of the male adolescents, health practitioners, community leaders, traditional nurses, traditional surgeons and a member of Association of Ingcibi Namakhankatha. The research study aimed at achieving the following specific objectives: 1. to interrogate the attitudes and views of people on the health factors associated with male adolescents who undergo traditional male circumcision 2; to establish the psychological, social, emotional and behavioural impacts of health challenges experienced by male adolescents undergoing male traditional circumcision; and 3. to document the health hazards experienced by male adolescents undergoing during traditional male circumcision. This researcher espoused a qualitative research method. The study was conducted through qualitative research instruments such as in-depth interviews, focus groups interviews and key informants in collecting the data. The study utilized socio cultural theory. The smaple in this study was made up of 25 participants: five (5) traditionally circumcised youth, ten (10) health practitioners, five (5) parents, one (1) traditional surgeon, two (2) traditional nurses, one (1) community leader and one (1) member of Association of Ingcibi Namakhankatha. Non probability sampling methodology was used, specifically purposive sampling to select the participants because of their knowledge and experiences about traditional male circumcision. Data was analysed thematically. The study came with the following findings: An array of health hazard experienced associated with circumcision rite; Horror emanating from the deaths of the initiates; Possible contraction and transmission of diseases during the rite; Cultural custodians disregarding health ethos and sanitation; Traditional male circumcision becoming a forum of learning immoral behaviours; Tightening of the bandages was believed to expedite healing; Amputation of penis due to complications; Psychological and emotional state of the initiates who suffer clinical hazards; Incompetence of traditional surgeons and untrained traditional nurses compromising the health of the initiates; Parental ignorance leading to their sons falling victims of the clinical health hazards; and subjugation of women in cultural practices. The research study made the following recommendations: strengthening the monitoring and evaluation of traditional practitioners; Community engagements by training boys to prepare for traditional male circumcision; Emphasizing the role of culture as stated by section 31 of the South African constitution; bolstering the selection criteria of traditional nurses.The traditional male circumcision practice to enlist the role of women as important stakeholders because they are the mothers; and imposing strict penalties against cultural custodians operating illegal schools This researcher, therefore, hopes that all the health hazards associated with male adolescents during traditional male circumcision can be addressed and that the government and the communities need to engage one another inorder to come with ways and strategies of managing cultures. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2016
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Date Issued: 2016-06

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