Electronic Theses and Dissertations (Masters)
Permanent URI for this collectionhttps://hdl.handle.net/10539/37999
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Item The Effects of Land Use Change on Water Quality in the upper Berg - and Breede River catchments, Western Cape, South Africa(University of the Witwatersrand, Johannesburg, 2024-08) van Wyngaard, Zahn; Sheridan, CraigPollution of surface water resources is gaining global attention due to increasing freshwater stress and scarcity. This study assessed how land use changes in the upper catchments of the Berg and Breede rivers affect water quality. Land Cover Data, covering a 22-year period, was prepared, categorised, and analysed. Land use classes include “natural”, “urban”, “agricultural”, “water bodies”, “mining” as well as “degraded land, bare rock, and soil”. Changes of these land use classes were analysed to establish their influence on water quality parameters such as electrical conductivity, pH, total nitrogen including ammonium, nitrate and nitrite, orthophosphate, and sulfate. In the Berg River catchment, urban, natural, water bodies and degraded land, bare rock, and soil increased while agricultural and mining decreased. In the Breede River catchment, urban, water bodies and degraded land, bare rock, and soil as well as mining increased while agricultural and natural decreased. In the Berg River catchment, Dissolved Inorganic Nitrogen (ammonium, nitrate and nitrite), as well as pH increased while electrical conductivity, sulfate, and orthophosphate decreased. In the Breede River catchment, ammonium and orthophosphate increased while a decrease in electrical conductivity, nitrate and nitrite, pH, and sulfate was noted. In the Berg River catchment, the following correlations, or relationships, were noted. Urban land was correlated with ammonium and sulfate; agricultural land was correlated with electrical conductivity and sulfate, natural land cover was correlated with electrical conductivity, orthophosphate, and sulfate. Water bodies were correlated with orthophosphate, sulfate, degraded land, bare rock, and soil was correlated with ammonium and mining was correlated with electrical conductivity, orthophosphate, and sulfate. In the Breede River catchment, urban land was correlated with ammonium and orthophosphate, agricultural land was correlated with nitrate and nitrite and pH, and natural land cover was correlated with electrical conductivity, ammonium, and sulfate. Water bodies were correlated with electrical conductivity, nitrate and nitrite, and sulfate, degraded land, bare rock, and soil were correlated with electrical conductivity, ammonium, orthophosphate, and sulfate, and mining was correlated with electrical conductivity, ammonium and sulfate. The study therefore recommends that we mitigate land use change impacts on water quality by enforcing strict land-use regulations, promote sustainable agricultural practices, protect riparian areas and wetlands, implement better stormwater and wastewater management, educate the public, and coordinate integrated water resource management efforts to reduce pollution of scarce surface water resources.Item Assessing the climatic suitability and environmental responses of Anthonomus morticinus Clark (Coleoptera: Curculionidae), a potential biological control agent of Solanum mauritianum Scopoli (Solanaceae) in South Africa(University of the Witwatersrand, Johannesburg, 2024-10) Keizan, Yaron Yakov; Byrne, Marcus; Venter, NicInsect biology is greatly influenced by the surrounding climate. Desiccation, owing to low relative humidity, poses a significant threat to insect populations, especially those with small body sizes. To avoid exposure to low relative humidity (RH) levels, insects actively seek out nearby microenvironments with raised RH. The flowerbud feeding weevil Anthonomus morticinus is an optimistic agent to limit the spread of the highly invasive Solanum mauritianum throughout South Africa. However, the restricted geographic range shown by A. santacruzi in South Africa due to climatic unsuitability questions how A. morticinus will respond to climatic variables, particularly humidity. The effect of low temperatures has shown to be a limiting factor by Mkhomazi (2022) on the survival of A. morticinus, but the effects of RH remains untested. This study examined the influence of RH on the survival and oviposition of A. morticinus inhabiting S. mauritianum inflorescences. Furthermore, this study also intended to reveal the influence of lethal humidities on A. santacruzi cultures compared to that of A. morticinus when sheltered by host inflorescences. Anthonomus morticinus colonies inhabiting S. mauritianum bouquets were kept at seven relative humidities, from ~80% to ~20% for a period of 14 days. Survival and oviposition, observed by dissection of buds, were recorded. For comparison, colonies of A. morticinus and A. santacruzi were maintained at 20% and 46% relative humidity for seven days to determine if the species had differing responses at the lower RH levels. A. morticinus survival and oviposition showed no significant differences at the decreasing humidity levels. Moreover, no significant differences were observed in the survival between A. morticinus and A. santacruzi at 46% and 20% RH. Weevils residing within the S. mauritianum flowers and shoots were shielded from the unfavourable environmental humidities owing to higher humidity levels within these microclimates. These results highlight the dependence of biological control agents on their hosts for more than just food and reproduction but also for physiological functionality.Item Home range establishment of translocated African elephants (Loxodonta africana) in a savanna environment(University of the Witwatersrand, Johannesburg, 2023-09) Ngorima, Patmore; Parrini, Francesca; Boyers, Melinda; Mariotti, ElenaData from nine female African elephants translocated to Hurungwe Safari Area that had been collared was used to estimate home range patterns. Monthly home ranges for each elephant were estimated using the 50% and 95% Kernel Density Estimates (KDEs) method for a period of 20 months following translocation. At the population level, a linear regression model was used to test for the effect of months from release on the home range patterns. The findings revealed that the 95% home range of the elephants increased over time, while the 50% home range decreased since their initial release. I went further to compare the individual differences using the generalised additive model. The results showed some individual differences in patterns of exploration, with some displaying more linear home range patterns than others. Over and above, a considerably positive and relevant relationship between time and variation in the extent of the home range was observed.Item The function of “plant biltong” collected by bush Karoo rats (Otomys unisulcatus)(University of the Witwatersrand, Johannesburg, 2024) Sanweni Siyabong PatrickFood storing is a commonly observed strategy in many rodents living in environments with seasonally fluctuating food availability. Stored food allows small mammals to survive through food restricted periods and has been extensively studied in the northern hemisphere, characterised by cold winters. It could also be adaptive in semi-deserts of the southern hemisphere, such as the Succulent Karoo, which experience winter rainfall and hot dry summers. Here I want to understand the function of food plants carried back by bush Karoo rats (Otomys unisulcatus) to the stick lodges they build in the Succulent Karoo. Some of the food plants carried back to their lodges dry out, forming what I refer to as “plant biltong” or ‘plantong.’ To date, the function of the plantong remains unknown. Plantong might function as food in the dry season, or it might just be left over from food eaten at the lodge, or it can aid in construction of the lodges. I studied which plant species were collected as plantong, and whether there were seasonal differences in collection and consumption of plantong. I observed 15 lodges over 12 months and recorded the fate of plant pieces carried back to each lodge by bush Karoo rats. I tested experimentally whether they do eat the plantong. Plant species that were collected and dried out to become plantong were mostly annual shrubs (Zygophyllum retrofractum, Lycium cinereum, Salsola zeyheri, Helichrysum), grass species (Schismus) and perennials species (Atriplex, Drosanthemum spec, Galenia sarcophylla, Hermannia, Mesembryanthemum, oxalis sp, Chlorophytum crassinerve, Psilocaulon sp.). Most plant pieces were collected in winter and spring which is in the moist season. Plantong was consumed the most in the autumn (end of the dry season). Collected plant pieces were multifunctional. Most, 68%, of plant pieces carried back to the lodge were eaten green before they became plantong,Of the plant pieces that were collected, 12% were later eaten as plantong, 11% was incorporated into the structure of the lodge, while the fate of 9% was unknown. Experiments in captivity showed that bush Karoo rats indeed eat plantong. Plantong was not stored for months (from moist to dry season), but mostly days to weeks. Thus, I regard plantong as a food source derived from leftover food during collection and consumption but not as stored food for later consumption during harsh conditions.Item Characterisation of Drought Using Hydrological and Meteorological Indices: A Case Study of Bethlehem, South Africa(University of the Witwatersrand, Johannesburg, 2023) Tshabalala, Khanyisile; Evans, Mary; Masindi, KhulisoThe study aims to assess the severity and evolution of drought/s in Bethlehem using the hydrological: Streamflow Drought Index (SDI), Reconnaissance Drought Index (RDI), Effective Reconnaissance Drought Index (eRDI) and meteorological: Standardised Precipitation Index (SPI), Agricultural Standardised Precipitation Index (aSPI), and Precipitation Deciles (PD) indices. These indices were computed using the Drought Indices Calculator (DrinC). The RDI, eRDI, aSPI, and SPI identified three drought events between 1980 and 2017. The PD on the other hand, identified particular years between 1980 and 2017 that received below-normal to much below- normal precipitation. Further, the years identified to have received below normal to much below normal precipitation fell between the drought periods identified by the other indices, such as the 1980 – 1990 drought identified by the SPI, RDI, aSPI, and eRDI; the PD identified 1982, 198, 1985, and 1986 as specific years the received significantly low precipitation within the decade long drought. Of critical note is the absence of the SDI results, stream levels data was not available at the time the results presented in this report were computed. The unavailability of SDI values did not compromise or negatively affect the results presented in this study as the computed indices had a strong correlation, implying the reliability of the results presented in this reportItem The supply of ecosystem services along an urban-rural gradient, in Johannesburg, South Africa(University of the Witwatersrand, Johannesburg, 2024) Jaxa, Busisiwe; Schwaibold, U.Currently, the entire world is experiencing an unparalleled process of urbanisation, which is marked by an increase in population, economic progress, and the spread of urban areas. Although urbanisation presents opportunities such as economic advancement, enhanced infrastructure, and improved living conditions, it also brings about adverse effects on the natural environment. Ecosystem services vary along urban-rural gradients as they are largely affected by land use and land cover change. There is an increasing focus on urban ecosystem services that enhance urban resilience. Nonetheless, there has been minimal research conducted in South Africa regarding the effects of urbanisation on the provision of ecosystem services. This study aimed to investigate the impact of urbanisation on ecosystem services in the greater Johannesburg area and provide a deeper understanding of how the provision of three specific ecosystem services has evolved. These ecosystem services included temperature regulation, flood regulation and carbon sequestration. The land surface temperature (LST) along each gradient was derived from the Landsat (5 TM, 7 ETM+, 8 OLI) datasets available in the Google Earth Engine. Carbon storage was determined by estimating biomass using basic tree measurements. Soil compaction was measured as a proxy for the flood regulation ecosystem service. Lasty, land cover change was also assessed with the use of the ArcGIS software. The findings revealed that the supply of ecosystem services increased with an increasing distance from the city centre. Temperature and soil compaction were found to be high at the urban end of the gradient and carbon storage was found to be low at the urban end of the gradient. The land cover assessment revealed that the City of Johannesburg has suffered a substantial loss of green spaces over the 20 years, as the area covered by built-up surfaces increased. This study, therefore, has how how green spaces in urban areas enhance the sustainability of cities by supporting the supply of various ecosystem services including flood and climate regulation, carbon sequestration and storage. It has also shown that, the rapid urbanisation that the city experienced has led to a reduction in the overall supply of ecosystem services, whilst rural landscapes on the other hand continue to maintain the provision of these services. In order to enhance the green infrastructure in urban areas, it is recommended that, the urban natural systems are integrated in the urban planning and infrastructure initiativeItem Biodiversity stewardship in south africa - an assessment of the klipkraal biodiversity stewardship programme and its potential for conservation(University of the Witwatersrand, Johannesburg, 2024) Butler, KirstenThe importance of conservation in agriculture has become more apparent over the last couple of years, however it involves complex social-ecological relationships and as agriculture is a critical industry for human survival, biodiversity conservation in the industry is a major challenge worldwide. In South Africa, biodiversity stewardship programmes, which involve agreements between landowners and conservation authorities to secure land in biodiversity priority areas, are becoming a prominent method of conservation in agriculture. Yet there is a lack of research on the conservation benefits and whether they show improvements in the area’s biodiversity. This study focussed on the Klipkraal biodiversity stewardship programme which consists of two privately owned functional cattle farms in a peri-urban area of the southern grasslands of Gauteng making up 2 656 hectares of land of which 1 600 hectares are natural vegetation, and the remaining area is cultivated land used for farming maize and soya. The study sought to answer the question: what is the ecological state of the area and does this programme have potential for conservation in the long-term? The aim of this study was to assess the potential conservation benefits and sustainability of the Klipkraal biodiversity stewardship programme. The study involved both qualitative and quantitative data collection, including landcover mapping, field surveying to assess the vegetation state and mammal diversity and distribution of the site, and interviews with key stakeholders. The landcover mapping allowed for a visual representation of the various landcover types and percentage coverage of each of the six landcover types found in the study area. Vegetation assessments at five different sites resulted in an understanding of the vegetation structure, composition and cover across the two farms and from this it was established that the vegetation structure and species diversity differ, but the species composition is similar throughout the study site. An anthropogenic disturbance score was allocated to each site and the highest rated anthropogenic scores correlated with the sites consisting of the highest exotic species. The mammal assessments showed that the varying vegetation structure allows for specialist species to occupy a range of habitats within the site and also indicated that there are barriers to the movement of large mammals within the site. The results of the vegetation and mammal assessment which suggest a diverse range of vegetation units, habitats, and mammal diversity, emphasise that the area is important for conservation. The interviews revealed the multiple challenges involved in the Klipkraal Biodiversity Stewardship Programme and requirements in order for the programme to be successful in the long term. These include a need for willingness of landowners to put their time and resources into conservation efforts on their properties, a need for constant monitoring of management strategies, the importance of expanding the stewardship areas to ensure conservation of the entire area and not just isolated fragments of the area. However, key challenges in expanding the programme were also revealed, such as scepticism by landowners in entering land agreements with the government and in Gauteng, many areas of conservation interest are made of multiple small properties that are owned by different landowners which means a lot of effort is required in getting each landowner to sign up. Insight was also given into the roles of the various stakeholders and the relationship between the Gauteng Department of Agriculture and Rural Development (GDARD) and the landowners, and it was indicated that GDARD’s role is to provide guidance, education and resources when available to the landowners in order to manage their protected area. This study can be used as a baseline study for GDARD to measure the progress in conservation in terms of the landcover and ecological aspects at the site and to monitor any changes in landowner-GDARD dynamics.Item The effects of resource variability on the demographic rates of black and white rhinoceroses(University of the Witwatersrand, Johannesburg, 2023) Ndlovu, Latoya; Marshal, JasonGiven the importance of rhino survival and reproduction to conservation goals, the aim of the study was to investigate the effects of resource variability on the demographic rates of black (Diceros bicornis) and white (Ceratotherium simum) rhinos at Lapalala Wilderness. I used historical rhino-monitoring, rainfall and vegetation greenness data to investigate the vital rates of two rhino populations. I investigated population demographics (mainly density, growth rates, age and sex structure) and survival using stratified Cox models. Black and white rhino density peaked at 0.06 rhinos/km2 and 0.2 rhinos/km2 , respectively during the study period and was below the estimated maximum density for suitable rhino reserves. Average growth rate for the black rhinos was 4.784%, which was almost half of the white rhino’s rate of 8.861%. The survival of both species was stage-specific, and rainfall effects were similar for both species and age groups as low amounts of rainfall, which likely represent decreased forage availability, were associated with increased mortality risk. Decreasing greenness was also associated with increased mortality except with white rhino calves, where mortality increased with greenness. I suggest that this case might have been caused by their nutritional requirements: most grasses lose nutritional value as the season progresses (i.e., represented as increases in greenness values and so reduced access to high quality forage might affect mom’s body condition and her ability to produce nutritious milk, consequently resulting in increased mortality rates of calves. I also investigated the reproductive phenology (mainly conception and birth timing, age at primiparity and inter calving intervals) and birth sex ratios in relation to sex allocation theories. White rhinos conceived and calved at an earlier age compared to the black rhinos; mean age at primiparity for white and black rhinos was 9.448 years (8.467, 10.43) and 11.724 years (10.52, 12.927), respectively. Conceptions for both species peaked during the wet season and were associated with periods of high forage availability; however, births were asynchronous and occurred throughout the year. Effects of rainfall and greenness on age at first conception differed between species; the odds of having their first calf increased with rainfall, EVI and NDVI for white rhinos but decreased with EVI and NDVI for the black rhinos. Increases in wet-season integrated greenness during conception periods might indicate a shorter period of access to high quality forage for the black rhinos. Age at primiparity increased with density for both species because population density increases competition for resources, potentially making it difficult for females to accumulate the body mass and energy reserves needed to reproduce. Inter-calving intervals increased with rainfall, supporting the idea that excessive amounts of rainfall might result in lower forage quality, which then affects maternal body condition. In conclusion, vital rates of black and white rhinos are associated with resource availability as a function of environmental stochasticity and density, which in turn affects productivity and performance as climate change results in more variable conditions.Item The implications of mandible morphology and dental structure on the feeding ecology and predatory behaviour in Hyaenidae (hyenas) using geometric morphometric analyses(University of the Witwatersrand, Johannesburg, 2024) Nadioo, Riyanta; Iqbal, SafiyyahHyenas are often overlooked as being successful predators due to their scavenging behaviour. However, their morphological adaptations allow them to succeed in bone-cracking behaviour, an act that most carnivores are unable to achieve. Craniodental morphology influences carnivore performance, therefore understanding the functional morphology of carnivore mandibles would allow for the justification of Hyaenidae behaviour. This study investigates the morphological differences between the Hyaenidae mandible and large carnivore mandibles in Africa, as well as the differences in mandible morphology within the Hyaenidae family. This study uses a two-dimensional landmark-based geometric morphometric methodology to analyse morphological features on the carnivore mandibles and dentition to determine the morphological clusters linking the carnivore species, determine how the mandible morphology accommodates biomechanical needs, and to determine the implications that mandible morphology and dentition has on feeding ecology. The results of this study indicated that the sizes (PC1) of the carnivore mandibles were clustered according to their respective families (i.e. Hyaenidae, Canidae, and Felidae), however the shape (PC2) of the mandibles differed according to diet. The mandible morphology of the hypercarnivorous Hyaenidae displayed evident adaptations to osteophagy behaviour, including a thickened corpus, a large masseteric fossa, an anteriorly-displaced coronoid, and robust and blunt-like canines. The Proteles cristata, however, displayed mandibular adaptations to a hypocarnivorous diet. Ultimately, it was found that an increased resistance to bending forces and an increased area for muscle attachment on the mandible, directly relates to an increase in the Hyaenidae bite force, improving their feeding and hunting success.Item Personality profiles of the Namaqua rock mouse (Micaelamys namaquensis), the Mozambique thicket rat (Grammomys cometes) and the woodland dormouse (Graphiurus murinus)(University of the Witwatersrand, Johannesburg, 2023-09) Mampa, Nthabiseng; Linhsan, Emmanuel Do; Madikiza, KimPersonality is the variation in behaviour amongst individuals, which arises as a result of genetic differences and exposure to different environments. Although the term is usually associated with humans, multiple studies have found evidence for personality in other non-human taxa such as rodents, fish, reptiles, and primates, which ultimately showed that personality is ubiquitous. Personality determines how individuals react in different situations throughout their life, such as when they encounter stressors, interact with their conspecifics, prey and predators, how they select seeds and the distance to which they disperse, when displaying aggression, and when facing novel objects, their propensity to take risks, among other behaviours. Personality traits are most described using terms such as bold and shy, aggressive, docile, and avoidant. These terms relate to individual coping style, temperament, and correlated traits. Given the importance of personality, this study was aimed at studying personality in the woodland dormouse, Mozambique thicket rat and Namaqua rock mouse, in order to understand personality and how it varies among species and within species, i.e., between sexes. In consideration of the importance of genetic factors in the development of personality, it was expected that there would be differences among the three rodent species despite being exposed to similar environmental conditions. It was also expected that there would be differences between males and females within each species due to the influence of sex hormones on personality. Two standardised personality tests were conducted, namely the open-field and the novel object test to measure boldness, shyness, exploration, and avoidance when facing novelty by observing the frequency and duration of the behavioural responses exhibited during these tests. The study showed that rodents react to novelty by showing both shy and bold behavioural responses. However, the three species differ from each other in boldness and shyness. Males and females also showed differences in their behavioural responses to novelty. Overall, this study highlighted two strategies used for survival in nature. In consideration of this, it would be beneficial to preserve pristine forests to protect keystone structures that are crucial for preserving diversity in species and personality types. However, more studies on long-term trapping and correlation with personality tests could reveal more information on the personality profiles and their subsequent consequences.