Electronic Theses and Dissertations (Masters)

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The function of “plant biltong” collected by bush Karoo rats (Otomys unisulcatus)
(University of the Witwatersrand, Johannesburg, 2024) Sanweni Siyabong Patrick
Food 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.
Modelling current and future distributions of Warburgia species at continental (Africa) and local (South Africa) scales Samista Kim
(University of the Witwatersrand, Johannesburg, 2024) Rooplal, Samista Kim; Thompson, D.I.; Glennon, K.L.; Witkowski, E.T.F.
Warburgia is a genus of trees and shrubs that is greatly valued in Africa for its use in traditional medicine. The genus contains four species, one of which has two subspecies: Warburgia elongata, W. salutaris, W. stuhlmannii, W. ugandensis subsp. longifolia and Wugandensis subsp. ugandensis. Individuals are harvested primarily for their bark, which contains pharmacological compounds that are used to treat various ailments. Due to the high demand, species within the genus are overharvested throughout their range and have consequently become threatened by extinction. Warburgia salutaris, the pepper-bark tree, is the only species of the genus that naturally occurs in South Africa. Like its congeners, Wasalutaris is heavily exploited for its bark and has been listed as IUCN Endangered in South Africa. This dissertation, therefore, assesses the distributions of Warburgia species in eastern and southern Africa to identify new, potentially suitable areas to increase population numbers to aid in the conservation of the genus. The aim of the first part of the study was to assess the eastern and southern African distributions of Warburgia species. Species distribution models (SDMs) were created for the four Warburgia species and two subspecies, and the geographic distributions and key environmental predictors were identified for each taxon. Environmental niche analyses were also performed to understand whether the two subspecies of W. ugandensis should be considered as a single species in accordance with the ecological species concept. The second part of the study aimed to assess how the current South African distribution of W. salutaris will be affected by future climate change. An SDM was produced to assess the current distribution of W. salutaris in South Africa and identify its key predictor climate variables. The SDM was then extrapolated into the future (2070) using two climate change scenarios, RCP 4.5 and RCP 8.5, which are greenhouse gas emission scenarios that predict future climates under a probable and extreme scenario, respectively. Ecological niche analyses were also used to assess the degree to which W. salutaris’ climatic niche will change in response to the two climate change scenarios. Results showed that the distributions of Warburgia species are restricted and primarily influenced by climatic variables that likely impact their seeds’ and seedlings’ sensitivity to water stress and desiccation. Ecological niche modelling results show that the climatic niches of W. ugandensis subsp. longifolia and W. ugandensis subsp. ugandensis are identical and should therefore be considered as a single species according to the ecological species concept. The South African distribution of W. salutaris is fragmented and restricted. The species’ current and future distribution is influenced by its sensitivity to frost and the fact that it produces seeds that are susceptible to drying out. SDMs predicted that the distribution of W. salutaris will shrink in eastern Limpopo and in parts of Mpumalanga, but increase in eastern KwaZulu-Natal by 2070 under both climate change scenarios. Overall, this species was predicted to contract from the Indian Ocean coastal belt and grassland biomes and expand into the savanna biome. This study has expanded our knowledge of the distributions and environmental drivers of Warburgia species. It was found that in general, Warburgia species have restricted ranges that are likely governed by their sensitivity to desiccation at the seed and seedling stages. Climate change is anticipated to negatively impact the populations of many plant species, especially those in Sub-Saharan Africa. While the environmental niche of W. salutaris will remain stable, its geographical distribution was predicted to expand further in the savanna biome along the eastern coast of South Africa in response to climate change. Results from this study support pursuing different conservation techniques, including propagating Warburgia populations around the Great Lakes of Africa and Mt. Kenya and in western Limpopo and eastern KwaZulu-Natal for W. salutaris only. This study therefore emphasizes the importance of using SDMs as a baseline to inform effective conservation efforts for important medicinal plant species
Quantifying and Mapping Urban Ecosystem Services in Johannesburg, South Africa
(University of the Witwatersrand, Johannesburg, 2024) Friemond, Joseph
Modern cities face a wide range of challenges such as flooding and heat stress, which are driven by urbanisation and exacerbated by the impacts of climatic change. The ecosystem services provided by green spaces in cities have become a crucial element in addressing these challenges by supporting climate change mitigation and adaptation. The first step in maintaining and improving the supply of these services is their quantification and mapping. However, large knowledge gaps exist in South Africa and Johannesburg relating to the provision of urban ecosystem services. This study aimed to quantify the supply of three important urban ecosystem services (carbon storage, runoff retention and cooling) and map their distribution across the wards of Johannesburg. Carbon storage was quantified through field sampling of four urban forest types (roadside trees, parks, gardens and nature reserves) and the use of biomass equations. InVEST's urban flood risk mitigation model was used to quantify runoff retention, while cooling was quantified by deriving land surface temperatures from Landsat satellite imagery, which were then used as inputs for a cooling indicator. All three services were mapped across the wards of Johannesburg and then normalised for comparison. The results revealed that Johannesburg's urban forest stores 2.4 million tonnes of carbon, with significant differences in carbon storage between forest types. Johannesburg’s ecosystem services provide great value in mitigating urban challenges, retaining 20.9 million m3 of runoff during a 50 mm storm, and providing cooling services across most of the city. However, the supply of these services is unequal, with large spatial disparities between the northern and southern regions in the city. Numerous wards receive critically low supply of these services, making them vulnerable to the impacts of climatic change. The northern- central wards have optimal supply of all three services, highlighting synergies between services. Ultimately, these three services have immense value in the Johannesburg context and play key roles in supporting the city’s climate change mitigation and adaptation, through the multi-functional delivery of ecosystem services from urban green infrastructure. By mapping these services at the ward scale, our findings can be used to accurately inform authorities and decision makers of priority areas for intervention, as well as key areas for conservation
Heat-related health impacts: the responses of local governments to current and emerging heat extremes in the Gauteng province
(University of the Witwatersrand, Johannesburg, 2024) Riley, Bradley; Vogel, Coleen
In recent years, particularly during the last few summer seasons across the globe, there has been growing attention to the impacts of heat on human health due to unprecedented extreme heat and heatwave events. Cities and urban areas are especially at risk due to enhanced urbanisation and anthropogenic activities, leading to increased heat-related deaths and hospitalisation. Although many cities globally have developed adaptation approaches to address the current and emerging heat risks, heat adaptation strategies and planning in an African context have been poorly recognised despite the continent warming at double the rate of global temperatures. The high vulnerability of African cities due to poverty and poor socio-economic conditions, coupled with these temperature extremes, puts African societies at the forefront of future heat-related health impacts. South Africa is one African country that has recognised these growing heat risks and provided frameworks in their national and municipal policy and planning instruments. However, implementing and mainstreaming heat action across institutional structures remains a challenge. This study investigated the extent of current heat responses within three metropolitan municipalities in the Gauteng Province, South Africa, in the cities of Tshwane, Ekhuruleni and Johannesburg; to advance heat action within the local government and institutional structures of the province. In this mixed-methods research design, local officials from the municipality’s Environmental Health Department in each metro were interviewed, and a perception-informed assessment of vulnerability to heat-related health impacts was developed using Principal Component Analysis. Through interviews with the local Environmental Health Officials, it was revealed that extreme heat is not a priority within the Department, as heat action is neither mandated nor budgeted for, leading to a misalignment between policy and implementation. The ability of the Department to unlock its full potential for heat action is constrained by many challenges, highlighted by three central themes: (1) Resource capacity and the ripple effects, (2) Policy-implementation gap and (3) Interdepartmental coordination. Despite this, the Department has the potential to unlock many opportunities for future heat responses, highlighted by four central themes: (1) Existing systems: connecting the dots, (2) Power in unity: embracing a collaborative approach, (3) Mandated heat action and (4) Specialised heat action units. Additionally, this study demonstrated how a heat vulnerability assessment tool could be created using heat-specific socio-economic variables. This reveals the spatial distribution of vulnerability throughout the metro’s and highlights high levels of vulnerability within rural and informal settlements due to poverty, lack of access to resources and services and poor living conditions in these areas. Such an approach can offer valuable insights into the populations and areas most susceptible and at risk of heat-related health impacts, which can aid in developing targeted heat action responses and plans. Finally, this study contributes
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, Khuliso
The 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 report
The Relationship between Climate Variability, Household Food Security, and Child Nutrition in a Rural Social-Ecological System
(University of the Witwatersrand, Johannesburg, 2024) Xuba, Ntshika
Climate change is expected to impact livelihoods and human well-being, with rural areas potentially most at risk. The potential impacts of climate change on food security and nutrition in rural communities are particularly worrying. The socioeconomic disparities that exist in South Africa also drive disparities in food insecurity and undernutrition, with some people being affected more than others. Climate change is believed to threaten food security and nutrition, but only a limited number of studies in South Africa have evaluated the impact of climate change on changing household food security and, hence, the nutritional status of children under five years over time. Therefore, this study evaluated how climate variability (a proxy for climate change because of data limitations), specifically changes in precipitation, affected household food security and the nutritional status of children under five years between 2010 and 2021 in a rural social-ecological system in Mpumalanga Province, South Africa. It is the first of its kind to assess the impact of climate variability on the changes in household dietary diversity, the experience of hunger and the prevalence of child undernutrition while considering the impact of household socioeconomic characteristics in the context of a rural social-ecological system. This study is part of the SUCSES (Sustainability in Communal Social-ecological Systems) study, which aims to examine household livelihood and socioeconomic characteristics and how this influences child nutrition. SUCSES is nested within the MRC/Wits Agincourt Health and Sociodemographic Surveillance System site, which consists of 31 villages with households that rely on remittances and government social assistance as their main livelihood strategies. SUCSES, however, comprised 590 households at baseline in 2010. The children’s ages (months), heights (cm) and weights (kg) were available for each household. These measurements were used to calculate the children’s weight-for-height, weight for-age, and height-for-age, respectively, and to categorise the number of children who were wasted, underweight, or stunted according to the United Nations Children’s Fund’s nutritional standards. These numbers were then used to determine the prevalence and severity of wasting, underweightness and stunting. The household dietary diversity score (HDDS) and the household food insecurity access scale (HFIAS) are two food security indices developed using data from the SUCSES household survey questionnaires. These indices were used to quantify changes and trends in household food security status over time, while household socioeconomic characteristics, such as employment, asset ownership and household head, among others, were assessed as potential drivers of these households’ food security status. Then, utilising these food security and nutrition indices, the association between food security and child nutrition was examined. Seasonal precipitation trends were also quantified after converting rainfall averages to precipitation anomalies. The effects of precipitation were then assessed by comparing the variations in precipitation to indicators of food security and nutrition. Between 2010 and 2021, there was a significant rise in the prevalence and severity of wasting. Similar variations over time were seen in the prevalence and severity of underweightness (low weight-for-age). Stunting (low height-for-age) exhibited the highest mean prevalence and severity compared to wasting and underweightness, which fluctuated over time. The prevalence of stunting had no directional trend over the years, but the severity of stunting has increased dramatically, raising concerns because chronic poverty is a proxy for long-term undernutrition (e.g., stunting). Although the experience of hunger did not change, these households experienced a decrease in the diversity of diets over time. The diversity of diets was only associated with weight-for-height and weight-for-age in girls under five, despite popular research suggesting that food security is a significant contributor to nutrition. Therefore, households with less varied diets reported more wasted and underweight girls. Generally, rainfall stayed above normal between 2010 and 2014 while falling below average in the following years. However, the statistical analysis used in this study did not find evidence to support a downward or upward trend in precipitation over time. Changes in precipitation had little effect on the households’ experiences of hunger or how diverse their diets have been over time, but these precipitation patterns were associated with weight-for-height, with wasting (low weight-for-height) being more prevalent in below-average rainfall years. The study’s findings highlight the potential influence of climate change on nutritional status, regardless of changes in household food security, but the study’s low sample size may have limited this. Future studies need to build on this research, considering this study’s limitations, to gain a deeper understanding of the relationship between climate change, food security and child nutrition
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 initiative
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, Kirsten
The 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.
The effects of resource variability on the demographic rates of black and white rhinoceroses
(University of the Witwatersrand, Johannesburg, 2023) Ndlovu, Latoya; Marshal, Jason
Given 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.
The effects of elevated carbon dioxide on the secondary metabolites and biological activities in Moringa oleifera Lam. and Moringa peregrina Forssk
(University of the Witwatersrand, Johannesburg, 2023) Moloi, Thato; Dukhan, Shalini; Ramalepe, Phillemon; Risenga, Ida
Climate is crucial for the distribution and survival of medicinal plants as it can influence phytochemicals and regulatory hormones that are responsible for the normal growth and development, as well as their interactions with the environment. Thus, it is important to understand how climate change will impact these crucial plant compounds and hormones that play a significant role in the plant’s survival and development. With the increasing CO2 in the atmosphere, it is expected that climate change effects will be devastating to the world and Southern Africa. The present study intended to achieve two aims, the first being to investigate the impacts of elevated CO2 (eCO2) on the secondary metabolites and biological activities of two important Moringa species, Moringa oleifera Lam. (M. oleifera) and Moringa peregrina - (Forssk.) Fiori (M. peregrina). The second aim was to investigate how the use of M. oleifera leaf extract (MLE) based and commercial (PhytoStim®) biostimulants influence the productivity as well as the adaptability of M. oleifera and M. peregrina under elevated eCO2. The first set of three-month-old potted plant samples were exposed to 400 ppm (control), 600 ppm and 800 ppm for three months, respectively. The second set of plants were placed in the greenhouse and sprayed (foliar application) with 200 mL of M. oleifera leaf extract (MLE) and 200 mL commercial biostimulant PhytoStim® every second week for three months, respectively. The control samples were unsprayed. The third set of plants were exposed 600 ppm and 800 ppm (separately) and simultaneously sprayed with 200 mL of M oleifera leaf extract (MLE) and 200 mL commercial PhytoStim® (separately) every second week for three months to assess the influence of biostimulants on the adaptability of the Moringa species under eCO2. The control samples under 400 ppm were unsprayed. In this study, 80% methanolic extracts from all the above mentioned treatments of M. oleifera and M. peregrina were screened for 17 secondary metabolite groups (tannins, saponins, flavonoids, quinones, phenols, terpenoids, cardiac glycosides, coumarins, steroids, phlobatannins, anthracyanine, volatile oils, phytosterols, triterpenoids, proteins and amino acid, glycosides, carbohydrates) using qualitative methods. Quantitative analyses were performed to determine the total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC) and total proanthocyanidin content (TPAC). The antioxidant assays were performed to determine the reducing, scavenging and chelating abilities against DPPH, H2O2 and metal (Iron) chelating. The antimicrobial activities against gram negative Escherichia coli and gram-positive Staphylococcus aureus, Streptomyces albulus were assessed by using the agar well diffusion assay. In the control samples, out of 17 screened secondary metabolites, four (phytosterols, volatile oils, anthocyanin and phlobatannins) were not detected in both species’ extracts. On average, M. peregrina showed higher total content of tannins, phenolics, flavonoids and proanthocyanidins. M. peregrina showed stronger antioxidant activity against iron chelating and H2O2, whilst M. oleifera showed stronger antioxidant activity against DPPH. Both M. oleifera and M. peregrina extracts displayed an acceptable bacterial growth inhibition capability (ZOI ≥10 mm) with only S. albulus being resistant to the control of M. oleifera. Qualitative phytochemical analysis indicated the presence of secondary metabolites such as tannins, saponins, flavonoids under 600 ppm and a slight decline under 800 ppm in both species. The quantitative analysis indicated an increase in the total content of phenols, flavonoids (flavanols), tannins, and proanthocyanidins. An increase in CO2 resulted in an increase in the activity of antioxidants and antibacterial for both species. On average, Moringa peregrina showed higher accumulation of secondary metabolites, higher antioxidant and antibacterial activities in comparison to Moringa oleifera. The foliar application of MLE and PhytoStim® showed an increase in some secondary metabolites and decrease in metabolites such as tannins and phenols in M. oleifera. The application of biostimulants (MLE and PhytoStim®) also resulted in an increase in TPC, TTC and TPAC in M. peregrina, with a decline in total contents of these compounds in M. oleifera. However, the decline did not negatively impact both species' pharmacological abilities (antioxidant and antimicrobial activities), as they exhibited stronger antioxidant and antimicrobial activities when compared to the untreated plants (control samples). The use of the above mentioned plant based biostimulants resulted in an enhanced adaptability as indicated by the increase in the accumulation of selected screened secondary metabolites plant samples that exhibited signs of stress. The higher accumulation of secondary metabolites was observed under 600 ppm, in combination with PhytoStim® for either species. The combined CO2 and biostimulant treatments improved the total phenolic content (TPC) of both M. oleifera and M. peregrina significantly, with M. oleifera showing higher TPC content when compared to M. peregrina. On average, both M. oleifera and M. peregrina exhibited lower total flavonoid content (TFC), total tannin content (TTC) and total proanthocyanidins (TPAC), with M. oleifera showing higher contents of the above-mentioned phytochemicals in comparison to M. peregrina. The study also highlighted a decline in biological activities for all treatments, with the controls showing higher biological activities for both species. In the three antioxidant assays conducted, the leaf extracts of the controls had significant lower IC50 values for DPPH and H2O2, when compared to the stressed M. oleifera and M. peregrina. Antimicrobial assays also showed no significant difference in the bacterial inhibition capabilities of M. peregrina and M. oleifera under 600 ppm and 800 ppm with either biostimulant application. M. peregrina and M. oleifera controls showed high ZOI for the selected bacterium. The study has demostrated that biostimulants (MLE and PhytoStim®) enhanced the adaptability of both species under potential stress coursed by eCO2. The present study has demonstrated that the exposure to elevated CO2 could alter the accumulation and biological processes (such as antioxidant activity and antimicrobial activity) in both M. oleifera and M. peregrina. Moringa peregrina exhibited more tolerance to elevated CO2 when compared to Moringa oleifera and showed higher antioxidant and antimicrobial activity which might be attributed to the stronger presence of phytochemicals such as flavonoids, phenols and tannins. The data also suggests that both Moringa oleifera and M. peregrina can adapt to high levels of CO2 concentrations (~600 ppm), however, as medicinal plants, it might be difficult to sustain the acclimatisation and tolerance due to membrane oxidation and DNA damage. Therefore, foliar application of the biostimulants could enhance the adaptability and productivity of both species under high levels of CO2. This study may contribute towards better planning on conservation efforts to improve the chances of survival of the Moringa oleifera and M. peregrina and could aid with food security.
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, Safiyyah
Hyenas 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.
Water Quality Monitoring of Biological and Chemical Pollutants into the Wakkerstroom Wetland
(University of the Witwatersrand, Johannesburg, 2024) Klinkert, Celine; Scholes, Mary
Wetlands are among the most important ecosystems in the world due to the array of ecosystem services that they provide, such as flood attenuation, ground water restoration, water filtration and pollutant removal, climate change regulation and reducing erosion. The Wakkerstroom wetland in the Mpumalanga Province South Africa, plays a major role in improving downstream water quality. The wetland is threatened due to excess nutrient loading and microbiological contaminants entering the water column from a sewage ground runoff and a malfunctioning wastewater treatment plant. This study aims to determine the water quality and nutrient removal from the wetland by assessing chemical parameters and coliform and E.coli contamination as faecal indicators. Eight sampling sites were chosen along the length of the wetland, and water sample collection occurred once a month between August 2021 and July 2022. The results showed a neutral pH between 6 and 8 with no spatial or temporal significant differences. The mean Total Dissolved Solids (TDS) ranged between 50 – 145 mg/L. The mean nitrate concentrations (NO3-) ranged between 1.50 and 7.00 mg/L across the sampling sites. During the sampling period, a net total of 17.53 mg/L of nitrate was removed from the water column by the wetland. The mean phosphate concentration (PO43-) ranged between 0.40 – 1.40 mg/L, showing a total net removal of 2.14 mg/L during the sampling period. Coliform abundance was high closest to the wastewater treatment plant and sewage runoff and decreased along the length of the wetland, with an estimate removal of 1.17, calculated from a qualitative colour changing scoring system. E.coli bacteria was present in the wetland at all of the sampling sites between March 2022 to July 2022. This study resulted in the confirmation of a healthy, functioning wetland system where the wetland is able to reduce excess nutrients and coliform contamination. The wetland water quality shows similarities to studies conducted on wetlands in South Africa. The wetland is still under threat through possible reduced functioning as a result of excessive exposure to untreated domestic and sewage waste. A need exists for improved management and more stringent standards of water quality control from the wastewater treatment plant to reduce the risk of wetland degradation through excessive sewage exposure.
Seasonal abundance and diversity of mites in Coffea arabica L. at Beaver Creek Coffee Estate, South Africa
(University of the Witwatersrand, Johannesburg, 2023) Chikomo, Nontobeko Natasha; Situngu, Sivuyisiwe
The presence of multiple species of mites inside the leaf domatia of Coffea arabica is well documented by various studies. This study examined the influence of seasonal changes on the abundance and diversity of mites in the leaf domatia of Coffea arabica. The study furthermore documented the species of predatory mites that were associated with coffee. The results of the study showed that there was a significant variation in the abundance of mites due to changes in season. Mite counts were significantly higher in spring followed by autumn and lowest in summer. There was no correlation between the number of mites and temperature and relative humidity. Therefore, this study could not establish what drives the seasonal changes in the mite populations and we postulate that this was because we did not measure the microclimate of the individual trees we sampled. This would have given us more accurate data on the temperature and relative humidity experienced by these mites. The Shannon-Weiner Diversity Index was found to be highest in summer and lowest in winter. The Phytoseiidae, Tydeidae, Stigmaeidae, and Tenuipalpidae were found to be the predominant families in this study. This study is one of the few studies in South Africa to directly investigate the effects of seasonal changes in mite abundance, and could potentially open avenues for further research, particularly on what seasonal parameters drive the mite population changes. We recommend that future studies use Ibuttons to get a true measure of the climatic variables that are experienced by the mites sampled at a tree level
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, Kim
Personality 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.
The Impacts of Ungulate Foraging on Small Mammal Diversity in a Protected Site and Livestock Grazing Site
(University of the Witwatersrand, Johannesburg, 2023-09) Dlamini, Sifiso; Linhsan, Emmanuel Do; Madikiza, Kim
Vegetation cover and food availability are important determinants of how favourable an area is for the settlement of animals, especially small mammals such as rodents, which rely heavily on vegetation for protection against predators and access to food. This study investigated the impact that ungulate foraging activities (both domesticated and wild) have on small mammal diversity in two Short Euphorbia Thicket habitats within the Albany Thicket Biome: a natural site in the Great Fish River Nature Reserve and an adjacent livestock grazing site belonging to Kwandwe Private Game Reserve. Trapping was carried out over 7-day/7-night trapping sessions during the wet and dry seasons at each site, with grids of 10 x 10 traps with a 10 m spacing. Over a total of 5,600 trap nights/days, 272 unique individuals of six small mammal species (4 rodents, 1 shrew, and 1 sengi) were captured. Habitat (i.e., the 1 ha area studied on each site) and microhabitat differences were assessed for the two study sites using plant cover at different heights, the number of bushes, the presence of Euphorbia bothae, as well as the amount of bare ground and rocky surfaces around each trap station. Between the habitats, vegetation in all the height categories differed significantly during each season, while the number of bushes did not differ. The microhabitats also showed seasonal variation, with the dry season having less vegetation cover than the wet season. Although greater vegetation cover was recorded during the wet season, small mammal abundance was low, as were species richness and diversity. It was the dry season that had the higher small mammal abundance for both sites, with the protected site having four times the abundance (across all species) of the livestock grazing site. Small mammal diversity was, however, highest at the livestock grazing site, where the species were evenly represented, whereas the protected site had unevenly represented species with a lower diversity. It is concluded that both domesticated and wild ungulate foraging activities, as well as seasonal changes in climatic conditions, alter vegetation cover. This determines whether a habitat is conducive for small mammals, thereby driving their richness, abundance, and ultimately diversity within a habitat.
Employee Sentiments Concerning Workplace Greening
(University of the Witwatersrand, Johannesburg, 2023-09) Khorommbi, Phumudzo; Moolla, Raeesa
For centuries, people have continuously impacted the environment, resulting in an exponential rise in environmental problems and deterioration. In the quest to find solutions, business organisations have employed or tried to institute greening programmes, such as promoting waste at source and installing solar panels. However, it is essential for people, specifically in occupational settings, to see this as a need - for greening programmes to be effective. To this end, this study aimed to identify the elements that drive individuals to conduct environmentally responsible behaviours at work. This qualitative study collected data by administering surveys to research participants. Information related to eco-helping, eco-initiatives and eco-civic engagement was collected by administering surveys to local contractors at the PepsiCo site in Kempton Park, Johannesburg. The survey amassed 70 responses during October 2023. The study found that gender was an important indicator of pro-environmental behaviour, and that age affected a person’s inclination to act pro-environmentally. As this study relied on proclamations of good environmental intentions from participants, future studies should test this hypothesis in the field to quantify its success.
Functional feeding groups of mayfly nymphs (Ephemeroptera) in South African rivers of the North West and Limpopo Provinces
(University of the Witwatersrand, Johannesburg, 2024-02) Bossman, Esi H.; Harrison, James du G.; Woodford, Darragh J.
Researchers, primarily in the Northern hemisphere, have extensively studied mouthpart morphology and dietary variability in Ephemeroptera (colloquially called mayflies). Ephemeroptera are key primary consumers in rivers around the world and are used as aquatic biomonitoring indicators due to interspecific variation in ecological tolerances that make them good indicator taxa. Cummins (1973, 1974) created a functional feeding groups (FFG) classification system, based on northern hemisphere macroinvertebrates, as a universal tool to functionally categorise organisms based on their primary feeding mode within their habitat. The FFG classification system is useful in identifying interrelations between structural and functional components of an ecosystem. The aim of this study was to contribute knowledge on FFGs for particular mayfly species, in the southern African savanna biome, through mouthpart morphology and gut content analysis. Four study sites were sampled from the Magaliesberg (M) and Waterberg (W) catchments. There were three species studied, namely Afroptilum parvum (Family Baetidae), Afronurus barnardi (Family Heptageniidae) and Elassoneuria sp. (Family Oligoneuriidae). These species’ mouthparts were dissected and their macro- and microstructures were prepared for viewing with Scanning Electron Microscopy (SEM) and light microscopy. Micrographs and images showed variation in mouthpart morphology between all three species, with special attention to the labia and maxilla microstructures. The identification and description of microstructures that differentiate mayfly species (and the adaptations of these appendages to facilitate food uptake and ingestion) are important to address knowledge gaps regarding mayfly mouthpart morphology. A Principal Component Analysis (PCA) showed distinct grouping of the three species, with mandibles and maxillary palps showing the most variation between species. After analysis, the following feeding groups were assigned: Afroptilum parvum is a collector-gatherer feeder, Afronurus barnardi is a brusher-scraper feeder and Elassoneuria sp. is a filter feeder. This study showed, in part, that the Cummins’ (1973, 1974) classification categories were too broad for classifying organisms from a South African savanna stream. However, it is a good foundational starting point for region specific FFG classification systems. Thus, it is recommended to use the classification system Cummins created as a starting point for classifying organisms into FFGs with an initial definition that can be expanded upon to create individual classification systems for different localities.
The influence of plant phenolic compounds on the host range of Coniatus tamarisci Fabr. (Coleoptera: Curculionidae): a potential biological control agent of invasive Tamarix L. (Caryophyllales: Tamaricaceae) Taxa in South Africa
(University of the Witwatersrand, Johannesburg, 2022) Hatile, Sivenathi Luvolwethu; Byrne, Marcus; Mayonde, Samalesu
Tamarix L. (Caryophyllales: Tamaricaceae) are halophyte species that are native to Eurasia, North Africa, and southwestern Africa. These phreatophyte trees or shrubs have become prominent and widespread invaders in North America, South America, Australia, and South Africa. In South Africa, the Alien and Invasive Species regulations of the National Environmental Management: Biodiversity Act 2014 (NEM:BA) has classified invasive Tamarix as category 1b invader, which require control. Thus, three potential biological control agents have undergone laboratory-based host-specificity trials for the long-term sustainable control of Tamarix. The first two of these biocontrol agents, Diorhabda carinulata (Desbrochers.) (Coleoptera: Chrysomelidae) and Trabutina mannipara (Hemprich & Ehrenberg) (Hemiptera: Pseudococcidae), both failed the laboratory-based host-specificity trials because they completed their life cycle on the indigenous T. usneoides E. Mey ex Bunge. Previously, potential biocontrol agents were selected based on their native distribution and the phylogenetic relatedness of the invasive weed to indigenous nontarget species. However, it has recently been suggested that secondary metabolites also play a major role in insect host selection, and thus should be considered to improve the selection criteria of potential biocontrol agents. The current study is based on the third biocontrol agent that recently underwent laboratory based host-specificity trials in South Africa, Coniatus tamarisci (Fabr.) (Coleoptera: Curculionidae). This was in conjunction with an analysis of the potential influence Tamarix phenolic compounds have on insect host selection. The results show that although C. tamarisci could complete its’ life cycle on T. usneoides, the weevil had a low affiliation/risk associated with the indigenous Tamarix taxon. This advocates for the conduction of open field host-specificity trials, which will allow for a better understanding of C. tamarisci behaviour in a natural setting. Regarding phenolic compounds, three phenolic acids have been identified as being significantly prominent in T. usneoides compared to the invasive Tamarix taxa present in South Africa. These are gallic acid, dehydrodigallic acid, and syringic acid. These compounds are associated with protection from plant herbivory, which could explain the behaviour of C. tamarisci when exposed to and reared on T. usneoides.
Evaluation of the JSE’s environmental reporting requirements of South African listed companies
(University of the Witwatersrand, Johannesburg, 2024) Hariram, Viratha; Schwaibold, Ute
Through its mandatory environmental reporting requirements, the Johannesburg Stock Exchange (JSE) plays a pivotal role in the private sector to align to Environmental, Social and Governance frameworks and disclose information of a company’s environmental priorities and performance in addressing areas of concern. While there are attempts to safeguard the environment from damage and degradation, it is unclear if this framework is suitable at appropriately addressing the environmental areas of concern facing South Africa. In order to evaluate the JSE’s environmental requirements on listed companies, this study aimed to identify the local and global environmental priorities via the South African State of Environment Outlook Report (local view), National Development Plan (local view) and Sustainable Development Goals (global view) and thereafter determine if the Global Reporting Initiative, the only set of mandatory environmental requirements of the JSE, was adequately addressing the indicators they outlined. Furthermore, using a scoring system from zero to four, the study evaluated the alignment of ten randomly selected JSE listed companies against the requirements of the Global Reporting Initiative to note their level of adherence and alignment to the South African State of Environment Outlook Report, National Development Plan and Sustainable Development Goals. The results indicate that the Global Reporting Initiative (GRI) covers 73% of environmental priorities discussed in the South African State of Environment Outlook Report, National Development Plan and Sustainable Development Goals. Of the total 74 indicators of environmental concern identified from the three reports, the GRI did not require disclosure for 20 indicators. Only three indicators that were required to be disclosed by the GRI had scored a four on the rating scale due to it being an integrated disclosure that takes into account one or more other related environmental categories. The evaluation of the sampled listed company’s adherence to the GRI via their sustainability reports and integrated annual reports indicated that none of the companies had provided sufficient disclosures to meet the requirements of the GRI. 80% of the sampled listed companies made a strong alignment to the Sustainable Development Goals in their sustainability reports and / or integrated annual reports. A shortcoming of the JSE that was stated by all four sustainability experts interviewed was the lack of enforcement for listed companies to make quality and comprehensive disclosures or accountability expected from listed companies. There is no formal process of review or consequences for listed companies who do not comply.
The impacts of landfill management site A on grass, soil, and surface water: a preliminary study in KwaZulu-Natal, South Africa
(University of the Witwatersrand, Johannesburg, 2024) Ndobe, Florence Nonhlanhla; Schwaibold, Ute
Environmental pollution is a major global challenge, and the prime pollution source is anthropogenic activities, including industrial and waste management activities amongst others. Heavy metals are known pollutants released due to landfill operations and pose a problem in the terrestrial ecosystem, aquatic ecosystem, and human health through exposure. There are well-documented studies of heavy metal contamination and its impact on soil, groundwater, and surface water, and plants in general, yet the characteristics of contamination can be unique to each landfill site. This study aimed to investigate the potential impacts of toxic waste leachate from a landfill site in KwaZulu-Natal on the surrounding grasses, soil, and surface water. The methodology involved two broad approaches to data collection, a quantitative approach which entailed collecting grass, soil, and surface water samples near the landfill site to determine the levels of heavy metals (As, Cd, Cr, Cu, Pb, and Zn) and their potential impacts, and a qualitative approach which entailed interviews with nearby residents to investigate the community’s perception and awareness of health and environmental risks associated with living close to the landfill site. Three sampling sites downhill from the landfill site were sampled, namely the central stream site (adjacent to the leachate/storm water dam one, downstream site (storm water dam two), and control site-upstream (northbound), and heavy metals concentration varied significantly between sample types and sites. In almost all cases, the heavy metals exceeded WHO permissible limits. Contamination factor (Cf), pollution load index (PLI), and ecological risk index (Ri) were also calculated and based on these, in grass Cr, Cu, Pb, and Zn contributed to very high contamination in the central stream area, whereas downstream, Cd showed very high contamination, suggesting a very high ecological risk. In soil, contamination levels and risk were mostly moderate to low. In surface water, Pb contributed to high contamination while downstream water was mostly moderately contaminated. The most common challenge highlighted by community members during interviews were air pollution, water pollution, dust, and noise nuisance. For all communities, headaches are the most commonly reported, followed by asthmatic conditions and respiratoryrelated distress. The results indicated that people living 1-2km away from the landfill site were likely more exposed to health and environmental-related risk than people living 3-5km away from the potential polluting sources. iii In conclusion, high heavy metal contamination in soil, surface water, and grass suggests a likely leachate leakage and/or the dispersion of other related pollutants in the surrounding environment, which requires a further in-depth investigation to find the signature source of pollution.

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