Electronic Theses and Dissertations (Masters)

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The impact of nickel and chrome mine tailings on the growth of Hibiscus cannabinus and Linum usitatissimum and a preliminary assessment of their applicability as economically beneficial phytoremediation species
(University of the Witwatersrand, Johannesburg, 2023-07) Campbell, Tiago Roberto; Furniss, David; Scholes, Mary
Current and previous mining activities in South Africa have caused various environmental, human health and societal impacts. This has led to the formation and enforcement of legislation regarding the rehabilitation of active, closed and abandoned mines in South Africa. The requirements contained in this legislation include rehabilitation, skills transfer, job creation and development of post mine land use regarding active, closed and abandoned mines. A common impact of mining activities is the contamination of soils with various metals. The process of phytoremediation has demonstrated potential in the remediation of metal contaminated soils. Plant species commonly utilised in this process are hyper accumulators, which can translocate and accumulate high concentrations of various metals from soils into their biomass. However, large areas of previously economically productive land become underutilised when hyper-accumulators are used for phytoremediation. Economically valuable fibrous plant species have demonstrated potential in their use as phytoremediation species. This presents an opportunity in which economically valuable plant species could be utilised in phytoremediation applications on active, closed and abandoned mines in South Africa. Thus, the aim of this research was to assess the ability of Hibiscus cannabinus and Linum usitatissimum to grow in and extract metals from soil contaminated with nickel and chrome mine tailings. Furthermore, the concurrent use of H. cannabinus and L. usitatissimum as phytoremediative and economically beneficial plant species was determined. Normal (non impacted), rehabilitated (previously impacted) and tailings (impacted) soil treatments were collected and used from the Onverwacht tailings storage facility of Nkomati Nickel mine. Hibiscus cannabinus and L. usitatissimum were cultivated in each soil treatment in greenhouse conditions over a six-month period. Multiple plant growth parameters were recorded at monthly intervals. The amount (mg) and concentration (mg/kg) of Mn, Zn, Ni, Cu, Cr and Co contained within plant tissue samples at the end of the six-month period was determined. The area (ha) of land categories available for H. cannabinus and L. usitatissimum cultivation onsite was determined using Sentinel 2B satellite imagery and supervised image classification. The measured and expected total yield (t), yield value (R), profit/loss margin (R) and amount (g/ha) of Mn, Zn, Ni, Cu, Cr and Co extracted through cultivation of H. cannabinus and L. usitatissimum onsite was determined. The growth of H. cannabinus and L. usitatissimum cultivated in rehabilitated soil was severely impacted. While growth of each species exhibited minimal differences between those cultivated in normal and tailings soil. Hibiscus cannabinus consistently exhibited greater growth than L. usitatissimum. Both species demonstrated the ability to accumulate varying amounts and concentrations of each of the tested metals in their total, above and below ground components. Both species consistently accumulated increased amounts and concentrations of Mn and Zn. Those cultivated in tailings soil exhibited increased accumulation of Cr. Linum usitatissimum generally accumulated metals at higher concentrations than H. cannabinus, however, minimal differences in the amount of metal accumulated between species were observed. Based on the measured yield cultivation of each species onsite would result in economic loss and generally low metal extraction. However, based on the expected yield, species cultivation onsite, in normal and tailings soil, would result in economic gain and generally high metal extraction. Hibiscus cannabinus and L. usitatissimum exhibited phytoremediative and economic potential. Aspects of the current state of mine impacted land in South Africa and the requirements of rehabilitation enforced through South African legislation could possibly be addressed through the application of H. cannabinus and L. usitatissimum for mine rehabilitation strategies.
Using the South African Diatom Index (SADI) to determine the present ecological status of the Crocodile River, Kruger National Park
(University of the Witwatersrand, Johannesburg, 2023-08) Thamae, Seeng; Snow, Gavin; Parrini, Francesca
The Crocodile River in the Mpumalanga Province of South Africa is a river of great economic significance, while providing support to the surrounding aquatic and riparian ecosystems through ecological processes of chemical, hydrological, and geomorphological nature. This river forms part of the Inkomati River Basin, which serves as a transboundary basin shared between the Republic of South Africa, Mozambique and Eswatini. The importance of the effective management of transboundary water resources, from an African perspective, cannot be stressed enough due to the water-scarce nature of the Southern African region, particularly South Africa. Incorporating Integrated Water Resources Management (IWRM) and Strategic Adaptive Management approaches into the governance of water resources can aid in the protection of both the quality and quantity of the country’s freshwater reserve. Good governance of water resources is essential in the conservation of aquatic and riparian ecosystem biodiversity, as well as meeting the basic human needs reserve, which is essential to meet people’s daily drinking, food preparation and personal hygiene requirements. The Crocodile River is not immune to pollution of anthropogenic origin, such as urbanisation, mining, agriculture, and industrial by-products. The above mentioned constitutes some of the direct and indirect results of large-scale stresses that are exerted on a river system, mainly owing to environmental factors such as landscape, demographic, atmospheric and hydrologic changes. A few practical examples of these factors include changing population dynamics and resultant land-use requirements, accompanied by compromised riparian vegetations arising from the altered land-use. All this necessitates the regular monitoring of the quality of water in this river system. The outcome of regular river monitoring is essential to the protection of this resource through regulation and policy. The use of physico-chemical parameters to determine the health of the Crocodile River has assisted in identifying compromised aquatic and riparian ecosystems and ultimately recommending relevant mitigation strategies necessary in maintaining an acceptable standard of water quality. Incorporating biomonitoring techniques, wherein aquatic microorganisms are used to infer water quality, as a tool to assess the health of a river ecosystem has proven useful, mainly due to the sensitivity of periphyton assemblages (algae, cyanobacteria, diatoms) to changing river conditions, based on nutrients and physico-chemical parameters. The use of these organisms, in bio-assessments of aquatic ecosystems has been key to overall river health monitoring. This study highlights how diatoms, through their published ecological data, can contribute to the Resource Directed Measures method of determining the Present Ecological Status of a river, using the Crocodile (East) River as a case study. The current study was developed to assess the ecological category of the Crocodile River, along the southern boundary of the Kruger National Park. Four sampling sites were identified for the study, from which water samples were collected during September 2019, October 2019, and March 2020 sampling sessions. The basis of this was to investigate the changes in diatom communities and dominant microphytobenthos (MPB) groups (based on the tolerance to fluctuating environmental conditions amongst the various species) in response to the spatio-temporal changes in the quality and quantity of water at the four sites throughout the study period. These results were then compared to past studies to determine if there has been a change in river health over the past decade. Physico-chemical variables were measured in situ using a YSI Professional Plus (Pro Plus) multi-parameter instrument, which included temperature, pH, electrical conductivity, and dissolved oxygen. The benthic microalgal biomass of cyanobacteria, green algae and diatoms was quantified from the fluorescent signatures of the groups in situ using a bbe BenthoTorch. The bbe BenthoTorch is a hand-held apparatus that uses in situ quantification of chlorophyll-a fluorescence as an index of benthic algal biomass. The diatoms present in the samples were later prepared and isolated for microscopic identification and individual counts. The Relative Abundance (RA%) of dominant diatom species and the ecological category of each sampling site was determined using OMNIDIA software based South African Diatom Index (SADI). Ecological categories using the SADI range from A (good quality) to E (bad quality). Data analyses include the use of ordination plots (CCA and PCA) to evaluate the response of the dominant diatom species to changing environmental variables and the interspecific relationships between the diatom species in each assemblage, based on their ecological requirements. The study revealed that the ecological status of the Crocodile River when compared to previous studies had remained the same; C (moderate quality). This finding supports the use of the South African Diatom Index (SADI) in determining the Present Ecological State of the Crocodile River, in the Kruger National Park. There have been similar studies in other river systems within the Kruger National Park, wherein diatoms (specifically diatom-based index scores) were used to infer the water quality, at the time, in comparison to historic / benchmark water quality parameters. These studies were conducted in the Olifants, Letaba and the Sabie rivers of the park. The viability of these studies is motivated by benthic diatoms being particularly sensitive to changes in water quality, making them an ideal indicator of river health that is complementary to the current suite of biomonitoring tools. This method has immense potential in South Africa, provided that more focus is placed on diatoms and investment made in capacitating researchers and diatom taxonomists with the skills to perpetuate this vast field of study.
Assessment of the Environmental Authorisation Processes and Mining Right Applications for Improved Environmental Outcomes
(University of the Witwatersrand, Johannesburg, 2023) Antoniades, Maria; Watson, Ingrid
This study investigates alignment of South African mining right and environmental authorisation application processes to determine their adequacy in catering for optimised early mine planning seeking to achieve enhanced environmental outcomes. First the legislative requirements for mining right and environmental authorisation applications are evaluated. Results are critically analysed, including an assessment of process alignments and disjunctions. Secondly, integration of the application study processes in practice are investigated. The practical implications of the application requirements are qualitatively examined through key informant and case study analysis. It is shown that integrated planning is not a legislated requirement nor readily adopted by proponents. Environmental planning conforms to technical outputs as tick-box exercises rather than being iterative and co-operative. Workstreams misalignments result in poor planning to the detriment of environmental outcomes. Finally, a practical guidance is presented for early integrated study processes aimed at meaningful project design through parallel planning to optimise environmental results.
Comparative Analysis of Water Hyacinth Efficiency as Biosorbent and Phyto remediating Plant for Removal of Lead (Pb) Water Contaminants
(University of the Witwatersrand, Johannesburg, 2023-08) Nwagbara, Victor Uzoma; Parrini, Francesca; Newete, Solomon
One of the major problems facing the modern society is the issues of water contamination. The ability of aquatic plants to serve as both heavy metal biomarkers and phytoremediators has been advocated for many years. The purpose of this study was therefore to compare the efficacy of water hyacith as a biosorbent and phytoremediating plant for removal of lead from contaminated waters. Dry and fresh water hyacinth biomass were exposed to Pb-contaminated water at different time intervals of 1, 7, 14 and 21 days. The results showed that with the increase of the exposure time, the Pb removal capacity of the plant biomass also increased. The Pb water concentration in day 1 and day 7 were significantly different from those in day 14 and day 21 which were not significantly different from each other. The average Pb removal from the Pb-treated waters for the different time exposure of 1, 7, 14 and 21 days in the fresh water hyacinth biomass were 40%, 56%, 78 % and 79%, respectively, the highest reduction being in the latter. The biomass of the freshwater hyacinth roots had the highest Pd concentration compared to the shoot. On The other hand the average Pb removal by the dry water hyacinth biomass were 78.9 %, 78.5%, 78.3 % and 78.3% for day 1, 7, 14 and 21 respectively, showing no significant difference between the different time series exposure. This suggests the instant adsorption of Pb by the dry plant material from the first day of exposure, after which the active sites for adsorption saturates to accommodate any further Pb ion uptake. There were some plant stresses such as leaf chlorosis, and significant decrease in biomass weight and length of leaf-2 petiole in the lead-treated fresh water hyacinth plants compared to the controls (Pb-free water hyacinth plant). Thus, this study confirms that the largest removal by the dry water hyacinth biomass, occurred in the first day as opposed to the last day (day 21) by the freshwater hyacinth biomass.
Characterizing microclimates as potential thermal buffers for reptiles, birds, and mammals in an arid-zone environment
(University of the Witwatersrand, Johannesburg, 2023) Warner, Grace M.; Alexander, Graham J.; Fuller, Andrea
Aridification, increases in air temperatures and frequency of extreme weather events, such as heat waves, are predicted to intensify under climate change, suggesting dire consequences for dryland animals. Microhabitats may buffer dryland animals against the changing climate, yet microclimatic data remains scarce from Africa and arid regions. The distribution, abundance, and thermal buffering capacity of five microhabitat types (burrows, nests, rock crevices, tree hollows and vegetation) were investigated across three habitat types (dunes, plains, and mountains) in the Kalahari. The distribution and abundance of microhabitats were assessed via strip transects, while thermal buffering capacity was evaluated by comparing miniature black globe temperatures from 70 representative sheltered microhabitats with 12 localised exposed-site microhabitats. The data generated have provided a baseline measure of the abundance and distribution of microhabitats in the Kalahari and have produced a year-long fine-resolution microclimatic thermal dataset. Microhabitat types and abundance were found to differ per habitat type and across topographic gradients. Abiotic drivers, such as soil type and fire frequency, along with drivers such as biotic community composition, were highlighted as potential causes of these microhabitat distribution patterns. Burrows were the best buffered microhabitat across all tested temporal and spatial gradients, providing an average maximum decrease of -29.5 ˚C during the day, and an average maximum increase of 20.1 ˚C during the night. Well-buffered microhabitats were rare within the field-site, whereas some of the poorest buffering microhabitats (Vegetation) were abundant and widespread. Thus, competition for well-buffered microhabitats may increase under climate change, whilst the risk of traversing large distances between microhabitats may become too great for smaller animals as exposure risk to extreme temperatures increases. Furthermore, birds and large mammals may likely be at a high risk of extreme temperature exposure, as their size and structural adaptations may restrict them from access to well-buffered microhabitats. Therefore, the need for the concurrent assessments of microhabitat distribution, abundance and buffering capacity in future species vulnerability assessments is highlighted, as it is the combination of these factors that are likely to impact population viability under climate change.
Factors affecting mammal utilisation of non-wildlife railway underpasses within the Greater Kruger, South Africa
(University of the Witwatersrand, Johannesburg, 2023) de Villiers, Hannah; Parrini, Francesca; Teren, Gabriella
Railways are an integral component of sustainable transport systems, but cause significant impacts to biodiversity, primarily through wildlife-train collisions and the habitat fragmentation created in the landscape. Crossing structures (CSs) for wildlife are the key mitigation measure for these adverse impacts, which will be critical throughout Africa, where 55,000 km of new railway lines are predicted to cut through hundreds of protected areas. For the first time in southern Africa, mammal usage of railway underpasses that were not designed to facilitate wildlife movement was studied using camera traps in the Greater Kruger National Park, South Africa. This study demonstrates that 70% of the terrestrial medium and large mammals species present in the area used at least one non-wildlife CS during the study period, with a total of 1,823 usage events by 33 species. Twelve medium to large African mammal species used underpasses regularly, improving the permeability of the railway line for these species. A viaduct design was characterised by almost four times the usage rate of a typical box culvert and was used by twice as many species, including megaherbivores and mesoherbivores, whereas box culverts supported a smaller number of species, of which the majority were predators. Species most affected by rail collisions in the study area were mostly herbivorous and seldom used non-wildlife underpasses. These results indicate that a railway line with only drainage culverts and the occasional viaduct is not effective in providing adequate safe crossing structures for megaherbivores and ungulate mesoherbivores. Contrary to expectations, vegetation and environmental factors influenced mammal usage of box culverts more than structural dimensions. Ensuring that there is high visibility through the structure, with less herbaceous cover and more woody cover outside of entrances, is likely to enhance culvert usage by most trophic groups. In a savanna context where faunal diversity is high and no single species is a target for mitigation, a range of underpass designs including larger viaducts, located in different types of vegetation cover, thereby combining the range of requirements of different guilds, is recommended.
Evaluating the Effectiveness of Green Drop Audit Criterion in Relation to Its Link to Enforcement Protocol in South Africa
(University of the Witwatersrand, Johannesburg, 2022-08) Tshongweni, Olwethu Lenox; Tutu, Hlanganani; Richards, Heidi L.
The Green and Blue Drop programs are incentive-based regulatory systems based on the Department of Water and Sanitation's (DWS) realization that rewarding positive behaviour is more efficient and effective than penalizing undesirable behaviour. The Green Drop was developed for the Wastewater Quality Management Regulation certification program. In contrast, the Blue Drop was developed for the certification program for the Drinking Water Quality Management Regulation (Burgess, 2021). Most municipalities have accepted them and have raised awareness about the need for better efficiency in the wastewater sector. The Sand River, in Polokwane wastewater treatment works (WWTWs), was chosen as the research area for this study. This particular river was selected based on the premise of continuous non-compliance of the wastewater treatment plant and the resulting pressure it puts on the Sand River by compromising its quality, with the DWS not having a successful way of regulating and enforcing the water user to abide by the rules of the license that has been issued. This study aims to evaluate the effectiveness of the Green Drop Program audits and assessments about their link to the regulatory system within the DWS. Additionally, a risk assessment and cumulative risk rating are used to assess wastewater discharge into the Sand River in the Limpopo Province. Based on the observation made during the study, it appears that within the DWS organizational arrangements, the lack of coordination among the sectors (compliance monitoring, water quality management, the green drop program, and enforcement), lack of accountability, and the regulatory requirement of cooperation within DWS sectors have hindered implementation. Some of the non-compliance factors may be due to the misuse of funds meant for infrastructure development and difficulties relating to capacity, procurement, and management of the WWTWs. Moreover, DWS's absence of interactive data management systems and business processes contributes to non-compliance. The Polokwane WWTW, directly linked to the Sand River, is overloaded and needs to comply with the Water Use Licence (WUL) conditions. For example, the 21 August 2022, this facility was found to be non-compliant by 69.01%, collectively with administration and technical conditions of the WUL issued to the facility (DWS, 2022c). In addition, this investigation discovered that the Polokwane facility, which has been operating outside of regulations for the past four years, therefore, as calculated in equation 7 could be responsible for 72.3% of the hazards to people's health, the quality of the river's water, and the aquatic ecosystem life in the Sand River in a single month. As much as some municipalities do not perform according to the desired standards, there have been a few noticeable, well-performing ones reported in the green drop report released in 2022. These include Langebaan WWTW (90%), Riebeek Valley WWTW (97%), Gansevallei WWTW (84%), and Wellington WWTW (95%), and this illustrates that the Green Drop Certification is achievable if the municipalities follow and adhere to the Water Use Authorization (WUA) issued them (DWS, 2022b). The DWS must integrate the internal structures or link sectors responsible for monitoring and regulating municipal water service facilities and incentivize performing facilities to improve their performance. Additionally, facilities with minor compliance issues, such as water quality, must be referred to the Water Quality Management (WQM) unit for further investigation and recommendations. However, those non-compliances of authorized wastewater treatment facilities that require regulatory attention must be referred to the compliance monitoring sector through the system for compliance monitoring. Lastly, those facilities that are not authorized must be directed to enforcement for further action. Therefore, using the Integrated Regulatory Information System (IRIS) as the umbrella body for both database and work-based information has an imperative role that can curb some of the issues faced by the DWS. Standard operating procedures (SOPs) should guide all interactions between these systems.
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, Elena
Data 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.
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.

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