4. Electronic Theses and Dissertations (ETDs) - Faculties submissions

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    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.
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    The extent of biodiversity and species reporting by the top 75 companies listed on the london stock exchange (ISE)
    (University of the Witwatersrand, Johannesburg, 2023) Lai, Timothy; Ecim, Dusan; Maroun, Warren
    Corporate activities have significantly contributed to the accelerating decline of biological diversity on a global scale, having contributed to resource exploitation, industrialisation, land-use changes and deforestation in their associated operations. In recent years, the loss of habitats, ecosystems and threatened species has been brought to the attention of the public, mostly as a result of adverse events caused by these organisations in the conduct of their operations. The real impacts and consequences of biodiversity loss, has however, largely remained under-reported resulting in the need for organisations to adopt greater levels of corporate accountability and transparency within their biodiversity reports. This study analyses the primary reports (i.e., annual reports) of the top 75 companies listed on the London Stock Exchange (LSE) across a three-year period (2018 – 2020). These reports are studied in order to assess the quality and quantity of the biodiversity and species extinction disclosures, with thepurpose of identifying any trends and patterns across the three years. This research also assesses the possible determinants driving biodiversity disclosures. A mixed method approach is utilised. The content in the primary reports is analysed and evaluated to identify biodiversity-related disclosures and categorises them according to the themes outlined in a detailed disclosure checklist developed using the existing professional and academic literature. Secondly, the quantum and quality of the biodiversity and species extinction related disclosures included in these reports will be determined using a standardised scoring system. This paper finds that the biodiversity and species extinction disclosure among the LSE-listed companies has remained low in both quality and quantity. Although there is considerable improvement in the biodiversity disclosures year-on-year, the disclosures remain limited in substance, lacking sufficient detail over the biodiversity-related matters conveyed to key stakeholders. This research provides insight into the environmental reporting practices of UK-listed companies and aims to identify the trends, patterns and weaknesses found within biodiversity reporting. This study expands on the limited volume of literature within the environmental accounting field, to ultimately aid the transformation in corporate reporting practices
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    An exploratory study of biodiversity, ecological and extinction reporting among JSE-listed entities
    (University of the Witwatersrand, Johannesburg, 2021) Da Mata, Dino Marco; Maroun, Warren
    The purpose of this research is to explore the level of biodiversity, ecological and extinction reporting among 50 Top JSE-listed entities and the possible determinants of biodiversity, ecological and extinction reporting. This is important because unprecedented biodiversity loss is a major ecological and business risk affecting South African organisations. The thesis is grounded in an interpretive approach to collecting and analysing data and employs a mixed- methods approach. Qualitative content and thematic analysis were used to evaluate what content companies disclose in their integrated reports and to gauge the level of biodiversity, ecological and extinction reporting over the 2018 to 2020 reports. This was followed by the use of quantitative methods to test for associations between identified determinants and the level of reporting. The findings show that, overall, the level of disclosures have increased since 2018. Unfortunately, most of the disclosures are still vague, generic or focus on positive information. The findings also showed that there is a significant relationship between the typeof industry and the level of biodiversity, ecological and extinction reporting. Interestingly, the study found that secondary listed JSE companies have a much higher level of biodiversity, ecological and extinction reporting. The research found that there is a significant relationship between the level of reporting and if the company has a biodiversity partnership or has disclosed the importance of biodiversity. Suggesting that companies are beginning to understand the need to protect biodiversity and prevent further biodiversity loss. This change in mindset is, unfortunately, occurring at a slow pace and more needs to be done by companies, stakeholders and society in general. This thesis is the first study to explore biodiversity, ecology and extinction elements concurrently. It is also the first South African study to explore biodiversity, ecological and extinction reporting across a range of industries