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Deep neural networks for robot vision in evolutionary robotics

  • Authors: Watt,Nathan
  • Date: 2021-04
  • Subjects: Evolutionary robotics -- South Africa , Neural networks
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/61601 , vital:71473
  • Description: Description Advances in electronics manufacturing have made robots and their sensors cheaper and more accessible. Robots can have a variety of sensors, such as touch sensors, distance sensors and cameras. A robot’s controller is the software which interprets its sensors and determines how the robot will behave. The difficulty in programming robot controllers increases with complex robots and complicated tasks, forming a barrier to deploying robots for real-world applications. Robot controllers can be automatically created with Evolutionary Robotics (ER). ER makes use of an Evolutionary Algorithm (EA) to evolve controllers to complete a particular task. Instead of manually programming controllers, an EA can evolve controllers when provided with the robot’s task. ER has been used to evolve controllers for many different kinds of robots with a variety of sensors, however the use of robots with on-board camera sensors has been limited. The nature of EAs makes evolving a controller for a camera-equipped robot particularly difficult. There are two main challenges which complicate the evolution of vision-based controllers. First, every image from a camera contains a large amount of information, and a controller needs many parameters to receive that information, however it is difficult to evolve controllers with such a large number of parameters using EAs. Second, during the process of evolution, it is necessary to evaluate the fitness of many candidate controllers. This is typically done in simulation, however creating a simulator for a camera sensor is a tedious and timeconsuming task, as building a photo-realistic simulated environment requires handcrafted 3-dimensional models, textures and lighting. Two techniques have been used in previous experiments to overcome the challenges associated with evolving vision-based controllers. Either the controller was provided with extremely low-resolution images, or a task-specific algorithm was used to preprocess the images, only providing the necessary information to the controller. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-04

Descriptive analysis of organic farming systems and factors affecting adoption and disadoption in Zambia : a case study

  • Authors: Munthali, Robert
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic farming -- Zambia
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52111 , vital:43434
  • Description: The last 30 years since the early 1990s has seen the heightened promotion of organic farming as a sustainable farming option in Zambia. The main objectives of this research study were to carry out an analysis of organic farming systems in order to understand factors affecting adoption, as well as reasons why some organic farmers discontinue using the approach. The study involved four districts in Zambia: Mazabuka, Chikankata, Lusaka and Chongwe. Specifically, the research investigated challenges and limitations of organic agronomic practices, and analysed factors that influence adopters and disadopters of organic agriculture. Primary data were collected through interviews and by administering semi-structured questionnaires. The research population comprised approximately 250 farmers adopters and disadopters, with the sample size being 50 farmers chosen across four districts using systematic random sampling methods. Additionally, five observation research field trials were conducted in order to gather practical data on individual farmer’s crop management practices. Farmers adopting and maintaining organic methods reported several reasons for embracing the system, some of which are: organic farming is regenerative; it is environmentally responsible; it uses manure, believed to help build healthy soils rich in organic matter with better nutrient and moisture holding capacity; pesticides and synthetic fertilizers are not used, reducing the levels of toxic residues in organic products which ultimately promotes health. Labour constraints, pest and disease challenges and weed problems were some of the reasons for disadoption. Data showed that disadopters had lower education (48% had primary education), were older and with slightly more children. Although there were more women adopting organic agriculture compared to men, the difference was small 56% and 44% women and men respectively. Among disadopters there were more women (67%) compared to men (33%). Overall, the study results suggest that promotion of organic agriculture should be encouraged through liaison with government departments such as the Zambian Department of Agriculture to include organic agriculture when developing policies. In general, organic farmers have positive opinions concerning the benefits resulting from organic agriculture. Organic farmers should enjoy equal opportunities to conventional agriculture in the provision of extension services, input support, infrastructural development, access to financial resources to procure farm machinery, and equipment and most important of all, they should get fair prices for their organic produce and products. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Estimating activity patterns in camera trap studies, and the overlap between domestic and indigenous ungulates

  • Authors: Peral, Christopher Michael
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ungulates -- Behavior -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52019 , vital:43437
  • Description: Animal activity can reveal responses to social and ecological factors such as the presence of food, water, shelter, predators, competitors or conspecifics. Thus, an understanding of an animal’s activity patterns provides insights into how and why they are using landscapes in the manner in which they do. Camera trap surveys, typically used to record the occurrence of species of interest, are also an efficient way to collect data regarding animal activity patterns but require robust analytical methods. The analysis of camera trap data requires assumptions that may differ for camera trap surveys that estimate occurrence or activity. One such assumption is temporal independence. This refers to the removal of images within a specified time interval, as these images are assumed to be images of the same individual. This assumption stems from the use of-time-to-independence in occurrence or density-based studies, where it reduces overestimation of animal counts. In studies of animal activity, this assumption is generally used, even though animal behaviour or activity occurs continuously over time and as such should be measured over time. I analysed 112 467 images of eight cooccurring species, to test the effect across various times to independence, these being set at 1, 5, 10, 15, 30 and 60 minutes. Time-to-independence resulted in significant loss of data and biased the interpretation of the activity patterns of species and interactions amongst species, particularly for herbivorous social species. In light of these findings, activity pattern estimates based on camera trap studies should be cautious when using time-to-independence. I then explore ‘habitat use’ in space and time by domestic and indigenous ungulates using a camera trap survey. Domestic ungulates (livestock) have become common place on rangelands and may compete with native species. It was hypothesised that there will be overlap in habitat use by livestock and indigenous ungulates. My results show that indigenous ungulate species, particularly larger species such as kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis), changed their spatial and temporal use as a result of the presence of domestic ungulates. Other smaller indigenous ungulates, such as steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), were less affected by the presence of livestock. Kudu were found to use more open habitats at different times whilst springbok used more dense habitats at different times in the presence of livestock. This supports the hypothesis of competition between livestock and indigenous ungulates. This study provides novel insight into the analysis and interpretation of activity patterns based on camera trap surveys. Additionally, this study demonstrates the competitive displacement between domestic and indigenous ungulate species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Estimating Bayesian tolerance intervals for a two - factor factorial model

  • Authors: Besele, Kagiso Francis
  • Date: 2021-04
  • Subjects: Gqenerha (South Africa) , Eastern Cape (South Africa) , Mathematical statistics
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52302 , vital:43587
  • Description: Quality improvement efforts have become the cornerstone of all manufacturing processes. Quality can be defined in terms of variability reduction, and since variability is a statistical concept, statistical techniques such as statistical quality control present techniques for assessing process variation. Methods such as experimental design provide a way to ascertain factor relationships and give a basis for computing variability that arises from each process variable, ultimately providing a way of calculating total process variability. This in turn results in variance components and eventually variance component estimation. As with any statistical model, estimates may be classified in any one of two ways, point estimates or interval estimates. Interval estimates that provide information about an entire population, and not only information on a few observations from a sample or knowledge about only a population parameter, are known as tolerance intervals. Wolfinger (1998) provided a Bayesian simulationbased approach for ascertaining three types of tolerance intervals using a balanced one-way random effects model. In this study, the method initially proposed by Wolfinger (1998), is extended in order to estimate tolerance intervals for the balanced two-way crossed classification random effects model with interaction. The suggested and derived techniques will be applied to the thermal impedance data initially collected by Houf and Berman (1988), and the method presented by Wolfinger (1998) will be expanded to also include the estimation of tolerance intervals for averages of observations from new or unknown measurements. This Bayesian approach provides a thorough but yet simplistic paradigm to using tolerance intervals in manufacturing settings. , Thesis (MSc) -- Faculty of Science, Statistics, 2021
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  • Date Issued: 2021-04

Estimating the population size of three large carnivore species and the diet of six large carnivore species, in Madikwe Game Reserve

  • Authors: Honiball, Terry-Lee
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Carnivores
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52139 , vital:43421
  • Description: Large carnivores play a vital role in ecosystems, providing ecosystem services such as herbivore regulation. If not properly monitored, carnivores could place significant pressure on certain prey species, and in extreme cases, result in the local extinction of certain species. A lack of demographic data can indirectly threaten carnivores, as policies and management decisions based on demographic data can result in the over harvesting or unsustainable hunting of large carnivores. Furthermore, their conservation is becoming confined to small, fenced, protected areas. Whereby species are intensively managed, making demographic and ecological data a fundamental part of conservation decisions. Therefore, it is essential for conservation practitioners to understand large carnivore demography and their role, to conserve them effectively. To provide Madikwe Game Reserve with the necessary data for effective long-term monitoring and management of the large carnivore guild, I estimated the population size of the cryptic carnivores. I then investigated the efficacy of different camera trap survey designs on improving the detection probability of leopard (Panthera pardus), brown hyaena (Parahyaena brunnea), and spotted hyaena (Crocuta crocuta). I found that brown hyaena and spotted hyaena detection probability increased with a higher number of camera traps, whereas leopard detection probability did not increase with an increased number of camera traps. I further investigated the diet, prey preferences and dietary overlap of lion (Panthera leo), cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus), leopard, spotted hyaena and brown hyaena. I found that all species displayed a degree of dietary overlap, however the most notable level of competition occurred between leopards, wild dogs, and cheetahs. This iv information will assist MGR to make informed decisions about large carnivore management in the reserve. I recommend continued long-term monitoring for the establishment of trends over time, allowing for holistic management of the entire large carnivore guild. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-04

Evolutionary robotics controllers with location perception facilitated by neural network-based simulators

  • Authors: Phillips, Antin Paul
  • Date: 2021-04
  • Subjects: Evolutionary Robots -- South Africa , Neural networks (Computer science) -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/61613 , vital:71474
  • Description: Humans impressively maintain a real-time approximation of their bodily form. For instance, one knows where one’s arm is, relative to the body, without needing to directly observe it. This ability, in part, allows humans to interact with the environment without direct observation. This bodily sense is referred to as ”proprioception“. The human body contains various proprioceptors, sensory neurons which provide information about the physical state of the body. This information, along with internal body representations that humans develop over time, allows one to maintain an approximation of their bodily form. Humans also possess an impressive sense of direction and navigation ability. For instance, a blindfolded human can move around a familiar environment and maintain an approximate sense of where they are within that environment. This ability is, in part, enabled by proprioception as it provides one with an approximation of the effects their actions have on their body. The field of Evolutionary Robots (ER) makes extensive use of robotic simulators to carry out simulated robotic evaluations. Research has been conducted into alternate forms of simulation and Simulator Neural Networks (SNNs) were subsequently developed. The speed and accuracy of these SNNs, relative to more typical simulation techniques, is what inspired the approach explored in this research. Robots do not necessarily possess the appropriate hardware to sense their position within an environment. Thus, it was proposed that SNNs could be incorporated into ER controllers to approximate the position of the robot. These SNNs would be executed in parallel to the robot and provide a constant approximation of the robot’s position. This would provide controllers with information that they would not otherwise have, albeit approximate information. Various experiments were carried out which examined both typical ER controllers as well as those which were augmented in the proposed fashion. The augmented controllers were found to outperform typical controllers as well as develop more advanced and efficient behaviours. Furthermore, the augmented controllers demonstrated the ability to solve tasks that regular controllers could not. A potential criticism of the approach suggested in this research is that ER controllers could hypothetically be trained in such a way that the proposed augmentation would be unnecessary. This possibility was investigated and it was found that successfully training controllers in such a manner would be unlikely. Furthermore, the effort involved in fine-tuning this training process would be greater than simply following the approach suggested in this research. Another potential drawback of the suggested approach involved the accuracy of the information that SNNs could provide to controllers. The approximated information was found to diverge over time and negatively affected controller performance. A method to address this issue was proposed and subsequently implemented. This method was demonstrated to be an effective means of reducing the divergence of the SNNs outputs and, in turn, improved controller performance. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-04

Evolutionary robotics controllers with location perception facilitated by neural network-based simulators

  • Authors: Phillips, Antin Paul
  • Date: 2021-04
  • Subjects: Grahamstown (South Africa) , Eastern Cape (South Africa) , Neural networks (Computer science) -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52137 , vital:43444
  • Description: Humans impressively maintain a real-time approximation of their bodily form. For instance, one knows where one’s arm is, relative to the body, without needing to directly observe it. This ability, in part, allows humans to interact with the environment without direct observation. This bodily sense is referred to as ”proprioception“. The human body contains various proprioceptors, sensory neurons which provide information about the physical state of the body. This information, along with internal body representations that humans develop over time, allows one to maintain an approximation of their bodily form. Humans also possess an impressive sense of direction and navigation ability. For instance, a blindfolded human can move around a familiar environment and maintain an approximate sense of where they are within that environment. This ability is, in part, enabled by proprioception as it provides one with an approximation of the effects their actions have on their body. The field of Evolutionary Robots (ER) makes extensive use of robotic simulators to carry out simulated robotic evaluations. Research has been conducted into alternate forms of simulation and Simulator Neural Networks (SNNs) were subsequently developed. The speed and accuracy of these SNNs, relative to more typical simulation techniques, is what inspired the approach explored in this research. Robots do not necessarily possess the appropriate hardware to sense their position within an environment. Thus, it was proposed that SNNs could be incorporated into ER controllers to approximate the position of the robot. These SNNs would be executed in parallel to the robot and provide a constant approximation of the robot’s position. This would provide controllers with information that they would not otherwise have, albeit approximate information. Various experiments were carried out which examined both typical ER controllers as well as those which were augmented in the proposed fashion. The augmented controllers were found to outperform typical controllers as well as develop more advanced and efficient behaviours. Furthermore, the augmented controllers demonstrated the ability to solve tasks that regular controllers could not. A potential criticism of the approach suggested in this research is that ER controllers could hypothetically be trained in such a way that the proposed augmentation would be unnecessary. This possibility was investigated and it was found that successfully training controllers in such a manner would be unlikely. Furthermore, the effort involved in fine-tuning this training process would be greater than simply following the approach suggested in this research. Another potential drawback of the suggested approach involved the accuracy of the information that SNNs could provide to controllers. The approximated information was found to diverge over time and negatively affected controller performance. A method to address this issue was proposed and subsequently implemented. This method was demonstrated to be an effective means of reducing the divergence of the SNNs outputs and, in turn, improved controller performance. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-04

Factors affecting the performance of the wooden furniture manufacturing industry in the Southern Cape

  • Authors: Vheriwa, Prayer
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Furniture making -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52017 , vital:43449
  • Description: The furniture manufacturing industry in South Africa is facing several challenges that affect the performance of firms in this sector. A literature review indicates several factors such as availability of resources; location; access to local markets; access to export markets; and development programmes that may affect the performance of wooden furniture manufacturing firms in the Southern Cape. The purpose of the current study was to fill the knowledge gap on why the performance of wooden furniture manufacturing firms in the Southern Cape has declined. The study intends to contribute to the limited formal information resources on the Southern Cape furniture manufacturing industry. A conceptual framework was developed and employed for investigating factors hypothesised to affect the performance of furniture manufacturing firms in the Southern Cape. The research conducted was explorative. An interpretive paradigm was selected to collect and interpret qualitative data and a positivist paradigm was used for the quantitative component of the study. The quantitative data was subjected to a chi-square test using IBM SPSS statistics software and qualitative data was analysed for meanings and context using ATLAS.ti software. Statistical tests on qualitative and quantitative data were conducted to determine whether sufficient evidence existed to make conclusions on the hypotheses, relating to significant relationships between the selected independent variables for the study and the performance of wooden furniture manufacturing firms in the Southern Cape. The results show that existing development programmes and availability of resources, namely: timber, skilled human resources and availability of finance, influence the performance of furniture manufacturing firms in the Southern Cape. Results further reveal that location; access to local market; and access to export market have a partial influence on the performance of the furniture manufacturing firms in the Southern Cape. The study presents information which serves to improve the capacity for growth of wooden furniture manufacturing firms. Based on the results, recommendations were made to overcome the factors affecting the performance of the furniture manufacturing firms in the Southern Cape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-04

Fish ecology and ecophysiology in an anthropogenically-altered temporarily open/closed estuary in the warm-temperate region of the Eastern Cape Province, South Africa

  • Authors: Mpinga, Mfundo
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fishes--Ecology--South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52122 , vital:43431
  • Description: Estuaries are globally recognized for their contribution to the coastal marine environment by acting as nursery grounds for numerous marine estuarine-dependent fish species. These linking ecosystems between marine and riverine environments, are ideal for these species due to the habitat diversity, nutrient and food availability, shallower and calmer environments they provide relative to the ocean. Abrupt hydrodynamic and physico-chemical changes which frequently occur in estuaries impose physiological stress and requires superior adaptability in the fish that reside within them. This is exacerbated by anthropogenic modifications to estuaries which affects their natural ecological function. The Seekoei Estuary is one of 192 temporarily open/closed estuaries (TOCEs) in South Africa and these estuaries are characterised by their periodical connection to the sea due to the formation of a mouth berm. These estuaries are the dominant type in South Africa. A lot of research has been done in these kinds of estuaries, however, it is still limited due to their vast numbers. These estuaries are popular for human settlement and this has led to mismanagement due to the lack of ecological information. Furthermore, because of their inability to continuously flush out water, temporarily open closed estuaries are more vulnerable to pollution and anthropogenic modifications. The aim of this study was to assess the small fish community in relation to their environment in the hypersaline anthropogenically-altered Seekoei Estuary, by analysing the spatio-temporal trends of physico-chemical properties, nutrient loads, phytoplankton biomass and fish community structure. In addition, histological adaptation in gills of fish that survive hypersaline water was investigated. The study found that physico-chemical properties were influenced by anthropogenic alterations, in particular adverse water abstraction, instream water obstructions and artificial breaching. Nutrient concentration was found to be influenced by the intense agricultural practices in the upper reaches. It was evident that nutrient concentration (dissolved inorganic phosphorus) coupled with high salinity and optimum temperature (15 oC - 20 oC) affected the phytoplankton biomass. This estuary’s inability to naturally breach makes it vulnerable to phytoplankton blooms. The accumulation of cohesive silt caused by low river inflow, due to water abstraction in the upper reaches, was attributed to this estuary’s prolonged mouth closure. This was exacerbated by the presence of the causeway, which acts as a barrier between the middle and lower estuary. The abundance of marine fish species in the estuary, despite its long closure, indicates that the larvae and juveniles of these species make use of overwash events and brief artificial breaching events to recruit into the estuary. The high species richness in iii sites below the causeway is indicative of the barrier effect, which prevents the migration of some species to the upper reaches. This was evident during a massive fish kill, recorded during this study, which was more severe in sites below the causeway than above it. Chloride cell hyperplasia, mucus secretion and thickening of the epithelial layer in gills of indicator fish species from this estuary was the histological adaptation, which enables these fishes to be tolerant to high salinity. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Flash floods prediction in South African urban areas: Jukskei river catchment as case study

  • Authors: Mawasha, Tshepo Sylvester
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52059 , vital:43429
  • Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Fragmentation of the Albany Thicket Biome: consequences for the biodiversity and health of thicket vegetation

  • Authors: Carvalho, Shandon Luke
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fragmented landscapes
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52344 , vital:43599
  • Description: The dense impenetrable vegetation of the Albany Thicket Biome is highly resistant to a wide variety of disturbances but, once disturbed, lacks the regenerative qualities that allow it to return to a stable state. Agricultural development is the main cause of degradation in this biome, creating a landscape consisting of patches of thicket vegetation scattered throughout land cleared for crops or transformed through grazing by domestic livestock. The main objective of this study is to determine the health, status and biodiversity of thicket fragments as it relates to elephant impacts. The level of fragmentation and the remaining extent of intact thicket were investigated as its current status is unknown. The findings suggest that the Thicket Biome is highly fragmented as almost 50% of solid thicket has been cleared, transformed or degraded by agricultural or urban development. For Arid Thicket, the level of fragmentation and the remaining extent of intact thicket could not be determined and both could potentially be greater. For the intact thicket of Dune, Mesic and Valley Thicket types, patch sizes ranged between almost 6 and 876 km2 while the weighted mean was between 2 and 251 km2 . Remote sensing methods (NDVI) were used to determine whether the health of thicket could be remotely assessed. The thicket within and beyond the extent of piospheres around watering holes is subjected to different levels of herbivory. These different levels were compared to corresponding NDVI values with the latter accurately measuring the impact of herbivores along a gradient and providing a method to assess the health of thicket vegetation. Ground surveys of the edge effect, along thicket fragments adjacent to open pastures and separated by cut lines, were conducted. Based on these surveys, the extent of the edge effect was established at a distance of 7 m into thicket fragments separated by cut lines but could not be determined for thicket fragments adjacent to open pastures. Ground surveys were also conducted to assess the health of thicket vegetation exposed to different levels of herbivory, including the impact of elephants (Loxodonta africana). Results showed that different elephant densities produced different levels of impact that could be described in terms of changes in species richness, species diversity, plant height and cover, and growth form composition. Lastly, the findings of the health-based assessments were combined with elephant densities to develop a model that could assess the health of thicket vegetation using a range of ecological variables and relate it to an ideal range of elephant densities. This assessment method was tested at the Addo Elephant National Park and results showed that an elephant density of 1 elephant/km2 would maintain the appropriate diversity, structure and composition of thicket. , Thesis (MSc) -- Faculty of Science, Department of Botany, 2021
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  • Date Issued: 2021-04

Impact of feeding milk once-a-day on growth and development of jersey calves

  • Authors: Myburgh, Albertus Petrus
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Calves -- Feeding and feeds
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52095 , vital:43438
  • Description: In conventional calf rearing systems calves are fed milk twice a day. Calves are normally housed in a calf shed, kept in individual pens or in groups. The goal should be to limit mor-talities to less than 5% from birth to 30 days. This can be achieved by reducing animal stress, controlling diseases and feeding the animals properly. The immune function can be de-pressed by inadequate nutrition which will increase susceptibility to diseases. Key objective on a dairy farm should be to rear a healthy calf until the calf reaches the optimum mating weight. Digestive disorders and respiratory diseases are the main causes of mortalities of young calves. Jersey calves at Outeniqua Research Farm are kept in movable hutches out-side, for 8 weeks and whole milk is fed only once a day. Although it is common practice to feed milk to calves twice-a-day, Jersey calves are raised with great success by feeding whole milk once-a-day, but proven data was never collected to indicate that feeding whole milk to Jersey calves does not compromise growth or development of calves. Much research was done on feeding of milk to Holstein calves, but little was done on Jersey calves. Research also shows results on feeding of milk replacer rather than whole milk. This raised the question of can whole milk be fed once-a-day successfully to Jersey calves with-out compromising growth and development and what are the advantages of feeding whole milk once-a-day to Jersey calves? , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Incidence of parasitic trematodes effects on the energetics and behaviour of Coryogalops sordidus (Family: Gobiidae) resident in microbialite pools, warm temperate South Africa

  • Authors: Du Toit, Hendrik Daniël
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Gobiidae -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52458 , vital:43666
  • Description: Coryogalops sordidus(Epaulette goby), is a cryptobenthic species of the Family Gobiidae that iscommonly foundoccupying turbulent surf zones, calm rock pools, and sand and mud flats, where they are generally carnivorous predators. The distribution of C. sordidushas been recorded for Kenya, Tanzania, Mozambique, and South Africa. The species is also resident in the microbialite pools on the temperate south east coast of South Africa. Recent reports indicated these gobies to be covered in numerous dark lesions, possibly suggesting that the microbialite pools are a sub-optimal habitat. Preliminary analyses have indicated that the dark lesions are a result of encysted metacercaria of a digenetic trematode (fluke). There werehowever,no current recorded parasiticspecies occurring within microbialite pool nor any records of any parasitic species utilizingC. sordidus as a host in South Africa. Therefore, the aim of this study was to investigate parasite-host interactions and parasite presence in and around themicrobialite pool systems of Algoa Bay using C. sordidusas a study species. Coryogalops sordiduswas identified to be parasitised by digenetic trematode metacercaria of the Family Diplostomidae Poirier, 1886, localised primarily to the host musculature, fins, eyes, and integument with no settlement on any of the visceral organs. Furthermore, C. sordidus was found additionally parasitised by a green leech (Class: Hirundinea) of the Family Piscicolidae Johnston, 1865, localised exclusively to the ventral body surface, underneath the pelvic fin of the host. Further investigation into the life cycle of the trematode, suggested that the most probable final hosts wereherons,namely Ardea cinereaand Egretta garzetta garzetta, and intermediate host likely being the freshwater gastropod Assimineacf.capensis, present inthe upper microbialite pools. In both the microbialite and neighbouring rock pools trematode prevalence was found to oscillate in response to seasonal chemical and climatic conditions, whereas the secondary piscicolid leech parasite was influencedmoreby host presence than environmental conditions. Greater prevalence and intensity were measured in the microbialite pools suggesting that these systems likely contained a suit of favourable conditions that allowed for greater trematode loads to be maintained as compared to neighbouring rock pools. As parasites often have deleterious effects on their hosts, the response can manifest as an altered host behaviour or an increased energetic debt due to elevated immune response activity and the associated cost of tissue repair at sites of parasite aggregation.This study further investigatedifgobies (C. sordidus) infected with metacercarial cysts display higher metabolic ratesordifferent swimming behaviour compared to non-infected individuals. The results indicated that the metacercarial load carried by infected hosts had on average no significant impact on energetics, swimming ability, or swimming behaviour, concluding that the average metacercarial intensity present on the gobies is therefore below the threshold of an altered host response. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04

Large mammalian fauna of the Palaeo-Agulhas Plain: predicting habitat use and range distribution

  • Authors: Brooke, Christopher F
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Herbivores
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52332 , vital:43590
  • Description: Understanding the variations in structure and abundance of animals and what leads to their distribution within the landscape has captured the attention of ecologists for centuries. Importantly, knowledge of current behaviour of large mammals can be used to inform historic population dynamics and is essential to understanding how early humans used large mammals as a foraging resource. Central to this thesis and improving our understanding of large herbivores is the Palaeo-Agulhas Plain (PAP) where large mammalian herbivores formed a key food resource for early humans. The PAP, now submerged off the southern Cape of South Africa, formed a novel ecosystem during lower sea levels. Characterised by large expanses of nutrient rich grasslands and large grazing herbivores, the PAP stands in stark contrast to the nutrient poor fynbos ecosystems that is in the southern Cape today. In this thesis I focus on the Last Glacial Maximum (LGM; ~20 ka) when the PAP was last fully exposed to answer questions relating to the habitat use and range distribution of large herbivores. Importantly, through the Paleoscape Project, modelled climate, soil and vegetation have made these recreations of large mammals possible. Using modelled climate and vegetation this thesis aims to model the large herbivore communities and understand the influence of early humans on the PAP during the LGM for successful integration into the PaleoscapeABM (the PAP agent-based model). To improve our understanding of large mammals on the PAP I identified five large herbivores that became extinct on the PAP since the LGM and modelled their behavioural and physical traits using k-Nearest Neighbour imputation. I predicted the biomass of large herbivores across the PAP using actual biomass of large herbivores from 39 protected areas across South Africa (spanning five functional groups to include the extinct species) across a rainfall gradient and different biomes. The distribution of large herbivores would likely have been driven by similar top-down and bottom-up drivers we see in large herbivore ecology today. Knowing this, I created a predictive model for large mammals by predicting the probability of occurrence of functional groups of large herbivores in relation to environmental drivers and humans. Results showed that all species (except Antidorcas australis) were adapted to the grassy environment of the PAP and these specialisations likely contributed to their extinction along with changing climates and intensified hunting from humans. When predicting herbivore viii biomass, biome was the most important factor influencing the relationship between herbivores and rainfall. In general, large herbivore biomass increased with rainfall across biomes, except for grassland. Finally, I showed the probability of occurrence of large herbivores was influenced by early humans, water availability and a landscape of fear on the PAP. Through this thesis I have successfully provided detailed accounts of the biomass and probability of occurrence of large herbivores on the PAP. Importantly, this information can be seamlessly integrated into the PaleoscapeABM. Finally, I highlight the importance of this knowledge in understanding early humans, the potential shortcomings of this study and resulting areas where research needs to be focused. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-04

Linking agrochemical pollution with the aquatic ecological integrity of the Twee River Catchment, Western Cape

  • Authors: Brink, Zanné
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52326 , vital:43588
  • Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-04

Nurse educators’ understanding of Africanising undergraduate education at a nursing education institution

  • Authors: Mlatsha, Ayanda
  • Date: 2021-04
  • Subjects: Nursing --South Africa , Organizational Change -- Education , Educational change--South Africa --Nursing
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/60764 , vital:67197
  • Description: In the light of transformation and the need for a relatively recently liberated country to enhance higher education, one of the foremost demands of South Africans in education was that of Africanising higher education. Africanising is associated with the term ‘transformation’. The latter is a process that requires the revision of the existing education system towards that of an African-contextualised education system in Africa. Concurrently the nursing profession has an increased need for transcultural nursing in education to ensure that undergraduates deliver culturally aligned and African contextualised nursing care. At present, there is no clear description of how Africanising nursing education can be carried out by nurse educators. Hence some educators argue that the change may not be a smooth process as there is no blueprint that provides guidance for how the process should be conducted. This study intended to assist in describing the meaning of Africanising nursing education as it is understood by nurse educators in a Nursing Education Institution (NEI). Therefore, this study explored and described nurse educators’ understanding of Africanising undergraduate nursing education at a NEI in the Nelson Mandela Bay in the Eastern Cape, South Africa in order to construct recommendations for NEI managers and nurse educators on how the process of Africanising undergraduate nursing education at NEIs can be facilitated. The researcher used a qualitative descriptive approach. The postcolonial theory was used to underpin this study. Purposive sampling was utilised to select nurse educators for participation in the study. Each of the twelve participants were asked to draw a naïve sketch regarding their understanding of fricanisation of the undergraduate nursing education followed by an individual semi-structured interview. Data collection was conducted online, using recorded Zoom sessions. Content analysis was used to aanalyse the data and the findings were used to construct recommendations for NEI managers and nurse educators on how the process of Africanising undergraduate nursing education at NEIs can be enhanced. Throughout the study ethical principles as well as the requirements related to the concepts of trustworthiness, credibility; dependability; confirmability and transferability were upheld. , Thesis (MSc) -- Faculty of Health Sciences, School of Clinical care and Medicinal Sciences, 2021
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  • Date Issued: 2021-04

On the ideals and semimodules of commutative semirings

  • Authors: Olivier, Ruan
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52782 , vital:44026
  • Description: Semirings are a generalisation of rings where additive inverses need not exist. In this dissertation, we focus on results of commutative semirings with non-zero identity. Many results that we study are analogous to results from commutative rings with non-zero identity. Properties which are unique to semirings are also investigated, such as semirings where all elements are additively idempotent. The notion of ideals is examined in the context of a semiring. Specifically, prime ideals, maximal ideals, k-ideals and partitioning ideals of semirings are considered. Additionally, the module over a ring is generalised to a semimodule over a semiring. The emphasis is on prime subsemimodules and multiplication semimodules. Lastly, invertible ideals of semirings are examined. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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  • Date Issued: 2021-04

Optimising the uptake of [𝐈𝐫𝐂𝐥𝟔]𝟐− by a diammonium resin: HCl effect and resin performance

  • Authors: Ngayeka, Mbokazi Zizipho
  • Date: 2021-04
  • Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/54089 , vital:46284
  • Description: The separation of [IrCl6]2- from [RhCl5(H2O)]2- by silica microparticles functionalized with 1,10-diamindecane (C10) and quaternized with 4-nitrobenzylchloride (NO2Benz) in various hydrochloric acid mediums was investigated by continuous column studies. The sorbent materials were synthesized using three different routes: Synthesis route 1 (NaI catalyzed synthesis of diammonium functionalized silica microparticles), Synthesis Route 2 (via silylazation of silica followed by functionalization) and Synthesis Route 3 (silane-based sorbent material). The functionalized sorbent materials were characterized by NMR, Microanalysis, SEM-EDS, FT-IR, TGA and BET surface area. The separation efficiency of the quaternary diammonium cations was investigated under dynamic flow adsorption conditions. Preliminary ICP-OES runs were done, at 6 M HCl, to assess which synthesis route gave the best performing sorbent material. [IrCl6]2- selectivity of the sorbent materials was achieved by washing with an HCl solution to remove unadsorbed metal species, then stripping off the [RhCl5(H2O)]2- with 0.05 M of sodium chlorate and the iridium species was eluted with a 20% HCl solution. From the preliminary ICP-OES, loading capacities were calculated, and it was observed that the three sorbent materials from synthesis route 2 (13.89 mg/g for (4) SSC10NO2Benz-A, 1.44 mg/g for (5) SSC10NO2Benz-HoA, and 1.0859 mg/g for (6) SSC10NO2Benz-DoA) showed the highest uptake of [IrCl6]2- and route 1 (1.89 mg/g for (1) SSC10NO2Benz-A, 1.25 mg/g for (2) SSC10NO2Benz-HoA and 0.99 mg/g for (3) SSC10NO2Benz-DoA ) and Route 3 (0.55 mg/g for (7) SC10-AI and 0.755 mg/g for (8) SC10-ACl) materials did not perform efficiently enough, thus were not used further for the HCl study. Within synthesis route 2, three sorbent materials were evaluated, which had varying quantities of the cation: SSC10NO2Benz-A (having a quantity previously used in our research and denoted A), SSC10NO2Benz-HoA (having a quantity Half of A) and SSC10NO2Benz-DoA (having a quantity double of A). SSC10NO2Benz-A showed the highest loading capacity than SSC10NO2Benz-HoA and SSC10NO2Benz-DoA; HCl studies were carried out using SSC10NO2Benz-A. HCl solution having different concentrations (5, 5.5 , 6 , 6.6 and 6.8 M) were used to prepare the metal solutions. This was done to assess which HCl concentration gave the best metal solution containing high amounts of [IrCl6]2- and [RhCl5(H2O)]2-, which would result in a more efficient separation. An auto titrator was used to standardize the HCl concentrations, and the metal ion chloride species solutions were determined by UV-Vis, and their concentrations were confirmed with ICP-OES. Column sorption of iridium and rhodium on SSC10NO2Benz-A using these HCl solutions was carried out, and loading capacities of [IrCl6]2- were obtained. The loading capacities of the 5 M, 5.5 M, 6 M, 6,6 M and 6.8 M HCl solutions for [IrCl6]2- were 2.64, 4.01, 13.89, 18.15 and 7.23 mg/g, respectively. The optimum separation conditions were thus determined by investigating effective parameters such as the method of synthesis, silica to cation ratio, HCl concentration and flow rate. This thesis presents quaternary diammonium sorbent materials that could be applied in feed solutions from ore processing for iridium recovery. , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
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  • Date Issued: 2021-04

Participatory mapping of cultural ecosystem services in the Mountain Zebra National Park, South Africa

  • Authors: Mpapane, Nelsiwe Pertunia
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Nature--Effect of human beings on--South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52103 , vital:43432
  • Description: Cultural ecosystem services (CES) are an essential part of human well-being. CES characterize the intangible connections that people have with their surrounding environments, and act as vessels to facilitate the understanding of meaningful and respectful relationships between humans and nature, which are necessary for sustainability. However, CES render themselves as complex cultural dimensions that are difficult to connect to specific aspects of an ecosystem, or to measure and manage. Thus, a progressive approach is required for promoting effective management of CES within landscapes. This thesis endeavours to understand human─nature interactions in protected areas, the CES benefits that arise from such interactions, and the links of these to ecosystems, facilities or features within the landscape. Protected areas represent some of the last remaining intact ecological areas that support biodiversity conservation and human─nature experiences. Protected areas, such as the Mountain Zebra National Park, are therefore suitable study sites to cast light on: (a) how human─nature relationships manifest in parks, (b) which CES are experienced by visitors, (c) which landscape features are associated with CES benefits, (d) who visits the Park, and (e) how the delivery and/or accessibility of CES to visitors of the Park could be improved. My research involved qualitative and spatial elements as forms of enquiry over a period of six months of data collection. I used semi-structured interviews (n = 20) paired with a participatory mapping approach. Additionally, I performed a comparative analysis using a peer-reviewed paper that focused on the management perspectives of CES delivery, to seek out similarities and differences between management perspectives and actual visitor experiences. The findings of this study have outlined that the Mountain Zebra National Park offers significant benefits to visitors. Aesthetic, recreational, inspirational value and cultural heritage emerged as the most frequently mapped CES. The findings have also shown that CES benefits are widely distributed across the landscape, with a spatial correlation in hotspot areas. Moreover, amenities or built infrastructure such as picnic iii sites, camping areas and viewpoints within the Park, are crucial for strengthening social relationships among family and friends, as well as in aiding the delivery of CES. This study provides insights into the subjective and diverse ways that human─nature relationships translate into CES benefits. It also sheds light on the importance of adequate planning within protected areas, for the maximization of the benefits from CES to people without compromising the mandate of biodiversity conservation. This study also contributes to a growing body of evidence that documents human─nature interactions in, and non-material benefits acquired from, protected areas within South Africa. I further advocate for improved access, adequate infrastructure, awareness creation and strategies to attract the younger generation to the national parks of South Africa. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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  • Date Issued: 2021-04

Recreating a wetland at an abandoned saltworks : towards a rehabilitation plan

  • Authors: Wasserman, Johan
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52146 , vital:43450
  • Description: A saltworks at Swartkops Estuary was abandoned in 2018. While operational, the saltworks hosted some of the largest breeding colonies of several shorebird species in southern Africa and hosted thousands of Palearctic migrant waterbirds annually. The abandonment of the saltworks has resulted in the loss of the artificially managed hydrological regime and therefore the wetland function and habitat value of the site, and the rich and diverse avifauna that once occurred at the site have not returned. The rehabilitation of the saltworks as a wetland that functions as a waterbird sanctuary is currently being organised, and this research aimed to create a plan for implementing and monitoring the rehabilitation. In order to do so, the baseline environmental condition of the abandoned saltworks was established, the possible rehabilitation interventions necessary for rehabilitating the site were assessed, and the potential ecological implications of any interventions were investigated. The assessment of the saltworks’ baseline condition revealed that the site is now characterised by vast expanses of dry hypersaline sediment with sparse patches of monospecific vegetation and depauperate avifauna. The once rich and diverse waterbird communities have all but disappeared since the site was abandoned and are unlikely to return unless a managed hydrological regime is reinstated. Furthermore, it is improbable that salt marsh vegetation will cover the abandoned saltworks primarily due to the high sediment salinity that will persist unless the saltpans are flooded. The area will likely remain barren with little ecological value if no rehabilitation action is taken. Two potential rehabilitation options for reinstating a hydrological regime at the saltworks were identified: (1) pumping estuary water into all of the saltpans; or (2) pumping estuary water into some of the saltpans, while allowing the largest one to be filled with stormwater. Both options were deemed to be feasible; however, the second option will likely have lower running costs. The use of stormwater to fill the one saltpan is expected to result in brackish conditions initially, while the saltpans filled with estuary water would have salinity levels ranging from euhaline to slightly hypersaline. Both the stormwater and estuary water are rich in inorganic nutrients – the estuary water is rich in both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), while the stormwater has an exceptionally high DIN content. This raised concerns of creating eutrophic wetlands with detrimental conditions such as algal blooms and a hypoxic water column. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
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  • Date Issued: 2021-04
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