The development of a larval feeding regimen for dusky kob, Argyrosomus japonicus, with a specific focus on the effect of weaning period on larval development and survival
- Authors: Keet, Thomas
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/96897 , vital:31344
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
- Authors: Keet, Thomas
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/96897 , vital:31344
- Description: One of the biggest limiting factors in marine finfish aquaculture is the low survival rate of early-stage larvae. Most mortalities can be ascribed to the poor nutritional value of live feeds, sibling cannibalism, and various stressors that result in swim bladder hyperinflation and/or starvation during the larval stage. Research results vary on the best timing for the introduction of artificial feed for good survival and growth rate in dusky kob larvae. The main objective of this experiment was to improve survival and growth rate. The experiment focused on a new feeding regime that sought to wean larvae onto an artificial diet earlier than the current Argyrosomus japonicus standard (weaning commenced at 16 days after hatch (DAH) versus 20 days after hatch), based on findings and recommendations made by Musson & Kaiser (2014). Three trials were conducted, each with five replicates of the two treatments, namely the new feeding regime and the standard feeding regime in a fully randomised design. Samples from each tank were collected every two days for the duration of the trial. Morphometric measurements (standard length; body depth; eye diameter) obtained from these sample larvae were used to compare growth rates between treatments. The ratio of BD:SL was used to assess larval condition throughout each trial. Tank survival rates were calculated on the last day of each trial.The study indicated that in mean water temperatures ranging from 24.3 – 25.2 °C, dusky kob larvae can be weaned onto an artificial pellet diet from 16 - 21 DAH without any negative effects on growth, condition and survival. Results from the highest mean temperatures of Trial 2 show a better mean condition in the treatment group during the weaning period (p < 0.05). In Trial 3, with its lower mean water temperatures of 23.2 °C, larvae in both treatments showed stunted absolute growth rates of all biometrics when compared to results from the higher mean temperatures of Trials 1 and 2. During the first 6 days of Trial 3 larvae were in relatively poor condition, BD:SL ≤ 0.30. During this same period in Trials 1 and 2, mean BD:SL ≥ 0.31, suggesting that a BD:SL ratio of ≤ 0.30 in non-weaned dusky kob larvae is an indicator of a degree of starvation. A future study on the morphology and histology of the larval gastrointestinal tract, specifically the liver and intestines, and how this early weaning regime affects their ontogeny under differing temperature conditions this needed to investigate the validity of these initial data on dusky kob larvae condition.
- Full Text:
Characterisation of surfaces modified with phthalocyanines through click chemistry for applications in electrochemical sensing
- O'Donoghue, Charles St John Nqwabuko
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
- Authors: O'Donoghue, Charles St John Nqwabuko
- Date: 2018
- Subjects: Electrodes, Carbon , Phthalocyanines , X-ray photoelectron spectroscopy , Electrochemistry , Electrochemical sensors , Hydrazine , Click chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58046 , vital:27038
- Description: One form of surface modification was primarily investigated in this work on glassy carbon electrodes. The form of modification is comprised of a series of steps in which electrografting is first applied to the glassy carbon surface, which is then followed up with click chemistry to ultimately immobilise a phthalocyanine onto the surface. The modified glassy carbon electrodes and surfaces were characterised with a combination of scanning electrochemical microscopy, X-ray photoelectron spectroscopy and various electrochemical methods. In this work, three alkyne substituted phthalocyanines were used. Two novel phthalocyanines, with nickel and cobalt metal centres, were studied alongside a manganese phthalocyanine reported in literature. Each of the three phthalocyanines was modified at the peripheral position with a 1-hexyne group, via a glycosidic bond, yielding the terminal alkyne groups that were used for subsequent click reactions. In situ diazotisation was used to graft 4-azidoaniline groups to the surface of the glassy carbon electrode. The azide bearing 4- azidoaniline groups were thus used to anchor the tetra substituted phthalocyanines to the surface of the electrodes. This method yielded successful modification of the electrodes and lead to their application in sensing studies. The modified electrodes were primarily used to catalyse the common agricultural oxidising agent hydrazine.
- Full Text:
How the roles of CEO's differ in response to different circumstances and in the context of succession: Anglo American-a case study
- Authors: Ball, Leslie
- Date: 2018
- Subjects: Organizational change , Strategic planning , Executive succession , Anglo American Corporation of South Africa, ltd.
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/60799 , vital:27832
- Description: A review of the literature revealed that firms are inherently influenced by leadership in the upper echelons of the organization. The seminal paper of Hambrick and Mason (1984) has sparked much interest in the realm of organizational leadership. Studies involving organizational leadership have concentrated on leadership styles, the manner in which leadership takes place, leadership succession and organizational performance in an attempt to understand the dynamics of the senior leadership of organizations. Research has also explored how changes in the top management of firms has impacted its performance. This research has primarily been concerned with how a firm is impacted, once succession takes place, and has focused on financial performance, change in strategy and stockholder reaction (Shen & Cannella, 2002; Barron, Chulkov & Waddell, 2011; Friedman & Singh, 1989). Although their predisposition will largely influence the manner in which the incoming CEO acts, the literature has largely neglected the role the incoming CEO must fulfil, and how he/she steers the company, once appointed. In response, the following aim was developed to address this gap: To describe how the roles of two CEO's of the same company differed, during different time periods. The CEO assumes various strategic leadership roles, which they carry out in the context of their new environment once succession has taken place. From the literature, six strategic leadership roles were identified, which formed the foundation of this study. These were strategy formulation, strategy implementation, developing organizational culture, emphasizing ethical practices, managing the firm's resource portfolio and establishing balanced controls. The study set out to comparatively analyze two CEO's of the same firm during different periods. Both CEO's were investigated from the perspective of strategic leadership roles, allowing a comparison of their behaviour. The study analyses and describes these roles, and how they differed between the CEO's, in reaction to differing situational factors and in the context of succession. The study employed a deductive qualitative case study research design. This allowed the researcher to examine the complex phenomenon which have previously been studied at a more superficial level using quantitative methods (Baxter & Jack, 2008; Parrino, 1997; Jooste & Fourie, 2009). A qualitative methodological approach allowed the researcher to examine the topic through a lens which takes into account human variables and processes (Baxter & Jack, 2008). Data was sampled using purposive and convenience sampling while applying the critical incident technique. Data was collected through information sources such as news articles, press releases, annual reports, online interviews, news websites and other documents. Thematical analysis was used during the analysis phase of the study and allowed for patterns and links to be drawn between the collected data. The succession from one CEO to the next served as the comparative element of the study, which allowed for a contrasting of how both CEO's carried out their strategic leadership roles by adapting to their environment, and how they guided the strategic trajectory of the company. The study also took into account what both CEO's were confronted with at the start of their tenure and how this influenced how they carried out their leadership roles. It was found that Cynthia Carroll exercised her roles in a manner which addressed ethical and stakeholder engagement issues within the business. This was translated directly into how she guided the trajectory of the company. Upon appointment, Mark Cutifani exercised his roles in a manner which addressed the organizational performance and financial well-being of the company. This translated directly into how he shaped Anglo's trajectory in an attempt to better its financial performance. Given how they exercised their strategic roles in the company, each CEO influenced Anglo American's direction in a different way, which in turn, influenced the performance of the organization. It was shown that Cynthia Carroll improved the stakeholder engagement, communication and safety within the company, demonstrating behaviour that emphasized the importance of the ethics of the company. When the business had been carrying out its ethical practices effectively, but underperforming financially, Cutifani demonstrated the roles which would be geared toward resurrecting the organizational performance of the organization. Recommendations are made for further research including applying the same research method to investigate how these roles are carried out in companies which operate in a broad spectrum of industries.
- Full Text:
- Authors: Ball, Leslie
- Date: 2018
- Subjects: Organizational change , Strategic planning , Executive succession , Anglo American Corporation of South Africa, ltd.
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/60799 , vital:27832
- Description: A review of the literature revealed that firms are inherently influenced by leadership in the upper echelons of the organization. The seminal paper of Hambrick and Mason (1984) has sparked much interest in the realm of organizational leadership. Studies involving organizational leadership have concentrated on leadership styles, the manner in which leadership takes place, leadership succession and organizational performance in an attempt to understand the dynamics of the senior leadership of organizations. Research has also explored how changes in the top management of firms has impacted its performance. This research has primarily been concerned with how a firm is impacted, once succession takes place, and has focused on financial performance, change in strategy and stockholder reaction (Shen & Cannella, 2002; Barron, Chulkov & Waddell, 2011; Friedman & Singh, 1989). Although their predisposition will largely influence the manner in which the incoming CEO acts, the literature has largely neglected the role the incoming CEO must fulfil, and how he/she steers the company, once appointed. In response, the following aim was developed to address this gap: To describe how the roles of two CEO's of the same company differed, during different time periods. The CEO assumes various strategic leadership roles, which they carry out in the context of their new environment once succession has taken place. From the literature, six strategic leadership roles were identified, which formed the foundation of this study. These were strategy formulation, strategy implementation, developing organizational culture, emphasizing ethical practices, managing the firm's resource portfolio and establishing balanced controls. The study set out to comparatively analyze two CEO's of the same firm during different periods. Both CEO's were investigated from the perspective of strategic leadership roles, allowing a comparison of their behaviour. The study analyses and describes these roles, and how they differed between the CEO's, in reaction to differing situational factors and in the context of succession. The study employed a deductive qualitative case study research design. This allowed the researcher to examine the complex phenomenon which have previously been studied at a more superficial level using quantitative methods (Baxter & Jack, 2008; Parrino, 1997; Jooste & Fourie, 2009). A qualitative methodological approach allowed the researcher to examine the topic through a lens which takes into account human variables and processes (Baxter & Jack, 2008). Data was sampled using purposive and convenience sampling while applying the critical incident technique. Data was collected through information sources such as news articles, press releases, annual reports, online interviews, news websites and other documents. Thematical analysis was used during the analysis phase of the study and allowed for patterns and links to be drawn between the collected data. The succession from one CEO to the next served as the comparative element of the study, which allowed for a contrasting of how both CEO's carried out their strategic leadership roles by adapting to their environment, and how they guided the strategic trajectory of the company. The study also took into account what both CEO's were confronted with at the start of their tenure and how this influenced how they carried out their leadership roles. It was found that Cynthia Carroll exercised her roles in a manner which addressed ethical and stakeholder engagement issues within the business. This was translated directly into how she guided the trajectory of the company. Upon appointment, Mark Cutifani exercised his roles in a manner which addressed the organizational performance and financial well-being of the company. This translated directly into how he shaped Anglo's trajectory in an attempt to better its financial performance. Given how they exercised their strategic roles in the company, each CEO influenced Anglo American's direction in a different way, which in turn, influenced the performance of the organization. It was shown that Cynthia Carroll improved the stakeholder engagement, communication and safety within the company, demonstrating behaviour that emphasized the importance of the ethics of the company. When the business had been carrying out its ethical practices effectively, but underperforming financially, Cutifani demonstrated the roles which would be geared toward resurrecting the organizational performance of the organization. Recommendations are made for further research including applying the same research method to investigate how these roles are carried out in companies which operate in a broad spectrum of industries.
- Full Text:
Middle management communication in the midst of a crisis
- Authors: Mbolekwano, Veliswa A
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/52477 , vital:26194
- Description: Crisis communication by organisational top leadership to external stakeholders has been explored in literature, while internal crisis communication dynamics by middle managers with their employees within the organisation has been under studied. This paper pursues an understanding of crisis communication dynamics between middle management and their subordinates by investigating how the Middle Managers/Team Leaders of Makana Brick Manufacturing Firm (MBMF) communicated with their employees in the midst of the Eskom load shedding crisis in 2014. The investigation is not limited only to how they handled or made sense of the crisis, but also examines the effect and efficiency of their daily communication on both employees (subordinates) and operations in pursuing this end. As a foundation and background, the study broadly explores the literature on Crisis Leadership, Crisis and Crisis Communication, which are critical topics to understanding the communication role of the middle managers who were the primary subject of this research. The research was conducted through semi-structured, face-to-face interviews. Nine Team Leaders were interviewed. The data collected was transcribed verbatim and analysed through open coding. In the literature of crisis management, the concept of crisis communication has been extensively examined as a function of crisis management, primarily with regards to the crisis communication strategy, encompassing the actual verbal and nonverbal responses an organisation uses to address a crisis. The findings are generally congruent with the crisis communication literature, and reinforce the importance of efficient internal communication in building a culture of transparency between management and employees, as espoused in the literature reviewed, which in addition presents an invaluable opportunity for employees across all levels to engage in and be informed of the organisation’s priorities and therefore has the potential to dictate the success or failure of any major change or crisis situation. As such, it can be argued that there is a need for the same analytical rigour that is given to external crisis communication to be given to financial or operational measures (Barrett, 2002). For both external and internal stakeholders, human compassion, concern and empathy; faith in legitimate and appropriate actions taken by the chosen organisation spokesperson; and honesty, candidness and openness in communication (Seeger 2006, p. 242) are universal. The quality and the quantity of communication, essentially, affect the level of trust and involvement of employees (Thomas, Zolin & Hartman, 2009), which is particularly relevant in times of crisis (Mazzei & Ravazzani, 2015 p. 322). Trust must be developed with staff through clear, honest communication and transparent actions. These encompass being fair, open in communication and intentions, showing consistency, fulfilling promises and being honest about what middle managers can and cannot communicate to their employees (Farrel & Schlesinger, 2013, p. 125). In this study, face to face communication proved to be the most preferred communication channel because of its rewarding advantages such as direct feedback, two-way communication, relationship building and project collaboration.
- Full Text:
- Authors: Mbolekwano, Veliswa A
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/52477 , vital:26194
- Description: Crisis communication by organisational top leadership to external stakeholders has been explored in literature, while internal crisis communication dynamics by middle managers with their employees within the organisation has been under studied. This paper pursues an understanding of crisis communication dynamics between middle management and their subordinates by investigating how the Middle Managers/Team Leaders of Makana Brick Manufacturing Firm (MBMF) communicated with their employees in the midst of the Eskom load shedding crisis in 2014. The investigation is not limited only to how they handled or made sense of the crisis, but also examines the effect and efficiency of their daily communication on both employees (subordinates) and operations in pursuing this end. As a foundation and background, the study broadly explores the literature on Crisis Leadership, Crisis and Crisis Communication, which are critical topics to understanding the communication role of the middle managers who were the primary subject of this research. The research was conducted through semi-structured, face-to-face interviews. Nine Team Leaders were interviewed. The data collected was transcribed verbatim and analysed through open coding. In the literature of crisis management, the concept of crisis communication has been extensively examined as a function of crisis management, primarily with regards to the crisis communication strategy, encompassing the actual verbal and nonverbal responses an organisation uses to address a crisis. The findings are generally congruent with the crisis communication literature, and reinforce the importance of efficient internal communication in building a culture of transparency between management and employees, as espoused in the literature reviewed, which in addition presents an invaluable opportunity for employees across all levels to engage in and be informed of the organisation’s priorities and therefore has the potential to dictate the success or failure of any major change or crisis situation. As such, it can be argued that there is a need for the same analytical rigour that is given to external crisis communication to be given to financial or operational measures (Barrett, 2002). For both external and internal stakeholders, human compassion, concern and empathy; faith in legitimate and appropriate actions taken by the chosen organisation spokesperson; and honesty, candidness and openness in communication (Seeger 2006, p. 242) are universal. The quality and the quantity of communication, essentially, affect the level of trust and involvement of employees (Thomas, Zolin & Hartman, 2009), which is particularly relevant in times of crisis (Mazzei & Ravazzani, 2015 p. 322). Trust must be developed with staff through clear, honest communication and transparent actions. These encompass being fair, open in communication and intentions, showing consistency, fulfilling promises and being honest about what middle managers can and cannot communicate to their employees (Farrel & Schlesinger, 2013, p. 125). In this study, face to face communication proved to be the most preferred communication channel because of its rewarding advantages such as direct feedback, two-way communication, relationship building and project collaboration.
- Full Text:
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