The characterisation of an openwork block deposit, northern buttress, Vesleskarvet, Dronning Maud Land, Antarctica.
- Authors: Hansen, Christel Dorothee
- Date: 2014
- Subjects: Formations (Geology) -- Antarctica -- Queen Maud Land , Geology, Structural -- Antarctica -- Queen Maud Land , Weathering -- Antarctica -- Queen Maud Land , Climatic changes -- Antarctica -- Queen Maud Land , Physical geography -- Antarctica -- Queen Maud Land , Paleoclimatology -- Antarctica
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4878 , http://hdl.handle.net/10962/d1013138
- Description: Investigating openwork block accumulation has the potential to further our understanding of rock weathering, the control of geological structure on landforms, the production of substrates for biological colonisation and the impacts of climate change on landform development and dynamics. Various models for the development of these landforms have been proposed. This includes in situ weathering, frost heave and wedging. Furthermore, it has been suggested that cold-based ice has the potential to preserve these features rather than to obliterate them. Blocky deposits are also frequently used as proxy evidence for interpreting palaeoclimates. The morphology and processes acting on a blockfield located on the Northern Buttress of the Vesleskarvet Nunataks, Dronning Maud Land, Antarctica (2°W, 71°S) were investigated and characterised. Given block dimensions and orientations that closely resembled the parent material and only small differences in aspect related characteristics observed, the blockfield was found to be autochthonous with in situ block production and of a young (Holocene) age. Small differences in rock hardness measurements suggest some form of aspect control on rock weathering. South-facing sides of clasts were found to be the least weathered. In comparison, consistently low rock hardness rebound values for the north-facing aspects suggest that these are the most weathered sides. Additional indicators of weathering, such as flaking and pitting, support analyses conducted for rock hardness rebound values. Solar radiation received, slope gradients and snow cover were found to influence weathering of clasts across the study site. Furthermore, ambient temperatures and wind speed significantly influenced near-surface ground temperatures dynamics. However, the lack of a matrix and paucity of fine material in textural analyses suggest a limited weathering environment. It is suggested that the retreat of the Antarctic ice sheet during the last LGM led to unloading of the surface, causing dilatation and subsequent fracturing of the bedrock along pre-existing joints, leading to in situ clast supply. Subsequent weathering and erosion along other points or lines of weakness then yielded fines and slight edge rounding of clasts.
- Full Text:
- Date Issued: 2014
- Authors: Hansen, Christel Dorothee
- Date: 2014
- Subjects: Formations (Geology) -- Antarctica -- Queen Maud Land , Geology, Structural -- Antarctica -- Queen Maud Land , Weathering -- Antarctica -- Queen Maud Land , Climatic changes -- Antarctica -- Queen Maud Land , Physical geography -- Antarctica -- Queen Maud Land , Paleoclimatology -- Antarctica
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4878 , http://hdl.handle.net/10962/d1013138
- Description: Investigating openwork block accumulation has the potential to further our understanding of rock weathering, the control of geological structure on landforms, the production of substrates for biological colonisation and the impacts of climate change on landform development and dynamics. Various models for the development of these landforms have been proposed. This includes in situ weathering, frost heave and wedging. Furthermore, it has been suggested that cold-based ice has the potential to preserve these features rather than to obliterate them. Blocky deposits are also frequently used as proxy evidence for interpreting palaeoclimates. The morphology and processes acting on a blockfield located on the Northern Buttress of the Vesleskarvet Nunataks, Dronning Maud Land, Antarctica (2°W, 71°S) were investigated and characterised. Given block dimensions and orientations that closely resembled the parent material and only small differences in aspect related characteristics observed, the blockfield was found to be autochthonous with in situ block production and of a young (Holocene) age. Small differences in rock hardness measurements suggest some form of aspect control on rock weathering. South-facing sides of clasts were found to be the least weathered. In comparison, consistently low rock hardness rebound values for the north-facing aspects suggest that these are the most weathered sides. Additional indicators of weathering, such as flaking and pitting, support analyses conducted for rock hardness rebound values. Solar radiation received, slope gradients and snow cover were found to influence weathering of clasts across the study site. Furthermore, ambient temperatures and wind speed significantly influenced near-surface ground temperatures dynamics. However, the lack of a matrix and paucity of fine material in textural analyses suggest a limited weathering environment. It is suggested that the retreat of the Antarctic ice sheet during the last LGM led to unloading of the surface, causing dilatation and subsequent fracturing of the bedrock along pre-existing joints, leading to in situ clast supply. Subsequent weathering and erosion along other points or lines of weakness then yielded fines and slight edge rounding of clasts.
- Full Text:
- Date Issued: 2014
The impact of labour laws on small firms : a study of employer perceptions of the Labour Relations Act (66 of 1995) and the Basic Conditions of Employment Act (75 of 1997) in Grahamstown, Port Alfred and Port Elizabeth
- Authors: Mfecane, Asanda
- Date: 2014 , 2014-07-10
- Subjects: Industrial relations -- South Africa -- Eastern Cape , Labor laws and legislation -- South Africa -- Eastern Cape , Industrial laws and legislation -- South Africa -- Eastern Cape , Small business -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3371 , http://hdl.handle.net/10962/d1012953
- Description: This study sought to explore and explain the impact of labour laws on small firms, focusing on employer perceptions of the Labour Relations Act of 1995 and the Basic Conditions of Employment Act of 1997 in three towns of the Eastern Cape. It is important to focus on this impact of labour laws on these firms because of the high unemployment that faces the country. In this regard, it must be emphasised, firstly, that small firms are central to job creation; therefore, they contribute to a reduction in the unemployment rate; hence, the strategies created by the government to reduce any burdens (including regulatory burdens) on small firms. It is therefore important to study the impact of labour law on small businesses in order to assess the regulatory burden on small firms. The theoretical framework which underpins this study on the impact of labour law on small firms arises from the neo-corporatist critique of neo-liberalism. The two frameworks maintain the extent to which the government should intervene in the industrial relations system. Liberalism maintains that there should be a minimum role of the government, which involves only the facilitation of a framework for negotiations between employers and employees. Corporatism, however, maintains a social democratic approach, and holds that there should be an active role of the government in the industrial relations system with business, labour and the state working co-operatively (Klerck, 2009). This theoretical framework therefore shapes the extent to which employers perceive labour laws or state’s regulatory role impacts small businesses. The data was collected through the qualitative inquiry; using face-to-face, semi-structured interviews. The findings in this study included negative employer perceptions of labour laws. More specifically, many of the employers that were interviewed claimed that labour laws were burdensome on their businesses. They claimed that labour laws imposed financial and administrative costs to their firms, negatively affected the employer-employee relationships in these firms as well as the employing decisions of the employers. As a result, the employers saw labour laws as undermining flexibility and imposing unfair rigidities on small firms. Furthermore, employers perceived South African labour laws as not addressing the unique iii circumstances of small firms. They maintained that labour laws treated small firms similarly to large firms. Even though the employers held these perceptions of labour laws, it was evident that these subjective perceptions did not reflect the objective impact of labour laws on small firms. This was firstly related to the fact that many of the employers that were interviewed had negative views of labour laws but these views were not substantiated by particular events in their firms. Secondly, it was revealed that the employers’ perceptions of labour laws were based on their misconception or misunderstanding of labour law. Thirdly, it was revealed in this thesis that small firms were not affected in the same way to big firms by labour regulation. This was related to the fact that many of the small firms’ employers that were interviewed tended to be less concerned by regulation. Specifically, although many employers that were interviewed claimed that labour laws were burdensome on their firms it was evident that regulation was avoided because of the informality that characterised these firms. Consequently informality mediated the impact of labour laws on these firms, and labour laws imposed less ‘costs’ on these firms. However, it cannot be argued that small firms are isolated from the sphere of labour laws. Rather, although these firms were governed by regulation it was found that the extent to which employers complied with regulation depended on the extent to which organisational practice already reflected similarity with the legislative objective. , Acrobat PDFMaker 10.1 for Word , Adobe PDF Library 10.0
- Full Text:
- Date Issued: 2014
- Authors: Mfecane, Asanda
- Date: 2014 , 2014-07-10
- Subjects: Industrial relations -- South Africa -- Eastern Cape , Labor laws and legislation -- South Africa -- Eastern Cape , Industrial laws and legislation -- South Africa -- Eastern Cape , Small business -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3371 , http://hdl.handle.net/10962/d1012953
- Description: This study sought to explore and explain the impact of labour laws on small firms, focusing on employer perceptions of the Labour Relations Act of 1995 and the Basic Conditions of Employment Act of 1997 in three towns of the Eastern Cape. It is important to focus on this impact of labour laws on these firms because of the high unemployment that faces the country. In this regard, it must be emphasised, firstly, that small firms are central to job creation; therefore, they contribute to a reduction in the unemployment rate; hence, the strategies created by the government to reduce any burdens (including regulatory burdens) on small firms. It is therefore important to study the impact of labour law on small businesses in order to assess the regulatory burden on small firms. The theoretical framework which underpins this study on the impact of labour law on small firms arises from the neo-corporatist critique of neo-liberalism. The two frameworks maintain the extent to which the government should intervene in the industrial relations system. Liberalism maintains that there should be a minimum role of the government, which involves only the facilitation of a framework for negotiations between employers and employees. Corporatism, however, maintains a social democratic approach, and holds that there should be an active role of the government in the industrial relations system with business, labour and the state working co-operatively (Klerck, 2009). This theoretical framework therefore shapes the extent to which employers perceive labour laws or state’s regulatory role impacts small businesses. The data was collected through the qualitative inquiry; using face-to-face, semi-structured interviews. The findings in this study included negative employer perceptions of labour laws. More specifically, many of the employers that were interviewed claimed that labour laws were burdensome on their businesses. They claimed that labour laws imposed financial and administrative costs to their firms, negatively affected the employer-employee relationships in these firms as well as the employing decisions of the employers. As a result, the employers saw labour laws as undermining flexibility and imposing unfair rigidities on small firms. Furthermore, employers perceived South African labour laws as not addressing the unique iii circumstances of small firms. They maintained that labour laws treated small firms similarly to large firms. Even though the employers held these perceptions of labour laws, it was evident that these subjective perceptions did not reflect the objective impact of labour laws on small firms. This was firstly related to the fact that many of the employers that were interviewed had negative views of labour laws but these views were not substantiated by particular events in their firms. Secondly, it was revealed that the employers’ perceptions of labour laws were based on their misconception or misunderstanding of labour law. Thirdly, it was revealed in this thesis that small firms were not affected in the same way to big firms by labour regulation. This was related to the fact that many of the small firms’ employers that were interviewed tended to be less concerned by regulation. Specifically, although many employers that were interviewed claimed that labour laws were burdensome on their firms it was evident that regulation was avoided because of the informality that characterised these firms. Consequently informality mediated the impact of labour laws on these firms, and labour laws imposed less ‘costs’ on these firms. However, it cannot be argued that small firms are isolated from the sphere of labour laws. Rather, although these firms were governed by regulation it was found that the extent to which employers complied with regulation depended on the extent to which organisational practice already reflected similarity with the legislative objective. , Acrobat PDFMaker 10.1 for Word , Adobe PDF Library 10.0
- Full Text:
- Date Issued: 2014
Sending and receiving: immunity sought by diplomats committing criminal offences
- Authors: Moutzouris, Maria
- Date: 2009
- Subjects: Diplomatic privileges and immunities , International crimes , Criminal law , International law
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3686 , http://hdl.handle.net/10962/d1003201 , Diplomatic privileges and immunities , International crimes , Criminal law , International law
- Description: Diplomatic immunity is one of the oldest elements of foreign relations, dating back as far as Ancient Greece and Rome. Today, it is a principle that has been codified into the Vienna Convention on Diplomatic Relations regulating past customs and practices. Consuls and international organizations, although their privileges and immunities are similar to diplomatic personnel, do differ and are regulated by the Vienna Convention on Consular Relations and the United Nations International Immunities respectively. These Conventions have been influenced by past practices and by three theories during different era’s namely exterritoriality, personal representation and functional necessity. The Vienna Convention on Diplomatic Relations further provides certain immunities and privileges to different levels of diplomatic officials, their staff and families. Privileges and immunities will be considered under various main categories, namely the diplomatic mission, the diplomatic official, diplomatic staff, and families. Each category receives privileges and immunities, for example immunities enjoyed by the diplomatic mission include mission correspondence and bags. Diplomatic officials enjoy personal inviolability, immunity from jurisdiction and inviolability of diplomats’ residences and property. The staff and families of diplomatic officials too enjoy privileges and immunities. The problem of so many people receiving privileges and immunities is that there is a high likelihood of abuse. Abuses that arise are various crimes committed by diplomats, their staff and families. They are immune from local punishment and appear to be above the local law. Although the Vienna Convention on Diplomatic Relations provides remedies against diplomats, staff and families who abuse their position, it gives the impression that it is not enough. Various Acts in the United Kingdom, United States and the Republic of South Africa will be analysed in order to ascertain what governments have done to try and curb diplomatic abuses. Each will be considered and found that although they have restricted immunity from previous practices it still places the diplomats’ needs above its own citizens. Thus several suggestions have been put forward and argued whether they are successful in restricting immunity comprehensively. Such suggestions are amending the Vienna Convention on Diplomatic Relations; using the functional necessity theory to further limit immunity; forming bilateral treaties between States as a possible means to restrict or limit; and lastly establishing a Permanent International Diplomatic Criminal Court. The key question to be answered is whether diplomatic immunity is needed for the efficient functioning of foreign relations between States.
- Full Text:
- Date Issued: 2009
- Authors: Moutzouris, Maria
- Date: 2009
- Subjects: Diplomatic privileges and immunities , International crimes , Criminal law , International law
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3686 , http://hdl.handle.net/10962/d1003201 , Diplomatic privileges and immunities , International crimes , Criminal law , International law
- Description: Diplomatic immunity is one of the oldest elements of foreign relations, dating back as far as Ancient Greece and Rome. Today, it is a principle that has been codified into the Vienna Convention on Diplomatic Relations regulating past customs and practices. Consuls and international organizations, although their privileges and immunities are similar to diplomatic personnel, do differ and are regulated by the Vienna Convention on Consular Relations and the United Nations International Immunities respectively. These Conventions have been influenced by past practices and by three theories during different era’s namely exterritoriality, personal representation and functional necessity. The Vienna Convention on Diplomatic Relations further provides certain immunities and privileges to different levels of diplomatic officials, their staff and families. Privileges and immunities will be considered under various main categories, namely the diplomatic mission, the diplomatic official, diplomatic staff, and families. Each category receives privileges and immunities, for example immunities enjoyed by the diplomatic mission include mission correspondence and bags. Diplomatic officials enjoy personal inviolability, immunity from jurisdiction and inviolability of diplomats’ residences and property. The staff and families of diplomatic officials too enjoy privileges and immunities. The problem of so many people receiving privileges and immunities is that there is a high likelihood of abuse. Abuses that arise are various crimes committed by diplomats, their staff and families. They are immune from local punishment and appear to be above the local law. Although the Vienna Convention on Diplomatic Relations provides remedies against diplomats, staff and families who abuse their position, it gives the impression that it is not enough. Various Acts in the United Kingdom, United States and the Republic of South Africa will be analysed in order to ascertain what governments have done to try and curb diplomatic abuses. Each will be considered and found that although they have restricted immunity from previous practices it still places the diplomats’ needs above its own citizens. Thus several suggestions have been put forward and argued whether they are successful in restricting immunity comprehensively. Such suggestions are amending the Vienna Convention on Diplomatic Relations; using the functional necessity theory to further limit immunity; forming bilateral treaties between States as a possible means to restrict or limit; and lastly establishing a Permanent International Diplomatic Criminal Court. The key question to be answered is whether diplomatic immunity is needed for the efficient functioning of foreign relations between States.
- Full Text:
- Date Issued: 2009
An investigation into the possible neuroprotective or neurotoxic properties of metrifonate
- Authors: Ramsunder, Adrusha
- Date: 2005 , 2013-06-11
- Subjects: Nervous system -- Degeneration -- Treatment , Neurotoxic agents , Alzheimer's disease -- Treatment , Metrifonate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3833 , http://hdl.handle.net/10962/d1007560 , Nervous system -- Degeneration -- Treatment , Neurotoxic agents , Alzheimer's disease -- Treatment , Metrifonate
- Description: Alzheimer's disease is a progressive neurodegenerative disorder, in which there is a marked decline in neurotransmitters, especially those of the cholinergic pathways. One of the approaches to the symptomatic treatment of Alzheimer's disease is the inhibition of the breakdown of the neurotransmitter acetylcholine, using an acetylcholinesterase inhibitor. One such drug tested, is the organophosphate, metrifonate. Any drug used for the treatment of neurodegenerative disorders should preferably not induce further neurological damage. Thus, in the present study, we investigated whether or not metrifonate is neuroprotective. The in vivo and in vitro effect of this drug on free radicals generation shows that metrifonate increases the level ofthese reactive species. Lipid peroxidation induced using quinolinic acid (QA) and iron (II) and show that metrifonate increased the peroxidative damage induced by using quinolinic acid. Metrifonate is also able to induce lipid peroxidation both in vivo and in vitro. This was reduced in vitro in the presence of melatonin. Using iron (II), in vi/ro, there was no significant difference in the level of lipid peroxidation in the presence of this drug. An investigation of the activity of the mitochondrial electron transport chain and complex I of the electron transport chain in the presence of metrifonate revealed that metrifonate reduces the activity of the electron transport chain at the level of complex I. The activity of the mitochondrial electron transport chain was restored in the presence of melatonin. Pineal organ culture showed that metrifonate does not increase melatonin production. Histological and apoptosis studies show that tissue necrosis and apoptosis respectively, occur in the presence of this agent, which is reduced in the presence of melatonin. Metal binding studies were performed USing ultraviolet spectroscopy, and electrochemical analysis to examine the interaction of metrifonate with iron (II) and iron (III). No shift in the peak was observed in the ultraviolet spectrum when iron (ll) was added to metrifonate. Electrochemical studies show that there may be a very weak or no ligand formed between the metal and drug. This study shows that while drugs such as metrifonate may be beneficial in restoring cognitive function in Alzheimer's disease, it could also have the potential to enhance neurodegeneration, thus worsening the condition, in the long term. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2005
- Authors: Ramsunder, Adrusha
- Date: 2005 , 2013-06-11
- Subjects: Nervous system -- Degeneration -- Treatment , Neurotoxic agents , Alzheimer's disease -- Treatment , Metrifonate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3833 , http://hdl.handle.net/10962/d1007560 , Nervous system -- Degeneration -- Treatment , Neurotoxic agents , Alzheimer's disease -- Treatment , Metrifonate
- Description: Alzheimer's disease is a progressive neurodegenerative disorder, in which there is a marked decline in neurotransmitters, especially those of the cholinergic pathways. One of the approaches to the symptomatic treatment of Alzheimer's disease is the inhibition of the breakdown of the neurotransmitter acetylcholine, using an acetylcholinesterase inhibitor. One such drug tested, is the organophosphate, metrifonate. Any drug used for the treatment of neurodegenerative disorders should preferably not induce further neurological damage. Thus, in the present study, we investigated whether or not metrifonate is neuroprotective. The in vivo and in vitro effect of this drug on free radicals generation shows that metrifonate increases the level ofthese reactive species. Lipid peroxidation induced using quinolinic acid (QA) and iron (II) and show that metrifonate increased the peroxidative damage induced by using quinolinic acid. Metrifonate is also able to induce lipid peroxidation both in vivo and in vitro. This was reduced in vitro in the presence of melatonin. Using iron (II), in vi/ro, there was no significant difference in the level of lipid peroxidation in the presence of this drug. An investigation of the activity of the mitochondrial electron transport chain and complex I of the electron transport chain in the presence of metrifonate revealed that metrifonate reduces the activity of the electron transport chain at the level of complex I. The activity of the mitochondrial electron transport chain was restored in the presence of melatonin. Pineal organ culture showed that metrifonate does not increase melatonin production. Histological and apoptosis studies show that tissue necrosis and apoptosis respectively, occur in the presence of this agent, which is reduced in the presence of melatonin. Metal binding studies were performed USing ultraviolet spectroscopy, and electrochemical analysis to examine the interaction of metrifonate with iron (II) and iron (III). No shift in the peak was observed in the ultraviolet spectrum when iron (ll) was added to metrifonate. Electrochemical studies show that there may be a very weak or no ligand formed between the metal and drug. This study shows that while drugs such as metrifonate may be beneficial in restoring cognitive function in Alzheimer's disease, it could also have the potential to enhance neurodegeneration, thus worsening the condition, in the long term. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2005
The biotechnology of effluent-grown Spirulina, and application in aquaculture nutrition
- Authors: Maart, Brenton Ashley
- Date: 1993
- Subjects: Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4050 , http://hdl.handle.net/10962/d1004111 , Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Description: The biotechnology of production and utilisation of the cyanobacterium Spirulina has been well documented. Research has centred mainly on application in human and animal nutrition, and has been motivated by the high protein, vitamin, fatty acid and growth factor contents. The main obstacle in realising the full potential of this feed source has been the high production costs associated with its mass culture in defined media. The observation of blooms of Spirulina in tannery effluent evaporation ponds in Wellington, South Africa, prompted this investigation into the harvesting, and nutritional and toxicological evaluation of this potentially low-cost production system, with the ultimate aim of using the product in aquaculture rations. An investigation of the chemical gradient along the evaporation cascade showed a positive correlation between the prevailing chemical conditions and the dominant species populations. A standing crop of 9.5 tonnes/ha of Spirulina was found to be present in the latter alkaline ponds, characterised by relatively lower organic and sulphur contents. Initial harvesting of the biomass was achieved by the design, construction and implementation of a small-scale screen harvest, which yielded a 25 kg (dry weight) crop. A scale-up model was then designed, and implemented in a technical scale harvest, yielding a crop of 250 kg (dry weight). Both these harvests utilised the bloom of surface-autoflocculated biomass. Concentrated cell slurries were sun-dried on muslin beds, and milled to a coarse powder. An evaluation of the harvest revealed a chemical content similar to other published reports of defined media cultures, with the exception of the protein and amino acid contents. The observed lower levels of the latter two are almost certainly due to the sun-drying method employed, known to reduce the protein content due to thermal denaturation. Legislation demands the strict toxicological evaluation of new protein sources, and because of the effluent-nature of the growth medium of this source of Spirulina, its viability lies only in the application as an animal feed or supplement. A range of toxicological tests were chosen that were targeted to elucidate the possible toxicological constraints of this effluentgrown source of protein in animal nutrition. The nucleic acid and pesticide contents of the harvested biomass were within the prescribed safety ranges. Atomic absorption showed minimal accumulation of minerals and heavy metals from the effluent. A bioassay with the brine shrimp Anemia salina showed that the biomass contained no toxicologically active water-soluble components. A short term feeding trial with new-born chicks showed that supplementation with Spirulina had no effect on the growth rates and feed conversion ratios of the different feeding groups. Pathological analyses showed that the liver was the only target organ to elicit a change in response to supplementation of the diets with Spirulina. A general decrease in liver weight was noted, with Cu, Ca, Fe and Zn being significantly accumulated. A histopathological examination however, showed no cellular and functional aberration from the control animals. The toxicological analyses gave the preliminary safe go-ahead for the evaluation of effluent-grown Spirulina in aquaculture nutrition. The South African abalone Haliotis midae, and the rainbow trout Oncorhynchus mykiss were chosen as representative species of edible cultured organisms. The technology for the culture of the perlemoen abalone is being established in South Africa, with the main area of research being the development of an artificial diet for high density culture. A 40 day growth trial demonstrated that lower concentrations of Spirulina supplemented to an agar-based fishmeal diet resulted in growth rates and feed conversion ratios similar to the control fishmeal and purified-casein diets, and thus has application potential in the nutrition of this high-cost marine delicacy. The aquaculture technology of freshwater rainbow trout is already well established. An eight week feeding trial with various concentrations of Spirulina showed that this effluent-grown protein source can partially replace fishmeal in semi-purified diets. Fish fed Spirulina did not exhibit decisive manifestations of toxicity, as determined in a histopathological study. In addition, Spirulina supplementation resulted in enhanced colouration of the skin and flesh, which may have implications in the aesthetic marketing of this sought-after table fish. The primary aim of this preliminary investigation thus concerned the determination of the biotechnological potential of this effluent-source of Spirulina. A technology transfer from the economically unfeasible defined-media culture was implemented. This project is ultimately aimed as a contribution towards the treatment of tannery wastewater, by the removal of contaminants from the effluent in the form of organic biomass.
- Full Text:
- Date Issued: 1993
- Authors: Maart, Brenton Ashley
- Date: 1993
- Subjects: Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4050 , http://hdl.handle.net/10962/d1004111 , Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Description: The biotechnology of production and utilisation of the cyanobacterium Spirulina has been well documented. Research has centred mainly on application in human and animal nutrition, and has been motivated by the high protein, vitamin, fatty acid and growth factor contents. The main obstacle in realising the full potential of this feed source has been the high production costs associated with its mass culture in defined media. The observation of blooms of Spirulina in tannery effluent evaporation ponds in Wellington, South Africa, prompted this investigation into the harvesting, and nutritional and toxicological evaluation of this potentially low-cost production system, with the ultimate aim of using the product in aquaculture rations. An investigation of the chemical gradient along the evaporation cascade showed a positive correlation between the prevailing chemical conditions and the dominant species populations. A standing crop of 9.5 tonnes/ha of Spirulina was found to be present in the latter alkaline ponds, characterised by relatively lower organic and sulphur contents. Initial harvesting of the biomass was achieved by the design, construction and implementation of a small-scale screen harvest, which yielded a 25 kg (dry weight) crop. A scale-up model was then designed, and implemented in a technical scale harvest, yielding a crop of 250 kg (dry weight). Both these harvests utilised the bloom of surface-autoflocculated biomass. Concentrated cell slurries were sun-dried on muslin beds, and milled to a coarse powder. An evaluation of the harvest revealed a chemical content similar to other published reports of defined media cultures, with the exception of the protein and amino acid contents. The observed lower levels of the latter two are almost certainly due to the sun-drying method employed, known to reduce the protein content due to thermal denaturation. Legislation demands the strict toxicological evaluation of new protein sources, and because of the effluent-nature of the growth medium of this source of Spirulina, its viability lies only in the application as an animal feed or supplement. A range of toxicological tests were chosen that were targeted to elucidate the possible toxicological constraints of this effluentgrown source of protein in animal nutrition. The nucleic acid and pesticide contents of the harvested biomass were within the prescribed safety ranges. Atomic absorption showed minimal accumulation of minerals and heavy metals from the effluent. A bioassay with the brine shrimp Anemia salina showed that the biomass contained no toxicologically active water-soluble components. A short term feeding trial with new-born chicks showed that supplementation with Spirulina had no effect on the growth rates and feed conversion ratios of the different feeding groups. Pathological analyses showed that the liver was the only target organ to elicit a change in response to supplementation of the diets with Spirulina. A general decrease in liver weight was noted, with Cu, Ca, Fe and Zn being significantly accumulated. A histopathological examination however, showed no cellular and functional aberration from the control animals. The toxicological analyses gave the preliminary safe go-ahead for the evaluation of effluent-grown Spirulina in aquaculture nutrition. The South African abalone Haliotis midae, and the rainbow trout Oncorhynchus mykiss were chosen as representative species of edible cultured organisms. The technology for the culture of the perlemoen abalone is being established in South Africa, with the main area of research being the development of an artificial diet for high density culture. A 40 day growth trial demonstrated that lower concentrations of Spirulina supplemented to an agar-based fishmeal diet resulted in growth rates and feed conversion ratios similar to the control fishmeal and purified-casein diets, and thus has application potential in the nutrition of this high-cost marine delicacy. The aquaculture technology of freshwater rainbow trout is already well established. An eight week feeding trial with various concentrations of Spirulina showed that this effluent-grown protein source can partially replace fishmeal in semi-purified diets. Fish fed Spirulina did not exhibit decisive manifestations of toxicity, as determined in a histopathological study. In addition, Spirulina supplementation resulted in enhanced colouration of the skin and flesh, which may have implications in the aesthetic marketing of this sought-after table fish. The primary aim of this preliminary investigation thus concerned the determination of the biotechnological potential of this effluent-source of Spirulina. A technology transfer from the economically unfeasible defined-media culture was implemented. This project is ultimately aimed as a contribution towards the treatment of tannery wastewater, by the removal of contaminants from the effluent in the form of organic biomass.
- Full Text:
- Date Issued: 1993
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