The role of the sandprawn, Callichirus kraussi, as an ecosystem engineer in a temporarily open/closed Eastern Cape estuary, South Africa
- Authors: Njozela, Cuma
- Date: 2013
- Subjects: Estuarine biology -- South Africa -- Eastern Cape , Decapoda (Crustacea) -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , Bioenergetics -- South Africa -- Eastern Cape , Shrimps -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5583 , http://hdl.handle.net/10962/d1001539 , Estuarine biology -- South Africa -- Eastern Cape , Decapoda (Crustacea) -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , Bioenergetics -- South Africa -- Eastern Cape , Shrimps -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape
- Description: The role of the sandprawn, Callichirus (=Callianassa) kraussi (Stebbing), as an ecosystem engineer was assessed in the lower reach of the temporarily open/closed Kasouga Estuary situated along the Eastern Cape coastline of southern Africa over the period April 2010 to June 2011. The study comprised two distinct components, a field study and a caging experiment. The field study assessed the correlation between sand prawn densities and selected physico-chemical (organic content of the sediment and bioturbation) and biological (microphytobenthic algal concentrations and macrobenthic abundance and biomass) variables in 50 quadrants in the lower reach of the estuary. Densities of the sand prawn within the quadrants ranged from 0 to 156 ind m⁻² (mean = 37 ind m⁻²). There were no significant correlations between the densities of the sandprawn and the estimates of the organic content of the sediment and the abundance and biomass of the macrofauna (P > 0.05 in all cases). Numerical analyses failed to identify any effect of the sandprawn density on the macrofaunal community structure. The rate of bioturbation was, however, strongly correlated to the sand prawn density. Similarly, the microphytobenthic alga concentrations were significantly negatively correlated to the sand prawn densities ((P < 0.05). The absence of any distinct impact of the sandprawn on the macrobenthic community structure appeared to be related to their low densities in the lower reach of the estuary during the study. To better understand the role of the sandprawn as an ecosystem engineer, a caging experiment was conducted using inclusion and exclusion treatments (n= 5 for each treatment). Densities of the sandprawn in the inclusion treatments (80 ind m⁻²) were in the range of the natural densities within the estuary. The experiment was conducted over a period of 18 weeks in the lower reach of the estuary during summer. The presence of the sandprawn, C kraussi, contributed to a significant decrease in the microphytobenthic algal concentrations and the abundance and biomass of the macrofauna (P < 0.05 in all cases). The decrease in the microphytobenthic algal concentrations in the presence of the sandprawn appeared to be related to the res-suspension of the sediments (bioturbation) generated by the burrowing and feeding activities of the sandprawn. The observed decrease in macrofaunal abundances and biomass in the inclusion treatments appeared to be mediated by both the decreased food availability (mainly the microphytobenthic algae) and the burial of organisms within the sediments. Numerical analysis indicated that the sandprawn did, however, not contribute to a change in the species composition of the macrofauna. Results of the current study indicate that C.kraussi plays an important role in structuring the invertebrate community and energy flow within temporarily/open closed Kasouga Estuary.
- Full Text:
- Date Issued: 2013
- Authors: Njozela, Cuma
- Date: 2013
- Subjects: Estuarine biology -- South Africa -- Eastern Cape , Decapoda (Crustacea) -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , Bioenergetics -- South Africa -- Eastern Cape , Shrimps -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5583 , http://hdl.handle.net/10962/d1001539 , Estuarine biology -- South Africa -- Eastern Cape , Decapoda (Crustacea) -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , Bioenergetics -- South Africa -- Eastern Cape , Shrimps -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape
- Description: The role of the sandprawn, Callichirus (=Callianassa) kraussi (Stebbing), as an ecosystem engineer was assessed in the lower reach of the temporarily open/closed Kasouga Estuary situated along the Eastern Cape coastline of southern Africa over the period April 2010 to June 2011. The study comprised two distinct components, a field study and a caging experiment. The field study assessed the correlation between sand prawn densities and selected physico-chemical (organic content of the sediment and bioturbation) and biological (microphytobenthic algal concentrations and macrobenthic abundance and biomass) variables in 50 quadrants in the lower reach of the estuary. Densities of the sand prawn within the quadrants ranged from 0 to 156 ind m⁻² (mean = 37 ind m⁻²). There were no significant correlations between the densities of the sandprawn and the estimates of the organic content of the sediment and the abundance and biomass of the macrofauna (P > 0.05 in all cases). Numerical analyses failed to identify any effect of the sandprawn density on the macrofaunal community structure. The rate of bioturbation was, however, strongly correlated to the sand prawn density. Similarly, the microphytobenthic alga concentrations were significantly negatively correlated to the sand prawn densities ((P < 0.05). The absence of any distinct impact of the sandprawn on the macrobenthic community structure appeared to be related to their low densities in the lower reach of the estuary during the study. To better understand the role of the sandprawn as an ecosystem engineer, a caging experiment was conducted using inclusion and exclusion treatments (n= 5 for each treatment). Densities of the sandprawn in the inclusion treatments (80 ind m⁻²) were in the range of the natural densities within the estuary. The experiment was conducted over a period of 18 weeks in the lower reach of the estuary during summer. The presence of the sandprawn, C kraussi, contributed to a significant decrease in the microphytobenthic algal concentrations and the abundance and biomass of the macrofauna (P < 0.05 in all cases). The decrease in the microphytobenthic algal concentrations in the presence of the sandprawn appeared to be related to the res-suspension of the sediments (bioturbation) generated by the burrowing and feeding activities of the sandprawn. The observed decrease in macrofaunal abundances and biomass in the inclusion treatments appeared to be mediated by both the decreased food availability (mainly the microphytobenthic algae) and the burial of organisms within the sediments. Numerical analysis indicated that the sandprawn did, however, not contribute to a change in the species composition of the macrofauna. Results of the current study indicate that C.kraussi plays an important role in structuring the invertebrate community and energy flow within temporarily/open closed Kasouga Estuary.
- Full Text:
- Date Issued: 2013
An ion imprinted polymer for the selective extraction of mercury (II) ions in aqueous media
- Authors: Batlokwa, Bareki Shima
- Date: 2010 , 2013-07-18
- Subjects: Mercury , Metal ions , Imprinted polymers , Polymerization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4294 , http://hdl.handle.net/10962/d1004541 , Mercury , Metal ions , Imprinted polymers , Polymerization
- Description: This thesis presents the application of an imprinted mercury(lI) polymer that we synthesized by copolymerizing the functional and cross-linking monomers, N'-[3-(Trimethoxysilyl)propyl] diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS) in the presence of mercury (II) ions as template. A bulk polymerization method following a double-imprinting procedure and employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer was employed in the synthesis. The imprinted polymer particles were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and their average size determined by screen analysis using standard test sieves. The relative selective coefficients (k') of the imprinted polymer evaluated from selective binding studies between Hg ²⁺and Cu²⁺ or Hg²⁺ and Cd²⁺, were 10588 and 3147, respectively. These values indicated highly favored Hg²⁺ extractions over the two competing ions. Application of the polymer to various real water samples (tap, sea, river, pulverized coal solution, treated and untreated sewerage from the vicinity of Grahamstown in South Africa) showed high extraction efficiencies (EEs) of Hg²⁺ ions; (over 84% in all cases) as evaluated from the detected unextracted Hg²⁺ ions by inductively coupled plasma optical emission spectroscopy (ICP-OES). The limit of detection (LOD, 3ơ) of the method was evaluated to be 0.036 ng ml⁻¹ and generally the data (n=10) had percentage relative standard deviation (%RSD) of less than 4%. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre-concentration of mercury(lI) ions in aqueous environments. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2010
- Authors: Batlokwa, Bareki Shima
- Date: 2010 , 2013-07-18
- Subjects: Mercury , Metal ions , Imprinted polymers , Polymerization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4294 , http://hdl.handle.net/10962/d1004541 , Mercury , Metal ions , Imprinted polymers , Polymerization
- Description: This thesis presents the application of an imprinted mercury(lI) polymer that we synthesized by copolymerizing the functional and cross-linking monomers, N'-[3-(Trimethoxysilyl)propyl] diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS) in the presence of mercury (II) ions as template. A bulk polymerization method following a double-imprinting procedure and employing hexadecyltrimethylammonium bromide (CTAB), as a second template to improve the efficiency of the polymer was employed in the synthesis. The imprinted polymer particles were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and their average size determined by screen analysis using standard test sieves. The relative selective coefficients (k') of the imprinted polymer evaluated from selective binding studies between Hg ²⁺and Cu²⁺ or Hg²⁺ and Cd²⁺, were 10588 and 3147, respectively. These values indicated highly favored Hg²⁺ extractions over the two competing ions. Application of the polymer to various real water samples (tap, sea, river, pulverized coal solution, treated and untreated sewerage from the vicinity of Grahamstown in South Africa) showed high extraction efficiencies (EEs) of Hg²⁺ ions; (over 84% in all cases) as evaluated from the detected unextracted Hg²⁺ ions by inductively coupled plasma optical emission spectroscopy (ICP-OES). The limit of detection (LOD, 3ơ) of the method was evaluated to be 0.036 ng ml⁻¹ and generally the data (n=10) had percentage relative standard deviation (%RSD) of less than 4%. These findings indicate that the double-imprinted polymer has potential to be used as an efficient extraction material for the selective pre-concentration of mercury(lI) ions in aqueous environments. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2010
Photophysical studies of zinc and indium tetraaminophthalocyanines in the presence of CdTe quantum dots
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
- Authors: Britton, Jonathan
- Date: 2010
- Subjects: Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4332 , http://hdl.handle.net/10962/d1004993 , Indium , Zinc , Quantum dots , Phthalocyanines , Photochemotherapy , Nonlinear optics , Nanocrystals
- Description: CdTe QDs capped with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) were covalently linked to zinc and indium tetraaminophthalocyanines (TAPcs) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of formation of an amide bond between the MTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and the mixture of QDs and ZnTAPc (without chemical linking) showed Förster resonance energy transfer (FRET), though the linked showed less FRET, whereas the QD interactions with InTAPc yielded no evidence of FRET. Both MTAPcs quenched the QDs emission, with quenching constants of the order of 103–104M−1, binding constants of the order of 108-1010M-1 and the number of binding sites for the MTAPc upon the QD being 2. High energy transfer efficiencies were obtained (in some cases as high as 93%), due to the low donor to acceptor distances. Lastly, both MTAPc were shown to be poor optical limiters because their imaginary third-order susceptibility (Im[χ(3)]) was of the order of 10-17-10-16 (optimal range is 10-9-10-11), the hyperpolarizability (γ) of the order of 10-37-10-36 (optimal range is 10-29-10-34) and the k values were above one but below ten.
- Full Text:
- Date Issued: 2010
The legal effect of a coup d'etat on traditional constitutional concepts
- Authors: Mkwentla, Nelson Koala
- Date: 2002
- Subjects: Coups d'état , Constitutional law
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3684 , http://hdl.handle.net/10962/d1003199 , Coups d'état , Constitutional law
- Description: This thesis deals with constitutional law and other legal subjects such as Jurisprudence and Judicial Review. One constitution is distinguishable from another by its own provisions. These provisions are usually referred to as either the basic characteristics or features of the particular constitution and these are invariably derived from the basic political philosophy and constitutional arrangements of the particular country. A coup affects these characteristics in different ways. Some automatically disappear as being incompatible with the revolution; some are modified, others are strengthened. The usurpers may choose to set aside the constitution completely and replace it with another, or amend it to suit the new situation, or rule without any constitution. This often happens amidst the rattle of weapons and the whirr of military engines in and around the capital of a given country on that awesome occasion. This thesis sets out to examine the legal aspects of a coup d’ etat. The thesis is divided into six broad sections. Part one will deal with the theoretical background. I shall discuss an overview of Kelsen’s pure theory of law. The second part deals with the scope of its application in revolutionary situations and will also touch upon the reason behind the Kelsen’s theory as shown by decided cases from country to country. The third part deals with the essence as well as the significance of the doctrine of necessity to validate unconstitutional acts in the case of a coup d’ etat. This discussion is to pave the way for the fourth part which is to explore the position of judges who took oath of office under the old constitution. I am to explain their position after a coup d’ etat. The fifth part forms the gist of my research. I shall examine the effect of a coup d’ etat on traditional constitutional concepts such as fundamental rights, separation of powers, rule of law and judicial review in the military regime. The sixth part will deal with African experience. I shall include recommendations and conclusions drawn from the Lesotho and Uganda experiences.
- Full Text:
- Date Issued: 2002
- Authors: Mkwentla, Nelson Koala
- Date: 2002
- Subjects: Coups d'état , Constitutional law
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3684 , http://hdl.handle.net/10962/d1003199 , Coups d'état , Constitutional law
- Description: This thesis deals with constitutional law and other legal subjects such as Jurisprudence and Judicial Review. One constitution is distinguishable from another by its own provisions. These provisions are usually referred to as either the basic characteristics or features of the particular constitution and these are invariably derived from the basic political philosophy and constitutional arrangements of the particular country. A coup affects these characteristics in different ways. Some automatically disappear as being incompatible with the revolution; some are modified, others are strengthened. The usurpers may choose to set aside the constitution completely and replace it with another, or amend it to suit the new situation, or rule without any constitution. This often happens amidst the rattle of weapons and the whirr of military engines in and around the capital of a given country on that awesome occasion. This thesis sets out to examine the legal aspects of a coup d’ etat. The thesis is divided into six broad sections. Part one will deal with the theoretical background. I shall discuss an overview of Kelsen’s pure theory of law. The second part deals with the scope of its application in revolutionary situations and will also touch upon the reason behind the Kelsen’s theory as shown by decided cases from country to country. The third part deals with the essence as well as the significance of the doctrine of necessity to validate unconstitutional acts in the case of a coup d’ etat. This discussion is to pave the way for the fourth part which is to explore the position of judges who took oath of office under the old constitution. I am to explain their position after a coup d’ etat. The fifth part forms the gist of my research. I shall examine the effect of a coup d’ etat on traditional constitutional concepts such as fundamental rights, separation of powers, rule of law and judicial review in the military regime. The sixth part will deal with African experience. I shall include recommendations and conclusions drawn from the Lesotho and Uganda experiences.
- Full Text:
- Date Issued: 2002
Buffering strategies and bandwidth renegotiation for MPEG video streams
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
Interspecific interactions of the sea urchin Parechinus angulosus and the effect of variations in microhabitat availability
- Authors: Farquhar, Michael Robert
- Date: 1995
- Subjects: Sea urchins , Niche (Ecology) , Sea urchins -- Habitat
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5720 , http://hdl.handle.net/10962/d1005406 , Sea urchins , Niche (Ecology) , Sea urchins -- Habitat
- Description: Intertidal populations of the sea urchin Parechinus angulosus were examined at seven sites along the south and east coasts of South Africa. At the five southerly sites, P. angulosus occurred in allopatry, while, at the two northerly sites, it occurred in sympatry with several species of Indopacific sea urchins. At the five southerly sites, there was a significant correlation of number of sea urchins per pool with the surface area of the overhang in that pool. This relationship broke down for P. angulosus at the two northerly sites, where there was a significant correlation between these two factors for Stomopneustes variolaris. The density of populations of P. angulosus at the two northerly sites, although not significantly different from all five southerly sites, were considerably lower. There was a significant difference between the mean size of populations at the seven sites. Although no direct evidence is available, a competitive interaction between these two species is proposed to explain the observed patterns of microhabitat utilization and densities. Two series of manipulative experiments were conducted at Kowie Point, where P. angulosus occurs in sympatry, The first, involved urchin removals from three experimental sites. The percentage cover of four functional algal groups was monitored in three experimental and three unaltered control sites over a three month period in spring (Sept. - Dec.) 1993. Two 100 point 0,25m² random point quadrats were thrown at each of the six sites at approximately monthly intervals over the experimental period. Since initial cover of algae varied at the six sites, ANOVA's of the change in percentage cover of four functional algal groups were used to determine treatment effects. No treatment effects were identified for any of the four functional algal groups. There was a strong negative correlation between the percentage cover of foliose algae and encrusting coralline algae, suggesting the possibility of a competitive relationship between them. The second, involved the experimental manipulation of microhabitat availability. The blocking of overhangs, by means of cement filled bags, resulted in an approximate 50% decrease in the total number of urchins in the two experimental pools, and the two control pools without overhangs. However, in the control pool with overhangs there was a slight increase in the number of urchins over the same period. Clearly, the presence of suitable shelters, is a prerequisite for the maintenance of dense intertidal population of P. angulosus. It is proposed that, due to the exposed nature of the South African coast, intertidal populations of P.angulosus are restricted to inhabiting suitable shelters from which they emerge to feed on passing drift algae. The implications of these findings are discussed in terms of current ecological literature.
- Full Text:
- Date Issued: 1995
- Authors: Farquhar, Michael Robert
- Date: 1995
- Subjects: Sea urchins , Niche (Ecology) , Sea urchins -- Habitat
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5720 , http://hdl.handle.net/10962/d1005406 , Sea urchins , Niche (Ecology) , Sea urchins -- Habitat
- Description: Intertidal populations of the sea urchin Parechinus angulosus were examined at seven sites along the south and east coasts of South Africa. At the five southerly sites, P. angulosus occurred in allopatry, while, at the two northerly sites, it occurred in sympatry with several species of Indopacific sea urchins. At the five southerly sites, there was a significant correlation of number of sea urchins per pool with the surface area of the overhang in that pool. This relationship broke down for P. angulosus at the two northerly sites, where there was a significant correlation between these two factors for Stomopneustes variolaris. The density of populations of P. angulosus at the two northerly sites, although not significantly different from all five southerly sites, were considerably lower. There was a significant difference between the mean size of populations at the seven sites. Although no direct evidence is available, a competitive interaction between these two species is proposed to explain the observed patterns of microhabitat utilization and densities. Two series of manipulative experiments were conducted at Kowie Point, where P. angulosus occurs in sympatry, The first, involved urchin removals from three experimental sites. The percentage cover of four functional algal groups was monitored in three experimental and three unaltered control sites over a three month period in spring (Sept. - Dec.) 1993. Two 100 point 0,25m² random point quadrats were thrown at each of the six sites at approximately monthly intervals over the experimental period. Since initial cover of algae varied at the six sites, ANOVA's of the change in percentage cover of four functional algal groups were used to determine treatment effects. No treatment effects were identified for any of the four functional algal groups. There was a strong negative correlation between the percentage cover of foliose algae and encrusting coralline algae, suggesting the possibility of a competitive relationship between them. The second, involved the experimental manipulation of microhabitat availability. The blocking of overhangs, by means of cement filled bags, resulted in an approximate 50% decrease in the total number of urchins in the two experimental pools, and the two control pools without overhangs. However, in the control pool with overhangs there was a slight increase in the number of urchins over the same period. Clearly, the presence of suitable shelters, is a prerequisite for the maintenance of dense intertidal population of P. angulosus. It is proposed that, due to the exposed nature of the South African coast, intertidal populations of P.angulosus are restricted to inhabiting suitable shelters from which they emerge to feed on passing drift algae. The implications of these findings are discussed in terms of current ecological literature.
- Full Text:
- Date Issued: 1995
Funeral rites of the amaXhosa as therapeutic procedures compared to crisis intervention : an anthropological-descriptive evaluation
- Solomon, Angela Ntombizodwa Nokuphila
- Authors: Solomon, Angela Ntombizodwa Nokuphila
- Date: 1987
- Subjects: Xhosa (African people) -- Funeral customs and rites , Xhosa (African people) -- Psychology , Bereavement -- Psychological aspects , Mourning customs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3164 , http://hdl.handle.net/10962/d1007699
- Description: This study was undertaken in an attempt to investigate the analogy between the Crisis Intervention Model and the Funeral Rites of the amaXhosa. The latter group includes both traditional as well as Western Christian elements. The study was confined to the geographical area of Ciskei and more specifically the villages in and around Peddie and Ndevana near Zwelitsha, as regards traditional people, and the Black townships of Zwelitsha and Whittlesea,as regards more Westernized people. It is, however, the contention of the study that experiences discussed here are common to Blacks in South Africa irrespective of ethnicity. The justification for this generalisation is based on anthropological commonalities as well as historical vicissitudes among Blacks in Southern Africa. For instance, ritual slaughter performed after death in propitiation with the ancestors is known among all Blacks in South Africa. Also the Politico-historical events as well as socio-economic developments in the country affect Blacks in a more or less similar manner. For example, the changing family structure among Blacks, because of changes from one type of economy to another, is a social process affecting all Blacks in Southern Africa - in particular the working class (Colin Murray, 1980). The Funeral rites under study are postulated as possessing elements of therapeutic and practical value which result in the alleviation of grief and the encouragement of full acceptable means of mourning. The study is chiefly descriptive and anthropological material has been used. Recordings were made from participant observation whenever there was a funeral in the area studied. Information about funerals is easily obtainable as these are announced over Radio Ciskei and Radio Xhosa every evening. Mourners and interveners were interviewed. The former to elicit the needs they had felt, the latter to elicit the needs they had perceived the former to have. The Crisis Intervention Model is fairly simple to understand and uses practical theory. Therefore, it is not surprising that there should be elements of similarity between this model and the funeral rites of the amaXhosa as both deal with people in need of support. These funeral rites are rooted in a culture which has as one of its crucial aspects intimate, face-to-face interaction of its members in constant exchange as regards both emotional support and services. These "credit networks" ensure that a person is never bereft of emotional support. Moreover, temporary services are always accorded to a person in crisis. An effort has been made to relate the Crisis Intervention Model to the South African context of Blacks (both traditional as well as Christian). By necessity this has meant looking at all cultural dimensions of Black society - historical, political, economic and cultural, in order to provide a clearer picture of the people under study. That is, human psychological experiences of grief and mourning are seen as processes related to and developing within the concrete everyday realities. Some of the experiences described have been personally witnessed by the researcher in her personal involvement with cultural practices. Funerals are, of necessity, sad occasions and this study, using participant observation methods sometimes brought on sad memories of the researcher's own losses of loved ones. In the discussion a comparison was made between the traditional methods of grief work, the Crisis Intervention theory and the mourner studied and it was found that these rites do indeed, contain therapeutic and practical elements of dealing with grief and mourning, comparable to the Crisis Intervention Model. Finally in the conclusior a proposal for further areas of study in this field was suggested.
- Full Text:
- Date Issued: 1987
- Authors: Solomon, Angela Ntombizodwa Nokuphila
- Date: 1987
- Subjects: Xhosa (African people) -- Funeral customs and rites , Xhosa (African people) -- Psychology , Bereavement -- Psychological aspects , Mourning customs -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3164 , http://hdl.handle.net/10962/d1007699
- Description: This study was undertaken in an attempt to investigate the analogy between the Crisis Intervention Model and the Funeral Rites of the amaXhosa. The latter group includes both traditional as well as Western Christian elements. The study was confined to the geographical area of Ciskei and more specifically the villages in and around Peddie and Ndevana near Zwelitsha, as regards traditional people, and the Black townships of Zwelitsha and Whittlesea,as regards more Westernized people. It is, however, the contention of the study that experiences discussed here are common to Blacks in South Africa irrespective of ethnicity. The justification for this generalisation is based on anthropological commonalities as well as historical vicissitudes among Blacks in Southern Africa. For instance, ritual slaughter performed after death in propitiation with the ancestors is known among all Blacks in South Africa. Also the Politico-historical events as well as socio-economic developments in the country affect Blacks in a more or less similar manner. For example, the changing family structure among Blacks, because of changes from one type of economy to another, is a social process affecting all Blacks in Southern Africa - in particular the working class (Colin Murray, 1980). The Funeral rites under study are postulated as possessing elements of therapeutic and practical value which result in the alleviation of grief and the encouragement of full acceptable means of mourning. The study is chiefly descriptive and anthropological material has been used. Recordings were made from participant observation whenever there was a funeral in the area studied. Information about funerals is easily obtainable as these are announced over Radio Ciskei and Radio Xhosa every evening. Mourners and interveners were interviewed. The former to elicit the needs they had felt, the latter to elicit the needs they had perceived the former to have. The Crisis Intervention Model is fairly simple to understand and uses practical theory. Therefore, it is not surprising that there should be elements of similarity between this model and the funeral rites of the amaXhosa as both deal with people in need of support. These funeral rites are rooted in a culture which has as one of its crucial aspects intimate, face-to-face interaction of its members in constant exchange as regards both emotional support and services. These "credit networks" ensure that a person is never bereft of emotional support. Moreover, temporary services are always accorded to a person in crisis. An effort has been made to relate the Crisis Intervention Model to the South African context of Blacks (both traditional as well as Christian). By necessity this has meant looking at all cultural dimensions of Black society - historical, political, economic and cultural, in order to provide a clearer picture of the people under study. That is, human psychological experiences of grief and mourning are seen as processes related to and developing within the concrete everyday realities. Some of the experiences described have been personally witnessed by the researcher in her personal involvement with cultural practices. Funerals are, of necessity, sad occasions and this study, using participant observation methods sometimes brought on sad memories of the researcher's own losses of loved ones. In the discussion a comparison was made between the traditional methods of grief work, the Crisis Intervention theory and the mourner studied and it was found that these rites do indeed, contain therapeutic and practical elements of dealing with grief and mourning, comparable to the Crisis Intervention Model. Finally in the conclusior a proposal for further areas of study in this field was suggested.
- Full Text:
- Date Issued: 1987
The influence of ants on the insect fauna of broad-leaved, savanna trees
- Authors: Grant, Susan
- Date: 1985
- Subjects: Ants -- Behavior , Insects -- Host plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5811 , http://hdl.handle.net/10962/d1006971 , Ants -- Behavior , Insects -- Host plants
- Description: The influence of foraging ants on the insect fauna within the canopy of the tree species Terminalia sericea, Burkea africana and Ochna pulchra was studied in an area of typical South African savanna, over a two year period. The number of individual insects and their species composition was compared on unbanded, ant-infested plants and on banded plants where ants had been excluded. Differences in the level of herbivory recorded on banded and unbanded trees were related to the guild composition of insects within the canopy, and the results are discussed in terms of plant protection as a consequence of ant - insect interactions. Twenty-six ant species were recorded on the study trees at Nylsvley, with individuals belonging to the genus Crematogaster being numerically abundant and dominant within the canopy of each species of tree. These dominant ant species influenced the insect fauna by their strong dependence on honeydew, encouraging a build up in numbers of Homoptera on the branches and leaves of foraged trees, and supporting homopterous populations within the confines of their nest compartments . The exclusion of ants from trees led to fewer "mobile" homopterans (Aphididae, Membracidae, Psyllidae and Cicadellidae) and "sessile" homopterans (mainly Coccidae but also Pseudococcidae). Pyrethrum spraying showed that the guild composition of non-homopterous insects was similar on banded and unbanded trees. Differences in the level of herbivory on banded and unbanded trees suggested that, although slight, foraged trees were protected from some damage by the presence of ant species within the canopy. A trend did exist towards a greater number of insect individuals and species on unbanded trees, and it is postulated that during the period 1982 1984 when drought conditions prevailed over Nylsvley, ants do not reduce insect numbers through predation or disturbance but simply deter phyllophagous feeding. A separate experiment showed that Crematogaster constructor would feed on the eggs and early instar larvae of the saturnid moth, Cirina forda, but low numbers of lepidopterous larvae on the trees may have forced ants to seek honeydew. The negative impact of large homopterous populations on foraged trees was only seen in an isolated field observation where Polyrachis schistacea was found to associate with the lac insect Tachardina sp . . In conclusion it can be said that where homopterans are not the dominant phyllophages, plants do benefit from foraging populations of ants in that damage to the leaves is reduced.
- Full Text:
- Date Issued: 1985
- Authors: Grant, Susan
- Date: 1985
- Subjects: Ants -- Behavior , Insects -- Host plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5811 , http://hdl.handle.net/10962/d1006971 , Ants -- Behavior , Insects -- Host plants
- Description: The influence of foraging ants on the insect fauna within the canopy of the tree species Terminalia sericea, Burkea africana and Ochna pulchra was studied in an area of typical South African savanna, over a two year period. The number of individual insects and their species composition was compared on unbanded, ant-infested plants and on banded plants where ants had been excluded. Differences in the level of herbivory recorded on banded and unbanded trees were related to the guild composition of insects within the canopy, and the results are discussed in terms of plant protection as a consequence of ant - insect interactions. Twenty-six ant species were recorded on the study trees at Nylsvley, with individuals belonging to the genus Crematogaster being numerically abundant and dominant within the canopy of each species of tree. These dominant ant species influenced the insect fauna by their strong dependence on honeydew, encouraging a build up in numbers of Homoptera on the branches and leaves of foraged trees, and supporting homopterous populations within the confines of their nest compartments . The exclusion of ants from trees led to fewer "mobile" homopterans (Aphididae, Membracidae, Psyllidae and Cicadellidae) and "sessile" homopterans (mainly Coccidae but also Pseudococcidae). Pyrethrum spraying showed that the guild composition of non-homopterous insects was similar on banded and unbanded trees. Differences in the level of herbivory on banded and unbanded trees suggested that, although slight, foraged trees were protected from some damage by the presence of ant species within the canopy. A trend did exist towards a greater number of insect individuals and species on unbanded trees, and it is postulated that during the period 1982 1984 when drought conditions prevailed over Nylsvley, ants do not reduce insect numbers through predation or disturbance but simply deter phyllophagous feeding. A separate experiment showed that Crematogaster constructor would feed on the eggs and early instar larvae of the saturnid moth, Cirina forda, but low numbers of lepidopterous larvae on the trees may have forced ants to seek honeydew. The negative impact of large homopterous populations on foraged trees was only seen in an isolated field observation where Polyrachis schistacea was found to associate with the lac insect Tachardina sp . . In conclusion it can be said that where homopterans are not the dominant phyllophages, plants do benefit from foraging populations of ants in that damage to the leaves is reduced.
- Full Text:
- Date Issued: 1985
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