Some factors governing the water quality of microtidal estuaries in South Africa
- Authors: Allanson, Brian R
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7096 , http://hdl.handle.net/10962/d1012439
- Description: The role of coastal geomorphology and Man-made alterations, including reduced river flow through dam construction, determines, at least in part, the water quality of South African microtidal estuaries. To offer increased understanding of the manner in which these features may modify water quality, a short description of the biogeochemical processes in estuaries is provided. Comment on the present limitations of modelling some of the estuarine processes in South African investigations is given.
- Full Text:
- Date Issued: 2001
- Authors: Allanson, Brian R
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7096 , http://hdl.handle.net/10962/d1012439
- Description: The role of coastal geomorphology and Man-made alterations, including reduced river flow through dam construction, determines, at least in part, the water quality of South African microtidal estuaries. To offer increased understanding of the manner in which these features may modify water quality, a short description of the biogeochemical processes in estuaries is provided. Comment on the present limitations of modelling some of the estuarine processes in South African investigations is given.
- Full Text:
- Date Issued: 2001
Creating international support for the development of the news media in Africa
- Authors: Banda, Fackson
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6326 , http://hdl.handle.net/10962/d1008301
- Description: This article analyses the issues associated with providing support mechanisms for strengthening media institutions in Africa. It takes a historical look at the involvement of international actors in the evolution of African media, arguing that ideology plays a key role in the way international support is crafted for Africa's development, including media development.
- Full Text:
- Date Issued: 2006
- Authors: Banda, Fackson
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6326 , http://hdl.handle.net/10962/d1008301
- Description: This article analyses the issues associated with providing support mechanisms for strengthening media institutions in Africa. It takes a historical look at the involvement of international actors in the evolution of African media, arguing that ideology plays a key role in the way international support is crafted for Africa's development, including media development.
- Full Text:
- Date Issued: 2006
Bioremediation of trace organic compounds found in precious metals refineries wastewaters: A review of potential options
- Barbosa, V L, Tandlich, Roman, Burgess, Jo E
- Authors: Barbosa, V L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6469 , http://hdl.handle.net/10962/d1005798 , http://dx.doi.org/10.1016/j.chemosphere.2007.01.018 , http://www.sciencedirect.com/science/article/pii/S0045653507001026
- Description: Platinum group metal (PGM) refining processes produce large quantities of wastewater, which is contaminated with the compounds that make up the solvents/extractants mixtures used in the process. These compounds often include solvesso, β-hydroxyxime, amines, amides and methyl isobutyl ketone. A process to clean up PGM refinery wastewaters so that they could be re-used in the refining process would greatly contribute to continual water storage problems and to cost reduction for the industry. Based on the concept that organic compounds that are produced biologically can be destroyed biologically, the use of biological processes for the treatment of organic compounds in other types of waste stream has been favoured in recent years, owing to their low cost and environmental acceptability. This review examines the available biotechnologies and their effectiveness for treating compounds likely to be contained in precious metal extraction process wastewaters. The processes examined include: biofilters, fluidized bed reactors, trickle-bed bioreactors, bioscrubbers, two-phase partitioning bioreactors, membrane bioreactors and activated sludge. Although all processes examined showed adequate to excellent removal of organic compounds from various gaseous and fewer liquid waste streams, there was a variation in their effectiveness. Variations in performance of laboratory-scale biological processes are probably due to the inherent change in the microbial population composition due to selection pressure, environmental conditions and the time allowed for adaptation to the organic compounds. However, if these factors are disregarded, it can be established that activated sludge and membrane bioreactors are the most promising processes for use in the treatment of PGM refinery wastewaters.
- Full Text:
- Date Issued: 2007
- Authors: Barbosa, V L , Tandlich, Roman , Burgess, Jo E
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6469 , http://hdl.handle.net/10962/d1005798 , http://dx.doi.org/10.1016/j.chemosphere.2007.01.018 , http://www.sciencedirect.com/science/article/pii/S0045653507001026
- Description: Platinum group metal (PGM) refining processes produce large quantities of wastewater, which is contaminated with the compounds that make up the solvents/extractants mixtures used in the process. These compounds often include solvesso, β-hydroxyxime, amines, amides and methyl isobutyl ketone. A process to clean up PGM refinery wastewaters so that they could be re-used in the refining process would greatly contribute to continual water storage problems and to cost reduction for the industry. Based on the concept that organic compounds that are produced biologically can be destroyed biologically, the use of biological processes for the treatment of organic compounds in other types of waste stream has been favoured in recent years, owing to their low cost and environmental acceptability. This review examines the available biotechnologies and their effectiveness for treating compounds likely to be contained in precious metal extraction process wastewaters. The processes examined include: biofilters, fluidized bed reactors, trickle-bed bioreactors, bioscrubbers, two-phase partitioning bioreactors, membrane bioreactors and activated sludge. Although all processes examined showed adequate to excellent removal of organic compounds from various gaseous and fewer liquid waste streams, there was a variation in their effectiveness. Variations in performance of laboratory-scale biological processes are probably due to the inherent change in the microbial population composition due to selection pressure, environmental conditions and the time allowed for adaptation to the organic compounds. However, if these factors are disregarded, it can be established that activated sludge and membrane bioreactors are the most promising processes for use in the treatment of PGM refinery wastewaters.
- Full Text:
- Date Issued: 2007
The effect of prolonged cold storage of eland (Taurotragus oryx) cauda epididymides on the spermatozoa: possible implications for the conservation of biodiversity
- Bissett, Charlene, Bernard, Ric T F
- Authors: Bissett, Charlene , Bernard, Ric T F
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6947 , http://hdl.handle.net/10962/d1011976
- Description: The objectives of this study were to investigate the effects of prolonged storage of cauda epididymides at 4 °C on spermatozoa, and to determine the practicality of utilising epididymal sperm, harvested from testes collected during routine culling of game animals, in assisted reproductive technologies. Testes from eland (Taurotragus oryx) were collected and epididymides removed and maintained at 4 °C. Sperm motility, viability, morphology and membrane integrity were examined at 12 h intervals for 108 h. Sperm motility and viability were significantly lower at the end of the experiment than at the start (P < 0.05) and there was individual variation in the rate at which motility and viability declined. The total number of normal sperm decreased significantly with prolonged storage at 4 °C. Midpiece defects were the most common and head and tail abnormalities were rare. A significant decrease in acrosomal and nuclear membrane integrity was observed with prolonged cold storage but there was no significant change in cell membrane integrity. However, about 30% of epididymal sperm survived for 3 days at 4 °C and more than 10% survived for 4 days, and it should be possible to use sperm from culled animals in some assisted reproductive technologies.
- Full Text:
- Date Issued: 2005
- Authors: Bissett, Charlene , Bernard, Ric T F
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6947 , http://hdl.handle.net/10962/d1011976
- Description: The objectives of this study were to investigate the effects of prolonged storage of cauda epididymides at 4 °C on spermatozoa, and to determine the practicality of utilising epididymal sperm, harvested from testes collected during routine culling of game animals, in assisted reproductive technologies. Testes from eland (Taurotragus oryx) were collected and epididymides removed and maintained at 4 °C. Sperm motility, viability, morphology and membrane integrity were examined at 12 h intervals for 108 h. Sperm motility and viability were significantly lower at the end of the experiment than at the start (P < 0.05) and there was individual variation in the rate at which motility and viability declined. The total number of normal sperm decreased significantly with prolonged storage at 4 °C. Midpiece defects were the most common and head and tail abnormalities were rare. A significant decrease in acrosomal and nuclear membrane integrity was observed with prolonged cold storage but there was no significant change in cell membrane integrity. However, about 30% of epididymal sperm survived for 3 days at 4 °C and more than 10% survived for 4 days, and it should be possible to use sperm from culled animals in some assisted reproductive technologies.
- Full Text:
- Date Issued: 2005
Texts, practices and student learning: a view from the South
- Authors: Boughey, Chrissie
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6085 , http://hdl.handle.net/10962/d1008482
- Description: This article uses ‘close-up’ ethnographic research to provide an account of students’ engagement with learning in a South African university. Broadly based on Halliday’s (1973, 1978, 1994) understanding of texts resulting from contexts, the account challenges dominant constructions of the problems students encounter as stemming from the use of inappropriate ‘approaches’ to learning, the lack of ‘study’ and other skills or problems with proficiency in areas such as writing or language and shows how students’ unfamiliarity with the context of the university leads them to draw on ‘other’ contexts in order to engage with the texts they must read, write and listen to in the course of their studies. This drawing on ‘other’ contexts then results in the texts produced by students, and the practices which give rise to those texts, being inappropriate to the context of the university. Although the research on which the article is based took place in South Africa, it is argued that the theoretical perspective it provides has relevance across other contexts given the increasingly diverse student bodies which characterize higher education across the globe.
- Full Text:
- Date Issued: 2008
- Authors: Boughey, Chrissie
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6085 , http://hdl.handle.net/10962/d1008482
- Description: This article uses ‘close-up’ ethnographic research to provide an account of students’ engagement with learning in a South African university. Broadly based on Halliday’s (1973, 1978, 1994) understanding of texts resulting from contexts, the account challenges dominant constructions of the problems students encounter as stemming from the use of inappropriate ‘approaches’ to learning, the lack of ‘study’ and other skills or problems with proficiency in areas such as writing or language and shows how students’ unfamiliarity with the context of the university leads them to draw on ‘other’ contexts in order to engage with the texts they must read, write and listen to in the course of their studies. This drawing on ‘other’ contexts then results in the texts produced by students, and the practices which give rise to those texts, being inappropriate to the context of the university. Although the research on which the article is based took place in South Africa, it is argued that the theoretical perspective it provides has relevance across other contexts given the increasingly diverse student bodies which characterize higher education across the globe.
- Full Text:
- Date Issued: 2008
Will the invasive mussel Mytilus galloprovincialis Lamarck replace the indigenous Perna perna L. on the south coast of South Africa?
- Bownes, Sarah J, McQuaid, Christopher D
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6926 , http://hdl.handle.net/10962/d1011914
- Description: The mussel Mytilus galloprovincialis is invasive worldwide, has displaced indigenous species on the west coast of South Africa and now threatens Perna perna on the south coast. We tested the hypothesis that Mytilus will replace Perna by examining changes in their distribution on shores where they co-exist. Total cover, adult density, recruit density, recruit/adult correlations and mean maximum lengths of both species were measured in 2001 at two contrasting sites (Plettenberg Bay and Tsitsikamma) 70 km apart, each including two locations 100 m apart. Cover and density were measured again in 2004. Total mussel abundance was significantly lower in Tsitsikamma, and recruit density was only 17% that of Plettenberg Bay. Abundance and cover increased upshore for Mytilus, but decreased for Perna, giving Mytilus higher adult and recruit density and total cover than Perna in the upper zones. Low shore densities of recruits and adults were similar between species but cover was lower for Mytilus, reflecting its smaller size, and presumably slower growth or higher mortality there. Thus, mechanisms excluding species differed among zones. Recruitment limitation delays invasion at Tsitsikamma and excludes Perna from the high shore, while Mytilus is excluded from the low shore by post-recruitment effects. Recruitment limitation also shapes population structure. Recruit/adult correlations were significant only where adult densities were low, and this effect was species-specific. Thus, at low densities, larvae settle or survive better near adult conspecifics. After 3 years, these patterns remained strongly evident, suggesting Mytilus will not eliminate Perna and that co-existence is possible through partial habitat segregation driven by recruitment limitation of Perna on the high shore and post-settlement effects on Mytilus on the low shore.
- Full Text:
- Date Issued: 2006
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6926 , http://hdl.handle.net/10962/d1011914
- Description: The mussel Mytilus galloprovincialis is invasive worldwide, has displaced indigenous species on the west coast of South Africa and now threatens Perna perna on the south coast. We tested the hypothesis that Mytilus will replace Perna by examining changes in their distribution on shores where they co-exist. Total cover, adult density, recruit density, recruit/adult correlations and mean maximum lengths of both species were measured in 2001 at two contrasting sites (Plettenberg Bay and Tsitsikamma) 70 km apart, each including two locations 100 m apart. Cover and density were measured again in 2004. Total mussel abundance was significantly lower in Tsitsikamma, and recruit density was only 17% that of Plettenberg Bay. Abundance and cover increased upshore for Mytilus, but decreased for Perna, giving Mytilus higher adult and recruit density and total cover than Perna in the upper zones. Low shore densities of recruits and adults were similar between species but cover was lower for Mytilus, reflecting its smaller size, and presumably slower growth or higher mortality there. Thus, mechanisms excluding species differed among zones. Recruitment limitation delays invasion at Tsitsikamma and excludes Perna from the high shore, while Mytilus is excluded from the low shore by post-recruitment effects. Recruitment limitation also shapes population structure. Recruit/adult correlations were significant only where adult densities were low, and this effect was species-specific. Thus, at low densities, larvae settle or survive better near adult conspecifics. After 3 years, these patterns remained strongly evident, suggesting Mytilus will not eliminate Perna and that co-existence is possible through partial habitat segregation driven by recruitment limitation of Perna on the high shore and post-settlement effects on Mytilus on the low shore.
- Full Text:
- Date Issued: 2006
Mental illness and the consciousness of freedom: the phenomenology of psychiatric labelling
- Authors: Bradfield, Bruce
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6264 , http://hdl.handle.net/10962/d1007882
- Description: Paradigmatically led by existential phenomenological premises, as formulated by Jean-Paul Sartre and Edmund Husserl specifically, this paper aims at a deconstruction of the value of psychiatric labelling in terms of the implications of such labelling for the labelled individual's experience of freedom as a conscious imperative. This work has as its intention the destabilisation of labelling as a stubborn and inexorable mechanism for social propriety and regularity, which in its unyielding classificatory brandings is.
- Full Text:
- Date Issued: 2002
- Authors: Bradfield, Bruce
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6264 , http://hdl.handle.net/10962/d1007882
- Description: Paradigmatically led by existential phenomenological premises, as formulated by Jean-Paul Sartre and Edmund Husserl specifically, this paper aims at a deconstruction of the value of psychiatric labelling in terms of the implications of such labelling for the labelled individual's experience of freedom as a conscious imperative. This work has as its intention the destabilisation of labelling as a stubborn and inexorable mechanism for social propriety and regularity, which in its unyielding classificatory brandings is.
- Full Text:
- Date Issued: 2002
The role of ‘African Chemists’ in the health care system of the Eastern Cape province of South Africa
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:7105 , http://hdl.handle.net/10962/d1010675
- Description: Self-medication is documented as an integral part of health care therapy in developing countries such as Ethiopia, Cameroon, Uganda and Mexico. In South Africa the types of illnesses and health problems that are referred to both traditional healers and biomedical practices have been well documented. However, very little literature exists on self-diagnosis, self-medication or sources of the medicines used for self-medication. This bias in the literature has come about largely because anthropological studies have focused on the later stages of the illness referral system when treatment is sought from a specialist for symptoms which have not responded to forms of self-medication. As a result of this, health care studies have documented the more exceptional exotic healing rituals and culturally bound syndromes of a particular society or community, and not discussed the more ordinary practices of self-medication of everyday illness. Self-medication is however an important initial response to illness and many illnesses are successfully managed at this stage. Amayeza stores (singular-iyeza store) — or ‘African chemists’ — are an important source of medicines for self-diagnosed illnesses. The current discussion focuses on the types of medicines and treatments that are obtained from amayeza stores without professional consultation in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2000
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:7105 , http://hdl.handle.net/10962/d1010675
- Description: Self-medication is documented as an integral part of health care therapy in developing countries such as Ethiopia, Cameroon, Uganda and Mexico. In South Africa the types of illnesses and health problems that are referred to both traditional healers and biomedical practices have been well documented. However, very little literature exists on self-diagnosis, self-medication or sources of the medicines used for self-medication. This bias in the literature has come about largely because anthropological studies have focused on the later stages of the illness referral system when treatment is sought from a specialist for symptoms which have not responded to forms of self-medication. As a result of this, health care studies have documented the more exceptional exotic healing rituals and culturally bound syndromes of a particular society or community, and not discussed the more ordinary practices of self-medication of everyday illness. Self-medication is however an important initial response to illness and many illnesses are successfully managed at this stage. Amayeza stores (singular-iyeza store) — or ‘African chemists’ — are an important source of medicines for self-diagnosed illnesses. The current discussion focuses on the types of medicines and treatments that are obtained from amayeza stores without professional consultation in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2000
The role of 'African Chemists' in the health care system of the Eastern Cape province of South Africa
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6508 , http://hdl.handle.net/10962/d1005935
- Description: Self-medication is documented as an integral part of health care therapy in developing countries such as Ethiopia, Cameroon, Uganda and Mexico. In South Africa the types of illnesses and health problems that are referred to both traditional healers and biomedical practices have been well documented. However, very little literature exists on self-diagnosis, self-medication or sources of the medicines used for self-medication. This bias in the literature has come about largely because anthropological studies have focused on the later stages of the illness referral system when treatment is sought from a specialist for symptoms which have not responded to forms of self-medication. As a result of this, health care studies have documented the more exceptional exotic healing rituals and culturally bound syndromes of a particular society or community, and not discussed the more ordinary practices of self-medication of everyday illness. Self-medication is however an important initial response to illness and many illnesses are successfully managed at this stage. Amayeza stores (singular-iyeza store) — or ‘African chemists’ — are an important source of medicines for self-diagnosed illnesses. The current discussion focuses on the types of medicines and treatments that are obtained from amayeza stores without professional consultation in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2000
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6508 , http://hdl.handle.net/10962/d1005935
- Description: Self-medication is documented as an integral part of health care therapy in developing countries such as Ethiopia, Cameroon, Uganda and Mexico. In South Africa the types of illnesses and health problems that are referred to both traditional healers and biomedical practices have been well documented. However, very little literature exists on self-diagnosis, self-medication or sources of the medicines used for self-medication. This bias in the literature has come about largely because anthropological studies have focused on the later stages of the illness referral system when treatment is sought from a specialist for symptoms which have not responded to forms of self-medication. As a result of this, health care studies have documented the more exceptional exotic healing rituals and culturally bound syndromes of a particular society or community, and not discussed the more ordinary practices of self-medication of everyday illness. Self-medication is however an important initial response to illness and many illnesses are successfully managed at this stage. Amayeza stores (singular-iyeza store) — or ‘African chemists’ — are an important source of medicines for self-diagnosed illnesses. The current discussion focuses on the types of medicines and treatments that are obtained from amayeza stores without professional consultation in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2000
Impact of nutrients and herbivory by Eccritotarsus catarinensis on the biological control of water hyacinth, Eichhornia crassipes
- Coetzee, Julie A, Byrne, Marcus J, Hill, Martin P
- Authors: Coetzee, Julie A , Byrne, Marcus J , Hill, Martin P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6945 , http://hdl.handle.net/10962/d1011973 , https://orcid.org/0000-0003-0579-5298
- Description: Many water hyacinth infestations in South Africa are the symptom of eutrophication, and as a result, biological control of this weed is variable. This study examined the effects of herbivory by the mirid, Eccritotarsus catarinensis, on water hyacinth grown at high, medium and low nitrogen (N) and phosphorus (P) nutrient concentrations. Water nutrient concentration appears to be the overriding factor affecting plant growth parameters of water hyacinth plants—at high nutrient concentrations, leaf and daughter plant production were more than double than at low nutrient concentrations, while stem length was twice as great at high nutrient concentrations compared to low concentrations. Chlorophyll content was also twice as high at high nutrient concentrations than low concentrations. Conversely, flower production at high nutrient concentrations was less than half that at low concentrations. Herbivory by E. catarinensis did not have as great an effect on water hyacinth vigour as nutrient concentration did, although it significantly reduced the production of daughter plants by 23 ± 9%, the length of the second petiole by 13 ± 5%, and chlorophyll content of water hyacinth leaves by 15 ± 6%. In terms of insect numbers, mirids performed better on plants grown under medium nutrient conditions (99 ± 28 S.E.), compared to high nutrient concentrations (52 ± 27 S.E.), and low nutrient concentrations (25 ± 30 S.E.). Thus, these results suggest that the fastest and most significant reduction in water hyacinth proliferation would be reached by lowering the water nutrient concentrations, and herbivory by E. catarinensis alone is not sufficient to reduce all aspects of water hyacinth vigour, especially at very high nutrient concentrations.
- Full Text:
- Date Issued: 2007
- Authors: Coetzee, Julie A , Byrne, Marcus J , Hill, Martin P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6945 , http://hdl.handle.net/10962/d1011973 , https://orcid.org/0000-0003-0579-5298
- Description: Many water hyacinth infestations in South Africa are the symptom of eutrophication, and as a result, biological control of this weed is variable. This study examined the effects of herbivory by the mirid, Eccritotarsus catarinensis, on water hyacinth grown at high, medium and low nitrogen (N) and phosphorus (P) nutrient concentrations. Water nutrient concentration appears to be the overriding factor affecting plant growth parameters of water hyacinth plants—at high nutrient concentrations, leaf and daughter plant production were more than double than at low nutrient concentrations, while stem length was twice as great at high nutrient concentrations compared to low concentrations. Chlorophyll content was also twice as high at high nutrient concentrations than low concentrations. Conversely, flower production at high nutrient concentrations was less than half that at low concentrations. Herbivory by E. catarinensis did not have as great an effect on water hyacinth vigour as nutrient concentration did, although it significantly reduced the production of daughter plants by 23 ± 9%, the length of the second petiole by 13 ± 5%, and chlorophyll content of water hyacinth leaves by 15 ± 6%. In terms of insect numbers, mirids performed better on plants grown under medium nutrient conditions (99 ± 28 S.E.), compared to high nutrient concentrations (52 ± 27 S.E.), and low nutrient concentrations (25 ± 30 S.E.). Thus, these results suggest that the fastest and most significant reduction in water hyacinth proliferation would be reached by lowering the water nutrient concentrations, and herbivory by E. catarinensis alone is not sufficient to reduce all aspects of water hyacinth vigour, especially at very high nutrient concentrations.
- Full Text:
- Date Issued: 2007
The invasive ‘mothcatcher’ (Araujia sericifera Brot.; Asclepiadoideae) co-opts native honeybees as its primary pollinator in South Africa
- Coombs, Gareth, Peter, Craig I
- Authors: Coombs, Gareth , Peter, Craig I
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6510 , http://hdl.handle.net/10962/d1005937
- Description: Background and aims: Successful invasive plants such as Araujia sericifera usually either are capable of automatic self-pollination or maintain pollinator services by having generalized pollination systems to make use of local pollinators in the invaded range. Alternatively, plants must co-opt new pollinators with similar morphology to native pollinators or reproduce asexually. We aimed to document the pollination biology of A. sericifera in South Africa. Given the success of this species as an invader, we predicted that sexual reproduction occurs either through self-pollination or because A. sericifera has successfully co-opted native insect pollinators. Methodology: We examined the pollination biology of the South American A. sericifera in South Africa. We documented the effective pollinators including a comparison of the efficacy of nocturnal versus diurnal pollinators as well as the breeding system and long-term natural levels of the pollination success of this species. Principal results: We found that native honeybees (Apis mellifera) were the main pollinators of A. sericifera in South Africa. Visiting moths are unimportant pollinators despite being attracted by the pale colour and nocturnal scent of the flowers. Plants from the Grahamstown population were incapable of autonomous self-pollination but pollinator-mediated self-pollination does occur. However, the highest fruit initiation resulted from out-crossed pollination treatments. The high pollen transfer efficiency of this species was comparable to other hymenopteranpollinated exotic and native milkweeds, suggesting that A. sericifera maintains pollinator services at levels experienced by indigenous asclepiad species. Conclusions: Araujia sericifera reproduces successfully in South Africa due to a combined ability of this species to attract and exploit native honeybees as its pollinators and of individual plants to set fruit from pollinator-mediated self-pollination.
- Full Text:
- Date Issued: 2010
- Authors: Coombs, Gareth , Peter, Craig I
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6510 , http://hdl.handle.net/10962/d1005937
- Description: Background and aims: Successful invasive plants such as Araujia sericifera usually either are capable of automatic self-pollination or maintain pollinator services by having generalized pollination systems to make use of local pollinators in the invaded range. Alternatively, plants must co-opt new pollinators with similar morphology to native pollinators or reproduce asexually. We aimed to document the pollination biology of A. sericifera in South Africa. Given the success of this species as an invader, we predicted that sexual reproduction occurs either through self-pollination or because A. sericifera has successfully co-opted native insect pollinators. Methodology: We examined the pollination biology of the South American A. sericifera in South Africa. We documented the effective pollinators including a comparison of the efficacy of nocturnal versus diurnal pollinators as well as the breeding system and long-term natural levels of the pollination success of this species. Principal results: We found that native honeybees (Apis mellifera) were the main pollinators of A. sericifera in South Africa. Visiting moths are unimportant pollinators despite being attracted by the pale colour and nocturnal scent of the flowers. Plants from the Grahamstown population were incapable of autonomous self-pollination but pollinator-mediated self-pollination does occur. However, the highest fruit initiation resulted from out-crossed pollination treatments. The high pollen transfer efficiency of this species was comparable to other hymenopteranpollinated exotic and native milkweeds, suggesting that A. sericifera maintains pollinator services at levels experienced by indigenous asclepiad species. Conclusions: Araujia sericifera reproduces successfully in South Africa due to a combined ability of this species to attract and exploit native honeybees as its pollinators and of individual plants to set fruit from pollinator-mediated self-pollination.
- Full Text:
- Date Issued: 2010
The use of actually in spoken Xhosa English : a corpus study
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6136 , http://hdl.handle.net/10962/d1011588
- Description: The aim of this paper is to provide an overview of the semantic and syntactic characteristics of the discourse marker actually, and then to describe and explain how it is used by mothertongue (MT) Xhosa speakers who have learned English as an additional language. Such a description may provide a useful benchmark for comparison with MT norms. The source of data for the study is a corpus of approximately half a million words of transcribed spontaneous dialogue between Xhosa English speakers.
- Full Text:
- Date Issued: 2005
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6136 , http://hdl.handle.net/10962/d1011588
- Description: The aim of this paper is to provide an overview of the semantic and syntactic characteristics of the discourse marker actually, and then to describe and explain how it is used by mothertongue (MT) Xhosa speakers who have learned English as an additional language. Such a description may provide a useful benchmark for comparison with MT norms. The source of data for the study is a corpus of approximately half a million words of transcribed spontaneous dialogue between Xhosa English speakers.
- Full Text:
- Date Issued: 2005
How taboo are taboo words for girls?
- Authors: De Klerk, Vivian A
- Date: 1992
- Language: English
- Type: Article
- Identifier: vital:6143 , http://hdl.handle.net/10962/d1011596
- Description: In the past five years, there has been much interest in the question of whether women are really as concerned about politeness and status as they have been made out to be by such writers as Baroni and D'Urso (1984), Crosby and Nyquist (1977), Lakoff (1973), Spender (1980), and Trudgill (1972). Despite the commonly held perception that it is only males who bandy about derogatory and taboo words (Bailey 1985; Flexner 1975), Risch (1987) provided counterevidence based on data obtained in the United States. The results of the present study, based on data obtained in South Africa, strongly support her findings and challenge the assumption that women stick to standard speech, citing evidence that young females are familiar with, and use, a wide range of highly taboo/slang items themselves. In particular, attention is devoted to the question of pejorative words applicable to males and females, respectively, and the view that there are only a few pejorative terms commonly used to describe males (particularly by females) is challenged. (Women's language, politeness, linguistic taboo, stereotypes, slang, expletives, prestige forms).
- Full Text:
- Date Issued: 1992
- Authors: De Klerk, Vivian A
- Date: 1992
- Language: English
- Type: Article
- Identifier: vital:6143 , http://hdl.handle.net/10962/d1011596
- Description: In the past five years, there has been much interest in the question of whether women are really as concerned about politeness and status as they have been made out to be by such writers as Baroni and D'Urso (1984), Crosby and Nyquist (1977), Lakoff (1973), Spender (1980), and Trudgill (1972). Despite the commonly held perception that it is only males who bandy about derogatory and taboo words (Bailey 1985; Flexner 1975), Risch (1987) provided counterevidence based on data obtained in the United States. The results of the present study, based on data obtained in South Africa, strongly support her findings and challenge the assumption that women stick to standard speech, citing evidence that young females are familiar with, and use, a wide range of highly taboo/slang items themselves. In particular, attention is devoted to the question of pejorative words applicable to males and females, respectively, and the view that there are only a few pejorative terms commonly used to describe males (particularly by females) is challenged. (Women's language, politeness, linguistic taboo, stereotypes, slang, expletives, prestige forms).
- Full Text:
- Date Issued: 1992
The potential for voluntary instruments to achieve conservation planning goals : the case of conservancies in South Africa
- Downsborough, Linda, Shackleton, Charlie M, Knight, Andrew T
- Authors: Downsborough, Linda , Shackleton, Charlie M , Knight, Andrew T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6629 , http://hdl.handle.net/10962/d1006821
- Description: Spatial prioritizations and gap analyses are increasingly undertaken to allocate conservation resources. Most spatial prioritizations are conducted without specifying the conservation instruments to be implemented and gap analyses typically assess formally protected areas but increasingly include private land conservation instruments. We examine conservancies to see if these voluntary instruments contribute towards achieving goals of South African conservation planning initiatives. We conducted a nationwide survey and interviews with conservancy members in Gauteng and the Eastern Cape. Conservancies have potential for assisting South Africa to achieve conservation planning goals at national and local scales but their inclusion in spatial prioritizations and gap analyses predicates improved protection for nature, operational refinement and increased support. We sound a warning to conservation planning initiatives that incorporate voluntary instruments on private land, and present recommendations for strengthening such instruments to make them more effective. Our findings may assist conservation planners elsewhere to design more effective conservation planning initiatives focused on private land.
- Full Text:
- Date Issued: 2011
- Authors: Downsborough, Linda , Shackleton, Charlie M , Knight, Andrew T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6629 , http://hdl.handle.net/10962/d1006821
- Description: Spatial prioritizations and gap analyses are increasingly undertaken to allocate conservation resources. Most spatial prioritizations are conducted without specifying the conservation instruments to be implemented and gap analyses typically assess formally protected areas but increasingly include private land conservation instruments. We examine conservancies to see if these voluntary instruments contribute towards achieving goals of South African conservation planning initiatives. We conducted a nationwide survey and interviews with conservancy members in Gauteng and the Eastern Cape. Conservancies have potential for assisting South Africa to achieve conservation planning goals at national and local scales but their inclusion in spatial prioritizations and gap analyses predicates improved protection for nature, operational refinement and increased support. We sound a warning to conservation planning initiatives that incorporate voluntary instruments on private land, and present recommendations for strengthening such instruments to make them more effective. Our findings may assist conservation planners elsewhere to design more effective conservation planning initiatives focused on private land.
- Full Text:
- Date Issued: 2011
A Trypanosoma cruzi heat shock protein 40 is able to stimulate the adenosine triphosphate hydrolysis activity of heat shock protein 70 and can substitute for a yeast heat shock protein 40
- Edkins, Adrienne L, Ludewig, M H, Blatch, Gregory L
- Authors: Edkins, Adrienne L , Ludewig, M H , Blatch, Gregory L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6465 , http://hdl.handle.net/10962/d1005794 , http://dx.doi.org/10.1016/j.biocel.2004.01.016
- Description: The process of assisted protein folding, characteristic of members of the heat shock protein 70 (Hsp70) and heat shock protein 40 (Hsp40) molecular chaperone families, is important for maintaining the structural integrity of cellular protein machinery under normal and stressful conditions. Hsp70 and Hsp40 cooperate to bind non-native protein conformations in a process of adenosine triphosphate (ATP)-regulated assisted protein folding. We have analysed the molecular chaperone activity of the cytoplasmic inducible Hsp70 from Trypanosoma cruzi (TcHsp70) and its interactions with its potential partner Hsp40s (T. cruzi DnaJ protein 1 [Tcj1] and T. cruzi DnaJ protein 2 [Tcj2]). Histidine-tagged TcHsp70 (His-TcHsp70), Tcj1 (Tcj1-His) and Tcj2 (His-Tcj2) were over-produced in Escherichia coli and purified by nickel affinity chromatography. The in vitro basal specific ATP hydrolysis activity (ATPase activity) of His-TcHsp70 was determined as 40 nmol phosphate/min/mg protein, significantly higher than that reported for other Hsp70s. The basal specific ATPase activity was stimulated to a maximal level of 60 nmol phosphate/min/mg protein in the presence of His-Tcj2 and a model substrate, reduced carboxymethylated α-lactalbumin. In vivo complementation assays showed that Tcj2 was able to overcome the temperature sensitivity of the ydj1 mutant Saccharomyces cerevisiae strain JJ160, suggesting that Tcj2 may be functionally equivalent to the yeast Hsp40 homologue (yeast DnaJ protein 1, Ydj1). These data suggest that Tcj2 is involved in cytoprotection in a similar fashion to Ydj1, and that TcHsp70 and Tcj2 may interact in a nucleotide-regulated process of chaperone-assisted protein folding.
- Full Text:
- Date Issued: 2004
- Authors: Edkins, Adrienne L , Ludewig, M H , Blatch, Gregory L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6465 , http://hdl.handle.net/10962/d1005794 , http://dx.doi.org/10.1016/j.biocel.2004.01.016
- Description: The process of assisted protein folding, characteristic of members of the heat shock protein 70 (Hsp70) and heat shock protein 40 (Hsp40) molecular chaperone families, is important for maintaining the structural integrity of cellular protein machinery under normal and stressful conditions. Hsp70 and Hsp40 cooperate to bind non-native protein conformations in a process of adenosine triphosphate (ATP)-regulated assisted protein folding. We have analysed the molecular chaperone activity of the cytoplasmic inducible Hsp70 from Trypanosoma cruzi (TcHsp70) and its interactions with its potential partner Hsp40s (T. cruzi DnaJ protein 1 [Tcj1] and T. cruzi DnaJ protein 2 [Tcj2]). Histidine-tagged TcHsp70 (His-TcHsp70), Tcj1 (Tcj1-His) and Tcj2 (His-Tcj2) were over-produced in Escherichia coli and purified by nickel affinity chromatography. The in vitro basal specific ATP hydrolysis activity (ATPase activity) of His-TcHsp70 was determined as 40 nmol phosphate/min/mg protein, significantly higher than that reported for other Hsp70s. The basal specific ATPase activity was stimulated to a maximal level of 60 nmol phosphate/min/mg protein in the presence of His-Tcj2 and a model substrate, reduced carboxymethylated α-lactalbumin. In vivo complementation assays showed that Tcj2 was able to overcome the temperature sensitivity of the ydj1 mutant Saccharomyces cerevisiae strain JJ160, suggesting that Tcj2 may be functionally equivalent to the yeast Hsp40 homologue (yeast DnaJ protein 1, Ydj1). These data suggest that Tcj2 is involved in cytoprotection in a similar fashion to Ydj1, and that TcHsp70 and Tcj2 may interact in a nucleotide-regulated process of chaperone-assisted protein folding.
- Full Text:
- Date Issued: 2004
Mythic and theoretic aspects of the concept of 'the unconscious' in popular and psychological discourse
- Authors: Edwards, D J A
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6227 , http://hdl.handle.net/10962/d1007777
- Description: From the introduction: In Greek mythology, Typhon was the youngest son of Gaea (the Earth) and Tartarus (the underworld). Typhon was not a beautiful baby. He was a grisly monster with a hundred dragons' heads. He was one of the Titans, a group of powerful and dangerous creatures who rebelled against Zeus, the King of the Gods. The rebellion was crushed and Typhon was imprisoned under Mount Etna, the volcano in Sicily which was active in classical times and remains active today. It was said that when Typhon raged, the earth shook and Etna erupted. Many such tales from mythology from all over world seem to dramatize aspects of our relationship with potent forces of which we have little understanding and over which we have little control. Many of these forces are less concrete than the forces of nature. They arise from our apprehension of our existential predicaments, our interpersonal vulnerability and the intensity of our own psychological pain. In many contemporary discourses this territory is referred to more neutrally as ‘the unconscious;’ but the unconscious will always elude our attempts to capture it in words.
- Full Text:
- Date Issued: 2003
- Authors: Edwards, D J A
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6227 , http://hdl.handle.net/10962/d1007777
- Description: From the introduction: In Greek mythology, Typhon was the youngest son of Gaea (the Earth) and Tartarus (the underworld). Typhon was not a beautiful baby. He was a grisly monster with a hundred dragons' heads. He was one of the Titans, a group of powerful and dangerous creatures who rebelled against Zeus, the King of the Gods. The rebellion was crushed and Typhon was imprisoned under Mount Etna, the volcano in Sicily which was active in classical times and remains active today. It was said that when Typhon raged, the earth shook and Etna erupted. Many such tales from mythology from all over world seem to dramatize aspects of our relationship with potent forces of which we have little understanding and over which we have little control. Many of these forces are less concrete than the forces of nature. They arise from our apprehension of our existential predicaments, our interpersonal vulnerability and the intensity of our own psychological pain. In many contemporary discourses this territory is referred to more neutrally as ‘the unconscious;’ but the unconscious will always elude our attempts to capture it in words.
- Full Text:
- Date Issued: 2003
From panic disorder to complex traumatic stress disorder : retrospective reflections on the case of Tariq
- Authors: Edwards, David J A
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6234 , http://hdl.handle.net/10962/d1007784
- Description: This is a phenomenological-hermeneutic case study of Tariq who initially presented with panic disorder. It documents how, as therapy proceeded, the underlying meaning of his initial panic deepened as its roots in traumatic memories of childhood emerged. There were four spaced phases of treatment over four years. The first focused on anxiety management; the second was conceptualized within schema-focused therapy, and evoked and worked with childhood memories using inner child guided imagery; in the third and fourth phases insights gained led to an authentic re-engagement with family members in relationships that had been problematic. The panic attacks resolved and there were two dreams representing a reconfiguring of his relationship with his deceased father. The first two phases were the focus of an unpublished case study presented at a conference in 1995. This article incorporates material from that study and looks back at the case both in light of developments in phases two and three and also in light of theoretical developments in our understanding of complex trauma since the initial presentation.
- Full Text:
- Date Issued: 2013
- Authors: Edwards, David J A
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6234 , http://hdl.handle.net/10962/d1007784
- Description: This is a phenomenological-hermeneutic case study of Tariq who initially presented with panic disorder. It documents how, as therapy proceeded, the underlying meaning of his initial panic deepened as its roots in traumatic memories of childhood emerged. There were four spaced phases of treatment over four years. The first focused on anxiety management; the second was conceptualized within schema-focused therapy, and evoked and worked with childhood memories using inner child guided imagery; in the third and fourth phases insights gained led to an authentic re-engagement with family members in relationships that had been problematic. The panic attacks resolved and there were two dreams representing a reconfiguring of his relationship with his deceased father. The first two phases were the focus of an unpublished case study presented at a conference in 1995. This article incorporates material from that study and looks back at the case both in light of developments in phases two and three and also in light of theoretical developments in our understanding of complex trauma since the initial presentation.
- Full Text:
- Date Issued: 2013
The human skin blanching assay for in vivo topical corticosteroid assessment. II. Subject- and observer-dependent variation in blanching responses
- Haigh, John M, Meyer, Eric, Smith, Eric W, Kanfer, Isadore
- Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
- Date: 1997
- Language: English
- Type: text , Article
- Identifier: vital:6382 , http://hdl.handle.net/10962/d1006300
- Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
- Full Text:
- Date Issued: 1997
- Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
- Date: 1997
- Language: English
- Type: text , Article
- Identifier: vital:6382 , http://hdl.handle.net/10962/d1006300
- Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
- Full Text:
- Date Issued: 1997
Ectomycorrhizas in association with Pinus patula in Sabie, South Africa
- Hawley, Greer L, Taylor, A F S, Dames, Joanna F
- Authors: Hawley, Greer L , Taylor, A F S , Dames, Joanna F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6475 , http://hdl.handle.net/10962/d1006163 , http://www.scielo.org.za/scielo.php?pid=S0038-23532008000400011&script=sci_arttext
- Description: Forestry is an economically important industry in South Africa,involving extensive exotic plantations of Eucalyptus, Pinus and Acacia species. These tree species have fungal associations, such as ectomycorrhizas, that have become locally naturalized. The forestry industry is increasingly faced with problems of long-term sustainability, increasing soil acidity and depletion of soil nutrients. It is, therefore, essential that the fundamental importance of the ectomycorrhizal (ECM) symbioses in the nutrient cycling, growth, health and survival of these tree species should not be ignored. Research on the species diversity of ECM fungi associated with forestry plant species has been hampered by the difficulty of identifying the fungi involved in the symbiosis. This investigation focused on the ECM fungi associated with Pinus patula (Schlecht. et Cham.) grown in managed plantations in the Sabie region, Mpumalanga province, South Africa. ECM roots were morphotyped and DNA was extracted. The internal transcribed spacer (ITS) region was amplified using the ITS 1F and ITS 4 primers. The sequences were BLASTed using the GenBank and UNITE databases. Twenty-seven extractions were successfully amplified representing 17 different morphotypes. Of the 27 sequences, 21 were identified as ECM fungi and, from the BLAST results, eleven different ECM species could be identified. Selected ECM root types were morphologically and anatomically described according to root morphology, mantle structure, specialized hyphae and rhizomorph arrangement. Seven dominant field types were described and identified as two Amanita species, Scleroderma citrinum, a suilloid species, Thelephora terrestris, a tometelloid species and one resembled an Albatrellus species.
- Full Text:
- Date Issued: 2008
- Authors: Hawley, Greer L , Taylor, A F S , Dames, Joanna F
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6475 , http://hdl.handle.net/10962/d1006163 , http://www.scielo.org.za/scielo.php?pid=S0038-23532008000400011&script=sci_arttext
- Description: Forestry is an economically important industry in South Africa,involving extensive exotic plantations of Eucalyptus, Pinus and Acacia species. These tree species have fungal associations, such as ectomycorrhizas, that have become locally naturalized. The forestry industry is increasingly faced with problems of long-term sustainability, increasing soil acidity and depletion of soil nutrients. It is, therefore, essential that the fundamental importance of the ectomycorrhizal (ECM) symbioses in the nutrient cycling, growth, health and survival of these tree species should not be ignored. Research on the species diversity of ECM fungi associated with forestry plant species has been hampered by the difficulty of identifying the fungi involved in the symbiosis. This investigation focused on the ECM fungi associated with Pinus patula (Schlecht. et Cham.) grown in managed plantations in the Sabie region, Mpumalanga province, South Africa. ECM roots were morphotyped and DNA was extracted. The internal transcribed spacer (ITS) region was amplified using the ITS 1F and ITS 4 primers. The sequences were BLASTed using the GenBank and UNITE databases. Twenty-seven extractions were successfully amplified representing 17 different morphotypes. Of the 27 sequences, 21 were identified as ECM fungi and, from the BLAST results, eleven different ECM species could be identified. Selected ECM root types were morphologically and anatomically described according to root morphology, mantle structure, specialized hyphae and rhizomorph arrangement. Seven dominant field types were described and identified as two Amanita species, Scleroderma citrinum, a suilloid species, Thelephora terrestris, a tometelloid species and one resembled an Albatrellus species.
- Full Text:
- Date Issued: 2008
First evidence for the Cenomanian-Turonian oceanic anoxic event (OAE2, Bonarelli event) from the Ionian Zone, western continental Greece
- Karakitsios, V, Tsikos, Harilaos, Van Breugel, Y, Koletti, L, Sinninghe Damsté, J S, Jenkyns, H C
- Authors: Karakitsios, V , Tsikos, Harilaos , Van Breugel, Y , Koletti, L , Sinninghe Damsté, J S , Jenkyns, H C
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6735 , http://hdl.handle.net/10962/d1007547
- Description: Integrated biostratigraphic (planktonic foraminifera, calcareous nannofossils), chemostratigraphic (bulk C and O isotopes) and compound-specific organic geochemical studies of a mid-Cretaceous pelagic carbonate—black shale succession of the Ionian Zone (western Greece), provide the first evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) in mainland Greece. The event is manifested by the occurrence of a relatively thin (35 cm), yet exceptionally organic carbon-rich (44.5 wt% TOC), carbonate-free black shale, near the Cenomanian–Turonian boundary within the Vigla limestone formation (Berriasian–Turonian). Compared to the ‘Bonarelli’ black-shale interval from the type locality of OAE2 in Marche–Umbria, Italy, this black shale exhibits greatly reduced stratigraphic thickness, coupled with a considerable relative enrichment in TOC. Isotopically, enriched δ[superscript 13]C values for both bulk organic matter (−22.2‰) and specific organic compounds are up to 5‰ higher than those of underlying organic-rich strata of the Aptian-lower Albian Vigla Shale member, and thus compare very well with similar values of Cenomanian–Turonian black shale occurrences elsewhere. The relative predominance of bacterial hopanoids in the saturated, apolar lipid fraction of the OAE2 black shale of the Ionian Zone supports recent findings suggesting the abundance of N[subscript 2]-fixing cyanobacteria in Cretaceous oceans during the Cenomanian–Turonian and early Aptian oceanic anoxic events.
- Full Text:
- Date Issued: 2007
- Authors: Karakitsios, V , Tsikos, Harilaos , Van Breugel, Y , Koletti, L , Sinninghe Damsté, J S , Jenkyns, H C
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6735 , http://hdl.handle.net/10962/d1007547
- Description: Integrated biostratigraphic (planktonic foraminifera, calcareous nannofossils), chemostratigraphic (bulk C and O isotopes) and compound-specific organic geochemical studies of a mid-Cretaceous pelagic carbonate—black shale succession of the Ionian Zone (western Greece), provide the first evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) in mainland Greece. The event is manifested by the occurrence of a relatively thin (35 cm), yet exceptionally organic carbon-rich (44.5 wt% TOC), carbonate-free black shale, near the Cenomanian–Turonian boundary within the Vigla limestone formation (Berriasian–Turonian). Compared to the ‘Bonarelli’ black-shale interval from the type locality of OAE2 in Marche–Umbria, Italy, this black shale exhibits greatly reduced stratigraphic thickness, coupled with a considerable relative enrichment in TOC. Isotopically, enriched δ[superscript 13]C values for both bulk organic matter (−22.2‰) and specific organic compounds are up to 5‰ higher than those of underlying organic-rich strata of the Aptian-lower Albian Vigla Shale member, and thus compare very well with similar values of Cenomanian–Turonian black shale occurrences elsewhere. The relative predominance of bacterial hopanoids in the saturated, apolar lipid fraction of the OAE2 black shale of the Ionian Zone supports recent findings suggesting the abundance of N[subscript 2]-fixing cyanobacteria in Cretaceous oceans during the Cenomanian–Turonian and early Aptian oceanic anoxic events.
- Full Text:
- Date Issued: 2007