ISSRs indicate that Chromolaena odorata invading southern Africa originates in Jamaica or Cuba
- Paterson, Iain D, Zachariades, Coastas
- Authors: Paterson, Iain D , Zachariades, Coastas
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406105 , vital:70239 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.04.005"
- Description: Two biotypes of the invasive alien plant, Chromolaena odorata (L.) R.M. King and Rob. (Asteraceae: Eupatorieae), are recognized in the plant’s introduced distribution. The Asian/West African (A/WA) biotype is present in West and Central Africa, India, Southeast Asia and Oceania, while the southern African (SA) biotype is only present in southern Africa. Biological control using insect natural enemies has been significantly more successful against the A/WA biotype than the SA biotype, suggesting that host plant incompatibility may have resulted in reduced efficacy of biological control agents in southern Africa. Inter-Simple Sequence Repeats (ISSR) were used to identify the origin of the SA biotype as Jamaica or Cuba. The data also confirm that the SA biotype is genetically distinct from the A/WA biotype and that the SA biotype is the result of a separate introduction. Biological control agents for C. odorata in southern Africa should be sourced from Jamaica and Cuba in order to avoid host plant incompatibility problems.
- Full Text:
- Date Issued: 2014
- Authors: Paterson, Iain D , Zachariades, Coastas
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406105 , vital:70239 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.04.005"
- Description: Two biotypes of the invasive alien plant, Chromolaena odorata (L.) R.M. King and Rob. (Asteraceae: Eupatorieae), are recognized in the plant’s introduced distribution. The Asian/West African (A/WA) biotype is present in West and Central Africa, India, Southeast Asia and Oceania, while the southern African (SA) biotype is only present in southern Africa. Biological control using insect natural enemies has been significantly more successful against the A/WA biotype than the SA biotype, suggesting that host plant incompatibility may have resulted in reduced efficacy of biological control agents in southern Africa. Inter-Simple Sequence Repeats (ISSR) were used to identify the origin of the SA biotype as Jamaica or Cuba. The data also confirm that the SA biotype is genetically distinct from the A/WA biotype and that the SA biotype is the result of a separate introduction. Biological control agents for C. odorata in southern Africa should be sourced from Jamaica and Cuba in order to avoid host plant incompatibility problems.
- Full Text:
- Date Issued: 2014
Lever Brothers & Unilever – a practical problem of source?
- Stack, Elizabeth M, Grenville, D P, Poole, Richard, Horn, Edward B, Harnett, Hugh N
- Authors: Stack, Elizabeth M , Grenville, D P , Poole, Richard , Horn, Edward B , Harnett, Hugh N
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/2143 , vital:20259
- Full Text:
- Date Issued: 2014
- Authors: Stack, Elizabeth M , Grenville, D P , Poole, Richard , Horn, Edward B , Harnett, Hugh N
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/2143 , vital:20259
- Full Text:
- Date Issued: 2014
Liberation movements in power: party and state in southern Africa
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144688 , vital:38370 , DOI: 10.1080/21528586.2014.960705
- Description: In Liberation movements in power, Roger Southall provides a rich and refined account of political transformation in three ex-settler colonies in southern Africa, namely, South Africa, Namibia and Zimbabwe. In particular, he focuses on their former hegemonic national liberation movements, namely, the African National Congress (ANC) in South Africa, the South West African People’s Organisation (SWAPO) in Namibia and the Zimbabwe African National Union (ZANU) – now ZANU-Patriotic Front (ZANU-PF) – in Zimbabwe, their metamorphism into political parties and party machines, and their ‘capture’ of state power as the dominant political party subsequent to the end of white settler colonialism and the emergence of non-racial democracy. The general conclusion is that democratic ideals and procedures have become subordinated to the dictates of authoritarian restructuring.
- Full Text:
- Date Issued: 2014
- Authors: Helliker, Kirk D
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144688 , vital:38370 , DOI: 10.1080/21528586.2014.960705
- Description: In Liberation movements in power, Roger Southall provides a rich and refined account of political transformation in three ex-settler colonies in southern Africa, namely, South Africa, Namibia and Zimbabwe. In particular, he focuses on their former hegemonic national liberation movements, namely, the African National Congress (ANC) in South Africa, the South West African People’s Organisation (SWAPO) in Namibia and the Zimbabwe African National Union (ZANU) – now ZANU-Patriotic Front (ZANU-PF) – in Zimbabwe, their metamorphism into political parties and party machines, and their ‘capture’ of state power as the dominant political party subsequent to the end of white settler colonialism and the emergence of non-racial democracy. The general conclusion is that democratic ideals and procedures have become subordinated to the dictates of authoritarian restructuring.
- Full Text:
- Date Issued: 2014
Life satisfaction and education in South Africa: Investigating the role of attainment and the likelihood of education as a positional good
- Authors: Botha, Ferdi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396091 , vital:69149 , xlink:href="https://doi.org/10.1007/s11205-013-0452-2"
- Description: This paper explores various dynamics in the relationship between life satisfaction and education in South Africa using the 2008 National Income Dynamics Survey. The results indicate a strong positive association between educational attainment and individual satisfaction with life, which is true in the overall sample and for men and women. This positive relationship also holds for Black and Coloured individuals, but is insignificant in the Asian and White samples. Evidence indicates that education is a positional good, in that people who have attained more than the mean level of education in their relevant cluster are significantly more satisfied with life compared to those possessing less than the mean education.
- Full Text:
- Date Issued: 2014
- Authors: Botha, Ferdi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396091 , vital:69149 , xlink:href="https://doi.org/10.1007/s11205-013-0452-2"
- Description: This paper explores various dynamics in the relationship between life satisfaction and education in South Africa using the 2008 National Income Dynamics Survey. The results indicate a strong positive association between educational attainment and individual satisfaction with life, which is true in the overall sample and for men and women. This positive relationship also holds for Black and Coloured individuals, but is insignificant in the Asian and White samples. Evidence indicates that education is a positional good, in that people who have attained more than the mean level of education in their relevant cluster are significantly more satisfied with life compared to those possessing less than the mean education.
- Full Text:
- Date Issued: 2014
Lived bodies: women’s experience of sex and gender
- Authors: Lothian, Julie-Anne
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/69445 , vital:29538
- Description: This thesis will discuss the category of women, as a social group, through a phenomenological understanding of women’s subjective experiences. In arguing for the phenomenological perspective of the lived body, I show the ways in which other conceptions of women’s embodied subjectivity ultimately fail to provide comprehensive accounts of the lived experience of being a woman. I begin with an investigation into how biological determinists hypothesise women’s bodies as sexed. I then move to respond to Judith Butler’s poststructuralist feminist account of the gendered body. Finally, I argue that the embodied experience of being a woman is best explained as an ambiguous relationship between socially constructed expectations of femininity and biological materiality.
- Full Text:
- Date Issued: 2014
- Authors: Lothian, Julie-Anne
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/69445 , vital:29538
- Description: This thesis will discuss the category of women, as a social group, through a phenomenological understanding of women’s subjective experiences. In arguing for the phenomenological perspective of the lived body, I show the ways in which other conceptions of women’s embodied subjectivity ultimately fail to provide comprehensive accounts of the lived experience of being a woman. I begin with an investigation into how biological determinists hypothesise women’s bodies as sexed. I then move to respond to Judith Butler’s poststructuralist feminist account of the gendered body. Finally, I argue that the embodied experience of being a woman is best explained as an ambiguous relationship between socially constructed expectations of femininity and biological materiality.
- Full Text:
- Date Issued: 2014
Losing, using, refusing, cruising: first-generation South African women academics narrate the complexity of marginality
- Idahosa, Grace E, Vincent, Louise
- Authors: Idahosa, Grace E , Vincent, Louise
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141820 , vital:38007 , DOI: 10.1080/10130950.2014.874766
- Description: In this article we ask how senior academic women in South Africa narrate their experience of being ‘outside in’ the teaching machine. Wide research literature documents the gross underrepresentation of women in senior positions in the academy. It has been argued that intertwined sexist, patriarchal and phallocentric knowledges and practices in academic institutions produce various forms of discrimination, inequality, oppression and marginalisation. Academic women report feeling invisible and retreating to the margins so as to avoid victimisation and discrimination. Others have pointed to the tension between the ‘tenure clock’ and ‘biological clock’ as a source of anxiety. However, experiences of academic women are not identical. In the context of studies showing the importance of existing personal and social resources, prior experience and having mentors and role models in the negotiation of inequality and discrimination, we document the narratives of women academics who are the first in their families to graduate with a university degree.
- Full Text:
- Date Issued: 2014
- Authors: Idahosa, Grace E , Vincent, Louise
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141820 , vital:38007 , DOI: 10.1080/10130950.2014.874766
- Description: In this article we ask how senior academic women in South Africa narrate their experience of being ‘outside in’ the teaching machine. Wide research literature documents the gross underrepresentation of women in senior positions in the academy. It has been argued that intertwined sexist, patriarchal and phallocentric knowledges and practices in academic institutions produce various forms of discrimination, inequality, oppression and marginalisation. Academic women report feeling invisible and retreating to the margins so as to avoid victimisation and discrimination. Others have pointed to the tension between the ‘tenure clock’ and ‘biological clock’ as a source of anxiety. However, experiences of academic women are not identical. In the context of studies showing the importance of existing personal and social resources, prior experience and having mentors and role models in the negotiation of inequality and discrimination, we document the narratives of women academics who are the first in their families to graduate with a university degree.
- Full Text:
- Date Issued: 2014
Low-cost housing developments in South Africa miss the opportunities for household level urban greening
- Shackleton, Charlie M, Hebinck, Paul, Kaoma, Humphrey, Chishaleshale, Mwale, Chinyimba, Abby, Shackleton, Sheona E, Gambiza, James, Gumbo, Davison
- Authors: Shackleton, Charlie M , Hebinck, Paul , Kaoma, Humphrey , Chishaleshale, Mwale , Chinyimba, Abby , Shackleton, Sheona E , Gambiza, James , Gumbo, Davison
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180967 , vital:43677 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.10.002"
- Description: Most developing countries of the world are experiencing large-scale migration from rural to urban areas. Many new migrants end up in low-cost or informal areas and slums with attendant environmental concerns. One dimension of improved urban sustainability is the provision of green spaces and trees. Whilst many countries have urban greening programmes for public spaces and streets, few have considered the status and potential contribution of trees from resident's own gardens. This paper reports firstly on the policy environment for urban forestry and greening in South Africa and secondly on the maintenance, use and appreciation of trees on private homesteads of residents of new and older low-income suburbs as well as informal housing areas from three small towns in South Africa. In particular we examine if the most recent centrally planned and built low-income housing schemes (called RDP suburbs in South Africa) have considered and incorporated plans or spaces for urban greenery in peoples’ homesteads. We found that broad environmental and sustainability concerns and statements are common in urban development and housing policies, but specific guidelines for implementation are generally absent. More specifically, urban forestry and tree planting are rarely mentioned in the broader land use and environmental policies other than the national forest act and subsequent regulations, but even there it is relatively superficial. In the study towns the prevalence, density and number of species of trees was lowest in the new RDP suburbs relative to the township and informal areas. Consequently, the contribution of tree products to local livelihoods was also lower in the RDP areas. Yet there were no differences in the level of appreciation of the value and intangible benefits of trees between residents from the three different suburbs. This shows that the failure to plan for and accommodate trees in new low-cost housing developments is missing an opportunity to improve overall urban sustainability and liveability and constraining the potential flows of tangible and intangible benefits to urban residents. Making opportunities for such in older suburbs is challenging because of space limitations and cost implications of retrospective provisions, but incorporation into plans for new low-cost housing development should be possible.
- Full Text:
- Date Issued: 2014
- Authors: Shackleton, Charlie M , Hebinck, Paul , Kaoma, Humphrey , Chishaleshale, Mwale , Chinyimba, Abby , Shackleton, Sheona E , Gambiza, James , Gumbo, Davison
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180967 , vital:43677 , xlink:href="https://doi.org/10.1016/j.landusepol.2013.10.002"
- Description: Most developing countries of the world are experiencing large-scale migration from rural to urban areas. Many new migrants end up in low-cost or informal areas and slums with attendant environmental concerns. One dimension of improved urban sustainability is the provision of green spaces and trees. Whilst many countries have urban greening programmes for public spaces and streets, few have considered the status and potential contribution of trees from resident's own gardens. This paper reports firstly on the policy environment for urban forestry and greening in South Africa and secondly on the maintenance, use and appreciation of trees on private homesteads of residents of new and older low-income suburbs as well as informal housing areas from three small towns in South Africa. In particular we examine if the most recent centrally planned and built low-income housing schemes (called RDP suburbs in South Africa) have considered and incorporated plans or spaces for urban greenery in peoples’ homesteads. We found that broad environmental and sustainability concerns and statements are common in urban development and housing policies, but specific guidelines for implementation are generally absent. More specifically, urban forestry and tree planting are rarely mentioned in the broader land use and environmental policies other than the national forest act and subsequent regulations, but even there it is relatively superficial. In the study towns the prevalence, density and number of species of trees was lowest in the new RDP suburbs relative to the township and informal areas. Consequently, the contribution of tree products to local livelihoods was also lower in the RDP areas. Yet there were no differences in the level of appreciation of the value and intangible benefits of trees between residents from the three different suburbs. This shows that the failure to plan for and accommodate trees in new low-cost housing developments is missing an opportunity to improve overall urban sustainability and liveability and constraining the potential flows of tangible and intangible benefits to urban residents. Making opportunities for such in older suburbs is challenging because of space limitations and cost implications of retrospective provisions, but incorporation into plans for new low-cost housing development should be possible.
- Full Text:
- Date Issued: 2014
Mini-review on the use of liquid membranes in the extraction of platinum group metals from mining and metal refinery wastewaters/side-streams
- Moyo, Francis, Tandlich, Roman
- Authors: Moyo, Francis , Tandlich, Roman
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75960 , vital:30487 , DOI: 10.4172/2155-6199.1000228
- Description: The current mini-review focuses on the use of liquid membranes in the platinum group metal (PGM/PGMs) extraction from various types of wastewaters to prevent environmental pollution; and for the metal recovery to address the scarcity of the PGMs in the industrial cycles. The bulk liquid membranes have been used to the extracted PGMs from the (acidic) aqueous media with recoveries of up to 96.3 ± 2.5% of the original PGM amount. The extraction time generally ranges from 2 to 24 hours. The bulk membrane liquid in the PGM extraction will depend on the covalent structure of the extractant, the feed phase PGM concentration and the complex of the PGM in question that is actually extracted from the aqueous environment. The advantages of this type of liquid membrane include its operational simplicity, but the disadvantages include limited possibility to improve the extraction performance of the system. Literature data are encouraging as they indicate that extraction of PGMs from mining and metal-refinery side-streams does not suffer from interference from metal contaminants that are commonly found in the mining and metal refinery side-streams, e.g. iron. Thus further research should focus on the application of ELM to extraction of PGMs from said wastewaters and major research drive should focus on the use of the Taylorvortex column and the non-Newtonian ELMs. With the supported liquid membranes, 78-82% of the original PGM content could be recovered from model side-streams. The selectivity of the extraction for individual PGMs can be controlled by the extractant used.
- Full Text:
- Date Issued: 2014
- Authors: Moyo, Francis , Tandlich, Roman
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75960 , vital:30487 , DOI: 10.4172/2155-6199.1000228
- Description: The current mini-review focuses on the use of liquid membranes in the platinum group metal (PGM/PGMs) extraction from various types of wastewaters to prevent environmental pollution; and for the metal recovery to address the scarcity of the PGMs in the industrial cycles. The bulk liquid membranes have been used to the extracted PGMs from the (acidic) aqueous media with recoveries of up to 96.3 ± 2.5% of the original PGM amount. The extraction time generally ranges from 2 to 24 hours. The bulk membrane liquid in the PGM extraction will depend on the covalent structure of the extractant, the feed phase PGM concentration and the complex of the PGM in question that is actually extracted from the aqueous environment. The advantages of this type of liquid membrane include its operational simplicity, but the disadvantages include limited possibility to improve the extraction performance of the system. Literature data are encouraging as they indicate that extraction of PGMs from mining and metal-refinery side-streams does not suffer from interference from metal contaminants that are commonly found in the mining and metal refinery side-streams, e.g. iron. Thus further research should focus on the application of ELM to extraction of PGMs from said wastewaters and major research drive should focus on the use of the Taylorvortex column and the non-Newtonian ELMs. With the supported liquid membranes, 78-82% of the original PGM content could be recovered from model side-streams. The selectivity of the extraction for individual PGMs can be controlled by the extractant used.
- Full Text:
- Date Issued: 2014
Modelling annual evapotranspiration in a semi-arid, African savanna: functional convergence theory, MODIS LAI and the Penman–Monteith equation
- Palmer, Anthony R, Weideman, Craig I, Finca, Andiswa, Everson, Colin S, Hanan, Niall P, Ellery, William F N
- Authors: Palmer, Anthony R , Weideman, Craig I , Finca, Andiswa , Everson, Colin S , Hanan, Niall P , Ellery, William F N
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144387 , vital:38341 , DOI: 10.2989/10220119.2014.931305
- Description: Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment-scale water balance. We derived ET0 from an automatic weather station 30 km west of Skukuza, Kruger National Park, South Africa using the Penman– Monteith equation, and then used the MODIS LAI to inform the model of canopy phenological dynamics. This result was compared with 173 days of ET measurements from the eddy covariance (ETec) system near Skukuza in 2007 as well as from the ET recorded by a large-aperture scintillometer at the same site in 2005. The model compared favourably with both sets of measured data and, when used independently of the eddy covariance data, ETMODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.
- Full Text:
- Date Issued: 2014
- Authors: Palmer, Anthony R , Weideman, Craig I , Finca, Andiswa , Everson, Colin S , Hanan, Niall P , Ellery, William F N
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144387 , vital:38341 , DOI: 10.2989/10220119.2014.931305
- Description: Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment-scale water balance. We derived ET0 from an automatic weather station 30 km west of Skukuza, Kruger National Park, South Africa using the Penman– Monteith equation, and then used the MODIS LAI to inform the model of canopy phenological dynamics. This result was compared with 173 days of ET measurements from the eddy covariance (ETec) system near Skukuza in 2007 as well as from the ET recorded by a large-aperture scintillometer at the same site in 2005. The model compared favourably with both sets of measured data and, when used independently of the eddy covariance data, ETMODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.
- Full Text:
- Date Issued: 2014
Modelling the spatial and genetic response of the endemic sparid: Polysteganus praeorbitalis (Pisces: Sparidae) to climate change in the Agulhas Current system
- Authors: Isemonger, Devin Neil
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54509 , vital:26576
- Description: The Scotsman Seabream, Polysteganus praeorbitalis, is one of several large, slow-growing members of the Sparidae family of fishes endemic to the Agulhas Current system in the Western Indian Ocean (WIO). Relatively little research has been conducted on this species despite its importance to both recreational and commercial line fisheries in South Africa and the drastic decline in catch per unit effort (CPUE) that has been recorded since the 1940s. Changing sea temperatures as a result of global climate change are further expected to affect the distribution and abundance of many fish species based on their thermal tolerances, life histories and population structures. The ability of these species to shift their distribution and adapt to new environments and thermal conditions will depend to some degree on the levels of genetic variation and gene flow, within and between populations. A combined approach using species distribution modelling and genetic analyses may prove to be a useful tool in investigating the potential effects of climate change on the distribution and genetic diversity of species. An ensemble species distribution model (SDM) based on 205 occurrence records and 30 years of Reynolds Optimum Interpolated (OI) sea surface temperature data was constructed to predict the distributional response of P. praeorbitalis to climate change in the Agulhas Current system. The ensemble SDM displayed a true skill statistic (TSS) of 0.975 and an area under the receiver operating curve (ROC) of 0.999, indicating good model fit. Autumn and winter minimum temperatures, as well as bathymetry, were the most important predictor variables in the majority of models, indicating that these variables may directly constrain the distribution of P. praeorbitalis. In particular, the southern range edge of this species appeared to be constrained by autumn and winter minima, with high model agreement on this range edge. Conversely, the northern range limit showed poor model agreement leading to a gradual reduction in occurrence. This indicates that this range edge may be constrained by other factors not included in the models such as species interactions. The ensemble SDM projected the current range of P. praeorbitalis to be 1500 km², smaller than the published range for this species. The model underestimated the northern range edge of this species by approximately 5° latitude when binary transformed. This is probably due to the rarity of this species in the landings of the Mozambican linefishery, which was assumed to be an indication of low abundance of P. praeorbitalis in these waters. The absence of a specimen to verify the published northern range edge of this species indicates that the northern range edge produced by this model is likely to be closer to the actual range limit of the species. A range contraction of 30% occurring at both the northern and southern edge of P. praeorbitalis’ range and range fragmentation occurring, towards its northern range edge by 2030, was predicted. These changes are modelled to be the results of cooling related to the intensification of the Port Alfred upwelling cell and of warming predicted north of the Natal Bight and in southern Mozambique. Genetic analyses of the nuclear DNA (nDNA) S7 intron 1 and mitochondrial DNA (mtDNA) control region genes were carried out using 118 tissue samples of P. praeorbitalis collected at four main localities: the Eastern Cape, Transkei, southern KwaZulu-Natal and northern KwaZulu-Natal. Analyses of genetic diversity levels revealed relatively low diversity in the mtDNA dataset (Hd = 0.488; π = 0.004) and moderate levels of diversity in the nDNA dataset (Ad = 0.922; π = 0.005). The low levels of diversity observed in the mtDNA dataset might be explained by a number of factors, including high variation in spawning success, the negative effects of over-harvesting, or a recent population bottleneck. The last explanation is supported by characteristic star-shaped haplotype networks and unimodal mismatch distributions displayed by both datasets. These results, in conjunction with a significant (p = 0.005) negative Tajimas D value (-2.029) in the mtDNA dataset and significant (p = 0.0005) negative Fu’s F statistic in both the nDNA (F = -26.5) and mtDNA (F = -11.9) datasets, provide strong evidence for a recent population expansion after a bottleneck event in this species. Spatially, mtDNA diversity was highest in the Eastern Cape and lowest in the middle localities, while nDNA diversity showed the opposite pattern. These results may be indicative of differences in the sex ratio between localities, possibly as a result of the protogynous hermaphroditism that has been postulated for this species. Although pairwise comparisons and exact tests of population differentiation revealed no significant geneticdifferentiation between populations in the mtDNA dataset, there was some evidence of low levels of differentiation in the nDNA dataset. This occurred for comparisons between the Eastern Cape and Transkei (Fst = 0.039; p <0.05), and the northern KwaZulu-Natal (Fst = 0.045; p < 0.05).. This might be the result of one or a combination of factors including the effects of the Port Alfred upwelling cell on dispersal and gene flow, or the possibility of more than one spawning ground for this species promoting sub-structuring. A SAMOVA analyses run on the nDNA dataset maximised variance by grouping the Eastern Cape and southern KwaZulu-Natal together and Transkei and northern KwaZulu-Natal together in two groups. This revealed no evidence of spatial structure (p = 0.36), with only 3.30% of variation explained by this grouping. The removal of individuals below the estimated length at 50% maturity in the nDNA dataset, in order to test for temporal structure, resulted in stronger evidence of differentiation between the Eastern Cape and all other localities: Transkei (Fst = 0.081; p< 0.05), southern KwaZulu-Natal (Fst = 0.031; p<0.05), and northern KwaZulu-Natal (Fst = 0.078; p< 0.05). This indicates that some temporal genetic structure may exist between age classes within this species. The differentiation observed between the Eastern Cape and other localities, coupled with the high percentage of private haplotypes in the mtDNA dataset in this locality, indicates that this area is where P. praeorbitalis is most vulnerable to the potential negative effects of climate change on its genetic diversity. However, the vast majority of this species genetic diversity appears to reside towards the centre of its range where it is most abundant and the lack of strong genetic structure indicates high levels of gene flow. In conclusion, while P. praeorbitalis is vulnerable to range loss as a result of climate change, its genetic diversity is unlikely to be greatly affected.
- Full Text:
- Date Issued: 2014
- Authors: Isemonger, Devin Neil
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54509 , vital:26576
- Description: The Scotsman Seabream, Polysteganus praeorbitalis, is one of several large, slow-growing members of the Sparidae family of fishes endemic to the Agulhas Current system in the Western Indian Ocean (WIO). Relatively little research has been conducted on this species despite its importance to both recreational and commercial line fisheries in South Africa and the drastic decline in catch per unit effort (CPUE) that has been recorded since the 1940s. Changing sea temperatures as a result of global climate change are further expected to affect the distribution and abundance of many fish species based on their thermal tolerances, life histories and population structures. The ability of these species to shift their distribution and adapt to new environments and thermal conditions will depend to some degree on the levels of genetic variation and gene flow, within and between populations. A combined approach using species distribution modelling and genetic analyses may prove to be a useful tool in investigating the potential effects of climate change on the distribution and genetic diversity of species. An ensemble species distribution model (SDM) based on 205 occurrence records and 30 years of Reynolds Optimum Interpolated (OI) sea surface temperature data was constructed to predict the distributional response of P. praeorbitalis to climate change in the Agulhas Current system. The ensemble SDM displayed a true skill statistic (TSS) of 0.975 and an area under the receiver operating curve (ROC) of 0.999, indicating good model fit. Autumn and winter minimum temperatures, as well as bathymetry, were the most important predictor variables in the majority of models, indicating that these variables may directly constrain the distribution of P. praeorbitalis. In particular, the southern range edge of this species appeared to be constrained by autumn and winter minima, with high model agreement on this range edge. Conversely, the northern range limit showed poor model agreement leading to a gradual reduction in occurrence. This indicates that this range edge may be constrained by other factors not included in the models such as species interactions. The ensemble SDM projected the current range of P. praeorbitalis to be 1500 km², smaller than the published range for this species. The model underestimated the northern range edge of this species by approximately 5° latitude when binary transformed. This is probably due to the rarity of this species in the landings of the Mozambican linefishery, which was assumed to be an indication of low abundance of P. praeorbitalis in these waters. The absence of a specimen to verify the published northern range edge of this species indicates that the northern range edge produced by this model is likely to be closer to the actual range limit of the species. A range contraction of 30% occurring at both the northern and southern edge of P. praeorbitalis’ range and range fragmentation occurring, towards its northern range edge by 2030, was predicted. These changes are modelled to be the results of cooling related to the intensification of the Port Alfred upwelling cell and of warming predicted north of the Natal Bight and in southern Mozambique. Genetic analyses of the nuclear DNA (nDNA) S7 intron 1 and mitochondrial DNA (mtDNA) control region genes were carried out using 118 tissue samples of P. praeorbitalis collected at four main localities: the Eastern Cape, Transkei, southern KwaZulu-Natal and northern KwaZulu-Natal. Analyses of genetic diversity levels revealed relatively low diversity in the mtDNA dataset (Hd = 0.488; π = 0.004) and moderate levels of diversity in the nDNA dataset (Ad = 0.922; π = 0.005). The low levels of diversity observed in the mtDNA dataset might be explained by a number of factors, including high variation in spawning success, the negative effects of over-harvesting, or a recent population bottleneck. The last explanation is supported by characteristic star-shaped haplotype networks and unimodal mismatch distributions displayed by both datasets. These results, in conjunction with a significant (p = 0.005) negative Tajimas D value (-2.029) in the mtDNA dataset and significant (p = 0.0005) negative Fu’s F statistic in both the nDNA (F = -26.5) and mtDNA (F = -11.9) datasets, provide strong evidence for a recent population expansion after a bottleneck event in this species. Spatially, mtDNA diversity was highest in the Eastern Cape and lowest in the middle localities, while nDNA diversity showed the opposite pattern. These results may be indicative of differences in the sex ratio between localities, possibly as a result of the protogynous hermaphroditism that has been postulated for this species. Although pairwise comparisons and exact tests of population differentiation revealed no significant geneticdifferentiation between populations in the mtDNA dataset, there was some evidence of low levels of differentiation in the nDNA dataset. This occurred for comparisons between the Eastern Cape and Transkei (Fst = 0.039; p <0.05), and the northern KwaZulu-Natal (Fst = 0.045; p < 0.05).. This might be the result of one or a combination of factors including the effects of the Port Alfred upwelling cell on dispersal and gene flow, or the possibility of more than one spawning ground for this species promoting sub-structuring. A SAMOVA analyses run on the nDNA dataset maximised variance by grouping the Eastern Cape and southern KwaZulu-Natal together and Transkei and northern KwaZulu-Natal together in two groups. This revealed no evidence of spatial structure (p = 0.36), with only 3.30% of variation explained by this grouping. The removal of individuals below the estimated length at 50% maturity in the nDNA dataset, in order to test for temporal structure, resulted in stronger evidence of differentiation between the Eastern Cape and all other localities: Transkei (Fst = 0.081; p< 0.05), southern KwaZulu-Natal (Fst = 0.031; p<0.05), and northern KwaZulu-Natal (Fst = 0.078; p< 0.05). This indicates that some temporal genetic structure may exist between age classes within this species. The differentiation observed between the Eastern Cape and other localities, coupled with the high percentage of private haplotypes in the mtDNA dataset in this locality, indicates that this area is where P. praeorbitalis is most vulnerable to the potential negative effects of climate change on its genetic diversity. However, the vast majority of this species genetic diversity appears to reside towards the centre of its range where it is most abundant and the lack of strong genetic structure indicates high levels of gene flow. In conclusion, while P. praeorbitalis is vulnerable to range loss as a result of climate change, its genetic diversity is unlikely to be greatly affected.
- Full Text:
- Date Issued: 2014
National substantive agreement on wages and conditions of employment concluded between Pioneer Foods (Pty) Ltd t/a Essential Foods: Bakeries and Food and Allied Workers Union.
- Pioneer Foods (Pty) Ltd, Essential Foods: Bakeries, Food and Allied Workers Union
- Authors: Pioneer Foods (Pty) Ltd , Essential Foods: Bakeries , Food and Allied Workers Union
- Date: 2014
- Subjects: Pioneer Foods (Pty) Ltd , Essential Foods: Bakeries , Food and Allied Workers Union , Collective bargaining -- South Africa , Wages -- South Africa
- Language: English
- Type: collective labor agreements , text
- Identifier: http://hdl.handle.net/10962/96130 , vital:31240 , Labour Research Service (LRS)
- Description: National substantive agreement on wages and conditions of employment concluded between Pioneer Foods (Pty) Ltd t/a Essential Foods: Bakeries and Food and Allied Workers Union.
- Full Text:
- Date Issued: 2014
- Authors: Pioneer Foods (Pty) Ltd , Essential Foods: Bakeries , Food and Allied Workers Union
- Date: 2014
- Subjects: Pioneer Foods (Pty) Ltd , Essential Foods: Bakeries , Food and Allied Workers Union , Collective bargaining -- South Africa , Wages -- South Africa
- Language: English
- Type: collective labor agreements , text
- Identifier: http://hdl.handle.net/10962/96130 , vital:31240 , Labour Research Service (LRS)
- Description: National substantive agreement on wages and conditions of employment concluded between Pioneer Foods (Pty) Ltd t/a Essential Foods: Bakeries and Food and Allied Workers Union.
- Full Text:
- Date Issued: 2014
Natural resource products contribute to poverty mitigation amongst urbanising communities in sub-saharan Africa
- Shackleton, Charlie M, Schlesinger, Johannes, Kaoma, Humphrey, Davenport, N I, Ward, Catherine D, Evans, Michelle L, Drescher, Axel W
- Authors: Shackleton, Charlie M , Schlesinger, Johannes , Kaoma, Humphrey , Davenport, N I , Ward, Catherine D , Evans, Michelle L , Drescher, Axel W
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:6624 , http://hdl.handle.net/10962/d1016232
- Description: [From Introduction] Urbanisation in sub-Saharan Africa: changing the locus of poverty. Urbanisation is a global phenomenon that is changing the face of the Earth, as well as how people earn a living and secure their livelihoods. In 2006 the number of urban people in the world surpassed the number of rural people, and this gap will continue to grow. In only 16 years (by 2030) just under two-thirds of the world's people will be urban dwellers. Whilst most of the developed world and large parts of Latin America already have more than threequarters of their populations living in cities and towns, most countries in Asia and sub-Saharan Africa are still catching up. This means that they are experiencing massive migrations from rural to urban areas as rural people wish to swap the insecurities of rural living for the allure of secure employment and better services for health, education, sanitation and transport in towns and cities. Sub-Saharan Africa (SSA) is the most rapidly urbanising region of the globe. According to UN-Habitat, in 1990, only 28 % of the region's inhabitants lived in towns and cities; that increased to approximately 32 % in 2001 and 41 % in 2010. The size of the urban population is likely to surpass the rural one around 2025. Contrary to popular belief, most urban residents in SSA (and globally) live in small towns rather than massive megacities; with just over half living in towns of less than 200,000 people and 78 % living in towns of less than 500,000 residents. Only 14 % of urban dwellers live in cities of more than one million people. Many new urban households maintain strong links to relatives and clans in rural areas, with circular migration patterns emerging as the urban transition takes place over several decades. The implications of this extremely rapid urbanisation in SSA countries for livelihoods and poverty are widely debated. UN-Habitat highlights a relatively unique aspect of urbanisation in SSA as being the accompanying high rate of growth in informal settlements or slums. In other words, not all rural migrants to towns and cities find secure incomes or shelter. Some slum areas have become permanent features where inter-generational poverty is reproduced. Although urban areas are producing an increasing share of national wealth in SSA countries, some argue that slowly the nexus of poverty is shifting towards urban areas. Rates of poverty are high in rural areas of SSA, but migration and internal population growth means that in some countries the number of urban poor almost matches the number of rural poor, and it is likely to grow. The informal economy contributes an average of 40 – 45 % of total urban GDP, which is higher than any other region of the world.
- Full Text:
- Date Issued: 2014
- Authors: Shackleton, Charlie M , Schlesinger, Johannes , Kaoma, Humphrey , Davenport, N I , Ward, Catherine D , Evans, Michelle L , Drescher, Axel W
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:6624 , http://hdl.handle.net/10962/d1016232
- Description: [From Introduction] Urbanisation in sub-Saharan Africa: changing the locus of poverty. Urbanisation is a global phenomenon that is changing the face of the Earth, as well as how people earn a living and secure their livelihoods. In 2006 the number of urban people in the world surpassed the number of rural people, and this gap will continue to grow. In only 16 years (by 2030) just under two-thirds of the world's people will be urban dwellers. Whilst most of the developed world and large parts of Latin America already have more than threequarters of their populations living in cities and towns, most countries in Asia and sub-Saharan Africa are still catching up. This means that they are experiencing massive migrations from rural to urban areas as rural people wish to swap the insecurities of rural living for the allure of secure employment and better services for health, education, sanitation and transport in towns and cities. Sub-Saharan Africa (SSA) is the most rapidly urbanising region of the globe. According to UN-Habitat, in 1990, only 28 % of the region's inhabitants lived in towns and cities; that increased to approximately 32 % in 2001 and 41 % in 2010. The size of the urban population is likely to surpass the rural one around 2025. Contrary to popular belief, most urban residents in SSA (and globally) live in small towns rather than massive megacities; with just over half living in towns of less than 200,000 people and 78 % living in towns of less than 500,000 residents. Only 14 % of urban dwellers live in cities of more than one million people. Many new urban households maintain strong links to relatives and clans in rural areas, with circular migration patterns emerging as the urban transition takes place over several decades. The implications of this extremely rapid urbanisation in SSA countries for livelihoods and poverty are widely debated. UN-Habitat highlights a relatively unique aspect of urbanisation in SSA as being the accompanying high rate of growth in informal settlements or slums. In other words, not all rural migrants to towns and cities find secure incomes or shelter. Some slum areas have become permanent features where inter-generational poverty is reproduced. Although urban areas are producing an increasing share of national wealth in SSA countries, some argue that slowly the nexus of poverty is shifting towards urban areas. Rates of poverty are high in rural areas of SSA, but migration and internal population growth means that in some countries the number of urban poor almost matches the number of rural poor, and it is likely to grow. The informal economy contributes an average of 40 – 45 % of total urban GDP, which is higher than any other region of the world.
- Full Text:
- Date Issued: 2014
Necrophiliac Narration and the Business of Friends: Damon Galgut’s The Good Doctor
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144159 , vital:38316 , DOI: 10.1080/17533171.2014.918406
- Description: Set in the period following South Africa’s first democratic elections, Damon Galgut’s The Good Doctor traces the friendship that develops between two doctors working at a rural hospital. While it does not deal overtly with the politics of the “new” South Africa, the novel’s treatment of friendship, which cuts across the distinction between the private and the public, reflects obliquely on the nature of the emerging democratic dispensation. In this paper, I explore the link that Galgut constructs between friendship and community, and argue that his portrayal of the former points to the possibility of a form of community that is premised on a “common strangeness.”
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144159 , vital:38316 , DOI: 10.1080/17533171.2014.918406
- Description: Set in the period following South Africa’s first democratic elections, Damon Galgut’s The Good Doctor traces the friendship that develops between two doctors working at a rural hospital. While it does not deal overtly with the politics of the “new” South Africa, the novel’s treatment of friendship, which cuts across the distinction between the private and the public, reflects obliquely on the nature of the emerging democratic dispensation. In this paper, I explore the link that Galgut constructs between friendship and community, and argue that his portrayal of the former points to the possibility of a form of community that is premised on a “common strangeness.”
- Full Text:
- Date Issued: 2014
Occurrence of larval fishes in a rocky shore-associated nursery area in temperate South Africa, with emphasis on temperature-related growth in dominant Sparidae
- Strydom, Nadine A, Booth, Anthony J, McLachlan, A
- Authors: Strydom, Nadine A , Booth, Anthony J , McLachlan, A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125342 , vital:35774 , https://doi.10.2989/1814232X.2014.899269
- Description: Larval fishes were studied in Shark Bay on the warm, temperate south-east coast of South Africa. The bay is a small, shallow, subtidal area associated with a rocky shore. Sampling took place fortnightly for a period of one year (September 2004–August 2005) to assess composition, abundance and growth of fishes. The objectives of the study were to assess the extent of use of this habitat type by larvae throughout the year and to ascertain what temperature advantages this relatively warm habitat could have on growth of dominant species. A total of 10 fish families, represented by 16 taxa, was collected using a specially modified beach seine net (mesh aperture 500 μm). Shark Bay was utilised extensively by Diplodus capensis and Sarpa salpa and to a lesser extent by Clinus supercilious, Liza spp. and Mugil cephalus. Mean catch per unit effort (CPUE) of larvae was high (>500 larvae per net haul), peaking at ~7 500 larvae in a single haul that consisted mostly of postflexion-stage Sparidae. There was a weak, negative correlation (−0.24) between temperature and overall CPUE, which reflected either the seasonality or protracted nature of spawning by the species occurring in the bay. There was no significant difference in CPUE between the moon phases sampled on the spring tides in this study. Shark Bay was dominated by postflexionstage larvae, consisting in particular of species common to tide pools during the juvenile stage. Certain species were sampled for only short periods during the year. The year-round occurrence and high abundance of the two dominant species indicate that Shark Bay represents an important nursery habitat for the completion of the larval phase. These species exhibited exponential growth that lagged behind small increases in temperature, highlighting the importance of access to shallow, warm habitat that allows larval growth to increase, leading to earlier settlement into juvenile habitat and thereby reducing the pelagic larval duration.
- Full Text:
- Date Issued: 2014
- Authors: Strydom, Nadine A , Booth, Anthony J , McLachlan, A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125342 , vital:35774 , https://doi.10.2989/1814232X.2014.899269
- Description: Larval fishes were studied in Shark Bay on the warm, temperate south-east coast of South Africa. The bay is a small, shallow, subtidal area associated with a rocky shore. Sampling took place fortnightly for a period of one year (September 2004–August 2005) to assess composition, abundance and growth of fishes. The objectives of the study were to assess the extent of use of this habitat type by larvae throughout the year and to ascertain what temperature advantages this relatively warm habitat could have on growth of dominant species. A total of 10 fish families, represented by 16 taxa, was collected using a specially modified beach seine net (mesh aperture 500 μm). Shark Bay was utilised extensively by Diplodus capensis and Sarpa salpa and to a lesser extent by Clinus supercilious, Liza spp. and Mugil cephalus. Mean catch per unit effort (CPUE) of larvae was high (>500 larvae per net haul), peaking at ~7 500 larvae in a single haul that consisted mostly of postflexion-stage Sparidae. There was a weak, negative correlation (−0.24) between temperature and overall CPUE, which reflected either the seasonality or protracted nature of spawning by the species occurring in the bay. There was no significant difference in CPUE between the moon phases sampled on the spring tides in this study. Shark Bay was dominated by postflexionstage larvae, consisting in particular of species common to tide pools during the juvenile stage. Certain species were sampled for only short periods during the year. The year-round occurrence and high abundance of the two dominant species indicate that Shark Bay represents an important nursery habitat for the completion of the larval phase. These species exhibited exponential growth that lagged behind small increases in temperature, highlighting the importance of access to shallow, warm habitat that allows larval growth to increase, leading to earlier settlement into juvenile habitat and thereby reducing the pelagic larval duration.
- Full Text:
- Date Issued: 2014
Ocean warming affects the distribution and abundance of resident fishes by changing their reproductive scope
- Potts, Warren M, Booth, Anthony J, Richardson, Timothy J, Sauer, Warwick H H
- Authors: Potts, Warren M , Booth, Anthony J , Richardson, Timothy J , Sauer, Warwick H H
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125352 , vital:35775 , https://doi.10.1007/s11160-013-9329-3
- Description: With ocean warming predicted globally, one of the mechanisms driving distributional shifts and changes in the abundance of resident fishes is reproductive output. The relationship between sea surface temperature and the reproductive activity of a eurythermic, resident coastal species, blacktail seabream Diplodus sargus capensis, was examined in the ‘‘ocean warming’’ hotspot of the northern Benguela. Reproductive activity was found to be restricted to periods when the water temperature dropped below 20 _C. A metadata analysis conducted on the D. sargus sub-species complex similarly showed that reproductive activity was restricted to temperatures between 15 and 20 _C, regardless of the range in ambient water temperature. Based on these findings and using satellite derived SST information, we examined D. s. capensis’s total and seasonal ‘‘reproductive scope’’ that is defined as either the area suitable for spawning each year or the duration of its potential spawning season at a fixed geographical locality, respectively. Trends were examined over the last three decades. Reproductive scope by area was found to be shrinking at a rate of 7 % per decade in southern Angola and expanding at a rate of 6 % per decade in northern Namibia. Reproductive scope by season decreased by 1.05 months per decade in Namibe, southern Angola and increased by 0.76 months per decade in Hentiesbaai, northern Namibia. Changes in reproductive scope may be a driving mechanism of distributional shifts in resident fishes, although the rate of the shifts is likely to be slow. More importantly, changes in reproductive scope will not be uniform throughout fish distributions and will most likely result in heterogeneous variations in fish abundance.
- Full Text:
- Date Issued: 2014
- Authors: Potts, Warren M , Booth, Anthony J , Richardson, Timothy J , Sauer, Warwick H H
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125352 , vital:35775 , https://doi.10.1007/s11160-013-9329-3
- Description: With ocean warming predicted globally, one of the mechanisms driving distributional shifts and changes in the abundance of resident fishes is reproductive output. The relationship between sea surface temperature and the reproductive activity of a eurythermic, resident coastal species, blacktail seabream Diplodus sargus capensis, was examined in the ‘‘ocean warming’’ hotspot of the northern Benguela. Reproductive activity was found to be restricted to periods when the water temperature dropped below 20 _C. A metadata analysis conducted on the D. sargus sub-species complex similarly showed that reproductive activity was restricted to temperatures between 15 and 20 _C, regardless of the range in ambient water temperature. Based on these findings and using satellite derived SST information, we examined D. s. capensis’s total and seasonal ‘‘reproductive scope’’ that is defined as either the area suitable for spawning each year or the duration of its potential spawning season at a fixed geographical locality, respectively. Trends were examined over the last three decades. Reproductive scope by area was found to be shrinking at a rate of 7 % per decade in southern Angola and expanding at a rate of 6 % per decade in northern Namibia. Reproductive scope by season decreased by 1.05 months per decade in Namibe, southern Angola and increased by 0.76 months per decade in Hentiesbaai, northern Namibia. Changes in reproductive scope may be a driving mechanism of distributional shifts in resident fishes, although the rate of the shifts is likely to be slow. More importantly, changes in reproductive scope will not be uniform throughout fish distributions and will most likely result in heterogeneous variations in fish abundance.
- Full Text:
- Date Issued: 2014
Ocean warming hotspots provide early warning laboratories for climate change impacts
- Pecl, Gretta T, Hobday, Alistair J, Frusher, Stewart, Sauer, Warwick H H, Bates, Amanda E
- Authors: Pecl, Gretta T , Hobday, Alistair J , Frusher, Stewart , Sauer, Warwick H H , Bates, Amanda E
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125363 , vital:35776 , https://doi.10.1007/s11160-014-9355-9
- Description: A growing literature describes a wide range of negative impacts of climate change on marine resources and the people and communities they support, including species range changes, changes in productivity of fisheries and declines in economic performance (Doney et al. 2012; Poloczanska et al. 2013). These impacts, many of which are projected to increase in future, are compounded by growing pressures on marine resources (Halpern et al. 2008; Maxwell et al. 2013). An estimated 260 million people are involved directly or indirectly in global marine fisheries (Teh and Sumaila 2013) with many of the resources for capture fisheries already fully (&57 % in 2009) or over exploited (30 %) (FAO 2012). Nevertheless, production of marine resources will need to increase to accommodate the demands of a growing population, and the impacts of climate change on food security will need to be minimised (FAO 2009). Identifying opportunities and threats, and developing adaptation options in response to climate change impacts in the marine realm, is essential for optimising the benefits that society can continue to derive from the goods and services provided by marine resources.
- Full Text:
- Date Issued: 2014
- Authors: Pecl, Gretta T , Hobday, Alistair J , Frusher, Stewart , Sauer, Warwick H H , Bates, Amanda E
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125363 , vital:35776 , https://doi.10.1007/s11160-014-9355-9
- Description: A growing literature describes a wide range of negative impacts of climate change on marine resources and the people and communities they support, including species range changes, changes in productivity of fisheries and declines in economic performance (Doney et al. 2012; Poloczanska et al. 2013). These impacts, many of which are projected to increase in future, are compounded by growing pressures on marine resources (Halpern et al. 2008; Maxwell et al. 2013). An estimated 260 million people are involved directly or indirectly in global marine fisheries (Teh and Sumaila 2013) with many of the resources for capture fisheries already fully (&57 % in 2009) or over exploited (30 %) (FAO 2012). Nevertheless, production of marine resources will need to increase to accommodate the demands of a growing population, and the impacts of climate change on food security will need to be minimised (FAO 2009). Identifying opportunities and threats, and developing adaptation options in response to climate change impacts in the marine realm, is essential for optimising the benefits that society can continue to derive from the goods and services provided by marine resources.
- Full Text:
- Date Issued: 2014
Ocean warming, a rapid distributional shift, and the hybridization of a coastal fish species
- Potts, Warren M, Henriques, Romina, Santos, Carmen V D, Munnik, Kate, Ansorge, Isabelle J, Dufois, Francois, Sauer, Warwick H H, Booth, Anthony J, Kirchner, Carola, Sauer, Warwick, Shaw, Paul W
- Authors: Potts, Warren M , Henriques, Romina , Santos, Carmen V D , Munnik, Kate , Ansorge, Isabelle J , Dufois, Francois , Sauer, Warwick H H , Booth, Anthony J , Kirchner, Carola , Sauer, Warwick , Shaw, Paul W
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125375 , vital:35777 , https://doi.10.1111/gcb.12612
- Description: Despite increasing awareness of large-scale climate-driven distribution shifts in the marine environment, no study has linked rapid ocean warming to a shift in distribution and consequent hybridization of a marine fish species. This study describes rapid warming (0.8 °C per decade) in the coastal waters of the Angola-Benguela Frontal Zone over the last three decades and a concomitant shift by a temperature sensitive coastal fish species (Argyrosomus coronus) southward from Angola into Namibia. In this context, rapid shifts in distribution across Economic Exclusive Zones will complicate the management of fishes, particularly when there is a lack of congruence in the fisheries policy between nations. Evidence for recent hybridization between A. coronus and a congener, A. inodorus, indicate that the rapid shift in distribution of A. coronus has placed adults of the two species in contact during their spawning events. Ocean warming may therefore revert established species isolation mechanisms and alter the evolutionary history of fishes. While the consequences of the hybridization on the production of the resource remain unclear, this will most likely introduce additional layers of complexity to their management.
- Full Text:
- Date Issued: 2014
- Authors: Potts, Warren M , Henriques, Romina , Santos, Carmen V D , Munnik, Kate , Ansorge, Isabelle J , Dufois, Francois , Sauer, Warwick H H , Booth, Anthony J , Kirchner, Carola , Sauer, Warwick , Shaw, Paul W
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125375 , vital:35777 , https://doi.10.1111/gcb.12612
- Description: Despite increasing awareness of large-scale climate-driven distribution shifts in the marine environment, no study has linked rapid ocean warming to a shift in distribution and consequent hybridization of a marine fish species. This study describes rapid warming (0.8 °C per decade) in the coastal waters of the Angola-Benguela Frontal Zone over the last three decades and a concomitant shift by a temperature sensitive coastal fish species (Argyrosomus coronus) southward from Angola into Namibia. In this context, rapid shifts in distribution across Economic Exclusive Zones will complicate the management of fishes, particularly when there is a lack of congruence in the fisheries policy between nations. Evidence for recent hybridization between A. coronus and a congener, A. inodorus, indicate that the rapid shift in distribution of A. coronus has placed adults of the two species in contact during their spawning events. Ocean warming may therefore revert established species isolation mechanisms and alter the evolutionary history of fishes. While the consequences of the hybridization on the production of the resource remain unclear, this will most likely introduce additional layers of complexity to their management.
- Full Text:
- Date Issued: 2014
Ontogenetic and seasonal shifts in the diet of Diplodus cervinus hottentotus (Pisces: Sparidae) in southern Angola
- Winkler, Alexander C, Santos, Carmen V D, Potts, Warren M
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125452 , vital:35784 , https://doi.10.2989/1814232X.2014.951392
- Description: Fishes of the family Sparidae occupy a diverse range of trophic niches, from herbivores to generalist omnivores and specialist predators (Hanel and Tsigenopoulos 2011). Feeding specialisation in this family is facilitated by diversity in tooth type and anterior jaw arrangement (Vandewalle et al. 1995). Other fish families, such as Cyprinidae and Labridae, have developed crushing pharyngeal teeth to process their food. Sparids, however, have retained a simple pharyngeal tooth arrangement and instead have developed molariform teeth to process hard-shelled molluscs and invertebrate prey. Hanel and Tsigenopoulos (2011) suggested that this alternate strategy is a major factor facilitating the trophic diversity in sparid fishes.
- Full Text:
- Date Issued: 2014
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125452 , vital:35784 , https://doi.10.2989/1814232X.2014.951392
- Description: Fishes of the family Sparidae occupy a diverse range of trophic niches, from herbivores to generalist omnivores and specialist predators (Hanel and Tsigenopoulos 2011). Feeding specialisation in this family is facilitated by diversity in tooth type and anterior jaw arrangement (Vandewalle et al. 1995). Other fish families, such as Cyprinidae and Labridae, have developed crushing pharyngeal teeth to process their food. Sparids, however, have retained a simple pharyngeal tooth arrangement and instead have developed molariform teeth to process hard-shelled molluscs and invertebrate prey. Hanel and Tsigenopoulos (2011) suggested that this alternate strategy is a major factor facilitating the trophic diversity in sparid fishes.
- Full Text:
- Date Issued: 2014
Optical nonlinearities and photophysicochemical behaviour of green and blue forms of lutetium bisphthalocyanines
- Sekhosana, Kutloana Edith, Amuhaya, Edith, Mack, John, Nyokong, Tebello
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
Optical nonlinearities in non-peripherally substituted pyridyloxy phthalocyanines
- Sanusi, Kayode, Antunes, Edith M, Nyokong, Tebello
- Authors: Sanusi, Kayode , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241618 , vital:50955 , xlink:href="https://doi.org/10.1039/C3DT52462K"
- Description: The optical nonlinearities of six non-peripherally-substituted pyridyloxy phthalocyanines have been studied at 532 nm using a nanosecond Z-scan technique in a dimethyl sulphoxide solution. Ring-strain effects and the absence of a metal center were found to greatly reduce the inherent high nonlinearities expected of some of these phthalocyanine complexes. Of the six molecules investigated, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyaninato lead(II) 3, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyanine 5, and 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyanine 6 were found to exhibit negligible nonlinear optical behavior, due to either the absence of asymmetry or central metal and/or the presence of a ring-strain effect. A two-photon absorption process was found to be the major contributor to the observed reverse saturable absorption (RSA) in 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyaninato lead(II) 4, 1(4)-mono-(2-pyridyloxy)phthalocyaninato lead(II) 7, and 1(4)-mono-(4-pyridyloxy)phthalocyaninato lead(II) 8, with large two-photon absorption cross-section, high hyperpolarizability and high third-order susceptibility values in the range of 4.53 × 10−43–5.33 × 10−42 cm4 s per photon, 1.61 × 10−28–1.89 × 10−27 esu and 9.73 × 10−12–7.05 × 10−11 esu respectively.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241618 , vital:50955 , xlink:href="https://doi.org/10.1039/C3DT52462K"
- Description: The optical nonlinearities of six non-peripherally-substituted pyridyloxy phthalocyanines have been studied at 532 nm using a nanosecond Z-scan technique in a dimethyl sulphoxide solution. Ring-strain effects and the absence of a metal center were found to greatly reduce the inherent high nonlinearities expected of some of these phthalocyanine complexes. Of the six molecules investigated, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyaninato lead(II) 3, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyanine 5, and 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyanine 6 were found to exhibit negligible nonlinear optical behavior, due to either the absence of asymmetry or central metal and/or the presence of a ring-strain effect. A two-photon absorption process was found to be the major contributor to the observed reverse saturable absorption (RSA) in 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyaninato lead(II) 4, 1(4)-mono-(2-pyridyloxy)phthalocyaninato lead(II) 7, and 1(4)-mono-(4-pyridyloxy)phthalocyaninato lead(II) 8, with large two-photon absorption cross-section, high hyperpolarizability and high third-order susceptibility values in the range of 4.53 × 10−43–5.33 × 10−42 cm4 s per photon, 1.61 × 10−28–1.89 × 10−27 esu and 9.73 × 10−12–7.05 × 10−11 esu respectively.
- Full Text:
- Date Issued: 2014