Impact of invasive alien plants on water provision in selected catchments
- Preston, Ian R, Le Maitre, D C, Blignaut, J N, Louw, Lynette, Palmer, Carolyn G
- Authors: Preston, Ian R , Le Maitre, D C , Blignaut, J N , Louw, Lynette , Palmer, Carolyn G
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437979 , vital:73426 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/44_04_20_33741.pdf
- Description: We analyse the impact of failing to control invasive alien plants (IAPs) on the water supply to the Berg River and De Hoop Dams, in other words, the opportunity cost of not clearing IAPs in these two catch-ments. To do this we used models to assess and compare the impact of current and future invasions on inflows into the dams. Although the clearing of current invasions would only provide a modest increase in the amount of water compared to, for example, the construction of an-other dam, failure to clear the invasion will have a negative impact on water security in the long term. We estimated that the Berg River Dam could lose up to 51% of its mean annual inflows to IAPs over a 45-year period, and the De Hoop Dam catchment could lose up to 44%. These impacts would continue to increase over time, and the costs of control could become very high as the plants invade rugged terrain. Major in-frastructural development requires Ministerial approval, supported by advice from senior officials. We suggest that such advice should sub-stantively take sufficient account of the benefits of clearing existing in-vasions, or at least of preventing further invasions. Our results suggest that serious consequences arise from insufficient investment in catch-ment management. An integrated approach to the management of the supply of and demand for water, that ensures long-term sustainability, is essential in informed decision-making and the early control of IAPs is a key component of that approach.
- Full Text:
- Date Issued: 2018
- Authors: Preston, Ian R , Le Maitre, D C , Blignaut, J N , Louw, Lynette , Palmer, Carolyn G
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437979 , vital:73426 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/44_04_20_33741.pdf
- Description: We analyse the impact of failing to control invasive alien plants (IAPs) on the water supply to the Berg River and De Hoop Dams, in other words, the opportunity cost of not clearing IAPs in these two catch-ments. To do this we used models to assess and compare the impact of current and future invasions on inflows into the dams. Although the clearing of current invasions would only provide a modest increase in the amount of water compared to, for example, the construction of an-other dam, failure to clear the invasion will have a negative impact on water security in the long term. We estimated that the Berg River Dam could lose up to 51% of its mean annual inflows to IAPs over a 45-year period, and the De Hoop Dam catchment could lose up to 44%. These impacts would continue to increase over time, and the costs of control could become very high as the plants invade rugged terrain. Major in-frastructural development requires Ministerial approval, supported by advice from senior officials. We suggest that such advice should sub-stantively take sufficient account of the benefits of clearing existing in-vasions, or at least of preventing further invasions. Our results suggest that serious consequences arise from insufficient investment in catch-ment management. An integrated approach to the management of the supply of and demand for water, that ensures long-term sustainability, is essential in informed decision-making and the early control of IAPs is a key component of that approach.
- Full Text:
- Date Issued: 2018
Major security incidents since 2014: an African perspective
- Van Heerden, Renier, Von Solms, Sune, Vorster, Johannes
- Authors: Van Heerden, Renier , Von Solms, Sune , Vorster, Johannes
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68291 , vital:29234 , https://ieeexplore.ieee.org/abstract/document/8417326/
- Description: Publisher version , The integration of technology in the modern society provides many benefits, but with increased connectivity comes increased risk where governments, businesses and individuals are vulnerable to a variety of cyber-attacks. Many of the large information security attacks of the last decade can be seen as an attack on 'foreign” systems or individuals when viewed from an African perspective, with no direct impact on an individual in Africa. However, information security experts in Africa states that although some of these attacks might not have had a direct impact of the African individual, but never the less should not be ignored as it does indirectly influence the African individual. The experts state that even if the individuals or businesses are not directly influenced by an attack, it should not be ignored as similar attacks might influence them in the future. They emphasise that these attacks should improve their cybersecurity awareness and behaviour, in order to prevent similar attacks from impacting them.
- Full Text: false
- Date Issued: 2018
- Authors: Van Heerden, Renier , Von Solms, Sune , Vorster, Johannes
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68291 , vital:29234 , https://ieeexplore.ieee.org/abstract/document/8417326/
- Description: Publisher version , The integration of technology in the modern society provides many benefits, but with increased connectivity comes increased risk where governments, businesses and individuals are vulnerable to a variety of cyber-attacks. Many of the large information security attacks of the last decade can be seen as an attack on 'foreign” systems or individuals when viewed from an African perspective, with no direct impact on an individual in Africa. However, information security experts in Africa states that although some of these attacks might not have had a direct impact of the African individual, but never the less should not be ignored as it does indirectly influence the African individual. The experts state that even if the individuals or businesses are not directly influenced by an attack, it should not be ignored as similar attacks might influence them in the future. They emphasise that these attacks should improve their cybersecurity awareness and behaviour, in order to prevent similar attacks from impacting them.
- Full Text: false
- Date Issued: 2018
Marine resource management and conservation in the Anthropocene
- Aswani, Shankar, Basurto, Xavier, Ferse, Sebastian C A, Glaser, Marion, Campbell, Lisa, Cinner, Joshua E, Dalton, Tracey, Jenkins, Lekelia D, Miller, Marc L, Pollnac, Richard, McGill University, Christie, Patrick
- Authors: Aswani, Shankar , Basurto, Xavier , Ferse, Sebastian C A , Glaser, Marion , Campbell, Lisa , Cinner, Joshua E , Dalton, Tracey , Jenkins, Lekelia D , Miller, Marc L , Pollnac, Richard , McGill University , Christie, Patrick
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124987 , vital:35716 , https://doi.10.1017/S0376892917000431
- Description: Because the Anthropocene by definition is an epoch during which environmental change is largely anthropogenic and driven by social, economic, psychological and political forces, environmental social scientists can effectively analyse human behaviour and knowledge systems in this context. In this subject review, we summarize key ways in which the environmental social sciences can better inform fisheries management policy and practice and marine conservation in the Anthropocene. We argue that environmental social scientists are particularly well positioned to synergize research to fill the gaps between: (1) local behaviours/needs/worldviews and marine resource management and biological conservation concerns; and (2) large-scale drivers of planetary environmental change (globalization, affluence, technological change, etc.) and local cognitive, socioeconomic, cultural and historical processes that shape human behaviour in the marine environment. To illustrate this, we synthesize the roles of various environmental social science disciplines in better understanding the interaction between humans and tropical marine ecosystems in developing nations where issues arising from human–coastal interactions are particularly pronounced. We focus on: (1) the application of the environmental social sciences in marine resource management and conservation; (2) the development of ‘new’ socially equitable marine conservation; (3) repopulating the seascape; (4) incorporating multi-scale dynamics of marine social–ecological systems; and (5) envisioning the future of marine resource management and conservation for producing policies and projects for comprehensive and successful resource management and conservation in the Anthropocene.
- Full Text:
- Date Issued: 2018
- Authors: Aswani, Shankar , Basurto, Xavier , Ferse, Sebastian C A , Glaser, Marion , Campbell, Lisa , Cinner, Joshua E , Dalton, Tracey , Jenkins, Lekelia D , Miller, Marc L , Pollnac, Richard , McGill University , Christie, Patrick
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124987 , vital:35716 , https://doi.10.1017/S0376892917000431
- Description: Because the Anthropocene by definition is an epoch during which environmental change is largely anthropogenic and driven by social, economic, psychological and political forces, environmental social scientists can effectively analyse human behaviour and knowledge systems in this context. In this subject review, we summarize key ways in which the environmental social sciences can better inform fisheries management policy and practice and marine conservation in the Anthropocene. We argue that environmental social scientists are particularly well positioned to synergize research to fill the gaps between: (1) local behaviours/needs/worldviews and marine resource management and biological conservation concerns; and (2) large-scale drivers of planetary environmental change (globalization, affluence, technological change, etc.) and local cognitive, socioeconomic, cultural and historical processes that shape human behaviour in the marine environment. To illustrate this, we synthesize the roles of various environmental social science disciplines in better understanding the interaction between humans and tropical marine ecosystems in developing nations where issues arising from human–coastal interactions are particularly pronounced. We focus on: (1) the application of the environmental social sciences in marine resource management and conservation; (2) the development of ‘new’ socially equitable marine conservation; (3) repopulating the seascape; (4) incorporating multi-scale dynamics of marine social–ecological systems; and (5) envisioning the future of marine resource management and conservation for producing policies and projects for comprehensive and successful resource management and conservation in the Anthropocene.
- Full Text:
- Date Issued: 2018
Rinistachya hilleri gen. et sp. nov.(Sphenophyllales), from the upper Devonian of South Africa
- Prestianni, Cyrille, Gess, Robert W
- Authors: Prestianni, Cyrille , Gess, Robert W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73883 , vital:30238 , https://doi.org/10.1007/s13127-018-0385-3
- Description: A rich and diverse plant assemblage has been excavated from latest Devonian (Famennian) black shales of the Witpoort Formation (Witteberg Group) at Waterloo Farm, close to the city of Grahamstown (South Africa). Several specimens of a new sphenopsid have been collected. The description of this as a new taxon, here named Rinistachya hilleri, gen. et sp. nov., provides an important addition to the scarce early record of the group. Rinistachya hilleri presents a novel architecture that include apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia). Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales. Rinistachya furthermore represents the first record of a Devonian sphenopsid from Gondwana and extends the known distribution of the Sphenopsida from the tropics to very high palaeolatitudes. It is a new sphenopsid with a peculiar organisation. The new taxon allows better characterization of the initial evolutionary radiation at the base of the group.
- Full Text:
- Date Issued: 2018
- Authors: Prestianni, Cyrille , Gess, Robert W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73883 , vital:30238 , https://doi.org/10.1007/s13127-018-0385-3
- Description: A rich and diverse plant assemblage has been excavated from latest Devonian (Famennian) black shales of the Witpoort Formation (Witteberg Group) at Waterloo Farm, close to the city of Grahamstown (South Africa). Several specimens of a new sphenopsid have been collected. The description of this as a new taxon, here named Rinistachya hilleri, gen. et sp. nov., provides an important addition to the scarce early record of the group. Rinistachya hilleri presents a novel architecture that include apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia). Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales. Rinistachya furthermore represents the first record of a Devonian sphenopsid from Gondwana and extends the known distribution of the Sphenopsida from the tropics to very high palaeolatitudes. It is a new sphenopsid with a peculiar organisation. The new taxon allows better characterization of the initial evolutionary radiation at the base of the group.
- Full Text:
- Date Issued: 2018
Synergies between research organisations and the wider community in enhancing weed biological control in South Africa
- Martin, Grant D, Hill, Martin P, Coetzee, Julie A, Weaver, Kim N, Hill, Jaclyn M
- Authors: Martin, Grant D , Hill, Martin P , Coetzee, Julie A , Weaver, Kim N , Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68452 , vital:29258 , https://doi.org/10.1007/s10526-017-9846-4
- Description: Biological control offers a cost effective and ecologically sustainable tool for the management of invasive alien plants. Its implementation, however, has historically been slow and poorly co-ordinated. In South Africa, as in many other countries, most aspects of biological control programmes were done by researchers, but from 1995 onwards, with the advent of the Working for Water Programme, a more inclusive approach to biological control has been adopted. In this paper, we report on the development of community-based biological control implementation programmes in South Africa, after 1995, and highlight a number of initiatives, including employing persons with disabilities at mass-rearing facilities and in particular, we outline a suite of educational and outreach programmes for the general public and for schools, which have increased capacity, education and employment in the field of weed biological control.
- Full Text:
- Date Issued: 2018
- Authors: Martin, Grant D , Hill, Martin P , Coetzee, Julie A , Weaver, Kim N , Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68452 , vital:29258 , https://doi.org/10.1007/s10526-017-9846-4
- Description: Biological control offers a cost effective and ecologically sustainable tool for the management of invasive alien plants. Its implementation, however, has historically been slow and poorly co-ordinated. In South Africa, as in many other countries, most aspects of biological control programmes were done by researchers, but from 1995 onwards, with the advent of the Working for Water Programme, a more inclusive approach to biological control has been adopted. In this paper, we report on the development of community-based biological control implementation programmes in South Africa, after 1995, and highlight a number of initiatives, including employing persons with disabilities at mass-rearing facilities and in particular, we outline a suite of educational and outreach programmes for the general public and for schools, which have increased capacity, education and employment in the field of weed biological control.
- Full Text:
- Date Issued: 2018
The energy transition patterns of low-income households in South Africa: an evaluation of energy programme and policy
- Israel-Akinbo, Sylvia O, Snowball, Jeanette D, Fraser, Gavin C G
- Authors: Israel-Akinbo, Sylvia O , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69397 , vital:29518 , https://doi.org/10.17159/2413-3051/2018/v29i3a3310
- Description: The transition to modern energy carriers like electricity is an important way to achieve to eradicate energy poverty. This study investigated energy transition patterns and trends in low-income South African households. The marginal effects of the different determinants on the probability of choosing a specific energy carrier were computed and the influence of some endogenous characteristics in transitioning to modern energy carriers was explored. It was found that energy ladder behaviour exists for cooking while energy stacking was most likely for space heating and the pattern for lighting tended towards energy stacking. Dwelling type, household size and geographical location were among the key determinants of the energy transition pattern. Policies to reduce energy poverty need a multi-pronged approach and not only a focus on electricity access.
- Full Text:
- Date Issued: 2018
- Authors: Israel-Akinbo, Sylvia O , Snowball, Jeanette D , Fraser, Gavin C G
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69397 , vital:29518 , https://doi.org/10.17159/2413-3051/2018/v29i3a3310
- Description: The transition to modern energy carriers like electricity is an important way to achieve to eradicate energy poverty. This study investigated energy transition patterns and trends in low-income South African households. The marginal effects of the different determinants on the probability of choosing a specific energy carrier were computed and the influence of some endogenous characteristics in transitioning to modern energy carriers was explored. It was found that energy ladder behaviour exists for cooking while energy stacking was most likely for space heating and the pattern for lighting tended towards energy stacking. Dwelling type, household size and geographical location were among the key determinants of the energy transition pattern. Policies to reduce energy poverty need a multi-pronged approach and not only a focus on electricity access.
- Full Text:
- Date Issued: 2018
The generation and characterisation of neutralising antibodies against the Theiler’s murine encephalomyelitis virus (TMEV) GDVII capsid reveals the potential binding site of the host cell co-receptor, heparan sulfate:
- Upfold, Nicole, Ross, Caroline J, Tastan Bishop, Özlem, Luke, Garry A, Knox, Caroline M
- Authors: Upfold, Nicole , Ross, Caroline J , Tastan Bishop, Özlem , Luke, Garry A , Knox, Caroline M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148181 , vital:38717 , DOI: 10.1016/j.virusres.2017.11.017
- Description: The early stages of picornavirus capsid assembly and the host factors involved are poorly understood. Since the localisation of viral proteins in infected cells can provide information on their function, antibodies against purified Theiler's murine encephalomyelitis virus (TMEV) GDVII capsids were generated by immunisation of rabbits. The resultant anti-TMEV capsid antibodies recognised a C-terminal region of VP1 but not VP2 or VP3 by Western analysis. Examination of the sites of TMEV capsid assembly by indirect immunofluorescence and confocal microscopy showed that at 5 h post infection, capsid signal was diffusely cytoplasmic with strong perinuclear staining and moved into large punctate structures from 6 to 8 h post infection.
- Full Text:
- Date Issued: 2018
- Authors: Upfold, Nicole , Ross, Caroline J , Tastan Bishop, Özlem , Luke, Garry A , Knox, Caroline M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148181 , vital:38717 , DOI: 10.1016/j.virusres.2017.11.017
- Description: The early stages of picornavirus capsid assembly and the host factors involved are poorly understood. Since the localisation of viral proteins in infected cells can provide information on their function, antibodies against purified Theiler's murine encephalomyelitis virus (TMEV) GDVII capsids were generated by immunisation of rabbits. The resultant anti-TMEV capsid antibodies recognised a C-terminal region of VP1 but not VP2 or VP3 by Western analysis. Examination of the sites of TMEV capsid assembly by indirect immunofluorescence and confocal microscopy showed that at 5 h post infection, capsid signal was diffusely cytoplasmic with strong perinuclear staining and moved into large punctate structures from 6 to 8 h post infection.
- Full Text:
- Date Issued: 2018
The relation between galaxy density and radio jet power for 1.4 GHz VLA selected AGNs in Stripe 82
- Kolwa, S, Jarvis, M J, McAlpine, Kim, Heywood, Ian
- Authors: Kolwa, S , Jarvis, M J , McAlpine, Kim , Heywood, Ian
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/131444 , vital:36572 , https://doi.org/10.1093/mnras/sty3019
- Description: Using a Karl G. Jansky Very Large Array (VLA) L-band (1-2 GHz) survey covering ∼100 deg2 of the Stripe 82 field, we have obtained a catalogue of 2716 radio AGNs. For these AGNs, we investigate the impact of galaxy density on 1.4 GHz radio luminosity (L1.4). We determine their close environment densities using the surface density parameter, ΣN, for N = 2 and N = 5, which we bin by redshift to obtain a pseudo-3D galaxy density measure. Matching the radio AGNs to sources without radio detections in terms of redshift, K-band magnitude and (g − K) colour index, we obtain samples of control galaxies and determine whether radio AGN environments differ from this general population.
- Full Text:
- Date Issued: 2018
- Authors: Kolwa, S , Jarvis, M J , McAlpine, Kim , Heywood, Ian
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/131444 , vital:36572 , https://doi.org/10.1093/mnras/sty3019
- Description: Using a Karl G. Jansky Very Large Array (VLA) L-band (1-2 GHz) survey covering ∼100 deg2 of the Stripe 82 field, we have obtained a catalogue of 2716 radio AGNs. For these AGNs, we investigate the impact of galaxy density on 1.4 GHz radio luminosity (L1.4). We determine their close environment densities using the surface density parameter, ΣN, for N = 2 and N = 5, which we bin by redshift to obtain a pseudo-3D galaxy density measure. Matching the radio AGNs to sources without radio detections in terms of redshift, K-band magnitude and (g − K) colour index, we obtain samples of control galaxies and determine whether radio AGN environments differ from this general population.
- Full Text:
- Date Issued: 2018
The sound of reading
- Authors: Berold, Robert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458754 , vital:75769 , https://hdl.handle.net/10520/EJC-1061c76543
- Description: This essay recounts, in autobiographical form, how poetry transformed me. It began at school with an unanticipated response to the internal music of a poem. Later, drawn primarily by sound and image, I responded to form, texture, ideas and movement in particular poems. These poems and poets – a few of them quoted here – woke me into an awareness of where I was, and gave me the courage to live with my confusion.
- Full Text:
- Date Issued: 2018
- Authors: Berold, Robert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458754 , vital:75769 , https://hdl.handle.net/10520/EJC-1061c76543
- Description: This essay recounts, in autobiographical form, how poetry transformed me. It began at school with an unanticipated response to the internal music of a poem. Later, drawn primarily by sound and image, I responded to form, texture, ideas and movement in particular poems. These poems and poets – a few of them quoted here – woke me into an awareness of where I was, and gave me the courage to live with my confusion.
- Full Text:
- Date Issued: 2018
Trophic preference of southern African dung beetles (Scarabaeoidea: Scarabaeinae and Aphodiinae) and its influence on bioindicator surveys:
- Tocco, Claudia, Balmer, Jonathan P, Villet, Martin H
- Authors: Tocco, Claudia , Balmer, Jonathan P , Villet, Martin H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140796 , vital:37919 , DOI: 10.1111/aje.12523
- Description: Environmental assessments using bioindicators gain value if the interpretability of the indicator used is high, and it is clear how survey methods affect survey comparisons. Because dung beetles are favoured as bioindicators, we studied the trophic preference of a southern African beetle community and its potential effects on surveys of beetle diversity using manual sampling of droppings and pitfall traps baited with carnivore, ruminant or nonruminant dung. Manual sampling showed no significant differences between dung types in either dung beetles abundance or species richness. Generalised linear mixed models of total and endocoprid abundances, species richness and Real Shannon index of trap samples showed higher dung beetle diversity associated with ruminant than with nonruminant dung, which in turn was significantly preferred over carnivore dung.
- Full Text:
- Date Issued: 2018
- Authors: Tocco, Claudia , Balmer, Jonathan P , Villet, Martin H
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140796 , vital:37919 , DOI: 10.1111/aje.12523
- Description: Environmental assessments using bioindicators gain value if the interpretability of the indicator used is high, and it is clear how survey methods affect survey comparisons. Because dung beetles are favoured as bioindicators, we studied the trophic preference of a southern African beetle community and its potential effects on surveys of beetle diversity using manual sampling of droppings and pitfall traps baited with carnivore, ruminant or nonruminant dung. Manual sampling showed no significant differences between dung types in either dung beetles abundance or species richness. Generalised linear mixed models of total and endocoprid abundances, species richness and Real Shannon index of trap samples showed higher dung beetle diversity associated with ruminant than with nonruminant dung, which in turn was significantly preferred over carnivore dung.
- Full Text:
- Date Issued: 2018
A comparative study of the dosimetric features of α-Al2O3: C, Mg and α-Al2O3: C
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/113058 , vital:33694 , https://doi.org/10.1093/rpd/ncx039
- Description: A comparative study of the dosimetric features of α-Al2O3:C,Mg and α-Al2O3:C relevant to thermoluminescence dosimetry is reported. A glow curve of α-Al2O3:C,Mg measured at 1°C/s after beta irradiation to 1 Gy shows two subsidiary peaks at 42°C (labelled as I) and 72°C (II) and the main peak at 161°C (III) whereas a glow curve of α-Al2O3:C measured under the same conditions shows the main peak at 178°C (II′) and a lower intensity peak at 48°C (I′). Apart from these ones, there are several other peaks at temperatures beyond that of the main peak in both α-Al2O3:C,Mg and α-Al2O3:C. However, the latter are not included in this study. We report a comparative quantitative analysis of dose response and fading of peaks I, II and III of α-Al2O3:C,Mg and peaks I′ and II′ of α-Al2O3:C. Analysis shows that the dose response of peaks I and III is sublinear within 1–10 Gy whereas that of peak II is superlinear within 1–4 Gy followed by a sublinear region within 4–10 Gy. In comparison, the dose response of peak I′ is superlinear within 1–4 Gy followed by a sublinear region within 4–10 Gy whereas that of peak II′ is sublinear within 1–4 Gy followed by a superlinear region within 4–10 Gy. As regards to fading corresponding to 1 Gy, peak I is very unstable and fades within 300 s, peak II is more stable and takes up to 43200 s to fade. In comparison, peak III fades down to 30% of its initial intensity within 2400 s. Interestingly, between 2400 and 800 s, the intensity fades by 17% only. Regarding fading in α-Al2O3:C, peak I′ fades within 600 s whereas peak II′ shows an inverse fading behaviour up to 64800 s. The rate of fading for peaks I, II and III in α-Al2O3:C,Mg was found to decrease with increase in dose. However, no such behaviour was observed in α-Al2O3:C. The fading in both samples is discussed on the basis of a charge hopping mechanism.
- Full Text:
- Date Issued: 2017
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/113058 , vital:33694 , https://doi.org/10.1093/rpd/ncx039
- Description: A comparative study of the dosimetric features of α-Al2O3:C,Mg and α-Al2O3:C relevant to thermoluminescence dosimetry is reported. A glow curve of α-Al2O3:C,Mg measured at 1°C/s after beta irradiation to 1 Gy shows two subsidiary peaks at 42°C (labelled as I) and 72°C (II) and the main peak at 161°C (III) whereas a glow curve of α-Al2O3:C measured under the same conditions shows the main peak at 178°C (II′) and a lower intensity peak at 48°C (I′). Apart from these ones, there are several other peaks at temperatures beyond that of the main peak in both α-Al2O3:C,Mg and α-Al2O3:C. However, the latter are not included in this study. We report a comparative quantitative analysis of dose response and fading of peaks I, II and III of α-Al2O3:C,Mg and peaks I′ and II′ of α-Al2O3:C. Analysis shows that the dose response of peaks I and III is sublinear within 1–10 Gy whereas that of peak II is superlinear within 1–4 Gy followed by a sublinear region within 4–10 Gy. In comparison, the dose response of peak I′ is superlinear within 1–4 Gy followed by a sublinear region within 4–10 Gy whereas that of peak II′ is sublinear within 1–4 Gy followed by a superlinear region within 4–10 Gy. As regards to fading corresponding to 1 Gy, peak I is very unstable and fades within 300 s, peak II is more stable and takes up to 43200 s to fade. In comparison, peak III fades down to 30% of its initial intensity within 2400 s. Interestingly, between 2400 and 800 s, the intensity fades by 17% only. Regarding fading in α-Al2O3:C, peak I′ fades within 600 s whereas peak II′ shows an inverse fading behaviour up to 64800 s. The rate of fading for peaks I, II and III in α-Al2O3:C,Mg was found to decrease with increase in dose. However, no such behaviour was observed in α-Al2O3:C. The fading in both samples is discussed on the basis of a charge hopping mechanism.
- Full Text:
- Date Issued: 2017
Abortion in legal, social, and healthcare contexts
- Marecek, Jeanne, Macleod, Catriona I, Hoggart, Lesley
- Authors: Marecek, Jeanne , Macleod, Catriona I , Hoggart, Lesley
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68478 , vital:29262 , https://doi.org/10.1177/0959353516689521
- Description: Publisher version , From Introduction: The subject of abortion is both timely and of high relevance to feminists. In the past few months, women’s access to abortion has been contested in various parts of the world. In many countries in Latin America, the Zika outbreak raised the demand for abortions among pregnant women who had contracted (or feared contracting) the virus, with its risk of severe foetal abnormalities. In Poland, mass demonstrations by women succeeded in turning back proposed legislation prohibiting abortions. The outcome of the U.S. elections in late 2016 raised grave concerns about the future of American women’s access to abortion, which was already limited by stringent regulations and funding restrictions. We chose the title ‘‘Abortion in Context’’ to signal that we sought to publish work that moved beyond examining abortion as a ‘‘stress experience’’ encountered by individual women or as a possible precursor of mental illness. Our goal was to assemble a set of articles that would prompt readers to think critically about practices and discourses surrounding abortion. We further hoped to include work that would address the meanings and practices of abortion in the global South and among minoritized groups in the global North. We were pleased by the enthusiastic response to our Call for Papers. We note that Eklund and Purewal (2017, this issue) address abortion in China and India. Thoradeniya’s (2017, this issue) review of Abortion in Asia (Whittaker, 2010) provides a glimpse of the complex and varied practices, policies, and experiences of abortion in parts of South and Southeast Asia. Chiweshe, Mavuso, and Macleod (whose work will appear in Part 2 of the Special Issue) take up abortion in South Africa and Zimbabwe. Le Grice and Braun (whose work will also appear in Part 2), examine Maori perspectives on abortion. In this Part 1 of the Special Issue, we present work that locates abortion practices and policies in legal, social, and healthcare contexts. Women’s efforts to exercise agency with regard to bodily integrity in the context of pregnancy are shaped most obviously by the legal regulations in the jurisdictions where they live, but they are also shaped by social and cultural issues, biotechnological advances, and healthcare systems. The articles offer detailed examinations of some of these complex contextual framings of abortion.
- Full Text:
- Date Issued: 2017
- Authors: Marecek, Jeanne , Macleod, Catriona I , Hoggart, Lesley
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68478 , vital:29262 , https://doi.org/10.1177/0959353516689521
- Description: Publisher version , From Introduction: The subject of abortion is both timely and of high relevance to feminists. In the past few months, women’s access to abortion has been contested in various parts of the world. In many countries in Latin America, the Zika outbreak raised the demand for abortions among pregnant women who had contracted (or feared contracting) the virus, with its risk of severe foetal abnormalities. In Poland, mass demonstrations by women succeeded in turning back proposed legislation prohibiting abortions. The outcome of the U.S. elections in late 2016 raised grave concerns about the future of American women’s access to abortion, which was already limited by stringent regulations and funding restrictions. We chose the title ‘‘Abortion in Context’’ to signal that we sought to publish work that moved beyond examining abortion as a ‘‘stress experience’’ encountered by individual women or as a possible precursor of mental illness. Our goal was to assemble a set of articles that would prompt readers to think critically about practices and discourses surrounding abortion. We further hoped to include work that would address the meanings and practices of abortion in the global South and among minoritized groups in the global North. We were pleased by the enthusiastic response to our Call for Papers. We note that Eklund and Purewal (2017, this issue) address abortion in China and India. Thoradeniya’s (2017, this issue) review of Abortion in Asia (Whittaker, 2010) provides a glimpse of the complex and varied practices, policies, and experiences of abortion in parts of South and Southeast Asia. Chiweshe, Mavuso, and Macleod (whose work will appear in Part 2 of the Special Issue) take up abortion in South Africa and Zimbabwe. Le Grice and Braun (whose work will also appear in Part 2), examine Maori perspectives on abortion. In this Part 1 of the Special Issue, we present work that locates abortion practices and policies in legal, social, and healthcare contexts. Women’s efforts to exercise agency with regard to bodily integrity in the context of pregnancy are shaped most obviously by the legal regulations in the jurisdictions where they live, but they are also shaped by social and cultural issues, biotechnological advances, and healthcare systems. The articles offer detailed examinations of some of these complex contextual framings of abortion.
- Full Text:
- Date Issued: 2017
Alex Baine's women's emancipation in Uganda: a visual archive of the history of a new generation of women in Uganda
- Authors: Tumusiime, Amanda
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145631 , vital:38453 , https://0-doi.org.wam.seals.ac.za/10.1162/AFAR_a_00344
- Description: Alex Baine is a contemporary Ugandan woman artist who graduated from the Margaret Trowell School of Industrial and Fine Art (or MTSIFA) in 1989. During her final year, she painted a large work, Women's Emancipation in Uganda (Fig. 1) (1989), in which she represented women in domestic and nondomestic (conventional and unconventional) economies, spaces, and histories. Baine has not produced any other painting since her graduation. It is evident that Baine's art career, like those of several other female graduates of the Art School, has been interrupted by many issues including family, business, further education, and diversion into other professions. However, in this article I acknowledge that she championed women's emancipation in Uganda's contemporary art in the 1980s, a debate that I trace in her work.
- Full Text:
- Date Issued: 2017
- Authors: Tumusiime, Amanda
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145631 , vital:38453 , https://0-doi.org.wam.seals.ac.za/10.1162/AFAR_a_00344
- Description: Alex Baine is a contemporary Ugandan woman artist who graduated from the Margaret Trowell School of Industrial and Fine Art (or MTSIFA) in 1989. During her final year, she painted a large work, Women's Emancipation in Uganda (Fig. 1) (1989), in which she represented women in domestic and nondomestic (conventional and unconventional) economies, spaces, and histories. Baine has not produced any other painting since her graduation. It is evident that Baine's art career, like those of several other female graduates of the Art School, has been interrupted by many issues including family, business, further education, and diversion into other professions. However, in this article I acknowledge that she championed women's emancipation in Uganda's contemporary art in the 1980s, a debate that I trace in her work.
- Full Text:
- Date Issued: 2017
Birds feeding on aloe nectar: do camera traps and point counts produce comparable data?
- Craig, Christie A, Hunter, Cayley, Craig, Adrian J F K, Hulley, Patrick E
- Authors: Craig, Christie A , Hunter, Cayley , Craig, Adrian J F K , Hulley, Patrick E
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465336 , vital:76595 , https://journals.uct.ac.za/index.php/BO/article/view/467/485
- Description: This paper represents a single season of camera trapping at aloes. We found that point counts recorded more species and therefore gave a broader picture of species diversity in the area. The differences between the two methods indicate caution in relying on just one method for this type of survey. Since camera traps focus on the aloes, they capture primarily birds feeding on nectar. The two methods should be regarded as complementary, since both an overview of the avifauna and the activity of individual species is important in analysing differences between seasons.
- Full Text:
- Date Issued: 2017
- Authors: Craig, Christie A , Hunter, Cayley , Craig, Adrian J F K , Hulley, Patrick E
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465336 , vital:76595 , https://journals.uct.ac.za/index.php/BO/article/view/467/485
- Description: This paper represents a single season of camera trapping at aloes. We found that point counts recorded more species and therefore gave a broader picture of species diversity in the area. The differences between the two methods indicate caution in relying on just one method for this type of survey. Since camera traps focus on the aloes, they capture primarily birds feeding on nectar. The two methods should be regarded as complementary, since both an overview of the avifauna and the activity of individual species is important in analysing differences between seasons.
- Full Text:
- Date Issued: 2017
Community entomology: insects, science and society
- Weaver, Kim N, Hill, Jaclyn M, Martin, Grant D, Paterson, Iain D, Coetzee, Julie A, Hill, Martin P
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
- Full Text:
- Date Issued: 2017
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
- Full Text:
- Date Issued: 2017
Comprehensive kinetic analysis of thermoluminescence peaks of α-Al2O3: C, Mg
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116142 , vital:34323 , https://doi.org/10.1016/j.jlumin.2017.01.003
- Description: A comprehensive kinetic analysis of the glow peaks in α-Al2O3:C,Mg is reported. A thermoluminescence glow curve measured at 1 °C/s after beta irradiation to 1 Gy shows a high intensity peak hereafter referred to as the main peak at 161 °C and six lower intensity secondary peaks at 42, 72, 193, 279, 330, 370 °C respectively. For ease of reference, the secondary peaks are labelled as I, II, IV, V, VI and VII respectively and the main peak denoted peak III. Kinetic analysis of the glow peaks has been carried out using the initial rise, whole glow peak, peak shape, variable heating rate and glow curve deconvolution methods as well as by way of phosphorescence. Using Tm-Tstop, Tm-dose and phosphorescence analyses, the order of kinetics of the peaks has been evaluated as first order. Analysis by the peak shape, whole glow peak and deconvolution methods produce the same conclusion. The activation energy of peaks I through VII are calculated as ~0.83, 0.96, 1.37, 1.20, 1.15, 1.61 and 1.94 eV respectively. The frequency factors for all the peaks are of the order of 109 to 1014 s−1. The question of thermal quenching affecting the peaks was considered. The peaks III, IV and V, the only ones that could be conveniently studied in this regard, were found to be affected by thermal quenching. The activation energy for thermal quenching was calculated for peak III as 0.96±0.03 eV, for peak VI as 0.95±0.07 eV and for peak V as 1.26±0.08 eV. The thermal quenching phenomenon has been discussed with reference to F+ and F centres. An energy band model has been developed to discuss the luminescence mechanisms in α-Al2O3:C,Mg in light of finding in this work.
- Full Text: false
- Date Issued: 2017
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116142 , vital:34323 , https://doi.org/10.1016/j.jlumin.2017.01.003
- Description: A comprehensive kinetic analysis of the glow peaks in α-Al2O3:C,Mg is reported. A thermoluminescence glow curve measured at 1 °C/s after beta irradiation to 1 Gy shows a high intensity peak hereafter referred to as the main peak at 161 °C and six lower intensity secondary peaks at 42, 72, 193, 279, 330, 370 °C respectively. For ease of reference, the secondary peaks are labelled as I, II, IV, V, VI and VII respectively and the main peak denoted peak III. Kinetic analysis of the glow peaks has been carried out using the initial rise, whole glow peak, peak shape, variable heating rate and glow curve deconvolution methods as well as by way of phosphorescence. Using Tm-Tstop, Tm-dose and phosphorescence analyses, the order of kinetics of the peaks has been evaluated as first order. Analysis by the peak shape, whole glow peak and deconvolution methods produce the same conclusion. The activation energy of peaks I through VII are calculated as ~0.83, 0.96, 1.37, 1.20, 1.15, 1.61 and 1.94 eV respectively. The frequency factors for all the peaks are of the order of 109 to 1014 s−1. The question of thermal quenching affecting the peaks was considered. The peaks III, IV and V, the only ones that could be conveniently studied in this regard, were found to be affected by thermal quenching. The activation energy for thermal quenching was calculated for peak III as 0.96±0.03 eV, for peak VI as 0.95±0.07 eV and for peak V as 1.26±0.08 eV. The thermal quenching phenomenon has been discussed with reference to F+ and F centres. An energy band model has been developed to discuss the luminescence mechanisms in α-Al2O3:C,Mg in light of finding in this work.
- Full Text: false
- Date Issued: 2017
Determination of species and instars of the larvae of the Afrotropical species of Thanatophilus Leach, 1817 (Coleoptera, Silphidae)
- Daniel, Claire A, Midgley, John M, Villet, Martin H
- Authors: Daniel, Claire A , Midgley, John M , Villet, Martin H
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440652 , vital:73800 , https://doi.org/10.3897/ AfrInvertebr.58.12966
- Description: Thanatophilus micans and T. mutilatus have significance for forensic entomology. Their larvae are therefore described and a key is provided for identifying the larvae of Afrotropical Silphidae based on morphological characters. It is shown that seven common species of Thanatophilus can be distinguished by a 360 bp mtDNA sequence from the cytochrome oxidase I gene.
- Full Text:
- Date Issued: 2017
- Authors: Daniel, Claire A , Midgley, John M , Villet, Martin H
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440652 , vital:73800 , https://doi.org/10.3897/ AfrInvertebr.58.12966
- Description: Thanatophilus micans and T. mutilatus have significance for forensic entomology. Their larvae are therefore described and a key is provided for identifying the larvae of Afrotropical Silphidae based on morphological characters. It is shown that seven common species of Thanatophilus can be distinguished by a 360 bp mtDNA sequence from the cytochrome oxidase I gene.
- Full Text:
- Date Issued: 2017
Education and the common good
- Authors: Lotz-Sisitka, Heila
- Date: 2017
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/126060 , vital:35846 , ISBN 9783319513225 , https://link.springer.com/chapter/10.1007/978-3-319-51322-5_5?utm_source=twitter&utm_medium=social&utm_content=ads&utm_campaign=SRHS_2_VB_Edu-Series-FTA-Nine#citeas , https://doi.org/10.1007/978-3-319-51322-5_5
- Description: The chapter responds to a recent invitation by the UNESCO to respond to the contents of their book on the purpose of education, entitled Rethinking Education: Towards a Global Common Good? I explore the concept of the common good (as it relates to concepts of commons and commoning activity) and what it might mean to engage with commoning as an educational activity, if the commons, as argued by Amin and Howell, is to be “released” from historical descriptions of commons and commoning activity, to embrace a futures orientation. Drawing on critical realism and decolonization theory, as well as experience of working with expansive social learning, I propose that an educational theory grounded in a concept of emergence is needed in such a context.
- Full Text: false
- Date Issued: 2017
- Authors: Lotz-Sisitka, Heila
- Date: 2017
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/126060 , vital:35846 , ISBN 9783319513225 , https://link.springer.com/chapter/10.1007/978-3-319-51322-5_5?utm_source=twitter&utm_medium=social&utm_content=ads&utm_campaign=SRHS_2_VB_Edu-Series-FTA-Nine#citeas , https://doi.org/10.1007/978-3-319-51322-5_5
- Description: The chapter responds to a recent invitation by the UNESCO to respond to the contents of their book on the purpose of education, entitled Rethinking Education: Towards a Global Common Good? I explore the concept of the common good (as it relates to concepts of commons and commoning activity) and what it might mean to engage with commoning as an educational activity, if the commons, as argued by Amin and Howell, is to be “released” from historical descriptions of commons and commoning activity, to embrace a futures orientation. Drawing on critical realism and decolonization theory, as well as experience of working with expansive social learning, I propose that an educational theory grounded in a concept of emergence is needed in such a context.
- Full Text: false
- Date Issued: 2017
Education for sustainable development in the Namibian Biology curriculum
- Authors: Tshiningayamwe, Sirrka
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436223 , vital:73250 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_8
- Description: As a response to the United Nations Decade of Education for Sustainable Development, Namibia has incorporated Educa-tion for Sustainable Development (ESD) into its education poli-cy. There has thus been a growing recognition of the signifi-cance of ESD across the school curriculum. However, of the various subjects taught in secondary schools, science sub-jects (especially biology) are often perceived as subjects that can make a significant contribution to ESD. Drawing on re-search that was conducted at three schools in Windhoek, this chapter will comment critically on the uptake of ESD in the Bi-ology Namibian Senior Secondary Certificate (NSSC) curricu-lum. The chapter reflects on the influence of learner-centred education in the Namibian curriculum, the challenges and suc-cesses of ESD integration in the biology curriculum and how ESD has potential to strengthen and expand policies on learn-er-centred education, helping to translate them into practices.
- Full Text:
- Date Issued: 2017
- Authors: Tshiningayamwe, Sirrka
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/436223 , vital:73250 , ISBN 978-3-319-45989-9 , https://doi.org/10.1007/978-3-319-45989-9_8
- Description: As a response to the United Nations Decade of Education for Sustainable Development, Namibia has incorporated Educa-tion for Sustainable Development (ESD) into its education poli-cy. There has thus been a growing recognition of the signifi-cance of ESD across the school curriculum. However, of the various subjects taught in secondary schools, science sub-jects (especially biology) are often perceived as subjects that can make a significant contribution to ESD. Drawing on re-search that was conducted at three schools in Windhoek, this chapter will comment critically on the uptake of ESD in the Bi-ology Namibian Senior Secondary Certificate (NSSC) curricu-lum. The chapter reflects on the influence of learner-centred education in the Namibian curriculum, the challenges and suc-cesses of ESD integration in the biology curriculum and how ESD has potential to strengthen and expand policies on learn-er-centred education, helping to translate them into practices.
- Full Text:
- Date Issued: 2017
Estimating δ15N fractionation and adjusting the lipid correction equation using Southern African freshwater fishes
- Taylor, Geraldine C, Hill, Jaclyn M, Jackson, Michelle C, Peel, Richard A, Weyl, Olaf L F
- Authors: Taylor, Geraldine C , Hill, Jaclyn M , Jackson, Michelle C , Peel, Richard A , Weyl, Olaf L F
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69124 , vital:29392 , https://0-doi.org.wam.seals.ac.za/10.1371/journal.pone.0178047
- Description: Stable isotope analysis is an important tool for characterising food web structure; however, interpretation of isotope data can often be flawed. For instance, lipid normalisation and trophic fractionation values are often assumed to be constant, but can vary considerably between ecosystems, species and tissues. Here, previously determined lipid normalisation equations and trophic fractionation values were re-evaluated using freshwater fish species from three rivers in the Upper Zambezian floodplain ecoregion in southern Africa. The parameters commonly used in lipid normalisation equations were not correct for the 18 model species (new D and I parameters were estimated as D = 4.46‰ [95% CI: 2.62, 4.85] and constant I = 0 [95% CI: 0, 0.17]). We suggest that future isotopic analyses on freshwater fishes use our new values if the species under consideration do not have a high lipid content in their white muscle tissue. Nitrogen fractionation values varied between species and river basin; however, the average value closely matched that calculated in previous studies on other species (δ15N fractionation factor of 3.37 ± 1.30 ‰). Here we have highlighted the need to treat stable isotope data correctly in food web studies to avoid misinterpretation of the data.
- Full Text:
- Date Issued: 2017
- Authors: Taylor, Geraldine C , Hill, Jaclyn M , Jackson, Michelle C , Peel, Richard A , Weyl, Olaf L F
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69124 , vital:29392 , https://0-doi.org.wam.seals.ac.za/10.1371/journal.pone.0178047
- Description: Stable isotope analysis is an important tool for characterising food web structure; however, interpretation of isotope data can often be flawed. For instance, lipid normalisation and trophic fractionation values are often assumed to be constant, but can vary considerably between ecosystems, species and tissues. Here, previously determined lipid normalisation equations and trophic fractionation values were re-evaluated using freshwater fish species from three rivers in the Upper Zambezian floodplain ecoregion in southern Africa. The parameters commonly used in lipid normalisation equations were not correct for the 18 model species (new D and I parameters were estimated as D = 4.46‰ [95% CI: 2.62, 4.85] and constant I = 0 [95% CI: 0, 0.17]). We suggest that future isotopic analyses on freshwater fishes use our new values if the species under consideration do not have a high lipid content in their white muscle tissue. Nitrogen fractionation values varied between species and river basin; however, the average value closely matched that calculated in previous studies on other species (δ15N fractionation factor of 3.37 ± 1.30 ‰). Here we have highlighted the need to treat stable isotope data correctly in food web studies to avoid misinterpretation of the data.
- Full Text:
- Date Issued: 2017