The last two remaining populations of the critically endangered estuarine pipefish are inbred and not genetically distinct
- Weiss, Sven-Erick, Emami-Khoyi, Arsalan, Kaiser, Horst, Cowley, Paul D, James, Nicola C, Jansen van Vuuren, Bettine, Whitfield, Alan K, Teske, Peter R
- Authors: Weiss, Sven-Erick , Emami-Khoyi, Arsalan , Kaiser, Horst , Cowley, Paul D , James, Nicola C , Jansen van Vuuren, Bettine , Whitfield, Alan K , Teske, Peter R
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445101 , vital:74347 , https://doi.org/10.3389/fmars.2021.756595
- Description: Temporary wetland ecosystems are common in arid and semi‐arid envi-ronments, and are inhabited by diverse invertebrate communities. Little is known about the dynamics of genetic connectivity in the geograph-ically scattered populations of these wetland specialists. The current study investigated the spatial genetic structure and dispersal history of a recently described calanoid copepod, Lovenula raynerae, reported from temporary wetlands in the Eastern Cape province of South Africa. We tested whether the species represents a single, well-connected population or comprises different regional genetic groups, some of which may be rare or endangered.
- Full Text:
- Date Issued: 2022
- Authors: Weiss, Sven-Erick , Emami-Khoyi, Arsalan , Kaiser, Horst , Cowley, Paul D , James, Nicola C , Jansen van Vuuren, Bettine , Whitfield, Alan K , Teske, Peter R
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445101 , vital:74347 , https://doi.org/10.3389/fmars.2021.756595
- Description: Temporary wetland ecosystems are common in arid and semi‐arid envi-ronments, and are inhabited by diverse invertebrate communities. Little is known about the dynamics of genetic connectivity in the geograph-ically scattered populations of these wetland specialists. The current study investigated the spatial genetic structure and dispersal history of a recently described calanoid copepod, Lovenula raynerae, reported from temporary wetlands in the Eastern Cape province of South Africa. We tested whether the species represents a single, well-connected population or comprises different regional genetic groups, some of which may be rare or endangered.
- Full Text:
- Date Issued: 2022
The Mbira of the Ndau: Mozambique and Zimbabwe in 1972
- Authors: Tracey, Andrew
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481764 , vital:78583 , https://doi.org/10.21504/ajhece.v1i1.2481
- Description: The article, arising from research done in 1972, follows on the author’s series of analyses of the instrumental music of the Shona and Sena peoples of the Zambezi Valley. The analyses in this article focus on the relatively unknown mbira of the Ndau. The article describes its hexatonic note layout, highly variable tunings, and its variations among the Ndau-and Shangana-speaking groups in Southeast Zimbabwe and adjacent regions of Mozambique and South Africa. It includes the historical effect of the Shangana invasion of the nineteenth century into Mozambique. The article further discusses the transcription of the mbira’s music, in staff or the author’s own tablature, with detailed description of the latter. It compares Ndau with Shona concepts of ownership of songs, the practice of kubempa as used by Ndau travelling musicians and the difficulties of working in pre-independence Mozambique. The article presents songs in tablature, some by Bonisa Sithole, the author’s field assistant.
- Full Text:
- Date Issued: 2022
- Authors: Tracey, Andrew
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/481764 , vital:78583 , https://doi.org/10.21504/ajhece.v1i1.2481
- Description: The article, arising from research done in 1972, follows on the author’s series of analyses of the instrumental music of the Shona and Sena peoples of the Zambezi Valley. The analyses in this article focus on the relatively unknown mbira of the Ndau. The article describes its hexatonic note layout, highly variable tunings, and its variations among the Ndau-and Shangana-speaking groups in Southeast Zimbabwe and adjacent regions of Mozambique and South Africa. It includes the historical effect of the Shangana invasion of the nineteenth century into Mozambique. The article further discusses the transcription of the mbira’s music, in staff or the author’s own tablature, with detailed description of the latter. It compares Ndau with Shona concepts of ownership of songs, the practice of kubempa as used by Ndau travelling musicians and the difficulties of working in pre-independence Mozambique. The article presents songs in tablature, some by Bonisa Sithole, the author’s field assistant.
- Full Text:
- Date Issued: 2022
Antiviral drug discovery: preparing for the next pandemic
- Adamson, Catherine S, Chibale, Kelly, Goss, Rebecca J M, Jaspars, Marcel, Newman, David J, Dorrington, Rosemary A
- Authors: Adamson, Catherine S , Chibale, Kelly , Goss, Rebecca J M , Jaspars, Marcel , Newman, David J , Dorrington, Rosemary A
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/177499 , vital:42827 , DOI: 10.1039/d0cs01118e
- Description: Clinically approved antiviral drugs are currently available for only 10 of the more than 220 viruses known to infect humans. The SARS-CoV-2 outbreak has exposed the critical need for compounds that can be rapidly mobilised for the treatment of re-emerging or emerging viral diseases, while vaccine development is underway. We review the current status of antiviral therapies focusing on RNA viruses, highlighting strategies for antiviral drug discovery and discuss the challenges, solutions and options to accelerate drug discovery efforts.
- Full Text:
- Date Issued: 2021
- Authors: Adamson, Catherine S , Chibale, Kelly , Goss, Rebecca J M , Jaspars, Marcel , Newman, David J , Dorrington, Rosemary A
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/177499 , vital:42827 , DOI: 10.1039/d0cs01118e
- Description: Clinically approved antiviral drugs are currently available for only 10 of the more than 220 viruses known to infect humans. The SARS-CoV-2 outbreak has exposed the critical need for compounds that can be rapidly mobilised for the treatment of re-emerging or emerging viral diseases, while vaccine development is underway. We review the current status of antiviral therapies focusing on RNA viruses, highlighting strategies for antiviral drug discovery and discuss the challenges, solutions and options to accelerate drug discovery efforts.
- Full Text:
- Date Issued: 2021
Farmer-led institutional innovations in managing smallholder irrigation schemes in KwaZulu-Natal and Eastern Cape Provinces, South Africa
- Phakathi, Sandile, Sinyolo, Sikhulumile, Marire, Juniours, Fraser, Gavin C G
- Authors: Phakathi, Sandile , Sinyolo, Sikhulumile , Marire, Juniours , Fraser, Gavin C G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/471478 , vital:77457 , https://doi.org/10.1016/j.agwat.2021.106780
- Description: Farmer-led institutional innovations have been touted as the key to improving the management of water resources in irrigation schemes. However, little is known about them in South Africa. This study documents institutional innovations by 28 farmer groups located on four irrigation schemes in KwaZulu-Natal and Eastern Cape provinces, South Africa. Induced institutional innovation theory, Ostrom’s eight design principles, and thematic analysis of interview transcripts were used to analyse the data. The study results show that 21 groups engaged in institutional innovations, indicating high levels of farmer-led innovative activity among these irrigators. Examples of innovations include, among others, the introduction of a secret voting system to improve participation of marginalised people in decision-making processes, designing daily rotation rosters to reduce conflicts, as well as using an attendance register for participation in group activities, and rewarding members according to their participation levels.
- Full Text:
- Date Issued: 2021
- Authors: Phakathi, Sandile , Sinyolo, Sikhulumile , Marire, Juniours , Fraser, Gavin C G
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/471478 , vital:77457 , https://doi.org/10.1016/j.agwat.2021.106780
- Description: Farmer-led institutional innovations have been touted as the key to improving the management of water resources in irrigation schemes. However, little is known about them in South Africa. This study documents institutional innovations by 28 farmer groups located on four irrigation schemes in KwaZulu-Natal and Eastern Cape provinces, South Africa. Induced institutional innovation theory, Ostrom’s eight design principles, and thematic analysis of interview transcripts were used to analyse the data. The study results show that 21 groups engaged in institutional innovations, indicating high levels of farmer-led innovative activity among these irrigators. Examples of innovations include, among others, the introduction of a secret voting system to improve participation of marginalised people in decision-making processes, designing daily rotation rosters to reduce conflicts, as well as using an attendance register for participation in group activities, and rewarding members according to their participation levels.
- Full Text:
- Date Issued: 2021
Implementing a Content-Based Routing Framework for Application Integration on to Teleweaver Application Server
- Ngwenya, Sikhumbuzo, Shibeshi, Zelalem S, Terzoli, Alfredo
- Authors: Ngwenya, Sikhumbuzo , Shibeshi, Zelalem S , Terzoli, Alfredo
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430580 , vital:72701 , https://ieeexplore.ieee.org/abstract/document/9576969
- Description: This paper presents an architectural overview of content-based dynam-ic routing for integrating applications on to an application server named TeleWeaver, a middleware platform developed within Siyakhula Living Lab (SLL). SLL is an ICT4D project in the Eastern Cape Province of South Africa. TeleWeaver was created as a mediation layer between software systems developed for use by beneficiaries of the Siyakhula Living Lab. The main challenge with these disparate systems was that they had unnecessary, redundant components; TeleWeaver acts as a common platform that suits the development of many services such as eGovernment, eHealth, and eJudiciary.
- Full Text:
- Date Issued: 2021
- Authors: Ngwenya, Sikhumbuzo , Shibeshi, Zelalem S , Terzoli, Alfredo
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430580 , vital:72701 , https://ieeexplore.ieee.org/abstract/document/9576969
- Description: This paper presents an architectural overview of content-based dynam-ic routing for integrating applications on to an application server named TeleWeaver, a middleware platform developed within Siyakhula Living Lab (SLL). SLL is an ICT4D project in the Eastern Cape Province of South Africa. TeleWeaver was created as a mediation layer between software systems developed for use by beneficiaries of the Siyakhula Living Lab. The main challenge with these disparate systems was that they had unnecessary, redundant components; TeleWeaver acts as a common platform that suits the development of many services such as eGovernment, eHealth, and eJudiciary.
- Full Text:
- Date Issued: 2021
Implications of static and dynamic effects of economic integration for investment inflows and outflows using theories on industrial location: A theoretical debate
- Authors: Mutambara, Tsitsi E
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473143 , vital:77610 , https://ijbel.com/previous-issues/april-june-and-august-2021/vol-24-august-2021-issue-6/
- Description: Both the static and dynamic effects of economic integration have implications for investment inflows into a regional group, as well as relocation of investment by firms already domiciled in the regional group. Therefore, economic integration theory has become increasingly concerned about the locational effects of economic integration arrangements, thus giving rise to the growing interest by trade theorists in the importance of geography. New models of trade which incorporate factor mobility, external economies of scale and product competition, have established the importance of location in the analysis of the effects of economic integration arrangements. This research article therefore seeks to examine the implications of economic integration for industry location given the various theoretical debates with regard to locational choices of industries. This is done by reviewing theoretical arguments based on the Traditional theory of industrial location, the Marshallian theory, the theory of New economic geography, Weber’s theory and Dunning’s ownership, location and internalisation (OLI) theory. Arguments are thus presented to illustrate and explain how the static and dynamic effects of economic integration motivate industry location by creating the locational factors which the respective industry location theories present as key determinants for industry location. By examining the interplay between the key locational factors in the various theories and the static and dynamic effect of economic integration, this study shows that by viewing the theories of industrial location theories separately, each theory alone cannot answer adequately the question of industrial location and even agglomeration, despite highlighting and clarifying relevant factors. Therefore, the various theories must be integrated in order to understand the dynamics with which economic integration has implications for investment flows.
- Full Text:
- Date Issued: 2021
- Authors: Mutambara, Tsitsi E
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473143 , vital:77610 , https://ijbel.com/previous-issues/april-june-and-august-2021/vol-24-august-2021-issue-6/
- Description: Both the static and dynamic effects of economic integration have implications for investment inflows into a regional group, as well as relocation of investment by firms already domiciled in the regional group. Therefore, economic integration theory has become increasingly concerned about the locational effects of economic integration arrangements, thus giving rise to the growing interest by trade theorists in the importance of geography. New models of trade which incorporate factor mobility, external economies of scale and product competition, have established the importance of location in the analysis of the effects of economic integration arrangements. This research article therefore seeks to examine the implications of economic integration for industry location given the various theoretical debates with regard to locational choices of industries. This is done by reviewing theoretical arguments based on the Traditional theory of industrial location, the Marshallian theory, the theory of New economic geography, Weber’s theory and Dunning’s ownership, location and internalisation (OLI) theory. Arguments are thus presented to illustrate and explain how the static and dynamic effects of economic integration motivate industry location by creating the locational factors which the respective industry location theories present as key determinants for industry location. By examining the interplay between the key locational factors in the various theories and the static and dynamic effect of economic integration, this study shows that by viewing the theories of industrial location theories separately, each theory alone cannot answer adequately the question of industrial location and even agglomeration, despite highlighting and clarifying relevant factors. Therefore, the various theories must be integrated in order to understand the dynamics with which economic integration has implications for investment flows.
- Full Text:
- Date Issued: 2021
Prevalence and factors associated with suicidal ideation amongst college students in the Nelson Mandela Bay Municipality, South Africa
- Adeyinka A. Alabi, ROlawumi K. Oladimeji, Oladele V. Adeniyi
- Authors: Adeyinka A. Alabi , ROlawumi K. Oladimeji , Oladele V. Adeniyi
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3337 , vital:43315 , https://doi.org/10.4102/safp.v63i1.5195
- Description: Background: Suicidal behaviour amongst college students constitutes a significant social and public health problem globally. This study determined the prevalence and associated factors of suicidal ideation amongst students of higher education in the Nelson Mandela Bay Municipality (NMBM), South Africa. Methods: In this institution-based cross-sectional study, a multistage cluster sampling of 826 participants, drawn from a college in NMBM, was conducted from January to March 2020. Data were collected with a standardised self-administered questionnaire. Multivariable logistic regression analysis was used to identify the factors associated with suicidal ideation. Results: Participants’ ages ranged from 18 to 24 years, with a mean age of 20.49 years (standard deviation, 1.88 years). The lifetime prevalence of suicidal ideation and plans in the preceding 12 months were 24.5% and 9.6%, respectively. The odds of suicidal ideation were higher in students who experienced bullying (adjusted odds ratio [AOR], 1.89; 95% confidence interval [CI], 1.35–2.65), mental illness (AOR, 1.89; 95% CI, 1.35–2.65), a history of sexual assault (AOR, 2.50; 95% CI, 1.20–5.21) and experience of sexual assault by or to a close family member (AOR, 1.69; 95% CI, 1.01–2.82). Underlying chronic illness was associated with a twofold risk for suicidal ideation in both sexes. Conclusion: About a quarter of the students sampled at the college had experienced suicidal ideation and some had had suicidal plans in the preceding 12 months. Screening for the identified risk factors amongst the student population coupled with prompt interventions would mitigate the risk of suicide in the study population. Keywords: suicidal behaviour; suicidal plans; higher education; students; South Africa.
- Full Text:
- Date Issued: 2021
- Authors: Adeyinka A. Alabi , ROlawumi K. Oladimeji , Oladele V. Adeniyi
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3337 , vital:43315 , https://doi.org/10.4102/safp.v63i1.5195
- Description: Background: Suicidal behaviour amongst college students constitutes a significant social and public health problem globally. This study determined the prevalence and associated factors of suicidal ideation amongst students of higher education in the Nelson Mandela Bay Municipality (NMBM), South Africa. Methods: In this institution-based cross-sectional study, a multistage cluster sampling of 826 participants, drawn from a college in NMBM, was conducted from January to March 2020. Data were collected with a standardised self-administered questionnaire. Multivariable logistic regression analysis was used to identify the factors associated with suicidal ideation. Results: Participants’ ages ranged from 18 to 24 years, with a mean age of 20.49 years (standard deviation, 1.88 years). The lifetime prevalence of suicidal ideation and plans in the preceding 12 months were 24.5% and 9.6%, respectively. The odds of suicidal ideation were higher in students who experienced bullying (adjusted odds ratio [AOR], 1.89; 95% confidence interval [CI], 1.35–2.65), mental illness (AOR, 1.89; 95% CI, 1.35–2.65), a history of sexual assault (AOR, 2.50; 95% CI, 1.20–5.21) and experience of sexual assault by or to a close family member (AOR, 1.69; 95% CI, 1.01–2.82). Underlying chronic illness was associated with a twofold risk for suicidal ideation in both sexes. Conclusion: About a quarter of the students sampled at the college had experienced suicidal ideation and some had had suicidal plans in the preceding 12 months. Screening for the identified risk factors amongst the student population coupled with prompt interventions would mitigate the risk of suicide in the study population. Keywords: suicidal behaviour; suicidal plans; higher education; students; South Africa.
- Full Text:
- Date Issued: 2021
Prey and predator density‐dependent interactions under different water volumes
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Sentis, Arnaud, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Sentis, Arnaud , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466957 , vital:76802 , https://doi.org/10.1002/ece3.7503
- Description: Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modeling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator–prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator–predator interference effects.
- Full Text:
- Date Issued: 2021
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Sentis, Arnaud , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466957 , vital:76802 , https://doi.org/10.1002/ece3.7503
- Description: Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modeling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator–prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator–predator interference effects.
- Full Text:
- Date Issued: 2021
Specialty Grand Challenges in Urban Agriculture: Ecological and Social Approaches to Sustainability Transformations
- Zimmerer, Karl S, Bell, Martha G, Chirisa, Innocent, Duvall, Chris S, Egerer, Monika, Hung, Po-Yi, Lerner, Amy M, Shackleton, Charlie M, Ward, James David, Yacamán Ochoa, Carolina
- Authors: Zimmerer, Karl S , Bell, Martha G , Chirisa, Innocent , Duvall, Chris S , Egerer, Monika , Hung, Po-Yi , Lerner, Amy M , Shackleton, Charlie M , Ward, James David , Yacamán Ochoa, Carolina
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175779 , vital:42623 , https://doi.org/10.3389/fsufs.2021.668561
- Description: This synopsis of the Grand Challenges of Urban Agriculture (UA) is framed by the urgent need to understand and strengthen the expanding yet highly diverse roles of UA amid rapid global urbanization, failures of predominant food systems, and crises in systems of physical and mental health. More than half of humanity lives in cities today and by 2030 this is projected to grow to 60.4 percent, ~5 billion people (UN Habitat, 2020). More than 90 percent of urban demographic increase is anticipated to take place in the developing world.
- Full Text:
- Date Issued: 2021
- Authors: Zimmerer, Karl S , Bell, Martha G , Chirisa, Innocent , Duvall, Chris S , Egerer, Monika , Hung, Po-Yi , Lerner, Amy M , Shackleton, Charlie M , Ward, James David , Yacamán Ochoa, Carolina
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175779 , vital:42623 , https://doi.org/10.3389/fsufs.2021.668561
- Description: This synopsis of the Grand Challenges of Urban Agriculture (UA) is framed by the urgent need to understand and strengthen the expanding yet highly diverse roles of UA amid rapid global urbanization, failures of predominant food systems, and crises in systems of physical and mental health. More than half of humanity lives in cities today and by 2030 this is projected to grow to 60.4 percent, ~5 billion people (UN Habitat, 2020). More than 90 percent of urban demographic increase is anticipated to take place in the developing world.
- Full Text:
- Date Issued: 2021
The polyphagous shot hole borer beetle: current status of a perfect invader in South Africa
- Van Rooyen, Elmar, Paap, Trudy, De Beer, Wilhelm, Townsend, Garyn, Fell, Shawn, Nel, Wilma J, Morgan, Seamus, Hill, Martin P, Gonzalez, Allan, Roets, Francois
- Authors: Van Rooyen, Elmar , Paap, Trudy , De Beer, Wilhelm , Townsend, Garyn , Fell, Shawn , Nel, Wilma J , Morgan, Seamus , Hill, Martin P , Gonzalez, Allan , Roets, Francois
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480828 , vital:78480 , https://hdl.handle.net/10520/ejc-sajsci-v117-n11-a13
- Description: The polyphagous shot hole borer (PSHB) beetle is a recent invader in South Africa. Together with its fungal symbiont, Fusarium euwallaceae, it can rapidly kill highly susceptible host plants. Its impact is most profound in urban areas, but it has also been found infesting impor tant forestry, agricultural crop and native species. Since its first detection in 2012, PSHB has spread to all but one province in the country. The beetle-fungus complex has several biological traits that enhance its anthropogenically mediated dispersal, establishment and survival in novel environments - factors that have likely facilitated its rapid spread across the country. We review the history of the PSHB invasion in South Africa, its taxonomic status and the reasons for its rapid spread. We highlight its potential impact and challenges for its management. Finally, we provide an updated distribution map and list of confirmed host plants in South Africa. Of the 130 plant species identified as hosts, 48 of these (19 indigenous and 29 introduced) are reproductive hosts able to maintain breeding PSHB populations. These reproductive hosts may succumb to beetle infestations and act as 'pest-amplifiers'. The economic impact on urban forests, plantation forestry and agricultural crops may be severe, but the ecological impact of PSHB invasion in native ecosystems should not be underestimated.
- Full Text:
- Date Issued: 2021
- Authors: Van Rooyen, Elmar , Paap, Trudy , De Beer, Wilhelm , Townsend, Garyn , Fell, Shawn , Nel, Wilma J , Morgan, Seamus , Hill, Martin P , Gonzalez, Allan , Roets, Francois
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/480828 , vital:78480 , https://hdl.handle.net/10520/ejc-sajsci-v117-n11-a13
- Description: The polyphagous shot hole borer (PSHB) beetle is a recent invader in South Africa. Together with its fungal symbiont, Fusarium euwallaceae, it can rapidly kill highly susceptible host plants. Its impact is most profound in urban areas, but it has also been found infesting impor tant forestry, agricultural crop and native species. Since its first detection in 2012, PSHB has spread to all but one province in the country. The beetle-fungus complex has several biological traits that enhance its anthropogenically mediated dispersal, establishment and survival in novel environments - factors that have likely facilitated its rapid spread across the country. We review the history of the PSHB invasion in South Africa, its taxonomic status and the reasons for its rapid spread. We highlight its potential impact and challenges for its management. Finally, we provide an updated distribution map and list of confirmed host plants in South Africa. Of the 130 plant species identified as hosts, 48 of these (19 indigenous and 29 introduced) are reproductive hosts able to maintain breeding PSHB populations. These reproductive hosts may succumb to beetle infestations and act as 'pest-amplifiers'. The economic impact on urban forests, plantation forestry and agricultural crops may be severe, but the ecological impact of PSHB invasion in native ecosystems should not be underestimated.
- Full Text:
- Date Issued: 2021
Application of quality by design principles for optimizing process variables of Extrusion and Spheronization of a Captopril Pellet Formulation:
- Veerubhotla, Krishna, Walker, Roderick B
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
- Full Text:
- Date Issued: 2020
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/178312 , vital:40098 , DOI: 10.36468/pharmaceutical-sciences.624
- Description: Product development using quality by design is a proactive and risk-based approach that shifts the manufacturing process from empirical to science-based. Risk assessment was performed to identify and analyse risk areas for the manufacture of captopril pellets. Twelve experimental runs were performed using a Plackett-Burman screening design. Pareto plots revealed the effect of formulation and process variables on the responses monitored and facilitated the identification of the most critical parameters for optimization of the formulation. A response surface methodology approach in conjunction with a central composite design was used to optimize the Eudragit® RL 30D (15-30 ml), microcrystalline cellulose (20-40 % w/w), sodium starch glycolate (2-5 % w/w) and spheronizer speed (650-1050 rpm).
- Full Text:
- Date Issued: 2020
Benthic diatom-based indices and isotopic biomonitoring of nitrogen pollution in a warm temperate Austral river system
- Dalu, Tatenda, Cuthbert, Ross N, Taylor, Jonathan C, Magoro, Mandla L, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
- Authors: Dalu, Tatenda , Cuthbert, Ross N , Taylor, Jonathan C , Magoro, Mandla L , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/466917 , vital:76798 , https://doi.org/10.1016/j.scitotenv.2020.142452
- Description: Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables.
- Full Text:
- Date Issued: 2020
Climate modelling suggests a review of the legal status of Brazilian pepper Schinus terebinthifolia in South Africa is required:
- Martin, Grant D, Magengelele, Nwabisa L, Paterson, Iain D, Sutton, Guy F
- Authors: Martin, Grant D , Magengelele, Nwabisa L , Paterson, Iain D , Sutton, Guy F
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148606 , vital:38754 , https://doi.org/10.1016/j.sajb.2020.04.019
- Description: Brazilian pepper (Schinus terebinthifolia) is a tree native to subtropical South America that was introduced into South Africa in the early 1900s as an ornamental plant. The tree has since escaped cultivation and has invaded ruderal and pristine habitats along the eastern coast of South Africa. Brazilian Pepper is also one of the most problematic invasive alien plants in Florida, USA. We modelled the climatically suitable area for this species in South Africa using MaxEnt, with five distinct datasets: incorporating both the native and the invaded range of the species, as well as different backgrounds.
- Full Text:
- Date Issued: 2020
- Authors: Martin, Grant D , Magengelele, Nwabisa L , Paterson, Iain D , Sutton, Guy F
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148606 , vital:38754 , https://doi.org/10.1016/j.sajb.2020.04.019
- Description: Brazilian pepper (Schinus terebinthifolia) is a tree native to subtropical South America that was introduced into South Africa in the early 1900s as an ornamental plant. The tree has since escaped cultivation and has invaded ruderal and pristine habitats along the eastern coast of South Africa. Brazilian Pepper is also one of the most problematic invasive alien plants in Florida, USA. We modelled the climatically suitable area for this species in South Africa using MaxEnt, with five distinct datasets: incorporating both the native and the invaded range of the species, as well as different backgrounds.
- Full Text:
- Date Issued: 2020
Common dolphin Delphinus delphis occurrence off the Wild Coast of South Africa
- Caputo, Michelle, Froneman, P William, Plön, Stephanie
- Authors: Caputo, Michelle , Froneman, P William , Plön, Stephanie
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467255 , vital:76845 , https://doi.org/10.2989/1814232X.2020.1841676
- Description: Despite their typical large group sizes, limited research exists on the occurrence of common dolphins Delphinus delphis because of the pelagic, offshore nature of this species and the lack of barriers to their movement in this environment. The main purpose of our study was to investigate the occurrence of common dolphins off the Wild Coast of South Africa (western Indian Ocean) and whether spatiotemporal and environmental conditions affected their encounter rate, relative abundance and mean group size. The annual sardine run in this region, during austral winter (May to July), is considered a main driver of dolphin occurrence; however, our boat-based surveys over the period 2014–2016 indicated that common dolphins occur and feed in this area outside of this time-frame. In terms of environmental factors, the largest group (∼1 250 animals) was found in the deepest waters. Additionally, at Hluleka, dolphins were observed primarily feeding, which could suggest that this coastal area is highly productive. As common dolphin distribution is thought to be correlated with prey distribution, our findings suggest that sufficient prey exists along the Wild Coast both during and outside the annual sardine run to sustain large groups of the dolphins and that their presence in the area is not solely a function of the sardine run.
- Full Text:
- Date Issued: 2020
- Authors: Caputo, Michelle , Froneman, P William , Plön, Stephanie
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467255 , vital:76845 , https://doi.org/10.2989/1814232X.2020.1841676
- Description: Despite their typical large group sizes, limited research exists on the occurrence of common dolphins Delphinus delphis because of the pelagic, offshore nature of this species and the lack of barriers to their movement in this environment. The main purpose of our study was to investigate the occurrence of common dolphins off the Wild Coast of South Africa (western Indian Ocean) and whether spatiotemporal and environmental conditions affected their encounter rate, relative abundance and mean group size. The annual sardine run in this region, during austral winter (May to July), is considered a main driver of dolphin occurrence; however, our boat-based surveys over the period 2014–2016 indicated that common dolphins occur and feed in this area outside of this time-frame. In terms of environmental factors, the largest group (∼1 250 animals) was found in the deepest waters. Additionally, at Hluleka, dolphins were observed primarily feeding, which could suggest that this coastal area is highly productive. As common dolphin distribution is thought to be correlated with prey distribution, our findings suggest that sufficient prey exists along the Wild Coast both during and outside the annual sardine run to sustain large groups of the dolphins and that their presence in the area is not solely a function of the sardine run.
- Full Text:
- Date Issued: 2020
Contributions of the pars lateralis, pars basilaris and femur to age estimations of the immature skeleton within a South African forensic setting:
- Thornton, Roxanne, Edkins, Adrienne L, Hutchinson, E F
- Authors: Thornton, Roxanne , Edkins, Adrienne L , Hutchinson, E F
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165451 , vital:41245 , https://0-doi.org.wam.seals.ac.za/10.1007/s00414-019-02143-9
- Description: Dental development and eruption sequences have prevailed as the gold standard in age estimations of previously unidentified immature individuals within a legal context. However, in the absence of the dentition, skeletal assessments have served as a frequently applied alternative. While various cranial and postcranial skeletal elements have been used in estimating age of the immature skeleton, little is known about the anthropometric value of the pars basilaris, pars lateralis and femur as skeletal age estimation tools. Thus, this study aimed to assess if these bones of the immature human skeleton were useful elements in estimating the age of prenatal and postnatal individuals. These bones were excised from the remains of 74 unclaimed human immature individuals and evaluated using traditional anthropometric methods. The study sample was sourced from the Johannesburg Forensic Pathology Services (JFPS) and the Johannesburg Forensic Paediatric Collection (JFPC), University of the Witwatersrand and subdivided into an early prenatal (younger than 30 gestational weeks); late prenatal (30 to 40 gestational weeks) and postnatal (birth to 7.5 months) age ranges.
- Full Text:
- Date Issued: 2020
- Authors: Thornton, Roxanne , Edkins, Adrienne L , Hutchinson, E F
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165451 , vital:41245 , https://0-doi.org.wam.seals.ac.za/10.1007/s00414-019-02143-9
- Description: Dental development and eruption sequences have prevailed as the gold standard in age estimations of previously unidentified immature individuals within a legal context. However, in the absence of the dentition, skeletal assessments have served as a frequently applied alternative. While various cranial and postcranial skeletal elements have been used in estimating age of the immature skeleton, little is known about the anthropometric value of the pars basilaris, pars lateralis and femur as skeletal age estimation tools. Thus, this study aimed to assess if these bones of the immature human skeleton were useful elements in estimating the age of prenatal and postnatal individuals. These bones were excised from the remains of 74 unclaimed human immature individuals and evaluated using traditional anthropometric methods. The study sample was sourced from the Johannesburg Forensic Pathology Services (JFPS) and the Johannesburg Forensic Paediatric Collection (JFPC), University of the Witwatersrand and subdivided into an early prenatal (younger than 30 gestational weeks); late prenatal (30 to 40 gestational weeks) and postnatal (birth to 7.5 months) age ranges.
- Full Text:
- Date Issued: 2020
Dataset of experimental and adaptive neuro-fuzzy inference system (ANFIS) model prediction of R600a/MWCNT nanolubricant in a vapour compression system
- Babarinde, T O, Akinlabi, S A, Madyira, D M, Ekundayo, F M, Adedeji, P A
- Authors: Babarinde, T O , Akinlabi, S A , Madyira, D M , Ekundayo, F M , Adedeji, P A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3248 , vital:43283 , https://doi.org/10.1016/j.dib.2020.106316
- Description: This research paper assessed the performance of R600a with the base lubricant and Multi-walled Carbon Nanotube (MWCNT) nanolubricant at steady state. It describes the instruments required for measurement of the data parameter and its uncertainties, steps involved in preparing and replacing the MWCNT nanolubricant concentration with base lubricant in vapour compression refrigeration. The system’s temperature data was collected at the components inlets and outlets. Pressure data was also registered at the compressor outlet and inlet. The data was captured at 27 °C ambient temperature at an interval of 30 min for 300 min. The experiment includes the experimental data collection, Adaptive Neuro-Fuzzy Inference System (ANFIS) training and testing dataset. The use of ANFIS model is explained in predicting the efficiency of MWCNT nanolubricant in a vapour compression refrigerator system. The ANFIS model also provides statistical output measures such as Root Mean Square Error (RMSE) and Mean Absolute Deviation (MAD), Mean Absolute Percentage Error (MAPE), and determination coefficient (R2). The data is useful and important for replacing MWCNT nanolubricant with base lubricant in a vapour compression refrigeration system for researchers in the specialisation of energy-efficient materials in refrigeration. The data present can be reused for vapour compression refrigeration systems simulation and modelling.
- Full Text:
- Date Issued: 2020
- Authors: Babarinde, T O , Akinlabi, S A , Madyira, D M , Ekundayo, F M , Adedeji, P A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3248 , vital:43283 , https://doi.org/10.1016/j.dib.2020.106316
- Description: This research paper assessed the performance of R600a with the base lubricant and Multi-walled Carbon Nanotube (MWCNT) nanolubricant at steady state. It describes the instruments required for measurement of the data parameter and its uncertainties, steps involved in preparing and replacing the MWCNT nanolubricant concentration with base lubricant in vapour compression refrigeration. The system’s temperature data was collected at the components inlets and outlets. Pressure data was also registered at the compressor outlet and inlet. The data was captured at 27 °C ambient temperature at an interval of 30 min for 300 min. The experiment includes the experimental data collection, Adaptive Neuro-Fuzzy Inference System (ANFIS) training and testing dataset. The use of ANFIS model is explained in predicting the efficiency of MWCNT nanolubricant in a vapour compression refrigerator system. The ANFIS model also provides statistical output measures such as Root Mean Square Error (RMSE) and Mean Absolute Deviation (MAD), Mean Absolute Percentage Error (MAPE), and determination coefficient (R2). The data is useful and important for replacing MWCNT nanolubricant with base lubricant in a vapour compression refrigeration system for researchers in the specialisation of energy-efficient materials in refrigeration. The data present can be reused for vapour compression refrigeration systems simulation and modelling.
- Full Text:
- Date Issued: 2020
Development of manganese phthalocyanine decorated with silver nanoparticles nanocomposite for improved electrocatalytic oxidation of hydrazine:
- Mpeta, Lekhetho S, Sen, Pinar, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Sen, Pinar , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148472 , vital:38742 , https://doi.org/10.1016/j.jelechem.2020.114173
- Description: In this study we report on the synthesis of tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl) phenoxy phthalocyaninato] manganese (III) chloride (MnPc). The MnPc was first used to modify a glassy carbon electrode, followed by the growth of silver nanoparticles (AgNPs) onto the MnPc modified electrode to form MnPc-AgNPs modified electrode. The modified electrode was characterized using cydic voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy. The modified MnPc-AgNPs electrode was employed for the detection of hydrazine. The MnPc-AgNPs gave better current responses for electrooxidation of hydrazine relative to MnPc and AgNPs, individually. The catalytic rate constant was 1.90 x 10(5 )M(-1) S-1, with the detection limit (LoD) of 2.42 pM (using 3 sigma notation), and sensitivity of 61.56 mu A mM(-1), for MnPc-AgNPs. (C) 2020 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2020
- Authors: Mpeta, Lekhetho S , Sen, Pinar , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148472 , vital:38742 , https://doi.org/10.1016/j.jelechem.2020.114173
- Description: In this study we report on the synthesis of tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl) phenoxy phthalocyaninato] manganese (III) chloride (MnPc). The MnPc was first used to modify a glassy carbon electrode, followed by the growth of silver nanoparticles (AgNPs) onto the MnPc modified electrode to form MnPc-AgNPs modified electrode. The modified electrode was characterized using cydic voltammetry, chronoamperometry, scanning electrochemical microscopy and electrochemical impedance spectroscopy. The modified MnPc-AgNPs electrode was employed for the detection of hydrazine. The MnPc-AgNPs gave better current responses for electrooxidation of hydrazine relative to MnPc and AgNPs, individually. The catalytic rate constant was 1.90 x 10(5 )M(-1) S-1, with the detection limit (LoD) of 2.42 pM (using 3 sigma notation), and sensitivity of 61.56 mu A mM(-1), for MnPc-AgNPs. (C) 2020 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2020
Dietary fatty acids of spiders reveal spatial and temporal variations in aquatic-terrestrial linkages
- Chari, Lenin D, Richoux, Nicole B, Moyo, Sydney, Villet, Martin H
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
- Authors: Chari, Lenin D , Richoux, Nicole B , Moyo, Sydney , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441919 , vital:73935 , https://doi.org/10.1016/j.fooweb.2020.e00152
- Description: Stream and riparian food webs can be strongly linked by inputs of aquatic emergent insect prey to terrestrial predators. However, quantifying these linkages and understanding how they vary in time and space is challenging. We investigated the dynamic width of a riverine trophic subsidy zone by determining the relationship between perpendicular distance from a river and dietary contributions of aquatic insect prey to web-building spiders' diets. To assess this relationship, riparian web-building spiders at two river sites were sampled during four seasons and analysed for the fatty acids 16:0, 16:1ω7 and 20:5ω3, their total ω3-fatty acid content and their ω3:ω6 ratio to evaluate trophic subsidies reaching them from an adjacent river. River-derived fatty acids generally declined with increased distance from the river, indicating a diffusion of aquatically derived subsidies into the riparian zone. While the river was only 16 m wide at its broadest, river-derived trophic subsidies were detected up to four times that distance from the river edge. Spiders at a downstream section of the river, characterised by generally higher emergence rates of aquatic insects, contained higher proportions of aquatic indicator fatty acids compared with spiders located upstream, where emergence rates were lower. Similarly, proportions of aquatic indicator fatty acids in spiders were lowest during winter when aquatic insect emergence rates were lowest. The fatty acid 20:5ω3 (eicosapentaenoic acid; EPA) held the best promise as a biomarker of aquatic-derived tropic subsidies and could be developed as a useful tool for riparian research and management.
- Full Text:
- Date Issued: 2020
Do spotted hyaenas outcompete the big cats in a small, enclosed system in South Africa?:
- Comley, Jessica, Joubert, Christoffel J, Mgqatsa, Nokubonga, Parker, Daniel M
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150099 , vital:38940 , doi:10.1111/jzo.12772
- Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (over 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati).
- Full Text:
- Date Issued: 2020
- Authors: Comley, Jessica , Joubert, Christoffel J , Mgqatsa, Nokubonga , Parker, Daniel M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150099 , vital:38940 , doi:10.1111/jzo.12772
- Description: Carnivores are adapted to kill, meaning sympatric carnivores can have particularly aggressive and harmful competitive interactions. The co‐existence of multiple carnivores in an ecosystem could be restricted by their similarity in ecological niches (e.g. dietary overlap); however, high prey abundances could facilitate their co‐existence. Although the development of small, enclosed reserves (over 400 km2) in South Africa has reduced human–carnivore conflict, these systems may increase the likelihood of carnivore intra‐guild competition due to the clumping of competing carnivores into these restricted spaces. Using carnivore scat and kill site analyses, we determined the dietary preferences and overlap of sympatric large carnivores in a small, enclosed reserve, Selati Game Reserve (Selati).
- Full Text:
- Date Issued: 2020
Examining intraspecific multiple predator effects across shifting predator sex ratios:
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020