The importance of long-term post-release studies in classical biological control: Insect–plant monitoring and public awareness of water hyacinth management (Pontederia crassipes) in Dique Los Sauces, Argentina
- Faltlhauser, Ana C, Jiménez, Nadia L, Righetti, Tomas, Visintin, Andrés M, Torrens, Javier, Salinas, Nicolás A, Mc Kay, Fernando, Hill, Martin P, Cordo, Hugo A, Sosa, Alejandro J
- Authors: Faltlhauser, Ana C , Jiménez, Nadia L , Righetti, Tomas , Visintin, Andrés M , Torrens, Javier , Salinas, Nicolás A , Mc Kay, Fernando , Hill, Martin P , Cordo, Hugo A , Sosa, Alejandro J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424828 , vital:72187 , xlink:href="https://doi.org/10.1111/eea.13355"
- Description: Several components of classical biological control (CBC) programmes are necessary to assess the success of the management strategy (e.g., post-release monitoring) and also help prevent reintroductions or resurgences of invasive species (e.g., public awareness). Water hyacinth, Pontederia (= Eichhornia) crassipes (Mart.) Solms (Pontederiaceae) is an aquatic plant naturally distributed in the north-eastern region of the Del Plata basin in Argentina. In the 1960s it was introduced into the Dique Los Sauces reservoir located outside of its native range in La Rioja Province, in western Argentina, where it became invasive. The natural enemy, Neochetina bruchi Hustache (Coleoptera: Curculionidae), was intentionally introduced in 1974 to control the weed. To assess the success of this CBC programme, a long-term post-release study was conducted. Between 1965 and 2023, we monitored plant coverage, estimated N. bruchi densities, and quantified the associated damage by reanalysing previously published data and incorporating new sampling. We also conducted an online survey to analyse public knowledge and perception about this programme. Water hyacinth coverage fluctuated from its first record in 1965 (maximum coverage 90%) until the control of germinated plants (coverage 0%) in 2018. The plant decline was accompanied by an increase in the weevil population. In our survey, out of 325 respondents only a small group of mostly middle-aged and elderly people knew that the restoration had been achieved through a management strategy and even fewer were aware of the biocontrol approach taken. Respondents who had a positive approach to biological control were more aware of the management plan than respondents who had neutral or negative opinions. Neochetina bruchi has played a key factor in the control of P. crassipes. The intrinsic dynamics of these populations, the dormant seed bank, and the lack of public awareness support the need for long post-release evaluations including outreach campaigns to make a sustainable successful management programme.
- Full Text:
- Date Issued: 2023
- Authors: Faltlhauser, Ana C , Jiménez, Nadia L , Righetti, Tomas , Visintin, Andrés M , Torrens, Javier , Salinas, Nicolás A , Mc Kay, Fernando , Hill, Martin P , Cordo, Hugo A , Sosa, Alejandro J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424828 , vital:72187 , xlink:href="https://doi.org/10.1111/eea.13355"
- Description: Several components of classical biological control (CBC) programmes are necessary to assess the success of the management strategy (e.g., post-release monitoring) and also help prevent reintroductions or resurgences of invasive species (e.g., public awareness). Water hyacinth, Pontederia (= Eichhornia) crassipes (Mart.) Solms (Pontederiaceae) is an aquatic plant naturally distributed in the north-eastern region of the Del Plata basin in Argentina. In the 1960s it was introduced into the Dique Los Sauces reservoir located outside of its native range in La Rioja Province, in western Argentina, where it became invasive. The natural enemy, Neochetina bruchi Hustache (Coleoptera: Curculionidae), was intentionally introduced in 1974 to control the weed. To assess the success of this CBC programme, a long-term post-release study was conducted. Between 1965 and 2023, we monitored plant coverage, estimated N. bruchi densities, and quantified the associated damage by reanalysing previously published data and incorporating new sampling. We also conducted an online survey to analyse public knowledge and perception about this programme. Water hyacinth coverage fluctuated from its first record in 1965 (maximum coverage 90%) until the control of germinated plants (coverage 0%) in 2018. The plant decline was accompanied by an increase in the weevil population. In our survey, out of 325 respondents only a small group of mostly middle-aged and elderly people knew that the restoration had been achieved through a management strategy and even fewer were aware of the biocontrol approach taken. Respondents who had a positive approach to biological control were more aware of the management plan than respondents who had neutral or negative opinions. Neochetina bruchi has played a key factor in the control of P. crassipes. The intrinsic dynamics of these populations, the dormant seed bank, and the lack of public awareness support the need for long post-release evaluations including outreach campaigns to make a sustainable successful management programme.
- Full Text:
- Date Issued: 2023
Synthesis, characterisation and evaluation of benzoxaborole-based hybrids as antiplasmodial agents
- Authors: Gumbo, Maureen
- Date: 2017
- Subjects: Malaria Chemotherapy , Antimalarials , Boron compounds , Drug resistance , Plasmodium falciparum , Drug development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59193 , vital:27456
- Description: Malaria is a mosquito-borne disease, which continues to pose a threat to the entire humanity. About 40% of the world population is estimated to be at risk of infections by malaria. Despite efforts undertaken by scientific community, government entities and international organizations, malaria is still rampant. The major problem is drug resistance, where the Plasmodium spp have over the past decades developed drug resistance against available drugs. In order to counter this problem, novel antimalarial drugs that are efficacious and with novel mode of action are of great necessity. Benzoxaborole derivatives have been shown to exhibit promising antimalarial activity against Plasmodium falciparum strains. Previous studies reported on the compounds such as 6-(2- (alkoxycarbonyl)pyrazinyl-5-oxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles, which showed good antimalarial activity against both W7 and 3D7 strains without significant toxicity. On the other hand, chloroquine (CQ) and cinnamic acids have a wide variety of biological activity including antimalarial activity. Herein, a hybridisation strategy was employed to synthesise new CQ-benzoxaborole and cinnamoyl-benzoxaborole hybrids. CQ-Benzoxaborole 2.12a-c and cinnamoylbenzoxaborole 2.11a-g hydrid molecules were synthesised in low to good yields. Their structural identities were confirmed using conventional spectroscopic techniques (1H and 13C NMR, and mass spectrometry). CQ-benzoxaborole compounds, however, showed instability, and only 2.12b was used for in vitro biological assay and showed activity comparable to CQ. Furthermore, in vitro biological assay revealed that compounds 2.11a-g poorly inhibited the growth of P. falciparum parasites. Interestingly, these compounds, however, exhibited satisfactory activity against Trypanosoma brucei with IC50 = 0.052 μM for compound 2.11g. The cell cytotoxicity assay of all final compounds confirmed that all CQ-benzoxaborole 2.12b and cinnamoyl-benzoxaborole 2.11a-g hybrids were non-toxic against HeLa cell lines. However, efforts to further expand the structure-activity relationship (SAR) of CQbenzoxaborole by increasing the length of the linker with one extra carbon (Scheme 2.10) were not possible as an important precursor 6-formylbenzoxaborole 2.29 could not be synthesized in sufficient yields. , Thesis (MSc) -- Faculty of Faculty of Science, Chemistry, 2017
- Full Text:
- Date Issued: 2017
- Authors: Gumbo, Maureen
- Date: 2017
- Subjects: Malaria Chemotherapy , Antimalarials , Boron compounds , Drug resistance , Plasmodium falciparum , Drug development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59193 , vital:27456
- Description: Malaria is a mosquito-borne disease, which continues to pose a threat to the entire humanity. About 40% of the world population is estimated to be at risk of infections by malaria. Despite efforts undertaken by scientific community, government entities and international organizations, malaria is still rampant. The major problem is drug resistance, where the Plasmodium spp have over the past decades developed drug resistance against available drugs. In order to counter this problem, novel antimalarial drugs that are efficacious and with novel mode of action are of great necessity. Benzoxaborole derivatives have been shown to exhibit promising antimalarial activity against Plasmodium falciparum strains. Previous studies reported on the compounds such as 6-(2- (alkoxycarbonyl)pyrazinyl-5-oxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles, which showed good antimalarial activity against both W7 and 3D7 strains without significant toxicity. On the other hand, chloroquine (CQ) and cinnamic acids have a wide variety of biological activity including antimalarial activity. Herein, a hybridisation strategy was employed to synthesise new CQ-benzoxaborole and cinnamoyl-benzoxaborole hybrids. CQ-Benzoxaborole 2.12a-c and cinnamoylbenzoxaborole 2.11a-g hydrid molecules were synthesised in low to good yields. Their structural identities were confirmed using conventional spectroscopic techniques (1H and 13C NMR, and mass spectrometry). CQ-benzoxaborole compounds, however, showed instability, and only 2.12b was used for in vitro biological assay and showed activity comparable to CQ. Furthermore, in vitro biological assay revealed that compounds 2.11a-g poorly inhibited the growth of P. falciparum parasites. Interestingly, these compounds, however, exhibited satisfactory activity against Trypanosoma brucei with IC50 = 0.052 μM for compound 2.11g. The cell cytotoxicity assay of all final compounds confirmed that all CQ-benzoxaborole 2.12b and cinnamoyl-benzoxaborole 2.11a-g hybrids were non-toxic against HeLa cell lines. However, efforts to further expand the structure-activity relationship (SAR) of CQbenzoxaborole by increasing the length of the linker with one extra carbon (Scheme 2.10) were not possible as an important precursor 6-formylbenzoxaborole 2.29 could not be synthesized in sufficient yields. , Thesis (MSc) -- Faculty of Faculty of Science, Chemistry, 2017
- Full Text:
- Date Issued: 2017
A chiral hemiporphyrazine derivative
- Wu, Yanping, Gai, Lizhi, Xiao, Xuqiong, Lu, Hua, Li, Zhifang, Mack, John, Harris, Jessica, Nyokong, Tebello, Shen, Zhen
- Authors: Wu, Yanping , Gai, Lizhi , Xiao, Xuqiong , Lu, Hua , Li, Zhifang , Mack, John , Harris, Jessica , Nyokong, Tebello , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240404 , vital:50831 , xlink:href="https://doi.org/10.1002/asia.201600754"
- Description: The synthesis of an optically active hemiporphyrazine with chiral binaphthyl substituents (1) is reported, providing the first example of the incorporation of an intrinsically chiral moiety into the macrocyclic core of a hemiporphyrazine analogue. A negative circular dichroism (CD) signal is observed in the 325–450 nm region of the CD spectrum of (S,S)-1, while mainly positive bands are observed in the 220–325 nm region. Mirror symmetry is observed across the entire wavelength range of the CD spectra of (R,R)-1 and (S,S)-1. An irreversible one-electron oxidation wave with an onset potential at 1.07 V is observed by cyclic voltammetry, along with a reversible one-electron reduction wave at −0.85 V. Density functional calculations reproduce the experimentally observed data and trends, and provide further insight into the nature of the electronic transitions.
- Full Text:
- Date Issued: 2016
- Authors: Wu, Yanping , Gai, Lizhi , Xiao, Xuqiong , Lu, Hua , Li, Zhifang , Mack, John , Harris, Jessica , Nyokong, Tebello , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240404 , vital:50831 , xlink:href="https://doi.org/10.1002/asia.201600754"
- Description: The synthesis of an optically active hemiporphyrazine with chiral binaphthyl substituents (1) is reported, providing the first example of the incorporation of an intrinsically chiral moiety into the macrocyclic core of a hemiporphyrazine analogue. A negative circular dichroism (CD) signal is observed in the 325–450 nm region of the CD spectrum of (S,S)-1, while mainly positive bands are observed in the 220–325 nm region. Mirror symmetry is observed across the entire wavelength range of the CD spectra of (R,R)-1 and (S,S)-1. An irreversible one-electron oxidation wave with an onset potential at 1.07 V is observed by cyclic voltammetry, along with a reversible one-electron reduction wave at −0.85 V. Density functional calculations reproduce the experimentally observed data and trends, and provide further insight into the nature of the electronic transitions.
- Full Text:
- Date Issued: 2016
A comparative physicochemical study of unsymmetrical indium phthalocyanines in the presence of magnetic nanoparticles or quantum dots
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
A critical appraisal of the ideology of monogamys influence on HIV epidemiology
- Kenyon, Chris R, Colebunders, Robert, Dlamini, Sipho S, Meulemans, Herman, Zondo, Sizwe
- Authors: Kenyon, Chris R , Colebunders, Robert , Dlamini, Sipho S , Meulemans, Herman , Zondo, Sizwe
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450541 , vital:74959 , xlink:href="10.12688/f1000research.14951.2"
- Description: The linked ideas that all members of society should only engage in monogamous relationships and that these should all be based on romantic love are decided outliers from a historical perspective. Despite this, there is a widespread contemporary belief that monogamy based on love is the most ethical and natural form of partnering for humans mononormativism. It has long been accepted that our values influence how we frame and interpret scientific questions. In the article we ask, using the example of mononormativism, how does an individual s sexual ethics influence how they pursue HIV epidemiology? Using a Social Intuitionalist theoretical framework, we argue that a be-lief in monogamy-as-normative has contributed to certain researchers dismissing the evidence that the generalized HIV epidemics in parts of Africa are due to higher rates of non-monogamy.
- Full Text:
- Date Issued: 2016
- Authors: Kenyon, Chris R , Colebunders, Robert , Dlamini, Sipho S , Meulemans, Herman , Zondo, Sizwe
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450541 , vital:74959 , xlink:href="10.12688/f1000research.14951.2"
- Description: The linked ideas that all members of society should only engage in monogamous relationships and that these should all be based on romantic love are decided outliers from a historical perspective. Despite this, there is a widespread contemporary belief that monogamy based on love is the most ethical and natural form of partnering for humans mononormativism. It has long been accepted that our values influence how we frame and interpret scientific questions. In the article we ask, using the example of mononormativism, how does an individual s sexual ethics influence how they pursue HIV epidemiology? Using a Social Intuitionalist theoretical framework, we argue that a be-lief in monogamy-as-normative has contributed to certain researchers dismissing the evidence that the generalized HIV epidemics in parts of Africa are due to higher rates of non-monogamy.
- Full Text:
- Date Issued: 2016
Acoustic biosensors
- Fogel, Ronen, Limson, Janice L, Seshia, Ashwin A
- Authors: Fogel, Ronen , Limson, Janice L , Seshia, Ashwin A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431648 , vital:72793 , xlink:href="https://doi.org/10.1042/EBC20150011"
- Description: Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors.
- Full Text:
- Date Issued: 2016
- Authors: Fogel, Ronen , Limson, Janice L , Seshia, Ashwin A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431648 , vital:72793 , xlink:href="https://doi.org/10.1042/EBC20150011"
- Description: Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors.
- Full Text:
- Date Issued: 2016
Aggregation control of robust water-soluble zinc (II) phthalocyanine-based photosensitizers
- Ikeuchi, Takuro, Mack, John, Nyokong, Tebello, Kobayashi, Nagao, Kimura, Mutsumi
- Authors: Ikeuchi, Takuro , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Kimura, Mutsumi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239709 , vital:50757 , xlink:href="https://doi.org/10.1021/acs.langmuir.6b03552"
- Description: A water-soluble zinc phthalocyanine (ZnPc) complex with four negatively charged electron-withdrawing sulfonic acid substituents at the nonperipheral positions (α-ZnTSPc) is found to have a high singlet oxygen (1O2) quantum yield and exhibits high photostability. The formation of aggregates is hindered and the highest occupied molecular orbital is significantly stabilized, making α-ZnTSPc potentially suitable for its use as a photosensitizer for photodynamic therapy and photoimmunotherapy. Atomic force microscopy (AFM) reveals that mixtures of the negatively charged α-ZnTSPc complex with a similar positively charged ZnPc were found to result in the self-assembly of one-dimensional accordion-like fibers. Supramolecular fibers can be formed in aqueous solutions through intermolecular electrostatic and donor–acceptor interactions between the two water-soluble ZnPcs.
- Full Text:
- Date Issued: 2016
- Authors: Ikeuchi, Takuro , Mack, John , Nyokong, Tebello , Kobayashi, Nagao , Kimura, Mutsumi
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239709 , vital:50757 , xlink:href="https://doi.org/10.1021/acs.langmuir.6b03552"
- Description: A water-soluble zinc phthalocyanine (ZnPc) complex with four negatively charged electron-withdrawing sulfonic acid substituents at the nonperipheral positions (α-ZnTSPc) is found to have a high singlet oxygen (1O2) quantum yield and exhibits high photostability. The formation of aggregates is hindered and the highest occupied molecular orbital is significantly stabilized, making α-ZnTSPc potentially suitable for its use as a photosensitizer for photodynamic therapy and photoimmunotherapy. Atomic force microscopy (AFM) reveals that mixtures of the negatively charged α-ZnTSPc complex with a similar positively charged ZnPc were found to result in the self-assembly of one-dimensional accordion-like fibers. Supramolecular fibers can be formed in aqueous solutions through intermolecular electrostatic and donor–acceptor interactions between the two water-soluble ZnPcs.
- Full Text:
- Date Issued: 2016
Allelopathic effects of Lantana camara on indigenous forest species in South Africa
- Ruwanza, Sheunesu, Shackleton, Charlie M
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182296 , vital:43818 , xlink:href="http://www.allelopathyjournal.org/?"
- Description: Lantana camara, is an invasive plant in South Africa and greatly influences the forest spp. In greenhouse, we evaluated the allelopathic effects of aqueous extracts of L. camara leaf, stem and root on 5-test species, (3-forest species viz., Acacia natalitia, Kiggalaria africana and Searsia crenata and 2-crops: Solanum lycopersicum and Lactuca sativa). Potential allelopathic compounds present in L. camara leaf, stem and root aqueous extracts were identified using gas chromatography mass spectrometry (GC-MS). The leaf, stem and root aqueous extracts of L. camara reduced the seed germination and seedling growth of all test species showing that L. camara aqueous extracts were deleterious to all test species. We identified 92 major volatile organic components in L. camara aqueous extracts. These compounds had the potential to inhibit the germination and seedling growth of test crops. The leaf, stem and root aqueous extracts of L. camara contained the allelopathic compounds that inhibited the germination and seedling growth of indigenous forest species and crop species.
- Full Text:
- Date Issued: 2016
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182296 , vital:43818 , xlink:href="http://www.allelopathyjournal.org/?"
- Description: Lantana camara, is an invasive plant in South Africa and greatly influences the forest spp. In greenhouse, we evaluated the allelopathic effects of aqueous extracts of L. camara leaf, stem and root on 5-test species, (3-forest species viz., Acacia natalitia, Kiggalaria africana and Searsia crenata and 2-crops: Solanum lycopersicum and Lactuca sativa). Potential allelopathic compounds present in L. camara leaf, stem and root aqueous extracts were identified using gas chromatography mass spectrometry (GC-MS). The leaf, stem and root aqueous extracts of L. camara reduced the seed germination and seedling growth of all test species showing that L. camara aqueous extracts were deleterious to all test species. We identified 92 major volatile organic components in L. camara aqueous extracts. These compounds had the potential to inhibit the germination and seedling growth of test crops. The leaf, stem and root aqueous extracts of L. camara contained the allelopathic compounds that inhibited the germination and seedling growth of indigenous forest species and crop species.
- Full Text:
- Date Issued: 2016
An analysis of grade 12 students' attitudes towards agriculture as a career choice in Nkonkobe municipality, Eastern Cape
- Authors: Ndema, Tenjiwe N
- Date: 2016
- Subjects: Career development -- South Africa , Agriculture -- Study and teaching -- South Africa -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26592 , vital:65661
- Description: In South Africa there is a perception that the youth, particularly black youth, lack interest in agriculture as a career. The youth are perceived to be more drawn to white collar jobs, because they believe that these jobs are more pleasant and better paying. The literature moreover suggests that the youth perceive agriculture as dirty work which is more appropriate for uneducated or illiterate people. The main aim of the research was to analyse Grade12 students’ attitudes towards agriculture as a career choice in Nkonkobe Municipality. Students from four high schools were interviewed using a structured questionnaire, and the total sample size was 100. Based on the results, about one third of students have a favorable perception of agriculture as a career choice, which is more than what had been expected based on the literature reviewed. Both students from non-agricultural schools and agricultural schools possess a positive attitude towards agriculture. They indicated that agriculture offers a lot of financial gain, is not necessarily associated with poverty, nor is agriculture widely regarded as a last resort for those who have failed in other careers. Moreover, they believe that agriculture is as important as other sectors. However, of those learners who indicated an intention to pursue agriculture as a career, only 1 % specifically wished to become a farmer. The others rather wanted professional careers within the agricultural sector, such as veterinarians, agricultural economists, and so forth. Their interest in agriculture as a career related in large measure to a desire to live in a rural area and work with their hands; however this did not extend to actual farming. , Thesis (M Agric) -- Faculty of Science and Agriculture, 2016
- Full Text:
- Date Issued: 2016
- Authors: Ndema, Tenjiwe N
- Date: 2016
- Subjects: Career development -- South Africa , Agriculture -- Study and teaching -- South Africa -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26592 , vital:65661
- Description: In South Africa there is a perception that the youth, particularly black youth, lack interest in agriculture as a career. The youth are perceived to be more drawn to white collar jobs, because they believe that these jobs are more pleasant and better paying. The literature moreover suggests that the youth perceive agriculture as dirty work which is more appropriate for uneducated or illiterate people. The main aim of the research was to analyse Grade12 students’ attitudes towards agriculture as a career choice in Nkonkobe Municipality. Students from four high schools were interviewed using a structured questionnaire, and the total sample size was 100. Based on the results, about one third of students have a favorable perception of agriculture as a career choice, which is more than what had been expected based on the literature reviewed. Both students from non-agricultural schools and agricultural schools possess a positive attitude towards agriculture. They indicated that agriculture offers a lot of financial gain, is not necessarily associated with poverty, nor is agriculture widely regarded as a last resort for those who have failed in other careers. Moreover, they believe that agriculture is as important as other sectors. However, of those learners who indicated an intention to pursue agriculture as a career, only 1 % specifically wished to become a farmer. The others rather wanted professional careers within the agricultural sector, such as veterinarians, agricultural economists, and so forth. Their interest in agriculture as a career related in large measure to a desire to live in a rural area and work with their hands; however this did not extend to actual farming. , Thesis (M Agric) -- Faculty of Science and Agriculture, 2016
- Full Text:
- Date Issued: 2016
An assessment of public support given to land reform commonage farmers by local and provincial government and their perfomance: A case study of Makana Local Municipality in Eastern Cape
- Authors: Gqweta, N V P
- Date: 2016
- Subjects: Land reform -- South Africa , Land use
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/23991 , vital:62238
- Description: Access to land is very important for previously disadvantage people from the countries where agriculture is one of the main sources for employment in order to improve their livelihoods. Worldwide, Land Reform arose mainly because of inequalities of resources. In South Africa the Land Reform started in as early as 1658 where blacks were not afforded equal opportunities as white people and therefore off farm land and properties. When South Africa’s first democratic government came into power in 1994, one of its goals was to redress the injustice of the past and give back land to the previously disadvantaged people through various land reform programmes. One of the components of the land reform programme was the provision of commonages lands to urban municipalities for use by the urban poor. The Department of Rural Development and Land Reform acquired commonages land for the municipalities for the purpose of agricultural production. The study focused on the Municipal Commonage Programme and this has been done by assessing the public support given to land reform commonage farmers by local and provincial government and their performance in Makana Local Municipality in Eastern Cape. The study showed that land reform commonage emerging farmers are confronted by numerous challenges such as poor infrastructure, access to markets, mentorship, credit, transport by beneficiaries, lack of support from government departments and lack of co-ordination between government departments. These and other challenges ultimately hamper beneficiaries from making effective use of land. The study was done on eight commonages in Makana Municipality. The data was analyzed using Statistical Package for the Social Science (SPSS) and Microsoft Excel. Data collection entailed questionnaire, interviews and focus group discussions. In view of the challenges for commonage farmers, this study provides recommendation for improving the commonage land reform redistribution projects. Current management attempts are not ensuring the efficient equitable and sustainable use of these commonages. Municipal Commonage should be better integrated into agrarian reform through leases and an efficient Commonage Farmers Support Programmes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2016
- Full Text:
- Date Issued: 2016
- Authors: Gqweta, N V P
- Date: 2016
- Subjects: Land reform -- South Africa , Land use
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/23991 , vital:62238
- Description: Access to land is very important for previously disadvantage people from the countries where agriculture is one of the main sources for employment in order to improve their livelihoods. Worldwide, Land Reform arose mainly because of inequalities of resources. In South Africa the Land Reform started in as early as 1658 where blacks were not afforded equal opportunities as white people and therefore off farm land and properties. When South Africa’s first democratic government came into power in 1994, one of its goals was to redress the injustice of the past and give back land to the previously disadvantaged people through various land reform programmes. One of the components of the land reform programme was the provision of commonages lands to urban municipalities for use by the urban poor. The Department of Rural Development and Land Reform acquired commonages land for the municipalities for the purpose of agricultural production. The study focused on the Municipal Commonage Programme and this has been done by assessing the public support given to land reform commonage farmers by local and provincial government and their performance in Makana Local Municipality in Eastern Cape. The study showed that land reform commonage emerging farmers are confronted by numerous challenges such as poor infrastructure, access to markets, mentorship, credit, transport by beneficiaries, lack of support from government departments and lack of co-ordination between government departments. These and other challenges ultimately hamper beneficiaries from making effective use of land. The study was done on eight commonages in Makana Municipality. The data was analyzed using Statistical Package for the Social Science (SPSS) and Microsoft Excel. Data collection entailed questionnaire, interviews and focus group discussions. In view of the challenges for commonage farmers, this study provides recommendation for improving the commonage land reform redistribution projects. Current management attempts are not ensuring the efficient equitable and sustainable use of these commonages. Municipal Commonage should be better integrated into agrarian reform through leases and an efficient Commonage Farmers Support Programmes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2016
- Full Text:
- Date Issued: 2016
An empirical investigation of the demand for money in South Africa within the inflation-targeting era
- Authors: Duah, Rachel
- Date: 2016
- Subjects: South Africa--Economic conditions http://id.loc.gov/authorities/subjects/sh85125465 , Inflation targeting--South Africa , Monetary policy--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19465 , vital:43127
- Description: The aim of the study is to empirically test the demand for money function in South Africa’s inflation-targeting era. This came from the fact that there have been a number of structural changes in the South African economy that have appeared to alter the relation between M3 and GDP and other macroeconomic variables. The study employed co-integration tests that showed one co-integrating equation which led to the application of the Vector-Error Correction Model (VECM) using the quarterly time series data covering the period from 2000-2015. The demand for money is investigated by estimating the real money balances as a function of Treasury Bills rate, income and total credit. Results showed that there is a negative relationship among Treasury Bills rate, income and real money balances. However, there is a positive relationship between real money balances and the total credit provided by the banking sector. The CUSUM and CUSUMQ tests are applied to examine the possibility of structural breaks in money demand functions, as well as parameter stability. The results of the study indicated that the estimated parameters for the short and long run dynamics of the real money demand function are stable. It was evident that Treasury bill rate, income and total credit can explain money balances and therefore can influence demand for money. The study recommends that the government ensures that there are economic activities such as employment creation which can then boost income levels so as to get a positive relationship between money balances and income. Through employment creation, there can be a reduction in borrowing. Treasury bill rates, being an effective monetary policy tool, can be used to direct monetary policy and also promote price stability. The study recommends that the South African Reserve Bank continue to improve the conditions in the financial sector. In this regard, the SARB and the government should strive to enact flexible policies that will boost financial credit and uplift business confidence. , Thesis (MCom)(Economics) -- University of Fort Hare, 2016
- Full Text:
- Date Issued: 2016
- Authors: Duah, Rachel
- Date: 2016
- Subjects: South Africa--Economic conditions http://id.loc.gov/authorities/subjects/sh85125465 , Inflation targeting--South Africa , Monetary policy--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19465 , vital:43127
- Description: The aim of the study is to empirically test the demand for money function in South Africa’s inflation-targeting era. This came from the fact that there have been a number of structural changes in the South African economy that have appeared to alter the relation between M3 and GDP and other macroeconomic variables. The study employed co-integration tests that showed one co-integrating equation which led to the application of the Vector-Error Correction Model (VECM) using the quarterly time series data covering the period from 2000-2015. The demand for money is investigated by estimating the real money balances as a function of Treasury Bills rate, income and total credit. Results showed that there is a negative relationship among Treasury Bills rate, income and real money balances. However, there is a positive relationship between real money balances and the total credit provided by the banking sector. The CUSUM and CUSUMQ tests are applied to examine the possibility of structural breaks in money demand functions, as well as parameter stability. The results of the study indicated that the estimated parameters for the short and long run dynamics of the real money demand function are stable. It was evident that Treasury bill rate, income and total credit can explain money balances and therefore can influence demand for money. The study recommends that the government ensures that there are economic activities such as employment creation which can then boost income levels so as to get a positive relationship between money balances and income. Through employment creation, there can be a reduction in borrowing. Treasury bill rates, being an effective monetary policy tool, can be used to direct monetary policy and also promote price stability. The study recommends that the South African Reserve Bank continue to improve the conditions in the financial sector. In this regard, the SARB and the government should strive to enact flexible policies that will boost financial credit and uplift business confidence. , Thesis (MCom)(Economics) -- University of Fort Hare, 2016
- Full Text:
- Date Issued: 2016
An unsung dialogue: music, society and the history of The Flames
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
Antibacterial effects of Alchornea cordifolia (Schumach. and Thonn.) Müll. Arg extracts and compounds on gastrointestinal, skin, respiratory and urinary tract pathogens
- Siwe-Noundou, Xavier, Krause, Rui W M, van Vuuren, Sandy, Tantoh Ndinteh, Derek, Olivier, Denise K
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, Denise K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, Denise K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
Behaviour and trophic ecology of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) associated with floating objects in the open ocean
- Forget, Fabien Rocky Gilbert
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
- Date Issued: 2016
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
- Date Issued: 2016
Can local use assist in controlling invasive alien species in tropical forests?: The case of Lantana camara in southern India
- Kannan, Ramesh, Shackleton, Charlie M, Krishnan, Smitha, Shaanker, Ramanan U
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Krishnan, Smitha , Shaanker, Ramanan U
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180423 , vital:43387 , xlink:href="https://doi.org/10.1016/j.foreco.2016.06.016"
- Description: Many invasive alien species (IAS) are used by local communities for a variety of subsistence and income generating purposes. This frequently poses a conflict of interest for their removal due to forest conservation and biodiversity concerns. However, if local use can simultaneously check or control specific IAS, the conflict can be avoided and both development and forest conservation perspectives accommodated in the short to medium term. We examine this for Lantana camara invasion in southern India through assessment of the demand for and impacts of harvesting on this globally problematic IAS. We interviewed local artisans regarding their knowledge and quantities of Lantana used, along with forest surveys to estimate Lantana densities and size classes in harvested and unharvested sites, and lastly we undertook controlled cutting in moist and dry deciduous forests in both the wet and dry seasons to examine rate of regrowth and mortality. Over the entire study area the abundance of Lantana far outweighed local demand, but at small scales around villages, density and size classes were significantly reduced through harvesting. The controlled cutting experiment showed marked seasonal differences, with the most severe cutting intensity resulting in significant mortality when Lantana plants were cut in the wet season, but with limited effect when cut in the dry season. We conclude that promoting local use of IAS may be a feasible approach in controlling them and thereby limiting their impacts in forests.
- Full Text:
- Date Issued: 2016
- Authors: Kannan, Ramesh , Shackleton, Charlie M , Krishnan, Smitha , Shaanker, Ramanan U
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180423 , vital:43387 , xlink:href="https://doi.org/10.1016/j.foreco.2016.06.016"
- Description: Many invasive alien species (IAS) are used by local communities for a variety of subsistence and income generating purposes. This frequently poses a conflict of interest for their removal due to forest conservation and biodiversity concerns. However, if local use can simultaneously check or control specific IAS, the conflict can be avoided and both development and forest conservation perspectives accommodated in the short to medium term. We examine this for Lantana camara invasion in southern India through assessment of the demand for and impacts of harvesting on this globally problematic IAS. We interviewed local artisans regarding their knowledge and quantities of Lantana used, along with forest surveys to estimate Lantana densities and size classes in harvested and unharvested sites, and lastly we undertook controlled cutting in moist and dry deciduous forests in both the wet and dry seasons to examine rate of regrowth and mortality. Over the entire study area the abundance of Lantana far outweighed local demand, but at small scales around villages, density and size classes were significantly reduced through harvesting. The controlled cutting experiment showed marked seasonal differences, with the most severe cutting intensity resulting in significant mortality when Lantana plants were cut in the wet season, but with limited effect when cut in the dry season. We conclude that promoting local use of IAS may be a feasible approach in controlling them and thereby limiting their impacts in forests.
- Full Text:
- Date Issued: 2016
Case Studies for UNECCC, UNESCO and CEE The COPART Climate Train
- Authors: McGarry, Dylan K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391120 , vital:68622 , xlink:href="https://eeasa.org.za/wp-content/uploads/2017/05/EEASA-Bullitin-2016_18-July-issue-42.pdf"
- Description: To create a listening and educational platform that used various disciplines to understand the impact of Climate Change across South Africa. The objective was to create a multigenre educational space for citizens of South Africa as a means to participate in Climate discussions as an alternative to the COP17 negotiations held in South Africa at the time.
- Full Text:
- Date Issued: 2016
- Authors: McGarry, Dylan K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391120 , vital:68622 , xlink:href="https://eeasa.org.za/wp-content/uploads/2017/05/EEASA-Bullitin-2016_18-July-issue-42.pdf"
- Description: To create a listening and educational platform that used various disciplines to understand the impact of Climate Change across South Africa. The objective was to create a multigenre educational space for citizens of South Africa as a means to participate in Climate discussions as an alternative to the COP17 negotiations held in South Africa at the time.
- Full Text:
- Date Issued: 2016
Characterization and Electrocatalytic Activity of Nanocomposites Consisting of Nanosized Cobalt Tetraaminophenoxy Phthalocyanine, Multi‐walled Carbon Nanotubes and Gold Nanoparticles
- Shumba, Munyaradzi, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188659 , vital:44773 , xlink:href="https://doi.org/10.1002/elan.201501058"
- Description: Glassy carbon electrodes were modified with composites containing cobalt tetraaminophenoxy phthalocyanine nanoparticles (CoTAPhPcNP), multi-walled carbon nanotubes (MWCNT) and gold nanorods (AuNRs). The modified electrodes were studied for their electrocatalytic behavior towards the reduction of hydrogen peroxide. Phthalocyanine nanoparticles significantly improved electron transfer kinetics as compared to phthalocyanines which are not in the nanoparticle form when alone or in the presence of multiwalled carbon nanotubes (MWCNTs). CoTAPhPcNP-MWCNT-GCE proved to be suitable for hydrogen peroxide detection with a catalytic rate constant of 3.45×103 M−1 s−1 and a detection limit of 1.61×10−7 M. Adsorption Gibbs free energy ΔGo was found to be −19.22 kJ mol−1 for CoTAPhPcNP-MWCNT-GCE.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188659 , vital:44773 , xlink:href="https://doi.org/10.1002/elan.201501058"
- Description: Glassy carbon electrodes were modified with composites containing cobalt tetraaminophenoxy phthalocyanine nanoparticles (CoTAPhPcNP), multi-walled carbon nanotubes (MWCNT) and gold nanorods (AuNRs). The modified electrodes were studied for their electrocatalytic behavior towards the reduction of hydrogen peroxide. Phthalocyanine nanoparticles significantly improved electron transfer kinetics as compared to phthalocyanines which are not in the nanoparticle form when alone or in the presence of multiwalled carbon nanotubes (MWCNTs). CoTAPhPcNP-MWCNT-GCE proved to be suitable for hydrogen peroxide detection with a catalytic rate constant of 3.45×103 M−1 s−1 and a detection limit of 1.61×10−7 M. Adsorption Gibbs free energy ΔGo was found to be −19.22 kJ mol−1 for CoTAPhPcNP-MWCNT-GCE.
- Full Text:
- Date Issued: 2016
Citizen Monitoring of the NWRS2. WRC report 2313
- Wilson, Jessica, Munnik, Victor, Burt, Jane C, Pereira, Taryn, Ngcozela, Thabang, Lusithi, Thabo, Lotz-Sisitka, Heila
- Authors: Wilson, Jessica , Munnik, Victor , Burt, Jane C , Pereira, Taryn , Ngcozela, Thabang , Lusithi, Thabo , Lotz-Sisitka, Heila
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432979 , vital:72920 , xlink:href="https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2313%20_final.pdf"
- Description: In 2014, the South African Water Caucus (SAWC), a network of non-governmental organisations (NGOs) and community-based organisations (CBOs) who are active in the water sector, embarked on a social learning and action research journey supported by the South African Water Research Commission (WRC) to deepen its monitoring of South Africa’s Second National Water Resources Strategy (NWRS2). They focused on three issues in three cases study areas.
- Full Text:
- Date Issued: 2016
- Authors: Wilson, Jessica , Munnik, Victor , Burt, Jane C , Pereira, Taryn , Ngcozela, Thabang , Lusithi, Thabo , Lotz-Sisitka, Heila
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432979 , vital:72920 , xlink:href="https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2313%20_final.pdf"
- Description: In 2014, the South African Water Caucus (SAWC), a network of non-governmental organisations (NGOs) and community-based organisations (CBOs) who are active in the water sector, embarked on a social learning and action research journey supported by the South African Water Research Commission (WRC) to deepen its monitoring of South Africa’s Second National Water Resources Strategy (NWRS2). They focused on three issues in three cases study areas.
- Full Text:
- Date Issued: 2016
Co-designing research on transgressive learning in times of climate change
- Lotz-Sisitka, Heila, Ali, Million B, Mphepho, Gibson, Chaves, Martha, Macintyre, Thomas, Pesanayi, Tichaona V, Wals, Arjen E, Mukute, Mutizwa, Kronlid, David O, Tran, Duc, Joon, Deepika, McGarry, Dylan K
- Authors: Lotz-Sisitka, Heila , Ali, Million B , Mphepho, Gibson , Chaves, Martha , Macintyre, Thomas , Pesanayi, Tichaona V , Wals, Arjen E , Mukute, Mutizwa , Kronlid, David O , Tran, Duc , Joon, Deepika , McGarry, Dylan K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182472 , vital:43833 , xlink:href="https://doi.org/10.1016/j.cosust.2016.04.004"
- Description: This paper reflects on the epistemological context for the co-design of a research programme on transformative, transgressive learning emerging at the nexus of climate change, water and food security, energy and social justice. It outlines a sequence of learning actions that we, as a group of collaborating partners in a Transformative Knowledge Network (TKN) undertook to co-design a research programme, firstly in situ in various case study contexts, and secondly together across case study contexts. Finally, it provides some reflections and learning points.
- Full Text:
- Date Issued: 2016
- Authors: Lotz-Sisitka, Heila , Ali, Million B , Mphepho, Gibson , Chaves, Martha , Macintyre, Thomas , Pesanayi, Tichaona V , Wals, Arjen E , Mukute, Mutizwa , Kronlid, David O , Tran, Duc , Joon, Deepika , McGarry, Dylan K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182472 , vital:43833 , xlink:href="https://doi.org/10.1016/j.cosust.2016.04.004"
- Description: This paper reflects on the epistemological context for the co-design of a research programme on transformative, transgressive learning emerging at the nexus of climate change, water and food security, energy and social justice. It outlines a sequence of learning actions that we, as a group of collaborating partners in a Transformative Knowledge Network (TKN) undertook to co-design a research programme, firstly in situ in various case study contexts, and secondly together across case study contexts. Finally, it provides some reflections and learning points.
- Full Text:
- Date Issued: 2016
Collaborative learning of water conservation practices: cultivation and expansion of a learning network around rainwater harvesting demonstration sites in the Eastern Cape, South Africa
- Pesanayi, Tichaona V, Weaver, Kim N
- Authors: Pesanayi, Tichaona V , Weaver, Kim N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392086 , vital:68720 , xlink:href="https://www.ajol.info/index.php/sajae/article/view/138570"
- Description: Learning together in mediated voluntary networks can mobilise skills and innovations that help to facilitate learning and uptake of rainwater harvesting and conservation practices. It boosts extension capacity while at the same time growing farmer capabilities, tapping on the distributed cognition. These practices help to heal wicked problems of drought and global change challenges affecting marginalised farmers in South Africa. South Africa has water, nutrition and food security challenges, especially the Eastern Cape Province where there is a relatively high level of poverty. These challenges place heavy pressure on the agricultural sector as it is the main user of the allocated water in the country. In this paper, the learning of and agency for rainwater harvesting and conservation practices are explored as responses to these challenges. Despite existing cultural histories of such practices among the amaXhosa people, information on these practices is not readily available to small-scale rural farmers who thus struggle for the want of knowing. This research forms part of a Water Research Commission project, Amanzi for Food, whose intention is to mediate collaborative and co-engaged learning among networked farmers, extension workers, researchers and agricultural educators through course-mediated use of Water Research Commission rainwater harvesting and conservation materials.
- Full Text:
- Date Issued: 2016
- Authors: Pesanayi, Tichaona V , Weaver, Kim N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392086 , vital:68720 , xlink:href="https://www.ajol.info/index.php/sajae/article/view/138570"
- Description: Learning together in mediated voluntary networks can mobilise skills and innovations that help to facilitate learning and uptake of rainwater harvesting and conservation practices. It boosts extension capacity while at the same time growing farmer capabilities, tapping on the distributed cognition. These practices help to heal wicked problems of drought and global change challenges affecting marginalised farmers in South Africa. South Africa has water, nutrition and food security challenges, especially the Eastern Cape Province where there is a relatively high level of poverty. These challenges place heavy pressure on the agricultural sector as it is the main user of the allocated water in the country. In this paper, the learning of and agency for rainwater harvesting and conservation practices are explored as responses to these challenges. Despite existing cultural histories of such practices among the amaXhosa people, information on these practices is not readily available to small-scale rural farmers who thus struggle for the want of knowing. This research forms part of a Water Research Commission project, Amanzi for Food, whose intention is to mediate collaborative and co-engaged learning among networked farmers, extension workers, researchers and agricultural educators through course-mediated use of Water Research Commission rainwater harvesting and conservation materials.
- Full Text:
- Date Issued: 2016