Could enemy release explain invasion success of Sagittaria platyphylla in Australia and South Africa?.
- Kwong, Raelene M, Sagliocco, Jean Louis, Harms, Nathan E, Butler, Kym L, Martin, Grant D, Green, Peter T
- Authors: Kwong, Raelene M , Sagliocco, Jean Louis , Harms, Nathan E , Butler, Kym L , Martin, Grant D , Green, Peter T
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76881 , vital:30633 , https://doi.org/10.1016/j.aquabot.2018.11.011
- Description: Sagittaria platyphylla (delta arrowhead) is an emergent aquatic macrophyte native to southeastern United States of America that has been introduced into Australia and South Africa as an ornamental pond and aquarium plant. Compared to plants in the native range, S. platyphylla in the introduced range have greater reproductive capacity and form extensive infestations that dominate shallow waterbodies. One explanation for the invasive success of S. platyphylla in introduced countries is that plants are devoid of biotic pressures that would regulate population abundance in their native range (the enemy release hypothesis). We previously reported on field surveys that documented the number of pathogens and insect herbivores associated with S. platyphylla in native and introduced ranges. Here, we quantify the damage caused by these natural enemies to S. platyphylla in the two ranges. As predicted, damage to plants caused by pathogens and insect herbivores was much greater in the native than the introduced range at both the plant and population level. In introduced regions herbivory was low (less than 10%) in every plant part, while in North America insect damage to fruiting heads was 46% (of fruiting heads attacked), damage to leaves was between 33 to 57%, and internal herbivore damage to petioles and the inflorescence scapes was 56% and 43% respectively. Pathogen damage to leaves was between 39 to 57% of leaves per plant affected, compared to 9% in Australia and 8% in South Africa. This lack of biotic resistance from herbivores and disease may have facilitated S. platyphylla invasion in Australia and South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Kwong, Raelene M , Sagliocco, Jean Louis , Harms, Nathan E , Butler, Kym L , Martin, Grant D , Green, Peter T
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76881 , vital:30633 , https://doi.org/10.1016/j.aquabot.2018.11.011
- Description: Sagittaria platyphylla (delta arrowhead) is an emergent aquatic macrophyte native to southeastern United States of America that has been introduced into Australia and South Africa as an ornamental pond and aquarium plant. Compared to plants in the native range, S. platyphylla in the introduced range have greater reproductive capacity and form extensive infestations that dominate shallow waterbodies. One explanation for the invasive success of S. platyphylla in introduced countries is that plants are devoid of biotic pressures that would regulate population abundance in their native range (the enemy release hypothesis). We previously reported on field surveys that documented the number of pathogens and insect herbivores associated with S. platyphylla in native and introduced ranges. Here, we quantify the damage caused by these natural enemies to S. platyphylla in the two ranges. As predicted, damage to plants caused by pathogens and insect herbivores was much greater in the native than the introduced range at both the plant and population level. In introduced regions herbivory was low (less than 10%) in every plant part, while in North America insect damage to fruiting heads was 46% (of fruiting heads attacked), damage to leaves was between 33 to 57%, and internal herbivore damage to petioles and the inflorescence scapes was 56% and 43% respectively. Pathogen damage to leaves was between 39 to 57% of leaves per plant affected, compared to 9% in Australia and 8% in South Africa. This lack of biotic resistance from herbivores and disease may have facilitated S. platyphylla invasion in Australia and South Africa.
- Full Text:
- Date Issued: 2019
In vitro and in vivo toxicity assessment of biologically synthesized silver nanoparticles from Elaeodendron croceum:
- Odeyemi, S W, de la Mare, Jo-Anne, Edkins, Adrienne L, Afolayan, A J
- Authors: Odeyemi, S W , de la Mare, Jo-Anne , Edkins, Adrienne L , Afolayan, A J
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163488 , vital:41042 , DOI: 10.1515/jcim-2018-0184
- Description: The cytotoxic properties of nanoparticles have attracted a great deal of attention in the field of nanoscience and nanotechnology due to their small size and ability to penetrate cellular membranes.
- Full Text:
- Date Issued: 2019
- Authors: Odeyemi, S W , de la Mare, Jo-Anne , Edkins, Adrienne L , Afolayan, A J
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163488 , vital:41042 , DOI: 10.1515/jcim-2018-0184
- Description: The cytotoxic properties of nanoparticles have attracted a great deal of attention in the field of nanoscience and nanotechnology due to their small size and ability to penetrate cellular membranes.
- Full Text:
- Date Issued: 2019
Movement and predation: a catch-and-release study on the acoustic tracking of bonefish in the Indian Ocean
- Moxham, Emily Jeanne, Cowley, Paul D, Bennett, Rhett H, von Brandis, Rainer G
- Authors: Moxham, Emily Jeanne , Cowley, Paul D , Bennett, Rhett H , von Brandis, Rainer G
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103946 , vital:32325 , https://doi.org/10.1007/s10641-019-00850-1
- Description: Tourism generated through bonefish (Albula spp.) fishing contributes to the economies of many isolated tropical islands and atolls. However, little research has been conducted on bonefish in the Indian Ocean. This study aimed to contribute to the understanding of bonefish ecology in the Indian Ocean by quantifying the spatial and temporal movements of Albula glossodonta at a near-pristine and predator-rich atoll in the Seychelles; however, to achieve this, an analysis to identify the occurrence of possible post-release predation bias was first necessary. An acoustic telemetry study was initiated at the remote St. Joseph Atoll, within an array of 88 automated data-logging acoustic receivers. Thirty bonefish were surgically implanted with Vemco V13 acoustic transmitters and tracked for one year. Only 10% of the tagged bonefish were detected for longer than two weeks. A comparison of the final 100 h of movement data from fish detected for less than two weeks to the movement data of the fish detected for longer periods revealed distinct differences in area use and significant differences in the average daily distance moved, speed of movement and frequency of detections. This suggested that mortality in the form of post-release predation was at least 43% of tagged fish. The three surviving bonefish were tracked for 210 to 367 days. These individuals remained in the atoll and showed high use of the marginal habitats between the shallow sand flats and the lagoon. A generalised linear mixed model identified that water temperature, diel cycle and tide were significant predictors of bonefish presence in the lagoon. The high post-release mortality highlights that catch-and-release is likely not as benign as previously believed and management and policy should be adjusted accordingly.
- Full Text:
- Date Issued: 2019
- Authors: Moxham, Emily Jeanne , Cowley, Paul D , Bennett, Rhett H , von Brandis, Rainer G
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/103946 , vital:32325 , https://doi.org/10.1007/s10641-019-00850-1
- Description: Tourism generated through bonefish (Albula spp.) fishing contributes to the economies of many isolated tropical islands and atolls. However, little research has been conducted on bonefish in the Indian Ocean. This study aimed to contribute to the understanding of bonefish ecology in the Indian Ocean by quantifying the spatial and temporal movements of Albula glossodonta at a near-pristine and predator-rich atoll in the Seychelles; however, to achieve this, an analysis to identify the occurrence of possible post-release predation bias was first necessary. An acoustic telemetry study was initiated at the remote St. Joseph Atoll, within an array of 88 automated data-logging acoustic receivers. Thirty bonefish were surgically implanted with Vemco V13 acoustic transmitters and tracked for one year. Only 10% of the tagged bonefish were detected for longer than two weeks. A comparison of the final 100 h of movement data from fish detected for less than two weeks to the movement data of the fish detected for longer periods revealed distinct differences in area use and significant differences in the average daily distance moved, speed of movement and frequency of detections. This suggested that mortality in the form of post-release predation was at least 43% of tagged fish. The three surviving bonefish were tracked for 210 to 367 days. These individuals remained in the atoll and showed high use of the marginal habitats between the shallow sand flats and the lagoon. A generalised linear mixed model identified that water temperature, diel cycle and tide were significant predictors of bonefish presence in the lagoon. The high post-release mortality highlights that catch-and-release is likely not as benign as previously believed and management and policy should be adjusted accordingly.
- Full Text:
- Date Issued: 2019
Plaxenone A and B: Cytotoxic halogenated monoterpenes from the South African red seaweed Plocamium maxillosum
- Knott, Michael G, de la Mare, Jo-Anne, Edkins, Adrienne L, Zhang, Angel, Stillman, Martin J, Bolton, John J, Antunes, Edith M, Beukes, Denzil R
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
Prime time geographies: dancehall performance, visual communication and the philosophy of ‘Boundarylessness'
- Authors: Stanley Niaah, Sonjah
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145930 , vital:38479 , https://0-doi.org.wam.seals.ac.za/10.1080/00086495.2019.1565218
- Description: What is Dancehall, and how does it employ visual technologies? Dancehall is not just a musical genre. It is Jamaica’s premier popular street theatre, a celebration of the entire spectrum of life from birth to death, expressed at events that combine dance and music, where consenting adults leave their troubles behind just for a moment to revel in the deep and old rhythmic structures that transport them into scape beyond the urban, beyond the inner city, into spaces of fulfilment.
- Full Text:
- Date Issued: 2019
- Authors: Stanley Niaah, Sonjah
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145930 , vital:38479 , https://0-doi.org.wam.seals.ac.za/10.1080/00086495.2019.1565218
- Description: What is Dancehall, and how does it employ visual technologies? Dancehall is not just a musical genre. It is Jamaica’s premier popular street theatre, a celebration of the entire spectrum of life from birth to death, expressed at events that combine dance and music, where consenting adults leave their troubles behind just for a moment to revel in the deep and old rhythmic structures that transport them into scape beyond the urban, beyond the inner city, into spaces of fulfilment.
- Full Text:
- Date Issued: 2019
Semi-synthesis and evaluation of sargahydroquinoic acid derivatives as potential antimalarial agents:
- Munedzimwe, Tatenda C, van Zyl, Rovyn L, Heslop, Donovan C, Edkins, Adrienne L, Beukes, Denzil R
- Authors: Munedzimwe, Tatenda C , van Zyl, Rovyn L , Heslop, Donovan C , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163456 , vital:41040 , DOI: 10.3390/medicines6020047
- Description: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been shown to exhibit antiplasmodial activity against a chloroquinone sensitive strain of Plasmodium falciparum (D10). In this study we explored the antiplasmodial activity of several semi-synthetic analogs of sargahydroquinoic acid.
- Full Text:
- Date Issued: 2019
- Authors: Munedzimwe, Tatenda C , van Zyl, Rovyn L , Heslop, Donovan C , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163456 , vital:41040 , DOI: 10.3390/medicines6020047
- Description: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been shown to exhibit antiplasmodial activity against a chloroquinone sensitive strain of Plasmodium falciparum (D10). In this study we explored the antiplasmodial activity of several semi-synthetic analogs of sargahydroquinoic acid.
- Full Text:
- Date Issued: 2019
The relation between galaxy density and radio jet power for 1.4 GHz VLA selected AGNs in Stripe 82
- Kolwa, S, Jarvis, M J, McAlpine, Kim, Heywood, Ian
- Authors: Kolwa, S , Jarvis, M J , McAlpine, Kim , Heywood, Ian
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/131444 , vital:36572 , https://doi.org/10.1093/mnras/sty3019
- Description: Using a Karl G. Jansky Very Large Array (VLA) L-band (1-2 GHz) survey covering ∼100 deg2 of the Stripe 82 field, we have obtained a catalogue of 2716 radio AGNs. For these AGNs, we investigate the impact of galaxy density on 1.4 GHz radio luminosity (L1.4). We determine their close environment densities using the surface density parameter, ΣN, for N = 2 and N = 5, which we bin by redshift to obtain a pseudo-3D galaxy density measure. Matching the radio AGNs to sources without radio detections in terms of redshift, K-band magnitude and (g − K) colour index, we obtain samples of control galaxies and determine whether radio AGN environments differ from this general population.
- Full Text:
- Date Issued: 2018
- Authors: Kolwa, S , Jarvis, M J , McAlpine, Kim , Heywood, Ian
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/131444 , vital:36572 , https://doi.org/10.1093/mnras/sty3019
- Description: Using a Karl G. Jansky Very Large Array (VLA) L-band (1-2 GHz) survey covering ∼100 deg2 of the Stripe 82 field, we have obtained a catalogue of 2716 radio AGNs. For these AGNs, we investigate the impact of galaxy density on 1.4 GHz radio luminosity (L1.4). We determine their close environment densities using the surface density parameter, ΣN, for N = 2 and N = 5, which we bin by redshift to obtain a pseudo-3D galaxy density measure. Matching the radio AGNs to sources without radio detections in terms of redshift, K-band magnitude and (g − K) colour index, we obtain samples of control galaxies and determine whether radio AGN environments differ from this general population.
- Full Text:
- Date Issued: 2018
- «
- ‹
- 1
- ›
- »