Invasive alien aquatic plant species management drives aquatic ecosystem community recovery: An exploration using stable isotope analysis
- Motitsoe, Samuel N, Hill, Jaclyn M, Coetzee, Julie A, Hill, Martin P
- Authors: Motitsoe, Samuel N , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423527 , vital:72069 , xlink:href="https://doi.org/10.1016/j.biocontrol.2022.104995"
- Description: The socio-economic and ecological impacts of invasive alien aquatic plant (IAAP) species have been well studied globally. However less is known about ecosystem recovery following the management of IAAP species. This study employed a before-after study design to investigate ecological recovery following the management of Salvinia molesta D.S. Mitchell, at four field sites in South Africa. We hypothesized that the presence of S. molesta would have a negative impact on the ecosystem food web structure, and that following S. molesta control, the systems would show positive ecosystem recovery. Aquatic macroinvertebrate and macrophyte samples collected before and after mechanical or biological control of S. molesta, were analysed for δ13C and δ15N stable isotopes. Salvinia molesta infestations negatively impacted the food web structure, indicated by reduced food chain length, trophic diversity and basal resources. This represented an altered aquatic food web structure, that in some cases, led to the collapse of the aquatic community. In contrast, after either mechanical or biological control, there were increases in food chain length, trophic diversity and abundance of energy resources accessed by consumers, indicating improved food web structure. Although the study showed positive ecosystem recovery following control, we noted that each control method followed a different recovery trajectory. We conclude that S. molesta invasions reduce aquatic biodiversity and alter ecosystem trophic dynamics and related ecosystem processes, necessitating control.
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- Authors: Motitsoe, Samuel N , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423527 , vital:72069 , xlink:href="https://doi.org/10.1016/j.biocontrol.2022.104995"
- Description: The socio-economic and ecological impacts of invasive alien aquatic plant (IAAP) species have been well studied globally. However less is known about ecosystem recovery following the management of IAAP species. This study employed a before-after study design to investigate ecological recovery following the management of Salvinia molesta D.S. Mitchell, at four field sites in South Africa. We hypothesized that the presence of S. molesta would have a negative impact on the ecosystem food web structure, and that following S. molesta control, the systems would show positive ecosystem recovery. Aquatic macroinvertebrate and macrophyte samples collected before and after mechanical or biological control of S. molesta, were analysed for δ13C and δ15N stable isotopes. Salvinia molesta infestations negatively impacted the food web structure, indicated by reduced food chain length, trophic diversity and basal resources. This represented an altered aquatic food web structure, that in some cases, led to the collapse of the aquatic community. In contrast, after either mechanical or biological control, there were increases in food chain length, trophic diversity and abundance of energy resources accessed by consumers, indicating improved food web structure. Although the study showed positive ecosystem recovery following control, we noted that each control method followed a different recovery trajectory. We conclude that S. molesta invasions reduce aquatic biodiversity and alter ecosystem trophic dynamics and related ecosystem processes, necessitating control.
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Biological control of Salvinia molesta (DS Mitchell) drives aquatic ecosystem recovery
- Motitsoe, Samuel N, Coetzee, Julie A, Hill, Jaclyn M, Hill, Martin P
- Authors: Motitsoe, Samuel N , Coetzee, Julie A , Hill, Jaclyn M , Hill, Martin P
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444515 , vital:74247 , https://doi.org/10.3390/d12050204
- Description: Salvinia molesta D.S. Mitchell (Salviniaceae) is a damaging free-floating invasive alien macrophyte native to South America. The biological control programme against S. molesta by the weevil Cyrtobagous salviniae Calder and Sands (Erirhinidae) has been successful in controlling S. molesta infestations in the introduced range, however, there is some debate as to how biological control success is measured. This study measured the response of epilithic algae and aquatic macroinvertebrate communities in a S. molesta-dominated state and subsequently where the weed had been cleared by biological control, as a proxy for ecosystem recovery in a before–after control–impact mesocosm experiment.
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- Authors: Motitsoe, Samuel N , Coetzee, Julie A , Hill, Jaclyn M , Hill, Martin P
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444515 , vital:74247 , https://doi.org/10.3390/d12050204
- Description: Salvinia molesta D.S. Mitchell (Salviniaceae) is a damaging free-floating invasive alien macrophyte native to South America. The biological control programme against S. molesta by the weevil Cyrtobagous salviniae Calder and Sands (Erirhinidae) has been successful in controlling S. molesta infestations in the introduced range, however, there is some debate as to how biological control success is measured. This study measured the response of epilithic algae and aquatic macroinvertebrate communities in a S. molesta-dominated state and subsequently where the weed had been cleared by biological control, as a proxy for ecosystem recovery in a before–after control–impact mesocosm experiment.
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Synergies between research organisations and the wider community in enhancing weed biological control in South Africa
- Martin, Grant D, Hill, Martin P, Coetzee, Julie A, Weaver, Kim N, Hill, Jaclyn M
- Authors: Martin, Grant D , Hill, Martin P , Coetzee, Julie A , Weaver, Kim N , Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68452 , vital:29258 , https://doi.org/10.1007/s10526-017-9846-4
- Description: Biological control offers a cost effective and ecologically sustainable tool for the management of invasive alien plants. Its implementation, however, has historically been slow and poorly co-ordinated. In South Africa, as in many other countries, most aspects of biological control programmes were done by researchers, but from 1995 onwards, with the advent of the Working for Water Programme, a more inclusive approach to biological control has been adopted. In this paper, we report on the development of community-based biological control implementation programmes in South Africa, after 1995, and highlight a number of initiatives, including employing persons with disabilities at mass-rearing facilities and in particular, we outline a suite of educational and outreach programmes for the general public and for schools, which have increased capacity, education and employment in the field of weed biological control.
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- Authors: Martin, Grant D , Hill, Martin P , Coetzee, Julie A , Weaver, Kim N , Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68452 , vital:29258 , https://doi.org/10.1007/s10526-017-9846-4
- Description: Biological control offers a cost effective and ecologically sustainable tool for the management of invasive alien plants. Its implementation, however, has historically been slow and poorly co-ordinated. In South Africa, as in many other countries, most aspects of biological control programmes were done by researchers, but from 1995 onwards, with the advent of the Working for Water Programme, a more inclusive approach to biological control has been adopted. In this paper, we report on the development of community-based biological control implementation programmes in South Africa, after 1995, and highlight a number of initiatives, including employing persons with disabilities at mass-rearing facilities and in particular, we outline a suite of educational and outreach programmes for the general public and for schools, which have increased capacity, education and employment in the field of weed biological control.
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The contributions of biological control to reduced plant size and biomass of water hyacinth populations
- Jones, Roy W, Hill, Jaclyn M, Coetzee, Julie A, Hill, Martin P
- Authors: Jones, Roy W , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68803 , vital:29326 , https://0-doi.org.wam.seals.ac.za/10.1007/s10750-017-3413-y
- Description: Water hyacinth is invasive in many countries, where it reduces aquatic biodiversity and limits water resource utilisation. Biological control of water hyacinth has been successful in South Africa, but has suffered from a lack of empirical data to prove causation. Insect exclusion trials were conducted to quantify the contribution of Neochetina eichhorniae and N. bruchi to the integrated control of water hyacinth on the Nseleni River, South Africa. Insecticide was not expected to induce phytotoxicity, but would prevent weevil damage in water hyacinth plants; and weevil herbivory was predicted to reduce plant petiole length, and above/below surface biomass. Results showed that insecticide had no phytotoxic effects and excluded weevils for 3 weeks, providing a baseline for field applications. Biological control on the Nseleni River directly affected water hyacinth biomass and petiole length, but did not affect plant cover. Plants subject to weevil herbivory demonstrated reductions in above and below surface biomass and had shorter petioles compared to insect-free plants. Dead biomass was also higher in biological control treatments. Biological control strongly affects plant size, biomass and vigour; however, further integrated control is required to facilitate reduction in mat cover, which is the goalpost for successful control of floating aquatic plants.
- Full Text: false
- Authors: Jones, Roy W , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68803 , vital:29326 , https://0-doi.org.wam.seals.ac.za/10.1007/s10750-017-3413-y
- Description: Water hyacinth is invasive in many countries, where it reduces aquatic biodiversity and limits water resource utilisation. Biological control of water hyacinth has been successful in South Africa, but has suffered from a lack of empirical data to prove causation. Insect exclusion trials were conducted to quantify the contribution of Neochetina eichhorniae and N. bruchi to the integrated control of water hyacinth on the Nseleni River, South Africa. Insecticide was not expected to induce phytotoxicity, but would prevent weevil damage in water hyacinth plants; and weevil herbivory was predicted to reduce plant petiole length, and above/below surface biomass. Results showed that insecticide had no phytotoxic effects and excluded weevils for 3 weeks, providing a baseline for field applications. Biological control on the Nseleni River directly affected water hyacinth biomass and petiole length, but did not affect plant cover. Plants subject to weevil herbivory demonstrated reductions in above and below surface biomass and had shorter petioles compared to insect-free plants. Dead biomass was also higher in biological control treatments. Biological control strongly affects plant size, biomass and vigour; however, further integrated control is required to facilitate reduction in mat cover, which is the goalpost for successful control of floating aquatic plants.
- Full Text: false
Community entomology: insects, science and society
- Weaver, Kim N, Hill, Jaclyn M, Martin, Grant D, Paterson, Iain D, Coetzee, Julie A, Hill, Martin P
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
- Full Text:
- Authors: Weaver, Kim N , Hill, Jaclyn M , Martin, Grant D , Paterson, Iain D , Coetzee, Julie A , Hill, Martin P
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123343 , vital:35429 , https://hdl.handle.net/10520/EJC-c859bebd5
- Description: Educative outreach programmes have been found to be effective ways in which to raise awareness around basic scientific concepts. The Biological Control Research Group (BCRG) in the Department of Zoology and Entomology at Rhodes University, South Africa, is involved in community engaged initiatives that aim to be interactive and informative around entomology, and more specifically, the use of biological control against invasive alien plants. As a higher education institution, Rhodes University has a civic responsibility to engage with local communities and work with them around local challenges. Three groups of activities undertaken by the BCRG in partnership with local schools and other community partners are described and assessed in this paper as a way of assessing them and exploring future research areas around the aims and outcomes of these programmes.
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The abundance of an invasive freshwater snail Tarebia granifera (Lamarck, 1822) in the Nseleni River, South Africa
- Jones, Roy W, Hill, Jaclyn M, Coetzee, Julie A, Hill, Martin P, Avery, T S, Weyl, Olaf L F
- Authors: Jones, Roy W , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P , Avery, T S , Weyl, Olaf L F
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69077 , vital:29382 , https://doi.org/10.2989/16085914.2017.1298984
- Description: The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region.
- Full Text: false
- Authors: Jones, Roy W , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P , Avery, T S , Weyl, Olaf L F
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69077 , vital:29382 , https://doi.org/10.2989/16085914.2017.1298984
- Description: The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region.
- Full Text: false
A stable isotope approach for the early detection and identification of N loading in aquatic ecosystems
- Hill, Jaclyn M, Kaehler, Sven, Hill, Martin P, Coetzee, Julie A
- Authors: Hill, Jaclyn M , Kaehler, Sven , Hill, Martin P , Coetzee, Julie A
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444491 , vital:74245 , https://www.wrc.org.za/wp-content/uploads/mdocs/KV 280.pdf
- Description: Global increases in urbanization and anthropogenic activity within wa-tersheds and catchment areas have resulted in excessive nitrogen loads in aquatic ecosystems. South Africa is deeply dependent on nat-ural resources for its economic health and as a consequence is particu-larly vulnerable to the degradation of its natural capital. Increased nitro-gen loading can result in widespread aquatic ecosystem degradation including: harmful algal blooms, increased turbidity, hypoxia, loss of aquatic vegetation and habitat and fish kills, it is also one of the mecha-nisms driving aquatic weed invasions. Understanding the fate and pro-cessing of anthropogenic nutrients in natural systems is therefore criti-cal for both preserving the well-being and biotic heritage for future gen-erations as well as providing a tremendous opportunity to improve the management driven by science. The objectives of this study were to evaluate the feasibility of mapping anthropogenic pollution through sta-ble isotopes signatures of aquatic plants, to investigate the potential for identifying different pollution sources, concentrations and distributions in a freshwater environment and to determine the utility of these tech-niques in indentifying early eutrophication.
- Full Text:
- Authors: Hill, Jaclyn M , Kaehler, Sven , Hill, Martin P , Coetzee, Julie A
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444491 , vital:74245 , https://www.wrc.org.za/wp-content/uploads/mdocs/KV 280.pdf
- Description: Global increases in urbanization and anthropogenic activity within wa-tersheds and catchment areas have resulted in excessive nitrogen loads in aquatic ecosystems. South Africa is deeply dependent on nat-ural resources for its economic health and as a consequence is particu-larly vulnerable to the degradation of its natural capital. Increased nitro-gen loading can result in widespread aquatic ecosystem degradation including: harmful algal blooms, increased turbidity, hypoxia, loss of aquatic vegetation and habitat and fish kills, it is also one of the mecha-nisms driving aquatic weed invasions. Understanding the fate and pro-cessing of anthropogenic nutrients in natural systems is therefore criti-cal for both preserving the well-being and biotic heritage for future gen-erations as well as providing a tremendous opportunity to improve the management driven by science. The objectives of this study were to evaluate the feasibility of mapping anthropogenic pollution through sta-ble isotopes signatures of aquatic plants, to investigate the potential for identifying different pollution sources, concentrations and distributions in a freshwater environment and to determine the utility of these tech-niques in indentifying early eutrophication.
- Full Text:
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