A review of the biological control programmes on Eichhornia crassipes (C. mart.) solms (Pontederiaceae), Salvinia molesta DS Mitch.(Salviniaceae), Pistia stratiotes L.(Araceae), Myriophyllum aquaticum (vell.) verdc.(Haloragaceae) and Azolla filiculoides Lam.(Azollaceae) in South Africa
- Coetzee, Julie A, Hill, Martin P, Byrne, Marcus J
- Authors: Coetzee, Julie A , Hill, Martin P , Byrne, Marcus J
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451285 , vital:75036 , https://hdl.handle.net/10520/EJC32900
- Description: Biological control against water hyacinth, Eichhornia crassipes (C. Mart.) Solms (Pontederiaceae), salvinia, Salvinia molesta D.S. Mitch. (Salviniaceae), water lettuce, Pistia stratiotes L. (Araceae), parrot's feather, Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae), and red water fern, Azolla filiculoides Lam. (Azollaceae) has been ongoing in South Africa since the release of the first biological control agent on water hyacinth in 1974. This review provides an account of progress for the period from 1999. Post-release evaluations over the last three years have shown that, with the exception of water hyacinth, all of these problematic aquatic plants have been suppressed effectively using classical biological control. In eutrophic water bodies at high elevations that experience cold winters, an integrated approach, that includes herbicide application and augmentive biological control, is required against water hyacinth. The grasshopper Cornops aquaticum (Brüner) (Orthoptera: Acrididae: Leptysminae) has recently been released as a new agent for water hyacinth, and Megamelus scutellaris Berg (Hemiptera: Delphacidae) and Taosa longula Remes Lenicov (Hemiptera: Dictyopharidae) are being considered for release on water hyacinth. The longterm management of alien aquatic plants in South Africa relies on the prevention of new introductions of aquatic plant species that could replace those that have been controlled, and, more importantly, on a reduction in nutrient levels in South Africa's aquatic ecosystems.
- Full Text:
- Date Issued: 2011
- Authors: Coetzee, Julie A , Hill, Martin P , Byrne, Marcus J
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451285 , vital:75036 , https://hdl.handle.net/10520/EJC32900
- Description: Biological control against water hyacinth, Eichhornia crassipes (C. Mart.) Solms (Pontederiaceae), salvinia, Salvinia molesta D.S. Mitch. (Salviniaceae), water lettuce, Pistia stratiotes L. (Araceae), parrot's feather, Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae), and red water fern, Azolla filiculoides Lam. (Azollaceae) has been ongoing in South Africa since the release of the first biological control agent on water hyacinth in 1974. This review provides an account of progress for the period from 1999. Post-release evaluations over the last three years have shown that, with the exception of water hyacinth, all of these problematic aquatic plants have been suppressed effectively using classical biological control. In eutrophic water bodies at high elevations that experience cold winters, an integrated approach, that includes herbicide application and augmentive biological control, is required against water hyacinth. The grasshopper Cornops aquaticum (Brüner) (Orthoptera: Acrididae: Leptysminae) has recently been released as a new agent for water hyacinth, and Megamelus scutellaris Berg (Hemiptera: Delphacidae) and Taosa longula Remes Lenicov (Hemiptera: Dictyopharidae) are being considered for release on water hyacinth. The longterm management of alien aquatic plants in South Africa relies on the prevention of new introductions of aquatic plant species that could replace those that have been controlled, and, more importantly, on a reduction in nutrient levels in South Africa's aquatic ecosystems.
- Full Text:
- Date Issued: 2011
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:
- Date Issued: 2011
- 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:
- Date Issued: 2011
Pet stores, aquarists and the internet trade as modes of introduction and spread of invasive macrophytes in South Africa
- Martin, Grant D, Coetzee, Julie A
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6843 , http://hdl.handle.net/10962/d1011045
- Description: Submerged aquatic invasive plant species are increasingly being recognised as a major threat to South African water ways. Pet stores, aquarists and the internet-mediated trade were investigated as pathways for submerged invasive macrophyte introductions into South Africa. Online and manually distributed surveys were used to determine the extent of movement of invasive as well as indigenous submerged plant species in South Africa. Sixty-four stores and twenty-three aquarists were surveyed. Four areas of risk were identified in this study. Firstly, and most importantly, a variety of invasive and/or prohibited plants are sold by pet stores. Secondly, there is a lack of knowledge regarding identification as well as regulation of submerged species, which may then result in the unintentional trade of potentially invasive species. It seems that, in many cases, the pet stores are ignorant or misinformed of the potential dangers, rather than intentionally attempting to breach the legislation. Thirdly, aquarists own, trade and move plants in and around the country, which makes it very difficult to monitor which species are being moved around South Africa and to what extent. Finally, the internet is a pathway of potential concern, but it is difficult to quantify its contribution to the trade of invasive species in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6843 , http://hdl.handle.net/10962/d1011045
- Description: Submerged aquatic invasive plant species are increasingly being recognised as a major threat to South African water ways. Pet stores, aquarists and the internet-mediated trade were investigated as pathways for submerged invasive macrophyte introductions into South Africa. Online and manually distributed surveys were used to determine the extent of movement of invasive as well as indigenous submerged plant species in South Africa. Sixty-four stores and twenty-three aquarists were surveyed. Four areas of risk were identified in this study. Firstly, and most importantly, a variety of invasive and/or prohibited plants are sold by pet stores. Secondly, there is a lack of knowledge regarding identification as well as regulation of submerged species, which may then result in the unintentional trade of potentially invasive species. It seems that, in many cases, the pet stores are ignorant or misinformed of the potential dangers, rather than intentionally attempting to breach the legislation. Thirdly, aquarists own, trade and move plants in and around the country, which makes it very difficult to monitor which species are being moved around South Africa and to what extent. Finally, the internet is a pathway of potential concern, but it is difficult to quantify its contribution to the trade of invasive species in South Africa.
- Full Text:
- Date Issued: 2011
Prospects for the biological control of submerged macrophytes in South Africa
- Coetzee, Julie A, Bownes, Angela, Martin, Grant D
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452295 , vital:75118 , https://hdl.handle.net/10520/EJC32899
- Description: Historically, biological control efforts against aquatic plants in South Africa have focused on floating species, and as a result, there has been a dearth of research into the invasion and control of submerged macrophytes. With numerous submerged invasive species already established in South Africa, thriving horticultural and aquarium industries, nutrient-rich water systems, and a limited knowledge of the drivers of invasions of submerged macrophytes, South Africa is highly vulnerable to a second phase of aquatic plant problems. Experience gained in the U.S.A. on biological control against submerged weeds, such as hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae) and spiked / Eurasian watermilfoil, Myriophyllum spicatum L. (Haloragaceae), have provided South African researchers with the necessary foundation to initiate programmes against these weeds. Research in South Africa is currently focused on pre-release studies on the biological control of H. verticillata, using an undescribed fly, Hydrellia sp. (Diptera: Ephydridae) and a weevil, Bagous hydrillae O'Brien (Coleoptera: Curculionidae); and on M. spicatum using a North American weevil, Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae). Feasibility studies into biological control of some incipient submerged weeds are also being conducted, including Brazilian water weed, Egeria densa Planch. (Hydrocharitaceae), Canadian water weed, Elodea canadensis Mitch. (Hydrocharitaceae) and cabomba, Cabomba caroliniana A. Gray (Cabombaceae). Progress with, and potential constraints that may limit these programmes, are discussed.
- Full Text:
- Date Issued: 2011
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452295 , vital:75118 , https://hdl.handle.net/10520/EJC32899
- Description: Historically, biological control efforts against aquatic plants in South Africa have focused on floating species, and as a result, there has been a dearth of research into the invasion and control of submerged macrophytes. With numerous submerged invasive species already established in South Africa, thriving horticultural and aquarium industries, nutrient-rich water systems, and a limited knowledge of the drivers of invasions of submerged macrophytes, South Africa is highly vulnerable to a second phase of aquatic plant problems. Experience gained in the U.S.A. on biological control against submerged weeds, such as hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae) and spiked / Eurasian watermilfoil, Myriophyllum spicatum L. (Haloragaceae), have provided South African researchers with the necessary foundation to initiate programmes against these weeds. Research in South Africa is currently focused on pre-release studies on the biological control of H. verticillata, using an undescribed fly, Hydrellia sp. (Diptera: Ephydridae) and a weevil, Bagous hydrillae O'Brien (Coleoptera: Curculionidae); and on M. spicatum using a North American weevil, Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae). Feasibility studies into biological control of some incipient submerged weeds are also being conducted, including Brazilian water weed, Egeria densa Planch. (Hydrocharitaceae), Canadian water weed, Elodea canadensis Mitch. (Hydrocharitaceae) and cabomba, Cabomba caroliniana A. Gray (Cabombaceae). Progress with, and potential constraints that may limit these programmes, are discussed.
- Full Text:
- Date Issued: 2011
The role of eutrophication in the biological control of water hyacinth, Eichhornia crassipes, in South Africa
- Coetzee, Julie A, Hill, Martin P
- Authors: Coetzee, Julie A , Hill, Martin P
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69263 , vital:29474 , https://doi.org/10.1007/s10526-011-9426-y
- Description: South Africa has some of the most eutrophic aquatic systems in the world, as a result of the adoption of an unnecessarily high 1 mg l-1 phosphorus (P) standard for all water treatment works in the 1970 s. The floating aquatic macrophyte, water hyacinth (Eichhornia crassipes (Mart.) Solms (Pontederiaceae), has taken advantage of these nutrient rich systems, becoming highly invasive and damaging. Despite the implementation of a biological control programme in South Africa, water hyacinth remains the worst aquatic weed. A meta-analysis of published and unpublished laboratory studies that investigated the combined effect of P and nitrogen (N) water nutrient concentration and control agent herbivory showed that water nutrient status was more important than herbivory in water hyacinth growth. Analysis of long-term field data collected monthly from 14 sites around South Africa between 2004 and 2005 supported these findings. Therefore, the first step in any water hyacinth control programme should be to reduce the nutrient status of the water body.
- Full Text:
- Date Issued: 2011
- Authors: Coetzee, Julie A , Hill, Martin P
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69263 , vital:29474 , https://doi.org/10.1007/s10526-011-9426-y
- Description: South Africa has some of the most eutrophic aquatic systems in the world, as a result of the adoption of an unnecessarily high 1 mg l-1 phosphorus (P) standard for all water treatment works in the 1970 s. The floating aquatic macrophyte, water hyacinth (Eichhornia crassipes (Mart.) Solms (Pontederiaceae), has taken advantage of these nutrient rich systems, becoming highly invasive and damaging. Despite the implementation of a biological control programme in South Africa, water hyacinth remains the worst aquatic weed. A meta-analysis of published and unpublished laboratory studies that investigated the combined effect of P and nitrogen (N) water nutrient concentration and control agent herbivory showed that water nutrient status was more important than herbivory in water hyacinth growth. Analysis of long-term field data collected monthly from 14 sites around South Africa between 2004 and 2005 supported these findings. Therefore, the first step in any water hyacinth control programme should be to reduce the nutrient status of the water body.
- Full Text:
- Date Issued: 2011
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