The role of eutrophication in the biological control of water hyacinth, Eichhornia crassipes, in South Africa
- 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 A meta-analysis of published and unpublished laboratory studies that investigated the combined effect of P and nitrogen (N) water nutrient concentration and control agent herbivory showed that water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.
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- Date Issued: 2011
Pet stores, aquarists and the internet trade as modes of introduction and spread of invasive macrophytes in South Africa
- 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.
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- Date Issued: 2011