| Onderwerp: |
Development, improvement and validation of toxicity test methods for studying the effects of toxicants on submerged macrophytes.
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Vereiste opleiding en kennis:
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WO Biologie, Toxicologie, Milieukunde of Natuurbeheer, rijbewijs is gewenst |
Status (stage of afstudeervak):
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Stage of afstudeervak, HBO + WO-niveau |
Periode/duur:
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4 tot 6 maanden (of langer) |
| Inhoudelijke omschrijving: |
Submerged macrophytes are an important structural and functional element of aquatic ecosystems. In the environmental risk assessment procedures for pesticide registration however, they are only considered fragmentarily. In the risk assessment the floating macrophyte Lemna is considered a model organism for macrophytes. Tests with the floating macrophyte Lemna are required for herbicides. A test with a submerged macrophyte is only required for herbicides if risks to aquatic plants (i.e. Lemna) are identified. In the revision of the guideline, all compounds with herbicidal mode of action (including some fungicides) have to be tested with the standard macrophyte species Lemna. If Lemna is the most sensitive standard test organism, a test with a submerged macrophyte has to be performed additionally.
In 2008 a workshop was held in Wageningen on the risk assessment of aquatic macrophytes to pesticides (AMRAP Aquatic Macrophyte Risk Assessment for Plant Protection Products). The workshop recommends an adapted risk assessment scheme and identifies a number of gaps in knowledge and needs. So is more research necessary on the most optimal growth conditions for several aquatic macrophytes in the laboratory. The optimization of the sediment to achieve optimum macrophyte growth in the laboratory is one of the important research questions.
In 2009, the following student research topics can be chosen:
- Optimization of the sediment for laboratory toxicity experiments: testing of an artificial sediment, testing of an artificial sediment incubated with a nutrient medium and testing of an artificial sediment with a slow-release-fertilizer (Osmocote).
- What is the influence of the length of the pre-growth period of the macrophytes on their sensitivity ? Does root development influence their sensitivity ?
- There is a lack of knowledge about the sensitivity of seeds or tubers to pesticides, for example seeds of Myriophyllum or tubers of Potamogeton pectinatus. There is a need for experimental guidance and a lack of information.
- Physiological aspects in macrophyte toxicity tests (in cooperation with other departments of Alterra and WUR and plant physiologists). Is it possible to measure internal concentrations in macrophytes, which methods, are internal concentrations related to effects ?
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