Aquatic macrophyte risk Assessment: current status anbd future challenges

G.H.P. Arts, J. Davies, M. Dollinger, J. Giddings, M. Hanson, K. Knauer, U. Hommen, S. Loutseti

Research output: Chapter in Book/Report/Conference proceedingAbstract


Aquatic macrophytes fulfill critical functions in ecosystems, contributing to structure and function. Aside from the floating, non-sediment rooting duckweed species (Lemna spp.), other aquatic macrophytes are not routinely considered in standard risk assessments for chemicals in Europe yet. In the pesticide regulation (1107/2009/EC) Lemna spp. are the Tier 1 test species. However, they differ from rooted and submerged macrophytes, most markedly in their short generation time and free-floating growth form. The concern, that risk assessments based on endpoints derived from tests with Lemna may not be protective for other macrophyte species, was a driving reason for the workshop “Aquatic Macrophyte Risk Assessment for Pesticides” (AMRAP) in 2008. The participants concluded that the risk assessment based on data obtained from Lemna studies may not be sufficiently protective in certain cases. Additional triggers for further testing were defined including the specific mode of action of pesticides and the possible exposure of macrophytes via sediment. Therefore, an additional Tier 1 test with a rooted dicotyledonous macrophyte, Myriophyllum spp., was proposed. Test protocols for Myriophyllum sp. are currently being ring-tested in order to become a standardized OECD test. If concern over the safety of a pesticide is still present after Tier 1 testing and risk evaluation, higher-tier assessments may be performed through e.g. the generation of further macrophyte species data for use in species sensitivity distributions (SSDs), or by conducting multi-species tests or microcosm and mesocosm studies. Species Sensitivity Distribution analyses on 14 compounds performed by a working group with Aquatic Macrophyte Ecoxicology Group (or AMEG, which emerged out of the AMRAP workshop) found that effects on L. gibba and the four algal species required for US pesticide registration are in most cases protective for rooted and submerged macrophyte species. Exceptions can generally be predicted based on the mode of action of the chemical. In European pesticide regulation (1107/2009/EC) Myriophyllum spp. and Glyceria maxima have recently been proposed as additional test species. Other regulatory frameworks include the Water Framework Directive (WFD) which aims to achieve a ‘good’ ecological and chemical status for all surface waters in the EU. Attainment of this status requires that chemical concentrations meet Environmental Quality Standards based on ecotoxicological data. The integration of climate change and how it can modify our understanding of ecosystems and effects in the field for risk evaluation poses additional challenges for aquatic macrophyte risk assessment. For example, modeling tools are needed to predict the effects of changing water temperature on plant growth and development and changing hydrological regimens might change exposure. While the potential effects and manner in which climate change might be manifest in freshwater ecosystems are still being discussed and quantified, the integration of these aspects into risk assessments is missing. Working on these concepts and translating patterns into robust aquatic macrophyte risk assessments is one of the challenging topics for future research.
Original languageEnglish
Title of host publicationInnovative approaches for the management of environmental risks from plant protection products, Montpellier, France, 26 - 28 October, 2011
Place of PublicationMontpellier, France
Publication statusPublished - 2011
EventInnovative approaches for the management of environmental risks from plant protection products, A joint Eurequa-PEER Scientific Conference, Montpellier, France -
Duration: 26 Oct 201128 Oct 2011


ConferenceInnovative approaches for the management of environmental risks from plant protection products, A joint Eurequa-PEER Scientific Conference, Montpellier, France


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