Selecting and testing ecologically relevant macrophytes and endpoints in mesocosm studies
Aquatic macrophytes play an ecologically important role in the ecosystem by providing shelter, food and performing essential biological and ecological functions. Aquatic freshwater mesocosms are designed to represent edge of field water bodies by creating a habitat that will support communities of aquatic macrophytes, algae, zooplankton and macroinvertebrates in a contained system. Therefore, the macrophytes included in these systems should reflect the communities found in the natural environment.
The EFSA guidance document on tiered risk assessment for plant protection products (PPP) for aquatic organisms in edge-of-field surface waters, makes recommendations for a minimum of 8 sensitive/vulnerable taxa with acceptable minimum detectable difference (MDD) values to be tested. However, there is little guidance on selecting representative macrophytes that will survive in these systems, or on the selection of appropriate endpoints that will provide regulatory acceptable data. In addition, the limited number of standard macrophyte laboratory tests makes it challenging to determine which species may be sensitive to any given stressor.
The aim of this presentation is to share our expertise on the selection of macrophyte species and techniques for assessing plant growth and health in mesocosm studies. We hope that by sharing our considerations for macrophyte selection and endpoint evaluation in mesocosm studies we can open up the discussion on the relevance of mesocosm studies, particularly within the future of risk assessment for macrophyte communities. We will also demonstrate the CEA sloped mesocosm design as a reference study in order to derive more reliable and robust population and community level endpoints using macrophytes as an example. These results can be used to inform the experimental design of future macrophyte mesocosm studies such that the results meet the EFSA requirements for sensitive/vulnerable taxa with acceptable MDD values for regulatory use.
The slides from the presentation are available for free download.