Is it possible to extrapolate results of aquatic microcosm and mesocosm experiments with pesticides between climate zones in Europe?

Higher tier studies to assess the environmental risks of pesticides have been performed mainly in Atlantic Central Europe and North America and results of such studies have been extrapolated to other climatic regions such as South Europe (Ramos et al. 2000; López-Mancisidor et al. 2008a). Since climate (e.g., sun hours, rainfall, temperature), agroecosystems (e.g., crop rotation, field size), and edge-of-field surface waters (e.g., hydrology, ecology) in those regions are quite different, it may be expected that exposure profiles and effects of pesticides in surface waters are also different (Tarazona 2005; López-Mancisidor et al. 2008a). It may thus be questionable whether the extrapolation of results from higher tier studies over these regions is justified (Ramos et al. 2000; López-Mancisidor et al. 2008a). On the other hand, it is neither financially nor practically feasible to test a large number of chemicals on a large number of species and communities in different localities (Brock et al. 2006). In the EU, these concerns were acknowledged with the recent adoption of a new regulation concerning the placing of plant protection products on the market (Regulation (EC) No. 1107/2009; EU 2009). According to this regulation, authorizations granted by one Member State should in principle be accepted by other Member States where agricultural, plant health, and environmental (including climatic) conditions are comparable. To this end, three zones with such comparable ecological and climatic conditions were distinguished, namely North, Central, and South (Table 1). Van Wijngaarden et al. (2005a), Van den Brink et al. (2006), and Maltby et al. (2009) reviewed aquatic model ecosystem studies carried out with insecticides, herbicides, and fungicides, respectively. The vast majority of the European studies were conducted in the Central zone, whereas very few studies were reported for both the South and the North zone (Table 1). To account for the lack of studies in the South zone, a research project was initiated in 2010 that started with the set up of an outdoor microcosm facility in Lisbon (Portugal). One of the aims of this facility is to study the possibilities and limitations in the spatial extrapolation of regulatory acceptable concentrations (RACs) derived from outdoor micro-/mesocosm experiments between European climate zones. The present paper aims at summarizing differences in (1) ecology of edge-offield surface waters, (2) exposure conditions to pesticides, (3) direct and indirect effects, and (4) recovery potential in pesticide stressed (semi-)field freshwater ecosystems under South zone compared to Central zone conditions that a priori may be anticipated. Implications for choices related to the experimental design of experiments in Portugal are discussed based on this analysis. Responsible editor: Markus Hecker