Identification and modelling of a representative vulnerable fish species for pesticide risk assessment in Europe

The effect assessments of pesticides on non-target organisms mainly rely on toxicity tests using surrogate species which deliver endpoints regarding the survival, growth and reproduction of test individuals. For aquatic vertebrates (represented by fish) specific protection goals address the survival of individuals and the abundance and biomass of populations. Since individual-level endpoints can easily be measured and are cost-effective, and since testing on field populations is neither ethical nor practical for vertebrates, results of fish toxicity tests should be extrapolated to the population level, at least the measured effects on individual growth and/or reproduction. Ecologically relevant extrapolations can be achieved using population modelling of representatives of vulnerable fish species in the field, focal species, which are not only characterized by their intrinsic sensitivity to stress but also by their susceptibility to pesticide exposure and their population resilience. The conducted research comprehensively identified focal fish species for each of the following types of pesticide effects: juvenile survival, adult survival and reproduction. The susceptibility of fish species to pesticide exposure and their population resilience in case adversely affected were considered for the identification, following a step-wise filtering and matrix modelling approach. Then, an individual-based population model was built for the minnow, the identified focal species for pesticide effects on reproduction i.e. for adverse effects on fecundity, fertility, hatching or larval survival. This model can serve as a non-experimental refinement option whereby it can be used as a virtual laboratory for the assessment of measured effects on reproduction in standard toxicity tests, on the population level of an ecologically relevant fish species. The modelling process was documented following good modelling practice and the applicability of this model to ERA was generically demonstrated. This research was able to lay foundations for the use of population modelling of focal species as a refinement option for ERA of pesticides on fish. Supplementary information additionally provide a rich database on European freshwater fish which can be used for a multitude of research questions