Ecological recovery of populations of vulnerable species driving the risk assessment of pesticides
In the present literature review, we compiled the available scientific information on the ecological recovery of populations of vulnerable species driving the risk assessment of pesticides in the context of reviewing the aquatic and terrestrial guidance documents (SANCO/3268/2001 (EC 2001) and SANCO/10329/2002 (EC 2002)). We reviewed more than 3900 studies on aquatic invertebrates, aquatic microbes, algae, aquatic plants, fish, amphibians, reptiles, and terrestrial microbes, non-target terrestrial plants, non-target terrestrial arthropods including honeybees, non-arthropod invertebrates, birds and mammals, and finally extracted 200 studies suitable for this review. The comparability of the different studies was generally low making it difficult to identify a firm link between recovery time and responsible parameters. Based on the evaluated literature and general ecological knowledge, the following general conclusions can be given:
- Based on the results for aquatic invertebrates, most species recover within five generation times. The absolute time of internal recovery depends strongly on the reproduction capacity.
- Migration from uncontaminated areas is a main driver for external recovery. In many studies including such re-colonization sources recovery occurred within one generation. Especially taxa with a non-synchronised life cycle make efficient use of external recovery.
- If recovery from external sources is assumed, it has to be ensured that the magnitude of re-colonization is a realistic estimation in landscapes heavily influenced by agriculture.
- Environmental stress generally acts in addition or synergistically to pesticide stress and hence recovery has to be evaluated within the ecological context. This is especially true for endangered species that are under particular stress.
- Indirect effects based on competition and predation can play an important role on effect magnitude and recovery time.
- Upscaling of laboratory results for recovery must be related to realistic exposure scenarios of pesticides mixtures within a year and also long-term exposure profiles over multiple years.