Amphibians are among the most endangered vertebrate classes and 32% of all amphibian species are threatened. One reason for the decline of amphibian populations is the exposure of their aquatic and terrestrial habitats to pesticides. Due to their biphasic life cycle, the poikilothermic way of life and specific skin parameters amphibians differ from other vertebrates, thus being more susceptible to pollutants. In this research project we will use aquatic and terrestrial laboratory and field studies to assess the impact of pesticides on German amphibian species.

Ecotoxicological amphibian studies often use tropical species (especially Xenopus laevis). However, these species can be less sensitive than European species due to specific skin parameters and physiological differences. Thus, a higher sensitivity of native amphibians cannot be excluded. To compare the sensitivity differences among species we aim to collect acute toxicity data (LC50, lethal concentration) for multiple German amphibian species to generate Species Sensitivity Distributions for three environmentally relevant pesticides.

Furthermore, we want to study the effects of additives in pesticide products. To ensure an optimal efficacy to pesticides, active ingredients are combined with additives. Although different products show diverse effects on non-target organisms, additives are so far not evaluated in the registration procedure of pesticides. We will analyze lethal and sublethal effects (oxidative stress, neurotransmitterinhibition) of additives in pesticide products on aquatic and terrestrial developmental stages of the European common frog (Rana temporaria).

Since most pesticides in the environment are present in mixtures, synergistic sublethal effects cannot be excluded after a long-term exposure. Therefore, we want to investigate the sublethal effects of realistic concentrations of pesticide mixtures on the European common frog in a long-term field study. The analyzed endpoints will be oxidative stress, neurotransmitterinhibition, body condition, malformations and behavioral abnormalities.

With these findings the risk of pesticides for German amphibians can be estimated and thus, the protection of amphibians in agricultural landscapes can be improved.

This study is funded by the Scholarship Programme of the German Federal Environmental Foundation.