Amphibians in agricultural landscapes: chemical landscape fragmentation implemented in a habitat modeling approach
Final Report Abstract
The overarching goal of this study was to develop an empirical understanding of the population-level impacts of a potential chemical landscape fragmentation in three amphibian species with different dispersal capabilities: the common toad, the common frog and the palmate newt. Within this project we demonstrated with an extensive telemetry study that common toads are using vinicultures as habitat, however, toads tend to avoid arable fields and prefer non-cultivated areas. This avoidance behavior was moderately confirmed in a lab experiment using arena-choice settings. However, also a weakly pronounced avoidance of agricultural land might contribute to a decreased gene flow between breeding ponds and an increased isolation of subpopulations. On the other hand, the lack of an avoidance might increase the pesticide exposure risk of amphibians in agricultural landscapes with potentially lethal effects and consequently may also lead to a chemical landscape fragmentation. In a semi-field study we showed that higher pesticide exposed populations suffer from long-term reproductive impairments. In combination with acute toxicity effects, the detected sublethal effects pose a serious threat on amphibian populations in agricultural landscapes that might also shape the genetic structure of populations in the longer term. However, our genetic data for all three study species exhibited a higher gene flow among subpopulations as initially hypothesized. We conclude that agricultural ponds are valuable amphibian habitats necessary for the metapopulation connectivity, and that conservation effort should aim to preserve them. Based on the knowledge obtained in this project, Christoph Leeb contributes to the COST action PERIAMAR as external expert in amphibian ecotoxicology in the working group "Ecosystem-level assessment". This research project received media coverage with TV-clips on amphibians and pesticides broadcasted on several German public broadcasting corporations (e.g. ARD - 3.9.16 - http://www.ardmediathek.de/tv/W-wie-Wissen/Amphibiensterben-Pestizide-im-Visier-de/Das-Erste/Video?bcastId=427262&documentId=37504900), articles in news papers (e.g. Rheinpfalz - 14.03.3021), as well as institutional coverage through regular research articles on the EcotoxBlog from the University of Koblenz-Landau (http://www.master-ecotoxicology.de/ecotox-blog/tag/theissinger/).
Publications
- (2017). Amphibian population genetics in agricultural landscapes: does viniculture drive the population structuring of the European common frog (Rana temporaria)? PeerJ, 5, e3520
Lenhardt, P. P., Brühl, C. A., Leeb, C., & Theissinger, K.
(See online at https://doi.org/10.7717/peerj.3520) - (2019). Validating buccal swabbing as a minimal-invasive method to detect pesticide exposure in squamate reptiles. Chemosphere, 229, 529-537
Mingo, V., Leeb, C., Fahl, A. K., Lötters, S., Brühl, C., & Wagner, N.
(See online at https://doi.org/10.1016/j.chemosphere.2019.05.025) - (2020). Avoidance behavior of juvenile common toads (Bufo bufo) in response to surface contamination by different pesticides. Plos one, 15(11), e0242720
Leeb, C., Kolbenschlag, S., Laubscher, A., Adams, E., Brühl, C. A., & Theissinger, K.
(See online at https://doi.org/10.1371/journal.pone.0242720) - (2020). Potential pesticide exposure during the postbreeding migration of the common toad (Bufo bufo) in a vineyard dominated landscape. Science of The Total Environment, 706, 134430
Leeb, C., Brühl, C., & Theissinger, K.
(See online at https://doi.org/10.1016/j.scitotenv.2019.134430) - (2021). Pesticide exposure affects reproductive capacity of common toads (Bufo bufo) in a viticultural landscape. Ecotoxicology, 1-11
Adams, E., Leeb, C., & Brühl, C. A.
(See online at https://doi.org/10.1007/s10646-020-02335-9)
