Amphibian populations are declining worldwide and many species are considered as threatened on the red list of the International Union for Conservation of Nature (IUCN).
Among factors like loss of habitats and climate change, pollution may play an important role in this decline. In particular, in pond-breeding amphibians, individuals can be exposed to chemicals during their aquatic (i.e. egg and larvae) life stages. After metamorphosis, juveniles and adults can also be exposed to chemicals in the air and soil. At both stages, the highly permeable skin of amphibians makes them particularly sensitive to toxic molecules.
Currently, risk assessment procedures for both the registration of chemicals and the determination of environmental quality criteria rarely consider the toxicity to amphibians. One reason is that few robust and reproducible methods exist to determine the effects of chemicals on these species. Secondly, and as a consequence of the first point, there is minimal literature on amphibian ecotoxicity.
During my PhD, I developed a 8-day protocol and tested it using two organophosphate pesticides, the diazinon and the chlorpyrifos. This protocole imply the measurement of X. laevis larvae swiming behavior along with biochemical, morphological and lige-history traits. On this purpose I conceived a home-made setting allowing for taking videos of swimming larvae. Basically, the setting is a box with 6 enlightened wells, each containing 12 cm petri dishes filled with water. In each petri dishes is placed a larvae. At the bottom of the box is a camera and swimming behavior is measured for 10 min. The setting would be nothing with the computing solution for quantifying behavior so I wrote a R script for automating video conversion, cropping and particle tracking. All the results were analysed taking profit of recent generalized linear mixed effects models.
Boualit, L., Cayuela, H., Cattin, L., & Chèvre, N. The Amphibian Short Term Assay (ASTA): Evaluation of a New Ecotoxicological Method for Amphibians Using Two Organophosphate Pesticides Commonly Found in Nature. Assessment of Biochemical, Morphological and Life History Traits. Environmental Toxicology and Chemistry.
Cayuela, H., Prunier, J. G., Laporte, M., Gippet, J. M., Boualit, L., Guérold, F., … & Jacob, G. (2021). Demography, genetics, and decline of a spatially structured population of lekking bird. Oecologia, 195(1), 117-129.
Cayuela, H., Boualit, L., Laporte, M., Prunier, J. G., Preiss, F., Laurent, A., ... & Jacob, G. (2019). Kin-dependent dispersal influences relatedness and genetic structuring in a lek system. Oecologia, 191(1), 97-112.
Boualit, L., Pichenot, J., Besnard, A., Helder, R., Joly, P., Cayuela, H., 2019. Environmentally mediated reproductive success predicts breeding dispersal decisions in an early successional amphibian. Animal Behaviour 149, 107–120. https://doi.org/10.1016/j.anbehav.2019.01.008
Cayuela, H., Boualit, L., Arsovski, D., Bonnaire, E., Pichenot, J., Bellec, A., … & Besnard, A. (2016). Does habitat unpredictability promote the evolution of a colonizer syndrome in amphibian metapopulations?. Ecology, 97(10), 2658-2670.
Cayuela, H., Arsovski, D., Boitaud, S., Bonnaire, E., Boualit, L., Miaud, C., … & Besnard, A. (2015). Slow life history and rapid extreme flood: demographic mechanisms and their consequences on population viability in a threatened amphibian. Freshwater biology, 60(11), 2349-2361.