title: Effects of a sublethal pesticide exposure on locomotor behavior: a video-tracking analysis in larval amphibians.
abstract: Organochlorine pesticides such as endosulfan have been shown to have both lethal and sublethal effects on amphibians. In this context, behavioral endpoints have proved their usefulness in evidencing impacts of such chemicals at environmental concentrations that do not necessarily cause mortality. The recent development of video-tracking technologies now offers the possibility of accurately quantifying locomotor behaviors. However, these techniques have not yet been applied to evaluating the toxicity of pesticides in amphibians. We therefore aimed at determining the potential toxicity of endosulfan on endpoints associated with locomotion after short-term environmental endosulfan exposure in Rana temporaria tadpoles and at using these data as warning systems for survival alterations after a longer exposure. To this end, we analyzed video-tracks of 64 tadpoles (two pesticide treatments: 5 and 50 μg L(-1), one control and one solvent-control) with Ethovision XT 7 software. The highest endosulfan concentration had a significant effect on all four behavioral endpoints. Contaminated tadpoles traveled shorter distances, swam less often, at a lower mean speed, and occupied a less peripherical position than control tadpoles. The lowest endosulfan concentration had similar but lower effects, and did not affect mean speed during swimming. Survival was reduced only after a long-term exposure to endosulfan and was associated with short-term behavioral dysfunctions. These results show that endosulfan strongly affects the behavioral repertory of amphibian tadpoles, but in different ways depending on concentration, thus suggesting that the pesticide has complex modes of action. Given the importance of locomotion and space use in tadpole success in their aquatic environment, these results confirm the toxic action of endosulfan. By highlighting effects before mortality markers, video-tracking systems also show their potential as sentinels of sublethal effects of pesticides.
authors: Laboratory of Fish and Amphibian Ethology, Behavioural Biology Unit, Department of Biology, Ecology, and Evolution, University of Liège, 22 Quai van Beneden, 4020 Liège, Belgium. Mathieu.Denoel@ulg.ac.be
authors: Mathieu
authors: M
authors: Denoël
authors: Sylvie
authors: S
authors: Libon
authors: Patrick
authors: P
authors: Kestemont
authors: Catherine
authors: C
authors: Brasseur
authors: Jean-François
authors: JF
authors: Focant
authors: Edwin
authors: E
authors: De Pauw
mesh_terms: D000818:Animals; D004726:Endosulfan / Q000494:pharmacology* / Q000633:toxicity; D004781:Environmental Exposure / Q000009:adverse effects*; D007814:Larva / Q000187:drug effects / Q000502:physiology; D008124:Locomotion / Q000187:drug effects*; D010575:Pesticides / Q000494:pharmacology* / Q000633:toxicity; D011896:Rana temporaria / Q000254:growth & development / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical; D004726:Endosulfan