Cumulative effects of road de-icing salt on amphibian behavior.
Despite growing evidence of the detrimental effect of chemical substances on organisms, limited research has focused on changes in behavioral patterns, in part due to the difficulties to obtain detailed quantitative data. Recent developments in efficient computer-based video analyses have allowed testing pesticide effects on model species such as the zebrafish. However, these new techniques have not yet been applied to amphibians and directly to conservation issues, i.e., to assess toxicological risks on threatened species. We used video-tracking analyses to test a quantitative effect of an environmental contaminant on the locomotion of amphibian tadpoles (Rana temporaria) by taking into account cumulative effects. Because recent research has demonstrated effects of de-icing salts on survival and community structure, we used sodium chloride in our experimental design (25 replicates, 4 concentrations, 4 times) to test for an effect at the scale of behavior at environmentally relevant concentrations. Analysis of 372 1-h video-tracks (5 samples/s) showed a complex action of salts on behavioral patterns with a dose and cumulative response over time. Although no effects were found on mortality or growth, the highest salt concentrations reduced the speed and movement of tadpoles in comparison with control treatments. The reduced locomotor performance could have detrimental consequences in terms of tadpoles' responses to competition and predation and may be an indicator of the low concentration effect of the contaminant. On one hand, this study demonstrates the usefulness of examining behavior to address conservation issues and understand the complex action of environmental factors and, more particularly, pollutants on organisms. On the other hand, our results highlight the need of new computerized techniques to quantitatively analyze these patterns.
Denoël
Mathieu
M
Laboratory of Fish and Amphibian Ethology, Behavioural Biology Unit, Department of Environmental Sciences, 22 Quai van Beneden, 4020 Liège, Belgium. Mathieu.Denoel@ulg.ac.be
Bichot
Marion
M
Ficetola
Gentile Francesco
GF
Delcourt
Johann
J
Ylieff
Marc
M
Kestemont
Patrick
P
Poncin
Pascal
P
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D007814:Larva / Q000187:drug effects; D011896:Rana temporaria / Q000254:growth & development / Q000502:physiology*; D012965:Sodium Chloride / Q000633:toxicity*; D016019:Survival Analysis; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D012965:Sodium Chloride