Endosulfan Effects on Rana dalmatina Tadpoles: Quantitative Developmental and Behavioural Analysis

Endosulfan is an organochlorine pesticide thatwas recently labeled as a persistent organic pollutant, but itis still widely employed, particularly in developing countries.The goal of this study is to evaluate the acute (LC50)and chronic effects (developmental and behavioural traits)of this insecticide on Rana dalmatina tadpoles afterexposure to ecologically relevant concentrations (0.005,0.01, and 0.05 mg/L) by applying video-tracking techniquesto evaluate the quantitative effect of endosulfan onamphibian behavioural patterns. The 96 h LC50 value was0.074 mg endosulfan/L. Tadpoles chronically exposed to0.01 and 0.05 mg endosulfan/L underwent high mortalityrate, decreased larval growth, delayed development, andincreased incidence of malformations, and they did notreach metamorphosis by the end of the experiment.Moreover, tadpoles exposed to these concentrationsexhibited several abnormalities in swimming patterns, suchas shorter distance moved, swirling, resting, and unusualuse of space. The exposure to 0.005 mg endosulfan/L didnot cause any significant effects on behaviour, larvalgrowth, or development, but we observed a significantdecrease in both survival and time to metamorphosis.We showed that developmental abnormalities aredose-dependent and that the pesticide effects could differdepending on the endosulfan concentration and the speciestested. We also validated the hypothesis that behaviouralanalysis, along with the use of new analytical methods,could be a useful tool in amphibian ecotoxicologicalstudies.