Contrasting effects of ammonium nitrate on tadpole survival, growth and behavior in two common anuran species

Abstract

Extensive fertilizer use often leads to an accumulation of chemicals in waterbodies that are in close proximity to agricultural fields. One such commonly used fertilizer, ammonium nitrate, has been shown to negatively affect anuran survival and behavior. We performed experiments on tadpoles of two amphibian species, the Agile frog (Rana dalmatina) and the Common toad (Bufo bufo), to test the effects of different concentrations (0 mg/L, 50 mg/L, 100 mg/L and 200 mg/L) of ammonium nitrate on survival, growth and movement activity. We also examined whether sensitivity to predator cues might be altered in the presence of ammonium nitrate. Finally, we tested for the capacity of the two species to exhibit avoidance behavior. Overall, we found that the Agile frog is more sensitive to ammonium nitrate than the Common toad in terms of survival, growth and movement activity. Sensitivity to predator cues was not affected by the fertilizer for the Agile frog, but was shown to alter the behavior of Common toads, whose movement activity did not decrease in the presence of predator cues. Neither species showed an avoidance behavior. Our results suggest that ammonium nitrate can have significant effects on Agile frog tadpoles through direct toxicological effects on survival and growth, but also through behavioral effects. For Common toads those effects were less obvious, but were nonetheless shown in terms of growth, activity and predator detection.