Effects of previous sublethal pulse to ammonium nitrate on mortality and total length on Epidalea calamita larvae

Ammonium nitrate is one of the most widespread contaminants related with the viability of natural amphibian populations. In this study we have evaluated in terms of mortality and total length the effects that a previous sublethal pulse to ammonium nitrate generates in Epidalea calamita. Experiments were divided in two phases. In the first one, tadpoles were exposed to two different treatments, with and without a low ammonium nitrate concentration (22 mg NH4NO3 L−1). The second phase consisted in static toxicity experiments from both origin treatments with five different nominal concentrations (0, 22, 45, 90 and 180 mg NH4NO3 L−1). Results showed that tadpoles that had experienced a previous sublethal exposure showed a negative effect on survival (57% of reduction in the LC50 value) and total length, throughout an increase in their sensitivity. These results could help us to understand the situation of amphibian populations inhabiting aquatic ecosystems exposed to discontinuous and variable pulses of pollutants.

► We have evaluated the effects of sequential exposures to nitrate on amphibian larvae.
► We examined changes in two endpoints, mortality and total length.
► Larvae which were sequentially exposed showed a reduction in their LC50 values.
► Amphibian tolerance to nitrate depends on previous exposures.