John Wiley & Sons, Ltd.

Salinity and copper interactive effects on Perez's frog Pelophylax perezi

This study intended to assess the influence of salinity on the effects of copper on two life‐stages of Pelophylax perezi. Single and combined effects of salinity (NaCl) and copper on survival, malformations, body length, and biochemical markers (catalase‐CAT, cholinesterases‐ChE, lactate dehidrogenase‐LDH, and glutathione S‐transferase‐GST) of individuals were evaluated in a multifactorial design. Two experiments were performed, one with embryos and the other with tadpoles. Each of these life stages were exposed to individual and combinations of copper (0.0–7.4 mg/L; 0.0–2.4 mg/L, respectively) and NaCl (0.0–10.2 g/L; 0.0–7.4 g/L, respectively) concentrations. Copper alone exerted a higher lethal toxicity to tadpoles (90%; 2.4 mg/L) than to embryos (65%; 7.4 mg/L). Conversely, NaCl alone exerted a higher lethal toxicity to embryos (100%; 6.9 g/L) than to tadpoles (50%; 7.4 g/L). The four lowest tested NaCl concentrations decreased the lethal effects of copper to embryos and the incidence of malformations, but the same outcome was not observed on tadpoles. Regarding enzymatic activities, though significant interaction, between copper and NaCl, were observed for the activity of CAT and LDH in embryo and tadpole, a consistent pattern on NaCl and copper interactive effects was not observed. Obtained results suggest a life‐stage dependency on the effects caused by exposure to the individual chemicals or its combination. Also, it was observed that moderate salinity may have a shield effect against copper lethal toxicity for embryos of P. perezi. These results highlight the need, within ecological risk evaluations, to characterize the sensitivity of amphibian different life stages to individual chemicals but also their combination with other environmental conditions resulting from climate changes. Environ Toxicol Chem © 2013 SETAC

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