Acute toxic effects of cadmium in larvae of the green toad, Pseudepidalea variabilis (Pallas, 1769) (Amphibia: Anura)

Abstract

The environmental impact of cadmium use and its accumulation in nature have increased to alarming levels. This study aimed to morphologically and histologically investigate the acute toxic effects of cadmium on green toad, Pseudepidalea variabilis (Pallas, 1769) larvae. Embryos were obtained from specimens collected in amplexus from nature and kept under laboratory conditions until stage 26, when they were exposed to cadmium (0, 1, 5, 10, 25, and 50 µg L^-1) for 96 h. The LC_10, LC₅₀,and LC₉₀ values of cadmium were calculated to be 26.98, 35.35, and 46.31 µg L^-1, respectively. Our results showed that cadmium had a negative effect on the body size of P. variabilis larvae (over 1 µg L^-1). Histological examination detected a fusion of gill lamellae, liver haemorrhage, oedema in the abdominal cavity, and deformations of pronephric tubules (over 10 µg L^-1). Our findings suggest that the green toad was sensitive to the cadmium treatment, with LC₅₀ values lower than those reported by other studies. Thus, this species could be considered a reliable indicator species of environmental stress in aquatic ecosystem.