Effects of zinc and cadmium on oxygen consumption and ammonium excretion in pink shrimp (Farfantepenaeus paulensis, Pérez-Farfante, 1967, Crustacea).

In Brazil, pink shrimp (Farfantepenaeus paulensis) is an important commercially exploited species and is an ideal animal for studying the impairment caused by the effects of heavy metals that are often detected in coastal areas. The main purpose of the present study was to detect the acute toxicity of cadmium and zinc to F. paulensis and investigate their effects on oxygen consumption and ammonium excretion, investigations that have not been carried out in this species before. First, the acute toxicity of zinc and cadmium to F. paulensis for 24, 48, 72, and 96 h--medium lethal concentration was examined, which resulted in the following values: 9.39, 6.00, 4.88, and 3.31 mg/l for zinc and 2.35, 1.67, 1.26, and 0.83 mg/l for cadmium. Furthermore, we also found that exposure of shrimp to zinc and cadmium caused an inhibition in oxygen consumption of 25 and 32.4%, respectively, relative to the control. In addition, after separate exposure to cadmium and zinc, elevations in ammonium excretion were obtained, which were 42.85 and 51.85% higher than the control, respectively.