EFFECTS OF CADMIUM AND ZINC ON OXYGEN CONSUMPTION AND AMMONIA EXCRETION OF THE SEA-BOB SHRIMP, ACCORDING TO THE TEMPERATURE*

Penaeid shrimps are important resources for worldwide fisheries and aquaculture. In Brazil, Xiphopenaeus kroyeri 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 Cd and Zn to X. kroyeri and to investigate their effects on oxygen consumption and ammonium excretion in different temperatures (25 oC, 20 oC, 15 oC), which have not been carried out in this species before. First of all, we examined the acute toxicity of Cd and Zn to X. kroyeri 24, 48, 72, and 96-h medium lethal concentration (LC50). Furthermore, we also found that exposure of shrimp to Cd and Zn caused an inhibition in oxygen consumption of 52.50% and 52.63%, respectively, relative to the control. However, after separate exposure to Cd and Zn, elevations in ammonium excretion were obtained, which were 85.00% and 89.47% higher than the control, respectively. The results shown that Cd and Zn performs higher toxicities to X. kroyeri at higher temperature.