THE USE OF METABOLISM TO EVALUATE THE TOXICITY OF CADMIUM AND ZINC ON THE Litopenaeus schmitti ACCORDING TO THE SALINITY

Penaeid shrimps are important resources for worldwide fisheries and aquaculture. In Brazil, L. schmitti 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 purp ose of the present study was to detect the acute toxicity of Cd and Zn to L. schmitti and to investigate their effects on oxygen consumption and ammonium excretion in different salinity, which have not been carried out in this species before. First of all, we examined the acute toxicity of Cd and Zn to L. schmitti 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 54.71% and 60.71%, respectively, relative to the control. However, after separate exposure to Cd and Zn, elevations in ammonium excretion were obtained, which were 89.47% and 84.21% higher than the control, respectively. The results shown that Cd and Zn performs higher toxicities to L. schmitti at lower salinitie