Influence of cadmium on the respiratory function of the grass carp Ctenopharyngodon idella

The effect of 96 h exposure to sublethal cadmium concentrations on oxygen consumption rate (VO2 mg h-1) and oxygen extraction efficiency (OEE' %) was determined in juvenile Ctenopharyngodon idella acclimated to 26, 29 and 32 °C for at least two weeks. The relationships among the physiological rates (VO2 and OEE'), body weight and temperature, were fitted by second order polynomial models; the response surfaces generated allowed the evaluation of stress induced by the interaction of those variables. Both VO2 and OEE' invariably increased as temperature increased. In small animals kept in 0.5 mg Cd L-1, the VO2 increase was compensated by a proportional increase in OEE', whereas in larger fishes (>1 g) no compensatory response was observed. Both small and large fishes were unable to compensate for a higher VO2 when exposed to higher cadmium concentration. It is concluded that OEE' in young fish is an early response of stress due to sublethal cadmium exposure.; The effect of 96 h exposure to sublethal cadmium concentrations on oxygen consumption rate (VO2 mg h-1) and oxygen extraction efficiency (OEE′ %) was determined in juvenile Ctenopharyngodon idella acclimated to 26, 29 and 32 °C for at least two weeks. The relationships among the physiological rates (VO2 and OEE′), body weight and temperature, were fitted by second order polynomial models; the response surfaces generated allowed the evaluation of stress induced by the interaction of those variables. Both VO2 and OEE′ invariably increased as temperature increased. In small animals kept in 0.5 mg Cd L-1, the VO2 increase was compensated by a proportional increase in OEE′, whereas in larger fishes (>1 g) no compensatory response was observed. Both small and large fishes were unable to compensate for a higher VO2 when exposed to higher cadmium concentration. It is concluded that OEE′ in young fish is an early response of stress due to sublethal cadmium exposure.