The effect of cadmium and cadmium/copper mixture during the embryonic development on deformation of common carp lavae.

The aim of present study was to estimate the effect of single and binary combinations of cadmium with copper during the embryonic development on hatching success and quality of common carp larvae. The results were compared to those obtained after copper exposure, during the same experiment (Witeska and Ługowska 2004). The study was done on common carp newly hatched larvae, the embryonic development of which took place at 0.2 mg/dm3 of cadmium (Cd group) and 0.2 (0.1+0.1) mg/dm3 mixture of cadmium and copper (CdCu group), or in clean tap water (control – K group). Newly hatched larvae were counted and inspected, and for 20 days from hatching reared under control conditions. The results show that cadmium (0.2 mg/dm3) reduced the success of hatching and caused an increase of number of deformed larvae among the newly hatched ones. The results obtained in the same experiment after copper exposure (Cu 0.2 mg/dm3) (Witeska and Ługowska 2004) indicate that toxic effect of this metal on hatching and quality of larvae was stronger than the effect of cadmium. No differences in effect of cadmium exposure (0.2 mg/dm3) and it’s co-exposure with more toxic copper (0.1 mg/dm3 Cd+0.1 mg/dm3 Cu) on hatchability and frequency of deformations were observed. These results indicate metal interaction, which in this case probably was antagonistic. Metal exposure decreased survival of fed and starved normal and deformed larvae. Fish died gradually just after hatching. The comparison of effect of cadmium and Cd+Cu mixture shows that the mixture of both metals was more toxic than cadmium alone, but not stronger than copper alone. These data suggest that effect of metal mixture can be additive. Detailed classification of deformed larvae in the present study showed that cadmium alone and in co-exposure with copper caused the same types of larval deformations: vertebral curvatures, body and yolk sac deformations. Under optimal conditions in laboratory culture, vertebral deformations may recover