The effects of cadmium and nickel on embryonic and larval development of Chinese carp

The effects of Cd and Ni on Chinese carp embryos and larvae were studied. Cd or Ni was administered to the fish throughout their embryonic, larval, or both developmental stages. At the end of the embryonic period, the embryos' survival, hatching time, size, and quality of newly hatched larvae were assessed. After hatching, larvae from the control and Cd or Ni-exposed groups were immediately switched to clean water, Cd or Ni solutions. The findings revealed that embryonic exposure to Cd and Ni cause lower embryonic survival and increased the incidence of body deformities and mortality in freshly born larvae, as well as delayed hatching. The Cadmium was more toxic than Nickel to carp embryos and larvae. Even when larval development took place in clean water, exposure to metals during the embryonic period had a negative impact on larval performance. In continuous Ni exposure, embryonic exposure to Ni decreased the harmful effects of metal on larvae compared to non-pre-exposed fish, but no similar effect was shown in Cd exposure. The findings suggest that even a brief exposure to Cd or Ni during the early development of fish might have a negative impact on the recruitment. Freshly born larvae (frequency of body deformities and larvae dead soon after hatching) were the most responsive to poisoning with both metals among the evaluated endpoints. Embryos were more vulnerable to Ni intoxication than larvae, while both phases were equally susceptible to Cd.

Keywords:

Chinese carp , embryos , Larvae , Heavy metals , Toxicity , Bone deformities , Developmental stages