Competition of zinc, cadmium and calcium for binding sites in sperm of trout and carp

Document Type: Short paper


Green Research Center, University of Qom, Qom, Iran


Heavy metal pollutions of aquatic ecosystems have already raised many concerns on aquatic
organisms’health and survival especially on their sperm. The effects of a single metal on sperm may be totally
different from cocktail of several metals because of their interactions, so the effects of zinc, cadmium and
calcium on the trout and carp sperms and their competition have been examined by incubation of different
concentrations of cold heavy metals with a radioactive competing metal. The results showed that radioactive
65Zn and 109Cd were not displaced from the trout sperm by calcium even at 3000 ppm concentration but
radioactive cadmium was displaced equally well by cadmium or zinc, with a decrease in pellet activity to 38
and 37% of control values (0 ppm concentration) at 3000 ppm concentration, respectively in trout. Calcium
was replaced by non-radioactive and radioactive zinc and cadmium as well as by calcium. The findings
confirmed that at least part of heavy metals toxicity (especially cadmium) on fish sperm could be due to
displacement of essential zinc and calcium. Both trout and carp sperms showed a similar pattern.