Sublethal maternal pre-exposure of fish to cadmium. Effect on the survivalof the newly hatched alevins

The aim of this study was to determine the effects of the exposure of pregn ant females of a viviparous teleost Cnesterodon decemmaculatus to sublethal Cd solutions on the survival of their offspring. Ovigerous females were ac climated and accomodated in aquaria containing the following solutions: art ificial freshwater medium (AFW) and AFW with 25, 50 and 100 mu g Cd2+/L (as chloride). Part of the offspring born from control females was transferred to media containing 25, 50 and 100 mu g/L of cadmium; the rest of the fry stayed in AFW solutions without cadmium. The offspring born from the female s maintained in solutions of cadmium were transferred to aquaria with AFW, and to solutions containing metal at the same concentration as their mother . In all cases mortality was recorded daily for 168 h. The results demonstr ated that the survival of newborn offspring was always related to the conce ntration of Cd2+ to which they were exposed at birth, regardless of the con centration of the metal to which the mother was exposed during its pregnanc y. When exposed to Cd2+, alevins from non-exposed females showed a constant linear death rate while in those from Cd-exposed it resulted exponential.