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

The aim of this study was to determine the effects of the exposure of pregnant females of a viviparous teleost Cnesterodon decemmaculatus to sublethal Cd solutions on the survival of their offspring. Ovigerous females were acclimated and accomodated in aquaria containing the following solutions: artificial 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 females 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 demonstrated that the survival of newborn offspring was always related to the concentration of Cd2+ to which they were exposed at birth, regardless of the concentration of the metal to which the mother was exposed during its pregnancy. When exposed to Cd2+, alevins from non-exposed females showed a constant linear death rate while in those from Cd-exposed it resulted exponential.