Effects of cadmium chloride on the development of rainbow trout Oncorhynchus mykiss early life stages

The sub‐chronic (28–56 days) effects of exposure to low concentrations of cadmium (Cd; 0·05, 0·25, 0·50 and 2·50 μg l −1 ) shortly following fertilization on embryos, larvae and juvenile rainbow trout Oncorhynchus mykiss were examined. Premature hatching occurred at lower concentrations (0·05 and 0·25 μg l −1 Cd), however, delayed hatching was seen in the 2·50 μg l −1 Cd group, with >90% of hatching occurring on the last day of the hatching period. Larval growth was negatively affected by Cd exposure in a concentration‐dependent manner. Larvae exposed to 2·50 μg l −1 Cd were 13·9 ± 0·8% shorter in total length ( L T ) and weighed 22·4 ± 3·5% (mean ± s . e .) less than controls at the end of the exposure period. Plasma sex steroid concentrations (oestradiol in juvenile females and 11‐ketotestosterone in juvenile males) were elevated (four‐ to 10‐fold over controls) in exposed fish in both males and females, following 28 days of exposure to 0·05, 0·25 and 0·50 μg l −1 Cd, respectively. These results suggest that environmentally realistic concentrations (in the μg l −1 range) of Cd can affect the development of O. mykiss impacting embryos, larvae and juvenile fish.