Some effects of certain metals on development and mortality within the moult cycle of crangon crangon (L.)

Crangon crangon (L.) (Crustacea: Decapoda) were subjected to three metals (Cd, Cu and Zn) at respective concentrations (0·35, 1·6 and 14·4mg/litre) that would induce 50% mortality in 5–6 days. Significantly different (P < 0·05) rates of mortality occurred in the three groups, although their ET₅₀'s were almost identical. No moultstage-dependent mortality was observed for Cd, but in Cu and Zn the post-moult stages (A and B) were more susceptible than either the intermoult (C_a and C_b) or premoult (D₀–D₄) stages.No significant (P> 0·05) sex- or size-dependent mortality was evident at the tested concentrations of these metals.Feeding and ecdysis were inhibited in all metals after day 3 and development from one moult-stage to the next was greatly reduced in Cd.Possible modes of toxicity have been discussed in terms of the physiological condition inferred from the moult-stage at the time of death.