The relative sensitivities of different life stages ofIsognomon californicum to cadmium toxicity

Embryos, four different ages of larvae, juveniles, and adults of an Hawaiian bivalve,Isognomon californicum, were exposed to a range of cadmium concentrations at two salinities to determine 48-hr LC50s and to compare the relative sensitivities of the various life stages. The Cd 48-hr LC50s of embryos, 3 day and 10 day old larvae were similar. Older larvae, 24 and 36 days, also showed a similar sensitivity to each other but their LC50s were approximately one order of magnitude higher than those of the younger stages. Newly settled juveniles were less sensitive than embryonic or larval stages and adults were the least sensitive. There was a general trend of increased toxicity with decreased salinity, but salinity effects were not significant with late larvae, juveniles, or adults.