Comparative toxicity of dissolved metals to early larval stages of Palaemon serratus, Maja squinado, and Homarus gammarus (Crustacea : Decapoda)

The acute lethal toxicities of mercury, copper, and cadmium to the first la rval stage of the prawn (Palaemon serratus), spider crab (Maja squinado), a nd lobster (Homarus gammarus) were tested. Chromium was also tested with th e prawn. Mortality was recorded after 48 h (for lobster) or 72 h (for other species) incubation at 18 degrees C, and the median lethal concentrations (LC50 +/- 95% confidence intervals) per individual and per mass unit were c alculated. The LC50 values were, 74 mu g Hg/L, 3,304 mu g Cu/L, 1,686 mu g Cd/L, 12,486 mu g Cr/L for prawn; 72 mu g Hg/L, 50 mu g Cu/L, 158 mu g Cd/L for spider crab; and 48 mu g Hg/L, 46 mu g Cu/L, 34 mu g Cd/L for lobster. Therefore, larvae of spider crab and lobster were markedly more sensitive than prawn to heavy metals and thus more suitable to use in seawater qualit y bioassays. Of these two species, spider crab is recommended due to its ab undance, easier maintenance, and higher fecundity. The mercury LC50 values for different larval stages of P. serratus (zoea I, II, V, and VI) were obt ained, and no ontogenetic change in sensitivity to the metal could be detec ted.