SUSCEPTIBILITY OF LARVAL AND JUVENILE INSTARS OF THE SAND CRAB, PORTUNUS-PELAGICUS (L), TO SEA-WATER CONTAMINATED BY CHROMIUM, NICKEL OR COPPER

The acute toxicities of Cu2+, Ni2+ and Cr(VI) in sea water to larval l ife stages of the sand crab, Portunus pelagicus, were determined in a laboratory study and compared with published data for the toxicity of heavy metal cations to this species. This showed the relative acute to xicities to be in the order Cu2+ > Cd2+ > Zn2+ > Ni2+ > Cr(VI). Sublet hal effects attributable to exposure to sea water contaminated by some of these cations were investigated for both larval and juvenile crab life stages. The effects quantified were inhibition of larval moulting , increase in the duration of development period, and reduced size ach ieved by successive juvenile crab instars. In each case, the chronic l evels of cation contamination in seawater associated with these effect s exceeded the Australian guidelines for the protection of marine aqua tic ecosystems, but in some cases the safety margin was less than an o rder of magnitude. In addition, bioconcentration relationships for Cr were determined on a whole-animal and an exoskeleton basis.