RELATIONSHIPS BETWEEN FREE CUPRIC ION CONCENTRATIONS IN SEA WATER AND COPPER METABOLISM AND GROWTH IN CRAB LARVAE

¹ Molecular Ecology Institute, California State University, Long Beach, California, 90840 and Duke University Marine Laboratory, Beaufort, North Carolina, 28516
² Molecular Ecology Institute, California State University, Long Beach, California, 90840 and Department of Biology, California State University, Long Beach, California, 90840

Crab larvae (Rhithropanopeus harrisiiere exposed to a range of free cupric ion concentrations, [Cu²⁺], regulated in sea water by a metal chelate buffer system. We found a biphasic relationship between intracellular copper distribution and [Cu²⁺] in sea water. At [Cu²⁺] within the ambient range (10^-12.4 to 10^-10.6 M), cytosolic copper was associated with both metallothionein (MT) and high molecular weight (HMW) ligands, and was independent of external [Cu²⁺]. At higher [Cu²⁺], copper was also associated with very low molecular weight (VLMW) ligands, and accumulated in this ligand pool and the MT pool as external [Cu²⁺] increased. In marked contrast, copper in the HMW ligand pool did not correlate with [Cu²⁺] in sea water over the entire range of exposures. Reductions in larval growth occurred at greater than estimated ambient [Cu²⁺] and correlated with copper accumulation in the MT and VLMW pools.