MECHANISMS FOR ZINC ACCLIMATION IN FRESH-WATER RAINBOW-TROUT

A sublethal effect of zinc exposure in freshwater fish is the inhibiti on of calcium uptake. However, calcium also inhibits zinc uptake and t his inhibition has been found to be competitive (Spry, D.J. & Wood, C. M. (1989). J. Exp. Biol., 142, 425-46). The subject of the acclimation of aquatic animals to metals is well researched, but there is, as yet , no simple answer as to how this acclimation is accomplished. The obj ectives of the present study were to characterize the interactions of zinc on calcium uptake kinetics, and to investigate ifa restoration of calcium influx was associated with zinc acclimation. In addition, the possible involvement of metallothionein and a reduced zinc influx in the acclimation process was studied.