Acclimation to Copper by Rainbow Trout,Salmo gairdneri: Physiology

Abstract

Juvenile rainbow trout (Salmo gairdneri) were exposed to 55 μg copper∙L−1for 28 d and then transferred to uncontaminated water for 7 d. Whole body sodium concentration and sodium uptake (Jin) were measured at weekly intervals; Jinwas measured at various Na+concentrations and kinetic parameters estimated. After 24 h of copper exposure, the maximum rate of sodium uptake (Jmax) was inhibited by 55%, the affinity for sodium (Km) reduced by 49%, and whole body Na+decreased by about 12.5%. After 7 d of exposure, whole body Na+had returned to control values, but Jmaxwas still inhibited by 41%. Recovery of whole body Na+occurred largely by a reduction of sodium efflux (Jout). Both Jmaxand Kmcontinued to recover until day 28, at which time Jinhad returned to control values. We conclude that acclimation to sublethal copper depends on changes in both Na+transport and permeability.