Disturbed ion balance in alevins of Atlantic salmon Salmo salar chronically exposed to sublethal concentrations of cadmium

Abstract

Embryos and alevins of Atlantic salmon Salmo salar were exposed to cadmium concentrations ranging from 0.47 to 300 μg Cd/L from shortly after fertilization to near complete yolk absorption (92 days). Tissue sodium, potassium, calcium, magnesium, and water contents of embryos and alevins were determined at 9-day intervals during this period. Cadmium had no significant effect on the tissue cation or water contents of embryos. Net water uptake by alevins was significantly inhibited at cadmium concentrations ≥0.78 μg Cd/L. Net sodium uptake was significantly inhibited at all concentrations except 79 and 300 μg Cd/L, but because of the concomitant decrease in water uptake there were no significant changes in sodium to water ratios. Net potassium uptake was significantly inhibited at concentrations ≥ 8.2 μg Cd/L and net calcium uptake was significantly inhibited at concentrations ≥ 0.78 μg Cd/L. Tissue magnesium was not affected. Calcification of skeletal elements was inhibited progressively at concentrations ≥ 0.78 μg Cd/L. Low tissue potassium and calcium levels appeared to be responsible for many of the symptoms associated with cadmium poisoning and were probably the immediate cause of death.