Cadmium-handling strategies in two chronically exposed indigenous freshwater organisms-the yellow perch (Perca flavescens) and the floater mollusc (Pyganodon grandis)

Along the Cd-exposure gradient, Cd detoxification appeared to be reasonably effective in the bivalve gill and digestive gland, as judged from the protection of the heat-denaturable protein (HDP) fraction. However, in both organs Cd concentrations did increase in potentially metal-sensitive organelles (mitochondria), and malondialdehyde concentrations increased along the exposure gradient in the gills (but not in the digestive gland). Cadmium detoxification seemed less effective in juvenile yellow perch. As total hepatic Cd increased, Cd concentrations increased in all sub-cellular fractions, including the HDP fraction that was well protected in the bivalve. The relative proportions of Cd in the various fractions did not vary appreciably along the exposure gradient and there was no evidence of a threshold exposure concentration below which sensitive metal pools were protected.