Changes in Erythron Organization during Prolonged Cadmium Exposure: An Indicator of Heavy Metal Stress?

Changes in erythron organization were examined in goldfish (Carassius auratus) exposed for 3 wk to 5, 15, and 25% of 240-h Cd LC50. In a subsequent, more extended study, specimens were first rendered acutely anemic by immersion in phenylhydrazine HCl, allowed to recover in Cd-free water or in concentrations equivalent to ~5 or ~11% of LC50, and sampled after 2, 5, 8, and 11 wk. Total, dividing, and degrading or karyorrhectic cell numbers were recorded, as were cell length, one-sided surface area, and form factor, in fish exposed to ~11% LC50, total cell numbers and the incidence of cell division fell, while karyorrhexis increased. Dividing to total cell ratios declined with time; karyorrhectic to total and karyorrhectic to dividing cell ratios increased. Variations in cytomorphology suggested slower cell maturation at both metal concentrations. Detection of heavy metal stress in fishes by this form of hematological assessment appears feasible.