Response of plasma cortisol to environmental cadmium in the eel, Anguilla rostrata LeSueur.

1. Long-term exposure (16 weeks) of the American eel, Anguilla rostrata, to an environmentally realistic concentration of cadmium (150 micrograms/l) causes a chronic elevation of plasma cortisol. During this time span, the eels retain the ability to respond to a weak additional stress (CO2 bubbles for 1 min) with a further increase in plasma cortisol. 2. Plasma glucose levels are significantly lowered after two weeks of exposure to cadmium (75 and 150 micrograms/l). However, subsequently they return close to control levels. 3. It is concluded that (a) a moderate cadmium pollution of the eel's habitat suffices to cause chronic stimulation of the eel's adrenocortical axis, and (b) the resulting continued hypercortisolemia must seriously affect the eel's metabolism, immunosystem, gonadal maturation, and ability to migrate to its spawning grounds.