Copper pharmacokinetics in fish gills—II body size relationships for accumulation and tolerance

In water contaminated with copper, juvenile and adult sunfish were found to accumulate copper in their gills. The time-course of accumulation was characterized by: (a) an initial fast, and (b) a subsequent slow phase. Biphasic kinetics were attributed to metabolic alterations associated with the toxicant's presence. The accumulation rate during the slow phase was determined to be 8.2 x 10⁻³ μg Cu(g fish)⁻¹ h⁻¹ for sunfish weighing 3.3 g, and values decreased disproportionately with body weight. Once the fish were transferred to uncontaminated water, copper was rapidly eliminated from the gills. Clearance was monophasic: the instantaneous clearance rate being a function of the copper concentration in the gills at a given time. The biological half-time was determined to be 1.6 h for fish weighing 3.5 g, and clearance rate constants decreased disproportionately with increasing body weight. It is proposed that clearance may be associated with the repair of gill ultrastructural damage and the rapid recovery from copper intoxication.