DAVID J. SOUCEK AND GAYLE P. NOBLET, 132 Long Hall, Clemson University, Clemson, South Carolina 29634, USA

A laboratory study was conducted to investigate the effect of copper contamination on recruitment of the endoparasitic Posthodiplostomum minimum (white grub) by bluegill Lepomis macrochirus. White grubs as encysted metacercariae have been reported from a number of fish species and are commonly found in the viscera of bluegill and other centrarchids. The life-cycle of this strigeid trematode was established in the laboratory using chicks as experimental definitive hosts and physid snails as first intermediate host. Upon completion of development in snails, juveniles emerged as free-swimming cercariae which then served as a source of infection for bluegill. The 96-hr LC50 of copper (a common algicide) for bluegill was determined to be 1.08 ppm (nominal concentration) under laboratory conditions. Sublethal copper concentrations used in parasite exposure experiments were 5, 10, and 20% of the LC50 value. Uninfected fish were exposed to sublethal concentrations of copper for two weeks, prior to exposure to cercariae. Percent mortality and parasite intensity was determined for fish in each concentration and compared to that of controls not exposed to copper. The potential for use of white grubs as bioindicators of pollution was assessed.