PHYSIOLOGICAL-CHANGES AND TISSUE METAL ACCUMULATION IN RAINBOW-TROUT EXPOSED TO FOODBORNE AND WATERBORNE METALS

Sublethal physiological effects and metal residue accumulation in tiss ues were measured in adult and juvenile rainbow trout fed a metal-cont aminated diet and/or exposed to waterborne metals for 21 d. The consum ption of metal-contaminated invertebrates from the Clark Fork River, M ontana, significantly affected scale loss and metal accumulation in gu t tissue of adult trout. Survival, scale loss, and metal accumulation in gill and kidney tissue were affected by exposure to a waterborne mi xture of Cd, Cu, and Pb at twice the acceptable levels and Zn at the m aximum acceptable level established by the U.S. Environmental Protecti on Agency for protection of aquatic wildlife. A combination of dietary and waterborne metals also caused lipid peroxidation in the kidney of adult fish and decreased whole-body potassium of juvenile trout. In g eneral, metal accumulation in tissues was higher in gill and kidney wi th waterborne exposures and was higher in stomach and pyloric caeca wi th dietary exposure. And metal concentrations in juvenile whole-body t issues accumulated significantly with a combination of waterborne and dietary metals. Although some;physiological changes were noted (scale loss, lipid peroxidation of kidney), an exposure time longer than 21 d is probably needed to observe more extensive physiological changes. R egardless, results from this study suggest that a full assessment of m etal exposure to fish populations in natural systems must include eval uation of dietary as well as waterborne metal contamination.