Biochemical changes in longear sunfish, Lepomis megalotis, associated with lead, cadmium and zinc from mine tailings

Longear sunfish were collected from a stream contaminated with mine tailings rich in lead (Pb), cadmium (Cd) and zinc (Zn). Blood samples were analysed for δ-aminolevulinic acid dehydratase (ALA-D) activity and Pb concentration. Vertebrae were tested for bone strength and composition, and Pb, Zn, and Cd concentrations were determined in muscle tissue. ALA-D activity was negatively correlated with blood Pb concentration (r=–0.66), and enzyme activity was significantly higher and blood Pb significantly lower at the reference site than at the contaminated sites. Blood Pb was highly correlated with Pb in muscle tissue (r= 0.72), and the concentrations of Pb and Cd in muscle tissues were themselves correlated (r= 0.64). In fish from contaminated sites, two of the mechanical properties of the vertebrae measured (elastic limit and modulus of elasticity) were significantly different from values in fish from the reference site. These properties and one other (stress) were weakly correlated with muscle Cd concentration (0.42