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(70-83) Effects of whole-lake acidification on bioaccumulation of cadmium in yellow perch (Perca flavescens) populations. Powell, David*,1,2, Rada, Ronald2, Wiener, James2, Atchison, Gary3, 1 Environmental Sciences, Midland, Michigan, USA2 River Studies Center, La Crosse, Wisconsin, USA3 Department of Animal Ecology, Ames, Iowa, USA ABSTRACT- The bioaccumulation of cadmium by yellow perch (Perca flavescens) in relation to the process of whole-lake acidification was studied in Little Rock Lake, the site of an experimental pH manipulation project. Little Rock Lake was separated with an impermeable curtain into a reference basin (mean pH 6.1) and treatment basin that was acidified with sulfuric acid for two years to pH 5.6, two years to pH 5.2, and two years to pH 4.9. Age-1 yellow perch used for cadmium analyses were annually netted from each basin in April, after one year of residence in the lake, during the two years of the pH-5.2 treatment and during the two years of the pH-4.9 treatment. Older yellow perch, representing all total-length groups, were sampled after completion of the pH-5.2 treatment and after completion of the pH-4.9 treatment. Mean whole-body concentrations of cadmium in age-1 yellow perch were greater in reference-basin fish than in treatment-basin fish after each year of the pH-4.9 treatment, but did not differ between basins during the pH-5.2 treatments. Similarly, mean whole-body burdens (i.e. mass) of cadmium bioaccumulated by age-1 yellow perch were greater in the reference basin than the treatment basin during the pH-4.9 treatments, but did not differ between basins during the pH-5.2 treatments. Mean whole-body cadmium concentrations and burdens in the perch populations were greater in the reference basin than the treatment basin for fish age-2 and older and for fish from total-length groups larger than 130 mm. Bioaccumulation of cadmium in fish collected from the two basins of Little Rock Lake after the pH-5.2 and the pH-4.9 treatments paralleled age and rates of growth within the yellow perch populations, with the relationship being strongest for reference-basin fish. The estimated inventory of cadmium in the yellow perch populations in Little Rock Lake, based on analyses of samples collected after the pH-5.2 treatment, was 24.1 mg in the 8-hectare reference basin and 18.8 mg in the 10-hectare treatment basin. Key words: cadmium, fish, bioaccumulation, acidification |
