||Factors Influencing Mercury Concentrations in Walleyes in Northern Wisconsin Lakes.
Wiener, J. G. ;
Martini, R. E. ;
Sheffy, T. B. ;
Glass, G. E. ;
||National Fisheries Contaminant Research Center, La Crosse, WI. Field Research Station. ;Wisconsin Dept. of Natural Resources, Madison.;Environmental Research Lab.-Duluth, MN.
Water pollution effects(Animals) ;
Regression analysis ;
Body size ;
Biological availability ;
Walleye pike ;
Northern Region(Wisconsin) ;
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The study examined relations between mercury concentrations in walleyes Stizostedion vitreum and the characteristics of clear-water Wisconsin lakes, which spanned a broad range of pH values (5.0-8.1) and acid-neutralizing capacities (-9 to 1,017 microgram eq/L). Total concentrations of mercury in axial muscle tissue of walleyes (total length, 25-56 cm) varied from 0.12 to 1.74 microgram g/g wet weight. Concentrations were greatest in fish from the eight lakes with pH less than 7.0; concentrations in these fish equaled or exceeded 0.5 microgram g/g in 88% of the samples analyzed and 1.0 microgram g/g in 44%. In the five lakes with pH of 7.0 and above, concentrations exceeded 0.5 microgram g/g in only 1 of 21 walleyes. Multiple regression revealed that lake pH and total length of fish accounted for 69% of the variation in mercury concentration in walleyes. Regression models with total length and either waterborne calcium or acid-neutralizing capacity as independent variables accounted for 67% of the variation in concentration. The observed differences in fish mercury concentration between the low-pH and high-pH lakes could not be logically attributed to differences in growth rate or diet among the walleye populations. Moreover, it is improbable that mercury influxes to the low-pH lakes were greater than those to the high-pH lakes, because of the close proximity and spatial interspersion of low- and high-pH lakes.