Trace metal concentrations in common carp (Cyprinus carpio) and walleyes (Stizostedion vitreum vitreum) in the Upper Wisconsin River
Littlejohn, Susan K.
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Mercury contamination has been a historical problem in the Upper Wisconsin River and was presumably caused by the use of phenyl mercuric acetate as a slimicide by the pulp and paper industry. Elevated levels of other n~tals in bed sediments have also been observed. Common carp and walleyes were collected from five sites in the main study area of the Upper Wisconsin River extending from the Brokaw area to the Lake DuBay Dam. Walleyes collected from the Rainbow Flowage and common carp from Range Line Lake, two relatively uncontaminated sites in northcentral Wisconsin, were used as reference samples. Four metals were analyzed, each in a selected tissue of the two species: zinc in gill filaments, cadmium and lead in liver, and mercury in axial muscle. Concentrations of mercury in common carp from the main study area were significantly higher than those in carp from the reference site. However, mercury levels in walleyes from the main study area were similar to those in walleyes from the reference site, Rainbow Flowage. Mercury concentrations in axial muscle of both species were similar to mercury levels in fish of similar size, analyzed during 1970-1973 from the same reaches of the Upper Wisconsin River. Mercury availability and cycling through biota of this system may be enhanced by rapid rates of methylation in surficial sediments, even though the most heavily contaminated sediments have been buried by subsequent deposits. In general. cadmium and lead concentrations in liver and zinc concentrations in gill filaments were not elevated in fish from the main study area, relative to values in reference samples.
Metals -- Environmental aspects
Wisconsin River (Wis.)
Water -- Pollution -- Wisconsin -- Wisconsin River