Pontoporeia Distribution Along the Keweenaw Shore of Lake Superior Affected by Copper Tailings

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The sediment and benthic macroinvertebrates of a 540 km2 area of Lake Superior were examined. The amphipod Pontoporeia hoyi was by far the most abundant animal collected. A 42 km2 area devoid of P. hoyi was found near where 50 million tons of copper tailings containing metallic copper in concentrations averaging 3750 mg/kg had been dumped between 1895 and 1968. In the no-amphipod region sediment copper ranged from 395 to 1310 mg/kg, while elsewhere mean levels were 14 to 298 mg/kg. The study area was divided into five transects which had maximum densities of P. hoyi ranging from 470 to 4480/m2. The depth of maximum density ranged from 40-45 to 60-65 m. Maximum density was associated with a mean grain size of φ 3.5-4.0 and elevated levels of total volatile solids, nitrogen, phosphorus, and chemical oxygen demand. Copper and dark color, characteristics of the copper tailings, showed significant negative correlations with P. hoyi density. © 1979, International Association for Great Lakes Research. All rights reserved.

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Journal of Great Lakes Research