COMPARISON OF THE RELATIVE SENSITIVITY OF 3 BENTHIC INVERTEBRATES TO COPPER-CONTAMINATED SEDIMENTS FROM THE KEWEENAW WATERWAY

The Keweenaw Peninsula in northern Michigan was once a major copper mi ning area and these mining activities were responsible for depositing tons of tailings in and around the Keweenaw Waterway. In recent years there has been concern about possible toxic effects of the contaminate d sediments on aquatic communities in the system. In the fall of 1990, sediments were collected from various locations along the Waterway. T en-day tests were conducted with the samples using three species of be nthic invertebrates that have been proposed as suitable for evaluating the toxicity of freshwater sediments: Hyalella azteca (amphipods), Ch ironomus tentans (chironomids) and Lumbriculus variegatus (oligochaete s). A number of sediments were toxic to one or more of the three speci es and, in general, there was good agreement among the tests with rega rd to identifying toxic samples. Unexpectedly, the relative sensitivit y of the three species to the test sediments was not accurately predic ted from water-only copper exposures. This indicates that factors modi fying exposure, such as different lifestyles and/or varying sensitivit y to physico-chemical characteristics of sediments can influence resul ts of sediment toxicity tests.