Abstract

  In 1987, the Great Lakes Water Quality Agreement (GLWQA) committed the governments of Canada and the United States to develop plans and recommend specific actions for the restoration and recovery of degraded nearshore areas commonly called "Areas of Concern (AOCs)". The Great Lakes AOCs are defined as those areas that fail to meet the general or specific objectives of GLWQA, resulting in the impairment of biological use(s) or impairment of the areas' ability to support aquatic life.
  During the period 1991-92 field season, Fisheries and Oceans Canada conducted extensive field and laboratory work for the bioassessment of nine Lake Erie AOCs. With the exception of one, most of the rivers drain into Lake Erie: Buffalo, Ashtabula, Cuyahoga, Black, Maumee, Raisin, Rouge, Detroit and Wheatley Harbour.
The bioassessment consisted of both water and sediments. Multi-trophic acute assays were conducted using Daphnia magna, Hyalella azteca, Lumbriculus variegatus, Microtox and carbon-14 size fractionated primary production.
  The field and laboratory work generated an extensive database indicating a differential response of various trophic levels. While the tests were consistent in determining the most toxic hot spots, variability existed in the sensitivities of test organisms to discriminate among less contaminated sites. The multi-trophic battery of tests approach applied in our study appears to be effective in detecting and discriminating differential sensitivities of both water borne and sediment bound contaminants.