ASSESSING CONTAMINATION IN GREAT-LAKES SEDIMENTS USING BENTHIC INVERTEBRATE COMMUNITIES AND THE SEDIMENT QUALITY TRIAD APPROACH

Sediments in many Great Lakes harbors and tributary rivers are contami nated. As part of the USEPA's Assessment and Remediation of Contaminat ed Sediment (ARCS) program, a number of studies were conducted to dete rmine the nature and extent of sediment contamination in Great Lakes A reas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a se ries of papers describing studies conducted to evaluate sediment toxic ity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw R iver, MI), as part of the ARCS Program. Oligochaeta (worms) and Chiron omidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consiste d of taxa identified as primarily contaminant tolerant organisms. Stru ctural deformities of mouthparts in midge larvae were pronounced in ma ny of the samples. Goad concurrence was evident between measures of la boratory toxicity, sediment contaminant concentration, and benthic inv ertebrate community composition in extremely contaminated samples. How ever in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxic ity test results or sediment contaminant concentration. Laboratory sed iment toxicity tests may better identify chemical contamination in sed iments than many commonly used measures of benthic invertebrate commun ity composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are neede d to better interpret the response of benthic invertebrates to sedimen t contamination.