Description of Work This study will generate bed sediment toxicity and benthic community data needed to test two related hypotheses that address the two criteria for delisting the benthos BUI. The first hypothesis is that bed sediments at selected sample locations in the AOC (in three tributaries and in the St. Lawrence River) are no more toxic to the test species than bed sediments collected from control sites located outside (generally upstream from) the AOC. Acute (survival) and chronic (growth) whole bed-sediment toxicity tests will be conducted using the midge (Chironomus dilutus), following standard methods (USEPA 1994; USEPA 2000). The second hypothesis is that the benthic macroinvertebrate communities from targeted sites within [...]
