In situ bioassay chamber for assessment of sediment toxicity and bioaccumulation using benthic invertebrates

An in situ bioassay system for use in assessing sediment toxicity and bioaccumulation using benthic macroinvertebrates was developed and evaluated. A schematic of the testing apparatus is provided. The test chamber was evaluated by assessing growth and survival of the midge Chironomus tentans in several contaminated, reference, and control sediments, as well as by estimating bioaccumulation using the oligochaete Lumbriculus variegatus. The in situ exposure chamber tests were conducted at Hog Island, WI, and adjacent to the outfall of an abandoned steel plant in Duluth, MN. Results showed that the system provided an excellent assessment of toxicity under field conditions.