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Title: Evaluation of potential confounding factors in sediment toxicity tests with three freshwater benthic invertebrates

Journal Article · · Environmental Toxicology and Chemistry; (United States)
;  [1];  [2]; ;  [3];  [4]
  1. Environmental Protection Agency, Duluth, MN (United States)
  2. Spectrum Research, Inc., Duluth, MN (United States)
  3. National Water Research Inst., Burlington, Ontario (Canada)
  4. Science Applications International Corp., Hackensack, NJ (United States)

The authors examined the effects of natural sediment physicochemical properties on the results of lab tests with the amphipod Hyalella azteca, the midge Chironomus tentans, and the oligochaete Lumbriculus variegatus. Ten-day exposures with the three species were conducted with 50 uncontaminated sediment samples from Lakes Erie, Huron, Superior, and Ontario, which differed markedly with regard to characteristics such as grain-size distribution, organic carbon content, and mineralogical composition. Tests were conducted both with and without the addition of exogenous food. Survival of Hyalella azteca, survival and growth of Chironomus tentans, and survival/reproduction and growth of Lumbriculus variegatus were significantly greater in tests in which the animals were fed vs, those in which they were not. Approximately 10% of the tests in which Hyalella azteca was not fed and 80% of tests in which the amphipods were fed resulted in >80% survival, a common criterion for defining the acceptability of tests with Hyalella azteca in clean control sediments. Similarly, a relatively high percentage of the tests in which Chironomus tentans was not fed would have failed a control survival criterion of 70% for the midge. Hence, there is significant potential for false positive results if Hyalella azteca or Chironomus tentans is not fed during sediment tests. Predictive modeling of the assay results in relationship to sediment physicochemical characteristics failed to reveal any additional factors that influenced survival of Hyalella azteca and Chrionomus tentans, or reproduction and growth of Lumbriculus variegatus in tests in which the organisms were fed. However, linear modeling did suggest that growth of fed as well as unfed Chironomus tentans may have been influenced by grain-size distribution of the test sediments.

OSTI ID:
7066306
Journal Information:
Environmental Toxicology and Chemistry; (United States), Vol. 13:4; ISSN 0730-7268
Country of Publication:
United States
Language:
English