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Evaluation of how multiple behaviors of standard U.S. EPA ecotoxicity test organisms affect their suitability for use in a sediment avoidance test.
Citation:
Yeardley, R., Jim Lazorchak, AND M. Mills. Evaluation of how multiple behaviors of standard U.S. EPA ecotoxicity test organisms affect their suitability for use in a sediment avoidance test. 2021 SETAC North America Annual Meeting, Virtual, November 14 - 18, 2021.
Impact/Purpose:
Avoidance of contaminated sediments by aquatic macroinvertebrates has the potential to provide a fast, sensitive, low-cost means of assessing risk from contamination and for evaluating the success of sediment remediation efforts at a range of contaminated sites (Superfund, Great Lakes Areas of Concern (AOC), mining).
Description:
Avoidance tests have been developed for earthworms, Collembola, and other soil organisms, based on the fact that these organisms are sensitive to many toxic contaminants and have the ability to avoid areas of contamination. Versions of an earthworm avoidance test have been increasingly used in risk assessment since its development in 1996. Avoidance testing with sediment organisms have less of a history of development and use, but this behavioral endpoint has similar potential as an indicator of population level effects, for use in decision-making, and for incorporation into regulatory assessments of chemical contaminants. We assessed the potential for use of the freshwater aquatic macroinvertebrates (Chironomus dilutus larvae, Hyallela azteca, and Lumbriculus variegatus) used in standard EPA sediment toxicity and bioaccumulation methods (EPA Methods 100.1, 100.2, and 100.3), for use in sediment avoidance testing. Previous testing with soils from contaminated sites has provided evidence that avoidance tests have the potential for increased sensitivity to contaminated sediments relative to standard toxicity tests for some of these test organisms. A current focus of testing is how other behaviors than avoidance of contaminants (feeding habits, predator avoidance, mating, phototactic responses to light), especially mobility, affect avoidance testing. These additional behaviors should be taken into account in developing test procedures, interpreting results, and most critically in choosing suitable test organisms. Mobility tests with reference sediment, with a null hypothesis that the organisms will spread themselves relatively evenly in chambers, showed differences in mobility between the organisms. In 24-hour tests Lumbriculus (p= 0.236) and Hyallela (p=0.327) both showed good mobility, whereas Chironomus (p=0.002) did not. We also discuss development of test procedures that can help prevent other behaviors (e.g. phototaxis, forming of colonies (Lumbriculus), pairing (Hyallela)) from significantly affecting test results.
