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Choosing the right organism for use in sediment avoidance behavior tests; how other behaviors affect this choice.
Citation:
Yeardley, R., J. Lazorchak, AND M. Mills. Choosing the right organism for use in sediment avoidance behavior tests; how other behaviors affect this choice. SETAC North America 44th Annual Meeting, Louisville, KY, November 12 - 16, 2023.
Impact/Purpose:
This research is in support of the need for fast, effective ecological screening tests for contaminated sites. Based upon previous success with earthworm avoidance testing (Yeardley et al 1996), U.S. EPA (Cincinnati, OH) will use soils/ sediments collected from multiple sites, including Great Lakes AOC sites, to develop macroinvertebrate sediment avoidance tests and explore the applicability of this method in assessing the remediation effects. This data and method coming from this research will be useful to inform a number of potential and remediation and restoration efforts at AOC, Superfund, and other sites. When fully developed, this fast, inexpensive test (along with guidance developed along with the test) can be used by communities without sufficient resources for expensive tests to assess water/ sediment quality, including tribes and citizen science groups.
Description:
Soil avoidance tests have been developed for earthworms, Collembola, and other soil organisms. Many organisms are sensitive to toxic contaminants and have the ability to avoid areas of contamination. Correlations between avoidance behavior and acute and other toxicities have been found by our lab and others. Earthworm soil avoidance tests have been increasingly used in risk assessment since their development circa 1996, until in 2008 an international standard method (ISO 17512-1) was published. So, the potential for a sediment avoidance test is there. We assessed the potential for use of the freshwater aquatic macroinvertebrates (Chironomus dilutus larvae, Hyalella azteca, and Lumbriculus variegatus) used in standard USEPA sediment toxicity and bioaccumulation methods (Methods 100.1, 100.2, and 100.3), for use in sediment avoidance testing. Behaviors other than avoidance of contaminants - feeding habits, predator avoidance, mating, phototaxis, thigmotaxis, and especially mobility - affect avoidance testing. So, we have been evaluating these candidate organisms with respect to these behaviors. Presence or absence of sediment affected phototactic behavior. With no sediment present, both Hyalella and Lumbriculus showed a preference for the dark sides of chambers. In tests with sediment present, Hyalella showed a preference for light, while Lumbriculus showed no preference. 24-hour mobility tests with reference sediment, with a null hypothesis that the organisms will not remain on the same half of the chamber where they were placed at test start, showed that Chironomus (p=0.002) did not exhibit sufficient mobility to be useful in avoidance testing. Hyalella (p=0.327) showed good mobility. Lumbriculus (p=0.236) fared better than Chironomus in these mobility tests, but Lumbriculus did not spread themselves relatively evenly in chambers with only reference sediment. Due to the ecological relevance of Lumbriculus and its habit of moving through the soil to feed, thus being in contact with sediment both internally and externally, we varied test parameters such as light/ dark and test duration to see if the right parameters could be found where the worms would clearly spread themselves evenly in chambers in absence of contaminated sediment. In addition to the results of phototaxis and mobility tests, we will present the results of tests with Lumbriculus where the light/dark conditions and test length were varied.
URLs/Downloads:
https://www.setac.org/discover-events/global-meetings/setac-north-america-44th-annual-meeting.html