PARENT SESSION
Poster Session #21: Education.
Wednesday, August 8, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

A laboratory exercise using a standardized soil ecotoxicological test.

Paradise, Christopher¹, ¹

ABSTRACT- I describe how a standardized USEPA assay to test effects of soil contaminants on red worms (Eisenia fetida) can be used as a laboratory exercise. The advantages of such assays are improved assessment of pollutant effects and the ability to compare effects across species or ecosystems. The test is simple, inexpensive, and adaptable to a variety of courses. Soils can contain complex mixtures of contaminants, and this assay tests the response of a single species. Potential contaminants include organic pesticides and heavy metal compounds, both common soil contaminants. Earthworms are a good choice for the test because they are ubiquitous in soils, and play a role in soil formation and nutrient cycling. Students learn how to design long-term experiments and determine lethal concentrations. They develop 28-day mortality vs. concentration curves, estimate LC₅₀ values, and test for impairment of growth and reproduction. Data may be collected weekly by having students come in on their own or just at the end of the test period. This exercise has application to courses such as ecology, zoology, and environmental science. Discussion points include effects of pollutants on organisms, the pros and cons of standardized microcosm tests, the importance of earthworms to soil ecosystems and humans, and the ecology and natural history of earthworms. Ecological concepts, such as population growth rates or the effects of abiotic factors on populations, may also be discussed.

KEY WORDS: ecotoxicology, Eisenia fetida, soil pollution, LC₅₀