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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6183

Tuomas Lukkari, Marjo Aatsinki, Ari Vaisanen, and Jari Haimi; Toxicity of copper and zinc assessed with three different earthworm tests. Applied Soil Ecology 30:133-146, 2005

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At present, standardised earthworm acute toxicity and reproduction tests are used to assess the toxicity of heavy metal contaminated soils. These tests are, however, time-consuming, laborious and costly, and in addition, some sublethal responses may remain overlooked. Avoidance of metal contaminated soils by earthworms may be a useful parameter when assessing ecological risks with a low test effort. The objective of the present study was to find out whether the earthworm Aporrectodea tuberculata avoids soil simultaneously contaminated with Cu and Zn, and whether earlier exposure to metal-polluted soil affects its avoidance response. The aim was also to compare the sensitivity of the earthworm avoidance test to the standardised acute toxicity and reproduction tests. A. tuberculata clearly avoided lower soil metal concentrations than those that induced responses in the acute toxicity and reproduction tests. The standard species in the earthworm tests, Eisenia fetida, appeared to be more tolerant to metals and it seemed to regulate the tissue metal concentrations more strictly than A. tuberculata. The majority of the test parameters measured for A. tuberculata showed that earthworms of the population with long-term exposure history in metal-polluted soil responded at higher soil metal concentrations than earthworms of the population without earlier exposure to metal-polluted soil. Thus, the earthworms living in the metal contaminated area were either better adapted or acclimatized to live in metal contaminated soil. It was concluded that an earthworm test battery including avoidance, acute toxicity and reproduction tests can be an efficient tool in assessing ecological risks of contaminated soils. However, careful choise of the test species and even populations within the species is recommended.