The bioavailability of metals can be influenced not only by soil properties but also by other species living at polluted sites. However, in laboratory experiments, usually only one test species is used to estimate bioavailability. In this study, a two-species approach was applied to assess the impact of the earthworm Lumbricus rubellus on the bioavailability of cadmium and lead to the springtail Folsomia candida using natural soils from a gradient of metal pollution. Earthworms were kept in half of the soil replicates for 4 weeks. Subsequently, the uptake and elimination kinetics of cadmium and lead in F. candida exposed for 21 days to the soils was determined. Earthworm activity affected soil properties but did not significantly affect metal uptake rate constants in springtails. The slightly higher uptake due to the presence of earthworms, which was consistent in all tested soils and for both metals, suggests that further research is needed on the role of species interactions in affecting metal bioavailability in soil.

CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos InBIO Laboratório Associado Universidade do Porto 4485 661 Vairão Portugal

Department of Ecological Science Faculty of Science Vrije Universiteit De Boelelaan 1085 1081 HV Amsterdam The Netherlands

Institute for Environmental Studies Charles University Prague Benátská 2 CZ 12801 Prague Czech Republic Institute of Soil Biology and SoWa Research Infrastructure Biology Centre Czech Academy of Sciences Na Sádkách 7 CZ 37005 České Budějovice Czech Republic

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