Resistance to arsenic-toxicity in a population of the earthworm Lumbricus rubellus

Specimens of the earthworms Lumbricus terrestris L. and L. rubellus Hoffmeister from an uncontaminated site rapidly deteriorated in condition when kept in spoil rich in metal contaminants and arsenic. The site from which the spoil was collected supports several earthworm species, L. rubellus being dominant. Native L. rubellus survived for 12 weeks in spoil in the laboratory. L. rubellus collected from the spoil site and an uncontaminated site were kept for 28 d in uncontaminated soil and in soil containing 2000 mg sodium arsenate heptahydrate kg−1, the state of the specimens being recorded using a semi-quantitative assessment of earthworm condition (condition index, CI). The CI remained high for all specimens except those from the uncontaminated site kept in As-rich soil, for which mortality was 100% after 28 d. Tissue As concentrations in L rubellus from uncontaminated and contaminated sites were <1 mg kg−1 and 230 mg kg−1, respectively. In L. rubellus collected from the uncontaminated site and exposed to contaminated soil containing 2000 mg sodium arsenate heptahydrate kg−1, mean tissue As concentration was 92 mg kg−1.