Importance of contamination history for understanding toxicity of copper to earthworm Eisenia fetica (Oligochaeta : Annelida), using neutral-red retention assay

Eisenia fetida was exposed in the laboratory to a range of elevated soil co pper (Cu) concentrations under two different contamination histories. An EC 10 for reproduction was observed at 34 mg Cu/kg for soil spiked with Cu 1 d prior to running the experiment (newly spiked soil). Soil contaminated wit h Cu in the field more than 70 years previously (field-contaminated soil) c aused a 10% decrease in reproduction at 248 mg Cu/kg. Survival and cocoon w et weights were not affected by soil concentrations up to 1,400 mg Cu/kg un der either contamination history. Adult growth was reduced at 428 mg Cu/kg (EC10) in newly spiked soil but not in field-contaminated soil at concentra tions up to 1,400 mg Cu/kg. The contamination history, as well as the toxic ological parameter, was important in the interpretation of the outcome of a standard laboratory toxicity test. The lysosomal membrane stability of coe lomocytes, measured as neutral-red retention time (NRR-time), was reduced a t soil Cu concentrations lower than those affecting reproduction and demons trated a dose-response relationship. The NRR-time was more severely reduced in worms exposed to newly Cu-spiked soil (EC10 = 8 mg Cu/kg) than worms ex posed to field-contaminated soil (EC10 = 69 mg Cu/kg). The NRR-time reflect ed the bioactive Cu fraction, showing a good correlation with reproduction under both contamination histories.