PARENT SESSION
PM2 - Soil Toxicology
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P230) The predictive relationship between avoidance behaviour and reproductive effects in earthworms.

Stephenson, Gladys¹, Feisthauer, Natalie^*,1, Elshayeb, Monalisa², Scroggins, Richard³, ¹ ESG International, Inc., Guelph, Ontario, Canada² University of Guelph, Guelph, Ontario, Canada³ Environment Canada, Ottawa, Ontario, Canada

ABSTRACT- A test method for quantifying earthworm avoidance behaviour is under development as part of an initiative undertaken by Environment Canada to develop national terrestrial toxicity test methods for earthworms, arthropods, and plants. Avoidance tests and reproduction tests were conducted with one earthworm species, Eisenia andrei in a clay loam soil amended or contaminated with different compounds. The contaminants tested included copper sulphate, benomyl, amines, crude oil, and condensates. E. andrei reproduction tests were conducted for 56 to 70 days. Reproduction metrics included juvenile number, wet and dry juvenile mass, and number of hatched and unhatched cocoons. Avoidance behaviour tests were conducted for 24 and 72 hours, and the assessment endpoint was the non-random distribution of worms. Soils in both were amended (or serially diluted with clean soil in the case of amines and condensates) independently of each other at sublethal concentrations. The highest contaminant concentration at which E. andrei did not display a significant avoidance response ("avoidance threshold") was compared with the EC20s, or LOECs estimated for each reproduction endpoint. In every case tested, the highest soil concentration for each of the treatments that did not elicit an avoidance response in E. andrei was similar or lower than the EC20 or LOEC of the most sensitive reproductive endpoint. For example, the "avoidance thresholds" for E. andrei exposed to copper sulphate, benomyl, crude oil, amines, and condensates were 125 mg/kg, 13 mg/kg, < 0.5 mg/g, 1%, and 3%, respectively. This was compared to the EC20s or LOECs for the most sensitive reproductive metrics, which were 134 mg/kg, 19 mg/kg, 0.8 mg/g, 6%, and 6% for copper sulphate, benomyl, crude oil, amines, and condensates, respectively. These results imply that E. andrei actively avoided those levels of contamination that resulted in adverse reproductive effects, and that a one to three day avoidance response test has the potential to rapidly produce results which might be used to successfully predict the chronic toxicity of contaminated soils to earthworms.

Key words: earthworms, avoidance, reproduction, soils