THE ERADICATION OF AN EARTHWORM GENUS BY HEAVY-METALS IN SOUTHERN FRANCE

During the course of a broad study of polluted and non-polluted soils in southeastern France, we noticed that in contrast to other earthworms, the genus Scherotheca was only present in certain soils. Given the omnipresence of these invertebrates in the economy of nature, notably serving as food for a great number of birds and mammals, contributing to soil fertility, and maintaining high levels of water infiltration (thus reducing surface erosion in various soil profiles), we sought to determine what was responsible for the unusual absence of these animals in certain parts of our study area. For this purpose, we tested alternative hypotheses dealing with biogeographic, pedological and climatic factors before coming to the conclusion that it was a result of heavy metal contamination. We then proceeded to test all the potentially toxic heavy metals present in the soil in order to determine which one was responsible for the absence of Scherotheca. The results show that Scherotheca is highly susceptible to lead and copper.