Autotomy as a mechanism of decontamination used by the oligochaete Tubifextubifex

Previous work suggested that the oligochaeta T. tubifex may tolerate the co ntamination of its environment by Cu and Pb by accumulating these metals in the caudal region and by subsequently autotomizing the latter. The aim of the present study was to investigate whether these phenomena may be observe d with other metals such as Cd, for example. Acute toxicity of Cd was estim ated by LC 50-96 h measurements and subacute toxicity by scanning electroni c microscope observations. Results indicated that Cd also induced autotomy of the posterior region of the worms. However, analysis conducted in the an terior and the posterior parts of the worms exposed to Cd concentration low er than those inducing autotomy did not show any antero-posterior gradient. Further work is thus necessary to improve the understanding of this latter observation.