THE INFLUENCE OF HEAVY-METALS ON THE GROWTH AND REPRODUCTION OF THE COMPOST WORM EISENIA-FETIDA (OLIGOCHAETA)

Earthworms of the species Eisenia fetida were exposed to metal salts o f cadmium, manganese, copper, lead and zinc to determine the effects o f heavy metals on growth and reproduction. Since ultrastructural damag e of spermatozoa was obtained after exposing the worms to heavy metals , the aim was also to relate this phenomenon to reproductive performan ce. The results showed that E. fetida responded differently to differe nt heavy metals. The concentration ratio for cadmium was the highest a nd worm growth and reproduction were severely affected. The worms grew well in the lead contaminated environment and produced cocoons at the same rate as the control worms. The hatchability of these cocoons wer e, however, much lower. This phenomenon corresponded the with occurren ce of extensive ultrastructural spermatozoon abnormalities, especially of the acrosome region, providing some indication that lead toxicity affects reproductive performance at this level. Worms exposed to zinc, manganese and copper grew slower than control worms, matured later an d produced fewer or no cocoons. The hatching success of the coccons pr oduced in the zinc contaminated substrate was not as severely affected as those from the lead exposure.