Metal content, after exposure to cadmium, of two species of earthworms of known differing calcium metabolic activity

Abstract

Exposure of Lumbricus rubellus and Allolobophora caliginos to 5 ppm cadmium chloride solution for 26 days resulted in accumulation of the metal, but this did not affect the concentrations of iron, zinc, manganese and copper. The naturally occurring difference in calcium concentrations between the species ( L. rubellus > A. caliginosa) also remained unchanged in cadmium-treated earthworms, indicating no cadmium/calcium relationship in either species. The post-clitellar region showed high concentrations of cadmium in the intestinal tissue but this could not be located ultrastructurally. Within the chloragocyte tissue, 70% of the cadmium was in the cell supernatant fraction and only 30% associated with the chloragosomes. An ultrastructural study, using both the conventional glutaraldehyde and the pyroantimonate fixation techniques, showed electron dense deposits within the debris vesicles of the chloragocyte cytoplasm. A technique to distinguish between surface-associated and internalised cadmium in the posterior body wall tissue showed that 68% of the metal of this tissue in L. rubellus was associated with the surface mucus.