The distribution of zinc, cadmium, lead and copper within the woodlouse Oniscus asellus (Crustacea, Isopoda).

The concentrations of zinc, cadmium, lead and copper have been determined in the hepatopancreas, hindgut and rest of the body tissues of Oniscus asellus collected from eight sites in the U.K. The hepatopancreas is by far the most important storage organ of heavy metals, particularly cadmium, and at each site, contains a mean of at least 89% of the total body load of this element. Specimens of Oniscus asellus from contaminated sites may contain concentrations of zinc, cadmium, lead and copper in the hepatopancreas of about 1%, 0.5%, 2.5% and 3% of the dry weight respectively, which are among the highest so far recorded in the soft tissues of any animal.There is a significant positive correlation between the mean relative dry weight of the hepatopancreas of Oniscus asellus and the concentrations of zinc or cadmium in leaf litter from all eight sites. It is suggested that animals from sites which are contaminated heavily with zinc or cadmium have a large hepatopancreas because this enables them to 'de-toxify' a greater amount of the metal.