The isopod Porcellio scaber as a monitor of the bioavailability of metals in terrestrial ecosystems: towards a global ‘woodlouse watch’ scheme

Abstract

Concentrations of cadmium, copper, lead and zinc were determined in nitric acid digests of the terrestrial isopods (woodlice) Porcellio scaber and Oniscus asellus, and soil collected from 48 sites in a region in S.W. England contaminated by earlier mining activity and ongoing aerial fallout from a smelting works. For all four metals, closer correlations were obtained between the two species of isopods than between soil and isopods. Thus, levels of metals in Oniscus asellus could be predicted more accurately from those in Porcellio scaber than from concentrations in soil in the region. A table is included that allows the ‘level of contamination’ of a site to be assessed based on concentrations of metals in a pooled sample of 12 adult Porcellio scaber. Preliminary correlations are also presented between Porcellio scaber, Oniscus asellus and nine other species of terrestrial isopods. The worldwide distribution of Porcellio scaber (which has been introduced to most countries) makes this woodlouse an ideal candidate for monitoring the bioavailability of metals to soil and leaf litter invertebrates. A global ‘woodhouse watch’ is proposed, similar to the ‘mussel watch’ scheme that has proved so successful in the marine environment.