The distribution of cadmium, copper, lead, zinc and calcium in the tissues of the earthworm Lumbricus rubellus sampled from one uncontaminated and four polluted soils

Abstract

The tissue distribution of Cu, Cd, Pb, Zn, and Ca in the earthworm Lumbricus rubellus living in non-polluted and heavy-metal polluted soils was investigated. Cd, Pb and Zn were primarily accumulated within the posterior alimentary canal. As the whole-worm Pb burden increased, the proportion of the metal accumulated within this tissue fraction increased. A similar pattern was found for Zn. By contrast, 70%-76% of the Cd burden was found in the posterior alimentary canal, irrespective of the whole-worm Cd content. The accumulation of Cd, Pb and Zn primarily in the posterior alimentary canal prevents dissemination of large concentrations of these metals into other earthworm tissues, and may thus represent a dextoxification strategy based on accumulative immobilisation. Cu was distributed fairly evenly in the tissue fractions investigated. There was no evidence of sequestration of this metal. The apparent lack of a detoxification strategy may contribute to the well-known susceptibility of earthworms to low environmental Cu concentrations. Indeed, earthworms from the site of highest soil Cu (Ecton) were markedly smaller than those from the other sites sampled. The highest Ca concentrations were found in the anterior alimentary canal, and were related to calciferous gland activity. A large proportion of Ca was also stored as a physiologically available pool in the posterior alimentary canal. Despite huge variations in soil Ca concentrations, the body wall Ca levels were fairly similar in L. rubellus from all the study sites. Thus, L. rubellus may become physiologically adapted to soils of exceptionally low Ca concentration. The observations are discussed in the context of the merits of analysing specific tissues, rather than whole organisms, for the purpose of monitoring metal bioaccumulation.

Relevance and Applicability of a Simple Earthworm Biomarker of Copper Exposure. I. Links to Ecological Effects in a Laboratory Study withEisenia andrei

“…Streit (1984) proposed a model for the uptake of copper by earthworms including active excretion, which was activated when a critical body concentration was exceeded, while Neuhauser et al (1985) suggested saturation of uptake sites or active regulation of assimilation, being in line with the possibility of a restricted uptake mechanism as proposed by Hopkin (1989). Whatever mechanism resulted in this pattern of lower BCFs of copper at higher soil concentrations, such evidence indicates that earthworms probably manage copper by active regulation, rather than adapt a strategy based on accumulative detoxification (Morgan and Morgan, 1990). Consideration of the relationship between individual earthworm tissue copper concentrations and their neutral-red retention times (i.e., the level of cellular stress) (Fig.…”

Effects of the Fungicide Copper Oxychloride on the Growth and Reproduction of Eisenia fetida (Oligochaeta)

“…The susceptibility of earthworms to copper may be the result of an inability of most tissues to synthesize Cubinding ligands in response to the presence of the metal. Earthworms most likely manage copper by regulation rather than by accumulative detoxi"cation (Morgan and Morgan, 1990).…”

Relevance and Applicability of a Simple Earthworm Biomarker of Copper Exposure. II. Validation and Applicability under Field Conditions in a Mesocosm Experiment withLumbricus rubellus

“…80, 160, and 320 mg Cu kg −1 ) was sufficiently elevated to cause the tissue copper concentrations of the earthworm to rise above this critical level, despite the activity of the earthworm regulatory mechanism (BCFs ca. 0.3) (Morgan and Morgan, 1990). The neutral-red retention time corresponding to this critical body copper concentration was calculated as 24, 32, and 24 min and the tissue copper concentration EC 50 for the neutral-red response was 25, 39, and 38 g SVENDSEN AND WEEKS be maintained below the critical level without the need for extensive regulation by the earthworm (BCF ca.…”