Toxicity of copper to Porcellio scaber Latr (Isopoda) under different nutritional status

Isopods are members of the soil fauna important in decomposition. Their role in the decomposition of leaf litter in forest soils has been reported for many years (Gere 1956; Griffiths et al. 1989). Isopods are reported to contain high concentrations of copper in their haemolymph (70 mg/ml) and in hepatopancreas (216 mg/g d.w.) (Gunnarson and Hedlund 1987). The role that copper plays in the physiology and ecology of terrestrial isopods was first examined in detail by Wieser (1966, 1968), Dallinger (1977) and Dallinger and Wieser (1977). Furthermore, Wieser (1966, 1968) and Wieser et al. (1976) showed that copper concentrations of terrestrial isopods reflect the degree of environmental soil and litter contamination. In the last decade, pollution of the environment with heavy metals has led many environmental scientists to search for suitable methods to monitor distribution and effects of such pollution. Laboratory tests using terrestrial isopods are recommended for assessing the ecotoxicological effects of chemicals (Drobne and Hopkin 1994). Isopods are able to accumulate large amounts of several metals in their hepatopancreas (Hopkin 1989, 1990) therefore they are useful biological indicators of metal pollution (Dallinger et al. 1992). Because of its worldwide distribution and the high metal accumulation capacity, Hopkin et al. (1993) proposed that Porcellio scaber could be a suitable ''bioindicator'' of metal contaminated soils. In spite of the fact that copper is an essential metal in isopods, it may become toxic if it Is highly concentrated in the environment (Dallinger 1977; Dallinger and Wieser 1977), or released from the degraded haemocyanin (Gunnarson and Hedlund 1987) during a long period of starvation. The accumulation, metabolism, storage, detoxication and excretion of copper in isopods have been examined previously (Hopkin 1989). However, detailed information on the sublethal effects of copper in isopods and the influence of the nutritional status on the copper toxicity are sparse. In this paper we describe the effects of high concentrations of copper on consumption, growth rates and on reproduction correlates (gravids/females, offsping/females) applied in different foods to Porcellio scaber using a standard laboratory method.