Dynamics of accumulation and decontamination of cadmium and zinc in carnivorous invertebrates. 2. The centipede Lithobius mutabilis Koch.

Abstract

Metals, being non-degradable, tend to accumulate in animals and hence long-term exposure even to low concentrations of metals may lead to harmful effects. From the physiological point of view, invertebrates may avoid metal poisoning either by retaining metals in inactivate forms, intracellular compartmentalisation or by discharging assimilated metals (Hopkin, 1989). Animals which represent the first strategy are able to concentrate elevated amounts of metals and are regarded as "macroconcentrators" (Dallinger, 1993). The second strategy is exhibited by animals possessing low concentrations of heavy metals, and these are termed “deconcentrators”. Consequently, numerous authors have reported that soil invertebrates belonging to the same trophic level exposed to the same environmental concentrations of metals often display different internal concentrations of metals and strategies for decontamination (e.g., Van Straalen and Van Wensem, 1986; Grodziska et al., 1987; Laskowski and Maryanski, 1993). In the trophic level containing predators, “macroconcentrators” are represented by spiders, “deconcentrators” by carabid beetles, whilst centipedes are regarded as being intermediate between these two extremes. Thus, an investigation comparing these three taxonomic groups in terms of kinetics of metals would be especially interesting. In the previous paper I have investigated the accumulation and decontamination dynamics of Zn and Cd in a carabid beetle Poecilus cupreus L. and showed that carabids exposed to elevated concentrations of Zn in food were able to maintain internal Zn concentrations at a constant level (Kramarz 1999). Although Cd concentrations increased in beetles fed Cd-contaminated food, its excess was quickly and efficiently excreted when switched to uncontaminated food. Additionally, zinc and cadmium did not affect each others uptake by P. cupreus (Kramarz, 1999). In this paper I report the results of the experiment on kinetics of the same metals, Zn and Cd in a centipede Lithobius mutabilis Koch.