The effect of high lead concentrations on the mortality, mass and behaviour of <i>Porcellio laevis</i> Latr. (Crustacea, Isopoda) in laboratory tests

Abstract

The aim of this study was to determine the effects of high lead concentrations on the terrestrial isopod Porcellio laevis and to determine whether these animals could distinguish between lead contaminated and uncontami-nated leaves. In the acute toxicity tests the isopods were exposed to 0, 15, 30,45, 60, 75, 90 and 105 g/kg lead nitrate. Behavioural tests were conducted exposing the isopods to 0, 15 and 105 g/kg lead nitrate. In the acute toxicity tests the various concentrations differed significantly concerning mortality and weight loss of surviving isopods. The LC₅₀ after 14 days exposure for P. laevis was 87.4 g/kg. The LC₅₀ values obtained in this study are extremely high compared to those of earthworms. This is an indication of high tolerance for lead. The concentrations of lead found in the isopods were high and could give a possible explanation for the mortalities and mass losses observed, as lead at those concentrations could have disturbed the normal physiological functioning of the animals. The isopods avoided lead contaminated leaves in the behavioural tests, which could cause accumulation of leaf litter and thus a reduction of the decomposition rate.