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

The aim of this study was to determine the effects of high lead concentrati ons on the terrestrial isopod Porcellio laevis and to determine whether the se animals could distinguish between lead contaminated and uncontaminated l eaves. In the acute toxicity tests the isopods were exposed to 0, 15, 301 4 5, 60, 75, 90 and 105 g/kg lead nitrate. Behavioural tests were conducted e xposing the isopods to 0, 15 and 105 g/kg lead nitrate. In the acute toxici ty tests the various concentrations differed significantly concerning morta lity 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 ext remely high compared to those of earthworms. This is an indication of high tolerance for lead. The concentrations of lead found in the isopods were hi gh and could give a possible explanation for the mortalities and mass losse s observed, as lead at those concentrations could have disturbed the normal physiological functioning of the animals. The isopods avoided lead contami nated leaves in the behavioural tests, which could cause accumulation of le af litter and thus a reduction of the decomposition rate.