Impact of cadmium and lead on Megaphyllum kievense (Diplopoda, Julidae) in a laboratory experiment

Abstract

After accumulating in plants, lead and cadmium of technogenic origin concentrate in forest litter, thus inhibiting the speed of its microbiological decomposition and causing chronic intoxication of saprophage millipedes which feed on it. The 20-day laboratory experiment described in this article determined the toxic impact of lead and cadmium (at concentrations of 0.3, 3, 30, 300, 3,000 and 30,000 mg/kg of litter) on the body weight of Megaphyllum kievense (Lohmander, 1928) and microbiological decomposition of forest litter. The death rate of M. kievense increased from 10–20% to 40% at 3 and 30 g/kg of lead and to 100% at 30 g of cadmium per 1 kg of litter. Gain in body weight of M. kievense reliably decreased only at 3 g/kg of cadmium (0.71 to 0.20 mg/24-hours). Under the influence of lead, gain in body weight reliably decreased compared to the control already at 100 times smaller concentration (30 mg/kg of substrate – 0.74 to 0.10 mg/24-hours). Under the influence of both cadmium and lead, the decomposition of litter by microorganisms is slowed down only under the highest of the studied concentrations (30 g/kg). The results of the laboratory experiment showed high resistance of M. kievense to lead and cadmium, at levels significantly higher than natural concentrations of heavy metals in technogenically transformed ecosystems.