Changes in the body mass of Megaphyllum kievense (Diplopoda, Julidae) and the granulometric composition of leaf litter subject to different concentrations of copper

摘要

This article discusses the results of a 30-day experiment investigating the influence of copper which was introduced into the natural diet of Megaphyllum kievense (Lohmander, 1928) at concentrations of 10^–1, 10^–2, 10^–3, 10^–4, 10^–5, 10^–6, 10^–7 and 10^–8 mg Cu·g^–1 dry leaf litter upon the body mass of the species. With copper contamination at a concentration 10^–1 mg Cu·g^–1 leaf litter the gain in body mass of M. kievense decreased by 69.8% (from 2.45 ± 1.28 to 0.74 ± 1.73 mg/individual per month). With an enrichment of the food substrate to 10^–2–10^–7 mg Cu·g^–1 litter the increase in body mass of the millipedes did not differ from the control value (it was 88–146% of the control). However, the gain in body mass for 10^–8 mg Cu·g^–1 dry leaf litter was twice higher than in the control. The results of the experiment do not permit us to claim that the food consumption of M. kievense changed in response to varying concentrations of copper in the litter samples. The mass of the largest litter fragments (> 2.05 mm) decreased by 8.5% as a result of consumption by M. kievense and that of the average size fragments (0.70–1.05 mm) increased by 6.0% due to the grinding of the plant remains by M. kievense and enrichment through their excretory process.