Effect of traffic on survival and reproduction of enchytraeidEnchytraeus crypticus in soils near belt highways

The development of new roads and the increasing number of cars has led to a substantial input of persistent organic pollutants (POPs) and heavy metals into surrounding ecosystems. This affects the quality of the soils and they may become toxic for soil organisms including enchytraeids (Annelida, Oligochaeta). The aim of this study was to investigate the pollution of soil by polycyclic aromatic hydrocarbons (PAHs) and heavy metals along busy roads; and to consequently assess the effects on Enchytraeus crypticus survival and reproduction in these soils. The chosen sampling sites were situated at either the roadside or 10 to 20 m from the roadside of two belt highways in Prague, Czech Republic. These sites were compared each other and with similar control sites in the area of the expected future direction of highways, but without any traffic impact so far. Physico to chemical properties and soil contamination were measured and the soils were tested for toxicity to E. crypticus survival and reproduction according to standardized OECD enchytraeid test. Traffic clearly influenced the PAHs concentrations in soil; but no relationship was found with heavy metal loads. Results of toxicity tests with E. crypticus did not indicate a clear relationship to soil contaminations. Similar results were found with soils from roadsides and remote sites. Enchytraeid survival and reproduction were apparently determined by physical to chemical properties of the test soils which obscured contamination toxicity relationships. In particular low pH values caused negative effects on the enchytraeids.