Response types in Collembola towards copper in the microenvironment

Laboratory studies were carried out to cast light on differences in density responses among collembolan species to copper (Cu)-polluted environments. In a recolonisation experiment, mesofauna originating from a copper (Cupoll uted arable field were allowed to colonise defaunated Cu-contaminated and u ncontaminated soil cores for 3 months. The abundances of Pseudosinella alba and gamasid mites were higher in the uncontaminated soil, whereas the majo rity of other collembolans tended to be more abundant in the Cu-enriched so il. Behavioural experiments were conducted to test the ability of single Co llembola species to distinguish between filter paper and food soaked in wat er, Cu, and calcium (Ca) solutions. Onychiurus armatus avoided both Cu and Ca, whereas Folsomia quadrioculata and Folsomia manolachei showed a signifi cant preference for Cu. Isotomurus palustris was not able to distinguish be tween Cu and water. The results are compared and discussed with regard to o ther studies on the occurrence and behaviour of Collembola in Cu-contaminat ed environments. We suggest that microsite selection according to preferenc e or avoidance of high salinity of pore water may partly explain the commun ity structure of Collembola in Cu-polluted soils which are characterised by an increase of euedaphic species. More studies have to be carried out to g eneralise this concept and to explore to what extent reduced predation by g amasid mites contribute to the success of certain Collembola in Cu-contamin ated sites. (C) 1999 Elsevier Science Ltd. All rights reserved.