| The biological response of periphyton chronically exposed to metals of urban origin (Cd, Ni and Zn) was investigated with a Pollution-Induced Community Tolerance (PICT) approach using a previously developed short-term toxicity test based on beta-glucosidase (heterotrophic) activity. Periphyton was grown on plastic membranes immersed in indoor aquaria contaminated with metals at realistic contamination levels (0.3, 3 mu g/l for Cd, 5, 50 mu g/l for Ni, 20, 200 mu g/l for Zn). After 3 weeks of exposure, biofilms' parameters (dry-weight, chlorophyll a concentration, heterotrophic activity) were analyzed and tolerance acquisition of the heterotrophic communities was assessed using the toxicity test. Modifications of bacterial and eukaryotic community structure... |
