The effect of copper (44 microg l(-1)) on a simple food chain was studied using indoor experimental channels to identify the changes in periphyton community (metabolism, chlorophyll a content, abundance, composition and lipid and protein content) and in herbivore (Stagnicola vulnerata) growth rate and reproduction. The algal community was sensitive to copper at the beginning but differences between treatments were not significant during the experiment. However, copper affected growth rate, reproduction and embryo hatching on snails. These results indicate that the effects on snails are more sensitive endpoints in assessing sublethal copper toxicity than effects on periphyton.