COMPARATIVE INVESTIGATION ON THE EFFECT OF A HERBICIDE ON AQUATIC ORGANISMS IN SINGLE-SPECIES TESTS AND AQUATIC MICROCOSMS

In the present investigation the effect of the herbicide isoproturon o n freshwater and sediment organisms was comparatively investigated in single species tests and a microcosm study. In single species tests th e photosynthesis inhibitor isoproturon affected the growth rate of alg ae. For Chlamydomonas rheinardi the EC50, i.e. the concentration, wher e the growth rate is inhibited to 50%, was observed at 40 mu g/l. The growth rate of the ciliate Tetrahymena pyriformis was slightly inhibit ed at 700 mu g/l, whereas other heterotrophic organisms (Daphnia magna and the nematode Caenorhabditis elegans) were not affected by isoprot uron up to concentrations of 1000 mu g/l. In the microcosm study appli cation of isoproturon to the microcosms up to a concentration of 90 mu g/l neither affected the abundance nor the community composition of t he phytoplankton, the zooplankton and the sediment dwelling nematodes. However, there was a distinct effect on anaerobic microbial degradati on activity in the sediment. Copyright (C) 1996 Elsevier Science Ltd.