DUGi

Effects of low concentrations of the phenylurea herbicide diuron on biofilm algae and bacteria

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A system of recirculating channels was used in this study to examine the long-term effects (29 d) of environmentally realistic concentrations of the herbicide diuron (from 0.07 to 7 μg L-1) on biofilm communities. The autotrophic activity of biofilms was affected by this herbicide, as reflected by a marked decrease in the photosynthetic efficiency. Diuron exposure also increased chlorophyll-a content and reduced the biovolume of diatom taxa at low concentrations. The effects on bacteria were also remarkable. Bacterial abundance was reduced after a week of exposure to the herbicide at a range of concentrations. Effects were on the number of live bacteria and on the increase in the leucine-aminopeptidase activity. It is suggested that inputs of herbicides to the river ecosystem at low concentrations may cause a chain of effects in the biofilm, which include inhibitory effects on algae but also indirect effects on the relationships between biofilm components. © 2009 Elsevier Ltd. All rights reserved

This study was supported by the European Commission project Modelkey (Project 511237-2 GOCE). Additional funds were provided by the European Project Keybioeffects (MRTN-CT-2006-035695) and by the Spanish Ministry of Science and Technology (Project GCL2006-12785/HID) and the VIECO program (009/RN08/011) of the Spanish Ministry of the Environment and Rural and Marine Affairs

Elsevier