Interactions between Pesticides and Microorganisms in Freshwater Sediments Toxic Effects and Implications for Bioavailability

Widenfalk, A. 2005. Interactions between pesticides and microorganisms in freshwater sediments – Toxic effects and implications for bioavailability. Doctoral dissertation. ISSN 1652-6880, ISBN 91-576-7022-6. In aquatic ecosystems sediment microbial communities provide many important functions, such as organic matter decomposition and by constituting a major food source for organisms at higher trophic levels. Sediments are also sites were pesticides have been frequently detected. In this thesis, laboratory microcosm experiments on the interactions between pesticides and microorganisms in fresh-water sediments were performed. Natural microbial communities were exposed to both environmentally relevant and high concentrations of different pesticides. In short-term exposures, pesticides decreased overall microbial activity at concentrations that are predicted to be environmentally safe. Surprisingly, short-term exposure to the high pesticid