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Interactions between pesticides and microorganisms in freshwater sediments

toxic effects and implications for bioavailability

Widenfalk, Anneli (2005). Interactions between pesticides and microorganisms in freshwater sediments. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2005:23
ISBN 91-576-7022-6
[Doctoral thesis]

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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 pesti-cides have been frequently detected. In this thesis, laboratory microcosm experi-ments 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 pesticide concentrations did not always affect the microbial activity. Long-term exposures (one month), were observed to induce different shifts in the microbial community composition, detected by using molecular methods, depending both on the type of pesticide and the concentrations applied. Hence, toxic effects of pesticides in microorganisms are not always straightforward and easy to interpret. The microbial community of an artificial sediment used in toxicity tests was shown to have a low microbial activity, biomass, diversity as well as a different community composition compared to natural sediments. This could have impli-cations for the fate of the test compound and the outcome of the toxicity tests, which may need to be considered when interpreting the toxicity test results. Sediment bacteria and their extracellular polymeric substances (EPS) in biofilms were observed to increase the uptake and bioaccumulation of the hydrophobic pesticide chlorpyrifos to midge larvae, Chironomus riparius. This indicates that microorganisms and EPS may increase the bioavailability and be important vectors for the uptake of sediment-associated contaminants in aquatic food webs. Hence, the quality of the sediment organic carbon may need to be taken in consideration in toxicity tests and risk assessments of these pollutants. This thesis shows that sediment microorganisms can be affected by pesticide exposure and that they can affect pesticide bioavailability. Therefore, the role of microbial processes should be regarded in risk assessments of pesticides.

Authors/Creators:Widenfalk, Anneli
Title:Interactions between pesticides and microorganisms in freshwater sediments
Subtitle:toxic effects and implications for bioavailability
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2005
Number of Pages:38
ALLI. Widenfalk, A., Svensson, J.M., Goedkoop, W. 2004. Effects of the pesticides captan, deltamethrin, isoproturon, and pirimicarb on the microbial community of a freshwater sediment. Environmental Toxicology and Chemistry 23, 1920-1927. II. Widenfalk, A., Bertilsson, S., Sundh, I., and Goedkoop, W. Effects of agricultural pesticides on community composition and activity of sediment microorganisms – Responses at various levels of microbial organization. (Submitted manuscript) III. Goedkoop, W., Widenfalk, A., Haglund, A., Steger, K., and Bertilsson, S. Microbial characterization of artificial sediment and comparisons with natural sediment – Implications for toxicity testing. Environmental Toxicology and Chemistry (Accepted) IV. Widenfalk, A., Lundqvist, A., and Goedkoop, W. Sediment bacteria and microbial biofilms mediate the uptake and bioaccumulation of chlorpyrifos in Chironomus riparius (Chironomidae, Diptera). (Manuscript)
Place of Publication:Uppsala
ISBN for printed version:91-576-7022-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P10 Water resources and management
Subjects:Not in use, please see Agris categories
Agrovoc terms:pesticides, toxicity, microorganisms, invertebrates, freshwater, sediment, bioavailability, environmnental impact assessment
Keywords:microbial communities, PLFA, T-RFLP, biofilms, EPS, toxicity tests, artificial sediment, hydrophobic contaminants, benthic invertebrates
Permanent URL:
ID Code:770
Department:(NL, NJ) > Dept. of Environmental Assessment (until 080831)
Deposited By: Anneli Widenfalk
Deposited On:22 Feb 2005 00:00
Metadata Last Modified:02 Dec 2014 10:07

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