Influence of the natural growth environment on the sensitivity of phototrophic biofilm to herbicide
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Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level structural responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial supports placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatisation phase of 7 days were exposed to alachlor at 10 and 30 μg L−1 for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash-free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The structural responses of bacterial and diatom communities were difficult to distinguish from changes linked to the microcosm incubation period. Phototrophic biofilms from site S exposed at 30 μg L−1 alachlor were characterised by an increase of Achnanthidium minutissimum (K-z.) Czarnecki abundance, as well as a higher proportion of abnormal frustules. Thus, phototrophic biofilms with different histories, exhibited different responses to alachlor exposure demonstrating the importance of growth environment. These observations also confirm the problem of distinguishing changes induced by the stress of pesticide toxicity from temporal evolution of the community in the microcosm.
KeywordsAlachlor Phototrophic biofilms Bacterial community Diatoms Growth environment Biological succession Microbial ecotoxicology
This work was funded by the French National Programme EC2CO-Environmental Microbiology—and by the Midi-Pyrénées Council Programme of the Pyrenean working community. We thank J. Ferriol and D. Dalger for assistance with the DGGE and water chemistry analysis, respectively. We also thank the ‘Association des Agriculteurs d’Auradé’ for the access to site M.
- Chesters G, Simsiman GV, Levy J, Alhajjar BJ, Fathulla RN, Harkin JM (1989) Environmental fate of alachlor and metolachlor. Rev Environ Contam Toxicol 110:1–74Google Scholar
- Debenest T (2007) Characteristics of impact of agricultural pollutions on the benthic diatoms. PhD thesis, Université de Bordeaux 1, Bordeaux (in French)Google Scholar
- Debenest T, Silvestre J, Coste M, Pinelli E (2010) Effects of pesticides on freshwater diatoms. Whitacre DM (ed) Reviews of environmental contamination and toxicology, 87. Reviews of environmental contamination and toxicology 203Google Scholar
- Geiszinger A, Bonnineau C, Faggiano L, Guasch H, Lopez-Doval JC, Proia L, Ricart M, Ricciardi F, Romani A, Rotter S, Munoz I, Schmitt-Jansen M, Sabater S (2009) The relevance of the community approach linking chemical and biological analyses in pollution assessment. Trends Anal Chem 28:619–626CrossRefGoogle Scholar
- Muyzer G, Brinkhoff T, Nubel U, Santegoeds C, Schafer H, Wawer C (1997) Denaturing gradient gel electrophoresis (DGGE) in microbial ecology. In: Kowalchuk GA, De Bruijn FJ, Head IM, Akkermans D, Van Elsa JD (eds). Kluwer Academic Dordrecht, pp 1–27Google Scholar
- Payraudeau S, Junker P, Imfeld G, Gregoire C (2009) Characterizing hydrological connectivity to identify critical source areas for pesticides losses. In: 18thWorld IMACS/MODSIM Congress: Interfacing modelling and simulation with mathematical and computational sciences, Cairns, Australia, 1879–1885Google Scholar
- Stevenson RJ, Bothwell ML, Lowe RL (1996) Algal ecology: freshwater benthic ecosystems. Academic Press, San Diego, 753 ppGoogle Scholar