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Variations in periphytic diatom tolerance to agricultural pesticides in a contaminated river: An analysis at different diversity levels

Abstract : Periphytic diatoms are an important phototrophic component of river biofilm and are used in situ for the bioindication of pollution as well as in laboratory ecotoxicological tests to assess the toxicity of contaminants. In spring 2009, phototrophic biofilm samples mostly com-posed of diatoms were collected in a small river and their sensitivity to the herbicide diuron was estimated via pho-tosynthesis bioassays. A large difference in tolerance to diuron was demonstrated between two periphytic communities from an upstream unpolluted site and a down-stream site subjected to high seasonal contamination by pesticides. The comparison of diatom community struc-ture between sites revealed important variations of the relative abundance of some species which could explain this difference. Consequently, some of these species were isolated from the river in autumn when toxic pressure was low, and kept in culture for more than six months in uncontaminated water. Acute toxicity tests of diuron based on growth inhibition were then performed on each spe-cies. Surprisingly the sensitivities of the species as esti-mated by EC50 were almost the same. However two strains of another species that could be isolated from each site of the river showed significant differences in toler-ance to diuron and copper, another contaminant of the river. These results suggest the importance of adaptation at the intraspecific level in the induction of periphytic community tolerance to toxicants. Thus, they portend difficulties to fairly assess toxic pollution effects in situ with classical bioindication field methods at the community level.
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https://hal.inrae.fr/hal-02597388
Contributor : Migration Irstea Publications <>
Submitted on : Friday, May 15, 2020 - 10:31:16 PM
Last modification on : Thursday, June 3, 2021 - 5:34:03 PM

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  • HAL Id : hal-02597388, version 1
  • IRSTEA : PUB00036087

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V. Roubeix, Stéphane Pesce, Nicolas Mazzella, Michel Coste, François Delmas. Variations in periphytic diatom tolerance to agricultural pesticides in a contaminated river: An analysis at different diversity levels. Fresenius Environmental Bulletin, 2012, 21 (8), pp.2090-2094. ⟨hal-02597388⟩

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