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Communication Dans Un Congrès Année : 2011

Variations in periphytic diatom tolerance to agricultural pesticides in a contaminated river: An analysis from community to population level

Variations de tolérance aux pesticides agricoles des diatomées périphytiques dans une rivière contaminée : une analyse de l'échelle des communautés à celle des populations

Résumé

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 composed mostly of diatoms were collected in a small river and their sensitivity to the herbicide diuron was estimated via photosynthesis bioassays. A large difference in tolerance to diuron was demonstrated between two periphytic communities from an upstream unpolluted site and a downstream site subjected to high seasonal contamination by pesticides. The comparison of diatom community structure 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 species. Surprisingly the sensitivities of the species as estimated 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 tolerance 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 and the probably low sensitivity of bioindication methods to assess river contaminations.
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Dates et versions

hal-02167854 , version 1 (28-06-2019)

Identifiants

Citer

V. Roubeix, S. Pesce, Nicolas Mazzella, Michel Coste, François Delmas. Variations in periphytic diatom tolerance to agricultural pesticides in a contaminated river: An analysis from community to population level. 3rd International Conference on Environmental Management, Engineering, Planning and Economics (CEMEPE 2011) & SECOTOX Conference, Jun 2011, Skiathos, Greece. pp.343-347. ⟨hal-02167854⟩

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