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Acquisition de tolérance et modification de structure des communautés périphytiques : une réponse précoce à la pression urbaine dans les milieux aquatiques

Abstract : Urban aquatic ecosystems are these days contaminated by mixtures of micropollutants of diverse types and origins. Such contaminations, which are multiple, chronic and non-lethal, raise increasing concern among the scientific community. Indeed, a precise evaluation of exposure levels is difficult to obtain. Moreover, establishing a causal link between contamination and the induced biological response of aquatic organisms is complex as no direct and visible effects can be observed. The aim of this study is to develop a methodology for the use of periphyton as a biomarker of urban pollution. Biofilms are complex aquatic communities and play an important role in aquatic ecosystems. Their response to a disruption can be assessed both in terms of structure or functional modifications. Our first step was to develop both a PICT approach with a new short-term toxicity test to measure the tolerance to metal of the heterotrophic component of biofilms and the use of a fingerprinting technique (ARISA) to reveal structure modifications of both bacterial and eukaryotic communities. The methodologies thus developed were tested in a microcosm study by exposing periphyton to metals at environmental levels. They were then used in field studies: first in a multi-metallic gradient along the Seine river by punctual sampling of natural periphyton and also in a translocation study (upstream/downstream the Paris urban area). Furthermore, the link between biofilm tolerance levels and the global metallic contamination was explored at the watershed scale. It is hoped that the future use of this approach will help to understand the impacts of human activities, especially toxic pressure, on aquatic ecosystems
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  • HAL Id : tel-00596853, version 1

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Lise Fechner. Acquisition de tolérance et modification de structure des communautés périphytiques : une réponse précoce à la pression urbaine dans les milieux aquatiques. Sciences de la Terre. Université Paris-Est, 2010. Français. ⟨NNT : 2010PEST1062⟩. ⟨tel-00596853⟩

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