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Diatom communities natural variability and anthropogenic pressure effects: the interest of hydro-ecoregions

Abstract : Our poor ability to appreciate diatom communities natural variability often leads us to a wrong evaluation of aquatic ecosystem quality. But if we succeed, for both altered and non altered conditions, in linking river types to diatom community types, it becomes possible to develop management tools integrating this variability. Classification is, thus, a critical step in many bio-assessment programs. In France, a set of abiotic parameters (geology, climate, altitude,~) are used to divide the hydrographic network into different homogeneous "hydro-ecoregions" (Wasson et al., 2002). But to what extent can this typological classification account for diatoms natural variability ? How do these communities react to anthropogenic pressure ? Is it a predictable response ? These are the questions we tried to answer. Then we gathered more than 800 diatom samples coming from the different hydro-ecoregions of France. 30% of these samples, situated in weakly impacted conditions, allowed us to define the importance of the diatom communities spatial fluctuations due to natural variability. The other stations illustrated the way those communities were modified by anthropogenic pressure. This classification, linking the different environmental situations encountered in our basin (river type x alteration intensity) to the corresponding diatom community structure, should allow us to initiate a predictive approach. At the end of this second step, we hope we will be able to predict from environmental parameters what the diatom community should be like, and then to reveal possible ecosystem damage. Classification was performed thanks to artificial neural networks (self-organizing maps). This research was carried out in support of the Water Framework Directive settlement.
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Contributor : Migration Irstea Publications <>
Submitted on : Thursday, May 14, 2020 - 10:54:09 PM
Last modification on : Thursday, June 3, 2021 - 5:34:03 PM


  • HAL Id : hal-02584157, version 1
  • IRSTEA : PUB00016552



Juliette Tison-Rosebery, Michel Coste, François Delmas, L. Ector, Y.S. Park, et al.. Diatom communities natural variability and anthropogenic pressure effects: the interest of hydro-ecoregions. 7 th AEHMS Congress, Lyon, 15-17/09/03, 2003, pp.16. ⟨hal-02584157⟩



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