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Importance des processus de dispersion au sein des communautés de diatomées, et impact sur les méthodes de bioindication (IBD)

Abstract : The structuring of biotic communities nowadays appears to be the result of an interaction between deterministic and stochastic processes. Environmental filtering and dispersion processes appear to be determining factors for the structuring of communities, but their relative importance is still poorly understood because they are conditioned by the spatial scales and levels of anthropisation considered. While multi-scale quantitative approaches are therefore strongly recommended to better understand how local and regional processes affect communities, they are still too rare in the literature. We have thus tried to set up this type of study, taking as a model organism the diatoms, primary producers playing a key role in aquatic ecosystems. The objective was to understand the role of deterministic and stochastic processes in the structuring of benthic diatom meta-communities in rivers subjected to different levels of eutrophication, depending on the position of the site in the hydrographic network. Our work has led to the development of an innovative method capable of measuring the influence mass effect on diatom communities. The mass effect allows a species to survive outside its environmental optimum thanks to the constant arrival of individuals through an immigration process, thus leading to a strong homogenization of communities. A better understanding of this mechanism represents a significant step forward, particularly in the context of the global decline in biodiversity. This phenomenon also has an impact on bio-indication methods for environmental quality, since the presence of species in habitats that are a priori unfavourable to them can potentially mask the effect of local environmental conditions on communities, and thus induce a bias in the assessment of the ecological status of watercourses. Our results are in line with this, revealing that taking this process into account when calculating Diatom Biological Index allows a more effective response of the scores to the local environment, thus highlighting the importance of taking dispersion processes into account when developing new bio-indication methods.
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Contributor : Migration Irstea Publications <>
Submitted on : Saturday, May 16, 2020 - 3:48:12 PM
Last modification on : Friday, February 5, 2021 - 3:55:23 AM


  • HAL Id : hal-02608298, version 1
  • IRSTEA : PUB00059520



Juliette Tison-Rosebery, Aurélien Jamoneau, Thibault Leboucher. Importance des processus de dispersion au sein des communautés de diatomées, et impact sur les méthodes de bioindication (IBD). [Rapport de recherche] irstea. 2018, pp.36. ⟨hal-02608298⟩



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