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REBECCA Project Meeting / WP4 / Activity Group 3 "Nutrients causing Eutrophication" - Chemical (nutrients) and ecological status in rivers: Ecoregion-based selection and modelling of relevant diatom assemblages related to chemistry.

Abstract : This meeting organized by the CEH Wallingford (UK) in Abingdon is an internal Rebecca / WP4 Meeting. The present t alk, given by Cemagref, makes the point of the work done on the French diatom dataset since the beginning of the project, A first purpose of our work was to make the part between the effects of the natural (abiotic) variation on diatom communities and the effect directly linked to anthropogenic disturbance. One usable way for doing is to investigate community biotypology and to link obtained clusters to a set of structuring abiotic variables. On the French territory, 11 different biotypes have been identified, 5 of them being driven by different natural abiotic conditions (i.e. 5 reference biotypes characterizing natural specific environments) and 6 other biotypes mainly drivent under influence of different kind and intensities of anthopogenic alteration. Another working orientation focuses on the reduction of species number, aiming at a simplification of a given national dataset without loosing structuring ecological information. With the help of the GSI, a structuring index set-up and published by our research team, it has been possible to greatly reduce the number of species (from 941 to 353) without significant loss of structuring ecological information. Working on 941 / versus 353 species with the INDVAL provide the same lists of structuring species by biotype (natural / altered by anthropogenic impact) which, on the base of a set of abiotic structuring parameters, have been linked with specific abiotic conditions. Then was presented the progress done by France concerning the setting-up of a national assessment system based on IPS, allowing to evaluate the ecological status of sites in a way that follows the WFD guidelines. 234 true reference sites have been selected, made of 5 natural biotypes. This natural framework has been then used to set-up a national assessment system using BDI. Assessment grids have then been built by natural region, expressed as EQR calculations on the basis of the adequate reference level per homogenous natural zone. These grids provide specific key values for quality class limits for 5 geographic zones consisting in a regroupment of HERs.
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https://hal.inrae.fr/hal-02610327
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Submitted on : Saturday, May 16, 2020 - 7:38:47 PM
Last modification on : Thursday, June 3, 2021 - 5:34:03 PM

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  • HAL Id : hal-02610327, version 1
  • IRSTEA : PUB00064451

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Juliette Tison-Rosebery, Y.S. Park, J.G. Wasson, Michel Coste, François Delmas. REBECCA Project Meeting / WP4 / Activity Group 3 "Nutrients causing Eutrophication" - Chemical (nutrients) and ecological status in rivers: Ecoregion-based selection and modelling of relevant diatom assemblages related to chemistry.. 6th FP REBECCA Project - WP4 - Activity Group 3 "Nutrients causing Eutrophication" : CEH Meeting, Oct 2004, Abingdon, United Kingdom. pp.25. ⟨hal-02610327⟩

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