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Article Dans Une Revue Freshwater Biology Année : 2002

Simple predictions of instream habitat model outputs for fish habitat guilds in large streams

Simplification des modèles d'habitat pour des guildes de poissons (grands cours d'eau)

Yves Souchon

Résumé

In the context of a generalised modification of hydraulic conditions in medium to large streams, modelling the impacts of stream regulation on fish communities in multiple streams is an important challenge for basic and applied freshwater ecology. Conventional instream habitat models such as PHABSIM link a hydraulic model with preference curves for various species to estimate habitat value changes with discharge in stream reaches. Despite worldwide applications, they have been scarcely used in multiple sites with multiple species. We assigned 21 size classes of European fish species to four habitat guilds (cluster analysis grouping size classes with comparable microhabitat preference curves). Then, we ran a conventional instream habitat model on 28 French stream reaches belonging to the 'barbel zone', to estimate habitat values vs discharge curves for the 21 size classes. We summarized the outputs as mean habitat values for guilds, and tested if they were predictable from average characteristics of reaches (discharge, depth, width, particle size). As was obtained elsewhere for populations, habitat values for guilds were strongly related to average, dimensionless characteristics of reaches. The Reynolds number of reaches, equivalent to a discharge per width unit, reflected most of the discharge-dependent changes in habitat values (within reaches). In particular, habitat values of species preferring bank (respectively midstream) microhabitats decreased (respectively increased) with increasing Reynolds number. The Froude number at median discharge was the major predictor of reach-dependent but discharge-independent variations in habitat values. Habitat values of species preferring riffle vs pool or bank microhabitats were higher in reaches with high Froude numbers. These relationships were consistent with existing knowledge on the different species.Such results suggest that the input variables required to estimate habitat values for fish communities can be greatly simplified, as illustrated by a general estimation of the sensitivity of species preferring midstream habitats to discharge changes in any reach. Cost-efficient alternatives to conventional instream habitat models should facilitate their validation in multiple sites, a point that remains critical in instream habitat modelling for fish communities.
Les modèles d'habitat pour les guildes de poissons (grands cours d'eau) peuvent être fortement simplifiés, car leurs sorties dépendent des caractéristiques hydrauliques moyennes des cours d'eau (nombre de Froude et de Reynolds), eux même combinaison du débit, de la largeur, de la hauteur moyenne du cours d'eau.

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Dates et versions

hal-02580749 , version 1 (14-05-2020)

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Citer

Nicolas Lamouroux, Yves Souchon. Simple predictions of instream habitat model outputs for fish habitat guilds in large streams. Freshwater Biology, 2002, 47, pp.1531-1542. ⟨10.1046/j.1365-2427.2002.00880.x⟩. ⟨hal-02580749⟩
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