# Joint temporal trends in river discharge and temperature over the past 57 years in a large European basin: implications for diadromous fish

Hanieh Seyedhashemi, Hilaire Drouineau, Anthony Maire, Florentina Moatar

► To cite this version:

Hanieh Seyedhashemi, Hilaire Drouineau, Anthony Maire, Florentina Moatar. Joint temporal trends in river discharge and temperature over the past 57 years in a large European basin: implications for diadromous fish. The European Geosciences Union (EGU), Apr 2023, Vienna, Austria. 2023, 10.5194/egusphere-egu23-7598. hal-04148794

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Submitted on 3 Jul 2023

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Distributed under a Creative Commons Attribution 4.0 International License
# Joint temporal trends in river discharge and temperature over the past 57 years in a large European basin: implications for diadromous fish

Hanieh Seyedhashemi¹, Hilaire Drouineau², Anthony Maire³, Florentina Moatar¹

¹ INRAE, UR RiverLy, Centre Lyon-Grenoble, 5 rue de la Doua CS 20244, 69625 Villeurbanne, France

² INRAE, Unité EABX – Écosystèmes Aquatiques et Changements Globaux, HYNES (Irstea-EDF R&D), 50 avenue de Verdun, 33612 Cestas Cedex, France

³ EDF R&D, LNHE - Laboratoire National d'Hydraulique et Environnement, 6 Quai Watier, 78401 Chatou, France

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## Introduction

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Climate change → modify river temperature (Tw), discharge (Q) and current velocity (V) → impact on migratory species

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How upstream migration of diadromous species has been affected over the past decades in a large basin ?

<figure><img src="image_5.png" /><figcaption>**Atlantic salmon**
*Salmo salar*</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>**Allis shad**
*Alosa alosa*</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>**Sea lamprey**
*P. marinus*</figcaption></figure>

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## Materials and method

* Daily counts of migrating individuals recorded at 4 fish passage stations (LOGRAMI)

* Daily times series of Tw and V over 1963-2019 reconstructed by a physically-based thermal model, coupled with a semi-distributed hydrological model (Seyedhashemi et al., 2022, 2023)

* Innovative “Choc” method, allowing to detect joint temporal trends in two environmental variables → to detect trends in Tw-V associations favorable for migration

### Fish passage stations:

1. Vichy on Allier

2. Decize on Loire

3. Châtellerault on Vienne

4. Descartes on Creuse

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Arevalo et al., 2020

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**Choc method**

Kernel density estimations
Mann-Kendall trend tests

Associations that ...

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* ✓ Identifying the favorable Tw-V associations effectively used by fish individual to migrate upstream

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* ✓ Detecting joint temporal trends in favorable Tw-V associations at the scale of the whole basin

<figure><img src="image_17.png" /><figcaption>Proportion of days with favorable Tw and V over migration period (%)</figcaption></figure>

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## Take-home messages

i) Significant decreases in the frequency of favorable Tw-V associations for upstream migration of Atlantic salmon with a considerable heterogeneity across the basin

ii) Significant increases for allis shad and sea lamprey at most stations

iii) Strong disparities in the consequence of global changes on fish migratory processes among species, seasons and tributaries.

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### References DOI:

Seyedhashemi et al., 2022: https://doi.org/10.5194/hess-26-2583-2022

Seyedhashemi et al., 2023: https://doi.org/10.5194/essd-2022-451

Arevalo et al., 2020: https://doi.org/10.1016/j.scitotenv.2020.141260

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