Fish biodiversity scenarios in the Seine basin under global change and connectivity constraints – SEINARIOS

Living organisms that face global change, and subsequent major environmental disruptions, have three options: to move and find more suitable environmental conditions, to adapt to new environmental conditions, or to extinct [1]. To better predict ecological dynamics and remedy biodiversity loss, several modelling approaches have been developed. However, the understanding and integration of species dispersal and extinction still require development, in particular when it comes to ecosystems highly fragmented by anthropogenic infrastructures [2,3]. Traditional models of fish species distribution that are habitat-centred do not explicitly take into account the quality neither the connectivity of landscape matrix and hydrological network across which the organisms migrate and disperse [4,5]. While ecological connectivity is a key concept in metacommunity ecology [6] and an essential property of the landscape to maintain biodiversity [7,8], its modelling is genuinely challenging [9–11], in particular in multi-taxa context [12] and anthropized ecosystems. The hydrological connectivity underlying the ecological connectivity is modified by different types of anthropogenic infrastructures (e.g. dams, sluices, channels) [2,13]. Furthermore, water flow variations [14,15] and growing drought periods [16] as expected in France, may modify both longitudinal and lateral connectivity [17,18], favour fish species invasions and/or extinctions [19,20], and amplify the consequences of global change on biodiversity [21]. To now, all these relationships and the corresponding uncertainties remain to be elucidated, characterized and quantified in order to better predict biodiversity distribution.

The thesis aims to address the following question: what is the role of connectivity and riverscape context in the future of biodiversity under global change and subsequent hydrological modifications in an anthropized basin?

To address this question, the work will mainly consist in analysing data and developing modelling approaches that can explicitly integrate hydroclimatic and landscape factors, as well as functional, longitudinal and lateral connectivity into predictive models of species distribution and of biodiversity. This will allow understanding the respective role of the different factors in species distribution. These models will then be used on scenarios of hydroclimatic, landscape and human development changes as projected in the basin in order to produce scenarios of future biodiversity. This work will apply on the particular case of the Seine basin, in virtue of the tight cooperation and partnership with the public Seine-Normandy Water Agency. The student will have several large datasets already available in the research unit (e.g. fish monitoring observations >1200 stations, river barriers, land-cover / land-uses, hydroclimatic archives and simulations). Some additional datasets will be built during the PhD in collaboration with the basin’s stakeholders (e.g. scenarios of future land, water and river uses). Collaborations with other INRAE research units (e.g. RiverLy in Lyon), and national and international institutions (e.g. via the on-going NAVIDIV project: https://www.fondationbiodiversite.fr/en/the-frb-in-action/programs-and-projects/le-cesab/navidiv/) to perform inter-basin and transnational comparisons will be strongly encouraged. Ultimately, these biodiversity scenarios accounting for global change and connectivity constraints will allow identifying and prioritizing areas for preserving ecological connectivity and biodiversity and provide guidance for sustainable basin management.

*Main activities*
The activities of the PhD will mainly consist in handling fish monitoring and environmental data, processing GIS data, use, adapt and develop connectivity models for fish species [e.g.22–26], develop and apply spatial-explicit statistical modelling of (joint) species distributions [e.g.27,28], build and handle scenarios of hydroclimatic, land-use and river use changes in collaboration with an transdisciplinary team, project future distribution of species and biodiversity depending on combinations of contrasted scenarios, and estimate the uncertainties across the different steps of the work [e.g.29–31].

*PhD location & supervision*
The PhD student will be hosted by the research unit Anthropized Continental Hydrosystems – Resources, Risks, Restoration HYCAR at INRAE, located in Antony (92, Ile-de-France region, France).

HYCAR (https://www6.jouy.inrae.fr/hycar) gathers competencies in hydrology, ecology and ecological engineering. Its topics of research include water resources and risks (estimation, prediction and management), ecological functioning and restoration of freshwater ecosystems under multiple anthropogenic pressures across scales, and modelling and remediation of pollutant transfer from agricultural practices. In this research unit, the PhD student will belong to the team River Hydroecology (https://hef.inrae.fr/).

He/she will be co-supervised by the lab Evolution & Biological Diversity (University of Toulouse, France), and more specifically, by the team AQUAECO (https://edb.cnrs.fr/recherche/equipe-aquaeco/) that works on the impacts of climate change, ecosystem fragmentation, biological invasions and resource overexploitation in freshwater ecosystems. The student will belong to the Graduate School SEVAB in Toulouse. In virtue of this co-supervision and graduate school location, she/he will sometimes have to travel between Antony and Toulouse (c.a. twice a year).

This thesis will be co-supervised by Dr. Aliénor Jeliazkov (metacommunity ecology; INRAE Antony), Dr. Guillaume Thirel (hydroclimatology; INRAE Antony) and Prof. Gaël Grenouillet (habilitated; fish community ecology under scenarios of global change; EDB lab). The student will benefit from the support and expertise of the River Hydroecology team, including Dr. Jérôme Belliard (fish communities of the Seine river basin) and Dr. Céline Le Pichon (functional connectivity in freshwater ecosystems).

*Funding, salary & working environment*
The PhD is co-funded by the INRAE’s research program Biosefair “Promote biodiversity and strengthen networks of ecosystem services” and the public Seine-Normandy Water Agency.

Provisional net salary: 1,506 EUR / month (gross salary: 1,874 EUR / month). Travels fees in relation to the PhD work will be covered.

On-site access to institutional catering, sport & culture club, and car parking facilities. Easy access by public transport (https://www6.jouy.inrae.fr/hycar/Comment-venir-a-INRAE-Antony/Acces); at one hour from amazing Paris.

*Starting date & duration*
The PhD is for a three-year duration. It can start from the 1st of October 2021 and at latest the 1st of December 2021.

*Expected skills*
Required: MSc degree (Master of Science) in Ecology; Experience in research; Experience in statistical modelling; Abilities in GIS processing
Highly recommended: Experience in species distribution modelling and/or ecological connectivity modelling; Experience with freshwater ecosystems
Potential assets: Knowledge on fish communities; Inclination towards metacommunity ecology; Drawn to inter- and transdisciplinary work (ecology, hydroclimatology and links with water-related stakeholders).

*To apply to the position:*
The application should include:
(1) CV
(2) cover letter showing your interest in the topic and your personal vision of the research to be realised (2 pages max.)
(3) the name and contact details of 2 to 5 reference persons
(4) if possible, MSc degree diploma and/or prelims transcript of marks or equivalent.

Send your application by email _with [phdseinarios] in the mail subject_ to all the supervisory team (5 members) : Alienor Jeliazkov (alienor.jeliazkov@inrae.fr), Guillaume Thirel (guillaume.thirel@inrae.fr), Gaël Grenouillet (gael.grenouillet@univ-tlse3.fr), Jérôme Belliard (jerome.belliard@inrae.fr) and Céline Le Pichon (celine.lepichon@inrae.fr).

*For any question, please feel free to contact us.*

*Application deadline:* 15th of August 2021
The interviews will be held as we go along the recruitment process.

*Cited literature references*
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3. Zajicek, P., Radinger, J. & Wolter, C. Disentangling multiple pressures on fish assemblages in large rivers. Sci. Total Environ. 627, 1093–1105 (2018).
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20. Bergerot, B., Hugueny, B. & Belliard, J. When Local Extinction and Colonization of River Fishes Can Be Predicted by Regional Occupancy: the Role of Spatial Scales. PLOS ONE 8, e84138 (2013).
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25. Le Pichon, C., Tales, É., Gorges, G., Baudry, J. & Boët, P. Using a continuous riverscape survey to examine the effects of the spatial structure of functional habitats on fish distribution. J. Freshw. Ecol. 31, 1–19 (2016).
26. Hodgson, J. A., Wallis, D. W., Krishna, R. & Cornell, S. J. How to manipulate landscapes to improve the potential for range expansion. Methods Ecol. Evol. 1558–1566 (2017) doi:10.1111/2041-210X.12614@10.1111/(ISSN)2041-210X.Biogeography.
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28. Schliep, E. M. et al. Joint species distribution modelling for spatio-temporal occurrence and ordinal abundance data. Glob. Ecol. Biogeogr. 27, 142–155 (2018).
29. Buisson, L., Thuiller, W., Casajus, N., Lek, S. & Grenouillet, G. Uncertainty in ensemble forecasting of species distribution. Glob. Change Biol. 16, 1145–1157 (2010).
30. Stoklosa, J., Daly, C., Foster, S. D., Ashcroft, M. B. & Warton, D. I. A climate of uncertainty: accounting for error in climate variables for species distribution models. Methods Ecol. Evol. 6, 412–423 (2015).
31. Lemaitre-Basset, T. et al. Climate change impact and uncertainty analysis on hydrological extremes in a French Mediterranean catchment. Hydrol. Sci. J. 66, 888–903 (2021).

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