Ingénieur en Chef des Ponts, des Eaux et des Forêts / Senior scientist

email :

tel : +33 4 72 20 86 23

ORCID: 0000-0001-7431-2881





Key research topics and activities

  • Human impact on freshwater ecosystems

Multiple relevant scales, from reach to catchment, and multiple stressors (including land-use items, hydromorphological processes and alterations, substance transfers)

Responses of fish and invertebrates communities (taxonomic and traits diversity, stable isotopes approaches, links to ecotoxicology)

  • Bayesian hierarchical modeling

Bayesian inference in a hierarchical framework

Probabilistic risk approach, Bayesian Belief Networks

Joint Species Distribution Models

  • Development of tools and methods to help diagnostic and decision in the WFD and restoration contexts


Past projects:

  • OSCAR / Optimising the configuration of woody riparian buffers strips along rivers to enhance biodiversity and ecosystem services – Biodiversa3-2015-108
  • GAMBAS / Generating Advances in Modeling Biodiversity And ecosystem Services: statistical improvements and ecological relevance of joint species distribution models – APG ANR2018
  • SYRAH_CE / Risk assessment of hydromorphological structures and processes alteration – WFD tool (FR)
  • ARPEGES / Risk assessment of pollution due to pesticides – WFD tool (FR)
  • IBBHiS / Spatialized Hierarchical Bayesian analysis of Biodiversity Index



  • Post-doc

Mickael Le Gall (2018-2019) – OSCAR – Direct and indirect effects of woody riparian buffers at the catchment scale on macroinvertebrates diversity

  • Master students

Charlotte Guérineau (2019) – Modèles joints en écologie des communautés : application de modèles à variables latentes aux variations spatiales large-échelle des assemblages d’invertébrés en cours d’eau

Tiffany Pozzi (2016) – Relationships between woody riparian buffers and shredders invertebrates diversity, application of non-linear mixte models to count data

Delphine Corneil (2014) – Introducing spatial scales hierarchy in multi-stress models

Cyril Cavillon (2011) – Spatial dynamics of recolonization of the Loire Basin by otters and beavers

  • Tool development

Katell Mellac (2017) – development of a stakeholders-friendly interface for the ARPEGES model


List of publications

Piffady J, Carluer N, Gouy V, le Henaff G, Tormos T, Bougon N, Adoir E, Mellac K. 2020. Arpeges: A bayesian belief network to assess the risk of pesticide contamination for the river network of france. Integrated Environmental Assessment and Management.

Sarkis N, Geffard O, Souchon Y, Chandesris A, Ferreol M, Valette L, Alric B, Francois A, Piffady J, Chaumot A et al. 2020. How to quantify the links between bioavailable contamination in watercourses and pressures of anthropogenic land cover, contamination sources and hydromorphology at multiple scales? Science of the Total Environment. 735.

Godeau U, Bouget C, Piffady J, Pozzi T, Gosselin F. 2020. The importance of being random! Taking full account of random effects in nonlinear sigmoid hierarchical bayesian models reveals the relationship between deadwood and the species richness of saproxylic beetles. Forest Ecology and Management. 465.

Alric B, Geffard O, Chandesris A, Ferreol M, Francois A, Perceval O, Piffady J, Villeneuve B, Chaumot A. 2019. Multisubstance indicators based on caged gammarus bioaccumulation reveal the influence of chemical contamination on stream macroinvertebrate abundances across france. Environmental Science & Technology. 53(10):5906-5915.

Villeneuve B, Piffady J, Valette L, Souchon Y, Usseglio-Polatera P. 2018. Direct and indirect effects of multiple stressors on stream invertebrates across watershed, reach and site scales: A structural equation modelling better informing on hydromorphological impacts. Science of the Total Environment. 612:660-671.

Corneil D, Villeneuve B, Piffady J, Chandesris A, Usseglio-Polatera P, Souchon Y. 2018. Introducing nested spatial scales in multi-stress models: Towards better assessment of human impacts on river ecosystems. Hydrobiologia. 806(1):347-361.

Van Looy K, Piffady J, Floury M. 2017. At what scale and extent environmental gradients and climatic changes influence stream invertebrate communities? Science of the Total Environment. 580:34-42.

Van Looy K, Piffady J. 2017. Metapopulation modelling of riparian tree species persistence in river networks under climate change. Journal of Environmental Management. 202:437-446.

Bret V, Capra H, Gouraud V, Lamouroux N, Piffady J, Tissot L, Rivot E. 2017. Understanding inter-reach variation in brown trout (salmo trutta) mortality rates using a hierarchical bayesian state-space model. Canadian Journal of Fisheries and Aquatic Sciences. 74(10):1612-1627.

Van Looy K, Piffady J, Tormos T, Villeneuve B, Valette L, Chandesris A, Souchon Y. 2015. Unravelling river system impairments in stream networks with an integrated risk approach. Environmental Management. 55(6):1343-1353.

Calenge C, Chadoeuf J, Giraud C, Huet S, Julliard R, Monestiez P, Piffady J, Pinaud D, Ruette S. 2015. The spatial distribution of mustelidae in france. Plos One. 10(3).

Van Looy K, Piffady J, Cavillon C, Tormos T, Landry R, Souchon Y. 2014. Integrated modelling of functional and structural connectivity of river corridors for european otter recovery. Ecological Modelling. 273:228-235.

Piffady J, Parent E, Souchon Y. 2013. A hierarchical generalized linear model with variable selection: Studying the response of a representative fish assemblage for large european rivers in a multi-pressure context. Stochastic Environmental Research and Risk Assessment. 27(7):1719-1734.

Van Looy K, Cavillon C, Tormos T, Piffady J, Landry P, Souchon Y. 2013. A scale-sensitive connectivity analysis to identify ecological networks and conservation value in river networks. Landscape Ecology. 28(7):1239-1249.

Piffady J, Souchon Y, Capra H, Parent E. 2010. Quantifying the effects of temperature and flow regime on the abundance of 0+cyprinids in the upper river rhone using bayesian hierarchical modelling. Freshwater Biology. 55(11):2359-2374.