Effect of interspecific competition on species sensitivity distribution models: Analysis of plant responses to chemical stress

Vincent Baillard (1) , Cécile Sulmon (2) , Anne‐kristel Bittebière (3) , Cendrine Mony (2) , Ivan Couée (2) , Gwenola Gouesbet (2) , Marie Laure Delignette-Muller (4) , Simon Devin (1) , Elise Billoir (1)

1 LIEC - Laboratoire Interdisciplinaire des Environnements Continentaux
2 ECOBIO - Ecosystèmes, biodiversité, évolution [Rennes]
3 BAH - Équipe 1 - Biodiversité et Adaptation dans les Hydrosystèmes
4 LBBE - Laboratoire de Biométrie et Biologie Evolutive - UMR 5558

Species Sensitivity Distributions (SSD) are widely used in environmental risk assessment to predict the con- centration of a contaminant that is hazardous for 5% of species (HC5). They are based on monospecific bioassays conducted in the laboratory and thus do not directly take into account ecological interactions. This point, among others, is accounted for in environmental risk assessment through an assessment factor (AF) that is applied to compensate for the lack of environmental representativity. In this study, we aimed to assess the effects of in- terspecific competition on the responses towards isoproturon of plant species representative of a vegetated filter strip community, and to assess its impact on the derived SSD and HC5 values. To do so, we realized bioassays confronting six herbaceous species to a gradient of isoproturon exposure in presence and absence of a compe- titor. Several modelling approaches were applied to see how they affected the results, using different critical effect concentrations and investigating different ways to handle multiple endpoints in SSD. At the species level, there was a strong trend toward organisms being more sensitive to isoproturon in presence of a competitor than in its absence. At the community level, this trend was also observed in the SSDs and HC5 values were always lower in presence of a competitor (1.12–11.13 times lower, depending on the modelling approach). Our dis- cussion questions the relevance of SSD and AF as currently applied in environmental risk assessment.

Mots clés: Species sensitivity distribution Environmental risk assessment Isoproturon Herbicide Biotic interaction Multi-stress; Species Sensitivity Distribution; environmental risk assessment; isoproturon; herbicide; biotic interaction; multi-stress

Domaines: Biodiversité et Ecologie

Vincent Baillard, Cécile Sulmon, Anne‐kristel Bittebière, Cendrine Mony, Ivan Couée, et al.. Effect of interspecific competition on species sensitivity distribution models: Analysis of plant responses to chemical stress. Ecotoxicology and Environmental Safety, 2020, 200, pp.110722. ⟨10.1016/j.ecoenv.2020.110722⟩. ⟨hal-02619516⟩