EALTH Thesis: Long-term effects of chemical contamination of aquatic environments on the life history traits of the rose shrimp

Despite growing knowledge of the variability in population sensitivity within the environment, current approaches to ecological risk assessment (ERA) largely overlook the taxonomic and spatial heterogeneity of populations within species. Instead, they rely on toxicity data from a limited number of species and laboratory strains used as surrogates for the full species diversity of ecosystems (e.g. Daphnia, Hyalella or Americamysis for crustaceans). Consequently, current ERE frameworks continue to assume, in particular, that receiving aquatic environments are free of contaminants, with the exception of the chemical compound being assessed, on the basis that variability in sensitivity between populations can be ignored, as can potential cross-vulnerabilities to multiple environmental stressors.
It is against this backdrop that the ANR CRUScH grant was awarded (CRUStaceans facing CHemical contaminations: adaptability of riverine and marine populations, and vulnerability to environmental change, AAPG2025, 2026–2029). The main objectives of CRUScH are: (i) to conduct, for the first time, a large-scale assessment of the spatial variability in the sensitivity of aquatic populations to chemical contamination, (ii) to document the plastic or fixed nature of changes in tolerance to contaminants and the existence of differences in adaptive capacity between species or cryptic lineages, (iii) to assess the consequences of environmental exposure to multiple contaminants on the genetic diversity of populations, and (iv) their vulnerability to biotic or abiotic stressors. To this end, CRUScH draws on the study of two groups of crustacean species with contrasting phylogeographic and genetic characteristics: freshwater gammarids and marine palemonid shrimp.

the EALTH PhD project, funded entirely by the Normandy region, will draw on the in-depth expertise of UMR I-02 SEBIO in the biology of Palaemonidae and the work carried out as part of the ANR CRUScH project to address two key issues in ecotoxicology: (i) the plastic or fixed nature of organisms’ tolerance to chemical contaminants and (ii) the costs associated with long-term exposure to chemical contaminants in terms of vulnerability to two environmental stresses affecting ocean waters: heatwaves and ocean acidification. For the selection of populations to be studied in depth (long-term maintenance and development in the laboratory, transgenerational monitoring, cross-breeding, etc.), the EALTH thesis will draw on the large-scale spatial screening carried out as part of the CRUScH project (40 stations studied, from the Normandy coast to Galicia in Spain), the aim of which is, through exposure to various contaminants with different modes of action (trace metal elements, neurotoxic insecticides, PFAS, endocrine disruptors), to identify batches of populations tolerant to chemical contamination versus batches of populations sensitive to it.