ToF-SIMS imaging shows specific lipophilic vitamin alterations in chronic reprotoxicity caused by the emerging contaminant Pravastatin in Gammarus fossarum.

Blood lipid-lowering agents, such as Pravastatin, are among the most frequently used pharmaceuticals released into the aquatic environment. Although their effects on humans are very well understood, their consequences on freshwater organisms are not well known, especially in chronic exposure conditions. Gammarus fossarum is commonly used as sentinel species in ecotoxicology because of its sensitivity to a wide range of environmental contaminants and the availability of standardized bioassays. Moreover, there is an increased interest in linking molecular changes in sentinel species, such as gammarids, to observed toxic effects. Here, we performed a reproductive toxicity assay on females exposed to different concentrations of pravastatin (30; 300; 3,000 and 30,000 ng L-1) during two successive reproductive cycles and we applied ToF-SIMS imaging to evaluate the effect of pravastatin on lipid homeostasis in gammarids. Reproductive bioassay showed that pravastatin could affect oocyte development in Gammarus fossarum inducing embryotoxicity in the second reproductive cycle. Mass spectrometry imaging highlighted the disruption in vitamin E production in the oocytes of exposed female gammarids at the second reproductive cycle, while limited alterations were observed in other lipid classes, regarding both production and tissue distribution. The results demonstrated the interest of applying spatially resolved lipidomics by mass spectrometry imaging to assess the molecular effects induced by long-term exposure to environmental pharmaceutical residues in sentinel species.

Assessment of the impact of chemical pollution on endangered migratory fish in two major rivers of France, including spawning grounds.

Water pollution is a one of the most contributors to aquatic biodiversity decline. Consequently, ecological risk assessment methods have been developed to investigate the effects of existing stresses on the environment, including the toxic effects of chemicals. One of the existing approaches to quantify toxic risks is called "Potentially Affected Fraction of species" (PAF), which estimates the potential loss of species within a group of species studied. In this study, the PAF method was applied to the Garonne catchment (southwest France) due to the limited information available on the involvement of water pollution in the decline of diadromous fish populations. This approach was used to quantify the potential toxic risk associated with chemical contamination of water for fish species. The objectives were to quantify this risk (1) in the Garonne and Dordogne rivers and (2) in the spawning grounds of two endangered anadromous fish species: the allis shad and the European sturgeon during the development period of their early life stages. Environmental pollution data was provided for 21 sites within the Garonne catchment between 2007 and 2022, and toxicity data was obtained specifically from freshwater toxicity tests on fish species. Then, for each site and each year, the potential toxic risk for a single substance (ssPAF) and for a mixture of substances (msPAF) was calculated and classified as high (>5 %), moderate (>1 % and < 5 %) or low (<1 %). Potential toxic risks were mostly moderate and mainly associated with: metals > other industrial pollutants and hygiene and care products > agrochemicals. In summary, this study highlights the probable involvement of water contamination on the decline, fate and restoration of diadromous fish populations in the Garonne catchment, focusing notably on the toxic effects on early life stages, a previously understudied topic.