Exposures in realistic environmental conditions are essential to properly assess the effects of emerging pollutants on ecosystems. While ceria nanoparticles (nCeO 2) production and use are expanding quickly, ecotoxicity studies remain very scarce. In this work, we set up experimental systems reproducing a simplified ecosystem to assess the effects of a chronic exposure to citrate-coated nCeO 2 (ci-CeO 2) and bare nCeO 2 (ba-CeO 2) on the freshwater mussel Dreissena polymorpha using an inte‐ grated multibiomarker approach. The fate of nanoparticles was tightly monitored to properly characterize the exposure. Organisms were exposed for three weeks and sampled weekly for biomarker analysis. Mussel filter-feeding activity resulted in significant removal of nCeO 2 from the water column. At the same time, bioaccumu‐ lation was low, reaching its maximum in the first week. Mussels bioaccumulated ci-CeO 2 three times more than ba-CeO 2 , probably due to coating-related differences in their behavior in the water column and in organisms. Meanwhile, biomarker results were integrated and synthesized using linear discriminant analysis, highlighting that pi-glutathione-S-transferase (piGST) mRNA, catalase (CAT) activity, and lysosomal system were the most impacted of the seven biomarkers singled out by the discriminant analysis. These biomarker responses indicated that mussels exposed to both forms of nCeO 2 were stressed and differentiate from the controls. Moreover,theyresponded differently to ba-CeO 2 and ci-CeO 2 exposure. How‐ ever, biomarkers used in the experimental conditions of the present study did not indicate severe nCeO 2 toxicity on mussels, as cellular damage biomarkers and mussel filtering activity were left unimpaired. However, further studies are needed to investigate if the slight perturbations observed could lead to populational impacts in the long-term.