The increasing use of nanomaterials and the release of nanoparticles (NPs) into the environment raise concerns about their ecological impacts. This thesis investigates the biological responses of freshwater gastropods to silver nanoparticles (AgNPs), aiming to support the development of Adverse Outcome Pathways (AOPs). Combining approaches from physical chemistry, ecotoxicology, molecular biology, and ecology, it focuses on how AgNPs physicochemical properties and exposure routes affect uptake, transformation, and biological effects in Lymnaea stagnalis. The proposed AOP begins with citrate-coated AgNPs undergoing aggregation and limited dissolution in freshwater. Following uptake, their interaction with plasma proteins leads to dynamic bio-corona formation (MIE), triggering oxidative stress, altered glutathione metabolism, and energy imbalance. These molecular disruptions activate antioxidant and immune responses, increase lipid peroxidation, and suppress hemocyte counts. Tissue-level effects include AChE inhibition and energy imbalances in the hepatopancreas. Organism-level outcomes involve reduced reproduction, delayed development, and lower condition indices, persisting into the next generation. Trophic transfer and route-specific detoxification further illustrate how AgNPs toxicity propagates across biological levels, informing nanoparticle risk assessment in freshwater invertebrates.