Silver exists in nature both as compounds, such as silver nitrate (AgNO₃), and in particulate forms including microparticles and nanoparticles. Due to its widespread use in industries such as cosmetics and textiles, silver poses potential risks to both environmental and human health. This study aimed to evaluate the toxic effects of different silver forms on freshwater crayfish. For this purpose, the 48-hour sublethal effects of 0.1 and 1mg/L concentrations of AgNO₃, silver microparticles (AgMPs), and silver nanoparticles (AgNPs) were assessed based on hemolymph parameters, tissue biochemistry, and histopathological alterations. A considerable reduction in total hemocyte count was observed in crayfish exposed to AgNO₃. Biochemical responses in gill and hepatopancreas tissues varied depending on the type of silver compound administered. Histopathological analysis revealed no notable alterations in the antennal gland, muscle, gonads, heart, or digestive system across all treatment groups. However, exposure to AgNO₃ led to lamellar degeneration, hemocytic infiltration, and epithelial hyperplasia in the gills. Moreover, tissue damage severity in gill and hepatopancreas varied according to the particle size of the silver material. These findings suggest that silver-based substances, particularly in nanoparticulate forms, should be carefully examined for their potential ecological risks. Differences in particle size may result in varying degrees of toxicity in aquatic organisms.

To Cite This Article: Şimsek I, Arslan Yuce P, Gul G, Gunal AÇ, Kuzukiran O and Filazi A 2025. Evaluation of toxic effects of silver micro and nanoparticles and silver nitrate in crayfish (Astacus leptodactylus). Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2025.218