Effects of nanosilver on Mytilus galloprovincialis hemocytes and early embryo development

Silver nanoparticles (AgNP), one of the main nanomaterials for production and use, are expected to reach theaquatic environment, representing a potential threat to aquatic organisms. In this study, the effects of bareAgNPs (47 nm) on the marine mussel Mytilus galloprovincialis were evaluated at the cellular and whole organismlevel utilizing both immune cells (hemocytes) and developing embryos. The effects were compared with those ofionic Ag+(AgNO3). In vitro short-term exposure (30 min) of hemocytes to AgNPs induced small lysosomalmembrane destabilization (LMS EC50= 273.1 μg/mL) and did not affect other immune parameters (phagocy-tosis and ROS production). Responses were little affected by hemolymph serum (HS) as exposure medium incomparison to ASW. However, AgNPs significantly affected mitochondrial membrane potential and actin cy-toskeleton at lower concentrations. AgNO3showed much higher toxicity, with an EC50= 1.23 μg/mL for LMS,decreased phagocytosis and induced mitochondrial and cytoskeletal damage at similar concentrations.Both AgNPs and AgNO3significantly affected Mytilus embryo development, with EC50= 23.7 and 1 μg/L,respectively. AgNPs caused malformations and developmental delay, but no mortality, whereas AgNO3mainlyinduced shell malformations followed by developmental arrest or death.Overall, the results indicate little toxicity of AgNPs compared with AgNO3; moreover, the mechanisms ofaction of AgNP appeared to be distinct from those of Ag+. The results indicate little contribution of released Ag+in our experimental conditions. These data provide a further insight into potential impact of AgNPs in marineinvertebrates