Bioaccumulation and toxicity of NiO nanoparticles in Gracilaria lemaneiformis

Little is known about the potential behavior and ecotoxicity of nanoparticles to aquatic organisms. To carefully address this issue, we conducted a comprehensive toxicity assessment, including NiO nanoparticles accumulation and toxicity tests as well as Lipid peroxidation (LPO), MDA content, mitochondrial depolarization and Reactive oxygen radical (ROS) analysis using Gracilaria lemaneiformis as a model organism. Our results demonstrated that the concentration of NiO Nanoparticles accumulated in Gracilaria lemaneiformis increased with the extended incubation time and a considerable amount of NiO Nanoparticles were still present in the bodies of Gracilaria lemaneiformis. Exposure to NiO nanoparticles led to significant reductions of cell viability between 20 and 60% relative to controls. Elevated lipid peroxidation in Gracilaria lemaneiformis exposed to NiO nanoparticles compared to control and induced increases in MDA levels with incubation time. Significantly enhanced percent of mitochondrial depolarization in nanometer size compared to controls and NiO nanoparticles significantly elevated ROS levels more than three fold at the highest concentration. Taken together, these fmdings indicate that NiO nanoparticles exposure, especially for long periods of time, may exert negative impact on population of aquatic organisms and on food web dynamics in aquatic systems.