The use of nanoparticles in medicine, industrial, and other applications has triggered an interest in their potential. This book explores the use of nanoparticles related to their occurrence in the environment, their impact on biota in aquatic systems, application of new methodologies, and changes associated with new global scenarios. The book also covers the bioaccumulation and internalization of nanoparticles as key aspects to assess their uptake and discusses the methodologies for testing ENPs ecotoxicity at different trophic levels.