Toxins and Biologically Active Compounds from Microalgae: Volume 2: Biological Effects and Risk Management is devoted to the effects toxic microalgae and their poisonous products exert on living systems and how they may affect human activities. The most advanced information regarding the molecular mechanisms of action of major groups of toxins is presented, to frame for the description of toxic responses found in living systems exposed to microalgal toxins. Accounts of the recognized environmental effects of harmful algal blooms and the existing therapeutic applications of some toxins have been included. The picture is completed by the description of current initiatives to manage the risks posed by toxic microalgae, including strategies for the detoxification of contaminated seafood and the efforts to use most advanced informatic tools for the development of models for robust predictions regarding the appearance and the dynamics of harmful algal blooms. The complexity of risk management in the field is presented from a global perspective by highlighting major issues approached in world regions whose economic importance with regard to the production and commercialization of seafood is undeniable.