Harmful algal blooms (HABs) have significant socio-cultural and economic negative impacts resulting from bans on finfish and shellfish collection and commercialization, restriction of tourism and leisure activities, as well as addi-tional costs related to human health and increased monitoring activities. Estimations of the economic impact of HABs have been mostly focused on sectors of society for which the financial losses are relatively more evident (e.g., fisher-ies, aquaculture, human health), with very few assessments so far taking into consideration their effects on coastal communities and/or ecosystem services. This chapter provides the first overview of the disruptive impact of HABs on the blue economy, with a particular focus on the application of science and technology advancements in their management and mitigation. For that, we present case studies of HABs in five different locations as examples of their effects on the different sectors of the blue economy. We also review main technological advancements in the last decades and current needs for a better understanding of HAB dynamics, improved taxonomy of causing organ-isms, toxin detection, monitoring, and forecasting. An evident gap in dealing with HABs in the frame of the blue economy is the inequity in the resources available for monitoring in the different areas of the world: while developed countries count on advanced (and even impressive) tools for monitoring and early warning (e.g., automated tools, oceanographic moored instruments, forecast models), efficient monitoring in most developing countries is still missing and, when performed, mainly focused on seafood products aimed for exportation. Basic research on HABs in these countries is also frequently deficient, with modeling capabilities for early warning virtually non-existent. Considering that many (truly) sustainable blue economy activities are developed precisely in vulnerable areas with low economic power, it the need for the development of affordable and sustainable technologies becomes critical, allowing for the efficient monitoring of HABs. This need is reinforced by the fact that some HAB-related health issues (ciguatera being the most emblematic among those) occur mostly in developing countries in the tropical and subtropical areas, which poses constraints against the implementation of sustainable fisheries, aquaculture, and tourism in these areas

International Workshop on the Application of Ocean Science and Technology for the Practice of Sustainable “Blue Economy” in Developing Countries, 8-9 November 2021