Abstract

Harmful algal blooms (HABs) cause severe socioecological, economic, food innocuity, and public health problems in countries where aquaculture, fisheries, and tourism share marine ecosystem goods and services. HABs will likely intensify with rising eutrophication, ocean warming, acidification and climatic atmospheric and oceanographic os-cillations (e.g., El Nin similar to o). During the Decade of Ocean Science for Sustainable Development (2021-2030), it is imperative to produce knowledge to predict HABs and mitigate their severe negative sustainability consequences. This review on coevolved symbiotic and antagonistic algae-bacteria interactions highlights the HAB holobiome, i.e., phycosphere-attached and free-living bacteria, as potential bioindicators of bloom onset and decline as they promote, inhibit or suppress algal growth. The reviewed literature led us to discuss (1) the conceptual issues and experimental approach required to generate and include the HAB holobiome data into monitoring schemes to evaluate the resulting predictive model, (2) the relevance of an integrated science-policy approach to articulate the holobiome knowledge among stakeholders, including policymakers, for the efficient use and adaptive management of ecosystem services, and 3) a way to translate, once validated, the holobiome-based predictive model into a widely adopted policy. In this sense, the ongoing Monitoring Algae in Chile project (MACH; www.mach-satreps.org/en/) provides a framework to articulate the holobiome science with policy to establish reliable forecast systems to minimize HAB impact on public health, aquaculture and fisheries activities. This Chilean-Japanese research collaboration builds on the lessons from the catastrophic HAB event on Chiloe ' Island (May 2016), where world-class salmon, mussel aquaculture, and arti-sanal fishers coexist.