Thirty years of harmful algal bloom (HAB) research in Vietnam (1996–2026): achievements and future directions

Harmful algal bloom (HAB) research in Vietnam has developed substantially over the past three decades, evolving from bloom observations and morphology-based identification toward multidisciplinary studies integrating taxonomy, ecology, phycotoxins, molecular phylogenetics, remote sensing, modeling, and food-safety monitoring. International collaborative programs, particularly HABViet under the ENRECA/DANIDA framework, played an important role in strengthening national capacity in taxonomy, culture techniques, toxin research, monitoring, infrastructure, and postgraduate training. Major advances include multidisciplinary studies of Phaeocystis blooms in the south-central upwelling region; detection and characterization of paralytic shellfish toxins, domoic acid, and ciguatoxins; and long-term monitoring of harmful phytoplankton and marine biotoxins in shellfish-harvesting areas. More recently, integrative morphological, molecular, ecological, and toxicological approaches have substantially advanced knowledge of benthic harmful dinoflagellates, particularly Ostreopsis, Coolia, Prorocentrum, and Gambierdiscus. Freshwater HAB research has also expanded nationwide, with Microcystis–microcystins and Raphidiopsis–cylindrospermopsin emerging as the principal cyanobacterium–cyanotoxin systems investigated. Despite these achievements, major challenges remain, including uneven geographic coverage, fragmented long-term datasets, insufficient toxin characterization of local strains, and limited integration of environmental, food-safety, and public-health surveillance. Future priorities should emphasize coordinated long-term monitoring, expanded molecular and toxin reference databases, enhanced surveillance of freshwater and tropical reef ecosystems, and development of operational HAB and biotoxin early-warning systems.