Climate-driven expansion of toxic ciguatera-causing dinoflagellates: emerging toxicological risks in Korean coastal waters

Abstract Background Climate-driven environmental changes are reshaping the distribution of marine harmful algal blooms, with several subtropical benthic harmful algal bloom (BHAB) dinoflagellates increasingly reported from warm-temperate coastal ecosystems. Among them, ciguatera-causing dinoflagellates have attracted increasing attention because of their potential impacts on seafood safety, fisheries, and public health. Their occurrence beyond traditionally recognized tropical and subtropical ranges presents an emerging challenge for coastal ecosystem management. Objective This review synthesizes current knowledge on the ecology, distribution, toxicological significance, and environmental factors associated with subtropical ciguatera-causing dinoflagellates, with particular emphasis on their occurrence in Korean coastal waters. We further identify current knowledge gaps and discuss future monitoring and management strategies to support ecological and toxicological risk assessment. Results Recent studies indicate that ocean warming, marine heatwaves, changing ocean circulation, and local habitat conditions may contribute to distributional changes in subtropical benthic dinoflagellates, including Gambierdiscus , Fukuyoa , Ostreopsis , Prorocentrum , Coolia , and Amphidinium . Monitoring surveys conducted by the authors between 2020 and 2025 repeatedly detected several of these genera around Jeju Island and along the southern and eastern coasts of Korea. Their occurrence in regions influenced by the Tsushima Warm Current is consistent with a potential contribution of warm-water transport, although a direct causal relationship has not been established. In addition, toxin characterization of Korean isolates remains limited, emphasizing the need for species- and strain-specific toxin analyses to better assess their potential toxicological risks. Conclusion The increasing occurrence of subtropical BHAB dinoflagellates in temperate coastal waters highlights the need for integrated long-term monitoring, species-level molecular identification, toxin characterization, and climate-based distribution modeling. Strengthening these approaches will improve early detection, ecological forecasting, and evidence-based management while supporting seafood safety under ongoing climate change.