Gambierdiscus is a genus of large epibenthic dinoflagellates of interest as the causative agents of ciguatera poisoning. Little is known about their swimming behavior and how that affects sampling and monitoring efforts for enviromental populations. Pelagic dinoflagellates frequently exhibit diel vertical migration behaviors, but whether benthic dinoflagellates exhibit analogous diel migration (DM) patterns has not yet been established. The presence of DM might affect important sampling and monitoring efforts of cells like Gambierdiscus, as well as trophic toxin transfer models if systematic shifts in cell locations occur. In this work, we demonstrate a framework for observing the swimming behavior and diel patterns in the lateral movement of multiple species of Gambierdiscus in cultures, inferring their vertical movement off the surface, and show marked differences in the diel patterns exhibited between species. This differentiation in the timing of movements, when viewed in the light of varying toxin levels among species, may have implications on toxin monitoring from environmental samples. 本文は、ISSHAのHP（　リンク：https://issha.org/publications-resources/conference-proceedings/　）にて公開。 Ichiro Imai, Ryoji Matsushima, Satoshi Nagai, Goh Nishitani, Setsuko Sakamoto, Toshiyuki Suzuki (Eds.). 2023. Proceedings of the 20th International Conference on Harmful Algae, Hiroshima, Japan. International Society for the Study of Harmful Algae. 【21-24】 pp.