To investigate the historical record of Alexandriumspp. in southern coastal areas ofKorea, two sediment cores were collected from Gamak Bay and Yeoja Bay. Germination experi-ments revealed that the ellipsoidal Alexandriumcysts isolated from Gamak Bay and Yeoja Bayare morphologically identical to a toxic dinoflagellate A. tamarense. The ellipsoidal Alexandriumcysts in Yeoja Bay appeared from 30 to 32 cm depth upwards(ca. 1980s), and their concentrationincreased around 10 to 12 cm depth(mid-1990s). Similarly, cyst concentration in Gamak Bay alsoincreased from 40 to 44 cm depth(ca. 1990s). These results coincide with the reports of ParalyticShellfish Poisoning caused by A. tamarensein 1980s and 1990s along the southeast coast of Korea.

• Hyeon Ho Shin(Library of Marine Samples, Korea Institute of Ocean Science and Technology) Corresponding author