Factors controlling the origin of Cochlodinium polykrikoides blooms along the Goheung coast, South Korea

We investigated the factors influencing the origin of Cochlodinium polykrikoides blooms along the Goheung coast (GH), and compared them to those along the Geoje (GJ) coast and in the East China Sea (ECS) which were used as reference sites. Stratification did not develop in GH during C. polykrikoides blooms, unlike that in GJ. The surface salinity during summer in ECS was equivalent to that of GH, whereas surface temperature and concentration of nutrients in ECS were markedly higher than those in GH or GJ. Thermohaline (or thermal) fronts appeared between the Korea Southern Coastal Water (KSCW) and the outer seawater during C. polykrikoides blooms. The result of numerical simulation models indicated that freshwater from the Yangtze River clearly affected KSCW. As a result, the origin of C. polykrikoides blooms in GH during summer could be attributed to the inflow of seawater from ECS with high water temperature and abundant nutrients.