The researchers studied the water quality and phytoplankton communities in Yeoja Bay, Korea from July to September 1998. They found that the water temperature ranged from 22.5℃ to 28.1℃ and salinity from 7.1‰ to 29.0‰. Nutrient concentrations were high in the inner Bay. Phytoplankton consisted of diatoms, dinoflagellates, and silicoflagellates. The highest phytoplankton concentration was in July, indicating a red tide. The main organisms causing the red tide were Thalassiosira weissflogii in the inner Bay and Chaetoceros decipiens and C. curvisetus in other parts of the Bay. The red tide in July was likely due to high nutrient levels and low salinity from surface runoff.