The outbreak of Chochlodinium sp.: the red tide maker in the coastal of Lampung Bay

Red tide is a common phenomenon and almost present every year in Lampung Bay. In 2012, the red tide in Lampung Bay showed a different characteristic compared to the previous ones. The research was conducted to analyze the characteristics of organisms causing the red tide and the factors affecting its occurrence. Assessments were done by identifying the dominant phytoplankton and observing the environmental condition using rapid assessment method. Seawater sampling was conducted in 15 stations in December 2012 to monitor the phytoplankton abundance, nutrient, and physical condition. The results showed that the organism dominating the phytoplankton population is Cochlodinium sp., comprising of 85.89% of the total phytoplankton suggesting it was the red tide organism in the Bay. The average abundance of this species in the stations was 2.0 × 10 4 cells/L. Choclodinium sp. was present agglomerated and distributed along the west coast of the bay. The highest concentration of the organism was found around the tip of the bay. The outbreaks of Choclodinium sp. were induced by the high concentration of nitrogen in the coastal water with N:P ratio of 35.5. Moreover, the physical condition of the coastal water strongly influenced the distribution and abundance of Cochlodinium sp. in the bay.