Expansion of “Cochlo” red tides

Japan:
Several red tide cases of “Cochlo” occurred from spring to autumn in 2002, starting from Kyushu area and spreading to the north. Plotting each case on a map and analyzing relationship between location and date, it became obvious that there was a pattern which “Cochlo” expanded distribution by an ocean current form southwest to northeast.

Occurrence dates and locations of “Cochlo” along the Tsushima Current in 2002
（Please click a distribution map to get larger）

Korea:
There are two assumptions about origin cell of “Cochlo” red tide; 1) germinated cells from cysts in a bottom surface of coastal red tide occurrence area, and 2) vegetative cells occurring in the open sea in the south of Korea in June.
Red tide of “Cochlo” occurred at first at the southern coast of Korea, and gradually expanded its distribution to the eastern coast by water current. The following two pictures show the pattern in 2001 and 2002. Please click following pictures to start animation.