Distribution of dinoflagellate cysts in surface sediments from the Yellow Sea and East China Sea

The distribution of dinoflagellate cysts in surface sediment samples of the Yellow Sea and East China Sea has been examined from 48 samples. Emphasis has been placed on ellipsoidal cysts of the genus Alexandrium. Results show two concurrent cyst distribution trends in latitudinal and longitudinal di rections. In the latitudinal trend, cysts are most abundant north of 34 deg reesN in the Yellow Sea, where Spiniferites bulloideus (Deflandre et Cookso n) Sarjeant, and ellipsoidal Alexandrium cysts generally dominate. Cyst con centration decreases towards both sides of the northern East China Sea in a longitudinal direction. Various factors such as cyst production, particle size of sediment and sedimentation rates may contribute to the dinoflagella te cyst distribution in the Yellow Sea and northern East China Sea. The pro toperidinioid/gonyaulacoid (P/G) ratio, which is considered to increase in proportion with increasing primary production, is of limited use in compari ng with other areas because its value remains high in both high and lower p rimary production areas in our study. (C) 2001 Elsevier Science B.V. All ri ghts reserved.