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

Abstract

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 directions. In the latitudinal trend, cysts are most abundant north of 34°N in the Yellow Sea, where Spiniferites bulloideus (Deflandre et Cookson) Sarjeant, and ellipsoidal Alexandrium cysts generally dominate. Cyst concentration 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 dinoflagellate cyst distribution in the Yellow Sea and northern East China Sea. The protoperidinioid/gonyaulacoid (P/G) ratio, which is considered to increase in proportion with increasing primary production, is of limited use in comparing with other areas because its value remains high in both high and lower primary production areas in our study.