Dinoflagellate cysts in recent sediments from Chinese coastal waters

Surface sediments were collected from 10 locations to study the distribution of dinoflagellate resting cysts in Chinese coastal waters from July 2000 to May 2002. Sixty-one cyst morphotypes representing 14 genera of three orders were identified in this survey. Seventeen cyst types were recorded for the first time from Chinese coasts. Rich cyst assemblages were recorded in closed or semi-closed nearshore harbors. Scrippsiella trochoidea was the most dominant and common cyst type in this survey, especially in sediments from Daya Bay, Dapeng Bay and Shenzhen Bay. However, Protoperidinium cysts were the most diversified group, predominating in Changjiang River Estuary, Zhujiang River Estuary, Zhelin bay and the Nanao Island area. Cyst concentrations in the top 2 cm surface sediments varied from 258 to 25,037 cysts.g(-1) dry weight sediment, and abundance was lower in Changjiang River Estuary and Zhujiang River Estuary. Cysts of two dinoflagellates capable of producing paralytic shellfish poisoning (PSP) -Alexandrium spp. and Gymnodinium catenatum- were detected almost in all locations. Furthermore, the ellipsoidal Alexandrium catenella and A. tamarense cyst complex was frequently observed in the surface sediment from Daya Bay, where high contents of PSP toxin and PSP episodes have been reported. Detailed descriptions and illustrations are provided of those cysts of newly recorded species, unidentified species, toxic species and dominant species.