Species Diversity and Eco-geographical Distribution of Dinoflagellate Cysts in the Bohai Sea, China
Yan Wang, Lin Huang, Haifeng Gu, Shuang Li, Shaoshan Li
Chin Bull Bot. 2012, 47(2):
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We collected 144 dinoflagellate cyst samples at 24 stations in the Bohai Sea in May and August 2008 to investigate species diversity and geographical distribution, as well as water eutrophication. We identified 32 dinoflagellate cyst species belonging to 6 groups, including 11 species of Protoperidinioids, 6 Gymnodinioids, 7 Gonyaulacoids, 5 Calcoidinellids, 2 Diplopsalids and 1 Tuberculodinioid. In the 17 autotrophic dinoflagellate cyst species, the dominant species are Scrippsiella trochoidea, and Polykrikos schwartzii and Protoperidinium conicum in the 15 heterotrophic dinoflagellate cyst species. Alexandrium tamarense, a species producing paralytic shellfish poisoning toxins, was found only at 3 stations. In general, the enriched heterotrophic dinoflagellate cyst species indicates relatively high eutrophication in the Bohai Sea. The predominance of S. trochoidea contributed substantially to the formation of harmful algal blooms in the studied area. We collected 10 cm vertical surface sediments from each sampling site and cut them into 3-cm-high sections representing the surface, middle and bottom layers. Species compositions were similar among the 3 layers and ranged from 5.58 to 7.29 in species numbers and from 58.82 to 103.57 cysts·g–1 dry weight in density. The mean biodiversity indexes in May in the surface, middle and bottom sediments were 1.69, 1.61 and 1.52 and in August 1.83, 1.89, and 1.60.