Chair: Victoria Cole

Jun Sun (1)

¹ College of Marine and Environmental Science, Tianjin University of Science and Technology, Tianjin, 300457, China

Background
Living coccolithophores are very important marine phytoplankton functional group, playing crucial role in the marine carbon cycle. Recently studies suggested that their calcification process is susceptible to global climate change, especially ocean acidification.

Methods
We investigated the morphology, taxonomy, diversity and distribution of living coccolithophores in the China Sea Waters the first time. Samples were collected from a series of comprehensive invesigations including hydrology, geology, chemistry and biology in the Bohai Sea, Yellow Sea, East China Sea and South China Sea over years.

Findings
97 species were recorded, belonging to 4 orders, 11 families, and 44 genera. Genus Syracosphaera (20 species observed) presented the highest species-richness in the CSW. The overall coccoliphore abundance in the research areas ranged from 3 to 20 cells/ml. The dominant coccoliphore species were Gephyrocapsa oceanica, Emiliania huxleyi, Helicosphaera carteri, and Algirosphaera robusta, in the order of species abundance. The total coccoliphore abundance was highest in the East China Sea, followed by the South China Sea, Yellow Sea, Northern Yellow Sea and Bohai Sea. Seasonally, the coccoliphore were most abundant in autumn, followed by spring, winter and summer. Temperature and nitrate concentration may be the major environmental factors controlling the distribution and species composition of coccoliphores in the studying areas based on canonical correspondence analysis.

Conclusions
These findings provide information on the contribution of coccolithophores to the biological carbon pump in the China Seas and the controlling environmental factors on their distribution, and thus help to understand how the natural coccolithophore community will respond to the global climate change in the China Sea Waters.