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Living coccolithophore assemblages collected at discrete depths (0–490 m) from eleven stations across the shelf and slope regions of the Yellow and East China Seas (YECS) during fall 2013 were analyzed using a scanning electron microscope. A total of 32 taxa were recorded, and the predominant taxa were Emiliania huxleyi , Gephyrocapsa spp., Syracosphaera spp. and Algirosphaera robusta . The body coccoliths of A. robusta exhibited an unusual morphology with incomplete hoods, which were recorded in nearly half of the samples and may represent a new variety. In addition, an agglutination relationship was observed between Gephyrocapsa coccoliths and the tintinnid Dictyocysta lepida in oligotrophic waters. Total coccolithophores reached a maximum cell abundance of 252 × 10 3 cells/l (on average 27.8 × 10 3 cells/l), with the contribution of Gephyrocapsa ericsonii , E. huxleyi and Gephyrocapsa oceanica accounting for 36.4%, 29.6% and 15.3%, respectively, of the total abundance. Coccolithophore assemblages in the YECS were a mixture of coastal, shelf and subtropical taxa, with the diversity decreasing in a radial direction from the Okinawa Trough to the inner shelves. Distinct deep-water flora existed in the Kuroshio slope waters (100–490 m), which was precisely reflected by the cluster analysis, illustrating very low percent similarity (48.1%) with the other groups. The occurrence of subtropical taxa in the coccolithophore assemblages can be used as benign warmer water signals. In the bottom turbid layers, the coccolithophore assemblages were largely composed of free coccoliths (84.3%), implying complex processes, such as cell death, resuspension and lateral advection, in the sandy and detrital waters. To clarify the relationship between the species distribution and ambient environments, a redundancy analysis (RDA) was applied to distinguish how much the variation in the taxon composition could be attributed to changes in the environmental conditions. Conclusively, salinity and temperature, which to some extent could reflect the physical properties of water stability and stratification, were key factors in driving the distribution patterns of living coccolithophores in the study areas. [ABSTRACT FROM AUTHOR]

Spring and winter distributions of living coccolithophores in the Yellow Sea were studied using a polarizing microscope based on two surveys in April 2010 and January 2011. Nine species were recorded, including Emiliania huxleyi and Gephyrocapsa oceanica as the predominant forms. The cell abundance of all coccolithophores in the spring was significantly higher than in the winter ( p<0.01), with means of 15 387 and 2470 cells l-1, respectively. Notably, we observed a habitat selection of coccolithophores in the southeastern Yellow Sea (32-35°N, 123-125°E). This habitat was characterized by sharp temperature gradients during both seasons caused by water exchange between the shelf waters and the Yellow Sea Warm Current. Moreover, the cell abundance, standing crop and estimated fluxes of coccolithophores were abnormally high compared to other regions. The habitat preference of coccolithophores in the Yellow Sea was directly related to the hydrodynamic conditions. The unfavorable light conditions caused by the intense convective mixing were responsible for the low biomass of coccolithophores during the winter. However, the increasing temperature influenced by the warm current, in combination with water column stability, triggered the spring bloom of coccolithophores in the southern Yellow Sea. [ABSTRACT FROM AUTHOR]