Search

Living coccolithophores (LCs) are regarded as a group of calcifiers and play important roles in global carbon cycle. This study used microscopic observations of LCs in the western Pacific Ocean to investigate their community structure and biodiversity, especially to test whether local physical traits (mesoscale eddies) could explain their biogeographic distributions during autumn of 2017. The coccolithophore calcite inventory based on carbon-volume transformation was estimated in this study. A total of 28 taxa of coccospheres and 19 types of coccoliths were identified from 161 samples. Gephyrocapsa oceanica was the most predominant species in all the coccolithophore community, followed by Florisphaera profunda, Emiliania huxleyi, Umbilicosphaera sibogae, Gladiolithus flabellatus and Umbellosphaera tenuis. The abundance of coccospheres and coccoliths ranged from 0 to 26.8×103 cells/L and from 0 to 138.5×103 coccoliths/L, averaged at 4.2×103 cells/L and 10.9×103 coccoliths/L, respectively. This study indicated that coccolithophore community in the survey area can be clustered into four groups. Three ecological niches of coccolithophores were characterized by their vertical profiles and multivariate statistical analysis. Coccolithophore abundance and species composition were remarkably different among warm-eddy region, G. oceanica dominated warm-eddy region, while F. profunda dominated warm-eddy and none-eddy region. The average values of estimated particulate inorganic carbon, particulate organic carbon were 0.197 μg/L and 0.140 μg/L, respectively. The current field study widened the dataset of coccolithophores in western Pacific Ocean.

One strain of unicellular flagellated yellow-green algae was successfully isolated from the coastal area near Tianjin in the Bohai Sea in May 2015. The strain ranged from round to elongated in shape. Most of the cells possessed active motility, and some cells formed non-motile aggregation. Based on evidences from morphology, ultrastructure and molecular analysis, we identified the strain as Pavlova pinguis which belonged to Pavlovophyceae, Haptophyta. For Pavlovophyceae, only Pavlova viridis (Diacronema viridis) was reported in China seas prior to this study and it played an important role in aquaculture. This is the first record of Pavlova pinguis in Chinese waters.

The phytoplankton water samples were collected in two multidisciplinary investigations which were carried out during summer (June) and autumn (November to December) of 2011. Phytoplankton species composition and abundance data were accomplished by Utermohl method. The phytoplankton community was dominated by diatoms and dinoflagellates in the southern Yellow Sea (YS) in summer and autumn. In summer, Paralia sulcata and Prorocentrum dentatum were the predominated species, the cell abundance ranged from 0.074 to 107.733×103 cells/L with an average of 9.057×103 cells/L. Two phytoplankton high abundance appeared in northwest part of the survey area and the Changjiang River Estuary, respectively. In autumn, Par. sulcata became the predominant species, and the phytoplankton cell abundance ranged from 1.035×103 to 8.985×103 cells/L, the average was 3.263×103 cells/L. The phytoplankton abundance in surface layer presented the homogeneous distributions. Canonical Correspondence Analysis (CCA) method was applied for discovering the relationship between environmental factors and the common found phytoplankton species. The responses of phytoplankton to nutrients were varied between summer and autumn. The abundance of most predominant species, Par. sulcata was strongly correlated to temperature and salinity in autumn, but not the case in summer.