Spatio-temporal variability of phytoplankton assemblages and its controlling factors in spring and summer in the Subei Shoal of Yellow Sea, China

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×103to 269.78×103cell/L with an average of 41.80×103cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×103cell/L with the range of 1.78×103to 574.96×103cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO4-Si(DIN/SiO4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.