Ecological provinces of spring phytoplankton in the Yellow Sea: species composition

Abstract

Phytoplanktonic ecological provinces of the Yellow Sea (31.20°–39.23°N, 121.00°–125.16°E) is derived in terms of species composition and hydrological factors (temperature and salinity). 173 samples were collected from 40 stations from April 28 to May 18, 2014, and a total of 185 phytoplanktonic algal species belonging to 81 genera of 7 phyla were identified by Utermohl method. Phytoplankton abundance in surface waters is concentrated in the west coast of Korean Peninsula and Korea Bay, and communities in those areas are mainly composed of diatoms and cyanobacteria with dominant species of Cylindrotheca closterium, Synechocystis pevalekii, Chroomonas acuta, Paralia sulcata, Thalassiosira pacifica and Karenia mikimotoi, etc. The first ten dominant species of the investigation area are analyzed by multidimensional scaling (MDS) and cluster analysis, then the Yellow Sea is divided into five provinces from Province I (P-I) to Province V (P-V). P-I includes the coastal areas near southern Liaodong Peninsula, with phytoplankton abundance of 35 420×103–36 163×103 cells/L and an average of 35 791×103 cells/L, and 99.84% of biomass is contributed by cyanobacteria. P-II is from Shandong Peninsula to Subei coastal area. Phytoplankton abundance is in a range of 2×103–48×103 cells/L with an average of 24×103 cells/L, and 63.69% of biomass is contributed by diatoms. P-III represents the Changjiang (Yangtze River) Diluted Water. Phytoplankton abundance is 10×103–37×103 cells/L with an average of 24×103 cells/L, and 73.14% of biomass is contributed by diatoms. P-IV represents the area affected by the Yellow Sea Warm Current. Phytoplankton abundance ranges from 6×103 to 82×103 cells/L with an average of 28×103 cells/L, and 64.17% of biomass is contributed by diatoms. P-V represents the cold water mass of northern Yellow Sea. Phytoplankton abundance is in a range of 41×103–8 912×103 cells/L with an average of 1 763×103 cells/L, and 89.96% of biomass is contributed by diatoms. Overall, structures of phytoplankton community in spring are quite heterogeneous in different provinces. Canonical correspondence analysis (CCA) result illustrates the relationship between dominant species and environmental factors, and demonstrates that the main environmental factors that affect phytoplankton distribution are nitrate, temperature and salinity.