First record of Thalassiosira curviseriata Takano (Bacillariophyta) and its bloom in the East China Sea

A bloom caused by a diatom, Thalassiosira curviseriata Takano (Bacillariophyta), is recorded in the East China Sea for the first time in China during a red tide investigation cruise (MC2005-2) from 27 March to 12 April 2005. This bloom was developed with the competition of Chaetoceros debilis and Skeletonema spp. The highest cell density of T. curviseriata, which has reached 1.27×106 cells/dm³, was found in the surface and middle water layers of Stas ZD, ZB in the East China Sea (27.22°~29.48°N, 121.53°~122.98°E)in early spring in 2005. During the blooming period of T. curviseriata, the population with high cell density was found in the water area with temperature of 10~15℃ and salinity of 29.0~33.5. The percentage of the predominant species, T. curviseriata, has reached 95.8% of total diatom cells at one time in the middle water layer. The morphological characteristics of T. curviseriata, were observed with light microscope (LM) and transmission electronic microscope (TEM). The cells are 5.0~12.6 μm in diameter, connecting each other by mucilaginous thread to form spiral and curved chains. Description and LM and TEM images of T. curviseriata are presented. T. curviseriata is ecologically characterized by eurythermy and euryhalinity, and its population variation is affected mainly by silicate, the ratios of phosphorus to silicon and nitrogen to silicon.