Benthic Diatoms from the Tidal Flat of Shanghai, China, during 2005 Summer
上海市滩涂夏季底栖硅藻初步研究

The species composition and ecological distribution of benthic diatoms were investigated in the tidal flat of Shanghai, China. Benthic samples were collected from 7 sites in August, 2005. Ninety-eight taxa including 31 genera and 10 families were identified. Navicula (15 taxa) was the most abundant followed by Nitzschia (10 taxa). The dominant species were Cyclotella meneghiniana, Gyrosigma spencerii, Surirella ovata and the common ones were Fragilaria capucina, Gyrosigma attenuatum, Naicula acceptata, etc.. The occasional species were Melosira italica, Coscinodiscus wittianus and Navicula pygmaea. Quantitative analysis showed that the total diatom cell density ranged from 7.0×106-28.5×106 cells m-2, with an average of 17.39×106 cells m-2. More diatoms were found at the convergence of runoff and seawater, and freshwater species were more abundant than saltwater ones, mainly because Yangtze River estuary waters are composed of various waters, into which freshwater brings many freshwater species.