| For the last few decades, harmful algal blooms have given a large economic loss to fisheries industry and serious poisoning problem to public health. The main causative organisms of these blooms are dinoflagellates. The study on modern dinoflagellate cysts as well as planktonic cells has been strongly recommended for understanding the mechanism implicated in the recurrence and geographic expansion of the harmful dinoflagellate blooms. Thirty cyst types capable of seeding plankton dinoflagellate populations have been identified in 11 stations along China Coast. The most common cyst was Scrippsiela trochoidea. These cysts belonged to the orders of Gonyaulacales, Gymnodiniales and Peridiniales. Two types of cysts recorded belonged to the potentially toxic genera of Alxandrium tamarense and Gymnodinium catenatum. The survey provided useful information on dinoflagellate species distribution along the China Coast. To assess the diversity and seasonality of dinoflagellate cyst production, surface sediment and trap samples were studied in the Bay of Daya (South China Sea). A total of 28 different cyst morphotypes were recorded. At the four stations, sediment assemblages were dominated by calcareous Peridiniales (43%-58%). The sediment trap sampling carried out fourteen months, revealed high production rates (up to 8*1 06/m2.d) in summer. Species-specific production patterns were observed: some species formed cyst over several months, others in restricted periods of the year. A coupling between the trap material and surface water plankton was observed for Scripsiela trochoidea. This sampling approach allowed the detection of some species never recorded before in the gulf. |
