Phaeocystis (Haptophyceae) has its special characteristics in physiology, biochemistry, and ecology, and is recognized as a group of worldwide harmful and toxic algae. It has a heterogenic life history involving sexual reproduction between single cells and colonies. The single cells have three types, i.e., non-flagellate cell, macrozoospore, and microzoospore. The transformation between single cells and colonies is affected by nutrients, light, solid matrix, and water body disturbance, etc. The tiny body size and the polymorphic forms cause many flaws in the morphology-based taxonomy of Phaeocystis. The application of molecular marker technology promotes the classification and phylogenetics of Phaeocystis greatly. The molecular markers for Phaeocystis classification and phylogenetics mainly include both nuclear and chloroplast genes. The phylogeny based on 18S rDNA suggests that Phaeocystis originates as a warm-water species with a global distribution. P. jahnii and P. cordata are diverged at earlier time, and the cold-water species isolated from warm-water ancestors may be diverged sixty million years ago. A total of seven geographical strains of Phaeocystis in China coasts have been recorded, but the study progress of their origin and spreading is still slow. This paper reviewed the taxonomy, life history, and phylogeny of Phaeocystis, and its origin, distribution, and spreading pattern in China. The future study on the taxonomy and phylogenetics of Phaeocystis was prospected.
In order to understand the potential of algal blooms, surface sediments were collected from 12 stations in the Changjiang River estuary with longitude from 122 degrees to 123.5 degrees E and latitude from 29 degrees to 32 degrees N from April to May 2002 to investigate the distribution of dinoflagellate resting cysts, 29 different cyst morphotypes representing 19 genera and 6 groups were identified. Among them, there were 11 autotrophic species and 18 heterotrophic ones. The number of species observed in each sample was low, and varied from 10 to 21. Cyst concentrations varied from 11.7 to 587 cysts per gram dry weight. Cyst concentrations and species diversity were higher in offshore areas, and increased from the west to the east, and from the north to the south within the studied area. Cysts of Alexandrium distributed widely in the Changjiang River estuary, with the maximum concentration of 40.4 cysts per gram dry weight. Cysts of harmful algal bloom causative species such as Alexandrium, Gymnodinium catenatum, Lingulodinium polyedra, Scrippsiellla trochoidea, Polykrikos kofoidii and P. schwartzii were also observed in this survey.
Eight species of the dinoflagellate genus Prorocen trum collected in April-May every year during 1998-2000 from Daya Bay, Guangdong, China, are identified and described. They are P. sigmoides, P. micans, P. tries tinum, P. dentatum, P. minimum, P. balticum, P. mexicanum, and an unknown species. All of them can cause red tide except the unknown one. P. minimum and P. mexicanum are susp ected of being toxic.
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