Harmful algal bloom causative collected from Hong Kong waters

Harmful algal blooms (HABs) have increased globally in recent years. In Hong Kong, a record algal bloom, caused by Gymnodinium mikimotoi and Gyrodinium sp. HK'98 (subsequently described as Karenia digitata) occurred in March and April 1998. Almost all fishes died in the affected cages, and the estimated economic loss caused by the HAB was HK$315000000 (equivalent to US $40000000). Most of the known toxic or harmful algal species are dinoflagellates. Some common dinoflagellate species such as Ceratium furca, Gonyaulax polygramma, Noctiluca scintillans, Heterocapsa triquetra, Prorocentrum minimum, Prorocentrum sigmoides, and Prorocentrum triestinum frequently bloom in Hong Kong waters. Others, such as Alexandrium catenella, Alexandrium tamarense, Gymnodinium mikimotoi, Gymnodinium cf. breve, Gymnodinium catenatum, Dinophysis caudata, Dinophysis acuminata, and Gambierdiscus toxicus bloom only occasionally, but their toxic effects or potentially toxic and harmful effects are very significant. Some important toxic and harmful, or potentially toxic and harmful dinoflagellate species are described. Among them, Gambierdiscus toxicus, a potential ciguatera fish poison producing species, and Gymnodinium cf. breve, a neurological shellfish poison producing species were new records from Hong Kong waters.