Alexandrium, Black Sea, HAB, phycotoxins, phytoplankton, saxitoxin, toxic algae
Alexandrium cf. tamarense was recorded for the first time along the north-eastern coast of the Black Sea in July 2001. Since then, it has been observed annually between May and October. A maximum density of Alexandrium spp. of 9 000 cells l–1 was recorded during August 2004. Examination of the Black Sea Alexandrium spp. by scanning electron microscopy showed both A. tamarense and A. minutum to be present. Monitoring during 2000–2004 included the collection of mussel hepatopancreas samples and subsequent analysis for paralytic shellfish poisoning (PSP) toxins. A receptorbinding assay showed a maximum value of 14ìg STXdiHCl equivalents 100g–1 tissue to correspond to ambient concentrations of A. tamarense of 300 cells l–1. Analysis of the PSP toxins by liquid chromatography with fluorescence detection showed the presence of GTX2, GTX3 and GTX5 in mussel hepatopancreas extracts. PSP in humans has not been reported in the Black Sea region of Russia. Nevertheless, the presence of Alexandrium spp. and of PSP toxins in shellfish are compelling reasons for the introduction of phycotoxin control methods and monitoring in Russian waters.