Red Tides and Their Environmental Impacts in WESTPAC Area

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Cooperative field surveys on distribution of harmful plankton, fish and shell-fish and occurrence of poisoning were conducted to clarify the blooming and expansion mechanisms of the harmful plankton in Guatemala and Asian countries. In July 1995, a scientific meeting was held with scientists of these countries to develop and standardize technique.At Puerto Quezales of the Pacific coast of Guatemala, a dense bloom of the harmful dinoflagellate, Cochlodinium polykrikoides, was found. Plankton and cyst of the toxic strain of Pyrodnium bahamense were found in the Pacific coast, whereas those of possibly non-toxic strain in the Atlantic coast. They differ in their shape, but physiologically similar in growing slowly in enriched sea-water medium, requiring soil-extract.In eastern Indonesia, P.bahamense was found to make blooms at Kao Bay of Halmahera Island and Ambon Bay of Ambon Island. Resting cysts of the species were detected in both bays. The bays were near to Papua New Guinea, where P.bahamense bloomed for the first time in Asian waters. The finding of the species in the eastern Indonesia is important to clarify spreading route of the species, and continuous survey in wider area is thought to be necessary. In western Indonesia P.bahamense was found in Jakarta Bay and Bangka Island.At shrimp ponds in Indonesia and Thailand, the toxic dinoflagellate, Alexandrium minutum, was found to bloom and kill shrimps. But mechanism of the mass mortality has not been clarified yet.Along Malaysian coast of Malacca Strait, two toxic dinoflagellates, Gymnodinium catenatum and Alexandrium tamiy av anichii bloomed and might cause PSP poisoning occurred in 1993.In Philippijnes P.bahamense recurred for more than ten years with PSP cases of more than 2000 patients including 170 fatal ones. Accumulation of DSP toxin produced by Dinophysis in shellfish was confirmed for the first time in tropical countries.