Environmental Studies on a Toxic Dinoflagellate Responsible for Ciguatera

Population assays and analyses of sea water were conducted simultaneously at various places of French Polynesia to investigate environmental factors affecting the distribution and population of Gambierdiscus toxicus. The population of the organism was low at Tahiti, Moorea and Bora Bora islands but was extremely high at the Gambier islands. Thus the ciguateric endemicity of the surveyed area was well explainable by the abundance of the organism. Nutrients such as the inorganic phosphorus, total phosphorus, nitrite, nitrate, silicate, iron, dissolved organic carbon, and vitamin B12 showed little correlation with the population of G. toxicus. The benthic community consisting of corals, macroalgae and benthic microalgae such as diatoms and dinoflagellates seemed to play an important role in regulating the population of the toxic dinoflagellate. © 1980, The Japanese Society of Fisheries Science. All rights reserved.