Quelques aspects bioécologiques de Gamberdiscus toxicus, peridinien benthique responsable de la ciguareta à Tahiti

We have carried out on a fringing reef of Tahiti, catching periodically ciguateric fishes, a comparative dynamic survey of the population density of GAMBERDISCUS TOXICUS and some linked environmental factors, during a four year period. Half of the marine parameters, i.e. temperature, salinity, dissolved NO2, NO3, PO34, SiO2, have been systematically studied according to a weekly or a monthly rhythm ; the other parameters, i.e. pH, dissolved NH3, 02, C and B12 vitamin have been studied episodically. The local pluviometry for the two weeks preceeding the samplings has also been measured. The statis­tical analysis of the data did not allow us to observe any significant simple correlation between the physical or chemical parameters and the density of G, toxicus. These results suggest either the occurence of multiple correlation still to pount out or an indirect action of environmental factors, chiefly on other microorganisms of the benthic community, able to control G. toxicus population through trophic competition, antibiosis, synergic or antagonistic relations. From this point of view, the role of bacteria linked to cigua­teric biota seems important to elucidate.