Synthèse des connaissances sur les facteurs pouvant influencer le développement des blooms de dinoflagellés toxiques. Traitement mathématique des données hydrologiques acquises en baie de Vilaine en 1984 et 1985.

In this study, on one side, we have made a synthesis of the knowledge about the factors which could contribute to toxic or not dinoflagellates blooms. On the other side, we have analysed hydrological datas obtained from Vilaine bay in 1984 and 1985, by mean of two mathematical tools : 1 - The multiple linear regression; 2 - The clustering method by hierarchic classification. The first one uses an equation which aims to describe a biological phenomenon like phytoplankton blooms. The second one establishes the similarity degree between the plottings and must come to the characterization of groups of affinity stations in Vilaine bay. Among the partitions of some stations the more often found, these ones from the close extern estuary correspond to the maximum densities in Dinophysis, during the period from may to july.