p. 27 - 57 PARTICULARITES DES PHENOMENES DE "FLORAISON" Pia-Elena Mihnea et Elvira Cuingioglu Institut Roumain de Recherches Marines Constanta Abstract Some of the special conditions implied in the blooms phenomena are presented. Information on physical, chemical and biological conditions throughout 1975-1982, along the Romanian marine inshore waters are used. A comparison between the present state of phyto- planktonic community and the state that had existed twenty years ago, was done. The blooms of the most common species, the development of this phenomena, its dependence by physical and chemical factors, are discussed. In high eutrophicated waters a stronger dependence of phytoplanktonic blooms by physical than common chemical factors (P-PO4, N-NO3)seemed to be obviously.