p. 117 - 137 CARACTERISTIQUES DU DEVELOPPMENT QUANTITATIF ET DE LA STRUCTURE DU PHYTOPLANCTON DE EAUX DU LITTORAL ROUMAIN PENDANT LA PERIODE 1983-1985 N.Bodeanu Institut Roumain de Recherches Marines Constanta Abstract Based on the researches carried out in the area from Sulina to Constanta, this work shows the characteristics of the quantitative development and the structure of the phytoplankton on the Romanian shore in the conditions of the eutrophication process between 1983 and 1985. On the background of its general feautures due to increasing sea eutrophication during the '70's, the evolution of phytoplankton has had some special characteristics for that period namely, a gradual reduction of the total quantities (according to a corresponding reduction of the nutrient stocks), a decrease of some blooming phenomena, a reduction of the main mass species(simultaneously with the opposite process of increasing of a less numerous group of mass species). The quantitative modifications of the populations in 1983-1985 and the lasser blooming of the algae belonging to Dinoflagellates group are also reflected by the reduction, year by year, of that group and the numerical and weight increase of the Diatoms group.