p. 181 - 203 OBSERVATIONS PHYSIOLOGIQUES ET BIOCHIMIQUES SUR L'ACTIVITE SEXUELLE CHEZ LES MOULES (MYTILUS GALLOPROVINCIALIS) Gabriela Dimoftache et Adrian Telembici Institut Roumain de Recherches Marines Constanta Abstract The paper presents the interrelations between the sexual activity of two types of mussels (rock and deep-water breeds) and the influence of certain abiotic and biotic environment parameters. The authors also investigated the dynamics of several groups of biochemical compounds in various period of the sexual cycle. The interdependence is stressed out which exists between the physiological activity and the biochemical composition within the annual sexual cycle of mussels.