The Faculty of Bioresources, Mie University, Kamihama, 1515, Tsu, Mie 514-8507, Japan
To clarify the structure and seasonal change of the Zostera marina population, the growth stage, population density, population height and LAI were measured with the stratified clip method. The three phases of growing, flowering and withering were distinguished with reference to the seasonal changes in the population structure. The sesvlts suggested that the major factors limiting the seasonal changes were temperature and intraspecific competition. It was thought that recruits of lateral shoots played a more important role in maintaining the perennial Zostera marina population than seeds and/or newly budding young shoots.