Seasonal variation in leaf age structure of the Eelgrass Zostera marina on the eastern coast of the Shandong Peninsula, China

Abstract

Many important processes for Seagrass ecology depend on leaf age. Through biweekly census, from April to November 2015, seasonal variation in leaf age structure of the Eelgrass Zostera marina L. was studied in Swan Lake of Shandong Peninsula, China by examining density, dimensions and biomass of shoots relative to leaf ages. In addition, we examined if variability in leaf age structure was related to water temperature and/or underwater irradiance. The leaf density, number of leaves per shoot, leaf area index, total leaf area per shoot and leaf biomass of young and old Z. marina leaves were far less than those of the mature leaves with percentages of >50% in all leaf ages. The leaf age structure of mature Z. marina leaves exhibited a clear seasonal variation with significant peaks in early July, which corresponded with the seasonal changes in shoot density and biomass of Z. marina. The results demonstrated that mature leaves would be a leading component in leaf age structure of Z. marina. Curve Estimation revealed that the seasonal variation in leaf age structure of Eelgrass was closely positively related to water temperature. The results provided data that could prove helpful in quantitative studies of leaf-age dependent aspects of Seagrass ecology.