Importance of elongation and organogenesis on the rhizome length of Zostera marina in an individual-based simulation model

Abstract

The aim of this study was to assess the relative importance of phytomer organogenesis, mortality, and elongation rates on the rhizome length of Eelgrass (Zostera marina). Rhizome length has both a discrete and a continuous component, which are the number of internodes and their lengths, respectively. We hypothesize that rhizome length would be more correlated with elongation rates than either phytomer organogenesis or mortality. An individual-based model was used to simulate the growth of Z. marina individuals in the Punta Banda estuary in Baja California, a low-latitude Eelgrass population. Individuals of the model were composed of a rhizome and lateral branches, both of which were composed of phytomers. The individuals changed by presenting horizontal growth, clonal reproduction, aging, and age-related mortality. Some growth rates were modeled with respect to environmental conditions. The model was validated by comparing the rhizome length of simulated and observed plants. A sensitivity analysis suggested that simulated rhizome length is most correlated to elongation rates, which are mainly affected by water temperature and irradiance.