Seasonal Variation in Growth, Morphology, and Reproduction of Eelgrass Zostera marina on the Eastern Coast of the Shandong Peninsula, China

Abstract

Seasonal dynamics of Zostera marina were monitored monthly in Swan Lake of Shandong Peninsula, China, by examining plant density, morphology, weight, and environmental factors from February 2009 to January 2010. The greatest values for shoot size and weight were obtained in summer and the smallest values in winter and early spring. Reproductive shoots appeared in late March and developed into fruits in mid-June. Fruits were fully developed into mature seeds in mid-July. Reproductive shoot size and weight exhibited clear seasonal patterns with maximum values in May for leaf length, inflorescence length, and leaf width and in June for shoot length and shoot weight. The density of reproductive shoots ranged from 4 to 40 shoots m-2 with an average of 22.4 ± 12.8 shoots m-2 (mean ± 95% confidence interval) in July 2009. The average number of spathes per reproductive shoot was 18.9 ± 3.3, with 7.8 ± 0.7 seeds per spathe, and the mean seed dry weight was 3.2 ± 0.4 mg. Seasonal variations in shoot density and aboveground tissue dimensions correlated positively with water temperature. This study presents the first quantitative data on the seasonal dynamics of Z. marina in China.