Abstract
Data on nutrient contents of 27 seagrass species at 30 locations were compiled from the literature. Mean concentrations of carbon, nitrogen and phosphorus in seagrass leaves were 33.6, 1.92, and 0.23 dry wt, respectively. The median C:N:P ratio was 474:24:1, which represents a C:P ratio more than 4 times, and a N:P ratio more than 1.5 times that of oceanic seston. These ratios are, however, less than those previously reported for marine macrophytes (550:30:1) by Atkinson & Smith (1984). Nitrogen and phosphorus variability within species was large, but carbon contents exhibited little variability. Accordingly, carbon:nutrient (N and P) ratios were inversely related to changes in nutrient content, and the rate of change in C:N and C:P ratios with increasing nitrogen or phosphorus content in plant tissues should shift from high to small as nutrient supply meets the plant's demands. The median nitrogen and phosphorus contents reported here (1.8% N and 0.20% P as % DW) correctly discriminated between seagrass stands that did or did not respond to nutrient enrichment, thus offering a useful reference for comparisons of seagrass nutrient contents.