The distribution pattern of soluble and particulate phosphorus within the seagrass Zostera noltti and, at the same time. the exchange of soluble reactive phosphorus (SRP) between leaves and the environment during short time periods, are studied. Two types of field experiments have been carried out: one, on plants under emersion stress, and the other on submerged plants. In submerged plants, SNRP and SRP concentrations are higher than in emersed ones. Concentrations of PP are higher in emersed lants. Maximum SRP concentration is generally found in the basal part of the leaf, reaching 94.8 ± 6.4 mmol P g-1 dry wt, in emersed and about 105.8 ± 5.4 mmol P g-1 dry wt, in submerged plants. Depending on incubation time and the emersed-submerged conditions, maximum SNRP concentrations are generally found in the leaf tip and in the belowground parts (root-rhizomes) in the submerged plants, and in the stem and in the root-rhizomes in the emersed ones, reaching up to 190.0 ± 26,5 mmol P g-1 dry wt in submergence and 123.3 ± 7.6 mmol P g-1 dry wt in emergence. Maximum PP concentrations are found in the rhizome, reaching up to 334.0 ± 25.0 mmol P g-1 dry wt, in emersed and up to 237.0 ± 15.0 mmol P g-1 dry wt in submerged plants. The phosphorus exchange dynamics between Leaves and the environment was also different in both experiments. Net balance becomes a leaf uptake (0.23 mmol P g-1 dry wt h-1) in emergence and a leaf release in submergence (0.05 mmol P g-1 dry wt h-1).