SEASONAL DYNAMICS OF BIOMASS AND NUTRIENT CONTENT IN THE INTERTIDAL SEAGRASS ZOSTERA-NOLTII HORNEM FROM PALMONES RIVER ESTUARY, SPAIN

The seasonal dynamics of above- and belowground biomass of Zostera nol tii Hornem. were studied in a permanent quadrat in the Palmones River estuary, southern Spain (36-degrees 11' N, 5-degrees 27' W) from Febru ary 1988 to February 1990. Temporal changes in nitrogen, carbon, diffe rent phosphorus fractions (soluble reactive phosphorus, total soluble phosphorus, particulate phosphorus and total phosphorus) and nutrient ratios (C/N, N/P and C/P), were also investigated in the same populati on from January 1989 to January 1990. Biomass of above- and belowgroun d structures showed a unimodal seasonal pattern with maxima in summer (180-200 g DW (dry weight)) m-2 and 70-75 g DW m-2 respectively) and m inima in winter (30-50 g DW m-2 and 25-30 g DW m-2). Internal concentr ations of carbon, nitrogen and phosphorus showed seasonal changes, wit h minima for nitrogen (3.0% for shoots and 1.2% for underground parts) and total phosphorus (0.45% for underground parts) in summer. Shoots and underground parts of Z. noltii contained maximum amounts of nitrog en (5.9 g m-2 and 2.1 g m-2, respectively), phosphorus (1.7 g m-2 and 0.6 g m-2) and carbon (66.9 g m-2 and 27.8 g m-2) in August. The annua l flux of nutrients from Z. noltii to the detritus compartment has bee n estimated to be about 14.6 g N, 4.1 g P and 155.3 g C m-2 of sedimen t surface.