SEASONAL-VARIATIONS IN THE RATE OF PHOTOSYNTHETIC ACTIVITY AND CHEMICAL-COMPOSITION OF THE SEAGRASS CYMODOCEA-NODOSA (UCR.) ASCH

Temporal changes in biomass, rate of photosynthetic activity and chemi cal composition of the seagrass Cymodocea nodosa (Ucr.) Asch., under t he influence of various environmental factors, were followed in the Fa borsa Bay, Northern Adriatic. Throughout the year the estimated averag e biomass was about 130 g dry wt m(-2) with annual production of 80 g C m(-2). In general, leaf length, biomass and production showed clear seasonality, with maximum values during the summer period (July-Septem ber) and clear minima in winter. Net oxygen production was closely rel ated to biomass, leaf length, chlorophyll concentration, water tempera ture and incident light intensity. No clear seasonality was observed i n the chemical composition (protein, fats, total phosphorus) of C. nod osa. Over the annual cycle, the range of measured variables was 10-16% for protein, 1.7-3.1% for fat, 0.3-0.8% for phosphorus, 1.6-2.6 for n itrogen in leaves, and 5-17% for protein, 0.9-3.2% for fat, 0.1-0.6% f or phosphorus and 0.9-2.8 for nitrogen in roots.