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Abstract

Temporal changes in biomass, rate of photosynthetic activity and chemical composition of the seagrass Cymodocea nodosa (Ucr.) Asch., under the influence of various environmental factors, were followed in the Faborsa Bay, Northern Adriatic. Throughout the year the estimated average 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-September) and clear minima in winter. Net oxygen production was closely related to biomass, leaf length, chlorophyll concentration, water temperature and incident light intensity. No clear seasonality was observed in the chemical composition (protein, fats, total phosphorus) of C. nodosa. 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 nitrogen in leaves, and 5-17% for protein, 0.9-3.2% for fat, 0.1-0.6% for phosphorus and 0.9-2.8 for nitrogen in roots.

Effects of the Invasion of Caulerpa cylindracea in a Cymodocea nodosa Meadow in the Northern Adriatic Sea

“…The presence of C. cylindracea in the meadow did not affect the shoot density and the above-ground biomass of C. nodosa throughout the study period. Invaded meadow of C. nodosa showed consistent seasonal fluctuations reaching the highest above-ground biomass in the summers of 2017 and 2018, the lowest in winter, and exhibited exponential growth in spring as commonly observed for this species in monospecific meadows (Terrados and Ros, 1992;Zavodnik et al, 1998;Agostini et al, 2003). Likewise, the seasonal cycle of C. cylindracea in both settlements, with increasing biomass from summer to autumn, a drastic regression in winter and a renewed growth in spring occurred as reported for other temperate areas (Piazzi and Cinelli, 1999;Ceccherelli et al, 2000;Iveša and Devescovi, 2006;Blažina et al, 2009).…”