Naslov
Northern Adriatic mesocosm experiment Rovinj 2003: nutrient dynamics

Autori
Ivančić, Ingrid ; Degobbis, Danilo ; Pečar, Osvin ; Fuks, Dragica ; Manganelli, Maura ; Kraus, Romina ; Đakovac, Tamara ; Precali, Robert ; Scenati, Raffaele

Izvornik
Periodicum biologorum (0031-5362) 106 (2004), 1; 17-22

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
nutrients; N/P ratio; alkaline phosphatase; chlorophyll a; bacteria; mesocosm; Northern Adriatic

Sažetak
Background and Background and Purpose: Nutrient dynamics and influence on the plankton community of the northern Adriatic were studied during a month in 25 L mesocosms, enriched with nutrients in different ratios ("balanced", N/P=16 and "P-deficient", N/P=100), with the aim to contribute to understanding the production mechanism of microparticles, considered as precursors of the mucilage phenomenon. Materials and Methods: Seawater for the experiment was collected in May 2003 in a frontal zone between oligotrophic and eutrophic waters in the northern Adriatic, 20 Nm W off Rovinj (Istria). Seawater in 25 L bottles was enriched with nutrients and incubated floating on the sea surface. Analyses of nutrients and other relevant parameters were performed with methods widely used in oceanography. Results: Orthophosphate uptake occurred already in conditions of low phytoplankton biomass. Uptake of nitrate and orthosilicate was delayed for about a week in respect to orthophosphate, i.e. started only when phytoplankton biomass developed significantly. The bloom intensity was lower in "P-deficient" conditions, but not as low as predictable from the different orthophosphate enrichment in the two mesocosms. However, much higher alkaline phosphatase activity was induced in the "P-deficient" than in "nutrient balanced" mesocosm. Conclusions: In "P-deficient" mesocosm, orthophosphate was used more efficiently than in "nutrient balanced", due to rapid recycling by alkaline phosphatase. Furthermore, the N/P ratio of produced organic matter differed considerably between the two mesocosms, suggesting that phytoplankton in the northern Adriatic can grow over a broad range of N/P ratios.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Biologija, Temeljne medicinske znanosti

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