Naslov
Distribution of dissolved and particulate carbohydrates in the northern Adriatic during the 1997 mucilage event

Autori
Tepić, Nataša ; Terzić, Senka ; Ahel, Marijan

Izvornik
Periodicum biologorum (0031-5362) 102 (2000), 2; 179-187

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

Ključne riječi
carbohydrates; photosynthetic pigments; mucilage; northern Adriatic; freshwater discharges; phytoplankton; diatoms

Sažetak
Background and purpose: Hypertrophic formation of gelatinous aggregates in the northern Adriatic occurred several times in the past two decades. It was shown that carbohydrates represent the major organic constituents of the northern Adriatic mucilage. The aim of this study was to investigate the distribution of carbohydrates during the 1997 mucilage event with a special emphasis on the partitioning between dissolved and particulate carbohydrates and the role of phytoplankton composition. Materials and methods: Seawater samples were collected during the summer 1997 in the central part of the northern Adriatic (transect Rovinj-Po River mouth). Carbohydrates were determined spectrophotometrically, using MBTH method, while photosynthetic pigments were determined by reversed-phase high-performance liquid chromatography. Results: The concentration of carbohydrates in the water column of the northern Adriatic during summer 1997 showed a pronounced spatial and temporal variability. The concentration of the total (dissolved+particulate) CHO varied in a rather wide range from 110 to 1050 microgC/l. Enhanced concentration was observed in the low salinity layer with maximum values found at the most western part of the basin, which was under the direct influence of unusually high Po River discharges during the early summer 1997. The spatial variability of particulate carbohydrates in the low salinity layer was closely correlated with the distribution of phytoplankton biomass. However, the distribution of dissolved carbohydrates revealed a more complex pattern. An increasing ratio between dissolved and particulate CHO along the eutrophic gradient Po River mouth- Rovinj suggested a gradual transformation of particulate into dissolved CHO. The analyses of biomarker pigments showed that diatoms and primnesiophytes were the main phytoplankton groups. The diatoms clearly dominated in the western part of the basin and represented the strongly predominant component of the bloom formed in the low salinity layer. Conclusion: The concentration of carbohydrates in the northern Adriatic was significantly enhanced during the 1997 mucilage event as compared to a summer with no mucilage formation by a factor of 2. The main source of carbohydrates was an intensive diatom bloom in the surface low salinity layer. However, distribution of dissolved carbohydrates, which represented the largest percentage of the total carbohydrates, was not well-correlated with the distribution of phytoplankton biomass. This suggested that the mechanisms, which govern partitioning of CHO between particulate and dissolved phases, such as phytoplankton exudation and cell lysis, as well as formation of (macro)aggregates, had a strong impact on spatial and temporal distribution of CHO.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA