hrvatski

Raspodjela ugljikohidrata u estuariju rijeke Krke

Particulate (PTCHO) and dissolved carbohydrates (DTCHO) were determined in the Krka estuary in order to determine their seasonal and spatial distribution patterns. The measurements were performed on samples collected on 4 stations, characterised by different hydrographic characteristics and exposure to anthropogenic inputs. Special attention was paid to the features of vertical and longitudinal distribution of carbohydrates in the highly stratified water column as well as to longitudinal distribution in characteristic water layers (brakish and marine). The results showed that the dominant percentage of carbohydrates was present in the dissolved fraction, which is especially pronounced in the marine layer (90-98 %), characterised by rather low phytoplankton biomass. Levels and percentage of particulate carbohydrates were considerably higher in the brackish layer, which is a consequence of enhanced phytoplankton biomass in that layer, and the maximum was observed in the eutrophic area of Šibenik Harbour. The maximum concentration of dissolved carbohydrates was also determined in the Šibenik Harbour and reached in July rather high value of 990 μ g C/l. It was observed that an accumulation of carbohydrates may occur at the halocline, which is mainly due to the enhanced concentrations of particulate carbohydrates, while the vertical profiles of dissolved carbohydrates varied in different seasons. The concentration of carbohydrates in the lower estuary reached enhanced values of the total carbohydrates similar to those observed in the northern Adriatic. However, as opposed to an intensive mucilage event in the northern Adriatic, formation of macroaggregates in the Krka estuary was not observed, most probably due to the rather low residence time of the brackish layer in the lower, eutrophic part of the estuary.

ugljikohidrati; rijeka Krka; estuarij

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