engleski

Decrease of surface-active substances concentration during last decade in the northern Adriatic Sea

Surface-active substances (SAS) were studied monthly since 1998 in the eastern part of the northern Adriatic Sea. The SAS pool decreased in the last decade by 15. Comparing SAS data from the late 1990ies and late 2000ies it is observed that the production of biogenic SAS, as an indicator of phytoplankton activity, was both lower in surface waters and furthermore was shifted deeper in the water column. We deduce that this change was caused by a decrease in inflow from the Po River leading to a reduced nutrient supply to the basin. In addition we suggest the production of biogenic SAS by phytoplankton shifted to deeper water in response to the vertical distribution of nutrients which had been more derived from regenerative processes. The timing of the increase in the particulate SAS fraction, indicating blooming conditions, has shifted over the last decade from early spring to early/mid winter indicating earlier blooming. SAS are mainly present in the dissolved fraction and this fraction contributes on average more than 90% of the total SAS.

surface-active substances; northern Adriatic Sea

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