RELATING NUTRIENT RATIOS TO MUCILAGE EVENTS IN NORTHERN ADRIATIC

The north western part of the northern Adriatic exhibits eutrophic to mesotrophic characteristics with recurrent algal blooms and quite unpredictable mucilage events. To contribute to the understanding of the mucilage events in the northern Adriatic, a machine learning algorithm for induction of regression trees was applied to a data set comprising physical and chemical parameters, measured at six stations on the profile from the Po River delta (Italy) to Rovinj on the western Istrian coast (Croatia). A model describing the connection between the TIN/PO sub(4)ratio, considered as a necessary factor and sometimes even a trigger for mucilage events, and the environmental conditions in northern Adriatic was elaborated. The model for TIN/PO sub(4) ratio confirmed the assumption that the mucilage events are connected with the changes of this ratio in the system. This indicates that at certain levels of P limitation (TIN/PO sub(4) signal indicate) mucilage event frequency increases. The model also reveals which triggers are responsible (salinity and temperature) for the changes of the TIN/PO sub(4) ratio as well as their threshold values. As contrasted to to the TIN/PO sub(4) ratio, the mucilage events could not be attributed to the TIN/SiO sub(4) ratio