Statistical inferences about the mucilage events in the Adriatic Sea, with special reference to recurrence patterns and claimed relationship to sun activity cycles

The secular hazard rate of mucilage events in the Northern Adriatic Sea appears to have remained constant over the last 120 years. The recurrence pattern can be described by either the exponential or the more general Weibull distribution model. There is a 50% probability that the next arrival of a mucilage event lies within a time period of 4–5 years, and a 90% probability for a mucilage event to return within 13–14 years or less. However, most events will be of local importance only and less severe than the 1988/1991 events. No statistically significant relationship between mucilage events and the 11-year sun activity cycles could be established. Increasing eutrophication and pollution do not appear to have a direct bearing on mucilage recurrence.