Mucilage appearance in the Adriatic Sea during summer 2024

Here we report a very intense “mare sporco” event in the Northern Adriatic Sea region, which began in Croatia in June and lasted three months, impacting the Emilia-Romagna and Marche coasts and extending as far south as Apulia. We describe the event's progression, from mucilage dominated by Gonyaulax fragilis, to small diatoms, and finally bacteria, forming various shapes of marine snow and mucus aggregates. While these blooms are non-toxic, they have significant negative impact on the region's summer tourist industry.