Invasive sea walnut species spreads through the Adriatic Sea

The invasive comb jelly Mnemiopsis leidyi, commonly known as the ‘sea walnut’, is spreading through the Adriatic Sea, potentially threatening local marine ecosystems. While the organism is harmless to humans and does not sting, its presence in large numbers has been noted along the Istrian coast.

Originally from the East Coast of North America, the species was introduced to the Black Sea in the 1980s and later detected in the Baltic Sea in 2006. Experts from the Institute of Oceanography and Fisheries in Split note that the species has been observed in significant quantities in the northern Adriatic since 2016, likely introduced via ballast water from ships.