Invasione Mnemiopsis leidyi Invasion of Mnemiopsis leidyi Intotheblue.it
This video made on August 20, 2019 documents the invasion of Mnemiopsis leidyi in the waters of the coast between Livorno and Castiglioncello. This phenomenon is becoming increasingly frequent in recent years, and these days we are witnessing similar events in the Mediterranean Sea, for example in the Adriatic Sea.
Certainly the main cause is the current climate changes, especially global warming and tropicalization of the Mediterranean Sea. Its proliferation is an increasingly common event and is to be considered a real environmental damage, from the moment that in the Mediterranean this Ctenofora has no natural predators able to stop its spread.
Mnemiopsis leidyi is considered an alien species. The Sea Walnut (Mnemiopsis leidyi A. Agassiz, 1865) is a ctenophore belonging to the Bolinopsidae family. It is a species native to the Atlantic introduced with ballast water from tankers in the Black Sea, the Baltic and the Caspian. Over time it has also colonized other seas to reach the entire Mediterranean Sea.
Mnemiopsis has been included in the list of the 100 most invasive invasive species in the world.
The damage is due to his fertility and his zooplankton-based diet. It has been calculated, for example, that its presence is at the origin of the 80% decline in the zooplankton of the Caspian Sea. Strong repercussions on the environment and on the economy have had its introduction in the Black Sea. In other seas its impact has been important, even if minor, probably due to the presence of predators or other planctophagi. The harmfulness derives from the consequences of its development (it adapts very easily to new environments, withstanding wide temperature variations), since the decrease in zooplankton directly or indirectly reduces the local fish populations.