Updating of alien macroalgae in the Venice Lagoon, new introductions and cryptogenic species.

A revision of the number of NIS in the Italian coasts shows an alarming increase of alien macroalgae: from 35 taxa in 2012 to 52 taxa in 2014, out of which many are invasive, potentially invasive or punctual records, while others are cryptic species requiring further investigation. The Venice Lagoon is the Italian site with more reports accounting for 54% of the total NIS recorded in the Italian coasts and looks like a hotspot from which NIS can be exported in other environments. The decade characterized by higher number of new NIS records was 1991-2000 and the vector responsible of the major number of introductions was aquaculture (mollusc importation for shellfish culture and live seafood trade) followed by vessels.