About twelve years of presence of the alien species Hypnea cornuta (Rhodophyta, Gigartinales) in the Mar Piccolo of Taranto (Ionian Sea, Southern Italy)

Populations of the alien seaweed Hypnea cornuta were followed on a twelve-years period in the Mar Piccolo of Taranto. On the 13 alien macrophytes identified in the basin since the eighties, it is the only established species that showed an invasive behaviour, even though without any clear negative effect on environment, human health or socio-economical activities.