With climate change and ocean acidification of the seas, more alien species are spreading in our seas. The green macroalgae, Caulerpa cylindracea, is considered an invasive species native from Australia that has rapidly spread across the Mediterranean since 1926. C. cylindracea colonises a variety of substrata, and its dominating presence has been found to alter indigenous flora and fauna biodiversity. This algal species has been a key invasive species in the NE Mediterranean and appeared in the Aegean Sea since late 1990’s. Its invasive success throughout this region is due to the algae’s extensive morphological plasticity, which as a result has spread from very shallow to very deep waters, and in a wide variety of habitats and conditions.

