Further expansion of the alien seaweed Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procacini (Ulvophyceae, Bryopsidales) in the Eastern Mediterranean Sea

Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman and Procacini is a green alga of Australian origin recently reported as an alien species in the Mediterranean Sea, where it is known from SE Turkey, Sicily, Cyprus and Malta. In the current study we present additional records of this taxon, expanding its known distribution into the Eastern Mediterranean Sea, and provide additional records from Cyprus and the first records from Rhodes Island (Greece). Our specimens were identified through a combination of morphological and molecular methods involving sequencing of ITS and tufA. Locally, C. taxifolia var. distichophylla occurred in high abundances and dominated the benthic community, suggesting that has the potential to become a major pest in the Mediterranean. It was also observed over a very wide depth range, from the sea surface to at least 100 m depth, on a variety of natural soft and hard substrates as well as abandoned fishing nets, suggesting a broad environmental plasticity. One of the findings reported here constitutes the deepest record of an alien Caulerpa in the Mediterranean Sea, even though it remains to be demonstrated that it actually grows at this site and depth rather than being merely a drift specimen.