The present contribution revealed that macroalgae can be successfully transported inside ballast tanks.
Since no thallus fragments were found, algal growth has to be related to the presence of microscopic forms able to survive and germinate.
It is remarkable that in 90 litres of water analysed it was possible to identify 15 taxa, especially in respect to the water on board (thousands of tons).
Almost all individuals grew from Mediterranean water samples and belong to the ubiquitous genus Ulva, common throughout the world in marine and estuarine habitats.
The allochtonous species was found in Port Said ballast water samples. As the high number of entries passing through Port Said, this area can be regarded as hot spot for the dispersion of non indigenous species.