Loss and gain of marine biodiversity in Mediterranean seawaters

The Mediterranean Sea is one of the most important biodiversity hotspots worldwide. The high biodiversity level of the basin is confirmed by the presence of about 17,000 marine species of which 20.2% are endemics. Amongst them, Posidonia oceanica (Linnaeus) Delile can form, in pristine coastal waters, large and extensive meadows, performing a pivotal role in endemic processes. However, the richness of marine biota is, actually, affected by some threats such as habitat loss, marine pollution, climate changes, eutrophication and the establishment of invasive alien species coming from the Indo-Pacific region through the pathway of Suez Canal. This trend could lead to a new kind of marine biodiversity influenced by the introduction of termophilic species altering the pattern of Mediterranean biota. Anyway, it is necessary a global approach, ensuring the better ecological conditions so to protect marine biodiversity in meditrranean seawaters.