Justification:
Posidonia oceanica is endemic to the Mediterranean, and is the most-widespread seagrass species in the region. It is an important habitat forming species and provides habitat for many species. There have been declines in the population of P. oceanica due to mechanical damage from trawling and boats, coastal development and eutrophication, with losses particularly observed in the western Mediterranean. The overall decline in the Mediterranean has been measured as approximately 10% over the last 100 years, which does not trigger any of the threatened categories, but further information is needed. P. oceanica is a very slow growing species and takes a long time to recolonize areas from where it has been removed, although there is some evidence that it has recolonized in some areas in the Mediterranean where it is protected. This species is listed as Least Concern.