Geographical distribution
Posidonia oceanica is an endemic plant of the Mediterranean, i.e. it is only present in this sea.
Posidonia oceanica in the Mediterranean :
Figure 2. Distribution of Posidonia Oceanica in the Mediterranean: the green dots correspond to the limits of the species' extension. Photo: IUCN
Posidonia oceanica meadows form a continuous belt along the Mediterranean coast (Fig.2), covering 20 to 50% of the seabed between 0 and 50m depth.
They extend practically all around the Mediterranean, from north to south, with the exception of the mouths of the major rivers: the Rhone and the Nile.
In the West, they also disappear a little before the Strait of Gibraltar and in the East, they are absent from the coasts of Egypt (east of the Nile delta), Palestine, Lebanon (Por, 1978) and Syria.
Finally, they are rare or absent in the far north of the Adriatic.
Posidonia oceanica in Tunisia :
Figure 3. Mapping of Posidonia oceanica meadows in Tunisia (Ben Mus-tapha and Hattour, 1992)
Posidonia oceanica meadows extend along the Tunisian coast from north to south (Fig.3).
They are very abundant in the Tabarka region in the north-west because of the quality of the water and the favourable environmental conditions.
However, they are becoming increasingly rare and degraded in the south, between Gafsa and Djerba, due to phosphate mining, intensive trawling and aquaculture.
Posidonia oceanica around the Kuriat Islands :
Figure 4. The main benthic biocenoses around the Kuriat islands of Sahar Chebaane