Phenology of Posidonia Oceanica (Linneaus) Delile in the West Coast of Algeria

The Posidonia oceanica seagrass in the western coast of Algeria on the subject of annual monitoring from November 2008 to November 2009.Two sites are selected and each are represented by a station located 10meters deep. The first is Cap Carbon which is polluted site subject to various major releases, and the second one is Ain Franin considered as a reference site relatively far from sources of pollution other than pollution considered sporadic during the summer where there is a rare attendance of holidaymakers. A study of the phenology of Posidonia oceanica meadows, on the leaf biometry, the coefficient "A" and the surface shows that these parameters are strongly influenced by seasonal factors and not by the depth as our samples were made at same depth.