Nutritional value of Cymodocea nodosa and Posidonia oceanica along the western Egyptian Mediterranean coast

The nutritional value of the two seagrasses Cymodocea nodosa and Posidonia oceanica and their potential use as fertilizers were evaluated based on the determination of biochemical content, major and trace element content in the leaves of the two species, occurring in five sites along the western Egyptian Mediterranean coast during summer (2006 and 2009). The total carbohydrates, total proteins and total lipids in C. nodosa were 47.22, 510.44 and 100.78 mg/g, respectively, and in P. oceanica 28.98, 607.50 and 40.50 mg/g, respectively. The calorific content was 4.03 K cal/g for C. nodosa and 3.93 K cal/g for P. oceanica. N%, P2O5% and K2O% and C:N ratio were 8.45%, 1.21%, 0.81% and 1.50:1 in C. nodosa, respectively, and 10.60%, 2.13%, 0.58% and 1.25:1 in P. oceanica, respectively. The concentrations of trace elements (Cu, Ni, Pb and Zn) in the two species were lower than in composts, while the major element concentrations in C. nodosa coincided with the typical concentrations in composts (P, 530.00; Na, 1044.44; Ca, 2470.00 mg/ 100 g), respectively, but higher in P. oceanica (P, 930.00; Na, 2765.00; Ca, 3890.00 mg/100 g), respectively.Cymodocea nodosa only can be potentially used as supplementary powdered organic fertilizer and/or additive compost.