The nutritional value and chemical changes in the lipid content of the green macroalgae, Ulva sp., were assayed in the present study. Ulva samples were collected from two stations, Ras Al-Tin (station A) and El-Muntazah (Station B) along
Alexandria shore on the Mediterranean Sea, in twelve sampling periods (from January to December 2012). Each three samples of each station were plotted to represent one season. The chemical characterization of the lipid fractions was
performed by gas liquid chromatography. The result showed that Ulva lipid content is relatively high (9.4±1.5 and 12.2±2.7%DW, at station A and B respectively) that can be explained by the higher pollution level at the station A. The fatty acids (FAs) of Ulva sp. lipidic extract mainly composed of palmitic, oleic and linoleic FAs. Saturated
fatty acids (SFAs) represented about 50% of the total FAs (TFAs). Monounsaturated
fatty acids (MUFAs) accounted for a high percent, 17.6-33.4% of TFAs.
Polyunsaturated fatty acids (PUFAs) existed in a high percent in Ulva extraction reaching a maximum in winter and spring at both stations, about 38.4 and 30.5% of TFAs at station A and B, respectively. The high percent of PUFA can be attributed to the correlation between the low temperature and the degree of unsaturation. Also, the long chain fatty acids (C16 and C18) constitute more than 82% of the TFAs, which are the main components for biofuel. The results indicate that Ulva has a good potential for its use in human and animal food and health maintenance as a rich source
of MUFAs and PUFA as well as in biodiesel production. Also, the wide ranges of the fatty acids indicate the possibility of manipulating the fatty acids profile through the cultivation conditions.