Nutritional evaluation of green macroalgae, Ulva sp. and related water nutrients in the Southern Mediterranean Sea coast, Alexandria shore, Egypt

Abstract

Protein, carbohydrate, lipid, ash, chlorophyll (a; b; c and total), organic carbon and moisture contents of the macroalgae Ulva sp. (Chlorophyta) were studied in corresponding to the water nutrient concentrations in different sites and seasonal variations over one year, 2012. The water and macroalgae samples were collected monthly from rocky and sandy sites, Ras Al-Tin (site A) and El-Muntazah (Site B) along 18.6 Km distance of Alexandria shore, Egypt. The results showed that the studied areas are rich in nutritive elements at high concentrations. As the chemical analysis showed that Ulva sp. powder was characterized by a high contents of protein (20.7-27.6% DW), lipid (8.7-15.75% DW), carbohydrates (42.31-51.37% DW) and moderate ash content (15.32-20.53% DW), with the peaks of lipid and minerals contents in winter, of carbohydrates contents in spring, of organic carbon contents in summer and of protein and phosphorus contents in autumn. The high nutrients content of Ulva sp. confirms the high nutrient storage capacity of Ulva in this area, indicating that, on one hand, it could be used as biofilters in the aquaculture systems and for bioremediation purpose. On the other hand, the proximate composition nominates Ulva to be exploited as a good food and energy resource for human; animals and fish. Also, it could be used in several industries such cosmetics industries and biofuel production, because of high carbohydrate content. Remarkable seasonal variations were recorded in the contents of the studied parameters in the Ulva samples. The N:P and C:P ratios indicated that these algae at the studied areas may experience phosphorus limitation in particular seasons during the annual cycle. The results showed also that Ulva nutrients content corresponded with the water nutrients concentrations, indicating that the Ulva sp. is an accurate and reliable indicator for pollution. Significant positive correlations were noticed between, carbon-nitrogen