IMPACT OF PHOSPHORUS LOADINGS ON MACRO-ALGAL COMMUNITIES IN THE RED-SEA COAST OF EGYPT

This study was undertaken to investigate the impact of phosphorus loadings on the seasonal abundance and diversity of macro-algal communities at three sites of the Egyptian coastal region of the Red Sea. Sea-water analysis revealed no significant variations in the levels of dissolved inorganic carbon at these sites. Nitrate content was highest during the winter season especially at Ghardaqa. The localized phosphate pollution at the two other sites significantly increased the phosphate level in water which led to significant decreases in biomass of the macroalgae as compared to Ghardaqa. The intertidal zone at one of the impacted sites supported very poor algal vegetation, dominated by Phaeophyta in winter and spring and Rhodophyta in summer and autumn; at Quseir it was dominated by microfilamentous Rhodophya. At Ghardaqa, the intertidal macro-algal community was dominated by Phaeophyta. The results also showed that the abundance of marcroalgae reached its maximum in August at all the study sites, and that species diversity was significantly higher at Quseir than at the other two sites.